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排序方式: 共有1475条查询结果,搜索用时 15 毫秒
101.
Hashimoto J.-I. Ikoma N. Murata M. Katsuyama T. 《Quantum Electronics, IEEE Journal of》2000,36(8):971-977
A novel window structure realized by selective N ion implantation and subsequent rapid thermal annealing has been applied to overcome the catastrophic optical damage (COD) of a GaInAs-GaInP laser emitting in the 0.98-μm wavelength region. A kink-free output power up to 220 mW at 25°C was obtained. Laser characteristics including the I-L, far-field pattern, and lasing spectrum were almost the same as those of a conventional nonwindow laser consisting of the same structure except for the window region. In a 50°C, APC-150 mW aging test, the window lasers have operated stably beyond 16 000 h, and no damage has been observed. Under this aging condition, a median lifetime of 280 000 h was obtained from log-normal plotting of aging characteristics. This marked improvement in reliability is due to a remarkable increase of damage tolerance realized by the window structure. In addition, there was minimal change in the characteristic of the window laser during the aging, indicating the absence of serious inner degradation. These results clearly show that our 0.98-μm window laser suppresses both COD failure and inner degradation satisfactorily and can be used in practical applications 相似文献
102.
Inés S. Neira Francisco Guitián Takaaki Taniguchi Tomoaki Watanabe Masahiro Yoshimura 《Journal of Materials Science》2008,43(7):2171-2178
We report an effective method for the synthesis of hydroxyapatite whiskers with sharp faceted hexagonal shape employing a
low temperature (90 °C) hydrothermal route with calcium nitrate tetrahydrate, diammonium phosphate and urea as starting materials.
The key parameters of the synthesis process i.e. duration, temperature cycle of the treatment and starting pH value are carefully
varied and the end products are investigated using powder X-ray diffraction (XRD), Raman-scattering, infrared spectroscopy
(IR), elemental analysis, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), transmission electron
microscopy (TEM), electron diffraction (ED), and high-resolution TEM (HRTEM) in order to find the optimal reaction conditions
that lead to the desired hexagonal morphology of HA whiskers. The results demonstrate that gradual and greater increase in
solution pH during the hydrothermal process favors large quantity of the single-crystalline hydroxyapatite whiskers with well
defined hexagonal morphology. 相似文献
103.
Raynoo Thanan Shinji Oikawa Yusuke Hiraku Shiho Ohnishi Ning Ma Somchai Pinlaor Puangrat Yongvanit Shosuke Kawanishi Mariko Murata 《International journal of molecular sciences》2015,16(1):193-217
Reactive oxygen and nitrogen species have been implicated in diverse pathophysiological conditions, including inflammation, neurodegenerative diseases and cancer. Accumulating evidence indicates that oxidative damage to biomolecules including lipids, proteins and DNA, contributes to these diseases. Previous studies suggest roles of lipid peroxidation and oxysterols in the development of neurodegenerative diseases and inflammation-related cancer. Our recent studies identifying and characterizing carbonylated proteins reveal oxidative damage to heat shock proteins in neurodegenerative disease models and inflammation-related cancer, suggesting dysfunction in their antioxidative properties. In neurodegenerative diseases, DNA damage may not only play a role in the induction of apoptosis, but also may inhibit cellular division via telomere shortening. Immunohistochemical analyses showed co-localization of oxidative/nitrative DNA lesions and stemness markers in the cells of inflammation-related cancers. Here, we review oxidative stress and its significant roles in neurodegenerative diseases and cancer. 相似文献
104.
Liposome‐Based in Vitro Evolution of Aminoacyl‐tRNA Synthetase for Enhanced Pyrrolysine Derivative Incorporation 下载免费PDF全文
Dr. Atsuko Uyeda Dr. Takayoshi Watanabe Dr. Yasuhiko Kato Prof. Hajime Watanabe Prof. Tetsuya Yomo Prof. Takahiro Hohsaka Dr. Tomoaki Matsuura 《Chembiochem : a European journal of chemical biology》2015,16(12):1797-1802
Methanosarcina species pyrrolysyl‐tRNA synthetase (PylRS) attaches Pyl to its cognate amber suppressor tRNA. The introduction of two mutations (Y384F and Y306A) into PylRS was previously shown to generate a mutant, designated LysZ‐RS, that was able to attach N‐benzyloxycarbonyl‐L ‐lysine (LysZ) to its cognate tRNA. Despite the potential of LysZ derivatives, further LysZ‐RS engineering has not been performed; consequently, we aimed to generate LysZ‐RS mutants with improved LysZ incorporation activity through in vitro directed evolution. Using a liposome‐based in vitro compartmentalization (IVC) approach, we screened a randomly mutagenized gene library of LysZ‐RS and obtained a mutant that showed increased LysZ incorporation activity both in vitro and in vivo. The ease and high flexibility of liposome‐based IVC should enable the evolution of not only LysZ‐RS that can attach various LysZ derivatives but also of other enzymes involved in protein translation. 相似文献
105.
Kyoko Kofuji Yuzhou Huang Kazufumi Tsubaki Fumihiko Kokido Kazunori Nishikawa Takashi Isobe Yoshifumi Murata 《Reactive and Functional Polymers》2010,70(10):784-789
A transparent wound dressing sheet was obtained by forming a complex between β-glucan and chitosan (CS). These materials were chosen for their biocompatible, bioabsorbable, and biodegradable properties, and they were expected to promote the therapeutic efficacy of the dressing by increasing the wound healing response. The therapeutic efficacy of the β-glucan–CS complex sheet as a wound dressing was evaluated in wounds created on the dorsal surfaces of mice. β-glucan–CS complex sheets demonstrated therapeutic efficacies comparable or superior to that of Beschitin®W, a commercial wound dressing made from CS. Additionally, the β-glucan–CS complex sheet did not dissolve during the application period, did not adhere to wounds, and was easy to remove. Cumulatively, these results indicate that β-glucan–CS complex sheets are a promising new wound dressing product. 相似文献
106.
Makiyo Nishimura Chieko Fukuda Masatsune Murata Seiichi Homma 《Journal of the science of food and agriculture》2003,83(11):1156-1162
A PCR‐amplified genomic DNA fragment encoding Japanese pear (Pyrus pyrifolia) polyphenol oxidase (PPO) was cloned and sequenced. The DNA appears to encode a 66 kDa precursor protein consisting of a 56 kDa mature protein and a 9.5 kDa N‐terminal transit peptide. The amino acid sequence showed high homology with apple PPO. The PPO mainly existed as a soluble fraction in cells and was limitedly proteolysed, while the mature form (56 kDa) was detected in plastids. Immature fruits showing high browning potential had high PPO activity and a high level of phenolics, while mature fruits showing little browning had high PPO activity but a low level of phenolics. Copyright © 2003 Society of Chemical Industry 相似文献
107.
Antioxidant Effects of Herbal Tea Leaves from Yacon (Smallanthus sonchifolius) on Multiple Free Radical and Reducing Power Assays,Especially on Different Superoxide Anion Radical Generation Systems 下载免费PDF全文
Shintaro Sugahara Yuto Ueda Kumiko Fukuhara Yuki Kamamuta Yasushi Matsuda Tatsuro Murata Yasuhiro Kuroda Kiyotaka Kabata Masateru Ono Keiji Igoshi Shin Yasuda 《Journal of food science》2015,80(11):C2420-C2429
Yacon (Smallanthus sonchifolius), a native Andean plant, has been cultivated as a crop and locally used as a traditional folk medicine for the people suffering from diabetes and digestive/renal disorders. However, the medicinal properties of this plant and its processed foods have not been completely established. This study investigates the potent antioxidative effects of herbal tea leaves from yacon in different free radical models and a ferric reducing model. A hot‐water extract exhibited the highest yield of total polyphenol and scavenging effect on 1,1‐diphenyl‐2‐picryl hydrazyl (DPPH) radical among four extracts prepared with hot water, methanol, ethanol, and ethylacetate. In addition, a higher reducing power of the hot‐water extract was similarly demonstrated among these extracts. Varying concentrations of the hot‐water extract resulted in different scavenging activities in four synthetic free radical models: DPPH radical (EC50 28.1 μg/mL), 2,2′‐azinobis(3‐ethylbenzothiazoline‐6‐sulfonic acid) cation radical (EC50 23.7 μg/mL), galvinoxyl radical (EC50 3.06 μg/mL), and chlorpromazine cation radical (EC50 475 μg/mL). The yacon tea‐leaf extract further demonstrated superoxide anion (O2?) radical scavenging effects in the phenazine methosulfate‐NADH‐nitroblue tetrazolium (EC50 64.5 μg/mL) and xanthine oxidase assay systems (EC50 20.7 μg/mL). Subsequently, incubating human neutrophilic cells in the presence of the tea‐leaf extract could suppress the cellular O2? radical generation (IC50 65.7 μg/mL) in a phorbol 12‐myristate 13‐acetate‐activated cell model. These results support yacon tea leaves may be a good source of natural antioxidants for preventing O2? radical‐mediated disorders. 相似文献
108.
The brown pigment in sautéed onion was characterized by a microbiological procedure (involving microbial decolorization) and a chemical procedure (involving metal-chelating chromatography with a Sepharose 6B column). The suitability of the chemical procedure as a method for classifying brown pigments was also examined.The pigment from sautéed onion was about 40% decolorized by Coriolus versicolor IFO 30340, as were the model pigments caramel and model melanoidin (MM). The phenol-type model pigments (PTMP) were approximately 40-60% decolorized by Paecilomyces canadensis NC-1, but the sautéed-onion pigment, the MM and the caramel were merely 5% decolorized by it. The pigment from sautéed onion was separated into two components by Cu2+, Fe2+, or Zn2+-chelating chromatography, as were caramel and MM; the PTMP was not separated into multiple components by either Cu2+ or Fe2+-chelating chromatography. The results from both methods indicate that the pigment from sautéed onion is similar to MM and caramel but not the phenol-type pigment. 相似文献
109.
110.
Yuta Nabatame Tsuyoshi Matsumoto Yuki Ichige Takashi Komine Ryuji Sugita Masayuki Murata Yasuhiro Hasegawa 《Journal of Electronic Materials》2013,42(7):2172-2177
In this study, we have numerically analyzed the transport properties of Bi-Sb nanowires, taking into account wire boundary scattering. Wire boundary scattering slightly decreased the Seebeck coefficient of Bi-Sb nanowires. This effect is due to the observation that boundary scattering and the mobility ratio of L-point electrons to T-point holes in the nanowires are smaller than those in bulk Bi-Sb because the wire boundary scattering suppresses the mobilities of L-point electrons and heavy holes. The largest Seebeck coefficient for all wire diameters was obtained when the Sb concentration was 5 at.%. The effective mass approached zero near 5 at.% Sb, and the small effective mass led to a large subband shift in each band. Thus, a small effective mass enhances the quantum effect at a fixed wire diameter, even if wire boundary scattering is taken into account. 相似文献