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排序方式: 共有853条查询结果,搜索用时 390 毫秒
841.
Tsutomu Tada Hitoshi FukudaJun Hasegawa Yoshiyuki Oguri 《Spectrochimica Acta Part B: Atomic Spectroscopy》2010
The chemical speciation of phosphorus and sulfur in lake sediment was performed by analyzing Kα X-ray spectra recorded with a high-resolution wavelength-dispersive particle-induced X-ray emission (WD-PIXE) system. The concentrations of phosphorus and sulfur in the sediment were 2500 and 7000 ppm, respectively. To measure both minor elements in a reasonable measurement time, a 2-MeV proton beam with a high current density (6 nA/mm2) was used for the chemical speciation. The possible chemical state change caused by the proton irradiation was studied in order to determine the maximal irradiation time without significant change. We found that the chemical states of phosphorus and sulfur were stable under a beam current density of 6 nA/mm2 and a measurement time of 60 min (phosphorus) and 90 min (sulfur). The chemical states of phosphorus and sulfur were determined to be P5+ and a mixture of S2− and S6+, respectively. 相似文献
842.
A Mesoporous Superlattice Consisting of Alternately Stacking Interstitial Nanospace within Binary Silica Colloidal Crystals
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Dr. Yoshiyuki Kuroda Yosuke Shimbo Prof. Yasuhiro Sakamoto Prof. Hiroaki Wada Prof. Kazuyuki Kuroda 《Angewandte Chemie (International ed. in English)》2016,55(36):10702-10706
A novel class of nonclassical structures of mesoporous silica, namely a binary nanoparticle mesoporous superlattice (BNMS), is obtained by the assembly of silica nanospheres of different sizes into a binary colloidal crystal. The colloidal crystal has a CrB‐type structure and consists of alternate stacks of unary fcc and binary AlB2‐type structures along the b axis and has four types of interstitial mesopores. The BNMS can be deposited on a substrate by dip coating to form an oriented thin film in which the direction of the superstructure (b axis) is perpendicular to the substrate. 相似文献
843.
We numerically investigate the electric potential distribution over a two-dimensional continuum percolation model between the electrodes. The model consists of overlapped conductive particles on the background with an infinitesimal conductivity. Using the finite difference method, we solve the generalized Laplace equation and show that in the potential distribution, there appear quasi-equipotential clusters which approximately and locally have the same values as steps and stairs. Since the quasi-equipotential clusters have the fractal structure, we compute the fractal dimension of equipotential curves and its dependence on the volume fraction over [0,1]. The fractal dimension in [1.00, 1.246] has a peak at the percolation threshold pc. 相似文献
844.
We propose and demonstrate high-quality generation of a uniform multispot pattern (MSP) by using a spatial light modulator with adaptive feedback. The method iteratively updates a computer generated hologram (CGH) using correction coefficients to improve the intensity distribution of the generated MSP in the optical system. Thanks to a simple method of determining the correction coefficients, the computational cost for optimizing the CGH is low, while maintaining high uniformity of the generated MSP. We demonstrate the generation of a 28×28 square-aligned MSP with high uniformity. Additionally, the proposed method could generate an MSP with a gradually varying intensity profile, as well as a uniform MSP consisting of more than 1000 spots arranged in an arbitrary pattern. 相似文献
845.
Tomoaki Terabayashi Dr. Eiichi Kayahara Yichen Zhang Dr. Yoshiyuki Mizuhata Dr. Norihiro Tokitoh Prof. Dr. Tohru Nishinaga Prof. Dr. Tatsuhisa Kato Prof. Dr. Shigeru Yamago 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2023,135(2):e202214960
Mono-alkene-inserted [n]cycloparaphenylenes 1 [(ene)-[n]CPP] with n=6, 8, and 10, mono-ortho-phenylene-inserted [6]CPP 2 , and di-alkene-insertved [n]CPP 3 [(ene)2-[n]CPP] with n=4, 6, and 8 were synthesized by fusing CPP precursors and alkene or ortho- phenylene groups through coupling reactions. Single-crystal X-ray diffraction analyses reveal that the strips formed by the π-surfaces of 1 and 2 exhibited a Möbius topology in the solid state. While the Möbius topology in the parent 1 and 2 in solution was lost due to the free rotation of the paraphenylene unit even at low temperatures, ene-[6]CPP 4 with eight 1-pyrrolyl groups preserved the Möbius topology even in solution. Despite a twist, 1 has in-plane conjugation and possesses a unique size dependence of the electronic properties: namely, the opposite size dependency of the HOMO–LUMO energy relative to conventional π-conjugated molecules. 相似文献
846.
Liping Yao Zhong Zeng Yi Zhang Zhouhua Qiu Hiroshi Mizuseki Yoshiyuki Kawazoe 《Crystal Research and Technology》2012,47(8):816-823
Under a rotating magnetic filed (RMF), the instability of thermocapillary flow and its evolution with increasing Marangoni number (Ma) for semiconductor melt (Pr = 0.01) in a floating liquid bridge model (As = 1) are investigated numerically. Under 5 mT RMF, the thermocapillary flow is steady and axisymmetric with Ma < Mac, and the critical Marangoni number Mac for convection instability is 29.5, which is obtained by the direct numerical simulation. When the Ma is a little bit beyond the Mac, the thermocapillary flow loses stability to become a three‐dimensional rotating oscillatory convection, and a periodic oscillation is confirmed by the fast Fourier transform analysis, the oscillatory main frequency decays with increasing Ma. Under 1 mT–6 mT RMF, the Mac increases roughly with the magnetic strength except the Mac at 4 mT, where the corresponding change of flow mode after the instability is observed. The oscillatory convection occurs with a smaller Ma in the RMF than that without magnetic field. In addition, no instability toward a three‐dimensional steady convection, which is the state of thermocapillary flow without magnetic field after the first instability, is observed under the RMF. 相似文献
847.
Tsuneo Imamoto Takeshi Yoshizawa Koutaro Hirose Yoshiyuki Wada Hideki Masuda Kentaro Yamaguchi Hiroko Seki 《Heteroatom Chemistry》1995,6(2):99-104
(SP)-9-Anthryl(l-menthyloxy)phenylphosphine-borane and (SP)-(1-l-menthyloxy)benzo[b]phosphole-borane were synthesized, and their structures were characterized by X-ray crystallographic analysis. The latter compound was reduced by lithium naphthalenide at −78°C with cleavage of the P O bond, and the subsequent reaction with electrophiles afforded the corresponding tertiary phosphine-boranes possessing good to excellent enantiomeric excesses. 相似文献
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