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101.
Hirokazu Takaki Kazuaki Kobayashi Masato Shimono Nobuhiko Kobayashi Kenji Hirose 《Journal of Electronic Materials》2017,46(10):5593-5598
The thermoelectric properties of TiN/MgO surface nanostructures have been determined using first-principles calculations based on the nonequilibrium Green’s function (NEGF) method. Through structural modification of the surfaces at the atomistic level, we find that the metallic TiN thin-film layer becomes semiconducting with a small bandgap, which enhances the Seebeck coefficient, while the electrical conductivity remains high at room temperature. Hence, a much larger thermoelectric figure of merit is obtained compared with bulk. These findings indicate the possibility of designing thermoelectric devices with surface nanostructures. 相似文献
102.
Kazuaki Ishii Fujio Mizukami Shu -ichi Niwa Makoto Toba Takami Sato 《Catalysis Letters》1994,30(1-4):297-304
A ruthenium-tin-alumina catalyst, prepared by a combination of kneading and impregnation methods, which we have named the combination method, was able to selectively hydrogenate ethyl phenylacetate to 2-phenylethanol; tin oxide was used as a chloride-free tin source. For this combination catalyst, the optimum atomic ratio for Ru: Sn was found to be 1 4. X-ray diffraction measurements showed the presence of tin particles. It appeared that the number of the tin particles had a large effect on the hydrogenation of C=O groups. However, the catalyst prepared with ruthenium oxide had a low activity, possibly owing to the ruthenium metal or ruthenium-tin alloy, which was formed and which obstructed the reaction. 相似文献
103.
Yuji Shimada Kazuaki Maruyama Masaki Nakamura Suguru Nakayama Akio Sughihara Yoshio Tominaga 《Journal of the American Oil Chemists' Society》1995,72(12):1577-1581
Polyunsaturated fatty acids (PUFA), especially docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), can be concentrated
in glycerides by hydrolyzing tuna oil withGeotrichum candidum lipase, the main components in the resulting oil being triglycerides. The reaction mechanism of this selective hydrolysis
was investigated. Although the lipase acted well on the esters of oleic, linoleic, and α-linolenic acids, it did not affect
the esters of γ-linolenic acid, arachidonic acid, EPA, and DHA as much. The action of PUFA-glycerides was mono-> di- > triglycerides.
Furthermore, the condensation of PUFA-partial glycerides and PUFA occurred even in the presence of a large amount of water,
and the partial glycerides converted to the triglycerides by transacylation. These results suggested that the PUFA-rich triglycerides
were accumulated in the glyceride fraction by the following mechanism: The PUFA-partial glycerides generated by the hydrolysis
were converted to PUFA-triglycerides by condensation and transacylation reactions. As the PUFA-triglycerides formed were the
poor substrates of lipase, they were accumulated in the reaction mixture. 相似文献
104.
For a vertical jet system using various liquids, the shape change of liquid jets discharged from nozzles having different nozzle aspect ratios was evaluated in terms of the surface length lm of the jet flow, and the relation between the change of lm and the gas entrainment behavior was investigated. It was found that the way of changing of lm with varying operating conditions or the liquids corresponded well to that of changing of the gas entrainment rate Qg, that is, the change of lm of the jet before plunging could be closely related to the change of Qg. 相似文献
105.
Masanori Yoshida Yuma Wakura Kazuaki Yamagiwa Akira Ohkawa Shuichi Tezura 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2010,85(7):1017-1022
Liquid‐phase mixing is a common operation, often performed in vessels using mechanically rotating impellers. To enhance axial mixing the vessels are generally equipped with baffles; however, in industries where cleaning the vessel interior is a major concern, i.e. food and pharmaceuticals, and crystallization, where baffles can disturb particle growth, unbaffled vessels are preferred. One method of agitation in unbaffled vessels is an impeller that periodically changes either the direction or rate of rotation: so‐called unsteady rotation. For use in an enhanced agitation vessel, an agitation technology using an unsteady forward–reverse rotating impeller in an unbaffled vessel was investigated. Such unsteady agitation is expected to enhance mixing. However, knowledge of the liquid flows in such an apparatus remains elusive. Thus an aim of this work was to characterize the circulation flow in such a system. Circulation by a disk turbine impeller with six flat blades was studied through examination of tracer particle trajectories. Images showing flow patterns with the forward–reverse rotating impeller resembled those obtained with a unidirectionally rotating impeller in a baffled vessel. The pattern was characterized by a circulation loop whose pathway exits from the impeller rotational region and returns to that region past the wall and bottom of the vessel. Time‐series particle tracking velocimetry (PTV) images obtained during one forward–reverse rotation of the impeller showed that the flow near the vessel wall reduced the periodic fluctuation downstream and that a flow that was almost independent of time was induced near the vessel bottom. For the flow from the bottom to the impeller, unsteadiness was provided by proximity to the impeller. Based on the intensity distribution of the unsteady flow produced by this type of forward–reverse rotating impeller within the vessel, the unsteady flow was shown to have the potential to reach the region near the vessel wall. Copyright © 2010 Society of Chemical Industry 相似文献
106.
The quest for novel solid electrolytes and mixed ionic electronic conductors is leading us to attempt aliovalent cation substitution of new classes of oxides, but in a number of cases such doping gives no or unexpected effects. A general feature of many such systems is that they are ternary or higher oxides in which two cations of different valence are site disordered, facilitated by similar size. Examples comprise TiNb2O7, TiP2O7, ZrP2O7 and Ba3La(PO4)3. Doping intended to create charge compensating mobile point defects may in these cases result only in shifting the ratio of the two disordered cations, as this may have a much lower energy cost. This is accompanied by the precipitation of a phase or domains rich in the expelled cation. Entropy and Gibbs energy changes by doping are calculated and compared for cation disordered and non-disordered systems for illustration. 相似文献
107.
108.
Zyun Siroma Naoko FujiwaraTsutomu Ioroi Shin-ichi YamazakiHiroshi Senoh Kazuaki YasudaKazumi Tanimoto 《Journal of power sources》2007
To measure local phenomena in a PEMFC during a transitional state induced by changing of the feeding gas, a segmented cell was fabricated and the local current and local potential distribution were measured under open-circuit conditions. The anode or cathode was divided into 97 segments of 1.5 mm each. A change in the anode gas from nitrogen or oxygen to hydrogen induced momentary internal currents among the segments. The potential distribution in the electrolyte was observed simultaneously using three quasi-reference electrodes located locally. The results supported the reverse-current decay mechanism, which is known to be a mechanism of cathode degradation. Furthermore, internal currents were observed when the cathode gas was changed from nitrogen to oxygen. While the cathode was not subjected to a harmful potential, a large potential distribution was induced in the anode. 相似文献
109.
Dr. Makoto Hashimoto Dr. Takaaki Taguchi Dr. Kazuki Ishikawa Ryuichiro Mori Akari Hotta Susumu Watari Dr. Kazuaki Katakawa Prof. Dr. Takuya Kumamoto Dr. Susumu Okamoto Prof. Dr. Koji Ichinose 《Chembiochem : a European journal of chemical biology》2020,21(5):623-627
Flavin-dependent monooxygenases are ubiquitous in living systems and are classified into single- or two-component systems. Actinorhodin, produced by Streptomyces coelicolor, is a representative polycyclic polyketide that is hydroxylated through the action of the two-component ActVA-5/ActVB hydroxylase system. These homologous systems are widely distributed in bacteria, but their reaction mechanisms remain unclear. This in vitro investigation has provided chemical proof of two consecutive hydroxylations via hydroxynaphthalene intermediates involved in actinorhodin biosynthesis. The ActVA-5 oxygenase component catalyzed a stepwise dihydroxylation of the substrate, whereas the ActVB flavin reductase not only supplied a reduced cofactor, but also regulated the quinone–hydroquinone interconversion of an intermediate. Our study provides clues for understanding the general biosynthetic mechanisms of highly functionalized aromatic natural products with structural diversity. 相似文献
110.
Takahiro Chiba Kazuaki Takeda Kazuki Takeda Fumiyuki Adachi 《Wireless Personal Communications》2011,58(3):455-468
Multi-user single-carrier multiple-input multiple-output (MU SC-MIMO) multiplexing can increase the uplink capacity of a cellular
system without expanding the signal bandwidth. It is practically important to make clear an extent to which the MU SC-MIMO
multiplexing combined with frequency-domain equalization (FDE) and transmit power control (TPC) can increase the uplink capacity
in the presence of the co-channel interference (CCI). Since the theoretical analysis is quite difficult, we resort to the
computer simulation to investigate the uplink capacity. In this paper, frequency-domain zero-forcing detection (ZFD) and frequency-domain
minimum mean square error detection (MMSED) are considered for MU signal detection. It is shown that ZFD and MMSED provide
almost the same uplink capacity and that an advantage of fast TPC over slow TPC diminishes. As a result, MU SC-MIMO using
computationally efficient ZFD can be used together with slow TPC instead of using MMSED. With 8 receive antennas and slow
TPC, MU SC-MIMO multiplexing using ZFD can achieve about 1.5 times higher uplink capacity than SU SC-SIMO diversity. 相似文献