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排序方式: 共有572条查询结果,搜索用时 578 毫秒
91.
The pressure-volume relation of rubidium metal is studied by high-pressure x-ray diffraction up to 110 kbar at room temperature. In addition, pressure scans of the near-infrared reflectivity are recorded up to 250 kbar. Rubidium undergoes a bcc to fcc structural transition (Rb I → Rb II) at 70 ± 2 kbar. Other phase transitions occur at 128 ± 3, 160 ± 5 and 190 ± 5 kbar on the ruby pressure scale. The pressure-volume relation and the near-infrared reflectivity provide evidence for a pressure-induced 5s → 4d electronic transition similar to the well-known 6s → 5d transition in cesium metal. 相似文献
92.
The relation between a nonlinear supersymmetric (NLSUSY) theory and a SUSY Yang–Mills (SYM) theory is studied for N=3 SUSY in two-dimensional space–time. We explicitly show the NL/L SUSY relation for the (pure) SYM theory by means of cancellations among Nambu–Goldstone fermion self-interaction terms. 相似文献
93.
Lee Y Watanabe T Takata T Hara M Yoshimura M Domen K 《The journal of physical chemistry. B》2006,110(35):17563-17569
The photocatalytic activity of beta-Ge(3)N(4) powder for overall water splitting is successfully enhanced by ammonia treatment at 823 K for 5-24 h at ammonia pressures of 20 MPa or greater. The surface and bulk nitrogen content in the treated samples varies according to the treatment temperature and treatment time, related to the stability of beta-Ge(3)N(4) powder under pressurized ammonia. The change in nitrogen content resulted in a change in the photocatalytic activity for overall water splitting. A beta-Ge(3)N(4) powder treated at 823 K for 5 h under ammonia at 20 MPa exhibited a photocatalytic activity 4 times higher than that of the as-synthesized powder, attributable to a decrease in the density of anion defects in the bulk and surface. 相似文献
94.
Xin Wang Takashi Hisatomi Zheng Wang Jun Song Junle Qu Tsuyoshi Takata Kazunari Domen 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(31):10776-10780
LaTaON2 is a photocatalyst with intense visible light absorption up to 650 nm, but exhibits low H2 evolution activity owing to uncontrolled facets and high defect densities. In this work, core–shell‐structured plate‐like LaKNaTaO5/LaTaON2 was synthesized by nitriding a layered perovskite‐type LaKNaTaO5. The volatilization of K and Na species during the nitridation promoted the rapid transformation of LaKNaTaO5 into LaTaON2 along [010] direction with the plate‐like shape retained. This yielded high‐quality LaTaON2 shells exposing (010) facets on the lattice‐matched LaKNaTaO5 cores. After loading with a Rh co‐catalyst, LaKNaTaO5/LaTaON2 showed photocatalytic H2 evolution activity four times greater than that obtained from conventional irregular‐shaped LaTaON2 powders and utilized visible light up to 620 nm. This work provides a novel strategy yielding oxynitrides with well‐defined facets and low defect densities by selecting lattice‐matched oxide precursors containing volatile components. 相似文献
95.
Chisa Higuchi Hiromasa Tanaka Kazunari Yoshizawa 《Journal of computational chemistry》2019,40(1):164-171
The molecular mechanism of the adhesion between silica surface and epoxy resin under atmospheric conditions is investigated by periodic density-functional-theory (DFT) calculations. Slab models of the adhesion interface were built by integrating a fragment of epoxy resin and hydroxylated (0 0 1) surface of α-cristobalite in the presence of adsorbed water molecules. Effects of adsorbed water on the adhesion interaction are evaluated on the basis of geometry-optimized structures, adhesion energies, and forces. Calculated results demonstrate that adsorbed water molecules significantly reduce both the adhesion energies and forces of the silica surface–epoxy resin interface. The reduction of adhesion properties can be associated with structural deformation of water molecules confined in the tight space between the adhesive and adherend as well as structural flexibility of the hydrogen-bonding network in the interfacial region during detachment of the epoxy resin from the hydrophilic silica surface. © 2018 Wiley Periodicals, Inc. 相似文献
96.
We studied the dynamics of photoluminescence (PL) and energy transfer in close-packed monolayer films of CdSe and Au nanoparticles (NPs) assembled using the Langmuir-Blodgett technique. The PL intensity and dynamics depended on the ratio of CdSe to Au NPs in the mixed films. The PL quenching of CdSe NPs occurs through rapid energy transfer from excitons in CdSe NPs to plasmons in Au NPs. The PL decay curves of the mixed NPs monolayers are determined by three decay rates: the direct energy transfer between the nearest-neighbor CdSe and Au NPs (CdSe-->Au), the stepwise energy transfer from CdSe to CdSe to Au NPs (CdSe-->CdSe-->Au), and the radiative recombination in CdSe NPs. 相似文献
97.
Koji Haruta Mina Ye Yu-ichiro Takemura Tomohiro Kobayashi Tatsuo Ishikawa Jhantu Kumar Saha Hajime Shirai 《Journal of Non》2008,354(19-25):2333-2336
The rapid crystallization of amorphous silicon utilizing the radio-frequency (rf) inductive coupling thermal plasma torch of argon is demonstrated. Highly-crystallized Si films were fabricated on thermally grown (th-)SiO2 and textured a-Si:H:B/SnO2/glass by adjusting a distance between the tip of the silica tube and the substrate stage and the translational velocity of the substrate stage. The crystallization was promoted efficiently from the bottom to front surface during the solidification and crystallization of liquid Si. 相似文献
98.
Recently Varagnolo and Vasserot established that theq-deformed Fock spaces due to Hayashi, and Kashiwara, Miwa and Stern, admit actions of the quantum toroidal algebra
with the level (0,1). In the present article we propose a more detailed proof of this fact than the one given by Varagnolo and Vasserot. The quantum toroidal action on the Fock space depends on a certain parameter . We find that with a specific choice of this parameter, the action on the Fock spaces gives rise to the toroidal action on irreducible level-1 highest weight modules of the affine quantum algebra
. Similarly, by a specific choice of the parameter, the level (1,0) vertex representation of the quantum totoidal algebra gives rise to a
structure on irreducible level-1 highest weight
-modules.Supported by the JSPS Research Fellowship for Young Scientists. 相似文献
99.
Here, we describe our studies on the thiourea-catalyzed Morita-Baylis-Hillman (MBH) reaction. Chemoselective activation of carbonyl compounds via hydrogen bonding to thiourea as a catalyst is the key to drastic rate acceleration of this reaction. The application of chiral bis-thiourea-type organocatalysts, which can form a chiral double hydrogen-bonding network, is effective for enantioselective MBH reaction. A cooperative system of bis-thiourea compounds, synthesized from 1,2-diaminocyclohexane, and a Lewis base effectively promotes the MBH reaction at lower temperature, affording the MBH adducts in 33-95% yield with 44-90% ee. A plausible transition state model of the enantioselective MBH reaction is presented. 相似文献
100.
Murakami T Kawasaki T Takemura A Fukutsu N Kishi N Kusu F 《Journal of chromatography. A》2008,1208(1-2):164-174
Rapid and unambiguous identification of three degradation products (DP-1, DP-2 and DP-3) found in heat-stressed loxoprofen sodium adhesive tapes (Loxonin tapes) was achieved by LC-MS and dynamic pressurized liquid extraction (PLE)-solid-phase extraction (SPE) coupled to LC-NMR without complicated isolation or purification processes. The molecular formulae of the degradation products were determined by accurate mass measurements and product ion analyses and on-line hydrogen/deuterium (H/D) exchange experiments provided information about changes in the degradation of loxoprofen. To compensate for the low sensitivity of NMR, on-line dynamic PLE-SPE was employed and higher concentrations of degradation products trapped on the SPE column were afforded in a shorter time than they would be in such time-consuming sample preparations as pre-concentration after extraction. The loop-storage procedure was used in the LC-NMR analysis to allow the acquisition of the (1)H spectra of the three degradation products in one chromatographic run without affecting the peak separation and to avoid the carry-over of previously eluted DP-1 of high concentration by washing the NMR detection cell prior to the measurement of the DP-2 spectrum. Based on the resulting (1)H NMR spectra in combination with the MS results, DP-1 was successfully identified as an oxidation product having an oxodicarboxylic acid structure formed by the cleavage of the cyclopentanone ring of loxoprofen, DP-2 as a cyclopentanone ring-hydroxylated loxoprofen and DP-3 as a loxoprofen l-menthol ester. 相似文献