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I. K. Polushina Yu. V. Rud’ T. N. Ushakova V. Yu. Rud’ 《Physics of the Solid State》1999,41(7):1084-1087
The first results obtained in studies of the temperature dependences of electrical conductivity and Hall constant of n-CdGeAs2 single crystals prepared by low-temperature crystallization are reported. It has been established that the method developed
permits growing single crystals with a free-electron concentration ⋍(1−2)×1018 cm−3 and a Hall mobility ⋍10000 cm2/(Vs) at T=300 K. It is shown that the temperature dependence of Hall mobility exhibits a behavior characteristic of electron scattering
by lattice vibrations, whereas below 150 K a deviation from this law is observed to occur evidencing an increasing contribution
of static lattice defects to scattering. The Hall mobility in the crystals prepared was found to reach ⋍36000 cm2/(Vs) at 77 K. Photosensitive heterojunctions based on n-CdGeAs2 single crystals were prepared. The spectral response of the photosensitivity of these structures is analyzed. It is concluded
that this method is promising for preparation of perfect CdGeAs2 crystals.
Fiz. Tverd. Tela (St. Petersburg) 41, 1190–1193 (July 1999) 相似文献
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Mariya E. Mikhailova Galina E. Polushina Alexander B. Mel’nikov Andrey V. Lezov 《International Journal of Polymer Analysis and Characterization》2015,20(2):130-137
The conformational and dynamo-optical properties of a homologous series of polymethacrylate modified by first-generation Fréchet-type dendrons in the molecular mass range of 70–8800 kDa in organic solvents were studied by viscometry, isothermal diffusion, dynamic light scattering, and flow birefringence. The Mark-Kuhn-Houwink equations for this dendronized polymer in toluene and chloroform together with hydrodynamic diameter and Kuhn segment length in toluene are defined as well as the value of intrinsic anisotropy of polarizability for the monomer unit. 相似文献
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A. V. Lezov A. B. Mel’nikov S. K. Filippov G. E. Polushina E. A. Antonov M. E. Mikhailova E. I. Ryumstev 《Polymer Science Series A》2006,48(3):325-331
The molecular characteristics of polystyrene modified by the Frechet type dendrons of 1–4 generations were studied in tetrahydrofuran by viscometry, isothermal diffusion, electric birefringence, and dynamic and static light scattering. It was shown that dendronized polystyrene molecules whose polymerization degree changes from 1640 to 930 with an increase in the generation number of dendrons occur in the coillike conformation. The equilibrium rigidity of macromolecules tends to increase with increasing the generation number of dendrons. The Kuhn segment length grows from 3.9 nm for polystyrene molecules modified by dendrons of the first generation to 23.3 nm for polystyrene molecules carrying dendrons of the fourth generation. 相似文献
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V. A. Mamedov V. L. Polushina F. F. Mertsalova I. A. Nuretdinov 《Russian Chemical Bulletin》1992,41(1):170-171
The reaction of 2,2-dichloroacetophenone with benzaldehydes was studied under Darzens condensation conditions. Benzaldehyde, p-bromobenzaldehyde, and o,p-dichlorobenzaldehyde condensed with 2,2-dichloroacetophenone to give 1-phenyl-3-aryl-3-chloro-1,2-propanediones. In the case of p-nitrobenzaldehyde, 1-phenyl-2-chloro-3-(p-nitrophenyl)-2,3-epoxy-1-propanone, which is the product of the first step of the Darzens condensation, was isolated.A. E. Arbuzov Institute of Organic and Physical Chemistry, Kazan Science Center, Russian Academy of Sciences, 420083 Kazan. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 1, pp. 204–206, January, 1992. 相似文献
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Conclusions In solutions of 2,2-dichlorovinyl alkyl ethers, the s-trans conformation or a very similar conformation is realized.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 557–559, March, 1986. 相似文献
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A. V. Lezov P. S. Vlasov A. A. Lezov N. S. Domnina G. E. Polushina 《Polymer Science Series A》2011,53(11):1012-1018
Viscometry and dynamic and static light scattering are employed to study the molecular properties of water-soluble poly(carboxybetaine),
that is, poly(2-(diallyl(methyl)ammonium) acetate). It is shown that, in solutions with pH 1, the polymer behaves as a polyelectrolyte.
In media with pH 6 and 13, an increase in the concentration of sodium chloride increases the intrinsic viscosity of the polymer
and the hydrodynamic radius of its macromolecules, thereby indicating the antipolyelectrolyte effect typical of polymer zwitterions.
In water and 0.1 M NaOH, the second virial coefficient of the polymer is close to zero, while exponent ν, which relates the sizes of macromolecules to their molecular masses, is 0.5. In 1 M NaCl, the second virial coefficient
becomes positive, while exponent increases to 0.58. The Kuhn segment lengths of poly(carboxybetaine) molecules are 6.3 and
6.6 nm in water and 1 M NaCl, respectively. An increase in the hydrodynamic radius of macromolecules with the ionic strength
of the solution is due to the shielding of attraction between zwitterions belonging to polybetaine monomer units located far
apart along a macromolecular chain. 相似文献
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The review summarizes the results of electric-birefringence studies of the molecular properties of biopolymers and their complexes. The application of alternating electric fields makes it possible to study the kinetics of orientation of DNA, RNA, and polypeptide molecules in diluted solutions. An analysis of molecular-mass dependences of relaxation times of biopolymer molecules in terms of the rotational friction theory is used to determine the equilibrium rigidity of macromolecules characterized by Kuhn segment length A. For DNA molecules in buffer solutions with a low ionic strength, the value of A derived from electro-optical measurements is 114 nm. The high sensitivity of electric birefringence to changes in the secondary and tertiary structures of biopolymers ensures its use for the analysis of sequence curvature in short fragments of DNA and for investigation of transitions between different tertiary structures of RNA. The study of electro-optical birefringence in solutions of complexes of DNA and polypeptides with oppositely charged ions of surfactants makes it possible to gain insight into their conformational properties in organic solvents. The stoichiometric complexes of DNA in chloroform occur in the compact globular state, whereas the conformation of complexes formed by various polypeptides depends on their composition and may vary from rodlike to coiled. Electric birefringence in solutions of biopolymer complexes is associated with the orientation of molecules that is due to the external-field-induced dipole moment that appears as a result of a small displacement of ions along the contour of polyion chains. The time of reaching the induced dipole moment is equal to or greater than the time of orientational relaxation of the complex as a whole. 相似文献