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71.
Melko RG Paramekanti A Burkov AA Vishwanath A Sheng DN Balents L 《Physical review letters》2005,95(12):127207
We study the interplay of Mott localization, geometric frustration, and superfluidity for hard-core bosons with nearest-neighbor repulsion on the triangular lattice. For this model at half filling, we demonstrate that superfluidity survives for arbitrarily large repulsion, and that diagonal solid order emerges in the strongly correlated regime from an order-by-disorder mechanism. This is thus an unusual example of a stable supersolid phase of hard-core lattice bosons at a commensurate filling. 相似文献
72.
We describe and justify a simple model for the dynamics associated with rapid sweeps across a Feshbach resonance, from the atomic to the molecular side, in an ultracold Fermi system. The model allows us to relate the observed molecule momentum distribution to equilibrium properties of the initial state. In particular, the dependence of the total molecule number on the sweep rate is found to be a sensitive probe of pairing in the initial state, whether condensed or not. This can be used to establish the presence of a phase fluctuation induced "pseudogap" phase in these systems. 相似文献
73.
Thermal transport in the mixed state of a d-wave superconductor is considered within the weak-field regime. We express the thermal conductivity, kappa(xx), and the thermal Hall conductivity, kappa(xy), in terms of the cross section for quasiparticle scattering from a single vortex. Solving for the cross section (neglecting the Berry phase contribution and the anisotropy of the gap nodes), we obtain kappa(xx)(H,T) and kappa(xy)(H,T) in surprisingly good agreement with the qualitative features of the experimental results for YBa2Cu3O6.99. In particular, we show that the simple, yet previously unexpected, weak-field behavior, kappa(xy)(H,T) approximately T squareroot [H], is that of thermally excited nodal quasiparticles, scattering primarily from impurities, with a small skew component provided by vortex scattering. 相似文献
74.
We present a novel electrochemical approach to grow copper phthalocyanine (CuPc) thin-film photoelectrodes through anodic oxidation of copper and dilithium phthalocyanine (Li2Pc). This circumvents the challenges associated with the electrochemical processing of unsubstituted CuPc from solution. The potentiostatic co-electrooxidation reaction at the heterogeneous interface favors the growth of CuPc thin film. The surface morphology of thin film exhibits nanorod-like features. UV-Vis, grazing angle Fourier transform infrared (FTIR), and grazing angle X-ray diffraction patterns reveal that the nanocrystalline phase corresponds only to α-CuPc and no admixture of other polymorphs. Photocurrent measurement shows a stable photoresponse in neutral medium. The photoelectrochemical hydrogen evolution on p-type CuPc coated copper photocathode shows an enhanced activity over bare copper and indium tin oxide (ITO) electrodeposited with CuPc and monolithium phthalocyanine radical (LiPc) thin films. 相似文献
75.
Alexandreas DE Allen RC Berley D Biller SD Burman RL Cady DR Chang CY Dingus BL Dion GM Ellsworth RW Gilra MK Goodman JA Gupta S Haines TJ Hoffman CM Krakauer DA Kwok P Lloyd-Evans J Lu XQ Nagle DE Potter ME Sandberg VD Stark MJ Talaga RL Vishwanath PR Yodh GB Zhang W 《Physical review D: Particles and fields》1991,43(5):1735-1738
76.
The proposed methods allow semimicro and microlevel determination of SBS in authentic samples and in dosage forms. The spectrophotometric
method is much more sensitive than most of the procedures known for the determination of SBS. The titrimetric method takes
less than 15 min for analysis. All the procedures are simple and do not need elaborate treatment or tedious extractions. One
titrimetric and two spectrophotometric methods are described for the assay of sulbutamol sulphate (SBS) in bulk drugs and
in tablets using bromate-bromide mixture and two dyes, rhodamine B and methylene blue, as reagents. In titrimetry, an aqueous
solution of SBS is treated with a measured excess of bromate-bromide mixture in a HCl medium, followed by iodometric determination
of unreacted bromine. Spectrophotometric methods involve the addition of a known excess of bromate-bromide mixture to SBS
in an acid medium, followed by the determination of residual bromine by reacting with either a fixed amount of rhodamine-B
and measuring the absorbance at 555 nm (method A) or methylene blue and measuring the absorbance at 665 nm (method B). In
all methods, the amount of in situ generated bromine reacted corresponds to the amount of SBS. The titrimetric method is applicable
over the 3.0–8.0 mg range and the reaction stoichiometry is found to be 1: 2 (SBS: KBrO3). In spectrophotometric methods, the absorbance is found to increase linearly with the concentration of SBS which is corroborated
by the correlation coefficient of 0.9978 and 0.9991 for method A and method B, respectively. The systems obey Beer’s law for
0.25–2.5 μg/mL (method A) and 0.75–7.5 μg/mL (method B). The calculated apparent molar absorptivity values are found to be
8.96 × 104 and 4.67 × 104 L mol−1 cm−1, for method A and method B, respectively, and the corresponding Sandell sensitivity values are 6.43 and 12.34 ng/cm2. The limits of detection and quantification are also reported for both spectrophotometric methods. Intraday and interday
precision and accuracy of the methods were evaluated. The methods were successfully applied to the assay of SBS in tablet
and capsule preparations and the results were compared with those of a reference method by applying Student’s t-and F-tests. No interference was observed from common pharmaceutical ajuvants.
The text was submitted by the authors in English. 相似文献
77.
B. G. Soares Fernando G. SouzaJr A. Manjunath H. Somashekarappa R. Somashekar Siddaramaiah 《Pramana》2007,69(3):435-443
Small angle X-ray scattering data have been recorded for the blends of styrene butadiene, styrene copolymer/polyaniline using
the beamline of the LNLS (Laboratorio Nacional de Luz sincroton-Campinas, Brazil). Employing one-dimensional Hosemann’s paracrystalline
model, we have simulated the meridional reflections of these blends in order to compute the long periodicity and hence to
find the variation with concentrations of the blends. Within the region of available experimental data we observe that there
is a linear relationship between long periodicity and concentration of blends. These parameters are compared with physical
measurements like tensile strength to find the structure-property relation in these blends.
相似文献
78.
Dr. Vishwanath Kalyani Dr. V. S. V. Satyanarayana Dr. Vikram Singh Dr. Chullikkattil P. Pradeep Dr. Subrata Ghosh Dr. Satinder K. Sharma Prof. Kenneth E. Gonsalves 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(5):2250-2258
Two new polyoxometalate (POM)‐based hybrid monomers (Bu4N)5(H)[P2V3W15O59{(OCH2)3CNHCO(CH3)C?CH2}] ( 2 ) and (S(CH3)2C6H4OCOC(CH3)=CH2)6[PVMo10O40] ( 5 ) were developed by grafting polymerizable organic units covalently or electrostatically onto Wells–Dawson and Keggin‐type clusters and were characterized by analytical and spectroscopic techniques including ESI‐MS and/or single‐crystal X‐ray diffraction analyses. Radical initiated polymerization of 2 and 5 with organic monomers (methacryloyloxy)phenyldimethylsulfonium triflate (MAPDST) and/or methylmethacrylate (MMA) yielded a new series of POM/polymer hybrids that were characterized by 1H, 31P NMR and IR spectroscopic techniques, gel‐permeation chromatography as well as thermal analyses. Preliminary tests were conducted on these POM/polymer hybrids to evaluate their properties as photoresists using electron beam (E‐beam)/extreme ultraviolet (EUV) lithographic techniques. It was observed that the POM/polymer hybrid of 2 with MAPDST exhibited improved sensitivity under EUV lithographic conditions in comparison to the MAPDST homopolymer resist possibly due to the efficient photon harvesting by the POM clusters from the EUV source. 相似文献
79.
We study Aharonov-Bohm (AB) conductance oscillations arising from the surface states of a topological insulator nanowire, when a magnetic field is applied along its length. With strong surface disorder, these oscillations are predicted to have a component with anomalous period Φ(0)=hc/e, twice the conventional period. The conductance maxima are achieved at odd multiples of 1/2Φ(0), implying that a π AB phase for electrons strengthens the metallic nature of surface states. This effect is special to topological insulators, and serves as a defining transport property. A key ingredient, the surface curvature induced Berry phase, is emphasized here. We discuss similarities and differences from recent experiments on Bi2Se3 nanoribbons, and optimal conditions for observing this effect. 相似文献
80.
We have computed γ-ray exposure buildup factors (EBF) of some building materials; glass, marble, flyash, cement, limestone, brick, plaster of paris (POP) and gypsum for energy 0.015–15 MeV up to 40 mfp (mfp, mean free path) penetration depth. Also, the macroscopic effective removal cross-sections (ΣR) for fast neutron were calculated. We discussed the dependency of EBF values on photon energy, penetration depth and chemical elements. The half-value layer and kinetic energy per unit mass relative to air of building materials were calculated for assessment of shielding effectiveness. Shielding thicknesses for glass, marble, flyash, cement, limestone and gypsum plaster (or Plaster of Paris, POP) were found comparable with ordinary concrete. Among the studied materials limestone and POP showed superior shielding properties for γ-ray and neutron, respectively. Radiation safety inside houses, schools and primary health centers for sheltering and annual dose can be assessed by the determination of shielding parameters of common building materials. 相似文献