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261.
In this study, microbial precipitation of carbonate was observed using high microbial urease activity, and it was found that the ratio of Mg/Ca affected the types of crystals produced. Without Mg2+, calcite was produced using only CaCl2, while the presence of Mg produced Mg-calcite, magnesite and/or possibly dolomite of round, spherical or fibrous shapes, depending on reaction time, pH and Mg/Ca ratio. The carbonate produced contributed to the development of cementation for sands. The presence of Mg showed a relatively strong cementation of the carbonate. 相似文献
262.
The difference between the threshold voltages V/sub t/ of pMOS and nMOS transistors is a critical issue in the low-voltage operation of CMOS circuits. The pMOS/nMOS V/sub t/ balancing profit is analyzed in terms of subthreshold leakage current and the performance of CMOS LSIs and the minimum supply voltage of logic circuits. Matching the pMOS/nMOS V/sub t/ improves LSI performance and reduces the lowest supply voltage by 0.15 V. We propose a new concept of body bias management that uses forward biasing, fluctuation compensating, and V/sub t/ matching technologies to resolve the issue. 相似文献
263.
Isao Furukawa Mitsuru Nomura Sadayasu Ono 《Signal Processing: Image Communication》1993,5(5-6):527-538
A hierarchical image coding algorithm based on sub-band coding and adaptive block-size multistage vector quantization (VQ) is proposed, and its coding performance is examined for super high definition (SHD) image. First, the concept on SHD image is briefly described. Next, the signal power spectrum is evaluated, and the sub-band analysis pattern is determined from its characteristics. Several quadrature mirror filters are examined from the viewpoints of reconstruction accuracy, coding gain, and low-pass signal quality. Then an optimum filter is selected for the sub-band analysis. The two-stage VQ using the adaptive bit allocation is also introduced to control quantization accuracy and to achieve high-quality image reproduction. Coding performance and hierarchical image reconstruction are demonstrated using SNR and some photographs. 相似文献
264.
Saito M. Yoshitomi T. Hara H. Ono M. Akasaka Y. Nii H. Matsuda S. Momose H.S. Katsumata Y. Ushiku Y. Iwai H. 《Electron Devices, IEEE Transactions on》1993,40(12):2264-2272
A p-MOSFET structure with solid-phase diffused drain (SPDD) is proposed for future 0.1-μm and sub-0.1-μm devices. Highly doped ultrashallow p+ source and drain junctions have been obtained by solid-phase diffusion from a highly doped borosilicate glass (BSG) sidewall. The resulting shallow, high-concentration drain profile significantly improves short channel effects without increasing parasitic resistance. At the same time, an in situ highly-boron-doped LPCVD polysilicon gate is introduced to prevent the transconductance degradation which arises in ultrasmall p-MOSFETs with lower process temperature as a result of depletion formation in the p+-polysilicon gate. Excellent electrical characteristics and good hot-carrier reliability are achieved 相似文献
265.
Chihiro J. Uchibori Y. Ohtani T. Oku Naoki Ono Masanori Murakami 《Journal of Electronic Materials》1997,26(4):410-414
Significant reduction of the contact resistance of In0.7Ga0.3As/Ni/W contacts (which were previously developed by sputtering in our laboratory) was achieved by depositing a W2N barrier layer between the Ni layer and W layer. The In0.7Ga0.3 As/Ni/W2N/W contact prepared by the radio-frequency sputtering technique showed the lowest contact resistance of 0.2 Ωmm after annealing
at 550°C for 10 s. This contact also provided a smooth surface, good reproducibility, and excellent thermal stability at 400°C.
The polycrystalline W2N layer was found to suppress the In diffusion to the contact surface, leading to improvement of the surface morphology and
an increase in the total area of the InxGa−As between metal and the GaAs substrate. These improvements are believed to reduce the contact resistance. 相似文献
266.
Yamada M. Mori A. Kobayashi K. Ono H. Kanamori T. Oikawa K. Nishida Y. Ohishi Y. 《Photonics Technology Letters, IEEE》1998,10(9):1244-1246
We describe a tellurite-based Er3+-doped fiber amplifier (EDFA) with a flat amplification bandwidth of 76 nm and a noise figure of less than 7 dB. Furthermore, a parallel-type amplifier composed of this EDFA and a 1.45-μm-band Tm3+-doped fluoride fiber amplifier achieved a flat amplification bandwidth of 113 nm 相似文献
267.
1.5 nm direct-tunneling gate oxide Si MOSFET's 总被引:6,自引:0,他引:6
Sasaki H. Ono M. Yoshitomi T. Ohguro T. Nakamura S. Saito M. Iwai H. 《Electron Devices, IEEE Transactions on》1996,43(8):1233-1242
In this paper, normal operation of a MOSFET with an ultra-thin direct-tunneling gate oxide is reported for the first time. These high current drive n-MOSFET's were fabricated with a 1.5 nm direct-tunneling gate oxide. They operate well at gate lengths of around 0.1 μm, because the gate leakage current falls in proportional to the gate length, while the drain current increases in inverse proportion. A current drive of more than 1.0 mA/μm and a transconductance of more than 1,000 mS/mm were obtained at a gate length of 0.09 μm at room temperature. These are the highest values ever obtained with Si MOSFET's at room temperature. Further, hot-carrier reliability is shown to improve as the thickness of the gate oxide is reduced, even in the 1.5 nm case. This work clarifies that excellent performance-a transconductance of over 1,000 mS/mm at room temperature-can be obtained with Si MOSFET's if a high-capacitance gate insulator is used 相似文献
268.
Propagation measurements were carried out at 12 GHz on the down-link of the Japan's Medium-scale Broadcasting Satellite for Experimental Purpose (BSE), launched in 1978. Analyses of the measurements have revealed the statistics of rain attenuation and duration of fade at 12 GHz in various parts and climates of Japan, as well as other environmental effects such as degradation of reception quality due to snowfall on receiving antennae, reduction in carrier-to-noise ratio by solar noise interference and diffraction attenuation by obstacles. This paper describes the results which are useful for planning and operation of satellite broadcasting systems. 相似文献
269.
The ratios and quantities of the pheromone components, (E,Z)-4,7-tridecadien-1-yl acetate (diene) and (E,Z,Z)-4,7.10-tridecatrien-1-yl acetate (triene), in the glands of individual female potato tuberworm moths (Phthorimaea operculella) originating from the United States (California) and Japan (Nagoya) were analyzed by gas chromatography. Quantities of glandextracted pheromone components of Nagoya females fluctuated in a periodic fashion during the photoperiod. Maximal titers coincided with the onset of scotophase (and calling), then gradually declined to minimal levels soon after lights-on. The average daily pheromone quantities decreased significantly as females aged. Both populations exhibited considerable variation in the ratio of the two components. The proportions of triene in the blend ranged from 27% to 88% (triene –X = 56 ± 13% SD; CV = 23%) for California females and from 16% to 71% (42 ± 13%; CV = 31%) for Nagoya females. Nagoya females also stored significantly higher amounts of pheromone in their glands (8.6 ± 3.9 ng) than did California females (2.7 ± 1.4). The differences between the populations, while substantial, would probably not be sufficient to impart a barrier to panmixis, given the wide range of component ratios favored by the males. 相似文献
270.
Atherogenic effect of oxidized products of cholesterol 总被引:4,自引:0,他引:4
Cholesterol under certain in vitro and possibly in vivo conditions may be oxidized to oxysterols, which are suspected of being initiators of atherosclerotic plaques. Oxysterols inhibit HMG-CoA reductase activity resulting in a decreased cholesterol concentration in the cell membrane, which leads to endothelial membrane injury and probable premature cell death. Exogenous oxidation of cholesterol in human tissues under certain unusual conditions is highly probable. Dietary oxysterols are absorbed in the gastrointestinal tract and are selectively transported by the athrogenic lipoproteins LDL and VLDL. The oxysterols cholestanetriol and 25-OH cholesterol have been shown to be atherogenic. Oxysterols are commonly found in dried egg products, powdered milk, cheeses and in a variety of high temperature dried animal products. 相似文献