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排序方式: 共有535条查询结果,搜索用时 15 毫秒
171.
Kato S Kinemuchi T Tatewaki Y Okada S Masuhara A Kasai H Oikawa H 《Journal of nanoscience and nanotechnology》2011,11(4):3340-3344
Butadiyne nanocrystals in water are usually polymerized by UV or gamma-ray irradiation to give polydiacetylene (PDA) nanocrystals. In this study, we confirmed that solid-state polymerization of 1,6-di(N-carbazolyl)-2,4-hexadiyne (DCHD) and 5,7-dodecadiyn-1,12-diyl bis[N-(butoxycarbonyl-methyl)carbamate] (4BCMU) could be stimulated by water-soluble radical initiators. The radical initiators used were potassium peroxodisulfate, three kinds of azo-type compounds and a redox initiator. In all cases, the solid-state polymerization was confirmed by color change into blue indicating that PDA modified by the radical residues at the end was formed. However, nanocrystal cohesion occurred especially when the concentration of the initiators was high or the dispersion was kept for a long time. In order to improve the dispersion stability, two kinds of surfactants, i.e., sodium dodecyl sulfate (SDS) or dodecyltrimethylammonium chloride (DTMAC), were added to the DCHD nanocrystal aqueous dispersion. As a result, when anionic SDS was added, the solid-state polymerization of nanocrystals proceeded without coagulation and quantitative conversion was confirmed for all initiators. Cationic DTMAC has no effect on dispersion stabilization. PDA nanocrystal surfaces in water are negatively charged in nature and electric interaction of nanocrystals with the cations results in decrease of surface charge and aggregation of nanocrystals. 相似文献
172.
Ohtsuki T Kawasaki Y Kubota H Namiki T Iizuka T Shionoya N Yoshii N Ohara R Tanaka M Kobayashi H Sato K Kawamura Y 《Shokuhin eiseigaku zasshi. Journal of the Food Hygienic Society of Japan》2011,52(2):130-134
Carbon monoxide (CO) treatment of fish meat of tuna, yellowtail, tilapia etc. is not allowed in Japan, since it can maintain the red color for a longer period than the microbiological shelf life of fish meat. The official method for quantification of CO has a problem, in that a part of the CO is lost during the preparation of the fish sample. To solve this problem, we modified the official method in this study. We also applied this modified method to survey the contents of CO in tuna, yellowtail, young yellowtail, and tilapia. As a result, the modified method was found to be more suitable for CO quantification than the official method. An inter-laboratory study by 4 laboratories confirmed that the CO content of many samples of tilapia exceeded the regulation value, apparently due to the higher recovery of CO, compared to the official method. Therefore, it was suggested that the regulation value in the case of tilapia should be changed if this method is introduced as an official method. 相似文献
173.
Resveratrol increases CD68+ Kupffer cells colocalized with adipose differentiation‐related protein and ameliorates high‐fat‐diet‐induced fatty liver in mice
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174.
Masue-Slowey Y Kocar BD Jofré SA Mayer KU Fendorf S 《Environmental science & technology》2011,45(2):582-588
Soils are an aggregate-based structured media that have a multitude of pore domains resulting in varying degrees of advective and diffusive solute and gas transport. Consequently, a spectrum of biogeochemical processes may function at the aggregate scale that collectively, and coupled with solute transport, determine element cycling in soils and sediments. To explore how the physical structure impacts biogeochemical processes influencing the fate and transport of As, we examined temporal changes in speciation and distribution of As and Fe within constructed aggregates through experimental measurement and reactive transport simulations. Spherical aggregates were made with As(V)-bearing ferrihydrite-coated sand inoculated with Shewanella sp. ANA-3; aerated solute flow around the aggregate was then induced. Despite the aerated aggregate exterior, where As(V) and ferrihydrite persist as the dominant species, anoxia develops within the aggregate interior. As a result, As and Fe redox gradients emerge, and the proportion of As(III) and magnetite increases toward the aggregate interior. Arsenic(III) and Fe(II) produced in the interior migrate toward the aggregated exterior and result in coaccumulation of As and Fe(III) proximal to preferential flow paths as a consequence of oxygenic precipitation. The oxidized rind of aggregates thus serves as a barrier to As release into advecting pore-water, but also leads to be a buildup of this hazardous element at preferential flow boundaries that could be released upon shifting geochemical conditions. 相似文献
175.
Toshinobu Yoko Kanichi Kamiya Hiroyuki Yamada Katsuhisa Tanaka 《Journal of the American Ceramic Society》1988,71(2):70-C-
The glass-forming region for oxyhalide glasses in the system LiCl-Li2 O-TeO2 has been established. It extends to the LiCl-rich side, ranging from 15 to 60 mol% LiCl, whereas it is limited to only about 30 mol% Li2 O on the lithia-rich side. The reason for such an extended glass-forming region on addition of LiCl to TeO2 is discussed on the basis of the results of infrared spectroscopic measurements. 相似文献
176.
Masahide Takahashi Takashi Uchino Toshinobu Yoko 《Journal of the American Ceramic Society》2002,85(5):1089-1092
The photochemical transformation mechanism of defects in germanosilicate and silica glasses under ultraviolet (UV) laser irradiation has been investigated based on the changes in Raman spectra before and after irradiation. Two types of silica glasses, fused silica (type I) and dry synthetic silica (type IV), and germanosilicate optical fiber preforms were irradiated by intense UV photons from excimer lasers. Spectral changes in optical absorption and Raman spectra were examined to clarify a correlation between the microscopic defect formation and the macroscopic structural changes causing a photorefractive effect. Successive generation of E' centers through divalent centers is closely correlated with changes in Raman spectra, indicating that large structural changes in the glass network involved in this process would be the origin of photon-induced densification of the glasses. In addition, it has been proposed that the successive generation of E' centers is mediated by transient divalent centers converted from relaxed cation homobondings. 相似文献
177.
Deri R.J. Yasuoka N. Makiuchi M. Kuramata A. Wada O. Yamakoshi S. 《Electronics letters》1989,25(20):1355-1356
The authors demonstrate a low-loss 3 dB directional coupler for use in balanced coherent receivers for lightwave communications. The device exhibits 1.6-1.7 dB insertion loss and better than 52:48 splitting ratio at 1.54 mu m wavelength.<> 相似文献
178.
179.
Preparation of TiN fibres by ammonolysis of the sol-gel derived TiO2 fibres has been performed in the present study. TiO2 gel fibres were prepared from Ti(O-i-C3H7)4 by hydrolysis and polycondensation. As a result, TiN is found to form above 900°C. A thermodynamic interpretation of the nitridation reaction of TiO2 was considered. Moreover, from the kinetic treatment, it is found that the nitridation reaction of TiO2 is controlled by diffusion of either reactant (NH3) or one of the products (H2O) through the reaction layer. 相似文献
180.
Yamakoshi S. Abe M. Wada O. Komiya S. Sakurai T. 《Quantum Electronics, IEEE Journal of》1981,17(2):167-173
The reliability of high radiance InGaAsP/InP DH LED's operating in the1.2-1.3 mu m wavelength and the defect structures observed in this quaternary alloy have been presented. Threading dislocations and misfit dislocations do not act as strong nonradiative recombination centers, in contrast with the case in GaAs or GaAlAs optical devices. Dark-spot defects (DSD's) were sometimes generated in the emitting area during aging at elevated temperatures. These defects were analyzed microscopically using a transmission electron microscope and were identified as precipitates. To investigate the homogeneous degradation, accelerated aging at the ambient temperatures of 20, 60, 120, 170, 200, and 230°C has been carried out for over 15 000 h at the current density of 8 kA/cm2using LED's without dark structures. The degradation rates were statistically calculated by assuming the normal distribution. The mean values of degradation rates and the values of standard deviation were determined at the temperatures above 170°C. The activation energy of homogeneous degradation was determined to be 1.0 eV and the extrapolated half-life in excess of 109h was estimated at the ambient temperature of 60°C. 相似文献