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排序方式: 共有923条查询结果,搜索用时 18 毫秒
891.
In order to elucidate the origin of luminescent species in unstabilized commercial isotactic polypropylene (IPP), effects of hexane extraction and exposure of the extracted IPP film to the atmosphere on both fluorescence and phosphorescence emissions were examined. Fluorescence emission from the unextracted IPP film disappeared by the extraction, and only a very weak phosphorescence emission was found. During the exposure of the extracted IPP film to the atmosphere, both fluorescence and phosphorescence emissions appeared again. The intensity of the spectra increased with the exposure time and finally almost reached that from the unextracted IPP film. The results indicated that main fluorescent species in IPP are foreign impurities originating from an ambient atmosphere, and that contribution of a very minor amount of phosphorescence species such as carbonyl groups incorporated with the polymer was scarce. 相似文献
892.
893.
894.
Hideyuki Hara Yasuhisa Sano Keita Yagi Akihisa Kubota Kazuto Yamauchi 《Science and Technology of Advanced Materials》2007,8(3):162-165
A Si wafer and polysilicon deposited on a Si wafer were planarized using catalyst-referred etching (CARE). Two apparatuses were produced for local etching and for planarization. The local etching apparatus was used to planarize polysilicon and the planarization apparatus was used to planarize Si wafers. Platinum and hydrofluoric acid were used as the catalytic plate and the source of reactive species, respectively. The processed surfaces were observed by optical interferometry, atomic force microscopy (AFM) and scanning electron microscopy (SEM). The results indicate that the CARE-processed surface is flat and undamaged. 相似文献
895.
Sakoda H Fisher J Lu S Buchanan F 《Journal of materials science. Materials in medicine》2001,12(10-12):1043-1047
Oxidative degradation of UHMWPE has been found to be a cause of elevated wear rate of the polymer in total joint replacement leading to failure of these devices. In order to evaluate long term stability of polymers, various accelerated aging methods have been developed. In this study, wear rates of shelf aged UHMWPE and "accelerated aged" UHMWPE were compared using a multi-directional pin-on-plate wear test machine in order to evaluate the effect of the accelerated aging on wear. Wear factors of the aged materials were found to depend on their density, which is a measure of oxidation level. Finally, accelerated aging was calibrated against shelf aging in terms of wear rate. 相似文献
896.
A method of identifying closed-loop systems is developed by using the orthogonal decomposition (ORT) method. The idea is to project the input and output data onto the space of exogenous inputs by using the LQ decomposition to obtain their deterministic components. The ORT-based method is then applied to deterministic components like the direct approach in order to derive state-space models of the plant. We also show that the present method is a subspace version of the two-stage method for transfer function estimation from closed loop data. Some simulation results are included to show the applicability of the present method. 相似文献
897.
Hydrogen fermentation properties of undiluted cow dung 总被引:2,自引:0,他引:2
Yokoyama H Waki M Ogino A Ohmori H Tanaka Y 《Journal of Bioscience and Bioengineering》2007,104(1):82-85
Anaerobic treatment of undiluted cow dung (15% total solids), so-called dry fermentation, produced hydrogen (743 ml-H(2)/kg-cow dung) at an optimum temperature of 60 degrees C, with butyrate and acetate formation. The hydrogen production was inhibited by the addition of NH(4)(+) in a dose-dependent manner. A bacterium with similarity to Clostridium cellulosi was detected in the fermented dung by a 16S rDNA analysis. 相似文献
898.
Water-soluble metal working fluids are used for processing of aluminum alloy materials. This short article describes properties of new additives in water-soluble metal working fluids for aluminum alloy materials. Many half esters or diesters were prepared from the reactions of higher alcohols with acid anhydrides. Interestingly, diesters of PTMG (tetrahydrofuran oligomer, MW = 650 and 1000) and polybutylene oxide (MW = 650) with maleic anhydride and succinic anhydride showed both of an excellent anti-corrosion property for aluminum alloy and a good hard water tolerance. The industrial soluble type processing oils including these additives also showed anti-corrosion property and hard water tolerance. 相似文献
899.
Hyung-Mok Kim Junya Inoue Hideyuki Horii 《International Journal of Rock Mechanics and Mining Sciences》2004,41(6):959-974
Underground excavation can induce significant deformation of pre-existing joints in rock mass. Due to the sliding and opening of the joints, consequent changes in the flow characteristics of a jointed rock mass would be anticipated. In the present work, a number of numerical techniques are employed and combined in order to evaluate the excavation-induced changes in the flow properties of a jointed rock mass. These are represented by the Micromechanics-Based Continuum (MBC) model analysis (FE excavation analysis in a jointed rock mass), and FracMan/Mafic package (FE flow and transport analysis in the discrete network of joints). A separate computational module connecting these two codes is incorporated to modify initially imposed transmissivities into the excavation-induced ones. The effect of excavation on the flow properties is evaluated by including these excavation-induced transmissivity changes of individual joints in the FE flow analysis. The excavation-induced transmissivities are calculated by the numerical and analytical techniques developed for flow through a single rock joint. The calculation of the excavation-induced transmissivity involves the distributions of shear displacements and normal stresses around the excavation, and implicitly takes into account the effect of surface geometric roughness. A test simulation for a deep underground repository is performed to illustrate the typical results predicted in the proposed approach. 相似文献
900.
Solubilization of Myofibrils and Inhibition of Autolysis of Squid Mantle Muscle by Sodium Citrate 总被引:2,自引:0,他引:2
ABSTRACT: The effects of organic salts (sodium (Na)-citrate, Na-gluconate, and Na-succinate) on the solubilization of myofibrillar proteins and the inhibition of autolysis of squid mantle muscle were investigated. All of the organic compounds dissolved myofibrils as NaCl did. Na-citrate showed the strongest ability with half dissolving at 0.06 M. Half dissolving by Na-gluconate, Na-succinate, and NaCl were 0.27, 0.21, and 0.27 M, respectively. Dissolving myofibrils by Na-citrate was not accompanied by the acceleration of autolysis. Na-citrate above 0.25 M almost completely inhibited the autolysis. The inhibition of autolysis by Na-gluconate and Na-succinate was much less than that of Na-citrate. Consequently, it was concluded that Na-citrate was the organic salt to dissolve squid myofibrils without inducing autolysis. 相似文献