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排序方式: 共有297条查询结果,搜索用时 15 毫秒
1.
Hirohisa Yokota Kenji Kamoto Jun-ichi Igarashi Norihiko Mouri Yutaka Sasaki 《Optical Review》2002,9(1):9-12
A new configuration for an ASE reduction filter in EDFA repeaters for WDM optical transmission systems using optical fiber grating couplers (FGCs) was proposed and first demonstrated. The filtering characteristics of the proposed filter for amplified single wavelength signal and 2-channel WDM signals using EDFA were identified. It was found that the filter was effective to improve SNR in optical domain by reducing ASE noise. The required FGC characteristics for the filter were theoretically predicted under the condition that the total filter loss did not exceed 3 dB. More than 70% of drop efficiency was required in each FGC for the application of the proposed filter to an 8-channel WDM system using EDFA repeaters. 相似文献
2.
Selective oxidation of an AlInAs layer was investigated for enhancement of magneto-optic effect in an optical isolator. Twelve times nonreciprocal phase shift enhancement was estimated from a measured AlInAs-oxide refractive index. 相似文献
3.
Two types of optical current transducers (OCTs) have a bulk Faraday sensor inserted into the gap of an iron core and a porcelain
insulator with optical fiber. The sensor consists of Bi12SiO20 (BSO) single crystal, a polarizer, and an analyzer. The OCTs satisfied the target performance requirement for fault location
and metering and demonstrated maintained performance at some power utilities in Japan and the US. We have developed a fault
location system that immediately detects the fault current with the OCTs, there by locating the fault section. The OCT can
easily replace the existing support insulators for the disconnecting switch without any modifications to structure height
or bus-bar. For metering requiring 0.3% class accuracy, use of a BSO with right optical rotatory power combined with BSO with
left optical rotatory power results in a Faraday sensor with improved temperature characteristics. The OCT demonstrated 0.3%
class accuracy for metering described in the current transformer Specifications of IEEE C57–13, 1993. 相似文献
4.
The [3,3]-sigmatropic rearrangement took place smoothly during the course of trifluoroacetylation of O-phenyloxime at below room temperature to give the dihydrobenzofuran or benzofuran as a result of concomitant cyclization. 相似文献
5.
Kazutoshi Shindo Ryoko NakamuraIkuko Chinda Yasuo OhnishiSueharu Horinouchi Haruko TakahashiKazuo Iguchi Shigeaki HarayamaKensuke Furukawa Norihiko Misawa 《Tetrahedron》2003,59(11):1895-1900
The bphA1(2072)A2A3A4 gene cluster codes for a shuffled biphenyl dioxygenase holoenzyme with broad substrate specificity. These bphA1(2072)A2A3A4 genes were expressed in the actinomycetes Streptomyces lividans using a thiostrepton-inducible promoter PtipA. Biotransformation experiments of various aromatics including carboxylic acid or amine in their molecular structure, such as 1-naphthoic acid, 2-(1-naphthyl)acetic acid, diphenylamine, and 1-benzyl-4-piperidone, were performed using the recombinant S. lividans cells. These ionized aromatics were converted to the corresponding 1,2-dihydrodiol, mono- or tri-hydroxy forms in 48 h. The structure of the converted products was determined by their EI-MS, 1H- and 13C NMR analysis, and several products were found to be novel compounds. 相似文献
6.
Kouichi Ohe Tomomi Yokoi Koji Miki Fumiaki Nishino Sakae Uemura 《Journal of the American Chemical Society》2002,124(4):526-527
The reaction of cis vicinal acetylethynylcyclopropanes 1 with a catalytic amount of M(CO)5(THF) (M = Cr or W) in the presence of Et3N at room temperature gave ortho-substituted phenols 7 in good yields as valence isomerized products. In the absence of Et3N the reactions did not work at all. The reaction of a cyclopropane having an ester or an amide instead of an acetyl moiety with M(CO)5(THF) did not take place, whereas an ethynylvinylcyclopropane gave a mixture of 1- and 2-substituted 1,3,5-cycloheptatrienes. These valence isomerization reactions are assumed to proceed via the formation of vinylidene-metal intermediates 2 from terminal alkynyl moieties followed by [3,3]sigmatropy of 2 to give seven-membered carbene complexes 3. 相似文献
7.
Polyanionic glycopolymers were synthesized aiming at establishing a simple process for assembling glycosyl arrays. The synthetic glycopolymers carry the key carbohydrate epitopes of α-d-galactobioside (Gb2), β-lactoside, and α-d-mannopyranoside, each of which serves as a ligand of bacterial toxins and adhesion proteins. The Gb2 epitope, prepared from penta-O-acetyl-d-galactopyranose, was coupled with poly(ethylene-alt-maleic anhydride) in a polymer reaction to afford a Gb2-embedded glycopolymer having also carboxylate (COO−) polyanions at the side chain. The polyanionic glycopolymer was then applied to a preparation of sugar-coated gold electrodes, which involves an alternating layer-by-layer adsorption based on electrostatic interactions. The presence of the Gb2-coat on the surface was evidenced by Fourier transform infrared reflection absorption spectroscopy. The Gb2-coated glyco-chip was stable in 10 mM HEPES buffer containing 150 mM NaCl aq. Other glycopolymers carrying the β-lactoside and α-d-mannopyranoside epitopes were applied to the same assembling process. The derived glycosyl arrays will be useful for detecting Shiga toxins, other pathogenic toxins and viruses when applied as glyco-chips for surface plasmon resonance or quartz crystal microbalance technique. 相似文献
8.
Miyazaki A Fujisawa Y Shiotani K Fujita Y Li T Tsuda Y Yokoi T Bryant SD Lazarus LH Okada Y 《Chemical & pharmaceutical bulletin》2005,53(9):1152-1158
1,2-Dihydropyrazin-2-one derivatives, which have two aminoalkyl groups at the positions 3 and 6, were found to be efficient tools for the construction of potent, selective and long-acting opioid mimetics. During the course of preparation, we found that the catalytic hydrogenation of 3,6-bis(benzyloxycarbonylaminomethyl)-5-methyl-1,2-dihydropyrazin-2-one to remove the benzyloxycarbonyl groups resulted in a side reaction. By MS and NMR studies and by preparation of additional 1,2-dihydropyrazin-2-one derivatives, the structure of the by-product was identified as 3-aminomethyl-5,6-dimethyl-1,2-dihydropyrazin-2-one. Preparation of additional compounds substituted with deuterium provided us with sufficient information to confirm the structure of the product and to support a cyclization mechanism in its formation. 相似文献
9.
Kyoichi Hanada Juntaro Nogami Prof. Dr. Kazunori Miyamoto Norihiko Hayase Dr. Yuki Nagashima Yusuke Tanaka Dr. Atsuya Muranaka Prof. Dr. Masanobu Uchiyama Prof. Dr. Ken Tanaka 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(36):9313-9319
The enantioselective synthesis of aza[6] and [7]helicene-like molecules have been achieved by the cationic rhodium(I)/axially chiral biaryl bisphosphine complex-catalyzed intramolecular [2+2+2] cycloaddition of cyanodiynes. This protocol was successfully applied to the diastereo- and enantioselective synthesis of an S-shaped double aza[6]helicene-like molecule with a high ee value of 89 %. Although no epimerization and racemization were observed in the double carbo[6]helicene-like molecule at 80 °C, epimerization and racemization of the double aza[6]helicene-like molecule proceeded at 80 °C. This double aza[6]helicene-like molecule showed good fluorescent quantum yields and chiroptical responses under both neutral and acidic conditions. 相似文献
10.
Dr. Ding‐Bang Xiong Dr. Norihiko L. Okamoto Dr. Takeshi Waki Dr. Yufeng Zhao Dr. Kyosuke Kishida Prof. Dr. Haruyuki Inui 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(9):2536-2542
Heusler phases, including the full‐ and half‐Heusler families, represent an outstanding class of multifunctional materials on account of their great tunability in compositions, valence electron counts (VEC), and properties. Here we demonstrate a systematic design of a series of new compounds with a 2×2×2 superstructure of the half‐Heusler unit cell in X–Y–Z (X=Fe, Ru, Co, Rh, Ir; Y=Zn, Mn; Z=Sn, Sb) systems. Their structures were solved by using both powder and single‐crystal X‐ray diffraction, and also directly observed by using high‐angle annular dark‐field imaging in a scanning transmission electron microscope (HAADF‐STEM). The VEC values of these new compounds span a wide and continuous range comparable to those for the full‐ and half‐Heusler families, thereby implying tunability in compositions and physical properties in the superstructure. In fact, we observed abnormal electrical properties and a ferromagnetic semiconductor‐like behavior with a high and tunable Curie temperature in these superstructures. 相似文献