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41.
The effect of the Rh addition to the well defined cubic (≈70%) Pt nanocrystals of around 13 nm supported on alumina was investigated
for NO/CH4 reaction. The impact of size and shape of Pt nanoparticles on the catalytic activity were also analyzed by comparing the
results with a conventionally prepared catalyst. 相似文献
42.
Self‐Activated Vanadate Compounds Toward Realization of Rare‐Earth‐Free Full‐Color Phosphors 下载免费PDF全文
Yuta Matsushima Takuhiro Koide Masahiro Hiro‐Oka Minori Shida Akane Sato Sho Sugiyama Michimasa Ito 《Journal of the American Ceramic Society》2015,98(4):1236-1244
Rare‐earth‐free phosphors based on vanadate compounds were investigated, where the vanadates included chloride vanadates (MII2VO4Cl), pyrovanadates (MII2V2O7), orthovanadates (MII3(VO4)2) with divalent cations MII of Mg, Sr, Ba, and Zn, and oxofluorovanadates (AIVOF4) with an alkali metal AI. A chloride pyrolysis method and a liquid phase precipitation method were proposed for preparing the chloride vanadates and pyro‐ and orthovanadates, respectively. These vanadate compounds showed self‐activated photoluminescence (PL) based on the VO4 clusters against the ultraviolet (UV) light irradiation. The colors of PL covered almost the whole visible‐light region from blue to yellow as Sr2VO4Cl (deep blue), Ca2VO4Cl (sky blue), Ba2V2O7 (green), Sr2V2O7 (yellowish green), Zn3(VO4)2 (yellow), and Mg3(VO4)2 (yellow). A correlation was suggested from these compounds between the luminescent colors and the structural feature as the longer V–O distances in the VO4 tetrahedra in the crystal structures led to the longer wavelength in PL. This seemed to be also applicable for the oxofluorovanadates AIVOF4 (AI = K and Cs) which contain the VOF4 polyhedra with one O2? ion and four F‐ ions as the ligands, as they exhibited the reddish PL. 相似文献
43.
Metformin Protects against NMDA-Induced Retinal Injury through the MEK/ERK Signaling Pathway in Rats
Koki Watanabe Daiki Asano Hiroko Ushikubo Akane Morita Asami Mori Kenji Sakamoto Kunio Ishii Tsutomu Nakahara 《International journal of molecular sciences》2021,22(9)
Metformin, an anti-hyperglycemic drug of the biguanide class, exerts positive effects in several non-diabetes-related diseases. In this study, we aimed to examine the protective effects of metformin against N-methyl-D-aspartic acid (NMDA)-induced excitotoxic retinal damage in rats and determine the mechanisms of its protective effects. Male Sprague–Dawley rats (7 to 9 weeks old) were used in this study. Following intravitreal injection of NMDA (200 nmol/eye), the number of neuronal cells in the ganglion cell layer and parvalbumin-positive amacrine cells decreased, whereas the number of CD45-positive leukocytes and Iba1-positive microglia increased. Metformin attenuated these NMDA-induced responses. The neuroprotective effect of metformin was abolished by compound C, an inhibitor of AMP-activated protein kinase (AMPK). The AMPK activator, AICAR, exerted a neuroprotective effect in NMDA-induced retinal injury. The MEK1/2 inhibitor, U0126, reduced the neuroprotective effect of metformin. These results suggest that metformin protects against NMDA-induced retinal neurotoxicity through activation of the AMPK and MEK/extracellular signal-regulated kinase (ERK) signaling pathways. This neuroprotective effect could be partially attributable to the inhibitory effects on inflammatory responses. 相似文献
44.
Akane Kitamura Tomohiro KobayashiAkihiro Suzuki Takayuki Terai 《Surface & coatings technology》2011,206(5):841-844
Tissue reconstruction is the aim of regeneration medicine and tissue engineering. One of the techniques is cell sheet engineering, which requires creating a contiguous cell sheet and harvesting it safely. To create a favorable substrate for cultivation, we attempted to fabricate the microstructure at polytetrafluoroethylene (PTFE) surfaces using ion beam irradiation. PTFE is a typical fluoropolymer and it possesses chemical and bioinertness. When the surface is irradiated with an ion beam, it is covered with a large number of microprotrusions, which have an aspect ratio of about 100. We previously reported that fibroblast cells grow and spread between the tops of the protrusions. In this study, we fabricated fine protrusions at both the PTFE and the poly(tetrafluoroethylene-co-hexafluoropropylene) (FEP) surfaces. The composition of FEP and PTFE is similar but FEP melts at a lower temperature than PTFE does. These samples were irradiated under controlled temperature and rubbing preparation. Their surface morphology and chemical bonding were observed. When the PTFE surface was irradiated at 350 °C, the protrusions were formed at the lower fluence, with an improved uniformity of shape. This was because the morphological change and evaporation of the thin parts were enhanced during high-temperature irradiation. In the FEP sample, very fine protrusions formed at much lower fluence by irradiation at room temperature. On the surface, the cells spread closely, like a monolayer. Further, the FEP samples were still optically transparent after the irradiation. They have an advantage in that we can observe the living cells attaching to the surface in their natural state without them being killed, fixed, and stained in an optical microscope. We found that the irradiated FEP surface is suitable for making a cell sheet. 相似文献
45.
46.
Summary: More than twenty years have passed since we invented PCN, in which only a few wt.‐% of silicate is randomly and homogeneously dispersed in the polymer matrix. When molded, these nanocomposites show superior properties compared to those of pristine polymers. The number of papers on PCN has increased rapidly in recent years, reaching over 500 in 2005 alone. Being pioneers of this new technology, we review its history relative to the following epochal events:
- In 1985 we invented nylon 6‐clay hybrid (NCH), the first PCN.
- In 1989, cars equipped with a NCH part were launched.
- In 1997, Gilman found revolutionary fire retardancy in NCH.
- In 1997, a PP‐clay nanocomposite was prepared using a compatibilizer.
- In 1998, a compounding method for producing PCN was completed.
- In 2002, Haraguchi invented a revolutionary nanocomposite hydrogel.
47.
48.
Hofstetter TB Neumann A Arnold WA Hartenbach AE Bolotin J Cramer CJ Schwarzenbach RP 《Environmental science & technology》2008,42(6):1997-2003
Compound-specific analysis of nitrogen isotope fractionation is an important tool for assessing transformation pathways of N-containing organic contaminants. We investigated 15N-fractionation during the abiotic reduction of a series of nitroaromatic compounds (NACs) with intrinsic reactivities covering almost 6 orders of magnitude to evaluate substituent effects on 15N kinetic isotope effects, KIEN. Insights into reaction mechanisms and isotopic elementary reactions of NAC reduction were obtained from comparison of experimental results to density-functional theory (DFT) calculations of intrinsic KIEN. Apparent KIEN values for reduction of NACs by structural Fe(II) in octahedral layers of an iron-rich clay mineral were substantial (average +la of 1.038 +/- 0.003), independent of the NACs' reactivity and ring substituent, and larger than reported previously for reduction by Fe(II) species bound to Fe(III)(oxy)hydroxides and mercaptojuglone species (1.031 +/- 0.002). DFT-calculations accounting for semiclassical contributions and quantum-mechanical tunneling yielded a KIEN for N-O bond cleavage between 1.031 and 1.041, showed no substituent effect, and thus agreed well with experimental observations. Calculated transition-state structures of NAC reduction intermediates were consistent with H2O elimination from substituted N,N-dihydroxyanilines as the predominant 15N-fractionating elementary reaction. The absence of substituent effects on the apparent KIEN of NAC reduction may simplify the practical application of 15N-fractionation data for the quantification of contaminant transformation in the environment. 相似文献
49.
Akane Tribidasari A. Akihide Satoshi Mikito Koichi Akira Yasuaki 《Sensors and actuators. B, Chemical》2007,120(2):500-507
Direct detection of sodium azide was examined by using highly boron-doped diamond (BDD) electrodes in some physiological saline buffer solutions. Three important saline buffers, ADA buffer (N-(2-acetamido) iminodiacetic acid), sodium EDTA and imidazole, were investigated. Hydrogen-terminated BDD was fixed for the investigation since it showed much better sensitivity for azide oxidation in comparison with the oxygen-terminated one. Wide range of buffer concentration was examined. A well-separated peak of sodium azide was observed in its mixture with the buffers, resulting in selective sodium azide detection. The current responses were exactly total addition of sodium azide and buffer current responses. The present method was evidenced to be available for direct detection of sodium azide in two samples of commercial diluents for cell counting. A standard addition method was applied. Sodium azide concentrations of 502 and 1355 μg mL−1 were detected in both samples with the R.S.D.s of 0.07 and 2.37%, respectively. Validation was achieved by the comparison with the sample concentrations given by the manufacturer. Simple, selective, good sensitivity and excellent reproducible detection make the diamond electrodes very attractive for numerous electroanalytical applications. 相似文献
50.
Kojima S Iwahara A Hisano Y Yanai H 《Protein engineering, design & selection : PEDS》2007,20(5):211-217
We previously demonstrated that Pleurotus ostreatus proteinase A inhibitor 1 (POIA1) could function as an intramolecular chaperone of subtilisin BPN', as in the case of the propeptide of subtilisin BPN', and that its Phe44 --> Ala mutant, which lost its tertiary structure, could not assist the refolding of subtilisin BPN'. In this study, we examined the effects of hydrophobic amino acid substitutions at other sites and substitutions of Phe44 with other hydrophobic residues on the structure and functions of POIA1. These mutations were introduced into POIA1cm that had been obtained by the substitution of the C-terminal six residues of POIA1 with those of the propeptide of subtilisin BPN'. When Ile32 or Ile64 was substituted with Ala, the tertiary structure of the resultant mutant was markedly destroyed, and the activities as a protease inhibitor and an intramolecular chaperone were significantly lowered. Among the position 44 mutants, the Phe44 --> Val mutant was a much less effective intramolecular chaperone with conversion to a digestible inhibitor, possibly owing to destruction of the tertiary structure. On the other hand, the Phe44 --> Leu or Ile mutant maintained its tertiary structure, and hence could function as a more effective intramolecular chaperone than the Phe44 --> Val mutant. Furthermore, since the Phe44 --> Leu mutant was a more susceptible inhibitor than POIA1cm, the halo formed around a colony of Bacillus cells transformed with a plasmid encoding this mutant was larger than others. These results clearly show the close relationship between the tertiary structure and functions of POIA1 as a protease inhibitor and an intramolecular chaperone, and that a combination of such inhibitory properties and intramolecular chaperone activity of POIA1 might affect the diameter of the halo formed around Bacillus colonies in vivo. 相似文献