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91.
A. A. Korolev V. E. Shiryaeva T. P. Popova E. N. Viktorova A. A. Kurganov 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2010,84(4):668-672
Divinylbenzene polymer monolithic capillary columns were prepared on the basis of capillaries 0.01 to 0.53 mm in diameter. Separation properties of the columns were investigated with the use of a test mixture of light hydrocarbons. The permeability and C parameter in the Van Deemter equation were determined for all the columns. For the most part, the columns had similar characteristics: permeability was in the range (2.2 ± 0.2) × 10?9 cm2, with parameter C in the range (0.7 ± 0.2) × 10?3 s (with n-butane as a sorbate). It was thus established that capillary diameter has only a slight effect on the efficiency of monolithic capillary columns (unlike packed capillary columns and microcolumns, whose properties, according to the literature data, depend strongly on the column diameter). The difference in properties between the narrowest monolithic column (capillary diameter 0.01 mm) and the others is explained by column overloading. 相似文献
92.
T. V. Povarnitsyna N. R. Popova K. G. Bogolitsyn A. L. Beloglazova A. N. Pryakhin V. V. Lunin 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2010,84(12):2051-2055
The kinetics of catalytic oxidation for ferulic acid with polyoxometalates used as catalysts was studied. The effect of pH
and concentrations of the principal reacting components on the process kinetics was studied. A kinetic scheme of oxidation
is proposed, and the values of a number of kinetic parameters of the process are determined. 相似文献
93.
Yu. A. Popov N. A. Koval’chukov G. N. Shikin V. A. Popova 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2010,84(12):2143-2147
A theoretical model of the nucleation of a passivating salt layer on the surface S of an anode-dissolving metal was developed.
The layer is considered a new phase formed by the mechanism of heterogeneous nucleation, which serves as a related substrate
for subsequent growth of the passivating layer. According to experiments, the surface S of real metals is inhomogeneous, that
is, anode current density fluctuates on S. It is assumed that, at large current fluctuations, localized regions with volume
ΔV
ϕ appear, in which the C
M and C
A concentrations of the M
z+ and A
n− ions are increased. At fairly large current fluctuations, these concentrations can reach saturation. For this reason, the
ΔV
ϕ regions are treated as mother phases, in which A
a
M
m
salt nuclei are formed with a certain probability. The formation of such ΔV
ϕ volumes and the kinetics of formation of nuclei in them, from which a passivating layer with a finite thickness is formed,
are considered. 相似文献
94.
Dalinger I. L. Vatsadse I. A. Shkineva T. K. Popova G. P. Ugrak B. I. Shevelev S. A. 《Russian Chemical Bulletin》2010,59(8):1631-1638
A method of preparation of 5-amino-3,4-dinitropyrazole (1) from 3(5)-methyl-5(3)-nitro- and 3(5)-methyl-4,5(3)-dinitropyrazoles was developed, the key step of which was the Hofmann
rearrengement of nitro- and dinitropyrazolecarboxamides. The protonation of 5-amino- 3,4-dinitropyrazole was studied by spectral
methods (UV spectroscopy, NMR spectroscopy). In spite of low basicity of the amino group, compound 1 undergoes N-arylation, N-nitration, and annulation reactions with formation of dinitropyrazolo[5,1-a]pyrimidine derivatives and hitherto unknown dinitroimidazo[1,2-b]pyrazole derivatives. Diazotization of 1 leads to 5-diazo-3,4-dinitropyrazole (19), which exists in the form of the internal salt. Some reactions of this compound were studied and the formation of the corresponding
5-halogeno(azido)- 3,4-dinitropyrazoles under the action of the halide and azide ion was shown. Dinitropyrazolo- [5,1-c][1,2,4]triazine and 7-hydroxydinitro-4,7-dihydropyrazolo[5,1-c][1,2,4]triazine deriva- tives were obtained by the action of active methylene compounds on the betaine 19. 相似文献
95.
The data in the literature and our results of studying the piezoelectric effect in ferroelectric liquid crystals are analyzed. The existing theories of this effect in liquid crystals are discussed. The parametric transformations of electromechanical oscillations in ferroelectric liquid crystals are considered. 相似文献
96.
Popova A. A. Shikin A. M. Rybkin A. G. Marchenko D. E. Vilkov O. Yu. Makarova A. A. Varykhalov A. Yu. Rader O. 《Physics of the Solid State》2011,53(12):2539-2544
A study is reported of the role played by covalent interaction in the coupling of graphene formed on Ni(111) to the Ni substrate
and after intercalation of Au and Cu monolayers underneath the graphene. Covalent interaction of the graphene π states with
d states of the underlying metal (Ni, Au, Cu) has been shown to bring about noticeable distortion of the dispersion relations
of the graphene electronic π states in the region of crossing with d states, which can be described in terms of avoided-crossing effects and formation of bonding and antibonding d-π states. The overall graphene coupling to a substrate is mediated by the energy and occupation of the hybridized states
involved. Because graphene formed directly on the Ni(111) surface has only bonding-type occupied states, the coupling to the
substrate is very strong. Interaction with intercalated Au and Cu layers makes occupation of states of the antibonding and
bonding types comparable, which translates into a weak resultant overall coupling of graphene to the substrate. As a result,
after intercalation of Au atoms, the electronic structure becomes similar to that of quasi-free-standing graphene, with linear
dispersion of π states at the K point of the Brillouin zone and the Dirac point localized close to the Fermi level. Intercalation of Cu atoms under the graphene
monolayer results, besides generation of covalent interaction, in a slight charge transport, with a partial occupation of
the previously unoccupied π* states and the Dirac point shifted by 0.35 eV toward increasing binding energy. 相似文献
97.
Yu.D. Zavorotnev L.I. MedvedevaB.M. Todris E.A. DvornikovO.Yu. Popova 《Journal of magnetism and magnetic materials》2011,323(22):2808-2812
Experimental data on magnetization of the antiferromagnetic (AFM) polycrystalline samples in the temperature range of 20-300 K, for pressures of 2 kbar and in magnetic field of 300 kOe, are presented in the paper. In the fields of 250 kOe, the magnetization curve demonstrates a jump explained by exchange-interaction sign change. In the region of 50-70 kOe, on the differential susceptibility versus magnetic field curve, there is a break of the 2nd order corresponding to the anomalous behavior of the magnetization. The obtained results were processed on the basis of the phenomenological Landau theory. It is shown that the ferromagnetic vector occurrence is forced during the formation of AFM spiral structure. The behavior of thermodynamic potential factors has been determined. Three more anomalies have been revealed and explained by a jump-like magnetization change of the Co-subsystem. 相似文献
98.
O. V. Popova 《Siberian Mathematical Journal》2012,53(1):152-167
We establish necessary and sufficient conditions for various Hardy-type inequalities on the cones of monotone functions. 相似文献
99.
Yu. S. Kochergin T. I. Grigorenko O. S. Popova E. E. Samoilova 《Polymer Science Series D》2010,3(4):231-234
The results of investigations of epoxy polymers cured with polyoxypropylene diamine D-230 depending on the molecular weight
of epoxide oligomer, the content of the curing agent, active diluents, and plasticizers are presented. It is shown that epoxy
polymers cured with polyoxypropylene diamine are characterized by a rather high complex of physicomechanical and adhesion
properties. 相似文献
100.