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331.
332.
The present letter demonstrates that a leaky pseudo surface wave (LPSW) should exist on the interface of water and a cubic crystal silicon (110) plane. The phase velocity distribution of the LPSW on the above interface has been theoretically predicted by the reflection coefficient analysis and experimentally measured by using acoustic spectro-microscopy (ASM). The measured phase velocity distribution of the LPSW is in good agreement with the predicted one. 相似文献
333.
Seiya Fukagawa Masahiro Kojima Tatsuhiko Yoshino Shigeki Matsunaga 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(50):18322-18326
Catalytic enantioselective directed methylene C(sp3)?H amidation reactions of 8‐alkylquinolines using a Cp*RhIII/chiral carboxylic acid (CCA) hybrid catalytic system are described. A binaphthyl‐based chiral carboxylic acid efficiently differentiates between the enantiotopic methylene C?H bonds, which leads to the formation of C?N bonds with good enantioselectivity. 相似文献
334.
Yu Zhu Twynam J.K. Yagura M. Hasegawa M. Hasegawa T. Eguchi Y. Amano Y. Suematsu E. Sakuno K. Matsumoto N. Sato H. Hashizume N. 《Electron Devices, IEEE Transactions on》2001,48(11):2640-2646
A simple technique, inserting a specified resistance in the bias circuit, to compensate self-heating effect in DC and pulse characteristics of HBTs is proposed and demonstrated. Utilizing the bias scheme dependence of HBT behaviors, the compensation is achieved due to the cancellation of the positive and negative thermal-electric feedback inside HBTs. An analytical expression relating the specified resistance with the physical parameters of HBT is presented. The accurate simulation of both the self-heating effect and its compensation is, for the first time, demonstrated with a modified Gummel-Poon model 相似文献
335.
Eiki Tomita Kodai Yamada Dr. Yu Shibata Prof. Dr. Ken Tanaka Dr. Masahiro Kojima Dr. Tatsuhiko Yoshino Prof. Dr. Shigeki Matsunaga 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(26):10560-10564
The synthesis, characterization, and catalytic performance of iridium(III) catalysts that bear an amide-pendant cyclopentadienyl ligand ([CpAIrI2]2) is reported. These [CpAIrI2]2 catalysts were obtained from the complexation of a CpA ligand precursor with [Ir(cod)OAc]2 followed by oxidation. Double aromatic homologation reactions of benzamides with alkynes by fourfold C−H activation proceeded in good to high yield with these [CpAIrI2]2 catalysts, demonstrating their superior catalytic performance in this challenging transformation. 相似文献
336.
Narumi Komami Keitaro Matsuoka Ayako Nakano Dr. Masahiro Kojima Dr. Tatsuhiko Yoshino Prof. Dr. Shigeki Matsunaga 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(5):1217-1220
Monoaryl-λ3-iodanes are potentially attractive arylating agents. They are generally synthesized from aryl iodides via oxidation, which can cause functional group incompatibility, especially when polyfunctionalized derivatives are desired. This work describes the direct synthesis of monoaryl-λ3-iodanes through a chemoselective ipso-substitution reaction of arylgermanes and arylstannanes with iodine tris(trifluoroacetate). The generated iodanes were converted to iodonium ylides or used for further transformations in one pot. The presented method enables the preparation of polyfunctionalized monoaryl-λ3-iodanes. 相似文献
337.
Dr. Takuya Shimbayashi Kohei Sasakura Akira Eguchi Dr. Kazuhiro Okamoto Prof. Dr. Kouichi Ohe 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(13):3156-3180
Nitrene-transfer reactions are powerful synthetic tools for the direct incorporation of nitrogen atoms into organic molecules. The discovery of novel nitrene-transfer reactions has been dominantly supported not only by improvements in transition-metal catalysts but also by the employment of novel precursors of nitrenoids. Since pioneering work involving the use of organic azides and iminoiodinanes as practical synthetic tools for nitrogen-containing compounds was reported, a new approach using various N-heterocycles containing strain energy or a weak bond has emerged. In this review, we briefly summarize the history of nitrene-transfer chemistry from the viewpoint of its precursors. In particular, the use of N-heterocycles such as 2H-azirines, 1,4,2-dioxazol-5-ones, 1,2,4-oxadiazol-5-ones, isoxazol-5(4H)-ones, and isoxazoles is comprehensively described, showing the recent remarkable progress in this chemistry. 相似文献
338.
Atsushi Asano Masaru Eguchi Takuzo Kurotu 《Journal of Polymer Science.Polymer Physics》1999,37(16):2007-2012
Thermal dehydration process of PMAA was investigated by solid‐state 13C NMR. For heat‐treated PMAA at 150°C, at which the dehydration goes very slowly, we observed three 13C peaks at 172, 178, and 187 ppm in the carboxyl group region. The peak at 172 ppm is due to the intramolecular cyclic anhydrides by comparing the reported value of 13C chemical shift. The peaks at 178 and 187 ppm were assigned to regularly aligned free carboxylic acids and intermolecular acid dimers, respectively, from the 2D‐exchange 13C NMR spectra, 13C chemical shift values and IR spectra. We concluded that by heat‐treatment the rearrangement of intermolecular hydrogen bonding of the carboxylic acids in PMAA occurs firstly to form the regularly aligned acid dimers, and the dimers dissociated to be the regularly aligned free carboxylic acids at high temperatures. The adjacent free carboxyl acids dehydrate with each other, resulting in the formation of intramolecular anhydrides. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 2007–2012, 1999 相似文献
339.
Naveen Kumar Kaliannan Andres Henao Aristizabal Hendrik Wiebeler Frederik Zysk Tatsuhiko Ohto Yuki Nagata 《Molecular physics》2020,118(4)
ABSTRACTWe have examined the impact of intermolecular vibrational coupling effects of the O-H stretch modes, as obtained by the surface-specific velocity-velocity correlation function approach, on the simulated sum-frequency generation spectra of the water/air interface. Our study shows that the inclusion of intermolecular coupling effects within the first three water layers, i.e. from the water/air interface up to a distance of 6?Å towards the bulk, is essential to reproduce the experimental SFG spectra. In particular, we find that these intermolecular vibrational contributions to the SFG spectra of the water/air interface are dominated by the coupling between the SFG active interfacial and SFG inactive bulk water molecules. Moreover, we find that most of the intermolecular vibrational contributions to the spectra originate from the coupling between double-donor water molecules only, whereas the remaining contributions originate mainly from the coupling between single-donor and double-donor water molecules. 相似文献
340.
Go Hasegawa Tatsuhiko Terai Takuya Okamoto Masayuki Murata 《International Journal of Communication Systems》2004,17(5):389-406
Although many research efforts have been devoted to network congestion in the face of an increase in the Internet traffic, there is little recent discussion on performance improvements for endhosts. In this paper, we propose a new architecture, called scalable socket buffer tuning (SSBT), to provide high‐performance and fair service for many TCP connections at Internet endhosts. SSBT has two major features. One is to reduce the number of memory accesses at the sender host by using some new system calls, called Simple Memory‐copy Reduction (SMR) scheme. The other is equation‐based automatic TCP buffer tuning (E‐ATBT), where the sender host estimates ‘expected’ throughput of the TCP connections through a simple mathematical equation, and assigns a send socket buffer to them according to the estimated throughput. If the socket buffer is short, max–min fairness policy is used. We confirm the effectiveness of our proposed algorithm through both simulation technique and an experimental system. From the experimental results, we have found that our SSBT can achieve up to a 30% gain for Web server throughput, and a fair and effective usage of the sender socket buffer can be achieved. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献