Skocz do pozycji: 1.

Tytuł:

Discrete Fourier transform and permutations

Autorzy:

Hui, S.
Żak, S. H.

Powiązania:

https://bibliotekanauki.pl/articles/202022.pdf

Data publikacji:

2019

Wydawca:

Polska Akademia Nauk. Czytelnia Czasopism PAN

Tematy:

discrete Fourier transform
DFT
DFT invariants
Fourier coefficients
permutations
DFT coefficient magnitudes
circulant matrix
pattern recognition

Opis:

It is well known that the magnitudes of the coefficients of the discrete Fourier transform (DFT) are invariant under certain operations on the input data. In this paper, the effects of rearranging the elements of an input data on its DFT are studied. In the one-dimensional case, the effects of permuting the elements of a finite sequence of length N on its Discrete Fourier transform (DFT) coefficients are investigated. The permutations that leave the unordered collection of Fourier coefficients and their magnitudes invariant are completely characterized. Conditions under which two different permutations give the same DFT coefficient magnitudes are given. The characterizations are based on the automorphism group of the additive group ZN of integers modulo N and the group of translations of ZN. As an application of the results presented, a generalization of the theorem characterizing all permutations that commute with the discrete Fourier transform is given. Numerical examples illustrate the obtained results. Possible generalizations and open problems are discussed. In higher dimensions, results on the effects of certain geometric transformations of an input data array on its DFT are given and illustrated with an example.

Źródło:

Bulletin of the Polish Academy of Sciences. Technical Sciences; 2019, 67, 6; 995-1005
0239-7528

Pojawia się w:

Bulletin of the Polish Academy of Sciences. Technical Sciences

Dostawca treści:

Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:

The origin of the interaction responsible for the difference of hole mobility of two derivatives of anthracene
Źródło powstania oddziaływań odpowiedzialnych za różnice ruchliwości dwu pochodnych antracenu

Autorzy:

Kania, S.
Kuliński, J.
Sikorski, D.

Powiązania:

https://bibliotekanauki.pl/articles/296681.pdf

Data publikacji:

2018

Wydawca:

Politechnika Łódzka. Wydawnictwo Politechniki Łódzkiej

Tematy:

anthrone
anthraquinone
DFT calculations
mobility
antron
antrachinon
obliczenia DFT
ruchliwość

Opis:

Hole mobility of the layers built from two anthracene derivatives differing in the substitution of the central benzene ring, i.e. anthrone substituted with only one keto group and anthraquinone substituted with two keto groups differs by one order of magnitude despite the fact that both have almost identical crystal structure. We ascribe this difference to existence of an additional intermolecular interaction arising in the layer of anthrone.
Wykazano, w przypadku antronu i antrachinonu będących pochodnymi antracenu podstawionego w środkowym pierścieniu jedną lub dwiema grupami ketonowymi obserwuje się jedynie małe i prawie identyczne zmiany aromatycznej energii stabilizacji (w zakresie 1%). Oba rozpatrywane związki mają prawie identyczną strukturę krystaliczną. Jednakże ruchliwość dziur w antronie jest o jeden rząd wyższa niż w antrachinonie, niezależnie, czy jest badana w warstwach amorficznych, quasi-amorficznych czy też krystalicznych. Dlatego też jedynym źródłem obserwowanej doświadczalnie różnicy ruchliwości nośników ładunku może być obecność dużego momentu dipolowego cząsteczki antronu w porównaniu do małej wartości momentu dipolowego cząsteczki antrachinonu.

Źródło:

Scientific Bulletin. Physics / Technical University of Łódź; 2018, 39; 27-35
1505-1013
2449-982X

Pojawia się w:

Scientific Bulletin. Physics / Technical University of Łódź

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 3.

Tytuł:

Cepstrum application in diagnostics of mechanical devices
O możliwości zastosowania cepstrum w diagnostyce urządzeń mechanicznych

Autorzy:

Kurowski, W.
Miranowski, K.

Powiązania:

https://bibliotekanauki.pl/articles/327908.pdf

Data publikacji:

2014

Wydawca:

Polska Akademia Nauk. Polskie Towarzystwo Diagnostyki Technicznej PAN

Tematy:

DFT
spectrum
cepstrum
widmo

Opis:

The paper presents one of the methods of digital processing of diagnostic signals such as cepstral analysis and the possibility of its application in the investigations of sources of wave disturbances. In order to solve the problem, simulation and diagnostic research was performed. The simulation experiment consisted in generating different sample signals (by special software) containing known frequency-related information, which aimed at exploring the information generated and presented in the cepstrum characteristics and its reliability. The diagnostic experiment was carried out on an mechanical device – a Ford Transit minivan. The object was a basis for the determination of the possibilities of practical application of the cepstrum characteristics.
W artykule przedstawiono jedną z metod cyfrowego przetwarzania sygnałów diagnostycznych jaką jest analiza cepstralna i możliwość jej zastosowania w diagnostyce urządzeń mechanicznych do badania źródeł zaburzeń. Dla rozwiązania zadania przeprowadzono badania symulacyjne i diagnostyczne. Eksperyment symulacyjny polegał na generowaniu w specjalnym programie różnych sygnałów próbnych, zawierających znane informacje częstotliwościowe, w celu zbadania informacji wytwarzanych i prezentowanych w charakterystyce cepstrum oraz ich wiarygodności. Natomiast eksperyment diagnostyczny, przeprowadzony na rzeczywistym urządzeniu mechanicznym, jakim był mikrobus Ford Transit, stanowił podstawę do określenia możliwości praktycznego zastosowania charakterystyki cepstrum.

Źródło:

Diagnostyka; 2014, 15, 4; 21-27
1641-6414
2449-5220

Pojawia się w:

Diagnostyka

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 4.

Tytuł:

Investigation of continuous change of α parameter in the interpolated DFT algorithm for cosα(X) windows

Autorzy:

Barczentewicz, S.

Powiązania:

https://bibliotekanauki.pl/articles/114624.pdf

Data publikacji:

2015

Wydawca:

Stowarzyszenie Inżynierów i Techników Mechaników Polskich

Tematy:

DFT analysis
interpolated DFT
estimation of frequency channel number
cosα(X) windows

Opis:

Currently known IpDFT algorithms use the cosα(X) windows with the step change of the window’s order. This work presents IpDFT method designed for the signal analyzed with cosα(X) window, which allows continuous change of the window’s parameter α, so that a full regulation of the sidelobes position becomes possible. Proposed algorithm is a generalization of known IpDFT solutions for cosα(X) windows.

Źródło:

Measurement Automation Monitoring; 2015, 61, 4; 90-91
2450-2855

Pojawia się w:

Measurement Automation Monitoring

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 5.

Tytuł:

An approach for electrical harmonic analysis based on interpolation DFT

Autorzy:

Jiao, Lina
Du, Yang

Powiązania:

https://bibliotekanauki.pl/articles/2086690.pdf

Data publikacji:

2022

Wydawca:

Polska Akademia Nauk. Czytelnia Czasopism PAN

Tematy:

electrical harmonic analysis
DFT
interpolation

Opis:

The discrete Fourier transform (DFT) is the main method of electrical harmonic analysis since it’s easily realized in an embedded system. But there were some difficulties in performing synchronized sampling. The spectral leakage caused by asynchronous sampling affects the accuracy of harmonics analysis. Using window functions and interpolation algorithms can improve the accuracy of harmonics analysis. An approach for electrical harmonic analysis based on the interpolation DFT was proposed. A window function reduces DFT leakage and the interpolation algorithm modifies the calculation results of frequency, amplitude and the initial phase angle. The simulation results indicate that, by using the interpolation DFT electrical harmonic analysis method based on the Hanning window or the Blackman window, the error of calculating amplitudes and frequencies is not greater than 0.5%.

Źródło:

Archives of Electrical Engineering; 2022, 71, 2; 445--454
1427-4221
2300-2506

Pojawia się w:

Archives of Electrical Engineering

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 6.

Tytuł:

Study on a novel hydroxamic acid as the collector of rhodochrosite

Autorzy:

Zhao, G.
Dai, T.
Wang, S.
Zhong, H.

Powiązania:

https://bibliotekanauki.pl/articles/110816.pdf

Data publikacji:

2018

Wydawca:

Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej

Tematy:

flotation
rhodochrosite
hydroxamic acid
DFT

Opis:

A novel collector, tert-butyl benzohydroxamic acid (TBHA), was first introduced in rhodochrosite flotation. The performance of TBHA was investigated by the density functional theory (DFT) calculation along with the micro flotation test, zeta potential determination and XPS analysis, compared with benzohydroxamic acid (BHA). TBHA has stronger affinity to the mineral than BHA in terms of frontier molecular orbital, atomic net charge and bond population. The substitution of tert-butyl group on the benzene ring improves the affinity of the hydroxamic acid to the mineral. TBHA exhibits excellent collecting ability to rhodochrosite with a recovery of about 99% at a concentration of 3.89×10-4 mol/dm3 and pH 6.5. The hydroxamic acid molecules are adhered on mineral surfaces by chemical adsorption, resulting in negative shifts for the zeta potential of rhodochrosite with the presence of the collector. Chemical adsorption can be also confirmed from XPS analyses that the atomic concentration ratios of C and O to Mn on the treated mineral surfaces were increased and the binding energy of Mn3s was decreased. The experimental data achieve excellent agreement with the computational analyses.

Źródło:

Physicochemical Problems of Mineral Processing; 2018, 54, 2; 428-439
1643-1049
2084-4735

Pojawia się w:

Physicochemical Problems of Mineral Processing

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 7.

Tytuł:

Nitrogen-doped pyrene as a catalyst for fuel cells

Autorzy:

Chudoba, Anna

Powiązania:

https://bibliotekanauki.pl/articles/1179638.pdf

Data publikacji:

2017

Wydawca:

Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN

Tematy:

DFT
fuel cells
oxygen reduction reaction

Opis:

Density functional theory (DFT) was applied to study nitrogen-doped pyrene as an oxygen reduction reaction (ORR) cathode catalyst for fuel cells. Transition states and energy barriers were calculated to predict the catalytic properties of this substance.

Źródło:

World Scientific News; 2017, 72; 61-68
2392-2192

Pojawia się w:

World Scientific News

Dostawca treści:

Biblioteka Nauki

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Skocz do pozycji: 8.

Tytuł:

Interaction between sphalerite and pyrite and its effect on surface oxidation of sphalerite

Autorzy:

Yang, B.
Xie, X.
Tong, X.
Lan, Z.
Cui, Y.

Powiązania:

https://bibliotekanauki.pl/articles/109553.pdf

Data publikacji:

2018

Wydawca:

Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej

Tematy:

sphalerite
surface oxidation
minerals interaction
DFT

Opis:

The interaction between sphalerite and pyrite was investigated by dissolution test, X-ray photoelectron spectroscopy (XPS), zeta potential measurement and density functional theory (DFT) calculation. Dissolution tests indicated that sphalerite dissolution was promoted due to the galvanic interaction between sphalerite and pyrite. The Zn2+ ion concentration increased with increasing pyrite content and dissolved time. XPS analysis results demonstrated that a new oxidation product was formed on the sphalerite surface in the presence of pyrite in a pulp. Zeta potential measurements showed that the isoelectric point of sphalerite increased from 3.3 to 5.4 due to galvanic interaction. DFT calculation results suggested that electron transfer from sphalerite to pyrite occurred when they contacted. The Zn 4s and S 3p states of sphalerite lost electrons. The Fe 4p and 4s of pyrite states obtained electrons, and Fe 3d and S 3s states lost a small number of electrons. The surface oxidation of sphalerite was promoted due to the interaction with pyrite, and the collectorless floatability of sphalerite decreased.

Źródło:

Physicochemical Problems of Mineral Processing; 2018, 54, 2; 311-320
1643-1049
2084-4735

Pojawia się w:

Physicochemical Problems of Mineral Processing

Dostawca treści:

Biblioteka Nauki

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Skocz do pozycji: 9.

Tytuł:

Ab Initio Study of Structure, Electronic and Magnetic Properties of YFe5 Phase Compound in the DFT Formalism

Autorzy:

Gruszka, K.
Nabiałek, M.
Noga, T

Powiązania:

https://bibliotekanauki.pl/articles/352079.pdf

Data publikacji:

2016

Wydawca:

Polska Akademia Nauk. Czytelnia Czasopism PAN

Tematy:

DFT
magnetism
electronic structure
structural parameters

Opis:

Paper presents results of studies on structural, electronic and magnetic properties of YFe₅ compound using density functional theory (DFT) approach. The GGA functional with ultrasoft pseudopotentials were used as implemented in Quantum Espresso software. The structure of YFe₅ compound was examined in three different states namely nonmagnetic, antiferromagnetic and ferromagnetic. Also two antiferromagnetic configurations were considered. From the total energy viewpoint the most likely ferromagnetic configuration is favorable. In order to achieve mentioned aims we present projected density of states, electronic band structure and Löwdin population analysis studies results.

Źródło:

Archives of Metallurgy and Materials; 2016, 61, 1; 369-374
1733-3490

Pojawia się w:

Archives of Metallurgy and Materials

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 10.

Tytuł:

Electrical and thermal properties of anthrone
Elektryczne i termiczne własności antronu

Autorzy:

Kania, Sylwester
Kuliński, Janusz
Sikorski, Dominik

Powiązania:

https://bibliotekanauki.pl/articles/2022177.pdf

Data publikacji:

2020

Wydawca:

Politechnika Łódzka. Wydawnictwo Politechniki Łódzkiej

Tematy:

anthrone
differential scanning calorimetry
DSC
reorganization energy
DFT calculations
antron
różnicowa kalorymetria skaningowa
energia reorganizacji
obliczenia DFT

Opis:

Electrical and thermal properties of anthrone Quantum-chemical density functional theorem (DFT) calculations indicate that the value of the reorganization energy indicates the possibility of efficient hole capture by the anthrone molecule during transport process of charge carriers. Differential scanning calorimetry (DSC) studies indicate the temperature stability of anthrone molecules above the melting point up to 164°C. The glass transition is determined at 153.7°C and melting point at 157.05°C.
Obliczenia funkcjonału kwantowo-chemicznego (DFT) wskazują, że wartość energii reorganizacji wskazuje na możliwość efektywnego wychwytywania dziur przez cząsteczkę antronu podczas transportu nośników ładunku. Badania metodą różnicowej kalorymetrii skaningowej (DSC) wskazują na stabilność temperaturową cząsteczek antronu powyżej temperatury topnienia do 164°C. Temperaturę zeszklenia określono jako Tg = 153,7°C, a temperaturę topnienia jako Tc = 157,05°C.

Źródło:

Scientific Bulletin. Physics / Technical University of Łódź; 2020, 41; 43-51
1505-1013
2449-982X

Pojawia się w:

Scientific Bulletin. Physics / Technical University of Łódź

Dostawca treści:

Biblioteka Nauki

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Skocz do pozycji: 11.

Tytuł:

Selective arylation of phenol proteted propygyl bromide via pd-catalysed Suzuki coupling reaction: synthesis, mechanistic studies by DFT calculations and Their Pharmacological Aspects

Autorzy:

farooq, hira
rasool, nasir
Ansari, Muhammad T.
rizwan, komal
mahmood, tariq
israr, hira
Ayub, Khurshid
rasheed, tahir
Zareen, Seema
Akhtar, muhammad N.
iqbal, sarosh

Powiązania:

https://bibliotekanauki.pl/articles/895304.pdf

Data publikacji:

2018-08-31

Wydawca:

Polskie Towarzystwo Farmaceutyczne

Tematy:

biofilm
phenol
DFT
Suzuki coupling
organoboron
Biaryl

Opis:

Biaryls are the potential source of synthetic drugs. The present study describes the synthesis of a series of functionalized biphenyl derivatives (3a-3g) using Pd-catalyzed Suzuki coupling reaction. The experimental results revealed the facile synthesis of biphenyl derivatives (3a-3g) with notably high yield (80-88 %). Density functional theory (DFT) studies were performed by Gaussian 09 software in order to rationalize the selectivity of coupling at C-Br bond instead of C-Cl bond. In addition of synthesis, the biological activities (biofilm inhibition, hemolytic and anti-thrombolytic) of these novel compounds were investigated. These results exhibited good biofilm inhibition (5.86-65.8 %), hemolytic (1.32-30.1 %) and anti-thrombolytic activities (9.64-42.5 %), indicating the potential use of these compounds for pharmaceutical applications.

Źródło:

Acta Poloniae Pharmaceutica - Drug Research; 2018, 75, 4; 911-919
0001-6837
2353-5288

Pojawia się w:

Acta Poloniae Pharmaceutica - Drug Research

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 12.

Tytuł:

Mechanic, Half-Metallic and Thermoelectric Properties of the PdZrTiAl under pressure: A DFT study

Autorzy:

Parsamehr, S.
Boochani, A.
Sartipi, E.
Amiri, M.
Solaymani, S.
Naderi, S.
Aminian, A.

Powiązania:

https://bibliotekanauki.pl/articles/354036.pdf

Data publikacji:

2020

Wydawca:

Polska Akademia Nauk. Czytelnia Czasopism PAN

Tematy:

PdZrTiAl
half-metal
thermoelectric
elastic constants
DFT

Opis:

The half-metallic, mechanical, and transport properties of the quaternary Heusler compound of PdZrTiAl is discussed under hydrostatic pressures in the range of –11.4 GPa to 18.4 GPa in the framework of the density functional theory (DFT) and Boltzmann quasi-classical theory using the generalization gradient approximation (GGA). By applying the stress, the band gap in the minor spin increases so that the lowest band is obtained 0.25 eV at the pressure of –11.4 GPa while the maximum gap is calculated 0.9 eV at the pressure of 18.4 GPa. In all positive and negative pressures, the PdZrTiAl composition exhibits a half-metallic behavior 100% spin polarization at the Fermi level. It is also found that applying stress increases the Seebeck coefficient in both spin directions. In the minority spin, the n-type PdZrTiAl, the power factor (PF) for all the cases is greater in the equilibrium state than the strain and stress conditions whereas in the majority spin, the PF value of the stress state is greater than the other two. The non-dimensional figure of merit (ZT) is significant and is about one in spin down in the room temperature for the all pressure states that it remains on this value by applying pressure. The obtained elastic constants indicate that the PdZrTiAl crystalline structure has a mechanical stability. Based on the Yong (E), Bulk (B) and shear (G) modulus and Poisson (n) ratio, the brittle-ductile behavior of this compound has been investigated under pressure. The results indicate that PdZrTiAl has a ductile nature and it is a stiffness compound in which elastic and mechanical instability increases by applying strain.

Źródło:

Archives of Metallurgy and Materials; 2020, 65, 1; 459-470
1733-3490

Pojawia się w:

Archives of Metallurgy and Materials

Dostawca treści:

Biblioteka Nauki

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Skocz do pozycji: 13.

Tytuł:

Improving the carbon dioxide uptake efficiency of activated carbons using a secondary activation with potassium hydroxide

Autorzy:

Zgrzebnicki, M.
Michalczyszyn, E.
Wrobel, R. J.

Powiązania:

https://bibliotekanauki.pl/articles/778515.pdf

Data publikacji:

2018

Wydawca:

Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie

Tematy:

activated carbon
activation
pore size distribution
DFT

Opis:

Secondary activation of commercial activated carbon (AC) ORGANOSORB 10-CO was carried out at 600, 700 and 800°C with mass ratios of potassium to AC (K/AC) in range 1–3. Crucial samples have shown following CO₂  uptakes and SSA – 3.90 mmol/g and 1225 m²/g, 4.54 mmol/g and 1546 m²/g, 4.28 and 1717 m²/g for pristine material and samples obtained at 700°C with K/AC = 2 and at 800°C with K/AC = 3 respectively. Last sample also indicated significant mesopore volume increase in diameter range 2–5 nm, from 0.11 to 0.24 cm3/g. CO₂ uptake increase was explained by formation of micropores up to diameter of 0.8 nm, which distribution was established from CO₂  sorption using DFT. Surface chemistry of all samples has not changed during modification, what was proven by XPS. Moreover, deeper incorporation of potassium ions into graphite at higher temperatures was observed as confirmed with EDS, XPS and XRD.

Źródło:

Polish Journal of Chemical Technology; 2018, 20, 3; 87-94
1509-8117
1899-4741

Pojawia się w:

Polish Journal of Chemical Technology

Dostawca treści:

Biblioteka Nauki

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Skocz do pozycji: 14.

Tytuł:

Nano-design of Zeolites Biomass Wastes Valorization: Dehydration of Lactic Acid into Acrylic Acid

Autorzy:

Kurzydym, Izabela
Czekaj, Izabela

Powiązania:

https://bibliotekanauki.pl/articles/319290.pdf

Data publikacji:

2019

Wydawca:

Polskie Towarzystwo Przeróbki Kopalin

Tematy:

metoda DFT
nanocząstki metaliczne
odwodnienie kwasu mlekowego
kwas akrylowy
DFT methods
metalic nanoparticles
lactic acid dehydration
acrylic acid

Opis:

The valorization of waste from biomass currently arouses great interest. In the present study we concentrate on the design of innovative BEA zeolite catalysts with applied metal nanoparticles - copper, vanadium and manganese for the dehydration of lactic acid to acrylic acid. The ab initio method based on density functional theory (DFT) was used to calculate the electron structure of the analyzed molecules. The non-local generalized gradient corrected functionals GGA-RPBE was used to in order to account for electron exchange and correlation. The cluster model was represented by a hierarchical zeolite M2Al2Si12O40H22 (M = Cu, V, Mn). The stabilization of the M-Ob-M dimer complex in the hierarchical structure of BEA, mechanism of adsorption of lactic acid on BEA zeolite with applied metal dimers and formation of acrylic acid on these zeolites were investigated. The examined metals form stable dimers interconnected by a bridge oxygen (Ob). Adsorption of lactic acid takes place in the vicinity of a dimer of M-Ob-M. The dehydration of lactic acid to acrylic acid in all cases consists in the separation of the hydroxyl group and creating a connection with a metal center of dimer and disconnection of a single hydrogen atom from the methyl group and its interaction with bridge oxygen of dimer.
Waloryzacja odpadów z biomasy cieszy się obecnie dużym zainteresowaniem. W niniejszych badaniach koncentrujemy się na projektowaniu innowacyjnych katalizatorów zeolitowych BEA z nanocząstkami metali - miedzi, wanadu i manganu w celu odwodnienia kwasu mlekowego do kwasu akrylowego. Metoda ab initio oparta na teorii funkcjonalności gęstości (DFT) została wykorzystana, przy użyciu nielokalnego funkcjonału korelacyjno-wymiennego GGA-RPBE, do obliczenia struktury elektronowej analizowanych cząsteczek. Hierarchiczny zeolite BEA był reprezentowany przez model klasterowy M2Al2Si12O40H22 (M = Cu, V, Mn). Badano stabilizację dimeru M-Ob-M w hierarchicznej strukturze BEA, mechanizm adsorpcji kwasu mlekowego na zeolicie BEA z zastosowanymi dimerami metali i tworzenie kwasu akrylowego na tych zeolitach. Badane metale tworzą stabilne dimery połączone wzajemnie tlenem mostkowym (Ob). Adsorpcja kwasu mlekowego odbywa się w pobliżu dimeru M-Ob-M. Odwodnienie kwasu mlekowego do kwasu akrylowego we wszystkich przypadkach polega na oddzieleniu grupy hydroksylowej i utworzeniu połączenia z jednym z metali dimeru i odłączeniem pojedynczego atomu wodoru od grupy metylowej kwasu mlekowego i jego oddziaływaniem z tlenem mostkowym dimeru.

Źródło:

Inżynieria Mineralna; 2019, 21, 1; 169-172
1640-4920

Pojawia się w:

Inżynieria Mineralna

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 15.

Tytuł:

Zastosowanie MDFT do analizy widmowej sygnałów okresowych próbkowanych niesynchronicznie
Application of the MDFT in spectral analysis of non-coherently sampled periodic signals

Autorzy:

Kłosiński, R.

Powiązania:

https://bibliotekanauki.pl/articles/152000.pdf

Data publikacji:

2008

Wydawca:

Stowarzyszenie Inżynierów i Techników Mechaników Polskich

Tematy:

modyfikowane DFT
analiza widmowa
niesynchroniczne próbkowanie
przeciek widma
modified DFT
spectrum estimation
non-coherent sampling
spectrum leakage effect

Opis:

MDFT to modyfikowane DFT dające zdecydowaną redukcję przecieku widma i poprawę dokładności estymacji harmonicznych sygnałów okresowych próbkowanych niesynchronicznie. Przedstawione zostały idea, wyprowadzenie, źródła błędów oraz sposób i skutki stosowania okien sygnałowych. Zaprezentowano wyniki analizy widmowej wygenerowane-go oraz rzeczywistego sygnału pokazujące możliwość wyznaczania widma amplitudowego i fazowego za pomocą MDFT z dokładnością znacznie większą w porównaniu z m algorytmem DFT. MDFT może znaleźć zastosowanie do analizy sygnałów występujących w systemie elektroenergetycznym, gdzie naturalna zmienność częstotliwości utrudnia analizę.
The paper subject is the identification of periodic signal harmonics on the basis of samples in case of a non-coherent sampling. The modification of DFT is presented which leads to a distinct minimization of spectrum leakage effect and improvement in signal harmonics estimation accuracy. The modification consists in adjusting base functions frequencies of the Fourier series to frequencies of analyzed signal harmonics. The paper presents ideas, introduction, error analysis of the method and signal windowing effects for the modified discrete Fourier transform (MDFT). The presented examples indicate the possibility to determine amplitude and phase spectrums with higher accuracy in comparison to the classical DFT. Signal spectrum estimation by means of MDFT can be used for signal analysis in an electro-energetic system, where natural frequency variability hinders the analysis.

Źródło:

Pomiary Automatyka Kontrola; 2008, R. 54, nr 6, 6; 337-339
0032-4140

Pojawia się w:

Pomiary Automatyka Kontrola

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 16.

Tytuł:

The DFT study on the electronic structure of boronic acid derivatives and its esters with fructose

Autorzy:

Kur, K.
Kowalska-Baron, A.
Miller, E.

Powiązania:

https://bibliotekanauki.pl/articles/410471.pdf

Data publikacji:

2018

Wydawca:

Politechnika Łódzka. Wydawnictwo Politechniki Łódzkiej

Tematy:

boronic acid derivatives
TD-DFT method
boronic esters with fructose
pochodne kwasu boronowego
metoda TD-DFT
estry boronowe

Opis:

Theoretical investigations are carried out to examine the geometrical structure and parameters of electron transitions to the lowest excited states of two boronic acid derivatives: 3-aminophenylboronic acid and 3-(acetamidomethyl)phenyl boronic acid and its cycling esters with fructose, using the DFT based 6-31 G(d,p) method. The most stable ester isomer of each acid has been selected. Predicted excitation wavelength are shorter (less than 0.5 eV) than experimental ones, what is in a good agreement considering limitations of the DFT method. In case of almost every calculated molecule the analysis of electronic transitions shows that transition S0→S1 involves electron transfer mainly from the HOMO to LUMO orbital.

Źródło:

Biotechnology and Food Science; 2018, 82, 1; 29-39
2084-0136
2299-6818

Pojawia się w:

Biotechnology and Food Science

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 17.

Tytuł:

Efektywność estymacji parametrów sygnału harmonicznego metodą wielopunktowej interpolowanej DFT
Efficiency of the Multipoint Interpolated DFT method in harmonic signal parameter estimation

Autorzy:

Domańska, A.
Grząślewicz, P.

Powiązania:

https://bibliotekanauki.pl/articles/153890.pdf

Data publikacji:

2013

Wydawca:

Stowarzyszenie Inżynierów i Techników Mechaników Polskich

Tematy:

okno Hanninga
DFT
interpolacja
Hanning window
interpolation

Opis:

Artykuł dotyczy zagadnienia estymacji widma sygnałów periodycznych metodą DFT z dodatkowym przetwarzaniem – zastosowaniem okna oraz interpolacją dwu i trzy punktową. Przedstawiono zasadę takiej estymacji w przypadku okna prostokątnego i Hanninga oraz zanalizowano efektywność każdego z wariantów. Przedstawiono interfejs programu, wykonany w celu zobrazowania i śledzenia graficznych i liczbowych wyników estymacji. Program i graficzny interfejs użytkownika mogą mieć zastosowanie w wirtualnym analizatorze widma o podwyższonej dokładności. W artykule tym przedstawiono dwie metody estymacji częstotliwości i amplitudy. Obie metody używały okien Hanninga i prostokątnego. Okazało się metoda trzy punkowej estymacji WMIpDFt osiąga lepsze rezultaty, posługując się kryterium wartości błędu bezwzględnego. Wartości te są mniejsze niż w przypadku stosowania metody estymacji dwu punktowej IpDFT. Jednak użycie prostokątnego okna w trzy punktowej estymacji generuje mniejszy błąd. Dla efektywnej estymacji amplitudy lepszym okazuje się zastosowanie okna Hanninga dla obu metod estymacji. Najmniejszy bezwzględny błąd jest otrzymywany dla estymacji amplitudy z wykorzystaniem dwupunktowej estymacji IpDFT oraz okna Hanninga.
The paper deals with estimation of periodic signal spectra using the DFT method with additional processing (application of time window and two-point and three-point interpolation). The efficiency of esti-mation with the rectangular and Hanning window is analyzed. There is presented a program interface created for tracking graphical and numerical results of estimation. The graphical interface and the simulation program can be used in a high precision spectrum analyzer. In this paper two methods of frequency and amplitude estimation are discussed. Both methods use the Hanning and rectangular window. It turns out that the three-point WMIpDFT method gives better results, using the absolute error value criterion. The values of the absolute error are smaller than those in case of using the two-point IpDFT. However, use of rectangular window in the three-point estimation creates a lower error value. For the effective amplitude estimation it is better to use the Hanning window for both methods. The lowest absolute error value is obtained for the amplitude estimation with use of the two-point IpDFT method with the Hanning window.

Źródło:

Pomiary Automatyka Kontrola; 2013, R. 59, nr 5, 5; 422-424
0032-4140

Pojawia się w:

Pomiary Automatyka Kontrola

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 18.

Tytuł:

Contemplation on the protonation of TEX

Autorzy:

Türker, L.

Powiązania:

https://bibliotekanauki.pl/articles/358113.pdf

Data publikacji:

2014

Wydawca:

Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego

Tematy:

TEX
explosives
ethers
acetals
decomposition
DFT calculations

Opis:

The possibility of acid catalyzed decomposition of TEX, a well known explosive, is considered by investigating the stability of cations formed by protonation at different sites in the molecule. For this purpose, density functional theory has been employed at the B3LYP/6-31++G(d,p) and B3LYP/6-31G(d,p) levels. Various simple cations, as well as hydrogen-bridged cations of TEX and carbocations formed from protonated TEX, are considered which may undergo further acid catalyzed cleavage routes of the molecule.

Źródło:

Central European Journal of Energetic Materials; 2014, 11, 2; 307-319
1733-7178

Pojawia się w:

Central European Journal of Energetic Materials

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 19.

Tytuł:

A Study of the Detonation Properties, Propellant Impulses, Impact Sensitivities and Synthesis of Nitrated ANTA and NTO Derivatives

Autorzy:

Jensen, T. L.
Moxnes, J. F.
Kjønstad, E. F.
Unneberg, E.

Powiązania:

https://bibliotekanauki.pl/articles/358234.pdf

Data publikacji:

2016

Wydawca:

Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego

Tematy:

detonation properties
propellant impulses
DFT
NTO
ANT

Opis:

Nitrated derivatives of 5-amino-3-nitro-1,2,4-triazole (ANTA) and 3-nitro-1,2,4-triazol-5-one (NTO) were theoretically characterized with respect to their performance as high explosives and rocket propellants. The detonation velocity and the detonation pressure of the derivatives, calculated with EXPLO5 software, were at the same level or slightly above the performance of 1,3,5-trinitroperhydro-1,3,5-triazine (RDX). The results showed that compositions of 1,3,4-trinitro-1,2,4-triazol-5-one and glycidyl azide polymer (GAP) could give specific impulses just above 2600 m/s in rocket propellants. The sensitivities of the derivatives were evaluated using their heats of detonation, CHNO-ratios, free space in the crystal lattice and N−NO2 bond dissociation energy. The stability and sensitivity of several of the derivatives could be poor due to the low N−NO2 bond dissociation energies. The N−NO2 bond dissociation energies in the derivatives were calculated to be between 41 and 296 kJ/mol when the M06-2X/6-311+G(2d,p) functional was used. Synthetic routes for the most stable derivatives were proposed. In addition, preliminary studies of the chloride-assisted nitrolysis of NTO were performed. The infrared spectrum of the NTO derivative indicated that N−NO2 bonds were formed.

Źródło:

Central European Journal of Energetic Materials; 2016, 13, 2; 445-467
1733-7178

Pojawia się w:

Central European Journal of Energetic Materials

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 20.

Tytuł:

Design and Evaluation of the Thermal Properties of Di-, Tri- and Tetra-Azido-Esters

Autorzy:

Kumar, S.
Kumar, A.
Yamajala, K. D. B.
Gaur, P.
Kumar, D.
Banerjee, S.

Powiązania:

https://bibliotekanauki.pl/articles/358266.pdf

Data publikacji:

2017

Wydawca:

Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego

Tematy:

azido-esters
energetic plasticizers
DFT
contact angle

Opis:

A group of polycyclic and aliphatic azido-esters (as energetic plasticizers) have been synthesized by simple synthetic routes and their molecular structures were confirmed by spectroscopic techniques. In addition, their thermal and rheological properties have been determined utilizing DSC, TGA, viscosity, and contact angle. Computational studies of these plasticizers have been performed by means of DFT (B3LYP/6-31G*) to estimate possible stable structures, energies, heat of formation, bond dissociation energies, IR and NMR spectra etc. Their compatibility with glycidyl azide polymer (GAP) binder was studied to explore their applicability in propellants. All of these molecules are novel and have been synthesized with the possibility of scale up.

Źródło:

Central European Journal of Energetic Materials; 2017, 14, 4; 844-860
1733-7178

Pojawia się w:

Central European Journal of Energetic Materials

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 21.

Tytuł:

Amplitude value error of periodic signal as a two-dimensional random variable

Autorzy:

Purczyński, J.

Powiązania:

https://bibliotekanauki.pl/articles/97716.pdf

Data publikacji:

2012

Wydawca:

Politechnika Poznańska. Wydawnictwo Politechniki Poznańskiej

Tematy:

random variable
Dirichlet window
DFT
signal amplitude

Źródło:

Computer Applications in Electrical Engineering; 2012, 10; 29-40
1508-4248

Pojawia się w:

Computer Applications in Electrical Engineering

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 22.

Tytuł:

DFT study of coadsorption of fatty acid and kerosene on fluorapatite (001) surface

Autorzy:

Du, Weifan
Li, Xianbo
Zhang, Qin

Powiązania:

https://bibliotekanauki.pl/articles/2200343.pdf

Data publikacji:

2023

Wydawca:

Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej

Tematy:

fluorapatite surface
fatty acid
kerosene
coadsorption
DFT

Opis:

The adsorption of fatty acid, kerosene and fatty acid-kerosene on fluorapatite (001) surface were investigated by density functional theory (DFT) calculations. The results showed that the single fatty acid could form stable chemisorption on fluorapatite (001) surface by the O of fatty acids bonding with Ca1 site. The single kerosene could not be stably adsorbed on fluorapatite (001) surface because the H of kerosene did not form hydrogen bond with the O of PO43- on (001) surface (Osurf). For the coadsorption conformation, the chemisorption of fatty acid-kerosene on fluorapatite (001) surface was contributed by the interaction between O of fatty acids and Ca1, the H of kerosene did not bond with the Osurf, but the carbon chain length of kerosene has a large influence on the coadsorption. Compared with the coadsorption of fatty acid-decane, the adsorption of butyric acid-tetradecane and octanoic acid-tetradecane on fluorapatite (001) surface have greater adsorption energies and overlapping region of DOS between O 2p and Ca 4d, indicating that there is a synergistic effect between fatty acid and tetradecane. Meanwhile, the collaborative effects exist between the molecules of fatty acids. The interpenetrating adsorption of fatty acid and kerosene on the fluorapatite surface could improve the adsorption strength and density. The flotation test further confirmed that the single kerosene could not collect fluorapatite, but it could be collected by the single fatty acid. Besides, the synergistic effect between fatty acid and kerosene could increase the flotation recovery of fluorapatite.

Źródło:

Physicochemical Problems of Mineral Processing; 2023, 59, 1; art. no. 161890
1643-1049
2084-4735

Pojawia się w:

Physicochemical Problems of Mineral Processing

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 23.

Tytuł:

Konformacyjne właściwości modyfikowanych reszt aminokwasowych
Conformational properties of modified amino acid residues

Autorzy:

Wałęsa, R.
Buczek, A.
Broda, A.

Powiązania:

https://bibliotekanauki.pl/articles/143003.pdf

Data publikacji:

2014

Wydawca:

Stowarzyszenie Inżynierów i Techników Przemysłu Chemicznego. Zakład Wydawniczy CHEMPRESS-SITPChem

Tematy:

dehydrofenyloalanina
N-metylowanie
analiza konformacyjna
obliczenia DFT
wpływ rozpuszczalnika
dehydrophenylalanine
N-methylation
conformational analysis
DFT calculations
solvent impact

Opis:

Konformacyjnie usztywnione aminokwasy są szeroko stosowane przy konstruowaniu peptydowych analogów o lepszych właściwościach farmako-kinetycznych. Jednym z sposobów modyfikacji peptydów jest wprowadzenie reszt a,b-dehydroaminokwasowych w łańcuch peptydowy. Podwójne wiązanie Ca=Cb usztywnia łańcuch boczny i umożliwia występowanie izomerii geometrycznej Z/E. Innym rodzajem modyfikacji jest zastąpienie amidowej grupy –NH grupą –NCH3, czyli tzw. N-metylowanie. Autorzy określili wpływ tych dwóch modyfikacji strukturalnych na konformację łańcucha peptydowego. Przeprowadzone badania pozwoliły ustalić, że reszta a,b-dehydrofenyloalaniny aminokwasów konformacji H. Wykazano również, że polarny rozpuszczalnik zwiększa wyraźnie udział konfiguracji cis wiązania amidowego w N-metylowanych peptydach.
Conformationally constrained amino acids are widely used in the design of peptide analogues with better pharmacokinetic properties. One of the methods of peptide modification is the introduction of a, b -dehydroamino acid residues into peptide chain. The double bond Ca=Cb constrains side chain and enables occurrence of geometrical isomerism Z/E. The other type of modification is the replacement of amide group –NH with group –NCH3, i.e. so called N-methylation. The Authors have determined the impact of these two structural modifications on peptide chain conformation. Conducted research has lead to the conclusion that -dehydrophenylalanine residue has the ability to exhibit atypical for standard amino acids H conformation. It has also been shown that polar solvent clearly increase percentage of cis configuration of amide bond in N-methylated peptides.

Źródło:

Chemik; 2014, 68, 4; 329-334
0009-2886

Pojawia się w:

Chemik

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 24.

Tytuł:

Analiza metrologiczna interpolacji DFT metodą uzupełniania zerami
Metrological analysis of the DFT padding zeros interpolation method

Autorzy:

Borkowski, J.
Mroczka, J.

Powiązania:

https://bibliotekanauki.pl/articles/155961.pdf

Data publikacji:

2007

Wydawca:

Stowarzyszenie Inżynierów i Techników Mechaników Polskich

Tematy:

uzupełnianie zerami
interpolacja DFT
analiza sygnału wieloczęstotliwościowego
estymacja widma
padding zeros
DFT interpolation
multi-frequncy signal analysis
spectrum estimation

Opis:

Praca przedstawia analizę metrologiczną metody estymacji parametrów sygnału będącego sumą składowych sinusoidalnych wykorzystującej technikę okien danych i dyskretnego przekształcenia Fouriera (DFT) przy uzupełnianiu próbek sygnału próbkami zerowymi - tzw. metody uzupełniania zerami (ang. padding zeros). Przeprowadzona analiza metrologiczna prezentuje zależności na maksymalne błędy estymacji amplitud i częstotliwości składowych oscylacji sinusoidalnych w zależności od liczby dodawanych próbek zerowych i charakterystyki częstotliwościowej na przykładzie okna trójkątnego.
The paper presents the metrological analysis the parameters estimation method of signal being the sum of sinusoid components, used data windows technique and discrete Fourier transform (DFT) with padding signal proboes by zeros probes - so-called padding zeros method. Realized metrological analysis describes the dependences for maximum estimation errors of amplitudes and frequencies of component sinusoidal oscillaations as a function of the number of zero samples, frequency characteristic of data window on the triangle window example.

Źródło:

Pomiary Automatyka Kontrola; 2007, R. 53, nr 9 bis, 9 bis; 127-129
0032-4140

Pojawia się w:

Pomiary Automatyka Kontrola

Dostawca treści:

Biblioteka Nauki

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Skocz do pozycji: 25.

Tytuł:

Crystal structures and conformers of CyMe4-BTBP

Autorzy:

Lyczko, K.
Ostrowski, S.

Powiązania:

https://bibliotekanauki.pl/articles/147806.pdf

Data publikacji:

2015

Wydawca:

Instytut Chemii i Techniki Jądrowej

Tematy:

conformers
crystal structure
CyMe4-BTBP
DFT calculations

Opis:

The crystal structure of new conformation of the CyMe4-BTBP ligand (ttc) has been presented. The ttt conformer of this compound in a form of THF solvate has been also crystallized. The geometries of six possible conformations (ttt, ttc, tct, tcc, ctc and ccc) of the CyMe4-BTBP ligand have been modeled in the gas phase and in solutions (MeOH and H2O) by DFT calculations using B3LYP/6-31G(d,p) method. According to the calculations, in the three different media the conformers with trans orientation of the N atoms in the bipyridyl moiety are the most stable.

Źródło:

Nukleonika; 2015, 60, No. 4, part 2; 853-857
0029-5922
1508-5791

Pojawia się w:

Nukleonika

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 26.

Tytuł:

DFT and TOF-SIMS study of the interaction between hydrogen sulfide ion and malachite (–201) surface

Autorzy:

Mao, Yingbo
Wu, Dandan
Huang, Lingyun

Powiązania:

https://bibliotekanauki.pl/articles/1447053.pdf

Data publikacji:

2021

Wydawca:

Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej

Tematy:

malachite
hydrogen sulfide ions
sulfidation
DFT
TOF-SIMS

Opis:

In this paper, the mechanism of interaction between hydrogen sulfide ions and malachite was investigated using density functional theory (DFT) calculations and time of flight secondary ion mass spectrometry (TOF-SIMS). The DFT calculations showed that HS− adsorption on the malachite (−201) surface was stronger than that of S adsorption resulting from the higher number of electron transfers in the solution which accelerated the sulfidation reaction rate. Density of states (DOS) analysis showed that the near Fermi level was jointly contributed to by the Cu 3d, O 2p, O 2S, and S 3P orbits after adsorption of HS− on the malachite (–201)surface. It was found that the 2p orbital of O and the 3p orbital of S overlapped, indicating that S not only reacted with Cu, but also with O. The TOF-SIMS detected S− and CuS2− fragment ion peaks in the 0−150 m/z negative segment of mass spectra. TOF-SIMS also showed that copper sulfide films of certain thicknesses were formed, demonstrating the effectiveness of hydrogen sulfide sulfidation in flotation processes.

Źródło:

Physicochemical Problems of Mineral Processing; 2021, 57, 5; 71-79
1643-1049
2084-4735

Pojawia się w:

Physicochemical Problems of Mineral Processing

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 27.

Tytuł:

An approach to power system harmonic analysis based on triple-line interpolation discrete Fourier transform

Autorzy:

Liu, Ling
Zhang, Jinsong

Powiązania:

https://bibliotekanauki.pl/articles/2135741.pdf

Data publikacji:

2022

Wydawca:

Polska Akademia Nauk. Czytelnia Czasopism PAN

Tematy:

electrical harmonic estimation
interpolation DFT
triple-line interpolation

Opis:

The discrete Fourier transform (DFT) is a principal method for power system harmonic analysis. The fundamental frequency of the power system increases or decreases following load changes during normal operation. It is difficult to achieve synchronous sampling and integer period truncation in power harmonic analysis. The resulting spectrum leakage affects the accuracy of the measurement results. For this reason, a windowed interpolation DFT method for power system harmonic analysis to reduce errors was presented in this paper. First, the frequency domain expression of the windowed signal Fourier transform is analyzed. Then, the magnitude of the three discrete spectrum lines near the harmonic frequency point is used to determine the accurate position of the harmonic spectrum. Then, the calculation of the amplitude, frequency, and phase of harmonics is presented. The tripleline interpolation DFT can improve the accuracy of electrical harmonic analysis. Based on the algorithm, the practical rectification formulas were obtained by using the polynomial approximation method. The simulation results show that the fast attenuation of window function sidelobe is the key to reduce the error. The triple-line interpolation DFT based on Hanning, Blackman, Nuttall 3-Term windows has higher calculation accuracy, which can meet the requirements of electrical harmonic analysis.

Źródło:

Archives of Electrical Engineering; 2022, 71, 3; 549--558
1427-4221
2300-2506

Pojawia się w:

Archives of Electrical Engineering

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 28.

Tytuł:

Reakcje [2+3] cykloaddycji sprzężonych nitro alkenów w świetle teorii indeksów elektrofilowości
[2+3] cycloaddition reactions of conjugated nitroalkenes in the light of electrophilicity indexes theory

Autorzy:

Dresler, E.
Jasińska, E.
Nowakowska-Bogdan, E.
Jasiński, R.

Powiązania:

https://bibliotekanauki.pl/articles/142989.pdf

Data publikacji:

2015

Wydawca:

Stowarzyszenie Inżynierów i Techników Przemysłu Chemicznego. Zakład Wydawniczy CHEMPRESS-SITPChem

Tematy:

[2+3] cykloaddycja
nitroalkeny
reaktywność
regioselektywność
elektrofilowość
indeksy DFT
cycloaddition reaction [2+3]
nitroalkenes
reactivity
regioselectivity
electrophilicity
DFT indices

Opis:

W pracy – na podstawie danych literaturowych – przedyskutowano możliwość wykorzystania indeksów elektrofilowości do interpretowania przebiegu polarnych [2+3] cykloaddycji. Dyskusję tę przeprowadzono w odniesieniu do reakcji z udziałem sprzężonych nitroalkenów.
In the publication – on the basis of the published literature – the possibility of using electrophilicity indexes for interpretation of the course of the polar [2+3] cycloaddition reactions has been discussed. The analysis is referring to the coupled reaction involving nitroalkenes.

Źródło:

Chemik; 2015, 69, 3; 146-153
0009-2886

Pojawia się w:

Chemik

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 29.

Tytuł:

Bonding xenon and krypton on the surface of uranium dioxide single crystal

Autorzy:

Dąbrowski, L.
Szuta, M.

Powiązania:

https://bibliotekanauki.pl/articles/147310.pdf

Data publikacji:

2014

Wydawca:

Instytut Chemii i Techniki Jądrowej

Tematy:

noble gases
uranium dioxide
chemical bond
DFT
GGA

Opis:

We present density functional theory (DFT) calculation results of krypton and xenon atoms interaction on the surface of uranium dioxide single crystal. A pseudo-potential approach in the generalised gradient approximation (GGA) was applied using the ABINIT program package. To compute the unit cell parameters, the 25 atom super-cell was chosen. It has been revealed that close to the surface of a potential well is formed for xenon and krypton atom due to its interaction with the atoms of oxygen and uranium. Depth and shape of the well is the subject of ab initio calculations in adiabatic approximation. The calculations were performed both for the case of oxygenic and metallic surfaces. It has been shown that the potential well for the oxygenic surface is deeper than for the metallic surface. The thermal stability of immobilising the atoms of krypton and xenon in the potential wells were evaluated. The results are shown in graphs.

Źródło:

Nukleonika; 2014, 59, 3; 83-89
0029-5922
1508-5791

Pojawia się w:

Nukleonika

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 30.

Tytuł:

Spin trapping studies of essential oils in lipid systems

Autorzy:

Makarova, K.
Drązikowska, K.
Suska, B.
Zawada, K.
Wawer, I.

Powiązania:

https://bibliotekanauki.pl/articles/147786.pdf

Data publikacji:

2015

Wydawca:

Instytut Chemii i Techniki Jądrowej

Tematy:

spin trapping ESR
essential oils
DFT calculations
lipids

Opis:

In the present work, we report the results of a spin trapping ESR study of four essential oils widely used for skin care products such as creams and bath salts. The studied essential oils are Rosmarini aetheroleum (rosemary), Menthae piperitae aetheroleum (mint), Lavandulae aetheroleum (lavender), and Thymi aetheroleum (thyme). Fenton reaction in the presence of ethanol was used to generate free radicals. The N-tert- -butyl-α-phenylnitrone (PBN) was used as a spin trap. In the Fenton reaction, the rosemary oil had the lowest effect on radical adduct formation as compared to the reference Fenton system. Since essential oils are known to be lipid soluble, we also conducted studies of essential oils in Fenton reaction in the presence of lipids. Two model lipids were used, namely 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) and 1,2-dipalmitoyl-sn- -glycero-3-phosphocholine (DPPC). The obtained results suggested that in the presence of DOPC lipids, the •OH and PBN/•CHCH3(OH) radicals are formed in both phases, that is, water and lipids, and all the studied essential oils affected the Fenton reaction in a similar way. Whereas, in the DPPC system, the additional type of PBN/X (aN = 16.1 G, aH = 2.9 G) radical adduct was generated. DFT calculations of hyperfi ne splittings were performed at B3LYP/6-311+G(d,p)/EPR-II level of theory for the set of c-centered PBN adducts in order to identify PBN/X radical.

Źródło:

Nukleonika; 2015, 60, No. 3, part 1; 461-468
0029-5922
1508-5791

Pojawia się w:

Nukleonika

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 31.

Tytuł:

Accounts of the new aspects of nitromethane initiation reactivity

Autorzy:

Zeman, S.
Atalar, T.
Friedl, Z.
Ju, X-H.

Powiązania:

https://bibliotekanauki.pl/articles/358898.pdf

Data publikacji:

2009

Wydawca:

Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego

Tematy:

DFT B3LYP methods
detonation
initiation
nitromethane

Opis:

A well-known effect of amines, and also of water, on detonation characteristics of nitromethane (NM) is discussed from the point of view of the published knowledge about the study of initiation reactivity of this nitro paraffin. It is documented that bimolecular and higher interactions during the initiation of NM are impossible. The most widespread concepts of the primary steps of this initiation, i.e. formation of aci-NM anion [CH2=NO2]— by intermolecular hydrogen transfer in the neat NM submitted to shock and formation of this anion by action of an amine, have been scrutinized by the DFT B3LYP/cc-pVTZ+ method and evaluated as thermodynamically disadvantageous. Also the 1,3-intramolecular hydrogen shift in the NM molecule was characterized as a higher-barrier process. Two favorable primary mechanisms of fission in the NM initiation and development of its detonation were investigated by DFT B3LYP/cc-pVTZ+ calculations: homolysis of C–NO2 bond in the neat NM and homolysis of N–OH bond in its aci-form. The second mentioned pathway was found to be thermodynamically the most preferable mechanism of fission. Consequently, a detonation wave of NM with admixture of amine or water has a considerably reduced reaction zone length in comparison with the detonation of neat NM. The B3LYP/6-311++G(d,p) calculations of transition states revealed that an admixture of methylamine and/or water influences the conversion of nitromethane to its aci-form, and this effect is more feasible in the case of methylamine rather than water.

Źródło:

Central European Journal of Energetic Materials; 2009, 6, 1; 119-133
1733-7178

Pojawia się w:

Central European Journal of Energetic Materials

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 32.

Tytuł:

Synthesis, spectral characterization (FT-IR and NMR) and DFT (Molecular structure, HOMO-LUMO, NLO) computational studies on some novel (E)-N-phenyl-3,5-dichloropyridin-4-amine and its derivatives

Autorzy:

Prabhakaran, N. R.
Palanivel, C.

Powiązania:

https://bibliotekanauki.pl/articles/1192697.pdf

Data publikacji:

2016

Wydawca:

Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN

Tematy:

Schiff base
DFT
HOMO-LUMO
Mulliken Charge
MEP

Opis:

A new series of Schiff bases were synthesized for the first time by the condensation of substituted aldehyde and 3,5-dichloropyridin-4-amine in ethanol (1:1). The structure of Schiff bases were experimentally characterized by using IR and 1H NMR spectroscopic methods. The structural and vibrational properties of the studied molecules were investigated theoretically by performing density functional theory (DFT) to access reliable results to the experimental values and the calculation results showed good agreement with the experimental ones. The calculated HOMO and LUMO energies showed that charge transfer occurs within the molecule. Atomic charges and molecular electrostatic potential (MEP) have been calculated at the B3LYP method and standard 6-31G(d,p) basis set starting from optimized geometry.

Źródło:

World Scientific News; 2016, 46; 244-259
2392-2192

Pojawia się w:

World Scientific News

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 33.

Tytuł:

Elastic constants and analytic bond order potential for atomistic simulations of simple cubic tungsten trioxide

Autorzy:

Dendzik, Z.
Chrobak, D.
Nowak, R.

Powiązania:

https://bibliotekanauki.pl/articles/1943224.pdf

Data publikacji:

2009

Wydawca:

Politechnika Gdańska

Tematy:

tungsten trioxide
DFT
elastic constans
bond-order potential

Opis:

A set of elastic constants was calculated and a parametrization of the potential was derived for simple cubic tungsten trioxide based on an analytical bond-order scheme. It was show that the obtained parametrization provided a good description of interatomic forces and such properties as the lattice constant, the bulk modulus and the elastic constants.

Źródło:

TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2009, 13, 1-2; 93-98
1428-6394

Pojawia się w:

TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 34.

Tytuł:

New insights into pyrite-hydrogen peroxide interactions during froth flotation: experimental and DFT study

Autorzy:

Cao, Qinbo
Yan, Wenchao
Wen, Shuming
Liu, Dianwen
Li, Yanjun

Powiązania:

https://bibliotekanauki.pl/articles/2200334.pdf

Data publikacji:

2023

Wydawca:

Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej

Tematy:

hydrogen peroxide
oxidization
pyrite flotation
adsorption models
DFT

Opis:

Hydrogen peroxide (H2O2) is an efficient depressant for pyrite (FeS2) flotation. However, the depressing mechanism of H2O2 is not fully understood. In this paper, the depressing capacity of H2O2 for pyrite was examined by flotation tests. Results revealed that pyrite flotation could be inhibited by H2O2 at pH 6.4. The pyrite powder in H2O2 solution enhanced the release of O2 from H2O2. However, the O2 concentration in the solution was less than that of H2O2; thus, H2O2 is the major oxidant in the solution. Moreover, density functional theory calculations were performed to study the interactions between H2O2 and hydrated pyrite (100) surface. The H2O2 molecule tended to react with the pyrite surface to generate one S=O bond and an H2O molecule. The possible binding models of O2 molecules on the pyrite (100) surface were also studied for comparison. The O2 dissociation on the pyrite surface was more favorable than the adsorption of O2 as a whole. In addition, the orbital interaction in the S=O bond raised from the reaction of H2O2/O2 with the pyrite surface was also investigated by the density states analysis. These results provide some insights into the oxidizing effect of H2O2 in pyrite flotation.

Źródło:

Physicochemical Problems of Mineral Processing; 2023, 59, 1; art. no. 157409
1643-1049
2084-4735

Pojawia się w:

Physicochemical Problems of Mineral Processing

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 35.

Tytuł:

Surface Effect on Electronic, Magnetic and Optical Properties of PtCoBi Half-Heusler: A DFT Study

Autorzy:

Rezazadeh, Hamed
Hantehzadeh, Mohamadreza
Boochani, Arash

Powiązania:

https://bibliotekanauki.pl/articles/2048803.pdf

Data publikacji:

2022

Wydawca:

Polska Akademia Nauk. Czytelnia Czasopism PAN

Tematy:

PtCoBi
[001] film
DFT
electronic property
optical property

Opis:

The electronic, magnetic, and optical properties of PtCoBi half-Heusler compound [001] surfaces and its bulk state have been investigated in the framework of density functional theory using GGA approximation. The half-metallic behaviors of CoBiterm, CoPt-term and PtBi-term decrease with respect to its bulk state. The spin polarization at the Fermi level is 73.2% for the bulk state, and it is -64.4% and -64.1% for the CoBi-term and PtBi-term, respectively while less polarization has been observed for the CoPt-term. All terminations have given almost similar optical responses to light. Plasmon oscillations for the terminations occur in the range of 12.5 to 14.5 eV (21 to 22 eV) along xx (zz), and it occurs at 23 eV for the bulk state. The refractive index for the bulk and all three terminations is very high in the infrared and visible areas, meaning a very strong metallic trend in these compounds. The phenomenon of super-luminance occurs for the incident light with energy exceeding 5.5 eV for all three terminations, and it occurs in the range of 10 eV for the bulk mode. These terminations show transparent behavior after the energy of 10 eV.

Źródło:

Archives of Metallurgy and Materials; 2022, 67, 1; 155-166
1733-3490

Pojawia się w:

Archives of Metallurgy and Materials

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 36.

Tytuł:

Fast one-cycle frequency estimation of a single sinusoid in noise using downsampled linear prediction model

Autorzy:

Duda, Krzysztof
Zieliński, Tomasz P.

Powiązania:

https://bibliotekanauki.pl/articles/2052172.pdf

Data publikacji:

2021

Wydawca:

Polska Akademia Nauk. Czytelnia Czasopism PAN

Tematy:

frequency estimation
linear prediction
Prony method
smart DFT

Opis:

A new solution to the problem of frequency estimation of a single sinusoid embedded in the white Gaussian noise is presented. It exploits, approximately, only one signal cycle, and is based on the well-known 2nd order autoregressive difference equation into which a downsampling is introduced. The proposed method is a generalization of the linear prediction based Prony method for the case of a single undamped sinusoid. It is shown that, thanks to the proposed downsampling in the linear prediction signal model, the overall variance of the least squares solution of frequency estimation is decreased, when compared to the Prony method, and locally it is even close to the Cramér-Rao Lower Bound, which is a significant improvement. The frequency estimation variance of the proposed solution is comparable with, computationally more complex, the Matrix Pencil and the Steiglitz-McBride methods. It is shown that application of the proposed downsampling to the popular smart DFT frequency estimation method also significantly reduces the method variance and makes it even better than the least squares smart DFT. The noise immunity of the proposed solution is achieved simultaneously with the reduction of computational complexity at the cost of narrowing the range of measured frequencies, i.e. a sinusoidal signal must be sufficiently oversampled to apply the proposed downsampling in the autoregressive model. The case of 64 samples per period with downsampling up to 16, i.e. 1/4th of the cycle, is presented in detail, but other sampling scenarios, from 16 to 512 samples per period, are considered as well.

Źródło:

Metrology and Measurement Systems; 2021, 28, 4; 661-672
0860-8229

Pojawia się w:

Metrology and Measurement Systems

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 37.

Tytuł:

Structure-activity of chelating depressants for chalcopyrite/pyrite separation: DFT study and flotation experiment

Autorzy:

Li, Mingyang
Lian, De
Zhao, Fugang
Tong, Xiong
Wu, Chaoyang
Gao, Xiangpeng

Powiązania:

https://bibliotekanauki.pl/articles/2146867.pdf

Data publikacji:

2021

Wydawca:

Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej

Tematy:

chelating depressants
activity
pyrite
DFT calculations
frontier orbitals

Opis:

Three types of chelating depressants were studied for chalcopyrite/pyrite separation, including S-S, S-O, and O-O types, via density functional theory calculations and microflotation. The calculation results indicate that the depressant’s chelating atoms have large coefficient and great activity according to the molecular frontier orbital (HOMO and LUMO) and the orbital coefficients. For S-S type of depressant, S atom in both keto or enol forms won’t affect their HOMO and LUMO patterns and the orbital contributions. For S-O type, the presence of N atom in the ring structure of a molecular will increase the reactivity of O-Cu while weak S-Cu. For O-O type, the electron supply capacity of benzene ring is higher than strain chain, and atom N in strain chain increased their electron supply capacity. The microflotation results basically confirmed the prediction based on the calculation. The simulation results demonstrate that the interaction of a depressant with metals and minerals are affected obviously by the spatial structure and electronic structure of an atom in its molecular.

Źródło:

Physicochemical Problems of Mineral Processing; 2021, 57, 6; 102--112
1643-1049
2084-4735

Pojawia się w:

Physicochemical Problems of Mineral Processing

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 38.

Tytuł:

Błędy metody LIDFT dla klasycznych okien danych
Errors of the LIDFT method for classic data windows

Autorzy:

Borkowski, J.
Mroczka, J.

Powiązania:

https://bibliotekanauki.pl/articles/153710.pdf

Data publikacji:

2007

Wydawca:

Stowarzyszenie Inżynierów i Techników Mechaników Polskich

Tematy:

uzupełnianie zerami
interpolacja DFT
analiza sygnału wieloczęstotliwościowego
estymacja widma
LIDFT
padding zeros
DFT interpolation
multi-frequncy signal analysis
spectrum estimation

Opis:

Praca przedstawia rozwinięcie metody liniowej interpolacji dyskretnego przekształcenia Fouriera (LIDFT) wykorzystujące klasyczne okna danych oraz technikę uzupełniania zerami, dobrze znane z analizy widma z użyciem algorytmu FFT. Wykorzystanie klasycznych okien danych w miejsce specjalnie dedykowanego dla metody LIDFT okna parametrycznego daje bardziej różnorodne możliwości wykorzystania metody LIDFT w analizie sygnału wieloczęstotliwościowego.
Development of the discrete Fourier transform linear interpolation method (LIDFT) with using classical data windows and zero padding technique well-known from spectrum analysis with FFT is presented in the paper. Using classical data windows instead of parametric data window special dedicated for LIDFT method gives wide-range possibilities of the using LIDFT method in the multifrequency signal analysis.

Źródło:

Pomiary Automatyka Kontrola; 2007, R. 53, nr 9 bis, 9 bis; 108-111
0032-4140

Pojawia się w:

Pomiary Automatyka Kontrola

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 39.

Tytuł:

A DFT study of reorganization energy of some chosen carbazole derivatives
Obliczenia DFT energii reorganizacji dla wybranych pochodnych karbazolu

Autorzy:

Kania, Sylwester
Kościelniak-Mucha, Barbara
Kuliński, Janusz
Słoma, Piotr
Wojciechowski, Krzysztof

Powiązania:

https://bibliotekanauki.pl/articles/2022175.pdf

Data publikacji:

2020

Wydawca:

Politechnika Łódzka. Wydawnictwo Politechniki Łódzkiej

Tematy:

reorganization energy
DFT calculations
benzocarbazoles
Marcus-Hush theory of electron transport
energia reorganizacji
obliczenia DFT
benzokarbazole
teoria transferu elektronów Marcusa-Husha

Opis:

Strong efforts toward finding an organic semiconductor with a molecule characterized by a low charge transfer energy applying quantum-chemical calculations are undertaken. Density Functional Theory (DFT) calculations made for carbazole (Cz) and three isomers of benzocarbazole, benzo (a) carbazole (BaCz), benzo (b) carbazole (BbCz) and benzo (c) carbazole (BcCz) proves the possibility of lacking the growth of reorganization energy despite the molecule dimentions enlargement. Benzo(b)carbazole molecules with high longitudinal dimension of the rigid skeleton d = 9,05 Å posses the low value of reorganization energy for both hole and electron transport of 0,18 eV and 0,11 eV, respectively. We suggest that the reduction of reorganization energy may be related to the diminishing of intramolecular hydrogen interactions.
W artykule przedstawiono wyniki obliczeń kwantowo-mechanicznych mających na celu poszukiwanie cząsteczki organicznego półprzewodnika charakteryzującego się niską energią transferu ładunku. Obliczenia z wykorzystaniem teorii funkcjonału gęstości (DFT) zostały wykonane dla karbazolu (Cz) i trzech izomerów benzokarbazolu, benzo(a)karbazolu (BaCz) , benzo(b)karbazolu (BbCz) i benzo(c)karbazolu (BcCz) dowodzą , że można uniknąć wzrostu energii reorganizacji cząsteczki tak dla przewodnictwa dziurowego jak i dla przewodnictwa elektronowego pomimo zwiększenia rozmiarów przestrzennych szkieletu aromatycznego cząsteczki. Cząsteczki benzo(b)karbazolu o największym rozmiarze podłużnym szkieletu d = 9,05 Å charakteryzują się najniższą energią reorganizacji dla przewodnictwa dziur λh = 0,18 eV oraz najniższą wśród izomerów benzokarbazolu energią reorganizacji dla przewodnictwa elektronowego λe = 0,11 eV. Analiza odległości pomiędzy wybranymi charakterystycznymi atomami wodoru pozwala przypuszczać, że zmniejszenie energi reorganizacji obserwowane dla benzo(b)- karbazolu jest związane ze zmiejszaniem wewnątrzcząsteczkowych oddziaływań pomiędzy sąsiadującymi atomami wodoru.

Źródło:

Scientific Bulletin. Physics / Technical University of Łódź; 2020, 41; 33-42
1505-1013
2449-982X

Pojawia się w:

Scientific Bulletin. Physics / Technical University of Łódź

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 40.

Tytuł:

Synthesis, Characterization and DFT Calculations of 4-((2-Hydroxyethyl)imino)naphthalen-1(4H)-One and its Cu(II) Complex

Autorzy:

Gorgulu, G.
Dede, B.

Powiązania:

https://bibliotekanauki.pl/articles/1029785.pdf

Data publikacji:

2018-02

Wydawca:

Polska Akademia Nauk. Instytut Fizyki PAN

Tematy:

Schiff base
quinone
metal complex
spectroscopy
copper(II)
DFT

Opis:

We have reported herein the synthesis of a novel quinone derivative ligand containing the Schiff base and its Cu(II) complex starting from 1,4-naphthoquinone. Synthesized compounds were characterized using the Fourier transform infrared, UV-Vis, elemental analysis, inductively coupled plasma optical emission spectrometry, molar conductivity, and magnetic susceptibility measurements. The free ligand was also characterized by ¹H- and ¹³C-NMR spectra. Elemental analyses, stoichiometric and spectroscopic data indicated that the metal:ligand ratio is 1:2 and octahedral structure is proposed for the metal complex of the Schiff base ligand. Computational quantum calculations were also performed using DFT/B3LYP level of theory with 6-311++G(d,p) basis set for the synthesized ligand. It was found that the experimental and theoretical spectroscopic data were consistent.

Źródło:

Acta Physica Polonica A; 2018, 133, 2; 239-243
0587-4246
1898-794X

Pojawia się w:

Acta Physica Polonica A

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 41.

Tytuł:

Spectroscopic Properties and Quantum Chemical Calculations of Novel Diimine Molecules and their Mononuclear Cu(II) Complexes

Autorzy:

Dede, B.
Gorgulu, G.

Powiązania:

https://bibliotekanauki.pl/articles/1029792.pdf

Data publikacji:

2018-02

Wydawca:

Polska Akademia Nauk. Instytut Fizyki PAN

Tematy:

Schiff base
diimine
metal complex
spectroscopy
copper(II)
DFT

Opis:

Two novel Schiff base ligands, 2,2'-((pentane-2,4-diylidene)bis(azanylylidene))bis(4-chlorophenol) and 2,2'-((pentane-2,4-diylidene)bis(azanylylidene))bis(4-methylphenol) were prepared by condensation reaction of acetylacetone with 2-amino-4-chlorophenol and 2-amino-4-methylphenol, respectively. Mononuclear Cu(II) complex of each ligand was also synthesized. These compounds were characterized by elemental analyses, inductively coupled plasma optical emission spectrometry, the Fourier transform infrared spectra, UV-Vis, molar conductivity, and magnetic susceptibility measurements. The ligands have been further characterized by ¹H- and ¹³C-NMR. The results suggest that the metal complexes of the ligands have a metal:ligand ratio of 1:1 and the Cu(II) ions are coordinated by the phenolic oxygen atoms and imine nitrogen atoms of the ligands. Moreover, the quantum chemical calculations of the compounds have been performed using the density functional theory. It has been found that the calculated spectroscopic values are in a good agreement with experimental data.

Źródło:

Acta Physica Polonica A; 2018, 133, 2; 256-262
0587-4246
1898-794X

Pojawia się w:

Acta Physica Polonica A

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 42.

Tytuł:

A DFT study or the relationship between the electronic structure and the antiplasmodial activity of a series of 4-anilino-2-trichloromethylquinazolines derivatives

Autorzy:

Anatovi, Wilfried
Kpotin, Gaston A.
Kuevi, Urbain A.
Houngue-Kpota, Alice
Atohoun, Guy S.
Mensah, Jean-Baptiste
Gómez-Jeria, Juan S.

Powiązania:

https://bibliotekanauki.pl/articles/1178269.pdf

Data publikacji:

2017

Wydawca:

Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN

Tematy:

4-anilino-2-trichloromethylquinazolines
DFT
KPG method
QSAR
antiplasmodial

Opis:

A theoretical study of the relationships between the electronic structure and the antiplasmodial activity of a series of 4-anilino-2-trichloromethylquinazolines derivatives on plasmodium genes was carried out. The electronic structure of molecules was calculated at the B3LYP/6-31G(d,p) level with full geometry optimization. A statistically significant equation (R = 0.98, R² = 0.96, adj-R² = 0.94, F (12, 20) = 43.49 (p < 0.000001) and SD = 0.12) was obtained relating the variation of the biological activity with the variation of a set of local atomic reactivity indices. Based on the analysis of the results, a two-dimensional antiplasmodial pharmacophore was proposed. The process seems to be orbital and charge controlled.

Źródło:

World Scientific News; 2017, 88, 2; 138-151
2392-2192

Pojawia się w:

World Scientific News

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 43.

Tytuł:

Theoretical study of the effect the hydroxyl subgroups on the electronic properties of iso-indene molecule

Autorzy:

Obayes, Abbas Ibrahim
Hasan, Nahida B.
Aboud, Hamed Ibrahem
Mohammed, Mohammed Ahmed

Powiązania:

https://bibliotekanauki.pl/articles/1191969.pdf

Data publikacji:

2016

Wydawca:

Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN

Tematy:

DFT
energy gap
ionization potential
hardness and IR-spectrum

Opis:

In this work, six molecules model are optimized at B3LYP/6-31G** density functional theory. Electronic properties of iso-indene molecules were investigated depending on the three parameters (B3LYP) by density functional theory method. The best geometry for all molecules were investigated at (6-31G**) basis sets. The total energies, energy gaps, ionization potentials, electron affinities and softness were calculated for the studied molecules. Adding the (OH) ion and Nitrogen, Sulfur atoms to the iso-indene molecules leads to decrease the energy gap and the hardness of the studied molecules. The IR-spectra shows the effect of adding the (OH) ion and Nitrogen, Sulfur atoms in the ring on the vibrations of the reference molecule, the electronic properties and IR spectrum for all molecules were investigated by Gaussian 03 program.

Źródło:

World Scientific News; 2016, 50; 49-63
2392-2192

Pojawia się w:

World Scientific News

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 44.

Tytuł:

Polarization of organic aromatic molecule in anionic and cationic state
Polaryzacja cząsteczki aromatycznej w stanie anionu i kationu

Autorzy:

Kania, Sylwester
Kościelniak-Mucha, Barbara
Kuliński, Janusz
Słoma, Piotr
Wojciechowski, Krzysztof

Powiązania:

https://bibliotekanauki.pl/articles/952821.pdf

Data publikacji:

2019

Wydawca:

Politechnika Łódzka. Wydawnictwo Politechniki Łódzkiej

Tematy:

DFT
anthraquinone
anthrone
charge transport
antrachinon
antron
transport ładunku

Opis:

The modification of electron states and the change in the geometry of the structure of molecule during hopping transport of charge carriers depends on the symmetry of the molecule. During electric transport the molecule reversibly transforms from neutral state to cation when hole conductivity occurs or to anion when electron conductivity occurs. The energies of orbitals HOMO and HOMO-1 of anthrone and anthrachinone are always negative, what allows for holes transport. Positive energies of LUMO and LUMO+1 orbitals of anion of anthrone and anthraquinone in structure of anion or neutral molecule make electron transport difficult.
Wyniki obliczeń jednoznacznie wskazują na dużą stabilność kationów antrachinonu i antronu. Realizacja przewodnictwa dziur jest w tej sytuacji możliwa dla obu materiałów. Wysoka dodatnia wartość poziomów LUMO i LUMO+1 dla antrachinonu powyżej 1,8 eV nie pozwala na uzyskanie stabilnego przewodzenia elektronów w fazie stałej antrachinonu. Jednak ujemna wartość poziomu HOMO dla anionu pozwala na przejście cząsteczki w fazie stałej do podstawowego poziomu anionu w stanie jonizacji +1. Pozwala to na wykorzystanie antrachinonu w postaci fazy stałej dla potrzeb technologii wykorzystującej środowisko elektrochemiczne. Wysoka wartość dodatnia poziomów HOMO oraz LUMO i LUMO +1 dla anionu antronu utrudnia uzyskanie efektywnego przewodzenia elektronów dla zastosowań w technologii elektroniki organicznej. Jednak dzięki posiadaniu podstawnika, własności anionu antronu są korzystniejsze dla zastosowań niż własności anionu niepodstawionego antracenu. Pomimo podobieństwa cząsteczek i struktur, w jakich krystalizują, występuje znacząca różnica w wartości przerwy energetycznej Eg pomiędzy antronem i antrachinonem. Uzyskane wyniki wskazują na inne obszary możliwych zastosowań antrachinonu i antronu w elektronice organicznej. Wysoka wartość energii przerwy zabronionej może być korzystna dla zastosowań obu materiałów do wytwarzania warstw aktywnych w komórkach słonecznych, gdzie wymagana jest wysoka rezystywność ze względu na konieczność rozdziału generowanych ładunków.

Źródło:

Scientific Bulletin. Physics / Technical University of Łódź; 2019, 40; 27-35
1505-1013
2449-982X

Pojawia się w:

Scientific Bulletin. Physics / Technical University of Łódź

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 45.

Tytuł:

Zastosowanie teorii funkcjonałów gęstości do modelowania właściwości elektronowych skorpionianowych kompleksów oksodimolibdenowych
Application of density functional theory in model ling of electron properties of oxodimolybdenum scorpionate complexes

Autorzy:

Romańczyk, P.
Brocławik, E.

Powiązania:

https://bibliotekanauki.pl/articles/1286504.pdf

Data publikacji:

2011

Wydawca:

Stowarzyszenie Inżynierów i Techników Przemysłu Chemicznego. Zakład Wydawniczy CHEMPRESS-SITPChem

Tematy:

modelowanie DFT
kompleksy skorpionianowe
kompleksy dwurdzeniowe
transfer elektronu
funkcjonalne materiały molekularne
DFT modelling
scorpionate complexes
binuclear complexes
electron transfer
functional molecular materials

Opis:

W artykule, na przykładzie skorpionianowych kompleksów oksodimolibdenowych o mieszanej walencyjności, przedstawiono zastosowanie modelowania DFT do określenia i interpretacji fizycznej wpływu wzajemnej orientacji grup [MoII,INO]3+,2+ (par donorowo- akceptorowych, D-A) na przepływ gęstości elektronowej we fragmencie Mo-O-Mo. Zależność struktury elektronowej, tj. lokalizacji/ delokalizacji niesparowanego elektronu od wzajemnego położenia lokalnych układów współrzędnych D i A, może nadawać kompleksom właściwości molekularnych przełączników i reostatów.
This paper presents the application of DFT modelling in the determination and physical interpretation of the effect of mutual orientation of [MoII, INO] 3+,2+ groups (donor-acceptor pairs, D-A) on the electron density flow in the Mo-O-Mo moiety, exemplified by oxodimolybdenum scorpionate complexes of mixed valence. The relationship between the electron structure, i.e. localization/ delocalization of unpaired electron and mutual position of D and A coordinate systems, may bestow the properties of molecular switches and rheostats on complexes.

Źródło:

Chemik; 2011, 65, 10; 1093-1100
0009-2886

Pojawia się w:

Chemik

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 46.

Tytuł:

Vibrational Spectroscopic and Computational Studies on Bis(2-aminopyridinium)fumarate - Fumaric Acid (1:1) Complex

Autorzy:

Kanagathara, N.
Pawlus, K.
Marchewka, M.

Powiązania:

https://bibliotekanauki.pl/articles/1029823.pdf

Data publikacji:

2018-01

Wydawca:

Polska Akademia Nauk. Instytut Fizyki PAN

Tematy:

2-aminopyridine
fumaric acid
DFT
FT-IR
FT-Raman

Opis:

The new vibrational and computational studies on bis(2-aminopiridinium) fumarate - fumaric acid (1:1) complex have been made. The molecular geometry, vibrational frequencies and intensities of vibrational bands have been interpreted with the aid of structure optimization based on density functional theory (B3LYP) method with 6-311++G(d,p) basis set. The highly occupied-lowly unoccupied molecular orbital energies and chemical reactivity of the molecule have been calculated with time-dependent density functional theory approach. Stability energies of the molecule have been studied using natural bond orbital analysis. The predicted nonlinear optical properties of the title compound are much greater that those of urea. In addition, the molecular electrostatic potential surfaces and thermodynamic properties were calculated.

Źródło:

Acta Physica Polonica A; 2018, 133, 1; 45-56
0587-4246
1898-794X

Pojawia się w:

Acta Physica Polonica A

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 47.

Tytuł:

Atomic scale study of silver sulfide leaching with cyanide and thiourea

Autorzy:

Bernaola-Flores, Roxana
Silva-Quiñones, Dhamelyz
Balbuena, Perla B.
Rodríguez-Reyes, Juan Carlos F.
Tarazona-Vasquez, Francisco

Powiązania:

https://bibliotekanauki.pl/articles/109763.pdf

Data publikacji:

2019

Wydawca:

Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej

Tematy:

leaching
cyanidation
thioureation
DFT
cluster models
Ag2S

Opis:

Understanding of atomic scale interactions of molecular species with mineral surfaces is needed to bring about mineral processing innovation. In this regard, Density Functional Theory (DFT) methods are well suited. In this work, the outcome of leaching synthetic acanthite –a surrogate for a silver-containing sulfide ore- with both cyanide ion and thiourea are studied with DFT considering solvent effects. The results are correlated to the experimental percentage of silver extracted with each of the leaching agents under similar conditions of molar concentration, temperature and percentage of solids. Our calculations show both leaching reactions to be exergonic and of the same order of magnitude in Gibbs energy of reaction than values determined from thermodynamic tables. Also, less favorable Gibbs reaction energies are obtained for cyanidation in absence of oxygen and thioureation in absence of Fe(II) highlighting the impact of oxidants on the exergonicity of the respective global leaching reactions. Finally, analyzing the percentage of silver extracted from acanthite and the absolute value of Gibbs energies of the respective reaction, we conclude that the more exergonic a leaching reaction, the higher percentage of silver is extracted from acanthite, provided that there is no kinetic control of each of the leaching reactions.

Źródło:

Physicochemical Problems of Mineral Processing; 2019, 55, 4; 969-980
1643-1049
2084-4735

Pojawia się w:

Physicochemical Problems of Mineral Processing

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 48.

Tytuł:

Thermodynamic Phase Diagram and Phonon stability, Electronic and Optical Properties of FeVSb: A DFT study

Autorzy:

Bagheri, A.
Boochani, A.
Masharian, S. R.
Jafarpour, F. H.

Powiązania:

https://bibliotekanauki.pl/articles/2203753.pdf

Data publikacji:

2023

Wydawca:

Polska Akademia Nauk. Czytelnia Czasopism PAN

Tematy:

DFT
thermodynamic phase diagram
phonon
electronic properties
optical properties

Opis:

Mechanical, electronic, thermodynamic phase diagram and optical properties of the FeVSb half-Heusler have been studied based on the density functional theory (DFT) framework. Studies have shown that this structure in the MgAgAs-type phase has static and dynamic mechanical stability with high thermodynamic phase consistency. Electronic calculations showed that this compound is a p-type semiconductor with an indirect energy gap of 0.39 eV. This compound’s optical response occurs in the infrared, visible regions, and at higher energies its dielectric sign is negative. The Plasmon oscillations have occurred in 20 eV, and its refraction index shifts to zero in 18 eV.

Źródło:

Archives of Metallurgy and Materials; 2023, 68, 1; 331--338
1733-3490

Pojawia się w:

Archives of Metallurgy and Materials

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 49.

Tytuł:

Discrete Fourier transform based pattern classifiers

Autorzy:

Hui, S.
Żak, S. H.

Powiązania:

https://bibliotekanauki.pl/articles/202074.pdf

Data publikacji:

2014

Wydawca:

Polska Akademia Nauk. Czytelnia Czasopism PAN

Tematy:

pattern classification
multidimensional discrete Fourier transform
DFT
Fourier coefficients

Opis:

A technique for pattern classification using the Fourier transform combined with the nearest neighbor classifier is proposed. The multidimensional fast Fourier transform (FFT) is applied to the patterns in the data base. Then the magnitudes of the Fourier coefficients are sorted in descending order and the first P coefficients with largest magnitudes are selected, where P is a design parameter. These coefficients are then used in further processing rather than the original patterns. When a noisy pattern is presented for classification, the pattern’s P Fourier coefficients with largest magnitude are extracted. The coefficients are arranged in a vector in the descending order of their magnitudes. The obtained vector is referred to as the signature vector of the corresponding pattern. Then the distance between the signature vector of the pattern to be classified and the signature vectors of the patterns in the data base are computed and the pattern to be classified is matched with a pattern in the data base whose signature vector is closest to the signature vector of the pattern being classified.

Źródło:

Bulletin of the Polish Academy of Sciences. Technical Sciences; 2014, 62, 1; 15-22
0239-7528

Pojawia się w:

Bulletin of the Polish Academy of Sciences. Technical Sciences

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 50.

Tytuł:

Antibacterial, DNA photocleavage and molecular docking studies of newly prepared Schiff-based macrocyclic complexes

Autorzy:

Mishra, Purti
Sethi, Pooja
Kumar Ramasamy, Selva
Saini, Adesh K.
Singh Tuli, Hardeep
Mittal, Divya
Trehan, Aarti

Powiązania:

https://bibliotekanauki.pl/articles/40422849.pdf

Data publikacji:

2024-03-30

Wydawca:

Uniwersytet Rzeszowski. Wydawnictwo Uniwersytetu Rzeszowskiego

Tematy:

anti-bacterial
DFT
DNA photocleavage
molecular docking
template method

Opis:

Introduction and aim. At present, several microbial diseases are prominent and of concern worldwide. The intent of this study was to examine the antibacterial potential of newly synthesized tetradentate macrocyclic complexes against different bacterial strains. The macrocyclic scaffold has gained attention as a biologically active class of supramolecular chemistry due to its unique properties and ability to target various microorganisms. Thus, the goal of the present study was to develop a series of biologically active transition metal-based macrocycles. Material and methods. All macrocyclic compounds were synthesized by a template method and validated by molar conductivity, elemental studies, and spectral and magnetic studies. Antibacterial activities of all metal complexes were evaluated against Escherichia coli (MTCC 739) and Staphylococcus aureus (MTCC 731) bacterial strains by taking ampicillin as a standard reference drug. DNA photocleavage potential was explored using agarose gel electrophoresis. Results. Results revealed the formation of novel macrocyclic complexes via tetra nitrogen bond trapping of metals. Copper complexes have strong potential against S. aureus bacteria as copper and nickel both show good DNA photocleavage potential. Conclusion. The findings endorse the biomedical relevance of these macrocyclic scaffolds, suggesting avenues for further exploration in targeted drug delivery and potential clinical applications. The proposed octahedral geometry for the complexes enhances our understanding of their structural aspects. This research contributes substantively to the field, laying the foundation for future investigations in advanced antimicrobial design and application.

Źródło:

European Journal of Clinical and Experimental Medicine; 2024, 22, 1; 154-163
2544-2406
2544-1361

Pojawia się w:

European Journal of Clinical and Experimental Medicine

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 51.

Tytuł:

DFT study of chemical reactivity of free radicals ABTS°+ and DPPH° by Myricetin, Quercetin and Kaempferol

Autorzy:

Houngue, M. T. A. Kpota
Doco, R. Chabi
Kpotin, Gaston A.
Kuevi, Urbain A.
Simplice, Koudjina
Wilfried, Kanhounnon
Atohoun, Y. G. S.
Mensah, Jean-Baptiste

Powiązania:

https://bibliotekanauki.pl/articles/1178805.pdf

Data publikacji:

2017

Wydawca:

Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN

Tematy:

B3LYP
DFT
M05-2X
antioxidant activity

Opis:

Myricetin, quercetin and kaempferol are polyphenols belong to the group of flavonoids. They are known for their many biological activities and particularly their strong ability to trap free radicals that cause nuisance to living organisms. In order to rationalize and compare the antioxidant activities of these molecules, DFT study was conducted in the gas phase, at B3LYP / 6-311G (d, p) and M05-2X / 6-311G (d, p). approximation levels. Calculations carried out relate to electronic affinity EA, ionization energy IP, energy gap (HOMO-LUMO), hardness (η), softness (S), electronegativity (χ), electrophilic index (ω) and energy parameters. Results of various calculations compared to those of trolox, molecule identified in our previous work as reference for study antioxidant properties of bioactive molecules have shown that: The three molecules are good antioxidants and could be effective to fight the oxidative attacks of living organisms; The hydroxyl groups of catechol group and C2 = C3 double bond are determinant for the antioxidant activity of the three molecules; Myricetin is the most antioxidant among the three molecules followed by quercetin; The radical ABTS°+ is more suitable for studying the antioxidant properties of molecules.

Źródło:

World Scientific News; 2017, 90; 177-188
2392-2192

Pojawia się w:

World Scientific News

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 52.

Tytuł:

Frequency synchronization error correction by using DFT in sinusoidal voltage measurements

Autorzy:

Krajewski, M.

Powiązania:

https://bibliotekanauki.pl/articles/114200.pdf

Data publikacji:

2016

Wydawca:

Stowarzyszenie Inżynierów i Techników Mechaników Polskich

Tematy:

correction of synchronization error
accurate RMS voltage measurement
DFT algorithm

Opis:

The paper presents a method of correcting a frequency synchronization error in the sinusoidal voltage measurement. Correction is performed by changing a frequency of the measured signal on the basis of the respectively determined synchronization error by using DFT. Carried out simulation experiments indicate that the correction can theoretically improve the accuracy of measurement of the RMS voltage to the level below 1 ppm. The results of measurements taken by a highly accurate voltmeter Agilent 3458 confirm the conclusions of the simulation, that it is possible to repeatedly reduce the frequency synchronization error by applying the developed correction method in the voltage measurement.

Źródło:

Measurement Automation Monitoring; 2016, 62, 7; 218-220
2450-2855

Pojawia się w:

Measurement Automation Monitoring

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 53.

Tytuł:

Investigation on different behavior and mechanism of Ca(II) and Fe(III) adsorption on spodumene surface

Autorzy:

Yu, F.
Wang, Y.
Wang, J.
Xie, Z.

Powiązania:

https://bibliotekanauki.pl/articles/110230.pdf

Data publikacji:

2014

Wydawca:

Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej

Tematy:

spodumene surface
calcium ions
iron ions
adsorption mechanism
DFT calculation

Opis:

Behavior and mechanism of Ca2+ and Fe3+ adsorption on spodumene surface were investigated by micro flotation tests, zeta potential measurements, and density functional theory (DFT) calculation methods. The micro flotation tests showed that Ca2+ and Fe3+ activated the flotation of spodumene remarkably. However, the effect of Fe3+ was more significant than that of Ca2+. Additionally, Fe3+ significantly changed the zeta potential of spodumene while Ca2+ showed a little change. Meanwhile, the calculated adsorption energy of Fe3+ on spodumene surface was much greater than that of Ca2+ indicating that Fe3+ is more apt to be adsorbed on spodumene surface than Ca2+. The value of bond population in Ca-O illustrated that the bond of Ca-O consists of partial covalent proportion and some ionic component. On the contrary, the bond of Fe-O showed a relatively strong covalent property. The partial density of states (PDOS) of free Ca/Fe and the reacted O atom on spodumene (110) surface before and after the adsorption showed that Fe 3d orbital and O 2p orbital formed hybridization. The density of states (DOS) near the Fermi level of spodumene surface after adsorption with Fe3+ was much stronger than that with Ca2+.

Źródło:

Physicochemical Problems of Mineral Processing; 2014, 50, 2; 535-550
1643-1049
2084-4735

Pojawia się w:

Physicochemical Problems of Mineral Processing

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 54.

Tytuł:

Minimization of maximum errors in universal approximation of the unit circle by a polygon

Autorzy:

Borkowski, J.

Powiązania:

https://bibliotekanauki.pl/articles/221779.pdf

Data publikacji:

2011

Wydawca:

Polska Akademia Nauk. Czytelnia Czasopism PAN

Tematy:

unit circle
approximation by polygon
LIDFT
interpolated DFT
zero padding

Opis:

This paper presents a universal approximation of the unit circle by a polygon that can be used in signal processing algorithms. Optimal choice of the values of three parameters of this approximation allows one to obtain a high accuracy of approximation. The approximation described in the paper has a universal character and can be used in many signal processing algorithms, such as DFT, that use the mathematical form of the unit circle. One of the applications of the described approximation is the DFT linear interpolation method (LIDFT). Applying the results of the presented paper to improve the LIDFT method allows one to significantly decrease the errors in estimating the amplitudes and frequencies of multifrequency signal components. The paper presents the derived formulas, an analysis of the approximation accuracy and the region of best values for the approximation parameters.

Źródło:

Metrology and Measurement Systems; 2011, 18, 3; 391-402
0860-8229

Pojawia się w:

Metrology and Measurement Systems

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 55.

Tytuł:

Effect of Vacancies on Electronic and Magnetic Properties of Hydrogen Passivated Graphene Nanoribbons

Autorzy:

Haffad, S.
Benchallal, L.
Lamiri, L.
Boubenider, F.
Zitoune, H.
Kahouadji, B.
Samah, M.

Powiązania:

https://bibliotekanauki.pl/articles/1030793.pdf

Data publikacji:

2018-05

Wydawca:

Polska Akademia Nauk. Instytut Fizyki PAN

Tematy:

DFT
vacancies
AGNR
magnetic
passivated
electronic
charge transfer
band structure

Opis:

Using first-principles calculations we have demonstrated that electronic and magnetic properties of armchair graphene nanoribbons are modified by introducing vacancies defects. The equilibrium geometries, electronic, charge spin density distributions, electronic band structures, and magnetic moments were examined in the presence of vacancies. We have found that introducing vacancies into armchair graphene nanoribbons changes the spatial distribution of neighbor atoms, particularly those located around the vacancies. Our calculations showed that the vacancies have significant effect on the magnetization of armchair graphene nanoribbons. Magnetic moment values and electronic behavior in different configurations depend on the number of vacancies. These results suggest that vacancy defects can be used to modify the electronic and the magnetic properties of armchair graphene nanoribbons.

Źródło:

Acta Physica Polonica A; 2018, 133, 5; 1307-1313
0587-4246
1898-794X

Pojawia się w:

Acta Physica Polonica A

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 56.

Tytuł:

The dependence of dental caries on oral hygiene habits in preschool children from urban and rural areas in Poland

Autorzy:

Kamińska, Aneta
Szalewski, Leszek
Batkowska, Justyna
Wallner, Jan
Wallner, Eliza
Szabelska, Anna
Borowicz, Janusz

Powiązania:

https://bibliotekanauki.pl/articles/987122.pdf

Data publikacji:

2016

Wydawca:

Instytut Medycyny Wsi

Tematy:

dental caries
preschool children
dental health
hygiene practices
dft index

Opis:

Introduction. Dental caries is considered to be a modern civilization disease;however, the state of oral health negatively influences psychological and sociological relations in children which leads to feelings of discomfort from early age. Objective. The aim of study was evaluation of the association between incidence of dental caries (d3ft index) in preschool children from urban and rural areas, and determining the relationship between dental caries intensity and hygienic habits. Materials and Method. 844 children aged 3–6 years from the city and the countryside were examined. The survey was conducted among parents/care givers regarding dental care of children. With parents’ consent, the children had a dental examination. Results. The incidence of caries was recorded at the level of 52.61%, with an average value of 4.31 on the d3ft index; however, for the children from the urban area this ratio amounted to 4.15, and in the countryside it reached the value of 4.7. A correlation was found between age and area of residence of the children and various components of hygienic behavior model. Conclusions. More than a half of the children had dental caries in combination with a high frequency of unsatisfactory hygiene needs. There is a relationship between oral hygiene habits and age of the children, depending on the place of residence.

Źródło:

Annals of Agricultural and Environmental Medicine; 2016, 23, 4
1232-1966

Pojawia się w:

Annals of Agricultural and Environmental Medicine

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 57.

Tytuł:

Application of MoO3 as an efficient catalyst for wet air oxidation treatment of pharmaceutical wastewater (Experimental and DFT study)

Autorzy:

Chen, Chen
Cheng, Ting
Wang, Lei
Tian, Yuan
Deng, Qin
Shi, Yisu

Powiązania:

https://bibliotekanauki.pl/articles/1845416.pdf

Data publikacji:

2021

Wydawca:

Polska Akademia Nauk. Czytelnia Czasopism PAN

Tematy:

wet air oxidation
catalytic wet air oxidation
pharmaceutical wastewater
DFT

Opis:

In this work, a highly effective catalyst (MoO3) is synthesized and applied for catalytic wet air oxidation (CWAO) treatment of pharmaceutical wastewater. The catalyst is systematically characterized to investigate the morphology, crystal structure and chemical composition, and the findings demostrated that MoO3 catalyst is successfully synthesized. The degradation mechanism is also illustrated by the density functional theory (DFT) calculation. The degradation experiments confirm that MoO3 catalyst exhibits excellent catalytic performance in CWAO, and the removal rate of TOC (Total Organic Carbon) and COD (Chemical Oxygen Demand) is achieved to more than 93%. The catalyst doses, reaction temperature and reaction time have a significant impact on the removal of pollutants. The degradation process of pollutants in CWAO could be satisfactorily fitted by the second-order kinetics. Besides, MoO3 displays a favorable stability as CWAO catalyst. DFT calculation illustrates that MoO3 catalyst is a typical indirect band gap semiconductor. Moreover, the high temperature environment provides the thermal excitation energy, which favors to the free electrons nearing Fermi level to escape the material surface, and excites them to the conduction band, then directly reduces the pollutants in CWAO. These findings demonstrate that MoO3 can be used as an efficient and excellent catalyst for CWAO of pharmaceutical wastewater.

Źródło:

Archives of Environmental Protection; 2021, 47, 2; 47-60
2083-4772
2083-4810

Pojawia się w:

Archives of Environmental Protection

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 58.

Tytuł:

Enhancement of Thermoelectric Efficiency and Optical Properties of Hydrogen Absorption in SiC:Mn Nanotube

Autorzy:

Shahraki, Amir Toofani
Gol, Heydar Ali Shafiei
Kimiagar, Salimeh
Dehnavi, Naser Zare

Powiązania:

https://bibliotekanauki.pl/articles/2106575.pdf

Data publikacji:

2022

Wydawca:

Polska Akademia Nauk. Czytelnia Czasopism PAN

Tematy:

DFT
SiC:Mn-H NT
electronic property
thermometric
optical property

Opis:

The effects of hydrogen absorption and manganese substitution on structural, electronic, optical, and thermoelectric properties of silicon-carbon nanotubes (SiCNT) are studied using the density functional theory and the GGA approximation. An examination of the PDOS curves and the electronic band structure showed that the Mn substitution leads to an increase in magnetic anisotropy and the occurrence of semi-metallic behavior and that the hydrogen absorption shifts the band gap toward the lower energies. A study of these nanostructures’ thermoelectric behavior reveals that the H absorption leads to a significant escalation in the figure of merit of the SiCNT to about 1.6 in the room temperature range. The effects of the H absorption on this nanotube’s optical properties, including the dielectric functions and its absorption spectra, are also investigated.

Źródło:

Archives of Metallurgy and Materials; 2022, 67, 2; 397--403
1733-3490

Pojawia się w:

Archives of Metallurgy and Materials

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 59.

Tytuł:

Estimation of the amplitude square using the interpolated Discrete Fourier Transform

Autorzy:

Lušin, T.
Agrež, D.

Powiązania:

https://bibliotekanauki.pl/articles/220579.pdf

Data publikacji:

2011

Wydawca:

Polska Akademia Nauk. Czytelnia Czasopism PAN

Tematy:

estimation
amplitude square
spectral data processing
interpolated DFT
Hann window

Opis:

To improve the estimation of active power, the possibility of estimating the amplitude square of a signal component using the interpolation of the squared amplitude discrete Fourier transform (DFT) coefficients is presented. As with an energy-based approach, the amplitude square can be estimated with the squared amplitude DFT coefficients around the component peak and a suitable interpolation algorithm. The use of the Hann window, for which the frequency spectrum is well known, and the three largest local amplitude DFT coefficients gives lower systematic errors in squared interpolated approach or in better interpolated squared approach than the energy-based approach, although the frequency has to be estimated in the first step. All investigated algorithms have almost the same noise propagation and the standard deviations are about two times larger than the Cramér-Rao lower bound.

Źródło:

Metrology and Measurement Systems; 2011, 18, 4; 583-596
0860-8229

Pojawia się w:

Metrology and Measurement Systems

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 60.

Tytuł:

Numerical methods in understanding reaction pathways NOx oxidation

Autorzy:

Jaroszyńska-Wolińska, J.
Malinowski, S.

Powiązania:

https://bibliotekanauki.pl/articles/390595.pdf

Data publikacji:

2016

Wydawca:

Politechnika Lubelska. Wydawnictwo Politechniki Lubelskiej

Tematy:

NO
NO2
O3
DFT
CASSCF
CCSD
MP2

Opis:

Different quantum chemical models were applied in energetic analysis of the process of oxidation of NO and NO2 through reaction with ozone generated by non-thermal equilibrium (low temperature), atmospheric pressure plasma. The potential energy surfaces of systems comprising NO and NO2 with ozone were characterized. The NOx oxidation processes well known, at the molecular level, were modelled by ab initio quantum chemistry methods to calculate the total reaction energy, Et, of each step in the reaction chain. Quantum chemistry was further applied in an attempt to detect the presence of any transition states and to calculate the activation energy, Ea, of reactions (1) NO + O3 and (2) NO2 + O3 using the MP2 level of theory with three different basis sets and fine potential energy scan resolution.

Źródło:

Budownictwo i Architektura; 2016, 15, 3; 75-81
1899-0665

Pojawia się w:

Budownictwo i Architektura

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 61.

Tytuł:

Experimental and Theoretical Investigation to Study the Molecular Structure, Electronic Properties, UV–Vis Spectra of Coumarin 102

Autorzy:

Mohi, Ali T.
Abood, Tareq H.
Hadi, Hasan A.
Karim, Mahmood S.
Mutlik, Falah A-H.
Alwan, Tariq J.

Powiązania:

https://bibliotekanauki.pl/articles/1178533.pdf

Data publikacji:

2017

Wydawca:

Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN

Tematy:

DFT
Ionization potential
TDDFT
electron affinity
energy gap and UV spectra

Opis:

In this work, we study the structure, electronic properties and electronic spectra of Coumarin 102 (C102) dissolved in ethanol as an experimental-theoretical investigation. The various properties of the ground and excited electronic states of coumarins 102 using density functional theory (DFT) and time-dependent density functional theory (TDDFT) was calculated by the B3LYP density functional model with 6-31G(d,p) basis set by Gaussian 09 W program. Spectral characteristics of coumarin 102 have been probed into by methods of experimental UV-visible, and quantum chemistry. The UV spectrum was measured in Ethanol. The optimized structures, total energies, electronic states (HOMO- LUMO), energy gap, ionization potentials, electron affinities, chemical potential, global hardness, softness, global electrophilictity, dipole moment and electrostatic potential was calculated. were calculated. We find good agreement between experimental data of UV spectrum and TDDFT excitation energies.

Źródło:

World Scientific News; 2017, 70, 2; 216-229
2392-2192

Pojawia się w:

World Scientific News

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 62.

Tytuł:

Synthesis, Crystal Structure, and Properties of a Novel, Highly Sensitive Energetic, Coordination Compound: Iron (II) Carbohydrazide Perchlorate

Autorzy:

Liu, R.
Zhou, Z.
Qi, S.
Yang, L.
Wu, B.
Huang, H.
Zhang, T.

Powiązania:

https://bibliotekanauki.pl/articles/358343.pdf

Data publikacji:

2013

Wydawca:

Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego

Tematy:

iron (II) carbohydrazide perchlorate
energetic material
high
sensitivity
DFT
energy gap

Opis:

A single crystal of iron (II) carbohydrazide perchlorate [FeII (CHZ)3](ClO4)2 (FeCP), a novel, lead-free, energetic coordination compound, was synthesized and its structure determined by X-ray single crystal diffraction for the frst time. The crystal belongs to the monoclinic system P2(1)/n space group, with a = 1.0066(2) nm, b = 0.8458(2) nm, c = 2.1194(4) nm, β = 100.693(3)° and Z = 4. The central Fe(II) ion is coordinated to three bidentate carbohydrazide units through the carbonyl oxygen atom and an amino nitrogen atom, forming a six-coordinated, non-centrosymmetric complex cation. The thermal analyses by differential scanning calorimetry and thermogravimetry show that the onset temperature of thermal decomposition (152.7 °C) and the critical temperature of thermal explosion of FeCP (161.2 °C) are both much lower than those of other transition metal carbohydrazide perchlorate compounds, and also those of some other primary explosives in service. FeCP has a high enthalpy of combustion, as measured by oxygen bomb calorimetry. The impact, friction and fame sensitivity tests indicate that FeCP is extremely sensitive and hazardous. Unexpected explosions occurred even during the operational processes. In order to explore the intrinsic cause of these explosions, theoretical calculations of the orbital energies were performed based on DTF. These results reveal that the impact sensitivity is positively correlated with the energy gap between HOMO and LUMO: the smaller energy gap results in the higher impact sensitivity.

Źródło:

Central European Journal of Energetic Materials; 2013, 10, 1; 17-36
1733-7178

Pojawia się w:

Central European Journal of Energetic Materials

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 63.

Tytuł:

Mössbauer spectroscopy of reduced forms of a Fe-tetraphenylporphyrine complex

Autorzy:

Kaczmarzyk, T.
Rutkowska, I.
Dziliński, K.

Powiązania:

https://bibliotekanauki.pl/articles/148211.pdf

Data publikacji:

2015

Wydawca:

Instytut Chemii i Techniki Jądrowej

Tematy:

DFT calculations
electronic structure
iron-(tetraphenyl)porphyrin
Mössbauer spectroscopy
reduction process

Opis:

Molecular and electronic structure changes during successive reduction of a Fe-tetraphenylporphyrin chloride [Fe(III)(TPP):Cl] complex are reported on the basis of Mössbauer spectroscopy and DFT calculations. It is established that the attachment of additional electrons to a neutral Fe(III)(TPP):Cl molecule leads to signifi cant shortening of Fe-N distances at the fi rst stage of the reduction Fe(III)(TPP):Cl →Fe(II)(TPP) and lengthening of these bonds at the second stage Fe(II)(TPP)→Fe(I)(TPP). Changes of other bond lengths of the porphyrin ring also appear but in less degree. Interaction of Fe(II) and Fe(I)(TPP) with tetrahydrofuran (THF) solvent is considered. Electron configuration of Fe(II)(TPP) corresponds to intermediate-spin (S = 1) state and in the case of Fe(I)(TPP) low-spin state (S = ½) is observed. Electron density distribution in Fe(II)- and Fe(I)(TPP) complexes, in association with Mössbauer data, is analyzed. Good correlation between experimental and theoretical results was obtained.

Źródło:

Nukleonika; 2015, 60, 1; 51-55
0029-5922
1508-5791

Pojawia się w:

Nukleonika

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 64.

Tytuł:

Galvanic contacting effect of pyrite on xanthate adsorption on galena surface: DFT simulation and cyclic voltammetric measurements

Autorzy:

Ke, B.
Chen, J.
Li, Y.
Chen, Y.

Powiązania:

https://bibliotekanauki.pl/articles/110904.pdf

Data publikacji:

2018

Wydawca:

Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej

Tematy:

adsorption
DFT
galvanic interaction
pyrite surface
galena surface
cyclic voltammetric measurements

Opis:

The effect of galvanic interaction between pyrite and galena on xanthate adsorbing on the galena surface has been investigated by means of density functional theory (DFT) and cyclic voltammetric measurements. The calculated results show that differences in the contact site and contact distance between galena and pyrite can affect the intensity of the galvanic interaction, and the relationship between the intensity of galvanic interaction and the adsorption ability of xanthate on galena surface has been studied in detail. In general, the galvanic interaction between pyrite and galena surface can enhance the adsorption of xanthate on the galena surface. The adsorption energies of xanthate on the galena surface decrease with the decrease of contact distance, and when the contact distance is lower than 4 Å, the adsorption energies decrease significantly at Pb-Pb, Pb-S and S-S sites. In particular, at the contact distance of 3 Å, a sharp decrease of adsorption energy is observed at the Pb-Pb contact site; in this case, the negative shift of the Pb-S bonding range and DOS non-locality at Pb-Pb contact site are significantly greater than that of the S-S or Pb-S contact sites. The cyclic voltammetric measurements reveal that the galvanic interaction between galena and pyrite improves the adsorption of xanthate on galena surface, which is in good agreement with the DFT results.

Źródło:

Physicochemical Problems of Mineral Processing; 2018, 54, 3; 826-836
1643-1049
2084-4735

Pojawia się w:

Physicochemical Problems of Mineral Processing

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 65.

Tytuł:

Continuous and discontinuous linear approximation of the window spectrum by least squares method

Autorzy:

Borkowski, J.

Powiązania:

https://bibliotekanauki.pl/articles/221777.pdf

Data publikacji:

2011

Wydawca:

Polska Akademia Nauk. Czytelnia Czasopism PAN

Tematy:

data window
spectrum approximation
interpolated DFT
LIDFT
spectrum estimation
zero padding

Opis:

This paper presents the general solution of the least-squares approximation of the frequency characteristic of the data window by linear functions combined with zero padding technique. The approximation characteristic can be discontinuous or continuous, what depends on the value of one approximation parameter. The approximation solution has an analytical form and therefore the results have universal character. The paper presents derived formulas, analysis of approximation accuracy, the exemplary characteristics and conclusions, which confirm high accuracy of the approximation. The presented solution is applicable to estimating methods, like the LIDFT method, visualizations, etc.

Źródło:

Metrology and Measurement Systems; 2011, 18, 3; 379-390
0860-8229

Pojawia się w:

Metrology and Measurement Systems

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 66.

Tytuł:

Protein thermal stabilization in aqueous solutions of osmolytes

Autorzy:

Bruździak, Piotr
Panuszko, Aneta
Jourdan, Muriel
Stangret, Janusz

Powiązania:

https://bibliotekanauki.pl/articles/1038842.pdf

Data publikacji:

2016

Wydawca:

Polskie Towarzystwo Biochemiczne

Tematy:

water structure
protein stability
circular dichroism
FT-IR spectroscopy
DFT calculations

Opis:

Proteins' thermal stabilization is a significant problem in various biomedical, biotechnological, and technological applications. We investigated thermal stability of hen egg white lysozyme in aqueous solutions of the following stabilizing osmolytes: Glycine (GLY), N-methylglycine (NMG), N,N-dimethylglycine (DMG), N,N,N-trimethylglycine (TMG), and trimethyl-N-oxide (TMAO). Results of CD-UV spectroscopic investigation were compared with FTIR hydration studies' results. Selected osmolytes increased lysozyme's thermal stability in the following order: Gly>NMG>TMAO≈DMG>TMG. Theoretical calculations (DFT) showed clearly that osmolytes' amino group protons and water molecules interacting with them played a distinctive role in protein thermal stabilization. The results brought us a step closer to the exact mechanism of protein stabilization by osmolytes.

Źródło:

Acta Biochimica Polonica; 2016, 63, 1; 65-70
0001-527X

Pojawia się w:

Acta Biochimica Polonica

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 67.

Tytuł:

Computational characterization of (E)-N-(3-bromo-4-fluorobenzylidene)-4-nitrobenzenamine compound

Autorzy:

Premalatha, R.
Santhi, N.

Powiązania:

https://bibliotekanauki.pl/articles/1179594.pdf

Data publikacji:

2017

Wydawca:

Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN

Tematy:

DFT
HOMO-LUMO and NBO
IR and Raman spectra
Schiff base

Opis:

Schiff bases are aldehyde- or ketone-like compounds in which the carbonyl group is replaced by an imine or azomethine group. In this work, (E)-N-(3-bromo-4-fluorobenzylidene)-4-nitrobenzenamine have been synthesized and characterized by IR, 1H and 13C NMR spectral studies. Density functional theory (DFT) has been used to optimize geometrical parameters, atomic charges, vibrational wavenumbers and intensity of vibrational bands. The molecular properties HOMO-LUMO, NBO were calculated using B3LYP/6-311G (d, p) basis set. The polarizability and first order hyperpolariza-bility of the title Compound was calculated and interpreted.

Źródło:

World Scientific News; 2017, 74; 121-140
2392-2192

Pojawia się w:

World Scientific News

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 68.

Tytuł:

Electronic, optical and non-linear optical properties of an N-cyclohexylacrylamide molecule : a potential optoelectronic agent

Autorzy:

Tanış, E.
Çankaya, N.

Powiązania:

https://bibliotekanauki.pl/articles/1818235.pdf

Data publikacji:

2020

Wydawca:

Polska Akademia Nauk. Stowarzyszenie Elektryków Polskich

Tematy:

N-cyclohexylacrylamide
electronic properties
optical properties
non-linear optical properties
DFT

Opis:

In this article, synthesis, electronic and optical properties of an N-cyclohexyl-acrylamide (NCA) molecule are described based on different solvent environments and supported by theoretical calculations. Theoretical calculations have been carried out using a density function theory (DFT). Temperature dependence of the sample electrical resistance has been obtained by a four-point probe technique. Experimental and semitheoretical parameters such as optical density, transmittance, optical band gap, refractive index of the NCA for different solvents were obtained. Both optical values and electrical resistance values have shown that NCA is a semiconductor material. The values of HOMO and LUMO energy levels of the headline molecule indicate that it can be used as the electron transfer material in OLEDs. All results obtained confirm that the NCA is a candidate molecule for OLED and optoelectronic applications.

Źródło:

Opto-Electronics Review; 2020, 28, 4; 191--196
1230-3402

Pojawia się w:

Opto-Electronics Review

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 69.

Tytuł:

Synthesis, computational, anticancerous and antiproliferative effects of some copper, manganese and zinc complexes with ligands derived from symmetrical 2,2’-diamino-4,4’-dimethyl-1,1’-biphenyl-salicylaldehyde

Autorzy:

Ababneh, Taher S.
El-Khateeb, Mohammad
Tanash, Aissar K.
AL-Shboul, Tareq M.A.
Shammout, Mohammad Jamal A.
Jazzazi, Taghreed M.A.
Alomari, Mohammad
Daoud, Safa
Talib, Wamidh H.

Powiązania:

https://bibliotekanauki.pl/articles/1849324.pdf

Data publikacji:

2021

Wydawca:

Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie

Tematy:

tetradentate schiff base
symmetrical metal complexes
DFT calculation
spectroscopy
anticancerous
antiproliferative

Opis:

Four new symmetrical Schiff bases derived from 2,2’-diamino-4,4’-dimethyl-1,1’-biphenyl-salicylaldehyde have been synthesized and characterized by elemental analysis and different spectroscopic techniques. The reaction of 2,2’-diamino-4,4’-dimethyl-1,1’-biphenyl with two equivalents of 5-tert-butyl-, 3,5-dinitro-, 3,5-dibromo- and 3-tert-butyl-salicylaldehyde yielded 2,2’-bis(5-tert-butyl-salicylideneamino)-4,4’-dimethyl-1,1’-biphenyl (A1) as well as the 3,5-dinitro- (A2), 3,5-dibromo- (A3) and 3-tert-butyl- (A4) substituted derivatives. The tetradentate ligands were then reacted with copper-, manganese- and zinc-acetate producing the tetra-coordinate metal complexes which were characterized by FTIR, UV-Visible spectroscopy, magnetic susceptibility and elemental analysis. Zinc complexes were characterized by 1H-NMR spectroscopy. Density functional theory (DFT) calculations at the B3LYP/6-31G(d) level of theory were carried out to fully optimize and examine the molecular geometries of complexes. Subsequently, IR vibrational and UV-Vis absorption spectra were computed and correlated with the observed values and the results are in good agreement with the experimental data. The anticancerous and antiproliferative activity of the A3 ligand and its metal complexes were determined.

Źródło:

Polish Journal of Chemical Technology; 2021, 23, 1; 7-15
1509-8117
1899-4741

Pojawia się w:

Polish Journal of Chemical Technology

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 70.

Tytuł:

The Mechanism of Redox Reaction between Palladium(II) Complex Ions and Potassium Formate in Acidic Aqueous Solution

Autorzy:

Wojnicki, M.
Podborska, A.

Powiązania:

https://bibliotekanauki.pl/articles/356614.pdf

Data publikacji:

2017

Wydawca:

Polska Akademia Nauk. Czytelnia Czasopism PAN

Tematy:

analysis
spectrophotometry
palladium
chloride
speciation
TD-DFT
recycling
recovery
kinetics
formate

Opis:

The kinetics studies of redox reaction between palladium(II) chloride complex ions and potassium formate in acidic aqueous solutions was investigated. It was shown, that the reduction reaction of Pd(II) is selective in respect to Pd(II) complex structure. The kinetic of the process was monitored spectrophotometrically. The influence of chloride ions concentration, Pd(II) initial concentration, reductant concentration, ionic strength as well as the temperature were investigated in respect to the process dynamics. Arrhenius equation parameters were determined and are equal to 65.8 kJ/mol, and A = 1.12×10¹¹ s^-1.

Źródło:

Archives of Metallurgy and Materials; 2017, 62, 2A; 737-745
1733-3490

Pojawia się w:

Archives of Metallurgy and Materials

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 71.

Tytuł:

FT-IR, FT-Raman, NMR and U-V Spectral investigation: Computation of vibrational frequency, chemical shifts and electronic structure calculations of 1-bromo-4-nitrobenzene

Autorzy:

Shakila, G.
Saleem, H.
Sundaraganesan, N.

Powiązania:

https://bibliotekanauki.pl/articles/1178760.pdf

Data publikacji:

2017

Wydawca:

Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN

Tematy:

DFT
FT-IR
FT-Raman
HOMO-LUMO and MEP
NMR
UV analysis

Opis:

The FT-IR and FT-Raman spectra of 1-bromo-4-nitrobenzene (1B4NB) have been recorded in the range 400-4000 cm-1 and 100-4000 cm-1 respectively. Also the NMR and UV-VIS spectra of 1B4NB have been recorded and analyzed. The molecular structures, fundamental vibrational frequencies and intensity of the vibrational bands are investigated and interpreted theoretically with the use of structure optimizations and normal coordinate force field calculations based on density functional theory (DFT) with basis sets 6-31+G(d,p) and 6-311++G(d,p). The vibrational wave number assignments were made from potential energy distribution (PED) calculations using Veda program. The simulated vibrational spectra of the molecule show excellent agreement with the experimental spectra. The hyper conjugative interaction energy (E)2 and electron densities of donor (i) and acceptor (j) bonds were calculated using NBO analysis. The energy gap of the molecule was found using HOMO and LUMO calculation. The electronic transition was studied using UV-Visible analysis of the title molecule with B3LYP/6-311++G (d,p) level of basis set. The microscopic Non-linear optical behavior, the molecular electrostatic potential (MEP), chemical descriptors and thermo dynamical properties of the title compound were also calculated. In addition, the 1H and 13C NMR chemical shifts values of 1B4NB in the ground state for B3LYP/ 6-311++G (d,p) basis set were also calculated using Gauge independent atomic orbital (GIAO) method.

Źródło:

World Scientific News; 2017, 61, 2; 150-185
2392-2192

Pojawia się w:

World Scientific News

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 72.

Tytuł:

Modeling computational studies of modified drug molecules binding to the LRRK2 protein in the treatment of Parkinson’s disease

Autorzy:

Shah, H.
Darsey, J. A.

Powiązania:

https://bibliotekanauki.pl/articles/284742.pdf

Data publikacji:

2018

Wydawca:

Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Polskie Towarzystwo Biominerałów

Tematy:

LRRK2 proteins
Parkinson
Computational Modeling
IC50
Density Functional Theory
DFT

Opis:

Parkinson’s disease is a neurodegenerative and progressive disease of the central nervous system. It affects more than 10 million patients worldwide and the symptoms allow for little to no control for movement. These symptoms appear because the chemical messenger dopamine is being made in small quantities from impaired cells. However, the disease often forms when there is a mutation in the LRRK2 gene, as the functions of the protein become abnormal. The IC50 value is essential information about molecules because it measures their effectiveness. The goal of this research was to design molecules with a lower IC50 value. This was first done by modeling molecules on the molecular modeling program, Gaussian 09. Modifications were made to molecules that were said to bind to the LRRK2 protein. Modifications ranged from adding a single atom or replacing atoms with groups. After running these molecules on the program, the total energy was found. Using the equation found from the correlation between 1/IC50 and the total energy, the IC50 value was predicted for each of the modified molecules. Many of the modified molecules portrayed a positive percent difference between the original IC50 value and the new one. This saves both time and money because the molecules with lower IC50 values can be made, preserving the resources. After creating the molecule with a low IC50 value, further experimental procedures can be taken; this is a large step in assisting researchers to reach a potential treatment because it is more efficient.

Źródło:

Engineering of Biomaterials; 2018, 21, 145; 2-7
1429-7248

Pojawia się w:

Engineering of Biomaterials

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 73.

Tytuł:

Electronic structure, stability, and strength of Cu–NiAl alloys : experiment and DFT investigation

Autorzy:

Zarhri, Zakaryaa

Powiązania:

https://bibliotekanauki.pl/articles/2074202.pdf

Data publikacji:

2022

Wydawca:

Polska Akademia Nauk. Stowarzyszenie Elektryków Polskich

Tematy:

mechanical properties
electronic structure
DFT study
Cu-doped nickel aluminide
formation energy

Opis:

In this study, the copper doping effect on the NiAl structural stability, strength, and electronic structure was investigated. The samples were prepared using induction melting at 2073 K. This material presents good mechanical and physical properties such as high-temperature strength, fatigue or impact, and corrosion resistance which meet technical requirements of many applications. The microstructure of the Cu-doped nickel aluminide was studied using a metallurgical microscope and its lattice parameter was also studied and characterized using an X-ray diffractometer for different concentrations of Cu. The lattice constant of the existing phases was calculated, and it was found that the lattice distortion and gamma prime phase energy have high values allowing the increase of the entropy term of the alloy and subsequently increasing its hardness. From the ab-initio calculation, it was determined that the Cu atoms have the Al sites as a preferred site and prefer to bond with Ni atoms which leads to the improvement of the material hardness. Ab-initio density functional theory was applied to study the formation energy that revealed increasing with Cu amount.

Źródło:

Opto-Electronics Review; 2022, 30, 2; art. no. e141707
1230-3402

Pojawia się w:

Opto-Electronics Review

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 74.

Tytuł:

Wybrane problemy wyznaczania widma amplitudowego sygnału okresowego
Selected aspects of determining the amplitude spectrum of a periodic signal

Autorzy:

Purczyński, J.

Powiązania:

https://bibliotekanauki.pl/articles/377066.pdf

Data publikacji:

2012

Wydawca:

Politechnika Poznańska. Wydawnictwo Politechniki Poznańskiej

Tematy:

sygnał okresowy
widmo amplitudowe sygnału okresowego
amplituda sygnału okresowego
DFT
okno Dirichleta

Opis:

W pracy rozpatrzono błąd wartości amplitudy sygnału okresowego wyznaczonej za pomocą DFT wywołany próbkowaniem niekoherentnym oraz nieznanym przesunięciem fazowym w chwili próbkowania. Błąd ten jest dwuwymiarową zmienną losową zależną od współczynnika desynchronizacji aԑ (- 0.5,0.5)oraz przesunięcia t₀ԑ(0,T)gdzie T-okres sygnału. Przeprowadzono symulacje komputerowe (4 min. powtórzeń) wykonując uśrednianie względem poszczególnych zmiennych losowych i wyznaczając rozkłady brzegowe. Ponadto, porównano błąd amplitudy wynikający z zastosowania klasycznego okna Dirichleta z błędem zastosowania symetrycznego okna Dirichleta [2], W tym ostatnim przypadku wyznaczono postać analityczną błędu.
The paper examines the error - of periodic signal amplitude value determined using DFT - induced both by incoherent sampling and unknown phase shift at the moment of sampling. The error is a two-dimensional random variable dependent on the desynchronization coefficient aԑ (- 0.5,0.5) and the shift t₀ԑ(0,T) where T- period of the signal. Computer simulations were conducted (4 m. iterations) performing averaging in relation to particular random variables and determining marginal distributions. Furthermore, the comparison was made between the amplitude error resulting from application of a classical Dirichlet window and the error of applying a symmetric Dirichlet window [2], In the latter case the analytic form of the error was determined.

Źródło:

Poznan University of Technology Academic Journals. Electrical Engineering; 2012, 69; 33-40
1897-0737

Pojawia się w:

Poznan University of Technology Academic Journals. Electrical Engineering

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 75.

Tytuł:

Electrical and thermal properties of anthraquinone layers
Własności elektryczne i termiczne warstw antrachinonu

Autorzy:

Kania, Sylwester
Kuliński, Janusz
Sikorski, Dominik

Powiązania:

https://bibliotekanauki.pl/articles/952827.pdf

Data publikacji:

2019

Wydawca:

Politechnika Łódzka. Wydawnictwo Politechniki Łódzkiej

Tematy:

anthraquinone
differential scanning calorimetry
DSC
DFT
calculations
antrachinon
różnicowa kalorymetria skaningowa
obliczenia

Opis:

Quantum-chemical calculations indicate that the bond lengths in the anthraquinone anthracene backbone are shorter than the corresponding bonds in unsubstituted anthracene. The shape of the frontier molecular orbitals (FMO) indicates the possibility of more efficient electron capture by the anthraquinone molecule than by the anthracene molecule while maintaining stability in the conditions prevailing in electrochemical cells. Differential scanning calorimetry (DSC) studies indicate the temperature stability of anthraquinone above the melting point up to 300°C. The glass transition is determined at about 100°C.
Obliczenia kwantowo-chemiczne wskazują, że długości wiązań w szkielecie antracenowym antrachinonu w zewnętrznym pierścieniu benzenowym są krótsze niż odpowiadające im wiązania w niepodstawionym antracenie. Świadczy to o zwiększeniu energii rezonansu w zewnętrznych pierścieniach benzenowych cząsteczki antrachinonu. Kształt orbitali zewnętrznych (FMO) wskazuje na możliwość bardziej efektywnego przejmowania elektronów przez cząsteczkę antrachinonu niż przez cząsteczkę antracenu z zachowaniem stabilności w warunkach panujących w komórkach elektrochemicznych. Badania DSC wskazują na stabilność chemiczną antrachinonu powyżej temperatury topnienia aż do 300°C. Antrachinon w pobliżu temperatury 100°C wykazuje przemianę zeszklenia, poniżej tej temperatury nie wykazuje przemian fazowych. Własności elektryczne i termiczne antrachinonu wskazują na duży potencjał tego związku dla zastosowań w elektronice organicznej.

Źródło:

Scientific Bulletin. Physics / Technical University of Łódź; 2019, 40; 13-25
1505-1013
2449-982X

Pojawia się w:

Scientific Bulletin. Physics / Technical University of Łódź

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 76.

Tytuł:

The Ru Impurity Effect on Electronic, Optical and Thermoelectric Properties of MoS2 Nano-Sheet: a DFT Study

Autorzy:

Dezfuli, Firouzeh Motamad
Boochani, Arash
Parhizgar, Sara Sadat
Darabi, Elham

Powiązania:

https://bibliotekanauki.pl/articles/2049711.pdf

Data publikacji:

2021

Wydawca:

Polska Akademia Nauk. Czytelnia Czasopism PAN

Tematy:

MoS2Ru nano-sheet
DFT
electronic properties
optical properties
thermoelectric properties

Opis:

The electronic, optical and thermoelectric properties of MoS2 nano-sheet in presence of the ru impurity have been calculated by density functional theory framework with generalized gradient approximation. The MoRuS2 nano-sheet electronic structure was changed to the n-type semiconductor by 1.3 eV energy gap. The optical coefficients were shown that the loosing optical energy occurred in the higher ultraviolet region, so this compound is a promising candidate for optical sensing in the infrared and visible range. The thermoelectric behaviors were implied to the good merit parameter in the 100K range and room temperatures and also has high amount of power factor in 600K which made it for power generators applications.

Źródło:

Archives of Metallurgy and Materials; 2021, 66, 2; 461-468
1733-3490

Pojawia się w:

Archives of Metallurgy and Materials

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 77.

Tytuł:

Frequency and Damping Estimation Methods - An Overview

Autorzy:

Zieliński, T. P.
Duda, K.

Powiązania:

https://bibliotekanauki.pl/articles/220581.pdf

Data publikacji:

2011

Wydawca:

Polska Akademia Nauk. Czytelnia Czasopism PAN

Tematy:

damped sinusoids
frequency estimation
damping estimation
linear prediction
subspace methods
interpolated DFT

Opis:

This overview paper presents and compares different methods traditionally used for estimating damped sinusoid parameters. Firstly, direct nonlinear least squares fitting the signal model in the time and frequency domains are described. Next, possible applications of the Hilbert transform for signal demodulation are presented. Then, a wide range of autoregressive modelling methods, valid for damped sinusoids, are discussed, in which frequency and damping are estimated from calculated signal linear self-prediction coefficients. These methods aim at solving, directly or using least squares, a matrix linear equation in which signal or its autocorrelation function samples are used. The Prony, Steiglitz-McBride, Kumaresan-Tufts, Total Least Squares, Matrix Pencil, Yule-Walker and Pisarenko methods are taken into account. Finally, the interpolated discrete Fourier transform is presented with examples of Bertocco, Yoshida, and Agrež algorithms. The Matlab codes of all the discussed methods are given. The second part of the paper presents simulation results, compared with the Cramér-Rao lower bound and commented. All tested methods are compared with respect to their accuracy (systematic errors), noise robustness, required signal length, and computational complexity.

Źródło:

Metrology and Measurement Systems; 2011, 18, 4; 505-528
0860-8229

Pojawia się w:

Metrology and Measurement Systems

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 78.

Tytuł:

Critical Assessment Of The Issues In The Application Of Hilbert Transform To Compute The Logarithmic Decrement
Krytyczna analiza zastosowań transformaty Hilberta do obliczeń logarytmicznego dekrementu tłumienia

Autorzy:

Majewski, M.
Magalas, L. B.

Powiązania:

https://bibliotekanauki.pl/articles/353996.pdf

Data publikacji:

2015

Wydawca:

Polska Akademia Nauk. Czytelnia Czasopism PAN

Tematy:

logarithmic decrement
internal friction
mechanical spectroscopy
Hilbert transform
envelope
interpolated discrete Fourier transform DFT
dekrementacja logarytmiczna
tarcie wewnętrzne
spektroskopia mechaniczna
transformacja Hilberta
obwiednia
interpolowana dyskretna transformata Fouriera DFT

Opis:

The parametric OMI (Optimization in Multiple Intervals), the Yoshida-Magalas (YM) and a novel Hilbert-twin (H-twin) methods are advocated for computing the logarithmic decrement in the field of internal friction and mechanical spectroscopy of solids. It is shown that dispersion in experimental points results mainly from the selection of the computing methods, the number of oscillations, and noise. It is demonstrated that conventional Hilbert transform method suffers from high dispersion in internal friction values. It is unequivocally demonstrated that the Hilbert-twin method, which yields a ‘true envelope’ for exponentially damped harmonic oscillations is superior to conventional Hilbert transform method. The ‘true envelope’ of free decaying strain signals calculated from the Hilbert-twin method yields excellent estimation of the logarithmic decrement in metals, alloys, and solids.
Do estymacji logarytmicznego dekrementu tłumienia w spektroskopii mechanicznej i w badaniach tarcia wewnętrznego ciał stałych zarekomendowano w pracy następujące metody obliczeniowe: metodę parametryczną OMI (Optimization in Multiple Intervals), metodę Yoshida-Magalas (YM) i nową metodę Hilbert-twin (H-twin). Wykazano, że dyspersja punktów eksperymentalnych logarytmicznego dekrementu tłumienia i tarcia wewnętrznego zdeterminowana jest przede wszystkim wyborem metody obliczeniowej, liczbą oscylacji i obecnością szumu w dyskretnych sygnałach odkształceń sprężystych badanych materiałów. Zastosowanie do obliczeń logarytmicznego dekrementu tłumienia klasycznej transformaty Hilberta powoduje bardzo dużą dyspersję punktów eksperymentalnych. W pracy wykazano, że metoda Hilbert-twin (transformata Hilberta zbliźniakowanego dyskretnego sygnału odkształceń sprężystych) po raz pierwszy umożliwia uzyskanie „prawdziwej obwiedni” wykładniczo tłumionych drgań harmonicznych próbki. Nowa metoda obliczeń „prawdziwej obwiedni” umożliwia bardzo dokładną estymację logarytmicznego dekrementu tłumienia w materiałach metalicznych i w ciałach stałych.

Źródło:

Archives of Metallurgy and Materials; 2015, 60, 2A; 1105-1108
1733-3490

Pojawia się w:

Archives of Metallurgy and Materials

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 79.

Tytuł:

5',8-Cyclo-2'-deoxyadenosine (cdA) formation by γ-radiation. Theoretical quantum mechanics study

Autorzy:

Karwowski, Boleslaw
Grand, Andre
Cadet, Jean

Powiązania:

https://bibliotekanauki.pl/articles/1040482.pdf

Data publikacji:

2009

Wydawca:

Polskie Towarzystwo Biochemiczne

Tematy:

5',8-cyclo-2'-deoxyadenosine
DNA damage
ionizing radiation
density functional theory (DFT)

Opis:

Reactions of reactive oxygen species and more specifically - of hydroxyl radical (•OH) - with nucleosides may lead to the generation of radicals in the base and 2-deoxyribose moieties. In the present study emphasis was put on the possible reaction modes of 2'-deoxyadenosine (dA) radicals, leading to the formation of related 5',8-cyclonucleosides. It appears that the prerequisite for the formation of 5',8-cyclo-2'-deoxyadenosine (cdA) is the adoption of O4'-exo conformation by 2-deoxyribose; however, this is the least energetically favored conformer among the different puckered forms adopted by the furanose ring. The O4'-exo conformation was found to be present in each of the discussed mechanisms.

Źródło:

Acta Biochimica Polonica; 2009, 56, 4; 655-662
0001-527X

Pojawia się w:

Acta Biochimica Polonica

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 80.

Tytuł:

Comparison of sine-wave frequency estimation methods in respect of speed and accuracy for a few observed cycles distorted by noise and harmonics

Autorzy:

Borkowski, J.
Kania, D.
Mroczka, J.

Powiązania:

https://bibliotekanauki.pl/articles/220583.pdf

Data publikacji:

2018

Wydawca:

Polska Akademia Nauk. Czytelnia Czasopism PAN

Tematy:

DFT spectrum interpolation
short-time frequency estimation
statistical analysis
Prony LS
TLS
ESPRIT

Opis:

The paper deals with frequency estimation methods of sine-wave signals for a few signal cycles and consists of two parts. The first part contains a short overview where analytical error formulae for a signal distorted by noise and harmonics are presented. These formulae are compared with other accurate equations presented previously by the authors which are even more accurate below one cycle in the measurement window. The second part contains a comparison of eight estimation methods (ESPRIT, TLS, Prony LS, a newly developed IpDFT method and four other 3-point IpDFT methods) in respect of calculation time and accuracy for an ideal sine-wave signal, signal distorted by AWGN noise and a signal distorted by harmonics. The number of signal cycles is limited from 0.1 to 3 or 5. The results enable to select the most accurate/fastest estimation method in various measurement conditions. Parametric methods are more accurate but also much slower than IpDFT methods (up to 3000 times for the number of samples equal to 5000). The presented method is more accurate than other IpDFT methods and much faster than parametric methods, which makes it possible to use it as an alternative, especially in real-time applications.

Źródło:

Metrology and Measurement Systems; 2018, 25, 2; 283-302
0860-8229

Pojawia się w:

Metrology and Measurement Systems

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 81.

Tytuł:

Równowagi asocjacyjne alkilopochodnych mocznika i tiomocznika
Association equilibria of alkyl derivatives of urea and thiourea

Autorzy:

Rospenk, M.
Koll, A.
Obrzud, M.

Powiązania:

https://bibliotekanauki.pl/articles/172815.pdf

Data publikacji:

2017

Wydawca:

Polskie Towarzystwo Chemiczne

Tematy:

model samoasocjacji
momenty dipolowe
średnia masa cząsteczkowa
obliczenia DFT
pochodne mocznika i tiomocznika
model of self-association
dipole moments
average molecular weight
FTIR spectra
DFT calculation
derivatives of urea and thiourea

Opis:

The studies and comparison of a series of molecular mono- and di-substituted derivatives of urea and thiourea in solvents of increasing polarity are presented [1–4]. These substances are characterized by a high tendency to self-associate through the formation of intermolecular hydrogen bonds due to the presence in their structure both groups as donors (NH) as well as proton acceptors (C=O) or (C=S). Studies were performed by using IR spectroscopy, method of measuring the average molecular weight and the dipole moments. The experimental data were verified by DFT quantum chemical calculations with B3PW91 correlation functional. Simultaneous use of these techniques alowed establishing not only the efficiency of aggregation, but also the structure and polarity of formed aggregates. It was shown, that in solvents with weak acidic C-H groups the aggregation was strongly limited because of molecular interactions between solute and solvent. The theoretical DFT calculations which included the impact of the environment on the nature of interactions in the complex were carried out [e.g. Scheme 4.1.4]. A combination of geometry optimization in polarizable continuum model (PCM) with the connection of chloroform molecules (1,2-dichloroethane) with urea dimers enabled to obtain the expected theoretical simulation compliance with the experiment. The equilibrium constants were calculated on the basis of data obtained in two independent methods of measurement: IR spectroscopy and measurements of average molecular weights. Good agreement of experimental data of both research techniques were found up to concentration of 0.03 mol/dm3 [Fig. 2.5]. The type of associates have been assessed following the dipole moments measured as a function of concentration, and on the results of density-functional theory (DFT) calculations on the structure and energy of particular species. All of the urea derivatives demonstrated an increase in dipole moment with increased concentration, suggesting linear-type aggregation [Fig. 4.1.3]. Contrastingly, the dipole moments of the N,N-dimethylthiourea and mono-N-alkyl-substituted thioureas decreased with concentration and suggest that cyclic dimers or trimers are formed by C=S…(HR)₂N-C=S interactions [Fig. 4.2.2]. The efficiency of self-aggregation was described by use of two equilibrium constants. The first constant, K₁, was describing dimer formation and the second constant, K₂, the subsequent multimer formation. In N,N’-thioureas aggregation was lower than for the related urea compounds [Table 4.1.1 and Table 4.2.1]. Differences between urea and thiourea derivatives result from the fact that the ureas are stronger bases and, therefore, more active in aggregation.

Źródło:

Wiadomości Chemiczne; 2017, 71, 7-8; 559-608
0043-5104
2300-0295

Pojawia się w:

Wiadomości Chemiczne

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 82.

Tytuł:

EPR study on sugar radicals utilized for detection of radiation treatment of food

Autorzy:

Guzik, G. P.
Stachowicz, W.
Michalik, J.

Powiązania:

https://bibliotekanauki.pl/articles/146706.pdf

Data publikacji:

2012

Wydawca:

Instytut Chemii i Techniki Jądrowej

Tematy:

density functional theory (DFT)
dried fruits
electron paramagnetic resonance (EPR)
irradiation
mannose
sorbose

Opis:

Radicals produced by ionizing radiation in sugars, the components of dried and raw fruits give rise to stable multicomponent electron paramagnetic resonance (EPR) signals unidentified so far. The subject of the present EPR study is to identify the radicals stabilized in gamma-irradiated crystalline sugars, D(+)mannose and L(-)sorbose extracted from cranberries (Vaccininum oxycoccos) and rowan berries (Sorbus aucuparia), respectively. EPR measurements and density functional theory (DFT) simulations were employed for that purpose.

Źródło:

Nukleonika; 2012, 57, 4; 545-549
0029-5922
1508-5791

Pojawia się w:

Nukleonika

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 83.

Tytuł:

Local structure and cohesive properties of mixed thorium and uranium dioxides calculated by "ab initio" method

Autorzy:

Dąbrowski, L.
Szuta, M.

Powiązania:

https://bibliotekanauki.pl/articles/147874.pdf

Data publikacji:

2012

Wydawca:

Instytut Chemii i Techniki Jądrowej

Tematy:

uranium
thorium dioxide
DFT+U
LDA
GGA
local structure
cohesive properties
bulk modulus

Opis:

Density functional theory (DFT) results of calculations of the mixed thorium and uranium dioxide Th1-xUxO2 for the following mole ratio x = 0, 0.25, 0.75 and 1 are presented and discussed. "Ab initio" calculations were performed using the Wien2k program package. To compute the unit cell parameters the 12 atom super-cell were chosen. The lattice parameters were calculated through minimization of the total energy by the change of lattice parameters and atom displacement within the unit cell. Calculations were performed for five different exchange energy approximations EXC with and without corrective orbital potential U, and obtained lattice constants are presented graphically and compared with experimental data. It is established that the initially assumed oxygen location within the unit cell plus or minus 0.25 of the mixed compounds are not their equilibrium positions. The oxygen atoms within the unit cell undergo dislocation in the (111) direction. So, the distances oxygen-uranium are smaller than the distances oxygen-thorium. The change of local structure is presented graphically and appropriate parameters values are given in Table. The bulk modulus and the cohesive properties are also counted and shown graphically.

Źródło:

Nukleonika; 2012, 57, 1; 101-107
0029-5922
1508-5791

Pojawia się w:

Nukleonika

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 84.

Tytuł:

Zastosowanie okien o płaskiej charakterystyce widmowej do bezpośredniego obliczania fazora w sieciach elektroenergetycznych
Application of flat-top windows for direct phasor estimation in electric power systems

Autorzy:

Duda, K.
Barczentewicz, S.
Bień, A.

Powiązania:

https://bibliotekanauki.pl/articles/268556.pdf

Data publikacji:

2015

Wydawca:

Politechnika Gdańska. Wydział Elektrotechniki i Automatyki

Tematy:

fazor
okno czasowe
dyskretne przekształcenie Fouriera
DFT
phasor
time window
discrete Fourier transform

Opis:

W artykule przedstawiono wyniki zastosowania okna czasowego o płaskiej charakterystyce amplitudowej do obliczania fazora w sieciach elektroenergetycznych. Otrzymane wyniki porównano do wyników uzyskanych dla okna prostokątnego i okna Hanna. Do określenia właściwości porównywanych metod obliczeniowych wykorzystano niektóre z testów zgodności standardu IEEE Standard for Synchrophasor Measurements for Power Systems, oraz zdefiniowane tam błędy TVE (total vector error) i FE (frequency error). Otrzymane wyniki wskazują, że okna o płaskiej charakterystyce widmowej pozwalają istotnie poprawić dokładność estymacji fazora zwłaszcza w stanie ustalonym.
This paper presents results of direct phasor estimation by DFT with application of flat-top windows. Results obtained with rectangular window and Hann window are also presented for comparison. The quality of the phasor estimation is evaluated by TVE (total vector error) and FE (frequency error) as defined in the IEEE Standard for Synchrophasor Measurements for Power Systems. The application of flat-top windows resulted in significant reduction of TVE in steadystate compliance tests. For actual frequency fin=50±2,5 Hz maximum TVE was reduced about 30 times as compare to Hann window. The smallest maximum FE errors were also obtained for flat-top window. In dynamic compliance tests flat-top windows performed only slightly better than Hann window and rectangular window in frequency estimation, and maximum TVE error is even slightly higher than for rectangular window for modulating frequency above 2,5 Hz. Straightforward computation of the phasor based on one DFT bin has computational complexity N. Application of FFT algorithms is not advised, because only one DFT bin is required. The phasor may be computed on sample by sample basis by discrete time convolution with FIR filter. In that case reporting frequency is the same as the sampling frequency of the signal.

Źródło:

Zeszyty Naukowe Wydziału Elektrotechniki i Automatyki Politechniki Gdańskiej; 2015, 47; 43-46
1425-5766
2353-1290

Pojawia się w:

Zeszyty Naukowe Wydziału Elektrotechniki i Automatyki Politechniki Gdańskiej

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 85.

Tytuł:

Association of model peptides and dehydropeptides: N-acetyl-l-butyrine and (Z)-dehydrobutyrine N',N'-dimethylamides

Autorzy:

Broda, Małgorzata
Rzeszotarska, Barbara

Powiązania:

https://bibliotekanauki.pl/articles/1041295.pdf

Data publikacji:

2006

Wydawca:

Polskie Towarzystwo Biochemiczne

Tematy:

ab initio/DFT calculations
hydrogen bonds
dimer
IR spectra
α,β-dehydroamino acids

Opis:

These comparative studies on the aggregation behaviour of Ac-(Z)-ΔAbu-NMe2 and Ac-L-Abu-NMe2 in carbon tetrachloride were performed by the analysis of their FTIR spectra and by theoretical calculations. The percentage of the monomeric form (α) decreased as concentration increased and this occurred to a higher degree for the (Z)-ΔAbu derivative than for its saturated analogue. The dimerization constant KD, calculated on the basis of the intensity of the monomer and associate bands in the νs(N-H) vibration region, is by three orders of magnitude larger for Ac-(Z)-ΔAbu-NMe2 than for Ac-L-Abu-NMe2. The obtained dimer geometries of the dehydro- compound were calculated by the B3LYP/6-31+G** method.

Źródło:

Acta Biochimica Polonica; 2006, 53, 1; 221-226
0001-527X

Pojawia się w:

Acta Biochimica Polonica

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 86.

Tytuł:

Spin and electron density redistribution upon binding of non-innocent ligand by iron in enzymatic environment: challenges for quantum chemistry

Autorzy:

Brocławik, E.
Borowski, T.
Radoń, M.

Powiązania:

https://bibliotekanauki.pl/articles/1954255.pdf

Data publikacji:

2022-02-01

Wydawca:

Politechnika Gdańska

Tematy:

N,O ligand
Fe
DFT
electron density transfer channels
kanały transferu gęstości elektronowej

Opis:

The quality of the description of a chemical bond between the metal (active site) and the ligand (substrate) critically depends on the electronic processes accompanying the bond formation. However, as far as transition metal centers (TM) in enzymes are considered, most of the properties related to their electronic structure are extremely challenging for quantum chemistry. Especially severe problems appear for the bonding of NO to ferrous sites, e.g. in myoglobin or non-heme enzymes. Therefore, special care has to be shown in the assessment of a quantum chemical method employed with respect to its power in describing the properties of interest. In this work we discuss spin-resolved Fe-NO charge transfers and their relation to the metal spin state, with special attention paid to the interpretation of the bonding between NO and the transition metal center in terms of dative or covalent contributions; furthermore, the impact of spin and the electron transfer on the reactivity of the center is discussed. The stress is put on the role of the coordinating environment in controlling the reaction mechanism via fine-tuning of the spin and the oxidation status of the metal core. This goes in line with the high significance of spin in enzymatic reaction mechanisms (cf. multi-state reactivity proposed for iron enzymes).

Źródło:

TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2014, 18, 3; 255--263
1428-6394

Pojawia się w:

TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 87.

Tytuł:

Tris(8-hydroxyquinoline)aluminium in a polymer matrix as an active layer for green OLED applications

Autorzy:

Sypniewska, Małgorzata
Pokladko-Kowar, Monika
Kaczmarek-Kedziera, Anna
Brumboiu, Iulia E.
Figà, Viviana
Apostoluk, Aleksandra
Song, Peng
Liu, Junyan
Szczesny, Robert
Gondek, Ewa
Derkowska-Zielinska, Beata

Powiązania:

https://bibliotekanauki.pl/articles/2204187.pdf

Data publikacji:

2023

Wydawca:

Polska Akademia Nauk. Stowarzyszenie Elektryków Polskich

Tematy:

Tris(8-hydroxyquinoline)aluminium
OLED
photo-and electro-luminescence
spectroscopic ellipsometry
DFT calculation

Opis:

Tris(8-hydroxyquinoline)aluminium with poly(N-vinylcarbazole) (Alq₃:PVK) or polystyrene sulfonate (Alq₃:PSS) were deposited by spin-coating on glass and silicon substrates. SEM measurements show that relatively smooth thin films were obtained. Fourier transform infrared measurements were performed to confirm the composition of the samples. The optical properties of thin films containing Alq₃:PVK and Alq₃:PSS were characterised using absorption spectroscopy and spectroscopic ellipsometry. It was found that the absorption spectrum of Alq₃:PVK is characterised by four bands, while for Alq₃:PSS only three bands are visible. The photoluminescence of the studied thin layers shows a peak with a maximum at about 500 nm. Additionally, cyclic voltammetry of Alq₃ is also presented. Theoretical density functional theory calculations provide the insight into the interaction and nature of Alq₃:PVK and Alq₃:PSS excited states. Finally, the organic light-emitting diode (OLED) structure based on Alq₃:PVK was fabricated and showed strong electroluminescence with a green emission at 520 nm. The results of the device show that the ITO/PEDOT:PSS/Alq₃:PVK/Ca/Al system can be useful for the production of low-cost OLEDs with Alq₃:PVK as an active layer for future lighting applications.

Źródło:

Opto-Electronics Review; 2023, 31, 2; art. no. e146105
1230-3402

Pojawia się w:

Opto-Electronics Review

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 88.

Tytuł:

Charakterystyka struktury elektronowej heteropolikwasu fosforowolframowego H3PW12O40 modyfikowanego kationem Fe2+
The electronic structure of phosphotungstic (H3PW12O40) heteropolyacids modified by Fe2+ cation

Autorzy:

Niemiec, Piotr Jan

Powiązania:

https://bibliotekanauki.pl/articles/1402364.pdf

Data publikacji:

2020

Wydawca:

Państwowa Wyższa Szkoła Zawodowa w Tarnowie

Tematy:

heteropolikwasy
DFT
analiza strukturalna
heteropolyacids
density functional theory
electronic structure
catalysis
NOCV-SR

Opis:

W pracy zbadano wpływ podstawienia atomu wolframu atomem żelaza w pierwszorzędowej strukturze heteropolikwasu fosforowolframowego o budowie anionu Keggina. Charakterystykę struktury elektronową zmodyfikowanego heteropolikwasu przeprowadzono za pomocą: analizy populacyjnej NBO, całkowitych (PDOS) i parcjalnych (PDOS) widm gęstości stanów, energetyki i charakteru chemicznego orbitali granicznych (HOMO/LUMO) oraz rozmiaru przerwy wzbronionej (gap). Dodatkowo zbadano mechanizm oddziaływania modyfikowanego kationem Fe2+ heteropolikwasu fosforowolframowego z cząsteczką H2O pełniącą rolę środowiska reakcji chemicznej. W większości charakterystyk stwierdzono istotny wpływ wprowadzonego metalu przejściowego na ww. właściwości w stosunku do heteropolikwasu wyjściowego H3PW12O40.
In this paper the influence of substituting the tungsten atom with an iron ion in the primary structure of the phosphotungstic heteropolyacid with the Keggin anion structure was investigated. Characterization of the electronic structure of the modified heteropolyacid was performed using: population analysis according to NBO scheme, total (TDOS) and partial (PDOS) density of states spectra, energy and chemical character of frontier orbitals (HOMO / LUMO) and the size of the HOMO-LUMO band gap. Additionally, the mechanism of interaction between the Fe2+ with H2O molecule, acting as a chemical reaction medium, was investigated. Most cases showed a significant effect of the introduced transition metal ion (Fe2+) on the above-mentioned properties in relation to the nonmodified heteropolyacid H3PW12O40.

Źródło:

Science, Technology and Innovation; 2020, 11, 4; 24-32
2544-9125

Pojawia się w:

Science, Technology and Innovation

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 89.

Tytuł:

Measurement accuracy verification of phasor measurement unit with dynamic phasor estimation

Autorzy:

Arendarski, B.
Rabe, S.
Heineken, W.
Komarnicki, P.

Powiązania:

https://bibliotekanauki.pl/articles/140719.pdf

Data publikacji:

2018

Wydawca:

Polska Akademia Nauk. Czytelnia Czasopism PAN

Tematy:

discrete Fourier transform (DFT)
dynamic phasor
measurement accuracy
phasor measurement unit (PMU)
power system

Opis:

Power systems that are highly loaded, especially by a stochastic supply of renew- ables and the presence of storages, require dynamic measurements for their optimal control. Phasor measurement units (PMUs) can be used to capture electrical parameters of a power system. Standards on the PMU dynamic performance have been modified to incorporate their new dynamic mode of operation. This paper examines the PMU dynamic performance and proposes essential algorithms for measurement accuracy verification. Measurements of dynamic input signals, which vary in amplitude or frequency, were taken during au- tomated tests of two PMUs. The test results are presented and expounded with further recommendation for the performance requirements. This paper also presents and examines applied testing procedures with relevance to the specifications of the IEEE Standard for Synchrophasor C37.118.1™-2011 and its amendment C37.118.1a™-2014.

Źródło:

Archives of Electrical Engineering; 2018, 67, 3; 529--543
1427-4221
2300-2506

Pojawia się w:

Archives of Electrical Engineering

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 90.

Tytuł:

Quantum Chemical Study of Aminonitrocyclopentanes as Possible High Energy Density Materials (HEDMs)

Autorzy:

Bai, J.
Chi, W. J.
Li, L. L.
Yan, T.
Wen, X. E.
Li, B. T.
Wu, H. S.
Ma, F. L.

Powiązania:

https://bibliotekanauki.pl/articles/358101.pdf

Data publikacji:

2013

Wydawca:

Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego

Tematy:

cyclopentane derivatives
high energy density materials
impact sensitivity
quantum chemistry
DFT
available free space

Opis:

Nitro and amine groups were introduced into the cyclopentane skeleton, and the heats of formation, detonation performance, bond dissociation energies, and impact sensitivity for these aminonitrocyclopentanes were calculated in detail at the B3LYP/6-311G** level. The results show that all of the derivatives have negative heats of formation, which are influenced by the position of the substituent groups. Their stabilities were estimated and analyzed according to their bond dissociation energies and calculated characteristic H50 values. Most of the compounds were found to have a lower impact sensitivity than HMX. Furthermore, the detonation velocities and detonation pressures were predicted via the Kamlet-Jacobs equation. Of all these aminonitrocyclopentanes, E has the best detonation properties (ρ = 2.05 g/cm3, D = 9.11 m/s, P = 39.62 GPa) and can be considered as a candidate high energy density material.

Źródło:

Central European Journal of Energetic Materials; 2013, 10, 4; 467-480
1733-7178

Pojawia się w:

Central European Journal of Energetic Materials

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 91.

Tytuł:

Analizator do spektroskopii wysokoimpedancyjnej wykorzystujący DFT w detekcji fazoczułej
High impedance analyzer using DFT for phase-sensitive detection

Autorzy:

Hoja, J.
Lentka, G.

Powiązania:

https://bibliotekanauki.pl/articles/153153.pdf

Data publikacji:

2006

Wydawca:

Stowarzyszenie Inżynierów i Techników Mechaników Polskich

Tematy:

DFT w detekcji fazoczułej
analizator do spektroskopii wysokoimpedancyjnej
high impedance analyzer
phase-sensitive detection

Opis:

W pracy przedstawiono metodę pomiaru impedancji opartą na próbkowaniu sygnałów oraz wyznaczaniu ich parametrów z zastosowaniem algorytmów cyfrowego przetwarzania sygnałów. Zastosowano dyskretną transformację Fouriera do wyznaczania składowych ortogonalnych sygnałów pomiarowych. Przeprowadzono analizę dokładności pomiaru impedancji uwzględniającą rozdzielczość przetworników a/c, amplitudę sygnału pomiarowego, liczbę zebranych próbek w czasie pomiaru oraz stosunek składowych ortogonalnych impedancji mierzonej. Wyniki badań symulacyjnych pozwoliły na zrealizowanie analizatora do spektroskopii wysokoimpedancyjnej w szerokim zakresie częstotliwości od bardzo niskich 100 ΜHz do 1MHz.
The paper presents the impedance measurement method based on signal sampling and determining their parameters with the aid of algorithms of digital signal processing. The Discrete Fourier Transform was used to determine orthogonal parts of measurement signals. The analysis of measurement accuracy was performed taking into account the resolution of the AD converters, measurement signal amplitude, the number of acquired samples during the measurement process and the ratio of orthogonal parts of the measured impedance. The results of simulations have allowed to make high impedance analyzer working in a wide frequency range starting from 100?Hz to 1MHz.

Źródło:

Pomiary Automatyka Kontrola; 2006, R. 52, nr 6, 6; 45-47
0032-4140

Pojawia się w:

Pomiary Automatyka Kontrola

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 92.

Tytuł:

„Ab initio” study of helium atoms immobilization in UO2 crystals

Autorzy:

Dąbrowski, L.
Szuta, M.

Powiązania:

https://bibliotekanauki.pl/articles/146654.pdf

Data publikacji:

2012

Wydawca:

Instytut Chemii i Techniki Jądrowej

Tematy:

uranium
dioxide
DFT+U
LDA
GGA
ABINIT
over-barrier jumps
incorporated helium
harmonic oscillator

Opis:

We present density functional theory (DFT) calculation results concerning the uranium dioxide crystals with a helium atom incorporated in the octahedral interstitial position. "Ab initio" calculations were performed using the Wien2k program package. For comparison, a pseudo-potential approach in the generalized gradient approximation was applied using the ABINIT program package. To compute the unit cell parameters 13 atom super-cell was chosen. Parameters of the potential barrier, which the helium atom has to overcome while jumping to the next octahedral interstitial position, were calculated by the help of both the program packages. The results, obtained using two different program packages, are shown in the table and presented graphically. For the so described parameters, the quantum mechanical movement of the helium atom around the equilibrium position is considered. The parameters of Schrödinger's equation are collected in Table 2, while the results of mean square deviation and thermal occupation of energetic levels are presented in a graph. It is established that the helium atoms are located (with an accuracy of several percent of lattice constant) nearby the equilibrium position and form a local bound state. Applying a two site-model, we evaluated the time for an over-barrier jump. Graphically presented results show that the helium atom over-barrier jump is not possible even for temperatures as high as 1200 K. Influence of potential barrier height on the jump time was also considered.

Źródło:

Nukleonika; 2012, 57, 3; 337-343
0029-5922
1508-5791

Pojawia się w:

Nukleonika

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 93.

Tytuł:

Bonding xenon on the surface of uranium dioxide single crystal

Autorzy:

Dąbrowski, L.
Szuta, M.

Powiązania:

https://bibliotekanauki.pl/articles/147186.pdf

Data publikacji:

2013

Wydawca:

Instytut Chemii i Techniki Jądrowej

Tematy:

noble gases
uranium dioxide
chemical bond
density functional theory (DFT)
generalized gradient approximation (GGA)

Opis:

We present density functional theory (DFT) calculation results of xenon atom interaction with the surface of uranium dioxide single crystal. A pseudo-potential approach in the generalized gradient approximation (GGA) was applied using the ABINIT program package. It has been revealed that close to the surface a potential well is formed for xenon atom due to its interaction with the atoms of oxygen and uranium. Depth and shape of the well is the subject of “ab initio” calculations. The calculations were performed both for the case of oxygenic and metallic surfaces. It has been shown, that the potential well for the oxygenic surface is deeper than for the metallic surface.

Źródło:

Nukleonika; 2013, 58, 4; 453-458
0029-5922
1508-5791

Pojawia się w:

Nukleonika

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 94.

Tytuł:

Systematic errors of the LIDFT method: analytical form and verification by a Monte Carlo method

Autorzy:

Borkowski, J.

Powiązania:

https://bibliotekanauki.pl/articles/221176.pdf

Data publikacji:

2012

Wydawca:

Polska Akademia Nauk. Czytelnia Czasopism PAN

Tematy:

LIDFT
multifrequency signal
interpolated DFT
spectrum estimation
zero padding
unit circle
approximation by polygon

Opis:

This paper derives analytical formulas for the systematic errors of the linear interpolated DFT (LIDFT) method when used to estimating multifrequency signal parameters and verifies this analysis using Monte-Carlo simulations. The analysis is performed on the version of the LIDFT method based on optimal approximation of the unit circle by a polygon using a pair of windows. The analytical formulas derived here take the systematic errors in the estimation of amplitude and frequency of component oscillations in the multifrequency signal as the sum of basic errors and the errors caused by each of the component oscillations. Additional formulas are also included to analyze particular quantities such as a signal consisting of two complex oscillations, and the analyses are verified using Monte-Carlo simulations.

Źródło:

Metrology and Measurement Systems; 2012, 19, 4; 673-684
0860-8229

Pojawia się w:

Metrology and Measurement Systems

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 95.

Tytuł:

Moc opisowa drzew niezdatności z zależnościami czasowymi
Expressive power of probabilistic fault trees with time dependencies

Autorzy:

Magott, J.

Powiązania:

https://bibliotekanauki.pl/articles/257687.pdf

Data publikacji:

2009

Wydawca:

Sieć Badawcza Łukasiewicz - Instytut Technologii Eksploatacji - Państwowy Instytut Badawczy

Tematy:

sieć PERT
dynamiczne drzewa niezdatności
DDN
PDNZC
PERT network
dynamic fault tree
DFT
PFTTD

Opis:

W pracy przeanalizowano moc opisową probabilistycznych drzew niezdatności z zależnościami czasowymi (PDNZC) w wyrażaniu sieci PERT i dynamicznych drzew niezdatności (DDN). PDNZC składają się z bramek, zdarzeń oraz połączeń bramek ze zdarzeniami. Bramki podzielone są na dwie zasadnicze kategorie, a mianowicie: uogólniające i przyczynowe. W pracy stosowane są tylko bramki przyczynowe. Przedstawiono te bramki przyczynowe, które są używane w ilustracji mocy opisowej PDNZC. Pokazano jak za pomocą PDNZC można wyrazić sieci PERT. Badając moc opisową PDNZC w wyrażaniu DDN, skoncentrowano się na reprezentacji następujących bramek dynamicznych: priorytetowej AND, komponentów rezerwowych, funkcjonalnej zależności.
Descriptive Power of Probabilistic Fault Trees with Time Dependencies (PFTTD) in expressing PERT networks and Dynamic Fault Trees (DFT) are analysed in the paper. PFTTD are combined from events, gates, and connections between them. The gates are divided into two categories, namely, causal and general. A causal gate is characterised by delay times between causes (input events) and effect (output event). The output event of the generalisation gate is a combination of input events. In the paper, only causal gates are used. How to model PERT networks by PFTTD is shown. Th paper illustrates how PFTTD can model the following gates of DFT: priority AND, spare with cold stand-by, and functional dependency. In future research, the decision power of PFTTD will be studied. Algorithms for finding quantitative characteristics of PFTTD will be based on achievements of PERT networks and reliability theory.

Źródło:

Problemy Eksploatacji; 2009, 4; 33-40
1232-9312

Pojawia się w:

Problemy Eksploatacji

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 96.

Tytuł:

Conformational properties of N-acetyl-L-alanine N',N'-dimethylamide.

Autorzy:

Siodłak, Dawid
Rzeszotarska, Barbara
Broda, Małgorzata

Powiązania:

https://bibliotekanauki.pl/articles/1043329.pdf

Data publikacji:

2004

Wydawca:

Polskie Towarzystwo Biochemiczne

Tematy:

ab initio/DFT calculations
N-alkylpeptides
β-turns
alanine derivative
N',N'-dimethylamides
peptide design

Opis:

Ab initio/DFT analysis of the conformational properties of free Ac-Ala-NMe2 (N-acetyl-L-alanine-N',N'-dimethylamide) in terms of the N-H···O, N-H···N, C-H···O hydrogen bonds and Cδ+ = Oδ- dipole attractions was performed. The Ala residue combined with the C-terminal tertiary amide prefers an extended conformation and that characteristic of the (i + 1)th position of the βVIb turn. These can be easily remodelled into a structure compatible with the (i + 1)th position of the βII/βVIa turn. The residue has also the potential to adopt the conformation accommodated at both central positions of the βIII/βIII' turn or the (i + 1)th position of the βI/β'I turn.

Źródło:

Acta Biochimica Polonica; 2004, 51, 1; 137-143
0001-527X

Pojawia się w:

Acta Biochimica Polonica

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 97.

Tytuł:

Diffusion of helium in the perfect uranium and thorium dioxide single crystals

Autorzy:

Dąbrowski, L.
Szuta, M.

Powiązania:

https://bibliotekanauki.pl/articles/147700.pdf

Data publikacji:

2013

Wydawca:

Instytut Chemii i Techniki Jądrowej

Tematy:

uranium
thorium dioxide
diffusion
tunneling
DFT+U
generalized gradient approximation (GGA)
potential barrier
incorporated helium

Opis:

We present quantum-mechanical evaluation of helium diffusion coefficient in the crystalline UO2 and ThO2. Parameters assignment of Schrödinger’s equation were done using the crystal field potentials which were obtained applying the density functional theory (DFT). “Ab initio” calculations were performed using the Wien2k program package. To compute the unit cell parameters the 13 atom super-cell was chosen. Applying two-site model we evaluated the time for an over-barrier jump and diffusion of interstitial He. The obtained values for diffusion coefficient are compared with the experimentally obtained values and with the theoretical values of other authors. In addition, it is simultaneously shown that helium diffusion in these materials is a quantum diffusion.

Źródło:

Nukleonika; 2013, 58, 2; 295-300
0029-5922
1508-5791

Pojawia się w:

Nukleonika

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 98.

Tytuł:

Fornasini-Marchesini 2-D State Space Models: Transfer Function Computation Via the Dft

Autorzy:

Antoniou, G.
Emmons, K.

Powiązania:

https://bibliotekanauki.pl/articles/911185.pdf

Data publikacji:

2000

Wydawca:

Uniwersytet Zielonogórski. Oficyna Wydawnicza

Tematy:

teoria systemów
transformata Fouriera
two dimensions system theory
Fourier transform
DFT algorithm
Fornasini-Marchesini's model

Opis:

A new algorithm is presented for the computation of the coefficients of the determinantal polynomial and the coefficients of the adjoint polynomial matrix of a given two-dimensional (2-D) state space model of Fornasini-Marchesini type. The algorithm has been implemented in Matlab and uses the discrete Fourier transform (DFT). The simplicity and efficiency of the technique are illustrated by two examples.

Źródło:

International Journal of Applied Mathematics and Computer Science; 2000, 10, 2; 321-331
1641-876X
2083-8492

Pojawia się w:

International Journal of Applied Mathematics and Computer Science

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 99.

Tytuł:

Mössbauer study of a tetrakis (pentafl uorophenyl) porphyrin iron (III) chloride in comparison with the fluorine unsubstituted analogue

Autorzy:

Kaczmarzyk, T.
Dziedzic-Kocurek, K.
Rutkowska, I.
Dziliński, K.

Powiązania:

https://bibliotekanauki.pl/articles/146091.pdf

Data publikacji:

2015

Wydawca:

Instytut Chemii i Techniki Jądrowej

Tematy:

catalytic activity
DFT calculations
electronic structure
iron(III)-[tetrakis (pentafl uorophenyl)]
Mössbauer spectroscopy
porphyrin chloride

Opis:

Mössbauer investigations, in association with density functional theory (DFT) calculations, have been conducted for the molecular and electronic structures of iron (III) [tetrakis (pentafl uorophenyl)] porphyrin chloride [(F20TPP)Fe:Cl], as a Fe(III)-tetraphenylporphyrin complex containing chloride axial ligand and substituted hydrogen atoms by fl uorine ones in the four phenyl rings, in comparison with its fl uorine unsubstituted analogue [(TPP)Fe:Cl]. It was found that the parameters of Mössbauer spectra of both complexes are close to one another, and correspond to the high-spin state of Fe(III) ions, but they show the different temperature dependence and the quadrupole doublets in Mössbauer spectra show different asymmetry at low temperatures. Results of DFT calculations are analyzed in the light of catalytic activity of the halogenated complex.

Źródło:

Nukleonika; 2015, 60, 1; 57-61
0029-5922
1508-5791

Pojawia się w:

Nukleonika

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 100.

Tytuł:

Conformational properties of N-acetyl-N-methyl-α,β-dehydroalanine N-methylamide

Autorzy:

Macedowska, Agnieszka
Siodłak, Dawid
Rzeszotarska, Barbara

Powiązania:

https://bibliotekanauki.pl/articles/1041296.pdf

Data publikacji:

2006

Wydawca:

Polskie Towarzystwo Biochemiczne

Tematy:

ab initio/DFT calculations
N-alkylpeptides
cis-trans isomerisation
α,β-dehydroamino acids
peptide design

Opis:

The conformational properties of Ac-Δ(Me)Ala-NHMe (N-acetyl-N-methyl-α,β-dehydroalanine N'-methylamide), as the simplest model of N-methyl-α,β-dehydroamino acids, was examined with theoretical methods and in comparison with Ac-ΔAla-NHMe and Ac-ΔAla-NMe2. The N-terminal amide of the Δ(Me)Ala residue easily adopts the configuration cis and the torsion angles φ, ψ are highly flexible. The Δ(Me)Ala residue is a conformational flexibilizer as compared to the parent ΔAla, which is a conformational stiffener. This seems to be the reason why Δ(Me)Ala is found in small natural cyclic peptides, where it ensures the conformational flexibility necessary for biological action.

Źródło:

Acta Biochimica Polonica; 2006, 53, 1; 227-232
0001-527X

Pojawia się w:

Acta Biochimica Polonica

Dostawca treści:

Biblioteka Nauki

/5

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