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81.
Ayako Tokiwa Masayasu Nagoshi Yasuhiko Syono 《Physica C: Superconductivity and its Applications》1990,170(5-6):437-442
Superconductivity and composition analysis of PbBaSr(Y, Ca)Cu3Oy with fixed ratio of Sr/Ba = 1 were studied. Synthesis condition and superconductivity of Pb(Ba, Sr)2(Y, Ca)Cu3Oy with various ratio of Sr/Ba and Ca/Y were also studied. It was found that Tc increased with increasing Ca concentration, and that Sr-rich specimens allowed to contain more Ca. PbBa0.8Sr1.2Y0.6Ca0.4Cu3O7 showed superconductivity with zero-resistance temperature of 42 K, which was higher than PbBaSrY0.7Ca0.3Cu3O7 with maximum Ca content for Sr/Ba = 1. Decrease in averaged ionic radii of Ba and Sr in Sr-rich compositions would be favorable for the contraction of Cu-O bonds by hole-doping via Ca substitution for Y. 相似文献
82.
A sealed tube dry combustion method that is simple, accurate, and precise for ultramicro determination of halogens in organic compounds has been developed. Samples below 1 mg are heated at 580 °C for 1 h in an electric furnace. After the combustion and absorption of the gaseous halogen, the interior of the tube is rinsed. Subsequent titration is carried out potentiometrically with silver nitrate and yielded standard deviations of 0.21% for chlorine, 0.17% for bromine, and 0.25% for iodine. 相似文献
83.
84.
Michio Zenki Makiko Ideshima Miwa Taniguchi Ayako Katoh Takashi Yokoyama 《Analytical sciences》2005,21(5):517-520
A circulatory flow-injection method (cyclic FIA) for the repetitive determination of zinc has been proposed. The procedure involves the use of 2-(5-bromo-2-pyridylazo)-5-[N-n-propyl-N-(3-sulfopropyl)amino]phenol (5-Br-PAPS) together with EDTA as a reagent carrier solution, which is recycled in a single-line flow system via a reservoir. The formed 5-Br-PAPS-Zn(II) complex was measured spectrophotometrically at 552 nm, and the signal intensity corresponded to the zinc concentration. After passing through a flow-through cell, the carrier stream then returned to the reservoir, and the main reagent, 5-Br-PAPS, was successfully regenerated by a ligand-exchange reaction with EDTA, allowing the repetitive determination of zinc. The calibration curve for zinc was linear in the concentration range from 0.4 to 10.0 mg dm(-3) with a correlation coefficient of 0.9995 (n = 6). The detection limit of this method was 0.02 mg dm(-3) (S/N= 3). This method allowed as many as 300 repetitive determinations of 2.0 mg dm(-3) zinc solution with only 100 cm3 of the circulating carrier solution, providing a reduction in the consumption of reagents and an elimination of waste, an important approach towards clean chemistry. 相似文献
85.
86.
Iron–Oxalato Framework with One‐Dimensional Open Channels for Electrochemical Sodium‐Ion Intercalation
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Dr. Xianfen Wang Ryosuke Kurono Dr. Shin‐ichi Nishimura Dr. Masashi Okubo Prof. Atsuo Yamada 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(3):1096-1101
Discovery of a new class of ion intercalation compounds is highly desirable due to its relevance to various electrochemical devices, such as batteries. Herein, we present a new iron–oxalato open framework, which showed reversible Na+ intercalation/extraction. The hydrothermally synthesized K4Na2[Fe(C2O4)2]3 ? 2 H2O possesses one‐dimensional open channels in the oxalato‐bridged network, providing ion accessibility up to two Na+ per the formula unit. The detailed studies on the structural and electronic states revealed that the framework exhibited a solid solution state almost entirely during Na+ intercalation/extraction associated with the reversible redox of Fe. The present work demonstrates possibilities of the oxalato frameworks as tunable and robust ion intercalation electrode materials for various device applications. 相似文献
87.
Dr. Shinichiro Fuse Ayako Ikebe Kazuya Oosumi Tomoya Karasawa Keisuke Matsumura Dr. Miho Izumikawa Dr. Kohei Johmoto Dr. Hidehiro Uekusa Dr. Kazuo Shin‐ya Prof. Takayuki Doi Prof. Takashi Takahashi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(26):9454-9460
An asymmetric total synthesis of ent‐pyripyropene A was achieved by a convergent synthetic route. We used our originally developed TiIII‐catalyzed radical cyclization to construct an AB‐ring portion that consisted of a trans‐decalin skeleton with five contiguous stereogenic centers. The coupling between the AB‐ring and the DE‐ring portions, and a subsequent C‐ring cyclization, led to the total synthesis of ent‐pyripyropene A. An evaluation of the insecticidal activity of ent‐pyripyropene A against two aphid species revealed that ent‐pyripyropene A was 35–175 times less active than naturally occurring pyripyropene A. This result indicated that the biological target of pyripyropene A recognizes the absolute configuration of pyripyropene A. 相似文献
88.
Elliptical notches in rectangular beams under pure bending are examined photoelastically. Stress-concentration factors due to a single elliptical notch are obtained for wide ranges of 2a/h andd/h, where 2a, d, andh are the width of notch, depth of notch, and depth of beam, respectively. In particular, the geometries of the optimum elliptical notches producing the least stress concentrations are obtained. Almost the whole elliptical boundary of these notches are stressed to the same peak, which indicates that these notches will probably produce the least stress concentrations among all notches, elliptical or nonelliptical. The graphs herein will enable the designers to find the stress-concentration factors of elliptical notches and to pick out the geometry of the optimum notch which will give the least stress concentration for any given values of 2a/h andd/h. Stresses and the stress-concentration factors at the bottom of the beam opposite the notch are also obtained. These stresses, though smaller in magnitude, are of an opposite sign to the peak stress at the notch. For brittle materials, a smaller tensile stress may be more critical than a large compressive stress; therefore, these stress-concentration factors are also given. 相似文献
89.
90.
Takahashi H Wakamatsu S Tabata H Oshitari T Harada A Inoue K Natsugari H 《Organic letters》2011,13(4):760-763
To elucidate the active conformation of indometacin that differentiates between cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2), the stereochemistry around the N-benzoylated indole moiety of indometacin was studied. Resolution of stable atropisomers as representative conformations was found to be possible by restricting rotation about the N-C7' and/or C7'-C1' bond. Only the aR-isomer showed specific inhibition of COX-1, and COX-2 was not inhibited by either atropisomer. 相似文献