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411.
Nataliya D. Kundikova Yuri V. Miklyaev Denis G. Pikhulya 《Optics Communications》2012,285(6):1238-1241
The band structure of 3D photonic crystal that could be synthesized by means of interference lithography with triple-exposure two-beam interference technique has been investigated. As a result of the geometry optimization the optimal conditions for maximal band gaps with different refractive index contrast have been obtained. The refractive index threshold for gap opening equaled to 2.14 has been predicted for this method of photonic crystals synthesis. This value is close to the refractive index thresholds of the best known structures. The continuous transition between simple cubic, face centered cubic and bulk centered cubic symmetries has been considered. 相似文献
412.
Alexander V. Artem'ev Svetlana F. Malysheva Nataliya A. Belogorlova Nadezhda I. Protzuk Alexander I. Albanov Irina Yu. Bagryanskaya Elena Yu. Schmidt Nina K. Gusarova Boris A. Trofimov 《Heteroatom Chemistry》2015,26(6):455-462
γ‐Ketophosphine chalcogenides, precursors for plethora of novel functionalized phosphine chalcogenides and phosphines, are synthesized by chemo‐ and regioselective addition of secondary phosphine chalcogenides to β,γ‐ethylenic ketones under catalyst‐ and solvent‐free conditions (80–100°C, 8–70 h) in excellent yields. The straightforward superbase‐catalyzed synthesis of starting β,γ‐ethylenic ketones from ketones and acetylenes insures the expedient access to the target γ‐ketophosphine chalcogenides. 相似文献
413.
Nataliya Kiriy Evelin Jähne Anton Kiriy Hans-Juergen Adler 《Macromolecular Symposia》2004,210(1):359-367
Diverse conformational transitions and aggregations of regioregular poly (3-alkylthiophene)s (PATs) in different environment have been studied by means of AFM and UV-vis-spectroscopy. In methanol, which is a non-solvent for both alkyl side groups and aromatic backbone at low polymer concentration, PATs chains fold into compact poorly ordered flat structures. At higher polymer concentration PATs molecules undergo 3D aggregation into near spherical particles. In hexane, which is a selective solvent for alkyl side chains, PATs molecules undergo ordered main-chain collapse followed by 1D aggregation. Concentration-independent red shift of λmax and good resolved fine vibronic structure in the electronic absorption spectra indicate that planarization occurs on the single-molecule level. 相似文献
414.
Nataliya Kutsevol Tatyana Zheltonozhskaya Nataliya Melnik Jean-Michel Guenet Vladimir Syromyatnikov 《Macromolecular Symposia》2003,203(1):201-206
Conformational changes have been studied in intramolecular polymer-polymer complexes (intraPC) of graft copolymers of poly(acrylamide) and poly(vinyl alcohol) (PVA-g-PAA) with various numbers of grafts (4-42) per molecule as a function of temperature and copolymer concentration. It is shown that the magnitude of conformational change depends on the grafts content while the temperature range over which the conformation changes occur is essentially determined by copolymer concentration. The conformational changes are reversible on heating and cooling. 相似文献
415.
Ol'ga Demchenko Nataliya Kutsevol Tatyana Zheltonozhskaya Vladimir Syromyatnikov 《Macromolecular Symposia》2001,166(1):117-122
The issue of applying the usual concepts of polymer compatibility to nonstoichiometric PVA/PAA mixtures of chemically complementary poly(vinyl alcohol) and poly(acrylamide), which form in water solution InterPC (intermolecular polymer complex) stabilyzed by H‐bonds, and PAA to PVA graft copolymers (PVA‐PAAN) with different grafted chains number N, that are IntraPC (intramolecular polymer complexes) is discussed. PVA and PAA are compatible on molecular level. At the same time PVA/PAA mixture (50/50 W/W) is characterized by heterogeneous structure consists of InterPC with ϕchar=9gPVA/gPAA and the excess of unconnected PAA. In the case of IntraPC, yet, only PVA‐PAAN, where N=25, is characterized by a single glass transition temperature (Tg). At larger values of N separate PAA domains form giving rise to the corresponding Tg. These results are discussed in view of IntraPC structure peculiarities as a function of N investigated by IR spectroscopy. 相似文献