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21.
Shuichi Naito Shigeru Aida Toshiki Kasahara Toshihiro Miyao 《Research on Chemical Intermediates》2006,32(3-4):279-290
In situ infrared spectroscopy was applied to elucidate the reaction mechanism of CO hydrogenation over Pd/CeO2. Instead of direct dissociation of CO, a new reaction pathway is proposed for methane formation, involving geminal dicarbonyl intermediates and (HCO)2(a) intermediates, which may be located on the surface of Pd covered with thin layers of reduced ceria (SMSI effect). Transformation of methane formation sites into methanol formation ones by the oxidation with water vapor formed during the CO?H2 reaction is proposed, which may be located on the Pd (111) planes adjacent to ceria support. 相似文献
22.
T. Kasahara H.S. Park D. Shindo H. Yoshikawa T. Sato K. Kondo 《Journal of magnetism and magnetic materials》2006
Domain wall motion in Mn–Zn and Ni–Zn ferrites with applied magnetic fields is investigated by in situ observations with Lorentz microscopy and electron holography. It is found that both Mn–Zn and Ni–Zn ferrites have a mean grain size of approximately 10 μm and several pores with sizes ranging from 0.2 to 1.1 μm. In situ observations by Lorentz microscopy with an applied magnetic field reveals that in Mn–Zn ferrite, the domain walls move easily across the grain boundary, while in Ni–Zn ferrite, the domain walls move along the grain boundary but are pinned at the grain boundary and pores. From in situ observations of Ni–Zn ferrite by electron holography, it is clarified that domain wall pinning at the grain boundary retards a sensitive increase in magnetic flux parallel to the applied field direction, which is considered to result in high hysteresis loss. 相似文献
23.
A micro-phase sorbent in situ formation from an aqueous solution was proposed for the sensitive spectrophotometric determination of nitrite in environmental waters. Nitrite in a 10 mL sample solution was converted into a cationic azo dye by the reaction with 4-trifluoromethylanilinium ion and N-1-naphthylethylenediammonium ion in an acidic medium. Addition of dodecylbenzenesulfonate ion caused the formation of a suspension of ion associate in the solution. Centrifugation of the solution led to the isolation of a liquid organic phase that extracted the azo dye at the bottom of the centrifuge tube. The volume of the new phase was ca. 5 microL. After the aqueous phase was discarded, the organic phase was dissolved with 1 mL of 2-methoxyethanol to measure the absorbance. Nitrogen as NO2- at concentrations from 1.5 to 30 microg L(-1) was determined with sufficient precision. When 0.2 mL of 2-methoxyethanol was applied to dissolve the organic phase, 0.3-4.8 microg NO2--N L(-1) was determined. The recovery tests for nitrite added to some river water and seawater were satisfactory. This method is very simple and rapid. It takes only 30 min from the dye formation to the measurement of the absorbance. 相似文献
24.
Tsutomu Nakanishi Hajime Okamoto Maki Kasahara Kyozaburo Takeda 《Journal of Polymer Science.Polymer Physics》2003,41(22):2829-2849
We theoretically investigated the polymorphy of the stereostructures of a periodic polymer. Using the polymer's internal conformation parameters of bond lengths, bond angles, and internal rotation angles, we extended the mathematical treatment for designing polymer backbones. We considered those periodic polymers whose unit cell consists of one (m = 1), two (m = 2), or three (m = 3) kinds of atoms. Moreover, for these three types of polymers, we supposed two catenation types for the skeleton atoms; one is a “homorotatory” sequence and the other is a “heterorotatory” one. To specify the backbone's stereostructure, we introduced several conformation parameters such as the helical pitch number n, the translation distance d, and the inclination angle of the skeleton plane Θ. By combining these parameters, we can systematically understand the variety and the possible polymorphy in the stereostructure of a periodic polymer backbone. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 2829–2849, 2003 相似文献
25.
Shoji Kasahara Tetsuya Takine Yutaka Takahashi Toshiharu Hasegawa 《Queueing Systems》1993,14(3-4):349-367
Many researchers have studied variants of queueing systems with vacations. Most of them have dealt with M/G/1 systems and have explicitly analyzed some of their performance measures, such as queue length, waiting time, and so on. Recently, studies on queueing systems whose arrival processes are not Poissonian have appeared. We consider a single server queueing system with multiple vacations and E-limited service discipline, where messages arrive to the system according to a switched Poisson process. First, we consider the joint probability density functions of the queue length and the elapsed service time or the elapsed vacation time. We derive the equations for these pdf's, which include a finite number of unknown values. Using Rouché's theorem, we determine the values from boundary conditions. Finally, we derive the transform of the stationary queue length distribution explicitly. 相似文献
26.
Both abilities of germination of spores formed after UV irradiation and of growth of amoeboid cells emerged from the spores were studied on two kinds of Dictyostelium discoideum strains, NC-4 and ys-13.
An inhibition of germination was observed on the spores of ys -13 when formed after UV irradiation, while no inhibition was detected on the ability of germination of spores of NC-4. The amoeboid cells of ys -13 emerged from the spores showed a heavy delay of growth, although no delay of growth was detected even on the amoeboid cells of NC-4 emerged from the spores formed after UV irradiation. The strain of NC-4 must repair UV lesions fully before spore formation, while the spores of ys-13 must keep some UV lesions unrepaired and send them to the next generation of amoeboid cells. The characters of UV lesion inheritable through the spores to the next amoeboid cells in ys-13 were discussed. 相似文献
An inhibition of germination was observed on the spores of ys -13 when formed after UV irradiation, while no inhibition was detected on the ability of germination of spores of NC-4. The amoeboid cells of ys -13 emerged from the spores showed a heavy delay of growth, although no delay of growth was detected even on the amoeboid cells of NC-4 emerged from the spores formed after UV irradiation. The strain of NC-4 must repair UV lesions fully before spore formation, while the spores of ys-13 must keep some UV lesions unrepaired and send them to the next generation of amoeboid cells. The characters of UV lesion inheritable through the spores to the next amoeboid cells in ys-13 were discussed. 相似文献
27.
A Kasahara T Onodera M Mogi Y Oshima M Shimizu 《Chemical & pharmaceutical bulletin》1965,13(12):1460-1469
28.
Kasahara Y Iwasawa T Shimizu Y Shishido H Shibauchi T Vekhter I Matsuda Y 《Physical review letters》2008,100(20):207003
The phase diagram of the quasi-2D Ce(Ir,Rh)In5 system contains two distinct superconducting domes. By the thermal transport measurements in rotating magnetic fields H, we pinned down the superconducting gap structure of CeIrIn5 in the second dome, located distant from the first dome in proximity to an antiferromagnetic quantum critical point. Clear fourfold oscillation was observed when H is rotated within the ab plane, while no oscillation was observed within the bc plane. In sharp contrast to previous reports, our results are most consistent with dx2-y2 symmetry, implying that the superconductivity in the second phase is also mediated by antiferromagnetic spin fluctuations. 相似文献
29.
Bis[2-(5-chloro-2-pyridylazo)-5-diethylaminophenolato]cobalt(III) is proposed for the extraction and spectrophotometric determination of sulphated and sulphonated surfactants. The complex and the surfactants form ion-pairs which are extracted into benzene from O.1M hydrochloric acid. The absorbance of the benzene phase is measured at 560 nm against a reagent blank. Less than 25 mug of sodium di-(2-ethylhexyl) sulphosuccinate in 50-200 ml of sample solution is determined reproducibly by the proposed method. When applied to river water samples, the proposed method gives results which agree very well with those obtained by the standard Methylene Blue method. However, the proposed method is simpler and more sensitive than the Methylene Blue method. 相似文献
30.
Mohsen Pourahmadi Akihiko Inoue Yukio Kasahara 《Proceedings of the American Mathematical Society》2007,135(4):1233-1239
For a nonnegative integrable weight function on the unit circle , we provide an expression for , in terms of the series coefficients of the outer function of , for the weighted distance , where is the normalized Lebesgue measure and ranges over trigonometric polynomials with frequencies in , , . The problem is open for .