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1.
Liquid-vapor equilibria and azeotropy in isobutanol-n-butanol-butyl butenyl ether ternary system and in isobutanol-butyl butenyl ether and n-butanol-butyl butenyl ether binary systems were studied experimentally and calculated, as well as azeotropy in butyl alcohols-butyl butenyl ether-water systems under atmospheric and reduced pressure. Recovery of commercial butyl alcohols by distillation of alcohol-ether fractions was studied. 相似文献
2.
The formation of a molybdenum reflecting coating with a columnar nanocrystalline structure is studied under the condition when molybdenum is deposited by dc magnetron sputtering on single-crystalline molybdenum mirrors (substrates). The coating is found to peel off together with a polishing-induced imperfect amorphous surface layer of the substrate. This effect aids in obtaining a free mirror-like molybdenum foil. When the amorphous imperfect layer is removed from the substrate before deposition, the reflecting mirror coating has a good adhesion to the substrate. 相似文献
3.
A. V.?Nemukhin B. L.?Grigorenko A. V.?Rogov I. A.?TopolEmail author S. K.?Burt 《Theoretical chemistry accounts》2004,111(1):36-48
A complete cycle of chemical transformations for the serine protease prototype reaction is modeled following calculations with the flexible effective fragment quantum mechanical/molecular mechanical (QM/MM) method. The initial molecular model is based on the crystal structure of the trypsin–bovine pancreatic trypsin inhibitor complex including all atoms of the enzyme within approximately 15–18 Å of the oxygen center O of the catalytic serine residue. Several selections of the QM/MM partitioning are considered. Fractions of the side chains of the residues from the catalytic triad (serine, histidine and aspartic acid) and a central part of a model substrate around the C–N bond to be cleaved are included into the QM subsystem. The remaining part, or the MM subsystem, is represented by flexible chains of small effective fragments, whose potentials explicitly contribute to the Hamiltonian of the QM part, but the corresponding fragment–fragment interactions are described by the MM force fields. The QM/MM boundaries are extended over the C–C bonds of the peptides assigned to the QM subsystem in the enzyme, C–C and C–N bonds in model substrates. Multiple geometry optimizations have been performed by using the RHF/6-31G method in the QM part and OPLSAA or AMBER sets of MM parameters, resulting in a series of stationary points on the complex potential-energy surfaces. All structures generally accepted for the serine protease catalytic cycle have been located. Energies at the stationary points found have been recomputed at the MP2/6-31+G* level for the QM part in the protein environment. Structural changes along the reaction path are analyzed with special attention to hydrogen-bonding networks. In the case of a model substrate selected as a short peptide CH3(NHCO-CH2)2 – HN–CO–(CH2–NHCO)CH3 the computed energy profile for the acylation step shows too high activation energy barriers. The energetics of this rate-limiting step is considerably improved, if more realistic model for the substrate is considered, following the motifs of the ThrI11–GlyI12–ProI13-–CysI14–LysI15–AlaI16–ArgI17–IleI18–IleI19 sequence of the bovine pancreatic trypsin inhibitor. 相似文献
4.
Luzgin MV Stepanov AG Arzumanov SS Rogov VA Parmon VN Wang W Hunger M Freude D 《Chemistry (Weinheim an der Bergstrasse, Germany)》2005,12(2):457-465
By using 13C MAS NMR spectroscopy (MAS = magic angle spinning), the conversion of selectively 13C-labeled n-butane on zeolite H-ZSM-5 at 430-470 K has been demonstrated to proceed through two pathways: 1) scrambling of the selective 13C-label in the n-butane molecule, and 2) oligomerization-cracking and conjunct polymerization. The latter processes (2) produce isobutane and propane simultaneously with alkyl-substituted cyclopentenyl cations and condensed aromatic compounds. In situ 13C MAS NMR and complementary ex situ GC-MS data provided evidence for a monomolecular mechanism of the 13C-label scrambling, whereas both isobutane and propane are formed through intermolecular pathways. According to 13C MAS NMR kinetic measurements, both pathways proceed with nearly the same activation energies (E(a) = 75 kJ mol(-1) for the scrambling and 71 kJ mol(-1) for isobutane and propane formation). This can be rationalized by considering the intermolecular hydride transfer between a primarily initiated carbenium ion and n-butane as being the rate-determining stage of the n-butane conversion on zeolite H-ZSM-5. 相似文献
5.
Tatiana Kuznetsova Vladislav Sadykov Lubsan Batuev Ella Moroz Elena Burgina Vladimir Rogov Vladimir Kriventsov Dmitrii Kochubey 《天然气化学杂志》2006,15(3):149-163
For dispersed ceria-zirconia-based solid solutions prepared via the polymerized complex method and annealed at 700℃, effects of bulk doping by Ca, Mn, Co, Bi or Nb cations and surface modification by Mn and Pt on their structural features, surface/bulk oxygen reactivity and catalytic activity in methane combustion are considered. With up to 20 mol% doping, a structural type of homogeneous solid solutions of anion-deficient fluorite with disordered anion vacancies is formed. Doping by transition metal cations or Pt increases the mobility and reactivity of the surface/bulk oxygen. A broad variation in specific rates of methane combustion for the studied systems was observed, suggesting structural sensitivity of this reaction. In general, there is no universal relationship between the oxygen mobility, the reactivity and the catalytic activity in methane combustion, which is explained by the factor of specific methane activation on surface active sites. For the Pt-promoted samples, Pt efficiency in methane activation depends on the Pt-support interaction, and the most favorable ones being mixed Pt/MnOx and Pt/NbOx clusters on the surface of the supports that exhibit high lattice oxygen mobilities. 相似文献
6.
G. A. Turko A. S. Ivanova L. M. Plyasova G. S. Litvak V. A. Rogov 《Kinetics and Catalysis》2005,46(6):884-890
Ce-Zr-O and Ce-Zr-Y-La-O materials obtained under various conditions and at varying component ratios are characterized. At Ce/Zr ≈ 1, a tetragonal phase that can hardly be distinguished from a cubic phase by X-ray diffraction forms in the ternary system. Raising the precipitation temperature favors the formation of two-phase systems. Promoting the Ce/Zr = 0.26–0.62 materials with both yttrium and lanthanum favors the formation of a single-phase specimen, namely, a (Ce, Zr, Y, La)O2 fluorite-like solid solution at 600°C. This structure persists up to 1150°C. The specific surface area of the (Ce, Zr, Y, La)O2 materials is primarily determined by their calcination temperature: Ssp = 50–80 m2/g at 600°C and 0.6–0.8 m2/g at 1150° C. The specimens calcined at 600°C are mesoporous, with uniformly sized pores of mean diameter 32 ± 2 Å, and have no micropores. According to TPR data, the specimens calcined at 600°C are reduced with hydrogen in two steps that can apparently be interpreted as surface and bulk reduction. The Ce/Zr = 0.26 and 0.40 specimens calcined at 1150°C are reduced in a single step, giving rise to TPR peaks at 707 and 686°C, respectively, and their degree of reduction increases with decreasing Ce/Zr. 相似文献
7.
E. Ardashev V. Avdeichikov V. Balandin G. Bogdanova V. Dunin O. Gavrishchuk V. Golovkin S. Golovnya S. Gorokhov A. Isupov A. Kazakov A. Kholodenko A. Kiryakov E. Kokoulina A. Kutov N. Kuzmin I. Lobanov V. Nikitin Yu. Petukhov G. Pokatashkin M. Polkovnikov V. Popov S. Reznikov V. Rogov V. Ronzhin I. A. Rufanov V. Ryadovikov Yu. Tsyupa V. Volkov A. Vorobiev N. Zhidkov L. Zolin 《The European Physical Journal A - Hadrons and Nuclei》2016,52(8):261
8.
9.
Doklady Mathematics - 相似文献
10.
V. -B. K. Rogov 《Mathematical Notes》1970,7(2):152-157
The Beltrami-Laplace operator on a one-sheeted hyperboloid is hyperbolic. There is taken the set of functions bounded outside some neighborhood of two isotropic lines, intersecting at infinity. A necessary and sufficient condition is derived that a function of this set be an eigenfunction of the operator .Translated from Matematicheskie Zametki, Vol. 7, No. 2, pp. 255–263, February, 1970. 相似文献