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61.
Dr. Ryota Hidese Dr. Kenichi Ataka Dr. Eckhard Bill Dr. Seigo Shima 《Chembiochem : a European journal of chemical biology》2015,16(13):1861-1865
[Fe]‐Hydrogenase (Hmd) catalyzes reversible hydride transfer from H2. It harbors an iron‐guanylylpyridinol as a cofactor with an FeII that is ligated to one thiolate, two COs, one acyl‐C, one pyridinol‐N, and solvent. Here, we report that CuI and H2O2 inactivate Hmd (half‐maximal rates at 1 μM CuI and 20 μM H2O2) and that FeII inhibits the enzyme with very high affinity (Ki=40 nM ). Infrared and EPR studies together with competitive inhibition studies with isocyanide indicated that CuI exerts its inhibitory effect most probably by binding to the active site iron‐thiolate ligand. Using the same methods, it was found that H2O2 binds to the active‐site iron at the solvent‐binding site and oxidizes FeII to FeIII. Also it was shown that FeII reversibly binds away from the active site iron, with binding being competitive to the organic hydride acceptor; this inhibition is specific for FeII and is reminiscent of that for the [FeFe]‐hydrogenase second iron, which specifically interacts with H2. 相似文献
62.
Dr. Naoki Umezawa Yuhei Horai Dr. Yuki Imamura Makoto Kawakubo Mariko Nakahira Dr. Nobuki Kato Akira Muramatsu Prof. Dr. Yuko Yoshikawa Prof. Dr. Kenichi Yoshikawa Prof. Dr. Tsunehiko Higuchi 《Chembiochem : a European journal of chemical biology》2015,16(12):1811-1819
A versatile solid‐phase approach based on peptide chemistry was used to construct four classes of structurally diverse polyamines with modified backbones: linear, partially constrained, branched, and cyclic. Their effects on DNA duplex stability and structure were examined. The polyamines showed distinct activities, thus highlighting the importance of polyamine backbone structure. Interestingly, the rank order of polyamine ability for DNA compaction was different to that for their effects on circular dichroism and melting temperature, thus indicating that these polyamines have distinct effects on secondary and higher‐order structures of DNA. 相似文献
63.
We report the latest advances in understanding, characterization and modeling of key micro mechanisms and origins underpinning the interesting and complex macroscopic behavior of granular matter. Included in this Topical Collection are novel theories, innovative experimental tools and new numerical approaches, focusing primarily on three subtopics governing important multiscale properties of granular media: (a) the jamming transition from fluid- to solid-like behavior, critical state flow and wave propagation, (b) the signature of fabric and its evolution for granular media under general loading conditions, and (c) mechanisms like rotation, breakage, failure and aggregation. The significance of these contributions and exploratory future directions pertaining to cross-scale understanding of granular matter are discussed. 相似文献
64.
65.
Kazuo Matsuda Kenichi Kawazuishi Yoshiichi Hirochi Rei Sato Yasuki Kansha Chihiro Fushimi Yutaka Shikatani Hiroshi Kunikiyo Atsushi Tsutsumi 《Applied Thermal Engineering》2010,30(16):2300-2305
The reaction section of the naphtha hydro-desulfurization (HDS) process is a heating and cooling thermal process consisting of a feed/effluent heat exchanger and a fired heater. Energy savings are fundamentally made as a result of the maximized heat recovery in the heat exchanger and the reduced heat duty of the fired heater. To achieve further energy saving in the process, “self-heat recuperation technology” (SHRT) was adopted. In this technology, a compressor was introduced. The suction side of the compressor needed a lower pressure and the feed stream evaporated much easily. The discharged side of the compressor satisfied the operating conditions of both pressure and temperature at the inlet of the reactor. And the reactor effluent stream was able to be used completely to preheat and vaporize the feed stream. All the heat in the process stream was re-circulated without using a fired heater. SHRT was applied to the naphtha HDS process of 18,000 barrel per stream day (BPSD) in the refinery and the mass and energy balance of the process was calculated using commercially available simulation software, Invensys PROII version 8.1. This process-simulation case study confirmed that despite there being no more energy saving potential in the conventional process that makes use of a fired heater, the advanced process with SHRT can reduce the energy consumption significantly by using the recuperated heat of the feed stream. 相似文献
66.
The stress field around a propagating crack tip in a quenched thin glass plate is discussed through experimental and theoretical analyses. Instantaneous phase-stepping photoelasticity using a CCD camera equipped with a pixelated micro-retarder array is used for measuring the crack tip stress field. From the successive phase maps of principal direction, the position and the velocity of the crack tip are evaluated. On the other hand, the fracture parameters, that is, the stress intensity factors and the T-stress are determined from the phase maps of the retardation. Experimental results obtained for a straight crack show good agreement with those obtained by theory of elasticity. The results also indicate that the direction of the crack propagation arising in the quenching process is not determined by the direction of the maximum principal stress. Furthermore, the results show that the T-stress criterion is inappropriate to evaluate the crack path instability in a quenched thin glass plate. 相似文献
67.
Teruhiro Kasagi Takanori Tsutaoka Kenichi Hatakeyama 《Journal of the European Ceramic Society》2010,30(2):401-406
Dielectric and electrical properties of Permalloy granular composite materials have been studied considering the application to left-handed meta-materials. Surface oxidized Permalloy particles have high surface electrical resistance; the eddy current effect in the composite structure is suppressed. The electrical conductivity of compacted Permalloy particles increases with increasing temperature and indicates the semiconductive layer formation on the particle. The low frequency ac electrical conductivity of Permalloy composite materials shows a drastic increase in the particle content between 50 and 60 vol.%. Electrical permittivity spectra of Permalloy composites show a non-metallic characteristic and the enhancement of permittivity is observed with increase of Permalloy particle content. 相似文献
68.
Dongchul Kang Mari Hakamatsuka Kenichi Kojima Masaru Tachibana 《Diamond and Related Materials》2010,19(5-6):578-580
Fine structure of the Raman D band in single-wall carbon nanotubes (SWNTs) was investigated by heating and laser irradiation. It is shown that the D band is composed of three components at ~ 1313, 1340, and 1355 cm? 1, denoted by D1, D2, and D3, respectively. The D1 and D2 intensities significantly increase with laser irradiation in air and vacuum, respectively. The D3 intensity drastically increases with heating in air. From these results, it is suggested that the fine structure of the D band is attributed to different kinds of defects introduced in SWNTs. 相似文献
69.
Kenichi Ohsasa 《Journal of Phase Equilibria and Diffusion》2001,22(4):498-503
Solidification simulation of an aluminum-base multicomponent alloy was carried out by a method combining thermodynamic analysis
using Thermo-Calc and heat-transfer calculation. An Al-9.5% Si-3% Cu-1% Mg-0.8% Fe (all mass%) aluminum-base multicomponent
alloy was used for the simulation. The effect of latent heat on the heat-transfer calculation was considered by using an enthalpy
method. The temperature-enthalpy curves for both an equilibrium state and nonequilibrium state with assumptions of no diffusion
in the solid were calculated by using Thermo-Calc. A small casting with a cylindrical shape was used for the heat-transfer
simulation. The vertical cross section of the casting was divided into rectangular grids, and the enthalpy change of each
grid was numerically calculated. The calculated enthalpies in the grids were converted for each time-step into temperatures
by using the temperature-enthalpy curve. A casting experiment was carried out under the same conditions as those of the simulation,
and the calculated cooling curves obtained under the nonequilibrium condition agreed with the experimental ones. 相似文献
70.
Shunji Yunoki Toshiyuki Ikoma Akira Monkawa Kazushi Ohta Junzo Tanaka Shinichi Sotome Kenichi Shinomiya 《Journal of the American Ceramic Society》2006,89(9):2977-2979
Gamma irradiation treatment (GIT) is the most widely used sterilization method for biomaterials in spite of the potential to degrade polymers. The adverse effects of GIT on the mechanical properties and biological stabilities of porous hydroxyapatite/collagen (HAp/Col) composites were investigated in this study. Those properties of a porous HAp/Col composite stabilized by dehydrothermal treatment (DHT) drastically decreased by GIT in the same manner as conventional pure Col materials. DHT after GIT could partially eliminate the adverse effects, due to the introduction of cross-linkage among the degraded Col molecules. 相似文献