排序方式: 共有51条查询结果,搜索用时 31 毫秒
31.
Baklagina Yu. G. Khripunov A. K. Tkachenko A. A. Gladchenko S. V. Lavrent'ev V. K. Volkov A. Ya. Nilova V. K. Denisov V. M. Sukhanova T. E. Zanaveskina I. S. Klechkovskaya V. V. Feigin L. A. 《Russian Journal of Applied Chemistry》2003,76(6):989-996
The cellulose-producing power of the VKM V-800 Acetobacter xylinum strain under conditions of static culture was studied. The culture medium was optimized with the aim to increase the cellulose yield and obtain highly crystalline cellulose I with molecular weight of about 5 × 105. 相似文献
32.
A mechanism behind the saturation of the photocurrent and occurrence of negative differential photoconductivity in Mn4Si7-Si〈Mn〉-Mn4Si7 and Mn4Si7-Si〈Mn〉-M heterojunctions is found. Mn4Si7-Si〈Mn〉-Mn4Si7 and Mn4Si7-Si〈Mn〉-M structures are studied with a model of back-to-back diodes. Photocurrent-voltage characteristics are taken at high constant and pulsed applied biases. It is found that the nonlinearity of the photocurrent-voltage characteristics and photoconductivity kinetics are due to the quenching of photoconductivity by Joule self-heating. 相似文献
33.
34.
V. V. Klechkovskaya Yu. G. Baklagina N. D. Stepina A. K. Khripunov P. A. Buffat E. I. Suvorova I. S. Zanaveskina A. A. Tkachenko S. V. Gladchenko 《Crystallography Reports》2003,48(5):755-762
The data are presented on optimization of cellulose synthesis by Acetobacter xylinum (strain VKM V-880) and the structural characteristics of A. xylinum cellulose gel film synthesized during static cultivation. The structural changes caused by the removal of water from gel films are established and the structural organization of macromolecular chains in cellulose A. xylinum is studied. 相似文献
35.
Yu. A. D’yakova E. I. Suvorova A. S. Orekhov A. S. Alekseev V. V. Klechkovskaya E. Yu. Tereshchenko N. V. Tkachenko H. Lemmetyinen L. A. Feigin M. V. Kovalchuk 《Crystallography Reports》2011,56(1):157-163
Monolayers of porphyrin-fullerene dyad TBD6a were formed on the surface of a water subphase and then transported on a solid
substrate by the Langmuir-Schaefer method. A simulation was performed for the structure of a single molecule and for a molecular
monolayer, according to the area per molecule in the monolayer formed, which was calculated based on an analysis of the π-A
isotherm. A unit cell was chosen for the proposed molecular packing (a = 1.54 nm, b = 1.50 nm, c = 1.75 nm, α = 80.0°, β = 90.0°, and γ = 90.0°), and the atomic coordinates were calculated. A comparison of the interplanar
spacings and diffraction peak intensities in the experimental and calculated (for the unit cell proposed) diffraction patterns
indicates that a platelike texture is formed in the monolayer and that the crystal structure of the domains corresponds to
the model chosen. 相似文献
36.
V. V. Volkov V. V. Klechkovskaya E. V. Shtykova K. A. Dembo N. A. Arkharova G. I. Ivakin R. Yu. Smyslov 《Crystallography Reports》2009,54(2):169-173
The nanoscale structural features in a composite (gel film of Acetobacter Xylinum cellulose with adsorbed silver nanoparticles, stabilized by N-polyvinylpyrrolidone) have been investigated by small-angle X-ray scattering. The size distributions of inhomogeneities in the porous structure of the cellulose matrix and the size distributions of silver nanoparticles in the composite have been determined. It is shown that the sizes of synthesized nanoparticles correlate with the sizes of inhomogeneities in the gel film. Particles of larger size (with radii up to 100 nm) have also been found. Electron microscopy of thin cross sections of a dried composite layer showed that large particles are located on the cellulose layer surface. Electron diffraction revealed a crystal structure of silver nanoparticles in the composite. 相似文献
37.
Babushkina T. A. Klimova T. P. Shtykova É. V. Dembo K. A. Volkov V. V. Khripunov A. K. Klechkovskaya V. V. 《Crystallography Reports》2010,55(2):312-317
Gel films of Acetobacter Xylinum cellulose and its modified samples have been investigated by 1H nuclear magnetic resonance (NMR) cryoporometry and small-angle
X-ray scattering. The joint use of these two methods made it possible to characterize the sizes of aqueous pores in gel films
and estimate the sizes of structural inhomogeneities before and after the sorption of polyvinylpyrrolidone and Se0 nanoparticles (stabilized by polyvinylpyrrolidone) into the films. According to small-angle X-ray scattering data, the sizes
of inhomogeneities in a gel film change only slightly upon the sorption of polyvinylpyrrolidone and nanoparticles. The impregnated
material is sorbed into water-filled cavities that are present in the gel film. 1H NMR cryoporometry allowed us to reveal the details of changes in the sizes of small aqueous pores during modifications. 相似文献
38.
V. A. Petrova A. S. Orekhov D. D. Chernyakov Yu. G. Baklagina D. P. Romanov S. V. Kononova A. V. Volod’ko I. M. Ermak V. V. Klechkovskaya Yu. A. Skorik 《Crystallography Reports》2016,61(6):945-953
A method for preparing multilayer film composites based on chitosan has been developed by the example of polymer pairs: chitosan–hyaluronic acid, chitosan–alginic acid, and chitosan–carrageenan. The structure of the composite films is characterized by X-ray diffractometry and scanning electron microscopy. It is shown that the deposition of a solution of hyaluronic acid, alginic acid, or carrageenan on a chitosan gel film leads to the formation of a polyelectrolyte complex layer at the interface, which is accompanied by the ordering of chitosan chains in the surface region; the microstructure of this layer depends on the nature of contacting polymer pairs. 相似文献
39.
L. Yanusova V. Klechkovskaya L. Sveshnikova N. Stiopina V. Kruchinin 《Liquid crystals》2013,40(6):1615-1620
Abstract The structure of Langmuir-Blodgett (LB) diacetylene films CH3?(CH2)11?C≡C?C≡C?(CH2)8?COOCd1/2 (DA1) and CH3?(CH2)20?CO2?CH2?C≡C?C≡CH2OH (DA2) was studied by X-ray small angle scattering and electron diffraction methods prior to and upon their polymerization. It has been established that Langmuir films have layer packing. The periods of the constituent layers were determined as 58 Å (for DA1) and 69 Å (for DA2). This indicates the existence of a vertical bilayered packing of molecules. It has also been established that polymerization of LB diacetylene films due to the action of UV irradiation does not change the layer thickness appreciably and the structural rearrangement reduces to a slight redistribution of the electron density along the molecules which is explained by a break of the triple bonds during the UV irradiation. 相似文献
40.
D. M. Shukurova A. S. Orekhov B. Z. Sharipov V. V. Klechkovskaya T. S. Kamilov 《Technical Physics》2011,56(10):1423-1428
The current-voltage characteristics of Mn4Si7-Si〈Mn〉-Mn4Si7 and Mn4Si7-Si〈Mn〉-M photodiodes are studied experimentally. The current passage mechanism under illumination with hν ≥ E
g
is considered. The role of a contact to Mn4Si7 in the provision of high photosensitivity under illumination of the base by light with hν ≥ 1.14 eV at low temperatures, 77–220 K, is analyzed. From electrical measurements, electron microscopic data for the Mn4Si7-Si〈Mn〉 interface, and photocurrent-voltage characteristics, a band diagram under the conditions of photocurrent passage is
constructed. The high low-temperature photosensitivity of the diodes (I
ph/I
d ≥ 109) is explained by the impact-ionization-induced modulation of the base conductivity and injection amplification of holes in
the transition layer. 相似文献