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Wyszukujesz frazę "density functional theory (DFT)" wg kryterium: Temat

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    Wyświetlanie 1-8 z 8
    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
    Artykuł
    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
    Artykuł
    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
    Artykuł
    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
    Artykuł
    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
    Artykuł
    Tytuł:
    Theoretical investigations into the Spectrophotometrically Analyzed Niobium (V)-6-Chloro-3-hydroxy-7-methyl-2-(2’-thienyl)-4H-chromen-4-one Complex
    Autorzy:
    Dhonchak, Chetna
    Agnihotri, Nivedita
    Azam, Mohammad
    Javed, Saleem
    Muthu, Sambantham
    Al-Resayes, Saud I.
    Min, Kim
    Powiązania:
    https://bibliotekanauki.pl/articles/27315655.pdf
    Data publikacji:
    2023
    Wydawca:
    Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
    Tematy:
    Niobium
    6-Chloro-3-hydroxy-7-methyl-2-(2’-thienyl)-4H-chromen-4-one
    spectrophotometry
    DFT
    density functional theory
    MEP
    molecular electrostatic potential
    Opis:
    Pentavalent niobium cation forms a stable yellow-colored binary complex with 6-chloro-3-hydroxy-7-methyl-2-(2’- thienyl)-4H-chromen-4-one (CHMTC) in the ratio of 1:2. The complex is quantitatively extractable into carbon tetrachloride from HClO4 solution maintained at pH 1.26–1.75 and strictly adheres to Beer’s law as verified by the Ringbom plot with an optimized range of determination as 0.385–1.211 ppm of Nb(V). The ligand-metal complex system shows good precision, accuracy, sensitivity, and selectivity and handles satisfactorily the analysis of several samples of varying complexity. The results are highly reproducible as confirmed by statistical data. The stability of the complex is theoretically confirmed with the help of HOMO-LUMO values and the energy gap [for CHMTC, ΔEgap = 3.62 V and for Nb(V)-CHMTC Complex, ΔEgap = 2.97 eV]. The reactivity descriptors were calculated for detailed computational study to probe into the chemical behavior of the studied ligand and its complex. Further, mapped electrostatic potential diagrams help in justifying the donor sites of CHMTC ligand which is in accordance with the analytical findings.
    Źródło:
    Polish Journal of Chemical Technology; 2023, 25, 3; 63--70
    1509-8117
    1899-4741
    Pojawia się w:
    Polish Journal of Chemical Technology
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Stability phase diagram of the Ir-Pt solid solution - numerical modelling from first principles
    Autorzy:
    Woźniakowski, A.
    Deniszczyk, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/333620.pdf
    Data publikacji:
    2013
    Wydawca:
    Uniwersytet Śląski. Wydział Informatyki i Nauki o Materiałach. Instytut Informatyki. Zakład Systemów Komputerowych
    Tematy:
    ab-initio phase diagram modelling
    Monte Carlo (MC) simulations
    density functional theory
    DFT
    obliczenia ab initio
    modelowanie diagramu fazowego
    symulacja Monte Carlo
    teoria funkcjonału gęstości
    Opis:
    First principles based numerical methods are used to determine the phase stability diagram of the Ir–Pt solid solution with A1-type crystal structure. Ising-like cluster expansion formalism was used to construct the lattice Hamiltonian. Phase diagram was calculated with the use of Monte Carlo simulations. Miscibility gap in this system was predicted. Calculated consolute temperature (TC) is about 1250 K at 50% of platinum when excess vibrational contribution to the free energy was included. The result is in good quantitative agreement with experimental data.
    Źródło:
    Journal of Medical Informatics & Technologies; 2013, 22; 265-269
    1642-6037
    Pojawia się w:
    Journal of Medical Informatics & Technologies
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Właściwości wewnątrzcząsteczkowych wiązań wodorowych w wybranych N-tlenkach pochodnych chinoliny
    Intramolecular hydrogen bonds properties in selected N-oxides of quinoline derivatives
    Autorzy:
    Jezierska, Aneta
    Panek, Jarosław J.
    Błaziak, Kacper
    Powiązania:
    https://bibliotekanauki.pl/articles/171511.pdf
    Data publikacji:
    2019
    Wydawca:
    Polskie Towarzystwo Chemiczne
    Tematy:
    DFT
    teoria funkcjonału gęstości
    MP2
    metoda rachunku zaburzeń drugiego rzędu Møllera-Plesseta
    CPMD
    dynamika molekularna Cara-Parrinello
    wewnątrzcząsteczkowe wiązanie wodorowe
    N-tlenki pochodnych chinoliny
    density functional theory
    Møller-Plesset second order perturbation method
    Car-Parrinello molecular dynamics
    intramolecular HB
    N-oxides of quinoline derivatives
    Opis:
    In the current article we would like to summarize our research shedding light onto properties of intramolecular hydrogen bonds present in N-oxide quinoline derivatives. The compounds for the current study were chosen to contain diverse types of hydrogen bonds. Therefore, in the current study we analyze three kinds of hydrogen bonding and their properties. It is well known, that the presence of intramolecular hydrogen bonds stabilizes conformations of molecules. Substituent effects (inductive and steric) influence the strength of the H-bonding as well as its features. Moreover, the intramolecular hydrogen bond in the studied N-oxides belongs to the family of resonance assisted hydrogen bonds (RAHB). Our short overview presents the summary of results obtained for twelve N-oxides of quinoline derivatives. Quantum-chemical simulations were performed on the basis of static models (classical DFT and MP2 approaches) as well as ab initio molecular dynamics (Car-Parrinello MD). The metadynamics method was applied to reproduce the maps of free energy for the motion of the bridged proton. The computations were performed in the gas and in the crystalline phases. Electronic ground state is a natural framework in which chemical compounds exist most of the time. However, in many chemical species we observe a spontaneous internal reorganization of their chemical bonds and atoms e.g. proton transfer phenomenon and the appearance of tautomeric forms already in the ground state. Therefore, it was interesting to investigate some N-oxides in the excited electron state knowing that they exhibit excited- state-induced proton transfer (ESIPT effect). At the end of the article we draw some conclusions related to the intramolecular H-bond properties present in the discussed N-oxides of quinoline derivatives.
    Źródło:
    Wiadomości Chemiczne; 2019, 73, 1-2; 75-95
    0043-5104
    2300-0295
    Pojawia się w:
    Wiadomości Chemiczne
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-8 z 8

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