排序方式: 共有19条查询结果,搜索用时 31 毫秒
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Vanga S. Rao 《合成通讯》2013,43(20):2915-2920
A convenient method for the preparation of cis- and trans-1-mercapto-3-azidocyclobutane from 1,1-cyclobutanedicarboxylic acid is described. The long range “W” coupling pathway was used to distinguish the cis isomer from the trans isomer. 相似文献
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Sivarama Krishna Reddy Vanga Hari Babu Bollikolla V. V. Satyanarayana Peruri 《Journal of heterocyclic chemistry》2021,58(3):892-899
An efficient catalyst-free one-pot three-component synthesis of penta-substituted pyrroles has been successfully developed. A variety of penta-substituted pyrroles were straightforwardly synthesized from good to excellent yields (78%–93%) by using easily accessible starting materials under mild conditions. This protocol also provided α-amino ketones in good yields (87%–98%) without column chromatography. 相似文献
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Nagi Reddy Vanga Anudeep Kota Ramakrishna Sistla Mallavadhani Uppuluri 《Molecular diversity》2017,21(2):273-282
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Focused proton beam writing has been utilized to fabricate optical channel waveguides in Nd:GGG crystals. The 1?MeV proton beam irradiation creates a local modified region with positive refractive index changes at the end of the proton trajectory, in which the channel waveguide could confine the light field in a symmetric way. Room-temperature laser emission has been achieved at 1063.7?nm, with absorbed pump power of 61?mW (at 808?nm). The obtained slope efficiency of the Nd:GGG waveguide laser system is as high as 66%, which is, to our best knowledge, the highest value for integrated lasers from ion beam processed channel waveguide systems. 相似文献
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C. Vanga Bouanga K. Fatyeyeva P.-Y. Baillif C. Khaokong J.-F. Pilard M. Tabellout 《Macromolecular Symposia》2010,290(1):175-184
Summary: Composite polyurethane/polyaniline (PU/PANI) films have been chemically prepared by oxidative in-situ polymerization of aniline inside the previously swelled PU film. Swelling kinetic studies have shown that for PU films the swelling degree of aniline is 25 wt.%. The dielectric and electrical properties of the composite films were measured using dielectric relaxation spectroscopy and four-probe method. Dielectric measurements as a function of temperature and frequency revealed the presence of a relaxation process for the composite PU/PANI-HCl film. This relaxation was explained in terms of interfacial polarization due to the double-layered structure of the composite film. The activation energy values found by dielectric and electrical measurements are close and this result confirms the conducting character of the PANI containing layer. 相似文献
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Xiaoyue Huang Ziyou Zhou Raghav Vanga 《Journal of magnetism and magnetic materials》2010,322(23):3777-3783
Control of magnetization is central to the performance of magneto-optical switches and isolators. Photonic crystal technology on these devices can yield significant improvements in polarization rotation efficiency and an overall reduction in device dimensions. The optical response and field reversal characteristics of resonant magneto-optic polarization rotators fabricated on chip are presented herein and analyzed by micromagnetic simulation. By introducing domain-strip structures into the resonant cavity of Bragg gratings formed on magnetic garnet films, a bi-stable magnetic state is demonstrated and the enhancement of characteristic saturation field is studied. Domain closure loops between the strips affect the hysteresis response in the resonant cavity. Large magneto-optic rotations exceeding 45° are produced near resonance between 1500 and 1580 nm in the stop-bands, although the presence of linear birefringence in these gyrotropic waveguides strongly suppresses the Faraday rotation outside the stop-bands and degrades the linearity of the output polarization. 相似文献
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By making photonic crystals in ferroelectric and ferromagnetic materials, field-provoked tunability of photonic crystals is broadening the interest in new applications of on-chip photonic devices. We report a nano-precise fabrication of various designs of photonic crystals in these non-conventional materials using the focused ion beam milling technique. Standard methods are developed and parameters for different materials are calibrated. Optical responses such as bandgaps and polarization status changing from planar film waveguide system with these patterns have been examined on ferromagnetic materials. 相似文献
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Vanga S. Rao 《合成通讯》2013,43(7-8):1389-1393
A convenient method for the preparation of 2-carboxy and 2-alkoxycarbony 1-r-butyrolactones from cyclopropane-1, 1-dicarboxylic acid and their mode of formation is described. A possible conformation for the ring is suggested based on the proton coupling data. 相似文献
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A stereocontrolled total synthesis of (+)-chamuvarinin, isolated from the root extract of Uvaria Chamae, utilizes a convergent modular strategy to construct the adjacently linked C15-C28 ether array, followed by a late-stage Julia-Kocienski olefination to append the butenolide motif. This constitutes the first total synthesis of (+)-chamuvarinin, defining the relative and absolute configuration of this unique annonaceous acetogenin. 相似文献