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61.
Isamu Matsunaga Atsuo Ueda Nagatoshi Fujiwara Tatsuo Sumimoto Kosuke Ichihara 《Lipids》1999,34(8):841-846
We have characterized the gene encoding fatty acid α-hydroxylase, a cytochrome P450 (P450) enzyme, from Sphingomonas paucimobilis. A database homology search indicated that the deduced amino acid sequence of this gene product was 44% identical to that
of the ybdT gene product that is a 48 kDa protein of unknown function from Bacillus subtilis. In this study, we cloned the ybdT gene and characterized this gene product using a recombinant enzyme to clarify function of the ybdT gene product. The carbon monoxide difference spectrum of the recombinant enzyme showed the characteristic one of P450. In
the presence of H2O2, the recombinant ybdT gene product hydroxylated myristic acid to produce β-hydroxyristic acid and α-hydroxymyristic acid which were determined
by high-performance liquid chromatography (HPLC) and gas chromatography-mass spectrometry. The amount of these products increased
with increasing reaction period and amount of H2O2 in the reaction mixture. The amount of β-hydroxyl product was slightly higher than that of α-hydroxyl product at all times
during the reaction. However, no reaction products were detected at any time or at any concentration of H2O2 when heat-inactivated enzyme was used. HPLC analysis with a chiral column showed that the β-hydroxyl product was nearly enantiomerically
pure R-form. These results suggest that this P450 enzyme is involved in a novel biosynthesis of β-hydroxy fatty acid. 相似文献
62.
63.
Andrés Mahecha-Botero Tony BoydAli Gulamhusein John R. Grace C. Jim Lim Yoshinori ShirasakiHideto Kurokawa Isamu Yasuda 《International Journal of Hydrogen Energy》2011,36(17):10727-10736
A fluidized-bed membrane reformer was operated in two independent laboratories to map various operating conditions, to investigate the effects of changing the composition of the natural gas feed stream and to verify earlier experimental trials. Two feed natural gases were tested, containing either 95.5 or 90.1 mol% of methane (3.6 or 9.9 mol% of other gaseous higher hydrocarbons). Experimental tests investigated the influence of total membrane area, reactor pressure, permeate pressure and natural gas feed rates. A permeate-H2-to reactor natural gas feed molar ratio >2.3 was achieved with six two-sided membrane panels under steam reforming conditions and a pressure differential across the membranes of 785 kPa. The total cumulative reforming time reached 395 h, while hydrogen purity exceeded 99.99% during all tests. 相似文献
64.
Hideto Kurokawa Hisataka Yakabe Isamu Yasuda Thijs Peters Rune Bredesen 《International Journal of Hydrogen Energy》2014
The surface adsorption effect of CO on the hydrogen permeability of a 12.5 micron-thick Pd77Ag23 membrane has been evaluated quantitatively under experimental conditions close to the operating conditions of the highly-efficient membrane reformer (MRF) system developed by Tokyo Gas. The permeability of the membrane was measured in the conditions of CO concentration between 1 and 5 vol.% at a temperature and pressure of up to 500 °C and 0.6 MPa, respectively. High feed flow rates and a microchannel module configuration were applied in the flux measurements to ensure that the results are obtained with limited influence of concentration polarization adjacent to the membrane surface and hydrogen depletion along the microchannel length. While the CO inhibition effect was close to negligible at 500 °C, it was significant at lower temperatures. At a feed pressure of 0.2 MPa, the CO inhibition effect was only 0.2% at a CO concentration of 1 vol.% and the effect was 3.6% at a CO concentration of 5 vol.% at 500 °C. The CO inhibition effect were 3.4% for 1 vol.% CO and 14.1% for 5 vol.% CO at 400 °C. Measurements were also carried out at a high feed pressure of 0.6 MPa to evaluate the pressure dependence of the CO inhibition effect. The CO inhibition effect decreased to 0.7% at a CO feed concentration of 5 vol.% at 500 °C. Lower CO inhibition effect were also observed at 450 and 400 °C compared to the data obtained with the feed pressure of 0.2 MPa, while the inhibition levels were almost the same at 350 °C. Though the CO inhibition effect is larger at a lower feed pressure of 0.2 MPa, the effect was only 0.2% at 1 vol.% CO at 500 °C, which is close to the operating conditions of the MRF system. This study quantitatively revealed that the CO inhibition effect on hydrogen flux is extremely small when the membrane is operated at temperatures equal to or higher than 500 °C, even for state-of-the-art thin membranes. The performance of the Tokyo Gas MRF seems thus mainly limited by concentration polarization effects. 相似文献
65.
Kenichiro Sato Masahiro Kameda Takao Yasuhara Takashi Agari Tanefumi Baba Feifei Wang Aiko Shinko Takaaki Wakamori Atsuhiko Toyoshima Hayato Takeuchi Tatsuya Sasaki Susumu Sasada Akihiko Kondo Cesario V. Borlongan Mitsunori Matsumae Isao Date 《International journal of molecular sciences》2013,14(11):21513-21524
The number of diabetes mellitus (DM) patients is increasing, and stroke is deeply associated with DM. Recently, neuroprotective effects of glucagon-like peptide-1 (GLP-1) are reported. In this study, we explored whether liraglutide, a GLP-1 analogue exerts therapeutic effects on a rat stroke model. Wistar rats received occlusion of the middle cerebral artery for 90 min. At one hour after reperfusion, liraglutide or saline was administered intraperitoneally. Modified Bederson’s test was performed at 1 and 24 h and, subsequently, rats were euthanized for histological investigation. Peripheral blood was obtained for measurement of blood glucose level and evaluation of oxidative stress. Brain tissues were collected to evaluate the level of vascular endothelial growth factor (VEGF). The behavioral scores of liraglutide-treated rats were significantly better than those of control rats. Infarct volumes of liraglutide-treated rats at were reduced, compared with those of control rats. The level of derivatives of reactive oxygen metabolite was lower in liraglutide-treated rats. VEGF level of liraglutide-treated rats in the cortex, but not in the striatum significantly increased, compared to that of control rats. In conclusion, this is the first study to demonstrate neuroprotective effects of liraglutide on cerebral ischemia through anti-oxidative effects and VEGF upregulation. 相似文献
66.
Abstract One of the important physical-chemical properties that characterizes the interaction of solid surfaces with gases is the bond energy of the adsorbed species. The determination of the bond energy is usually performed indirectly by measuring the heat of adsorption (or heat of desorption) of the gas [1, 2], In order to define the heat of adsorption, let us consider the chemisorption of a diatomic molecule, X2, onto a site on a uniform solid surface, M. The molecule may adsorb without dissociation to form MX2. M represents the adsorption site where bonding occurs to a cluster of atoms or to a single atom. In this circumstance, the heat of adsorption, ΔHads, is defined as the energy needed to break the MX2 bond: 相似文献
67.
Shoji Asai Takayuki Yamazaki Akira Miyazaki Taikan Suehara Toshio Namba Tomio Kobayashi Haruhiko Saito Takatoshi Idehara Isamu Ogawa S. Sabchevski 《Journal of Infrared, Millimeter and Terahertz Waves》2012,33(7):766-776
Positronium is an ideal system for research on QED, especially in a bound state. A discrepancy (3.9σ) is found recently between measured HFS values and the QED prediction (including up-to O(α
3 log α
− 1), where α is the fine-structure constant.). It might be due to a contribution of unknown new physics or common systematic problems
in all the previous measurements. A new method to measure HFS directly is performed using a high power gyrotron. The transition
from ortho-positronium to para-positronium has been observed with 5 σ CL, which is the first observation of M1 transition in (sub)Terahertz region. New technologies of high power gyrotrons are
developed for precision spectroscopy. 相似文献
68.
Atsuhito Honda Masaki Kawano Masayoshi Ishida Keiji Sato Michiro Komatsubara Isamu Ohyama 《材料科学技术学报》2000,16(2):238-243
1. IntroductionThe total performance of inverter power supplieshas improved drastically as a result of the development of colltrol methods, higher performance in semiconductors, and higher speed, higher integration, andlower cost in integrated circuits, making it possible touse the inverter drive method in a wide range of rotating machinery which requires smaller size and/or variable speed drives. In line with these trends, magneticloss under nonsinusoidal waveform excitation, including lower … 相似文献
69.
Isamu Kobayashi 《Information Systems》1987,12(4):343-352
In classical database theory, relational calculus has long been used in expressing query formulae and integrity constraints. In fact, relational calculus formulae are much easier to deal with than first-order formulae when evaluating queries and validating database updates in the database environment. In deductive databases, however, first-order calculus is preferred because it is convenient when proof procedures are involved. Since both situations should coexist in advanced information systems, it is very desirable to devise a conversion procedure between relational calculus and first-order calculus. In this paper, interpretation of first-order formulae in the database environment is discussed first, then tuple calculus, an extension of relational calculus, is presented. This extension enables us to describe query formulae and general rules necessary in advanced information systems, in particular, dealing with complex objects. Finally, a conversion algorithm from first-order formulae into tuple calculus formulae is presented. Several application issues are also included. 相似文献
70.
A process for base-emitter-collector self-aligned HBTs using a pattern-inversion method is presented. A fabricated HBT has an emitter with a size of 1.5 × 10?m2 realised by employing a dry-etching method. Typical current gain for the fabricated HBT is 26. 相似文献