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排序方式: 共有199条查询结果,搜索用时 15 毫秒
1.
Dzhimak S. S. Kopytov G. F. Tumaev E. N. Isaev V. A. Moiseev A. V. Malyshko V. V. Elkina A. A. Baryshev M. G. 《Russian Physics Journal》2021,63(11):1922-1931
Russian Physics Journal - Based on the classical quantum-mechanical approach, the physical mechanism of isotope fractionation is proposed associated with the predominance of a certain number of... 相似文献
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Yoichi Makimizu Nhat Truong Nguyen Jiri Tucek Hyo-Jin Ahn JeongEun Yoo Mahshid Poornajar Imgon Hwang Stepan Kment Prof. Dr. Patrik Schmuki 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(12):2685-2692
Photoelectrochemical (PEC) water splitting is a promising method for the conversion of solar energy into chemical energy stored in the form of hydrogen. Nanostructured hematite (α-Fe2O3) is one of the most attractive materials for a highly efficient charge carrier generation and collection due to its large specific surface area and the short minority carrier diffusion length. In the present work, the PEC water splitting performance of nanostructured α-Fe2O3 is investigated which was prepared by anodization followed by annealing in a low oxygen ambient (0.03 % O2 in Ar). It was found that low oxygen annealing can activate a significant PEC response of α-Fe2O3 even at a low temperature of 400 °C and provide an excellent PEC performance compared with classic air annealing. The photocurrent of the α-Fe2O3 annealed in the low oxygen at 1.5 V vs. RHE results as 0.5 mA cm−2, being 20 times higher than that of annealing in air. The obtained results show that the α-Fe2O3 annealed in low oxygen contains beneficial defects and promotes the transport of holes; it can be attributed to the improvement of conductivity due to the introduction of suitable oxygen vacancies in the α-Fe2O3. Additionally, we demonstrate the photocurrent of α-Fe2O3 annealed in low oxygen ambient can be further enhanced by Zn-Co LDH, which is a co-catalyst of oxygen evolution reaction. This indicates low oxygen annealing generates a promising method to obtain an excellent PEC water splitting performance from α-Fe2O3 photoanodes. 相似文献
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Stanislav Kozin Vladimir Skrebitsky Rodion Kondratenko Alexander Kravtsov Elena Butina Arkady Moiseev Vadim Malyshko Mikhail Baryshev Anna Elkina Stepan Dzhimak 《Molecules (Basel, Switzerland)》2021,26(7)
The deuterium content modification in an organism has a neuroprotective effect during the hypoxia model, affecting anxiety, memory and stress resistance. The aim of this work was to elucidate the possible mechanisms of the medium D/H composition modification on nerve cells. We studied the effect of an incubation medium with a 50 ppm deuterium content compared to a medium with 150 ppm on: (1) the activity of Wistar rats’ hippocampus CA1 field neurons, (2) the level of cultured cerebellar neuron death during glucose deprivation and temperature stress, (3) mitochondrial membrane potential (MMP) and the generation of reactive oxygen species in cultures of cerebellar neurons. The results of the analysis showed that the incubation of hippocampal sections in a medium with a 50 ppm deuterium reduced the amplitude of the pop-spike. The restoration of neuron activity was observed when sections were returned to the incubation medium with a 150 ppm deuterium content. An environment with a 50 ppm deuterium did not significantly affect the level of reactive oxygen species in neuron cultures, while MMP decreased by 16–20%. In experiments with glucose deprivation and temperature stress, the medium with 50 ppm increased the death of neurons. Thus, a short exposure of nerve cells in the medium with 50 ppm deuterium acts as an additional stressful factor, which is possibly associated with the violation of the cell energy balance. The decrease in the mitochondrial membrane potential, which is known to be associated with ATP synthesis, indicates that this effect may be associated with the cell energy imbalance. The decrease in the activity of the CA1 field hippocampal neurons may reflect reversible adaptive changes in the operation of fast-reacting ion channels. 相似文献
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Structure of Framework Aluminum Lewis Sites and Perturbed Aluminum Atoms in Zeolites as Determined by 27Al{1H} REDOR (3Q) MAS NMR Spectroscopy and DFT/Molecular Mechanics 下载免费PDF全文
Dr. Jiří Brus Libor Kobera Dr. Wolfgang Schoefberger Dr. Martina Urbanová Petr Klein Dr. Petr Sazama Dr. Edyta Tabor Dr. Stepan Sklenak Dr. Anna V. Fishchuk Dr. Jiří Dědeček 《Angewandte Chemie (International ed. in English)》2015,54(2):541-545
Zeolites are highly important heterogeneous catalysts. Besides Brønsted SiOHAl acid sites, also framework AlFR Lewis acid sites are often found in their H‐forms. The formation of AlFR Lewis sites in zeolites is a key issue regarding their selectivity in acid‐catalyzed reactions. The local structures of AlFR Lewis sites in dehydrated zeolites and their precursors—“perturbed” AlFR atoms in hydrated zeolites—were studied by high‐resolution MAS NMR and FTIR spectroscopy and DFT/MM calculations. Perturbed framework Al atoms correspond to (SiO)3AlOH groups and are characterized by a broad 27Al NMR resonance (δi=59–62 ppm, CQ=5 MHz, and η=0.3–0.4) with a shoulder at 40 ppm in the 27Al MAS NMR spectrum. Dehydroxylation of (SiO)3AlOH occurs at mild temperatures and leads to the formation of AlFR Lewis sites tricoordinated to the zeolite framework. Al atoms of these (SiO)3Al Lewis sites exhibit an extremely broad 27Al NMR resonance (δi≈67 ppm, CQ≈20 MHz, and η≈0.1). 相似文献
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Petr Kluson Stepan Kment Magdalena Morozova Pavel Dytrych Stanislav Hejda Morwenna Slater Zdenek Hubicka Josef Krysa 《Chemical Papers》2012,66(5):446-460
Chemistry and physics of thin semiconducting layers of various types are subjects of intense research. Especially when nanotechnology
methods such as self-assembly are involved, amazing structural and/or functional properties may appear. Also modern physical
methods using variously organized plasma arrangements are able to produce uniform structures with distinctive functionality.
In this review, based virtually on our own work, discussions on the preparation, structure, morphology, and function of titanium(IV)
oxide nanoscopic thin films are presented. It was shown that structurally and functionally similar titanium(IV) oxide films
can be prepared via completely different preparation techniques. Function tests were arranged as “primary”, covering the assessment
of the light induced charge separation efficiency, and “secondary”, based on photocatalytic surface oxidations. 相似文献
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The structure of liquid indium in a wide temperature range has been investigated by means of X-ray diffraction and reverse Monte Carlo methods. Analysis of temperature dependence of the interatomic distances and coordination numbers allowed us to determine the existence of structural transformation in a liquid state. Moreover, it was found that at a temperature of 640 K thermal expansion coefficients, estimated from temperature dependence of interatomic distances, change its sign from negative to positive confirming the transformations in structure of liquid indium which are observed by temperature variations. 相似文献
10.
Dmitri O. Charkin Stanislav I. Bezzubov Oleg I. Siidra Artem S. Borisov Stepan N. Kalmykov 《无机化学与普通化学杂志》2020,646(11-12):540-543
Crystals of a new uranyl sulfate (C2N4H8S2)[UO2(SO4)2] · 0.3H2O ( 1 ) templated by a relatively rare bis-isothiouronium cation, were formed upon evaporation of aqueous solutions containing uranyl acetate, thiourea, and excess sulfuric acid. The new compound is orthorhombic, P212121, a = 6.928(2) Å, b = 13.398(3) Å, c = 15.225(3) Å, Z = 2. Its crystal structure is comprised of [UO2(SO4)2] moieties linked by hydrogen bonds formed between the template cations and terminal oxygen atoms of the sulfate tetrahedra. The C2N4H8S22+ template is most likely formed in situ during a redox reaction between uranyl cation and thiourea in a strongly acidic medium, with UO22+ partially reduced to U4+. 相似文献