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排序方式: 共有285条查询结果,搜索用时 15 毫秒
1.
Suemasu T. Kohno Y. Saitoh W. Watanabe M. Asada M. 《Electron Devices, IEEE Transactions on》1995,42(12):2203-2210
We report on the theoretical and measured characteristics of triple-barrier metal (CoSi2)-insulator(CaF2) (M-I) resonant tunneling transistors (RTT) grown on an n-Si(111) substrate, and the influence of their parasitic elements on the measured characteristics. First, we analyze theoretical characteristics of an M-I RTT, and then show fabrication process and current-voltage (I-V) characteristics obtained at 77 K, in which several degradations are observed: large resonance voltage, low peak-to-valley (P-V) ratios at negative differential resistance (NDR), and reverse base current. Analysis, taking several parasitic elements (e.g., base resistance, substrate resistance and leakage currents connected to the intrinsic transistor) into account, explains observed characteristics well. Finally, we show the first transistor action with large P-V ratios at 300 K, which is achieved by reducing collector-emitter leakage currents 相似文献
2.
Masayuki Asada Yoshinari Miura Akiyoshi Osaka Katsutoshi Oukami Seishiro Nakamura 《Journal of Materials Science》1988,23(9):3202-3205
Calcium hydroxyapatite (Ca-HAP) ceramics containing tricalcium phosphate (TCP) were soaked in three solutions: phosphate buffer, tris buffer, and simulated body fluid (SBF). Petal-like crystals of Ca-HAP were deposited on the Ca-HAP ceramics when (i) Ca-HAP ceramics contained -TCP, (ii) the soaking solution contained phosphate ion and (iii) the pH of soaking solution was higher than 7.3. These conditions facilitate the presence of HPO
4
2–
and Ca2+ ions, the latter from dissolution of -TCP. A well-defined X-ray diffraction pattern for the deposited Ca-HAP crystals indicates preferred growth of {002} planes. Slower crystal growth of Ca-HAP was found for SBF (pH=7.5) than in the phosphate buffer, due possibly to the lower phosphate ion content in SBF. 相似文献
3.
A new optical element capable of converting linear polarization into circular-tangential polarization (i.e., the electric vector is along the tangential direction to a circle) is proposed and demonstrated. The conversion characteristics of the fabricated element are evaluated, and the magnitude of aberration produced by the element is shown to be insignificant. 相似文献
4.
An interference method utilizing conic-wave-front light for the fabrication of a concentric-circular and chirped grating is proposed. The design method and fabrication of an interference lens that generates conic-wave-front light are also shown. A focusing element is constructed from a concentric-circular grating coupler with a 0.4-mm diameter and a concentric-circular focusing grating coupler with an annular aperture of 2-mm focal length and 2.0-4.0-mm diameter. Light-convergence experiments using the focusing element were able to obtain a focusing spot of 0.5 μm × 0.7 μm at half-intensity widths for a wavelength of 820 nm in combination with liquid-crystal polarization elements. 相似文献
5.
Min-Cheol Kim Raymond H. W. Lam Todd Thorsen H. Harry Asada 《Microfluidics and nanofluidics》2013,15(3):285-296
For successful cell culture in microfluidic devices, precise control of the microenvironment, including gas transfer between the cells and the surrounding medium, is exceptionally important. The work is motivated by a polydimethylsiloxane (PDMS) microfluidic oxygenator chip for mammalian cell culture suggesting that the speed of the oxygen transfer may vary depending on the thickness of a PDMS membrane or the height of a fluid channel. In this paper, a model is presented to describe the oxygen transfer dynamics in the PDMS microfluidic oxygenator chip for mammalian cell culture. Theoretical studies were carried out to evaluate the oxygen profile within the multilayer device, consisting of a gas reservoir, a PDMS membrane, a fluid channel containing growth media, and a cell culture layer. The corresponding semi-analytical solution was derived to evaluate dissolved oxygen concentration within the heterogeneous materials, and was found to be in good agreement with the numerical solution. In addition, a separate analytical solution was obtained to investigate the oxygen pressure drop (OPD) along the cell layer due to oxygen uptake of cells, with experimental validation of the OPD model carried out using human umbilical vein endothelial cells cultured in a PDMS microfluidic oxygenator. Within the theoretical framework, the effects of several microfluidic oxygenator design parameters were studied, including cell type and critical device dimensions. 相似文献
6.
We investigated a simple field effect passivation of the silicon surfaces using the high-pressure H2O vapor heating. Heat treatment with 2.1×106 Pa H2O vapor at 260°C for 3 h reduced the surface recombination velocity from 405 cm/s (before the heat treatment) to 38 cm/s for the thermally evaporated SiOx film/Si. Additional deposition of 140 nm-SiOx films (x<2) with a high density of fixed positive charges on the SiO2/Si samples further decreased the surface recombination velocity to 22 cm/s. We also demonstrated the field effect passivation for n-type silicon wafer coated with thermally grown SiO2. Additional deposition of 210 nm SiOx films on both the front and rear surfaces increased the effective lifetime from 1.4 to 4.6 ms. Combination of thermal evaporation of SiOx film and the heat treatment with high-pressure H2O vapor is effective for low-temperature passivation of the silicon surface. 相似文献
7.
Uzawa M Sakurai K Okuyama S Asada S Sakanoshita M Tsukada K Kawahara S 《Shokuhin eiseigaku zasshi. Journal of the Food Hygienic Society of Japan》2004,45(2):67-72
We have developed an analytical method for terpene resins in chewing gum. The fraction including terpene resins was prepared by means of hexane extraction and two silica gel column chromatography treatments (hexane and ethyl acetate) from chewing gum. The terpene resin fraction was analyzed with LC/MS and IR. The terpene resins are mixtures of polymeric pinene and/or limonene, which have a monomer molecular weight of 136. The MS spectrum of the terpene resin peak on the LC/MS total ion chromatogram showed protonated molecular ion (M + H)+ peaks at intervals of m/z 136, characteristic of a complex mixture of polyterpenes. IR spectroscopy is a suitable technique to identify the terpene resin type, ie., pinene or limonene. When the method was applied to imported chewing gum sold in Japan, terpene resins were clearly detected. 相似文献
8.
M Fujita K Nomura K Hong Y Ito A Asada S Nishimuro 《Canadian Metallurgical Quarterly》1993,197(3):1340-1347
A strong fibrinolytic enzyme (nattokinase) was purified from the vegetable cheese natto. Nattokinase was extracted from natto with saline and isolated by sequential use of hydrophobic chromatography on Butyl-Toyopearl, ion-exchange chromatography on CM-Toyopearl, and gel-filtration on Sephadex G-50. The isolated protein gave a single sharp band on SDS-PAGE either before or after reduction. The sequence, as determined by automated Edman degradation of the uncleaved molecule and its enzymatically derived peptide, consisted of a total 275 amino acid residues (M.W = 27,728) and exhibited a high homology with the subtilisins. The purified nattokinase digested not only fibrin but also several synthetic substrates. Among the synthetic substrates, the most sensitive substrate was Suc-Ala-Ala-Pro-Phe-pNA for subtilisin. PMSF inhibited both the fibrinolytic activity and the amidolytic activity. The results indicate that nattokinase is a subtilisin-like serine protease. 相似文献
9.
Masahiro Ishida Toru Nakura Takashi Kusaka Satoshi Komatsu Kunihiro Asada 《Journal of Electronic Testing》2016,32(3):257-271
This paper proposes a power integrity control technique for dynamically controlling power supply voltage fluctuations for a device under test (DUT), and demonstrates its effectiveness for eliminating the overkills/underkills due to the difference of power supply impedance between an automatic test equipment (ATE) and a practical operating environment of the DUT. The proposed method injects compensation currents into the power supply nodes on the ATE system in a feed-forward manner such that the ATE power supply waveform matches with the one on the customer’s operating environment of the DUT. A method for calculating the compensation current is also described. Experimental results show that the proposed method can emulate the power supply voltage waveform under a customer’s operating condition and eliminate 95 % of overkills/underkills in the maximum operating frequency testing with 105 real silicon devices. Limitations and applications of the proposed method are also discussed. 相似文献
10.
Kenji Takizawa Tayfun E. Tezduyar Austin Buscher Shohei Asada 《Computational Mechanics》2014,54(4):955-971
To address the computational challenges associated with contact between moving interfaces, such as those in cardiovascular fluid–structure interaction (FSI), parachute FSI, and flapping-wing aerodynamics, we introduce a space–time (ST) interface-tracking method that can deal with topology change (TC). In cardiovascular FSI, our primary target is heart valves. The method is a new version of the deforming-spatial-domain/stabilized space–time (DSD/SST) method, and we call it ST-TC. It includes a master–slave system that maintains the connectivity of the “parent” mesh when there is contact between the moving interfaces. It is an efficient, practical alternative to using unstructured ST meshes, but without giving up on the accurate representation of the interface or consistent representation of the interface motion. We explain the method with conceptual examples and present 2D test computations with models representative of the classes of problems we are targeting. 相似文献