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971.
K.C. Majumdar Randhir Kumar Sinha Santanu Chakravorty 《Journal of Physics and Chemistry of Solids》2009,70(8):1171-915
The miscibility of a rod-shaped (R) and a bent-shaped (BC) compound forming an induced B1 phase is reported. B1 phase is not present in both R and BC in the entire phase sequence. R exhibits partially bilayered smectic Ad phase with cholesteric and TGB while BC shows a B2 phase. It is interesting to show that the B2 phase is totally diminished in low composition (weight%) of BC, B1 phase is induced at lower temperature range (~90-135 °C). A dielectric study is also incorporated to confirm the induction of B1 phase in the binary mixture. 相似文献
972.
973.
To exploit the parallelism of optics in data processing,a suitable number system and an efficient encoding/decoding scheme for handling the data are very essential.In the field of optical computing and parallel information processing,several number systems like binary,quaternary,octal,hexadecimal,etc.have been used for different arithmetic and algebraic operations.Here,we have proposed an all-optical conversion scheme from its binary to its other 2n radix based form with the help of terahertz optical asymmetric demultiplexer (TOAD) based tree-net architecture. 相似文献
974.
A novel optical burst switching (OBS) high speed network architecture has been proposed. To verify its feasibility and evaluate its performance, just-enough-time (JET) signaling has been considered as a high performance protocol. In the proposed architecture, to avoid burst losses, firstly, a short-prior- confirmation-packet (SPCP) is sent over the control channel that simulates the events that the actual packet will experience. Once SPCP detects a drop at any of the intermediate nodes, the actual packet is not sent but the process repeats. In order to increase network utilization, cost effectiveness and to overcome some limitations of conventional OBS, inherent codes (e.g., orthogonal optical codes (OOC)), which are codified only in intensity, has been used. Through simulations, it shows that a decrease in burst loss probability, cost effectiveness and a gain in processing time are obtained when optical label processing is used as compared with electronic processing. 相似文献
975.
Novel liquid-crystalline phases with layerlike organization 总被引:1,自引:0,他引:1
Cheng XH Das MK Diele S Tschierske C 《Angewandte Chemie (International ed. in English)》2002,41(21):4031-4035
976.
[reaction: see text] Single-electron oxidation has been employed to initiate heterogenerative cascade cyclization reactions that form polyether compounds under essentially neutral conditions. The reactions proceed through mesolytic benzylic carbon-carbon bond cleavages of homobenzylic ether-derived radical cations followed by intramolecular epoxonium ion formation, leading to further cyclizations. Both oligotetrahydrofuran and tetrahydropyran structures can be prepared by altering substrate topography. 相似文献
977.
978.
The dynamics of a single semiflexible filament under the action of a compressing force is simulated. We find that the filament folds asymmetrically with a folding length which depends only on the bending stiffness kappa and the applied force f. It is shown that this behavior can be attributed to the exponentially falling tension profile in the filament. While the folding time tau(0) depends on the initial configuration, the distance moved by the terminal point of the filament and the length of the fold scales as tau(1/2) at tau>tau(0) and is independent of the initial configuration. 相似文献
979.
Mondal Naba Kumar Das Pradyut Kumar Roy Bijan Kumar Ghosh Barindra Kumar 《Transition Metal Chemistry》1999,24(6):678-682
The reaction of [OsX2(HL)(L)] (1) {X = Cl or Br; HL = PhC(O)C(=NOH)Ph (HL1) or PhC(O)C(=NOH)Me (HL2)] with n-BuONO yields mononuclear [OsX(NO)(L1)2] (2) or binuclear [OsX2(NO)(L2)]22 (3) nitrosyls depending on L. The complexes are also obtained by reacting (1) with NaNO2 plus HCl. Molecular weight determinations are in agreement with mono- and binuclear formulations. The diamagnetic orange-red nitrosyls exhibit (NO) at ca. 1890 cm–1 indicating NO+ character of the bound nitrogen monoxide. In 1H-n.m.r. a single sharp L2 methyl signal is in line with the centrosymmetric geometry (4) of the binuclear nitrosyls. The complexes display both spin-allowed and -forbidden charge transfer transitions in the 1000–200 nm range. Both (2) and (3) are electroactive and reductions characteristic of mono- and binuclear compositions are observable on the negative side of s.c.e. They react smoothly with acetylacetone (acacH) in the presence of K2CO3 yielding K[Os(acamo)(L1)2] (5) and K[Os(acac)(acamo)(L2)] (6) [acamo = deprotonated MeC(O)C(=NOH)C(O)Me] respectively. 相似文献
980.
The isomeric compounds 1 and 3, which differ only in the position of a methyl substituent, give opposite chemoselectivities in an esterase-catalyzed hydrolysis reaction. The esterase was chemoselective for the oxoester in 1, but for the thiol ester group in 3. A high enantioselectivity was observed for both 1 and 3. 相似文献