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排序方式: 共有117条查询结果,搜索用时 15 毫秒
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Yoshihiro Hirata Kazuyoshi Sakeda Yumi Matsushita Kinji Shimada Yoshimi Ishihara 《Journal of the American Ceramic Society》1989,72(6):995-1002
Submicrometer SiO2 -Al2 O3 powders with compositions of 46.5 to 76.6 wt% Al2 O3 were prepared by hydrolysis of mixed alkoxides. Phase change, mullite composition, and particle size of powders with heating were analyzed by DTA, XRD, IR, BET, and TEM. As-produced amorphous powders partially transformed to mullite and Al-Si spinel at around 980°C. The compositions of mullite produced at 1400° and 1550°C were richer in Al2 O3 than the compositions of stable mullite solid solutions predicted from the phase diagram of the SiO2 -Al2 O3 system. Particle size decreased with increasing Al2 O3 content. The sintered densities depended upon the amount of SiO2 -rich glassy phase formed during sintering and the green density expressed as a function of particle size. 相似文献
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Tomoya Hasegawa Mikako Ito Satoru Hasegawa Masaki Teranishi Koki Takeda Shuto Negishi Hiroshi Nishiwaki Jun-ichi Takeda Tyler W. LeBaron Kinji Ohno 《International journal of molecular sciences》2022,23(5)
Molecular hydrogen ameliorates pathological states in a variety of human diseases, animal models, and cell models, but the effects of hydrogen on cancer have been rarely reported. In addition, the molecular mechanisms underlying the effects of hydrogen remain mostly unelucidated. We found that hydrogen enhances proliferation of four out of seven human cancer cell lines (the responders). The proliferation-promoting effects were not correlated with basal levels of cellular reactive oxygen species. Expression profiling of the seven cells showed that the responders have higher gene expression of mitochondrial electron transport chain (ETC) molecules than the non-responders. In addition, the responders have higher mitochondrial mass, higher mitochondrial superoxide, higher mitochondrial membrane potential, and higher mitochondrial spare respiratory capacity than the non-responders. In the responders, hydrogen provoked mitochondrial unfolded protein response (mtUPR). Suppression of cell proliferation by rotenone, an inhibitor of mitochondrial ETC complex I, was rescued by hydrogen in the responders. Hydrogen triggers mtUPR and induces cell proliferation in cancer cells that have high basal and spare mitochondrial ETC activities. 相似文献
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Compact structure and flexibility is normally considered as a pair of incompatible characteristics for legged microrobots. Most robots choose complex structure of multi-joint legs to attain the flexibility, while some microrobots have poor flexibility for miniaturization. To attain a microrobot with both compact structure and flexible locomotion, we designed a novel type of biomimetic locomotion employing ionic conducting polymer film (ICPF) actuators as one-DOF legs. We developed several prototype microrobots using this locomotion. In this paper, a microrobot using this biomimetic locomotion, named Walker-3, utilizing six ICPF actuators with two-DOF motion is developed. It is 30 mm in length, 55 mm in width and 8 mm in height (in static state). Experimental results indicate that Walker-3 can attain 6 mm/s of walking speed and 7.1 deg/s of rotating speed and climb on a 30° ascent at a speed of 0.5 mm/s with control signal of 10 V, 0.5 Hz. It is also suitable for uncertain terrain, such as climbing on a stairs less than 2 mm high and striding over a pit less than 5 mm wide. It has better flexibility, balance and load ability than its predecessors. We compared it with some legged microrobots and the result shows a microrobot with this biomimetic locomotion can have both compact structure and multi DOF locomotion. 相似文献
7.
SE Fong JD Greenwood JC Williamson D Derse LA Pallansch T Copeland L Rasmussen A Mentzer K Nagashima G Tobin MA Gonda 《Canadian Metallurgical Quarterly》1997,233(2):339-357
cDNAs encoding the bovine immunodeficiency virus (BIV) transactivator gene (tat) were cloned from virally infected cells and characterized. BIV expresses two distinct tat mRNAs composed of three exons that are derived by alternative splicing. The BIV tat mRNA splice variants encode Tat proteins of 103 (Tat103) and 108 (Tat108) amino acids. The Tat103 coding region is specified only by exon 2, while that of Tat108 is specified by a truncated exon 2 and the first 30 nt of exon 3. Thus, the first 98 amino acids of each Tat are identical, and have amino terminal, cysteine-rich, conserved core, basic, and carboxyl-terminal domains similar to Tats encoded by primate lentiviruses. BIV-infected bovine cells express a 14-kDa phosphorylated Tat protein identical in size to recombinant Tat expressed in bacteria. BIV Tat was shown to localize exclusively in the nucleoli of virally infected and Tat-expressing cells. Reporter gene assays indicated that Tat103 and Tat108 can strongly transactivate the BIV long terminal repeat (LTR) in virally permissive canine Cf2Th and nonpermissive HeLa and mouse NIH 3T3 cells, but not in permissive lapine EREp cells. However, an intact BIV tat gene is required for viral replication in both Cf2Th and EREp cells. Strong LTR activation by BIV Tat requires a TAR (transactivation responsive) element delimited by viral nt +1 to +31 and the Tat basic domain. BIV Tat strongly cross-transactivates the HIV-1 LTR in a TAR-dependent manner in Cf2Th, but not in EREp, HeLa, or NIH 3T3 cells. In contrast, strong, TAR-dependent cross-transactivation of the BIV LTR by HIV-1 Tat could not be demonstrated in any of these cell types. In Cf2Th cells Tat108 effects a moderately stronger transactivation of the BIV LTR than Tat103, indicative of a functional difference in BIV Tat proteins encoded by the mRNA splice variants. The present studies demonstrate that BIV Tat parallels the primate lentiviral Tats in structure and biochemistry but is not interchangeable with the latter. 相似文献
8.
Kinji Magara 《Journal of Petroleum Geology》1981,4(2):177-186
In order for the hydrodynamics of meteoric water to be an important trapping mechanism for hydrocarbon accumulations, it must have existed for a long geologic period extending from the time of secondary hydrocarbon migration and its accumulation to the present time. However, in most interior sedimentary basins, the present hydrodynamic patterns are considered to have been developed only a short while ago (geologically speaking), after the significant uplift and the associated erosional events which caused the present topographical relief. Most petroleum accumulations were probably formed a long time before the development of the present hydrodynamic flow patterns, and hence must be explained by different mechanisms that have been effective for a much longer geologic period.
This paper also discusses other possible problems in applying the hydrodynamics concept to understanding the formation of petroleum accumulations, such as the lack of proper water passways and outlets in several basins, the difficulty of moving water through hydrocarbon-saturated sections of a reservoir, and the difficulty of keeping significant salinity gradients in a reservoir where active water flow has taken place. 相似文献
This paper also discusses other possible problems in applying the hydrodynamics concept to understanding the formation of petroleum accumulations, such as the lack of proper water passways and outlets in several basins, the difficulty of moving water through hydrocarbon-saturated sections of a reservoir, and the difficulty of keeping significant salinity gradients in a reservoir where active water flow has taken place. 相似文献
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Time-resolved spectral output of pulsed GaAs lasers 总被引:1,自引:0,他引:1
When pulse operated, all injection lasers show a laser line shift which is linear with time during the pulse length. This is evident for time-resolved spectra obtained by a scanning technique. The data present time-resolved spectra for pulse-operated gallium arsenide laser diodes. At high peak current values, joule heating results and the time-resolved laser spectra are seen to shift to longer wavelengths. A line-shift coefficient is defined for which the units are angstroms per (ampere)2per microsecond. For high peak current and long pulse length, the laser lines may shift one hundred angstroms or more. 相似文献