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    Wyświetlanie 1-44 z 44
    Tytuł:
    A Hybrid Density Functional Study on PuN
    Autorzy:
    Yang, Rong
    Tang, Bin
    Gao, Tao
    Powiązania:
    https://bibliotekanauki.pl/articles/1029819.pdf
    Data publikacji:
    2018-01
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    plutonium mononitride
    density-functional theory
    hybrid functional
    Opis:
    The structural, magnetic, electronic, dynamical and thermodynamic properties of PuN have been studied within the frameworks of the density-functional theory, DFT+U and hybrid DFT. The calculations have been performed using the full-potential-linearized augmented plane-wave method. The ferromagnetic and antiferromagnetic configurations are considered in this work. The lattice constants, bulk moduli, densities of states, and thermodynamic data have been computed and compared to available experimental data and other theoretical calculations published in the literature. Total energy results obtained with DFT+U and hybrid DFT indicate that the ground state of PuN is antiferromagnetic, in agreement with experiment. The chemical bonds between Pu and N have a mixture of covalent and ionic components, but the ionic character is stronger than covalent character. The phonon dispersion curves and the optical-mode frequencies are also reported. At last, the effect of spin-orbit coupling on the structural, magnetic, and electronic properties of PuN has been discussed.
    Źródło:
    Acta Physica Polonica A; 2018, 133, 1; 32-38
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Adsorption of hydrated Fe(OH)2+ on the kaolinite surface: A density functional theory study
    Autorzy:
    Wu, Hongqiang
    Miao, Yuqi
    Long, Qibang
    Yan, Huashan
    Li, Yong
    Qiu, Sen
    Wu, Hao
    Zhao, Guanfei
    Qiu, Tingsheng
    Powiązania:
    https://bibliotekanauki.pl/articles/27323639.pdf
    Data publikacji:
    2023
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    kaolinite
    adsorption
    Fe
    density functional theory
    Opis:
    The present study employed density functional theory (DFT) to analyze the adsorption configuration and mechanism of Fe(OH)2+ on the kaolinite (001) surface. The findings demonstrated that Fe(OH)2(H2O)4+ is the main type in which hydrated Fe(OH)2+ can be found in aqueous solution. On the surface of kaolinite, Fe(OH)2(H2O)4+ will be adsorbed. There are two forms of adsorption: outer-sphere and inner-sphere coordination (monodentate/bidentate) adsorption. Fe(OH)2(H2O)4+ has a moderate propensity to adsorb on the alumina octahedral sheet of kaolinite when the outer-sphere coordination adsorption takes place. In cases of inner-sphere coordination adsorption, Fe exhibits a tendency to form monodentate adsorption compounds in conjunction with Ou atoms. Additionally, it prefers to create bidentate adsorption compounds through coordination with both Ot and Ou atoms. The adsorption mechanism analysis results show that the ionic property of Fe atom decreases after outer-sphere coordination adsorption. After inner-sphere coordination adsorption, some electrons of Fe atom are transferred to the surface O atom. The presence of electrons between the Fe and O atoms enhances the formation of bonds, hence enhancing the covalent nature of the Fe-O bond. Theoretical FT-IR (Fourier transform infrared spectroscopy) calculations show that the formation of Fe-O chemical bonds. Because of the lower adsorption energy and more chemical bonds, hydrate Fe(OH)2+ is more likely to be bidentate adsorbed on the kaolinite surface.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2023, 59, 6; art. no. 174415
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Synthesis and Theoretical Studies of a New High Explosive, N,N,-Bis(3-aminofurazan-4-yl)-4,4´-diamino- 2,2´,3,3´,5,5´,6,6´-octanitroazobenzene
    Autorzy:
    Jing, S.
    Liu, Y.
    Liu, D.
    Guo, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/358642.pdf
    Data publikacji:
    2015
    Wydawca:
    Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego
    Tematy:
    BAFDAONAB
    density functional theory
    detonation properties
    Opis:
    A new high energy, low sensitivity material N,N,-bis(3-aminofurazan- 4-yl)-4,4´-diamino-2,2´,3,3´,5,5´,6,6´-octanitroazobenzene (BAFDAONAB) was synthesized from 4-chlorobenzoic acid and diaminofurazan. The structure of BAFDAONAB was characterized by FT-IR, NMR and Elemental Analyses and its purity was determined by HPLC. The optimized structure and thermodynamic parameters were obtained at the DFT- B3LYP/6-31+G** theoretical level. Its detonation properties were also predicted by the formulae of Kamlet-Jacobs and the Monte-Carlo method. The results show that the density, heat of formation, detonation velocity, detonation pressure, impact sensitivity and purity were 1.93 g/cm3, 4487.44 kJ/mol, 9.01 km/s, 35.03 GPa, 63 cm and 99.3%, respectively. In addition, the compound was an insensitive high explosive which could meet the requirements of high energetic materials.
    Źródło:
    Central European Journal of Energetic Materials; 2015, 12, 4; 745-755
    1733-7178
    Pojawia się w:
    Central European Journal of Energetic Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Density functional simulation of metal oxides: $Al_2O_3$ and $Fe_3O_4$
    Autorzy:
    Łodziana, Z.
    Powiązania:
    https://bibliotekanauki.pl/articles/2028983.pdf
    Data publikacji:
    2004
    Wydawca:
    Politechnika Gdańska
    Tematy:
    density functional theory
    metal oxides
    alumina
    magnetite
    Opis:
    The study of the metal oxides is a rapidly developing area of research. Below a theoretical method based on the density functional theory, common in studying ceramics, is briefly presented. Application of the theory to the surface and the bulk properties of alumina and magnetite are presented. Relaxation mechanism of two different surfaces of alumina and the (100) surface of Fe3O4 are shown. The mutual stability of the ? and ? phases of Al2O3 is calculated.
    Źródło:
    TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2004, 8, 4; 561-572
    1428-6394
    Pojawia się w:
    TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Density functional theory study of H2O adsorption on different sphalerite surfaces
    Autorzy:
    Deng, Zheng-bin
    Tong, Xiong
    Huang, Ling-yun
    Xie, Xian
    Powiązania:
    https://bibliotekanauki.pl/articles/110593.pdf
    Data publikacji:
    2019
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    density functional theory
    sphalerite
    water adsorption
    hydrophobicity
    Opis:
    Effects of In, Ge, Fe substitution in the lattice of sphalerite on wettability were usually ignored, therefore the optimal flotation condition could be difficult to find due to lacking of sufficient theoretical study on water adsorption, resulting lower recoveries of different sphalerites. Adsorption of H2O on different sphalerite surfaces was studied using density functional theory (DFT) method. All computational models were built in a vacuum environment to eliminate the effects of oxygen and other factors. H2O molecule prefers to stay with ideal sphalerite, indium-beard sphalerite, germanium-beard sphalerite and marmatite surfaces rather than water. Compared with ideal sphalerite surface, Fe atom improves the hydrophilicity of surface, while In and Ge atoms reduce the hydrophilicity.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2019, 55, 1; 82-88
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Insights into the interaction between octyl hydroxamic acid and the rutile surface activated by lead ion
    Autorzy:
    Cao, Qinbo
    Chen, Xiumin
    Zou, Heng
    Yu, Xingcai
    Powiązania:
    https://bibliotekanauki.pl/articles/1845214.pdf
    Data publikacji:
    2020
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    flotation
    rutile
    activation
    density functional theory
    adsorption
    Opis:
    The flotation of rutile can be enhanced using lead ion as an activator. However, the binding behavior of collector on the activated rutile surface is still not fully understood. In this work, flotation and theoretical calculation approaches were employed to evaluate the activation behavior of lead ion in the flotation of rutile with octyl hydroxamic acid (OHA). Flotation results indicated that the activation flotation with lead ion should be conducted at pH 6.5. The binding features of OHA molecule on the inactivated and Pb-activated rutile surfaces were both investigated by density functional theory (DFT) studies. The OHA molecule may dissociate into OHA− anion on the inactivated rutile surface, generating a new Ti–O bond. Differently, the chelate complex of Pb-OHA anion was generated on the activated rutile surface, producing two Pb–O bonds. The adsorption of OHA onto the activated rutile surface was more stable than that on the inactivated rutile surface, due to the formation of more chemical bonds on the activated rutile surface. The DFT calculation results delineated the role of Pb2+ in the rutile flotation with OHA.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2020, 56, 5; 928-938
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Flotation separation of cervantite from quartz
    Autorzy:
    Wang, J.
    Hua, Y.
    Yu, S.
    Xiao, J.
    Xu, L.
    Wang, Z.
    Powiązania:
    https://bibliotekanauki.pl/articles/110941.pdf
    Data publikacji:
    2017
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    cervantite
    quartz
    dodecylamine
    flotation
    density functional theory
    Opis:
    Flotation separation of cervantite (Sb2O4) from quartz was investigated using dodecylamine (DDA) as a collector. Experiments were conducted on single minerals and on a synthetic mixture of quartz and cervantite. Flotation separation mechanisms were investigated using the zeta potential technique, solution chemistry principles, density functional calculations and Fourier Transform Infrared (FT-IR) spectroscopy. The results indicated that DDA, primarily in the form of molecules, exhibited excellent performance in flotation of cervantite and quartz at pH 10.5. The adsorption energy of the DDA molecules on the cervantite surface was greater than the adsorption energy of water molecules, while the adsorption energy of DDA on the quartz surface was less than the adsorption energy of water molecules. DDA molecules can be adsorbed on the quartz surface to a certain extent, but it was difficult for the same molecule to be adsorbed on the cervantite surface in the pulp. This resulted in flotation of quartz. DDA molecules were adsorbed on quartz not only through physical adsorption but also by hydrogen bonding. However, cervantite could not be floated at pH 10.5 since adsorption of DDA molecules occurred through weak physical bonds on cervantite.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2017, 53, 2; 1119-1132
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Interaction of sulfuric acid with dolomite (104) surface and its impact on the adsorption of oleate anion: a DFT study
    Autorzy:
    Cao, Qinbo
    Zou, Heng
    Chen, Xiumin
    Yu, Xingcai
    Powiązania:
    https://bibliotekanauki.pl/articles/1449558.pdf
    Data publikacji:
    2020
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    dolomite
    adsorption
    oleate
    depressor
    density functional theory
    Opis:
    Sulfuric acid $(H_2SO_4)$ is a specific depressor for apatite rather than for dolomite. The $H_2SO_4$ treated dolomite can still be floated effectively by oleate. However, the role of $H_2SO_4$ in the adsorption of oleate onto dolomite surface remains unclear. In this work, density functional theory calculations were conducted to probe the interactions among sulfate anion ($SO_4^{2−}$), oleate anion and the dolomite surface. The adsorption behaviors of $SO_4^{2−}$ anion onto the perfect and $CO_3$-defect dolomite surfaces were compared. Such results show that $SO_4^{2−}$ anion could only adsorb onto the defective dolomite surface, where it bonded with a $Ca$ atom. The remaining $Ca$ and $Mg$ atoms at the defect site could further react with the oleate anion, generating new $Ca$/$Mg–O$ ionic bond. In this regard, oleate and $SO_4^{2−}$ anions may both present on the dolomite surface. This phenomenon accounts for the flotation of $H_2SO_{4-}$treated dolomite.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2020, 56, 1; 34-42
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Study of flocculation performance and mechanism of ultrafine montmorillonite particles with NPAM
    Autorzy:
    Wang, Lujun
    Min, Fanfei
    Chen, Jun
    Wang, Ting
    Zhou, Zhuang
    Powiązania:
    https://bibliotekanauki.pl/articles/2146901.pdf
    Data publikacji:
    2022
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    montmorillonite
    flocculant
    nonionic polyacrylamide
    density functional theory
    Opis:
    Ultrafine montmorillonite particles are the main clay minerals in industrial wastewater. In order to explore the flocculation performance and mechanism of flocculant with montmorillonite, the effects of nonionic polyacrylamide (NPAM) dosage and molecular weight on flocculation effect were studied using a flocculation sedimentation experiment. The morphology of flocs was observed by metallographic microscope and scanning electron microscope, and the microscopic adsorption mechanism was studied utilizing density functional theory (DFT). The results show that the best reagent system for the montmorillonite sample is that the molecular weight of NPAM is 14 million and the added amount is 100 g/t. The floc size increases with rising NPAM dosage, forming a unique multi-level compact space network structure through polymer bridging. The adsorption energy of acrylamide on the Na-(001) surface of montmorillonite is -108.81 kJ/mol, which is significantly higher than -50.66 kJ/mol on the None-(001) surface. Hydrogen bonding is not the main reason for the adsorption of acrylamide on the montmorillonite surface. NPAM mainly causes the flocculation and sedimentation of montmorillonite through the processes of polymer bridging and electrostatic attraction. This study can provide a theoretical basis for the design and synthesis of new flocculants.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2022, 58, 3; art. no. 147790
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Aminonitronaphthalenes as Possible High Energy Density Materials
    Autorzy:
    Murawski, R. J.
    Ball, D. W.
    Powiązania:
    https://bibliotekanauki.pl/articles/358002.pdf
    Data publikacji:
    2015
    Wydawca:
    Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego
    Tematy:
    high energy density materials
    aminonitronaphthalenes
    density functional theory calculations
    Opis:
    As part of a series of studies evaluating the thermodynamic properties of new potential high energy materials, a series of calculations was performed on a variety of naphthalene molecules having amino and nitro groups. Calculations on seven aminonitronaphthalene molecules were performed, determining their minimum-energy geometries, vibrational frequencies, and energies. Enthalpies of formation were determined using atomization reactions, and subsequently enthalpies of combustion or decomposition were determined. Specific enthalpies of decomposition ranged from 4.1-4.8 kJ/g, while specific enthalpies of combustion ranged more widely, from 13 to almost 21 kJ/g. Some detonation properties of some of the derivatives rival those of current HEDMs.
    Źródło:
    Central European Journal of Energetic Materials; 2015, 12, 1; 3-12
    1733-7178
    Pojawia się w:
    Central European Journal of Energetic Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Hydrogen storage on graphene sheet: physisorption, diffusion and chemisorbed pathways by first principles calculations
    Magazynowanie wodoru na arkuszu grafenu: analiza ścieżek fizykosorpcji, dyfuzji i chemisorpcji metodą obliczeń ab initio
    Autorzy:
    Costanzo, F.
    Silvestrelli, P.L.
    Ancilotto, F.
    Powiązania:
    https://bibliotekanauki.pl/articles/356177.pdf
    Data publikacji:
    2012
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    density functional theory
    first principles
    physisorption and chemisorption
    Opis:
    Hydrogen is frequently touted as the "fuel of the future" because of its huge potential as clean energy source, although the large-scale adoption of this technology has yet to be realized. One of the remaining barriers to the utilization of hydrogen energy is an efficient and inexpensive means of hydrogen storage. In this work we investigate the nature of this process by first principle calculation. In particular, we study the way in which the H2 molecule can interact with graphene sheet through physisorption and chemisorption mechanism. The first mechanism involves the condensation of the hydrogen molecule on the graphene as a result of weak van der Waals forces, while the chemisorption mechanism involves the preliminary dissociation of the H2 molecule and the subsequent reaction of hydrogen atoms with the unsatured C-C bonds to form C-H bonds. To study carefully the possible physisorbed configurations on the graphene sheet, we take in to account van der Waals (vdW) interactions in DFT using the new method (DFT/vdW-WF) recently developed in our group and based on the concept of maximally localized Wannier functions. There are three possible way in which the H2 molecule can adapt to the structure of graphene: the hollow, the bridge and the top site called H, B and T configurations, respectively. We find the hollow site to be most stable physisorbed state with a binding energy of -50 meV. This value, in agreement with experimental results, is also compared with other vdW-correction methods as described in the following paper. Diffusion of the physisorbed configurations on the graphene sheet and activated reaction pathways in which the molecule starts from a physisorbed configuration to end up in a chemisorbed configurations have also been studied.
    Ze względu na możliwość magazynowania wodoru na arkuszu grafenu, badamy nature tego procesu metoda obliczeń ab initio. Cząsteczka H2 może oddziaływać z grafenem na dwa sposoby: fizykosorpcje i chemisorpcje. Mechanizm fizykosorpcji polega na kondensacji cząsteczki wodoru na grafenie na skutek słabych oddziaływań van der Waalsa, podczas gdy mechanizm chemisorpcji polega na wstępnej dysocjacji cząsteczki H2 i następnie reakcji atomów wodoru z niewysyconymi wiązaniami C-C co umożliwia tworzenie wiązań C-H. W celu zobrazowania mechanizmu fizykosorpcji cząsteczek H2 na arkuszu grafenu, analizujemy oddziaływania van der Waalsa (vdW) stosujac teorie funkcjonału gestości (DFT) za pomocą nowej metody (DFT/vdW-WF) niedawno opracowanej w naszej grupie na podstawie koncepcji maksymalnie zlokalizowanych funkcji Wanniera. Analizujemy możliwość absorpcji w różnych miejscach siatki grafenu i orientacje cząsteczki H2 w stosunku do płaszczyzny siatki grafenu. Najbardziej stabilnym miejscem fizykosorbcji jest wnętrze pierścienia grafenu z energia wiązania -50 meV. Wartość ta, zgodna z wynikami doświadczeń, jest także porównywana wartości uzyskanych innymi metodami korekcji vdW. Typowe bariery energetyczne charakteryzujące ścieżkę dyfuzji, są rzędu ∼10 meV. Sytuacja jest inna, gdy cząsteczki wodoru pokonują barierę energetyczna i chemisorbują jako jeden atom wodoru na powierzchni grafenu. Bariery energetyczne w tym przypadku wynoszą około 2-3 eV, w zależności od wybranej ścieżki reakcji.
    Źródło:
    Archives of Metallurgy and Materials; 2012, 57, 4; 1075-1080
    1733-3490
    Pojawia się w:
    Archives of Metallurgy and Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    An atomic scale investigation of the adsorption of sodium oleate on Ca2+ activated quartz surface
    Autorzy:
    Gong, Guichen
    Liu, Jie
    Han, Yuexin
    Zhu, Yimin
    Powiązania:
    https://bibliotekanauki.pl/articles/949736.pdf
    Data publikacji:
    2019
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    quartz
    sodium oleate
    Ca(OH)+
    density functional theory
    Opis:
    In this study, the surface properties and flotation behavior of quartz with NaOl as a collector in the presence of Ca2+ ions were investigated using density functional theory (DFT) calculations in conjunction with flotation tests, adsorption experiments, zeta potential measurements, and solution chemistry calculations. The results of the flotation and adsorption tests proved that Ca2+ promoted the flotation recovery and the adsorption density of sodium oleate on quartz at pH > 8. Zeta potential analyses and solution chemistry calculations demonstrated that Ca(OH)+ was the functional species which activated quartz. DFT calculations indicated that O atoms dominated the quartz (101) surface, and great electrostatic repulsion and space resistance existed between the surface and oleate anion.The spontaneous adsorption of H2O and OH- on the (101) surface made quartz surfaces hydrated and hydroxylated, and resulted in the hydrophilicity of quartz. The adsorption of Ca(OH)+ on quartz (101) surface was more favorable and able to repulse the water film, which decreased the electrostatic repulsion and space resistance, and further facilitated the adsorption of oleate anion. During the activating and collecting adsorption processes, electron transition occurred along the O1—Ca—O2 path, implying Ca(OH)+ acted as an intermediary and electron donator in the activation process.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2019, 55, 2; 426-436
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Simulation of optical spectra of novel Tl4CdI6 and Tl4HgI6 optoelectronic crystals
    Autorzy:
    Franiv, V
    Bovgyra, O
    Kushnir, O
    Franiv, A
    Plucinski, K J
    Powiązania:
    https://bibliotekanauki.pl/articles/173547.pdf
    Data publikacji:
    2014
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    density functional theory
    band structure
    density of states
    optical properties
    Opis:
    The results of calculations using local density approximation and generalized gradient approximation: the total energy depending on the volume of the unit cell, the distribution of the total density of states and the partial contributions of electronic orbitals in the band structure of Tl4CdI6 and Tl4HgI6 crystals are shown in this paper. The spectra of the real part of the dielectric permittivity, the spectra of the imaginary part of permittivity, the reflection spectra and the absorption coefficient of both crystals are obtained using the Kramers–Kronig method. A comparative analysis of theoretical calculations with experimental data is carried out. Substantial influence of electron–phonon broadening is shown.
    Źródło:
    Optica Applicata; 2014, 44, 2; 317-326
    0078-5466
    1899-7015
    Pojawia się w:
    Optica Applicata
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    A Theoretical Study of Polyethylene Glycol Polynitrates as Potential Highly Energetic Plasticizers for Propellants
    Autorzy:
    Wang, Guixiang
    Xu, Yimin
    Zhang, Wenjing
    Gong, Xuedong
    Powiązania:
    https://bibliotekanauki.pl/articles/358877.pdf
    Data publikacji:
    2019
    Wydawca:
    Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego
    Tematy:
    polyethylene glycol polynitrates
    density functional theory
    density
    specific impulse
    stability
    Opis:
    Polyethylene glycol polynitrates may be used as plasticizers in propellants. In this study, ten derivatives of ethylene glycol dinitrate were investigated using the density functional theory method. The fitted densities (ρ’exp.) were obtained and were very close to the experimental values. The detonation properties were predicted using the modified Kamlet-Jacobs equations and the specific impulse (Is) was evaluated according to the largest exothermic principle. A new indicator, K = Is · ρ’exp., is proposed to evaluate the energetic characteristics of the plasticizers. Thermal stability is discussed by calculating the bond dissociation energies or energy barriers. The O−NO2 bond is the trigger bond for all of the compounds studied. Considering the energetic properties and stability, diethylene glycol tetranitrate, triethylene glycol hexanitrate, tetraethylene glycol octanitrate, pentaethylene glycol decanitrate and hexaethylene glycol dodecanitrate are potential energetic plasticizers for solid propellants. The influences of the −O−CH2−CH2− and −O−CH(ONO2)−CH(ONO2)− groups are also discussed, which will be helpful for the design of new highly energetic plasticizers by modifying the structures as required.
    Źródło:
    Central European Journal of Energetic Materials; 2019, 16, 2; 194-215
    1733-7178
    Pojawia się w:
    Central European Journal of Energetic Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    DFT studies on the electronic structures of 4-methoxybenzonitrile dye for Dye-Sensitized Solar Cell
    Autorzy:
    Prakasam, A
    Sakthi, D
    Anbarasan, P.M.
    Powiązania:
    https://bibliotekanauki.pl/articles/412205.pdf
    Data publikacji:
    2013
    Wydawca:
    Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
    Tematy:
    Dye sensitizer
    density functional theory
    electronic structure
    absorption spectrum
    Opis:
    The geometries, electronic structures, polarizabilities and hyperpolarizabilities of organic dye sensitizer 4-methoxybenzonitrile was studied based on ab initio HF and Density Functional Theory (DFT) using the hybrid functional B3LYP. Ultraviolet-visible (UV-Vis) spectrum was investigated by Time Dependent DFT (TDDFT). Features of the electronic absorption spectrum in the visible and near-UV regions were assigned based on TDDFT calculations. The absorption bands are assigned to π→π* transitions. Calculated results suggest that the three excited states with the lowest excited energies in 4-methoxybenzonitrile is due to photoinduced electron transfer processes. The interfacial electron transfer between semiconductor TiO2 electrode and dye sensitizer 4-methoxybenzonitrile, is due to an electron injection process from excited dye to the semiconductor’s conduction band. The role of nitro group in 4-methoxybenzonitrile in geometries, electronic structures, and spectral properties were analyzed.
    Źródło:
    International Letters of Chemistry, Physics and Astronomy; 2013, 7, 1; 8-22
    2299-3843
    Pojawia się w:
    International Letters of Chemistry, Physics and Astronomy
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Under Pressure DFT Investigations on Optical and Electronic Properties of PbZrO₃
    Autorzy:
    Nazir, G.
    Tariq, Saad
    Afaq, A.
    Mahmood, Q.
    Saad, S.
    Mahmood, A.
    Tariq, Samar
    Powiązania:
    https://bibliotekanauki.pl/articles/1030608.pdf
    Data publikacji:
    2018-01
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    density functional theory
    optical properties
    electronic structure
    high pressure
    Opis:
    In this article, density functional theory has been used to investigate the structural and optoelectronic properties of PbZrO₃ (PZO) under pressure from 0 to 350 GPa. In order to achieve ground state structural stability, generalized gradient approximations has been utilized. By studying electronic properties, indirect band-gap nature of PZO appears to change at 15 GPa to direct band-gap. Optical analysis include under pressure responses of real and imaginary parts of dielectric function, optical conductivity, optical absorption coefficient, energy loss function, refractive index, reflectivity and extinction coefficient. Most of the results have been found to be consistent with literature. Study reveals that static dielectric constant and band-gap are in accordance with the Penn model which validates our computed results. Moreover, static dielectric constant and static refractive index directly increases with pressure. Material preserves its positive value of refractive index at all pressures and therefore, it is not a negative index metamaterial. Plasma frequency increases directly with pressure that destabilize the under study material. Our results could be very useful for developing novel optoelectronic devices based on PZO suitable to work under extreme conditions.
    Źródło:
    Acta Physica Polonica A; 2018, 133, 1; 105-113
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Adsorption of lead ion on the hydrated rutile (110) surface: a DFT calculation study
    Autorzy:
    Zou, Heng
    Cao, Qinbo
    Chen, Xiumin
    Liu, Dianwen
    Powiązania:
    https://bibliotekanauki.pl/articles/109829.pdf
    Data publikacji:
    2019
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    rutile
    hydrated surface
    lead ion
    adsorption
    density functional theory
    Opis:
    The adsorption behavior of lead species on the hydrated rutile surface was investigated with inductively coupled plasma mass spectrometry (ICP-MS) measurements and density functional theory (DFT) calculations. ICP-MS experiments suggested that lead species can be readily absorbed by the rutile powder in water at pH 6.5. From the ICP-MS results and the species distribution of Pb2+, it was concluded that Pb2+ was the major lead species adsorbing at the rutile/water interface at the pH of 6.5. DFT calculation results indicated that Pb2+ could adsorb at four different sites on the surface. At each site, water molecules or OH groups were involved in the reaction with Pb2+. The water molecules/OH groups on the rutile surface play an important role during the adsorption of Pb2+ on the hydrated rutile surface.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2019, 55, 4; 951-959
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Binding features of N-hexadecanoylglycine on two terminations of fluorapatite (001) surface and their effect on fluorapatite flotation
    Autorzy:
    Zou, Heng
    Liu, Dianwen
    Cao, Qinbo
    Chen, Xiumin
    Powiązania:
    https://bibliotekanauki.pl/articles/1845208.pdf
    Data publikacji:
    2020
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    fluorapatite
    adsorption
    amino acid-based collector
    density functional theory
    Opis:
    N-hexadecanoylglycine (C16Gly) is a newly synthesized collector, which can be used as an efficient collector for fluorapatite (FA) rather than for dolomite. To extend our knowledge regarding the C16Gly collector, the contact angle method was employed to understand the flotation selectivity of C16Gly in the FA and dolomite system. On the other hand, the possible binding models of C16Gly anion on Ca-rich and PO4-rich terminations of FA (001) surface were investigated with density functional theory calculations to reveal the interaction between the C16Gly and the FA surface. Results showed that C16Gly anion could interact with these two terminations to generate 12 low-energy configurations, including bidentate, tridentate and chelating binding models. The C16Gly anion preferred to adsorb onto the Ca-rich termination, which is caused by the weaker electrostatic repulsion force between the C16Gly anion and the PO4 groups on this termination. The adsorption of C16Gly on these terminations was more stable than that on the dolomite (104) surface, which is one of the reasons for the preferential flotation of FA from dolomite using C16Gly as a collector. These findings provide further insights into the selectivity of C16Gly during the flotation of FA and dolomite.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2020, 56, 5; 949-959
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Effect of surface relaxation of rhodochrosite (104) and substitution of Mn by Ca on the electronic structure of rhodochrosite
    Autorzy:
    Zhang, Jingqi
    Zhang, Qin
    Zhang, Tiebin
    Powiązania:
    https://bibliotekanauki.pl/articles/2146903.pdf
    Data publikacji:
    2022
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    density functional theory
    rhodochrosite
    surface relaxation
    surface electrical property
    Opis:
    To explore the difference between the surface and crystal structure of rhodochrosite, relaxation and reconstruction of the rhodochrosite (104) surface are studied by using Density Functional Theory. The calculation results indicated that the C and O atoms with lower reactivity tend to be enriched on the surface, while the Mn atoms with the highest reactivity moved away from the surface. The band gap width decreased from 1.814 eV to 1.614 eV after the formation of the rhodochrosite (104) surface. The electrons on the rhodochrosite (104) surface are more active than crystal. Ca substitution makes the atomic activity on the (104) surface of rhodochrosite more stable. Ca substitution reduces the ability of the surface of rhodochrosite to absorb external electrons, and the surface electrical properties decrease.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2022, 58, 3; art. no. 145991
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Adsorption of methylamine cations on kaolinite basal surfaces : A DFT study
    Autorzy:
    Chen, Jun
    Min, Fan-fei
    Liu, Ling-yun
    Jia, Fei-fei
    Powiązania:
    https://bibliotekanauki.pl/articles/949692.pdf
    Data publikacji:
    2020
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    kaolinite
    methylamine cations
    density functional theory
    competitive adsorption
    adsorption mechanism
    Opis:
    To explore the interaction of alkylamine surfactants with kaolinite, the density functional theory (DFT) method was used to calculate the single adsorption of different methylamine cation on kaolinite basal surfaces and the competitive adsorption of methylamine cation and water molecule on kaolinite basal surfaces, respectively. Different methylamine cations can adsorb on kaolinite basal surfaces by electrostatic interaction and hydrogen bonds, and the methylamine cations more easily adsorbed on kaolinite Si-O surface. In the case of competitive adsorption with water molecule, the methylamine cation is capable of flushing out the surrounding water molecule to get rid of its steric effect and stably adsorbing on kaolinite basal surfaces, and the adsorption state of the competitive adsorption system is more stable. The adsorption mechanism of methylamine cation on kaolinite basal surface should be the result of electrostatic interaction and hydrogen bonds, and the electrostatic interaction plays the main role.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2020, 56, 2; 338-349
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Decomposition Pathways for Aqueous Hydroxylammonium Nitrate Solutions: a DFT Study
    Autorzy:
    Izato, Y.
    Koshi, M.
    Miyake, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/357968.pdf
    Data publikacji:
    2017
    Wydawca:
    Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego
    Tematy:
    hydroxylamine nitrate
    reaction pathway
    liquid-phase reaction
    density functional theory
    Opis:
    Hydroxylammmonium nitrate (hydroxylamine nitrate, HAN) is one of the most promising candidates as a replacement for commonly used liquid mono-propellants such as hydrazine. The reaction pathways involved in the initial and the catalytic decomposition of HAN in aqueous solution were determined using quantum chemistry calculations incorporating solvent effects. Optimized structures were obtained for the reactants, products and transition states at the ωB97XD/6-311++G(d,p)/SCRF = (solvent = water) level of theory and the total electron energies of these structures were calculated at the CBS-QB3 level of theory. In the initial decomposition, the ion-neutral NH3OH+-HNO3 reaction, the neutral-neutral NH3O-HNO3 reaction and the HNO3 self-decomposition pathways were all found to have reasonable energy barriers, with values of 91.7 kJ/mol, 88.7 kJ/mol and 89.8 kJ/mol, respectively. The overall reaction resulting from any of these pathways can be written as: HAN → HONO + HNO + H2O. The ionic reaction is dominant during the initial decomposition of HAN in aqueous solution because NH3OH+ and NO3– are the major species in such solutions. We also developed six catalytic mechanisms and each of these schemes provided the same global reaction: NH2OH + HONO → N2O + 2H2O. The t-ONONO2 oxidizing scheme is the most plausible based on the energy barrier results.
    Źródło:
    Central European Journal of Energetic Materials; 2017, 14, 4; 888-916
    1733-7178
    Pojawia się w:
    Central European Journal of Energetic Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    A first-principle study of the effect of Fe/Al impurity defects on the surface wettability of dolomite
    Autorzy:
    Chen, Hong
    Ao, Xianquan
    Cao, Yang
    Li, Cuiqin
    Jiang, Chunyan
    Powiązania:
    https://bibliotekanauki.pl/articles/2146916.pdf
    Data publikacji:
    2022
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    density functional theory
    phosphate rock flotation
    dolomite
    surface wettability
    density of states
    Opis:
    The presence of Fe and Al atoms in large quantities in phosphate ores can significantly affect the surface properties of the minerals during flotation. In this study, the effects of Fe/Al impurities on the adsorption of H2O molecules on dolomite, including the density of states (DOS), Mulliken bond group values, and charge groups, were investigated and the adsorption energy was analyzed using density functional theory. The results show that the adsorption of H2O molecules on perfect and Fe/Al-substituted dolomites is weak chemisorption, and the Fe and Al impurities weaken and enhance the adsorption capacity of H2O molecules, respectively. Therefore, the hydrophilicity of the dolomite surface increases in the following order: Fe-substituted dolomite < perfect dolomite < Al-substituted dolomite. The Mulliken charge and bond group analysis shows that the adsorption of H2O molecules on dolomite is primarily through the interaction between Ow and Ca atoms, where the d orbitals of Ca atoms provide charges for Ow atoms to form ionic bonds, which related to the poor electronegativity of Ca atoms and their weak valence electron binding ability. The DOS analysis shows that, during the adsorption of H2O molecules on dolomite, Mg and Al atoms have less influence on the dolomite surface, whereas Fe and Ca atoms undergo competitive adsorption, which inhibits the interaction between Ca atoms and H2O molecules on the dolomite surface.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2022, 58, 4; art. no. 150702
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Potential Energy Surface (PES) scan of gas-phase L-proline
    Autorzy:
    El Guerdaoui, A.
    El Kahoui, Y.
    Bourjila, M.
    Tijar, R.
    El Gridani, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/412094.pdf
    Data publikacji:
    2014
    Wydawca:
    Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
    Tematy:
    ab initio calculations
    L-proline
    density functional theory
    potential energy surface
    Opis:
    We performed here a systematic ab initio calculations on neutral gas-phase L-proline. A total of 8 local minima were located by geometry optimization of the trial structures using density functional theory (DFT) with B3LYP three parameter hybrid potential coupled with the 6-31G)d( basis set. The absolute minimum obtained will be subject to a rigid potential energy surface (PES) scan by rotating its carboxylic group using the same method with more accurate basis set B3LYP/6-311++G(d,p), to get a deeper idea about its conformational stability. The main aim of the present work was the study of the rigidity of the L-proline structure and the puckering of its pyrrolidine ring.
    Źródło:
    International Letters of Chemistry, Physics and Astronomy; 2014, 19, 1; 26-34
    2299-3843
    Pojawia się w:
    International Letters of Chemistry, Physics and Astronomy
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Tuning the Charge Transfer and Optoelectronic Properties of 4,6-Di(Thiophene-2-YL)Pyrimidine via Oligocenothiophene Substitution
    Autorzy:
    Irfan, A.
    Chaudhry, A. R.
    Al-Sehemi, A. G.
    Muhammad, S.
    Jin, R.
    Tang, S.
    Powiązania:
    https://bibliotekanauki.pl/articles/356638.pdf
    Data publikacji:
    2018
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    organic semiconductors
    oligocene
    density functional theory
    optoelectronic properties
    charge transfer properties
    Opis:
    Five new derivatives of 4,6-di(thiophen-2-yl)pyrimidine (DTP) were designed by structural modification with the aim to tune the electro-optical and charge transfer properties. The effect of oligocene and oligocenothiophene incorporation/substitution was investigated on various properties of interests. The smaller hole reorganization energy revealed that compounds 1-5 might be good hole transfer contenders. The smaller hole reorganization energy of newly designed five DTP derivatives than the pentacene showed that prior compounds might be good/comparable hole transfer materials than/to that of pentacene. The computed electron reorganization energy of DTP derivatives 1-5 are 124, 185, 93, 95 and 189 meV smaller than the meridional-tris (8-hydroxyquinoline) aluminum (mer-Alq3) illuminating that electron mobility of these derivatives might be better/comparable than/to referenced compound.
    Źródło:
    Archives of Metallurgy and Materials; 2018, 63, 4; 1629-1636
    1733-3490
    Pojawia się w:
    Archives of Metallurgy and Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Theoretical study of proton-transfer energy surfaces in small water clusters and cubic ice
    Autorzy:
    Czaplewski, C.
    Powiązania:
    https://bibliotekanauki.pl/articles/1954062.pdf
    Data publikacji:
    1998
    Wydawca:
    Politechnika Gdańska
    Tematy:
    proton-transfer energy surface
    small water clusters
    cubic ice
    density functional theory
    Opis:
    The energetics of proton transfer in water clusters consisting of two to six molecules and in cubic ice was analyzed in detail using both Hartree Fock and gradient-corrected density functional theory. Since the energy of the ion-pair structure created by proton transfer is always higher than that of the neutral water structure grid calculations and constrained geometry optimization are needed. In the case of cubic ice various arrangements of the hydrogen atoms on a fixed oxygen lattice were investigated. In this system proton transfer leads to the creation of ionic point defects which are saddle points on the potential energy surface.
    Źródło:
    TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 1998, 2, 1; 31-45
    1428-6394
    Pojawia się w:
    TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
    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:
    First principle analysis of electronic, optical and thermoelectric characteristics of XBiO3 (X = Al, Ga, In) perovskites
    Autorzy:
    Mahmood, Q.
    Rouf, S. A.
    Algrafy, E.
    Murtaza, G.
    Ramay, S. M.
    Mahmood, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/1818225.pdf
    Data publikacji:
    2020
    Wydawca:
    Polska Akademia Nauk. Stowarzyszenie Elektryków Polskich
    Tematy:
    density functional theory
    structural stability
    optoelectronics
    thermoelectric applications
    indirect band gap semiconductors
    Opis:
    The perovskites XBiO3 (X = Al, Ga, In) have been studied in terms of mechanical, optical and thermoelectric behavior for energy harvesting application. Density functional theory is applied to study electronic, optical and thermoelectric properties of the studied materials. Structural, mechanical and thermodynamic stabilities are confirmed from the tolerance factor, Born mechanical stability and formation energy/specific heat capacity. Poisson and Plough ratios show the studied materials are ductile and have ability to withstand pressure. Band structure analysis shows the indirect band gap 3.0/2.1/1.0 eV for ABO/GBO/IBO. A complete set of optical spectra is reported by dielectric constants, refractive index, optical conduction, absorption of light and optical loss energy. Shifting of maximum absorption band to visible region increases the potential of perovskites XBiO3. Transport characteristics are also investigated by electrical conductivity, Seebeck coefficient and figure of merit.
    Źródło:
    Opto-Electronics Review; 2020, 28, 1; 8--14
    1230-3402
    Pojawia się w:
    Opto-Electronics Review
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Detonation Performance of Oxygen-rich Trinitromethylsubstituted Pyrazoles: an in-silico Investigation
    Autorzy:
    Naithani, N.
    George, B. K.
    Powiązania:
    https://bibliotekanauki.pl/articles/358132.pdf
    Data publikacji:
    2018
    Wydawca:
    Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego
    Tematy:
    nitropyrazole
    aminonitropyrazoles
    detonation velocity
    detonation pressure
    density functional theory
    high energy molecules
    Opis:
    A new class of high energy molecules was designed and their detonation properties were evaluated using thermo-chemical parameters obtained from quantum chemical calculations at B3LYP/6-31G(d,p) level. The designed molecules exhibited high density, positive oxygen balance and excellent detonation properties. The impact sensitivity of these molecules, in terms of H50 values, was also evaluated from structural correlations. Among these, 3,4,5-tris(trinitromethyl)1H-pyrazol-1-amine (N13) showed the highest detonation pressure (40.67 GPa) and highest detonation velocity (9.17 km/s), though it exhibited high impact sensitive (H50 = 15 cm). Interestingly, 4,5-dinitro-3-(trinitromethyl)-1H-pyrazol-1-amine (N01) (detonation pressure 39.69 GPa; detonation velocity 9.23 km/s) was found to be an ideal high energy molecule with a near zero oxygen balance. The H50 value of N01 was predicted to be 64 cm, which is higher in magnitude, indicating a lower sensitivity than that of the conventionally used RDX (H50 = 26 cm).
    Źródło:
    Central European Journal of Energetic Materials; 2018, 15, 4; 537-533
    1733-7178
    Pojawia się w:
    Central European Journal of Energetic Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Adsorption of quaternary ammonium salt hydrophobic modifiers on the α-quartz (001) surface: a density functional theory study
    Autorzy:
    Liu, Chunfu
    Wang, Weitao
    Wang, Han
    Zhu, Chenyu
    Ren, Bao
    Powiązania:
    https://bibliotekanauki.pl/articles/24085768.pdf
    Data publikacji:
    2023
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    α-quartz (001) surface
    quaternary ammonium salt
    density functional theory
    adsorption mechanism
    Opis:
    To investigate the adsorption mechanism of quaternary ammonium salt on the α-quartz (001) surface, the adsorption models of hydrophobic modifiers 1231, 1431, 1631 and 1831 were constructed and simulated using the density functional theory (DFT). Results indicate that the adsorption energy of quaternary ammonium salt increases with the increase of carbon chain length, and the adsorption en-ergy reaches the maximum at 18 carbon atoms; however, the adsorption capacity of 1631 is weak owing to the carbon chain deflection. Based on the Mulliken bond population analysis, reagent 1831 has the strongest interaction with α-quartz (001) surface compared with 1231, 1431 and 1631; and during the adsorption process, charge transfer and electrostatic attraction occur between the reagent and α-quartz (001) surface with similar degrees of charge transfer observed. This study emphasizes that electrostatic attraction plays a key role in the adsorption process, while the week hydrogen bonding plays a second-ary role.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2023, 59, 3; art. no. 170260
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    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:
    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:
    Thermal Expansion of Explosive Molecular Crystals: Anisotropy and Molecular Stacking
    Autorzy:
    Qian, W.
    Zhang, C.
    Xiong, Y.
    Zong, H.
    Zhang, W.
    Shu, Y.
    Powiązania:
    https://bibliotekanauki.pl/articles/358262.pdf
    Data publikacji:
    2014
    Wydawca:
    Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego
    Tematy:
    energetic material
    anisotropic thermal expansion
    molecular stacking
    molecular dynamics simulation
    density functional theory method
    Opis:
    Molecular dynamics simulations of three typical explosive crystals, octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX), 1,1-diamino-2,2- dinitroethene (FOX-7) and 1,3,5-triamino-2,4,6-trinitrobenzene (TATB), were carried out under NPT ensemble and selected force field. The equilibrium structures at elevated temperatures were obtained, which show that the stacking behaviour of the molecules does not change with temperature. The coefficient of thermal expansion (CTE) values were calculated by linear fitting methods, and the results show that the CTE values are close to the experimental results and are anisotropic. The total energies of the cells expanding along each single crystallographic axis were calculated by the periodic density functional theory method, indicating that the energy change rates are anisotropic, and correlation equations of the energy change vs. CTE values were established. The essence of the anisotropy of the explosive crystal’s thermal expansion was compared and elucidated.
    Źródło:
    Central European Journal of Energetic Materials; 2014, 11, 1; 59-81
    1733-7178
    Pojawia się w:
    Central European Journal of Energetic Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Synthesis and Theoretical Studies of a New Insensitive Explosive, 2’-Methyl-3-nitro-2’H-[1,3’-bi(1,2,4-triazole)]-5,5’-diamine
    Autorzy:
    Luo, J.
    Liu, Y.
    Wang, J.
    Chai, T.
    Yuan, J.
    Chang, S.
    Yu, Y.
    Jing, S.
    Ma, H.
    Powiązania:
    https://bibliotekanauki.pl/articles/358633.pdf
    Data publikacji:
    2017
    Wydawca:
    Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego
    Tematy:
    insensitive explosive
    synthesis
    theoretical studies
    density functional theory
    new 1,2,4-triazole derivative
    Opis:
    A new insensitive energetic material 2’-methyl-3-nitro-2’H-[1,3’-bi(1,2,4-triazole)]-5,5’-diamine (1) was prepared by a three-step synthesis from commercially available chemicals. The energetic title compound was comprehensively characterized by various means, including FT-IR, multinuclear (1H, 13C, 14N) NMR spectroscopy, elemental analysis, HPLC and thermal analysis. The sensitivities of the synthesized material towards various external stimuli (impact, friction) were determined according to the BAM method. The optimized structure and related thermodynamic parameters were obtained at the DFT-B3LYP/6-31+G** theoretical level. The detonation properties of the material were also predicted according to the Kamlet-Jacobs formulae and the Monte-Carlo method. The results show that the density, heat of formation, detonation velocity, detonation pressure, impact sensitivity and purity were 1.83 g/cm3, 369 kJ/mol, 7.52 km/s, 25.4 GPa, 82.3 J and 97.7%, respectively. In addition, the compound was an insensitive high explosive which could meet the requirements of high energetic materials.
    Źródło:
    Central European Journal of Energetic Materials; 2017, 14, 2; 269-280
    1733-7178
    Pojawia się w:
    Central European Journal of Energetic Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Badania strukturalne cyklicznych β-aminoketonów z wykorzystaniem metod obliczeniowych i analizy NMR
    Structural studies of cyclic β-amino ketons using computational and NMR methods
    Autorzy:
    Sidorowicz, K.
    Łaźny, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/142626.pdf
    Data publikacji:
    2015
    Wydawca:
    Stowarzyszenie Inżynierów i Techników Przemysłu Chemicznego. Zakład Wydawniczy CHEMPRESS-SITPChem
    Tematy:
    alkaloidy
    konformacje
    teoria funkcjonału gęstości
    spektroskopia NMR
    alkaloids
    conformations
    density functional theory
    NMR spectroscopy
    Opis:
    Przestrzenna konfiguracja na atomie azotu w cyklicznych β-aminoketonach powoduje, że związki te mogą występować w dwóch stereoizomerycznych formach, w których podstawniki na tym atomie mogą przyjmować orientację aksjalną lub ekwatorialną w stosunku do pierścienia piperydonu. Stereochemia N-podstawionych bicyklicznych β-aminoketonów była badana za pomocą metod eksperymentalnych i teoretycznych, m.in.: spektroskopia NMR, spektroskopii mikrofalowa, rentgenografii strukturalnej i obliczeń DFT.
    Because of pyramidal configuration of the nitrogen atom, tropanes, granatanes, and their derivatives can exist in two stereoisomeric forms, in which N-substituents can be oriented axial or equatorial with respect to the piperidone ring. The N-invertomer stereochemistry of N-substituted bicyclic β-amino ketones has been investigated using experimental, and theoretical methods, such as NMR, microwave spectroscopy, crystallography, and DFT calculations.
    Źródło:
    Chemik; 2015, 69, 7; 401-410
    0009-2886
    Pojawia się w:
    Chemik
    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:
    DFT/PM3 study of the enoyl-CoA hydratase catalyzed reaction
    Autorzy:
    Pawlak, J.
    Bahnson, B.
    Anderson, V.
    Powiązania:
    https://bibliotekanauki.pl/articles/146962.pdf
    Data publikacji:
    2002
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    coenzyme-A
    density functional theory
    enoyl-CoA hydratase
    kinetic isotope effect
    ONIOM model
    stepwise mechanism
    thiolester enolate
    Opis:
    The enoyl-CoA hydratase catalyzed hydration of alfa,beta-unsaturated thiolesters has been modeled by using the crystal structure of 4-(N,N-dimethylamino)cinnamoyl-CoA bound at the active site. The quantum chemical calculation used the ONIOM mixed level procedure to permit the substrate thiolester and water molecule to be modeled using B3LYP/6-31G(d) level of theory and the active site residues modeled at a semiempirical level using the PM3 Hamiltonian. The results permitted the identification of a stable thiolester enolate intermediate, supporting a stepwise reaction mechanism. The calculation also suggests that the same proton removed from the nucleophilic water molecule is transferred to C alfa in the subsequent protonation of the enolate intermediate. This observation reconciles the stepwise mechanism with the previously reported double isotope effect study [3].
    Źródło:
    Nukleonika; 2002, 47,suppl.1; 33-36
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Density Functional Theory Study Of The Interaction Of Hydroxyl Groups With Iron Surface
    Badanie wzajemnego oddziaływania grup hydroksylowych na powierzchni żelaza za pomocą teorii funkcjonału gęstości
    Autorzy:
    Nunomura, N.
    Sunada, S.
    Powiązania:
    https://bibliotekanauki.pl/articles/355298.pdf
    Data publikacji:
    2015
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    density functional theory
    hydroxyl groups
    iron surface
    adsorption energy
    teoria funkcjonału gęstości
    grupy hydroksylowe
    powierzchnia żelaza
    energia adsorpcji
    Opis:
    The electronic interaction of hydroxyl groups with Fe(100) surface is modelled using a density functional theory (DFT) approach. The adsorption energies and structures of possible adsorption sites are calculated. According to our calculations of the adsorption energies, the interaction between oxygen atom of OH species and surface iron atom is shown to be strong. It is likely to be due to the interaction of the lone-pair electrons of oxygen and the 3d orbital electrons of iron atom. At low coverage (0.25ML), the most favorable adsorption sites are found to be two-fold bridge sites, and the orientation of the O-H bond is tilted to the surface normal. Further, the adsorption energy is found to be decreasing with the increasing OH group coverage.
    Wzajemne oddziaływanie elektronowe grup hydroksylowych na powierzchni Fe(100) modelowano stosując metodę teorii funkcjonału gęstości (ang. density functional theory; DFT). Dokonano obliczeń energii adsorpcji oraz struktury potencjalnych centrów adsorpcji. Na podstawie otrzymanych wyników stwierdzono, że pomiędzy atomem tlenu grupy OH, a powierzchnią atomu żelaza występuje silne oddziaływanie. Jest to prawdopodobnie spowodowane oddziaływaniem wolnej pary elektronowej tlenu z elektronami atomu żelaza na orbitalach 3d. Przy niskim poziomie pokrycia (0,25 ML), najbardziej uprzywilejowane centra aktywne stanowią podwójne pozycje mostkowe, a orientacja wiązania O-H jest prostopadła do powierzchni. Ponadto energia adsorpcji zmniejsza się wraz ze wzrostem ilości grup OH na powierzchni.
    Źródło:
    Archives of Metallurgy and Materials; 2015, 60, 2A; 931-933
    1733-3490
    Pojawia się w:
    Archives of Metallurgy and Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Właściwości czasowo-rozdzielcze słabych międzycząsteczkowych wiązań wodorowych C-H···F
    Time-resolved properties of intermolecular C-H···F hydrogen bonds
    Autorzy:
    Polańska, Marta
    Rodziewicz, Paweł
    Powiązania:
    https://bibliotekanauki.pl/articles/27310029.pdf
    Data publikacji:
    2023
    Wydawca:
    Polskie Towarzystwo Chemiczne
    Tematy:
    wiązanie wodorowe
    teoria funkcjonału gęstości
    dynamika molekularna Cara i Parrinello
    hydrogen bond
    density functional theory
    Car-Parrinello molecular dynamics
    Opis:
    The hydrogen bond is one of the most important and interesting phenomena in nature. In this publication we will shed light on the discovery of hydrogen bond and a time evolution of its definition in the last 100 years. Both structural and spectroscopic parameters of the hydrogen bond will be discussed. A special focus will be given to the latest IUPAC definition of the hydrogen bond and its consequences to scientific research. The main aim of this study is to highlight theoretical studies based on first principles calculations and molecular dynamics simulations which not only support experimental results but also provide parameters which are crucial to understand the nature of hydrogen bonds. Particular attention will be given to methods and theoretical ideas used in the computational studies of hydrogen bonds. Utilizing static DFT/ab initio calculations and molecular dynamics simulations enables comparison of different binding energies and studying time evolution of the hydrogen-bonded molecular system on the atomistic level. We will discuss time-resolved properties of weak intermolecular hydrogen bonds, using as an example C-H···F containing model systems, namely F3CH*(HF)n molecular complexes and (F3CH)2-4 aggregates.
    Źródło:
    Wiadomości Chemiczne; 2023, 77, 9-10; 899--919
    0043-5104
    2300-0295
    Pojawia się w:
    Wiadomości Chemiczne
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Density functional theory based modeling of the corrosion on iron surfaces
    Modelowanie korozji na powierzchni żelaza w oparciu o teorię funkcjonału gęstości
    Autorzy:
    Nunomura, N.
    Sunada, S.
    Powiązania:
    https://bibliotekanauki.pl/articles/351628.pdf
    Data publikacji:
    2013
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    density functional theory
    aqueous corrosion
    iron surface
    water molecules
    oxygen
    teoria funkcjonału gęstości
    korozja wodna
    powierzchnia żelaza
    cząsteczki wody
    tlen
    Opis:
    In order to understand the first steps of the aqueous corrosion of iron, we have performed density functional theory (DFT) based calculations for water molecules and pre-covered oxygen on iron surface. The surface structure is modeled by iron atomic layer and vacuum region, and then oxygen atom and water molecules are displaced on the surface. Self consistent DFT calculations were performed using a numerical atomic orbital basis set and a norm-conserve pseudopotential method. According to our calculations, with increasing surface oxygen coverage, the iron surface is found to be not activated, which leads to a feeble adsorption of water molecules on iron surface. Our results show that the surface covered oxygen exerts an influence on the adsorption of water molecules on iron surface.
    W celu zrozumienia początkowych etapów korozji żelaza w środowisku wodnym wykonaliśmy obliczenia dla cząsteczek wody i powierzchni żelaza pokrytej tlenem przy użyciu teorii funkcjonału gęstości (DFT). Model struktury powierzchni zawiera warstwę atomów żelaza i obszar próżni, a następnie atomy tlenu i cząsteczki wody rozmieszczane na powierzchni. Obliczenia DFT wykonano w zastosowaniem bazy orbitali atomowych i metody pseudopotencjału zachowania normy (norm-conserve). Zgodnie z wynikami naszych obliczeń, ze wzrostem pokrycia powierzchni przez tlen, powierzchnia żelaza nie jest aktywowana, co prowadzi do słabej adsorpcji cząsteczek wody na powierzchni żelaza. Nasze wyniki wskazują, ze powierzchnia pokryta tlenem wywiera wpływ na adsorpcje cząsteczek wody na powierzchni żelaza.
    Źródło:
    Archives of Metallurgy and Materials; 2013, 58, 2; 321-323
    1733-3490
    Pojawia się w:
    Archives of Metallurgy and Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Effect of Acid Modification on Porous Structure and Adsorption Properties of Different Type Ukrainian Clays for Water Purification Technologies
    Autorzy:
    Budash, Yrii
    Plavan, Viktoriia
    Tarasenko, Nataliia
    Ishchenko, Olena
    Koliada, Maksym
    Powiązania:
    https://bibliotekanauki.pl/articles/24201684.pdf
    Data publikacji:
    2023
    Wydawca:
    Polskie Towarzystwo Inżynierii Ekologicznej
    Tematy:
    montmorillonite
    palygorskite
    acid modification
    acid-activated clay
    sorption capacity
    water purification technology
    Brunauer-Emmette-Teller method
    density functional theory method
    Opis:
    Clay minerals, as adsorbents, are widely available, have large specific surface area, and the ability for cation exchange, which makes them applicable in wastewater treatment from heavy metal ions. This study investigated the effect of acid modification on the porous structure and adsorption properties of montmorillonite (MMT) and palygorskite (PAL) clays of the Cherkasy deposit (Ukraine). Acid modification of clay samples was carried out with chloride acid after preliminary refining. Clay particles were analyzed using optical polarization microscopy with recording of digital images of the study. The area and perimeter of individual particles of clay samples were determined. The equivalent diameter and shape factor were calculated. The porosity characteristics of the samples were determined. Pore surface area was calculated by the Brunauer-Emmette-Teller (BET) method. Total volume, mean diameters, and pore size distribution were obtained using the Density Functional Theory (BFT) method. Acid modification improved the porous structure of clay samples. BET surface area of the pores of the initial sample of palygorskite clay is significantly higher compared to the montmorillonite type clay (140.66 and 83.61 m2/g, respectively). Acid modification of the PAL sample contributes to an increase in the BET surface area by approximately 1.7 times. Acid modification increases the surface area and total pore volume by approximately 2.3 times for MMT samples and 1.76 times for PAL samples. Dimensional characteristics of the pores of the MMT sample were to shift after activation, while for the PAL sample, their average size increases sharply by approximately 3.2 times. This suggested the additional formation of pores in the interfibrillar regions of the PAL sample during its acid activation. The effect of acid modification on the sorption capacity was investigated by means of methylene blue exhaustion. Sorption efficiency increases by 6-14%, compared to unmodified samples and is determined by the contact time and the type of clay. Increasing the contact time from 24 to 72 hours leads to an increase in the sorption efficiency of activated MMT and PAL samples by 36 and 30%, respectively. Acid-activated clay minerals, in particular montmorillonite, can be used as part of sorption elements to increase the efficiency of wastewater treatment technologies from heavy metal ions.
    Źródło:
    Journal of Ecological Engineering; 2023, 24, 5; 210--221
    2299-8993
    Pojawia się w:
    Journal of Ecological Engineering
    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 1-44 z 44

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