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991.
Discovery of Natural Products Possessing Selective Eukaryotic Readthrough Activity: 3‐epi‐Deoxynegamycin and Its Leucine Adduct
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Dr. Akihiro Taguchi Keisuke Hamada Masaya Kotake Dr. Masataka Shiozuka Dr. Hidemasa Nakaminami Dr. Thanigaimalai Pillaiyar Dr. Kentaro Takayama Dr. Fumika Yakushiji Prof. Norihisa Noguchi Prof. Takeo Usui Prof. Ryoichi Matsuda Prof. Yoshio Hayashi 《ChemMedChem》2014,9(10):2233-2237
Herein we report the first discovery of natural readthrough products that do not display antimicrobial activity. Two natural negamycins, 3‐epi‐deoxynegamycin and its leucine adduct, isolated 37 years ago, were found to be potent readthrough agents against nonsense mutations of eukaryotes, but not prokaryotes, without displaying antimicrobial activity. These results suggest that the compounds are valuable leads for the development of readthrough drugs against nonsense‐mediated genetic diseases without the potential for contributing to the emergence of drug‐resistant bacteria. 相似文献
992.
Takeo Kimura Tomohisa Miyazawa Jin Nishikawa Shigeru Kado Kazu Okumura Toshihiro Miyao Shuichi Naito Kimio Kunimori Keiichi Tomishige 《Applied catalysis. B, Environmental》2006,68(3-4):160-170
Catalytic performance of Ni/CeO2/Al2O3 catalysts prepared by a co-impregnation and a sequential impregnation method in steam gasification of real biomass (cedar wood) was investigated. Especially, Ni/CeO2/Al2O3 catalysts prepared by the co-impregnation method exhibited higher performance than Ni/Al2O3 and Ni/CeO2/Al2O3 prepared by the sequential impregnation method, and the catalysts gave lower yields of coke and tar, and higher yields of gaseous products. The Ni/CeO2/Al2O3 catalysts were characterized by thermogravimetric analysis, temperature-programmed reduction with H2, transmission electron microscopy and extended X-ray absorption fine structure, and the results suggested that the interaction between Ni and CeO2 became stronger by the co-impregnation method than that by sequential method. Judging from both results of catalytic performance and catalyst characterization, it is found that the intimate interaction between Ni and CeO2 can play very important role on the steam gasification of biomass. 相似文献
993.
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995.
Jun-ichi Takahashi Hiroyuki Shinojima Michiko Seyama Yuko Ueno Takeo Kaneko Kensei Kobayashi Hajime Mita Mashahiro Adachi Masahito Hosaka Masahiro Katoh 《International journal of molecular sciences》2009,10(7):3044-3064
One of the most attractive hypothesis for the origin of homochirality in terrestrial bioorganic compounds is that a kind of “chiral impulse” as an asymmetric excitation source induced asymmetric reactions on the surfaces of such materials such as meteorites or interstellar dusts prior to the existence of terrestrial life (Cosmic Scenario). To experimentally introduce chiral structure into racemic films of amino acids (alanine, phenylalanine, isovaline, etc.), we irradiated them with linearly polarized light (LPL) from synchrotron radiation and circularly polarized light (CPL) from a free electron laser. After the irradiation, we evaluated optical anisotropy by measuring the circular dichroism (CD) spectra and verified that new Cotton peaks appeared at almost the same peak position as those of the corresponding non-racemic amino acid films. With LPL irradiation, two-dimensional anisotropic structure expressed as linear dichroism and/or linear birefringence was introduced into the racemic films. With CPL irradiation, the signs of the Cotton peaks exhibit symmetrical structure corresponding to the direction of CPL rotation. This indicates that some kinds of chiral structure were introduced into the racemic film. The CD spectra after CPL irradiation suggest the chiral structure should be derived from not only preferential photolysis but also from photolysis-induced molecular structural change. These results suggest that circularly polarized light sources in space could be associated with the origin of terrestrial homochirality; that is, they would be effective asymmetric exciting sources introducing chiral structures into bio-organic molecules or complex organic compounds. 相似文献
996.
Atsushi Satsuma Hajime Maeshima Kiyoshi Watanabe Kenji Suzuki Tadashi Hattori 《Catalysis Today》2000,63(2-4):347-353
Catalytic activities of various metal oxides for decomposition of nitrous oxide were compared in the presence and absence of methane and oxygen, and the general rule in the effects of the coexisting gases was discussed. The reaction rates of nitrous oxide were well correlated to the heat of formation of metal oxide, i.e., a V-shaped relationship with a minimum at −ΔHf0 around 450 kJ (O mol)−1 was observed in N2O decomposition in an inert gas. In the case of metal oxides having the heat of formation lower than 450 kJ (O mol)−1, CuO, Co3O4, NiO, Fe2O3, SnO2, In2O3, Cr2O3, the activities were strongly affected by the presence of methane and oxygen. On the other hand, the activities of TiO2, Al2O3, La2O3, MgO and CaO were almost independent. The reaction rate of nitrous oxide was significantly enhanced by methane. The promotion effect of methane was attributed to the reduction of nitrous oxide with methane: 4N2O+CH4→2N2+CO2+2H2O. The activity was suppressed in the presence of oxygen on the metal oxides having lower heat of formation. On the basis of Langmuir–Hinshelwood mechanism, the effect of oxygen on nitrous oxide decomposition was rationalized with the strength of metal–oxygen bond. 相似文献
997.
J. Song K. Kakushima P. Ahmet K. Tsutsui N. Sugii T. Hattori H. Iwai 《Microelectronic Engineering》2009,86(7-9):1638-1641
The study on post metallization annealing (PMA) in electrical characteristics and interfacial properties of La2O3/Ge structures has been conducted. The PMA treatment in N2 ambient induces the growth of interfacial Ge oxide layer accompanied with decrease of capacitance value and interface trap density. The interface-layer growth is caused by the oxidation of Ge substrate due to the hydroxyl group absorbed in La2O3 from the ambient. The metal electrode capping might prevent the hydroxyl from evaporating during annealing, which enhances the interface reaction. On the other hand, leakage current increment has been observed for the sample with PMA in case of using Pt gate electrode. It is due to the diffusion of Pt and/or Ge and a Pt-germanide formation in La2O3 film during PMA. This leakage current increment can be suppressed by using Ta or W electrode which has less reactivity with Ge than Pt at high temperature. 相似文献
998.
Yasuo Hikichi Toshitaka Ota Keiji Daimon Tomotoshi Hattori Masatoshi Mizuno 《Journal of the American Ceramic Society》1998,81(8):2216-2218
Xenotime-type RPO4 (R = Y, Er, Yb, or Lu) powder was dry-pressed into disks and bars. The disks and bars could be sintered to a relative density of greaterthan equal to98% in air without cracking at 1300° (R = Yb or Lu) or 1500°C (R = Y or Er), depending on the grain size. The linear thermal expansion coefficient (at 1000°C), thermal conductivity (at 20°C), and bending strength (at 20°C) of the xenotime-type RPO4 ceramics were 6.2 10-6 /°C, 12.02 W(mK)-1 , and 95 ± 29 MPa for R = Y; 6.0 10-6 /°C, 12.01 W(mK)-1 , and 100 ± 21 MPa for R = Er; 6.0 10-6 /°C, 11.71 W(mK)-1 , and 135 ± 34 MPa for R = Yb; and 6.2 10-6 /°C, 11.97 W(mK)-1 , and 155 ± 25 MPa for R = Lu. The xenotime-type RPO4 ceramics did not react with SiO2 , TiO2 , Al2 O3 , ZrO2 , or ZrSiO4 , even at 1600°C for 3 h in air, and were stable in aqueous solutions of HCl, H2 SO4 , HNO3 , NaOH, and NH4 OH at 20°C. 相似文献
999.
T. Hattori H. Nohira S. Shinagawa M. Hori M. Kase T. Maruizumi 《Microelectronics Reliability》2007,47(1):20-26
This work reviews the study of the chemical composition and the chemical structure of ultrathin oxynitride films using angle-resolved photoelectron spectroscopy. The nearest and the second nearest neighbors of a nitrogen atom in oxynitride films were determined from the deconvolution of N 1s spectra. It was found by applying maximum entropy concept to the angle resolved Si 2p and N 1s photoelectron spectra that the distribution of nitrogen atoms and their bonding configurations in oxynitride films formed by the plasma nitridation is quite different from those in oxynitride films formed by the interface nitridation. 相似文献
1000.
Aboubakr M. Abdullah Ahmad M. Mohammad Takeyoshi Okajima Fusao Kitamura Takeo Ohsaka 《Journal of power sources》2009,190(2):264-270
The effect of the operating conditions, e.g., load, temperature, relative humidity (RH), and the MEA's aging condition on the pH of the water drained out from the cathode and anode sides of a H2/air PEM fuel cell was studied. Also the effect of the pollutants’ existence in natural air on the measured pH and the performance of the fuel cell was investigated. pH values as low as 1 were measured for the water drained out from the cathode side under a low temperature–low RH condition. Increasing the load, temperature or RH value resulted in an increase of the measured pH except for the low temperature–low RH condition where increasing the load resulted in a decrease in the measured pH. On the other hand, the pH value of the water drained out from the anode side was around 4 under the same low temperature–low RH condition. Aging of the MEA at 90 °C and RH of 100% for at least 30 h resulted in low measured pH values for the water drained out from the cathode side. The polarization behaviors of the cathode under these different conditions were measured and correlated to the pH change and the performance of the MEA. Measuring the pH using a flow pH meter for the water droplets drained out from the cathode side can be used as an alarm for the onset of the chemical degradation of the Nafion membrane. 相似文献