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101.
102.
N. E. Sluchanko A. V. Bogach V. V. Glushkov S. V. Demishev V. Yu. Ivanov M. I. Ignatov A. V. Kuznetsov N. A. Samarin A. V. Semeno N. Yu. Shitsevalova 《Journal of Experimental and Theoretical Physics》2007,104(1):120-138
Precision measurements of transport and magnetic parameters of high-quality CeB6 single crystals are performed in the temperature range 1.8—300 K. It is shown that their resistivity in the temperature interval 5 K < T < T* ≈ 80 K obeys not a logarithmic law, which is typical of the Kondo mechanism of charge carrier scattering, but the law ρ ∝ T ?1/η corresponding to the weak localization regime with a critical index 1/η = 0.39 ± 0.02. Instead of the Curie-Weiss dependences, the asymptotic form χ(T) ∝ T ?0.8 is obtained for magnetic susceptibility of CeB6 in a temperature range of 15–300 K. Analysis of the field dependences of magnetization, magnetoresistance, and the Hall coefficient in the paramagnetic and magnetically ordered phases of CeB6 and comparison with the results of measurements of Seebeck coefficient, the inelastic neutron scattering coefficient, and EPR spectroscopy lead to the conclusion that the Kondo lattice model and skew scattering model cannot be used for describing the transport and thermodynamic parameters of this compound with strong electron correlations. On the basis of detailed analysis of experimental data, an alternative approach to interpreting the properties of CeB6 is proposed using (1) the assumption concerning itinerant paramagnetism and substantial renormalization of the density of electron states upon cooling in the vicinity of the Fermi energy, which is associated with the formation of heavy fermions (spin-polaron states) in the metallic CeB6 matrix in the vicinity of Ce sites; (2) the formation of ferromagnetic nanosize regions from spin polarons at 3.3 K < T < 7 K and a transition to a state with a spin density wave (SDW) at T Q ≈ 3.3 K; and (3) realization of a complex magnetic phase H-T diagram of CeB6, which is associated with an increase in the SDW amplitude and competition between the SDW and antiferromagnetism of localized magnetic moments of cerium ions. 相似文献
103.
Sergei Kotelnikov Andrey Alekseenko Cong Liu Mikhail Ignatov Dzmitry Padhorny Emiliano Brini Mark Lukin Evangelos Coutsias Ken A. Dill Dima Kozakov 《Journal of computer-aided molecular design》2020,34(2):179-189
We describe a new template-based method for docking flexible ligands such as macrocycles to proteins. It combines Monte-Carlo energy minimization on the manifold, a fast manifold search method, with BRIKARD for complex flexible ligand searching, and with the MELD accelerator of Replica-Exchange Molecular Dynamics simulations for atomistic degrees of freedom. Here we test the method in the Drug Design Data Resource blind Grand Challenge competition. This method was among the best performers in the competition, giving sub-angstrom prediction quality for the majority of the targets. 相似文献
104.
Yu. L. Kuznetsova A. V. Nyuchev N. A. Lenshina M. A. Lopatin S. K. Ignatov S. A. Chesnokov M. P. Shurygina A. S. Vavilova A. Yu. Fedorov 《Russian Chemical Bulletin》2018,67(9):1671-1678
Polymerization of methyl methacrylate in bulk in the presence of 4-ethynylcoumarin and 4-butadiynylcoumarin (AIBN, 60 °C) leads to the formation of fluorescent polymers. A hypsochromic shift of fluorescence band maxima of polymer solutions is observed in dichloromethane. It was suggested using the quantum chemical calculations that 4-ethynylcoumarin is attached to the macroradical via the terminal carbon atom of the ethynyl group. The samples of fluorescent organic glasses were prepared. It was established that the addition of coumarins do not influence the microhardness of organic glass. 相似文献
105.
Chaudhuri S Graetz J Ignatov A Reilly JJ Muckerman JT 《Journal of the American Chemical Society》2006,128(35):11404-11415
We report the results of an experimental and theoretical study of hydrogen storage in sodium alanate (NaAlH(4)). Reversible hydrogen storage in this material is dependent on the presence of 2-4% Ti dopant. Our combined study shows that the role of Ti may be linked entirely to Ti-containing active catalytic sites in the metallic Al phase present in the dehydrogenated NaAlH(4). The EXAFS data presented here show that dehydrogenated samples contain a highly disordered distribution of Ti-Al distances with no long-range order beyond the second coordination sphere. We have used density functional theory techniques to calculate the chemical potential of possible Ti arrangements on an Al(001) surface for Ti coverages ranging from 0.125 to 0.5 monolayer (ML) and have identified those that can chemisorb molecular hydrogen via spontaneous or only moderately activated pathways. The chemisorption process exhibits a characteristic nodal symmetry property for the low-barrier sites: the incipient doped surface-H(2) adduct's highest occupied molecular orbital (HOMO) incorporates the sigma antibonding molecular orbital of hydrogen, allowing the transfer of charge density from the surface to dissociate the molecular hydrogen. This work also proposes a plausible mechanism for the transport of an aluminum hydride species back into the NaH lattice that is supported by Car-Parrinello molecular dynamics (CPMD) simulations of the stability and mobility of aluminum clusters (alanes) on Al(001). As an experimental validation of the proposed role of titanium and the subsequent diffusion of alanes, we demonstrate experimentally that AlH(3) reacts with NaH to form NaAlH(4) without any requirement of a catalyst or hydrogen overpressure. 相似文献
106.
V. E. Shebalin A. V. Anisenkov V. M. Aulchenko N. S. Bashtovoy D. A. Epifanov L. B. Epshteyn A. A. Grebenuk F. V. Ignatov A. L. Erofeev O. A. Kovalenko A. N. Kozyrev A. S. Kuzmin I. B. Logashenko K. Yu. Mikhailov G. P. Razuvaev A. A. Ruban B. A. Shwartz A. A. Talyshev V. M. Titov Yu. V. Yudin 《Physics of Atomic Nuclei》2015,78(13):1544-1551
The structure of the barrel calorimeter of the CMD-3 detector is presented in this work. The procedure of energy calibration of the calorimeter and the method of photon energy restoration are described. The distinctive feature of this barrel calorimeter is its combined structure; it is composed of two coaxial subsystems: a liquid xenon calorimeter and a crystalline CsI calorimeter. The calorimeter spatial resolution of the photon conversion point is about 2 mm, which corresponds to an angular resolution of ~6 mrad. The energy resolution of the calorimeter is about 8% for photons with energy of 200 MeV and 4% for photons with energy of 1 GeV. 相似文献
107.
A. S. Antsyshkina G. G. Sadikov V. G. Sevastyanov V. S. Popov P. A. Ignatov A. V. Churakov E. P. Simonenko N. T. Kuznetsov V. S. Sergienko 《Russian Journal of Inorganic Chemistry》2011,56(4):530-538
Tin coordination compounds [Sn(H2O)2Cl4] · 18C6 (I) and [Sn(H2O)2Cl4] · 18C6 · 2H2O (II) were synthesized and identified by IR spectroscopy, CH analysis, and X-ray powder diffraction. The crystal structures of
compounds I and II were determined. The crystals of I and II are orthorhombic; a = 16.871(1) ?, b = 7.7305(7) ?, c = 16.939(1) ?, Z = 4, space group Cmca for I; a = 14.206(2) ?, b = 20.376(3) ?, c = 8.319(1) A, Z = 4, space group Pna21 for II. The structural units of I and II are [Sn(H2O)2Cl4] · 18C6 complex molecules (in II, also water molecules of crystallization). The coordinated water molecules in I are trans and those in II are cis to each other. The structural units in the crystals of I and II are combined only by hydrogen bonds between water molecules and the crown-ether oxygen atoms with the formation of the chain
structure. Complex I was tested as the precursor of tin dioxide in a chemical vapor deposition (CVD) process. The morphology of the obtained film
was studied by atomic force microscopy (AFM) and scanning electron microscopy (SEM), and the composition was studied by laser
mass spectrometry for elemental analysis. 相似文献
108.
S. V. Panteleev S. V. Maslennikov I. V. Spirina S. K. Ignatov M. A. Isakov 《Russian Journal of General Chemistry》2013,83(6):1013-1020
The evolution of the compact copper surface at the etching in the system of CCl4-DMF with a concentration of carbon tetrachloride ≈ 1 M was studied using atomic force microscopy (AFM). The dependence of the copper etch in a rate on the time and the concentration of the oxidizing agent (carbon tetrachloride) was measured. The dynamics of formation and destruction of active centers in the reaction was investigated. 相似文献
109.
M. I. Ignatov V. V. Glushkov S. V. Demishev N. Yu. Shitsevalova A. V. Levchenko E. I. Khayrullin N. E. Sluchanko 《Journal of Experimental and Theoretical Physics》2007,105(1):55-57
Detailed measurements of the Seebeck coefficient S(T) in a broad range of temperatures (T = 2–300 K) have been performed for the first time for RB12 dodecaborides (R = Ho, Er, Tm, Lu) in paramagnetic (diamagnetic for LuB12) and antiferromagnetic states. At intermediate temperatures (10–300 K), the thermopower is determined by the interaction of carriers with phonon modes, which are related to the oscillations of rare-earth atoms in the framework of atomic clusters B12. A comparative analysis of the parameters determining photon drag the thermopower related to the phonon drag and the results of galvanomagnetic measurements shows evidence for a significant effect of spin fluctuations on the behavior of charge transport characteristics in RB12 compounds with strong electron correlations. 相似文献
110.
Yu. P. Fedonenko E. N. Sigida S. A. Konnova V. V. Ignatov 《Russian Chemical Bulletin》2015,64(5):1024-1031
The review presents a discussion of the published data of 2002 to 2014 dealing with structural studies of O-specific polysaccharides, representatives of the Azospirillum diazotrophic rhizobacteria, summarizing the results of a series of authors´ studies. Some general structures incorporated in O-specific polysaccharides responsible for classification of bacterial cultures into serogroups on the basis of immunochemical studies were characterized. The structures of O-specific polysaccharides of seven azospirillum strains identical to those of previously studied strains are presented in this review for the first time. 相似文献