排序方式: 共有42条查询结果,搜索用时 15 毫秒
1.
L. N. Ignatieva V. G. Kuryavyi T. A. Kaidalova V. M. Bouznik A. I. Korchagin 《Journal of Structural Chemistry》2005,46(5):848-855
Electron radiation effects (40 mrad, 70 mrad, and 100 mrad) on the molecular and supramolecular structure and morphology of ultradisperse polytetrafluoroethylene obtained by the thermogas dynamic (TGD) method were studied by IR and EPR spectroscopy, X-ray phase analysis, and atomic force microscopy. Irradiation of ultradisperse powder in air leads to oxidized polymer forms due to the terminal carbonyl groups and stable peroxide radicals that appear in the structure. Fast electron radiation in doses of up to 100 mrad did not change the polymer crystallinity and particle entity, while thin films on the surface of ultradisperse polytetrafluoroethylene powder decomposed. 相似文献
2.
L. N. Ignat'eva V. G. Kuryavyi A. K. Tsvetnikov V. M. Buznik 《Journal of Structural Chemistry》2002,43(5):761-765
The sensitivity of thermogasdynamically dispersed polytetrafluoroethylene to mechanical action was studied by IR and ESR spectroscopy. It is shown that exposure of sample to a pressure of 10 000 kg/cm2 and mechanical impact does not lead to transition from a helical to a planar zigzag conformation but increases the amorphous properties and the number of defects of the sample structure. It is assumed that the defects are due to the appearance of terminal =CF3 groups and =CF3 groups in the side chain or deformation of chain regions with conjugated bonds. 相似文献
3.
D. P. Kiryukhin G. A. Kichigina P. P. Kushch V. G. Kuryavyi V. M. Buznik 《Russian Chemical Bulletin》2013,62(7):1659-1665
The kinetics of radiation telomerization of tetrafluoroethylene in a series of fluorine-containing solvents was studied. A comparative analysis of their reactivity was carried out. The structure and some properties of the telomeres were studied by IR spectroscopy, thermogravimetric and elemental analysis, and electron microscopy. 相似文献
4.
I. V. Kalinovskaya V. G. Kuryavyi P. P. Safronov V. E. Karasev 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2008,82(13):2173-2175
Mechanochemically synthesized europium nitrate with 1,10-phenanthroline (Phen) is formed into globules with sizes of 100–300
nm, which are assembled into larger globular aggregates or packed into layers. The increasing mechanical activation time induces
sintering, generating porous aggregates with micro-and nanopores. Eu2+ paramagnetic centers, detectable by ESR, are generated by mechanical grinding. Possibly, they are positioned on the surfaces
of nanoglobules. The complex Eu(NO3)3 · 2Phen synthesized conventionally from aqueous ethanol consists of needle-shaped microcrystallites. They do not give rise
to ESR spectra. 相似文献
5.
Formation of fluoropolymer nanoaerosols and micropowders in the gas products of polytetrafluoroethylene pyrolysis and the hierarchical self-organization of ultradispersed powders were revealed. The features of the molecular and supramolecular structures of powders were analyzed. Low- and high-molecular-weight fractions of the fluoropolymers, constituting the powder particles were identified, and a method for their partitioning was proposed. 相似文献
6.
7.
The change in the supramolecular structure upon drying (solvent removal) of colloidal solutions of fluoroalkyl oligomers at atmospheric pressure has been studied using atomic force microscopy. In an initial colloidal solution, micrometer-sized particles of the dense phase consist of randomly oriented oligomers in the form of rigid rods of a 3–5 nm length forming a porous framework filled with solvent molecules, which solvate the oligomer chains. The drying-induced capillary pressure, which in nanosized pores is of the same order of magnitude as the solvation energy, leads to framework deformation, collapse of the pores, and the formation of lamellar and dendritic structures on a 50–100 nm scale. The ordering of these structures (formation of blocks of parallel oriented fibers typical of a fluoroplastic) increases as the heat-treatment temperature and the drying rate are increased, increasing the roughness of the surface (ratio of real to smooth surface area) and its hydrophobicity. 相似文献
8.
V. M. Buznik L. N. Ignat’eva V. G. Kuryavyi E. B. Merkulov N. N. Savchenko A. Yu. Ustinov A. B. Slobodyuk L. N. Nikitin 《Polymer Science Series A》2010,52(12):1334-1343
Microsized spherical core-shell particles consisting of hydrocarbon cores encapsulated into fluoropolymer shells are obtained
in supercritical carbon dioxide. Paraffins serve as a core material, while the polymer shell is formed from ultradispersed
polytetrafluoroethylene. The morphology and molecular structure in the bulk and on the surface of the particles and the influence
of conditions of particle formation on the shell thickness and the thermal properties of the materials are studied. The materials
are composites comprised of paraffin cores coated with shells of loosened globular fluoropolymer particles with sizes of 0.2–1.7
μm. The shells is built of low- and high-molecular-mass fractions consisting of CF3(CF2)nCF3 molecular chains with different lengths. The shell thickness is governed by preparation conditions, exposure time, and the
percentage of the polymer in the initial dispersion. 相似文献
9.
P. S. Gordienko I. A. Shabalin A. P. Suponina S. B. Yarusova V. G. Kuryavyi V. V. Zheleznov T. A. Kaidalova D. Kh. Shlyk 《Russian Journal of Inorganic Chemistry》2016,61(8):946-953
Sorption characteristics of synthetic calcium aluminosilicates (CAS) obtained in the multicomponent CaCl2–AlCl3–KOH–SiO2–H2O system are presented. The isotherms of Sr2+ sorption on CAS from aqueous solutions containing no additional salts were measured for Sr2+ concentration from 0.5 to 11.1 mmol/L and solid to liquid phase ratio S: L = 1: 100. The maximum sorption capacity of synthetic CAS was determined, the phase distribution constants of Sr2+ ions at different S: L ratios were found. The recoveries of Sr2+ ions from solutions containing 0.01 mol/L Ca(NO3)2 and from a solution simulating water of the Mayak plant sewage pond No. 11 were determined. 相似文献
10.
Phan AT Kuryavyi V Burge S Neidle S Patel DJ 《Journal of the American Chemical Society》2007,129(14):4386-4392
The c-kit oncogene is an important target in the treatment of gastrointestinal tumors. A potential approach to inhibition of the expression of this gene involves selective stabilization of G-quadruplex structures that may be induced to form in the c-kit promoter region. Here we report on the structure of an unprecedented intramolecular G-quadruplex formed by a G-rich sequence in the c-kit promoter in K+ solution. The structure represents a new folding topology with several unique features. Most strikingly, an isolated guanine is involved in G-tetrad core formation, despite the presence of four three-guanine tracts. There are four loops: two single-residue double-chain-reversal loops, a two-residue loop, and a five-residue stem-loop, which contain base-pairing alignments. This unique structural scaffold provides a highly specific platform for the future design of ligands specifically targeted to the promoter DNA of c-kit. 相似文献