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991.
T Kohno S Asai Y Iribe I Hosoi K Shibata K Ishikawa 《Canadian Metallurgical Quarterly》1998,81(1-2):199-205
We developed a method for in vivo real-time monitoring of the concentration of extracellular glutamate ([Glu]e) in the brain under anoxic conditions. A dialysis electrode (Sycopel Int., UK) was employed as a sensing device to measure the concentration of glutamate by enzyme amperometry, and an electron mediator, ferrocene, was introduced into the electrode together with glutamate oxidase. The ferrocene was covalently conjugated with a high molecular weight molecule, bovine serum albumin, to avoid outward diffusion through the dialysis membrane. With this set-up, the amperometric response was independent of the pO2 around the electrode in vitro up to 400 microM glutamate. Using this method, we investigated the dynamics of [Glu]e in the rat striatum during anoxia. [Glu]e increased rapidly at 102+/-5.4s (n = 6) after the start of nitrogen inhalation. The increase continued for about 30 s, and then [Glu]e decreased. The peak value of delta[Glu]e was 141+/-37 micro M. [Glu]e subsequently underwent another gradual increase, reaching 213+/-69 microM at 15 min after the start of nitrogen inhalation. This distinct biphasic profile was reproducible. We conclude that this method is very useful for monitoring [Glu]e in the brain under low pO2 conditions. 相似文献
992.
Tetsuya Yagi Haruo Kobayashi Takashi Matsumoto Koji Tanaka 《Artificial Life and Robotics》1998,2(1):12-18
Light adaptive algorithms/architectures are proposed for regularization vision chips. The adaptation mechanisms allow the
regularization parameters to change in an adaptive manner in accordance with the light intensity of given images. This is
achieved by adaptively changing the conductance values associated with massively parallel resistive networks. The algorithms/architectures
are inspired by the adaptation mechanisms of the retinal horizonal cells of the lower vertebrates.
This work was presented, in part, at the International Symposium on Artificial Life and Robotics, Oita, Japan, February 18–20,
1996 相似文献
993.
994.
Mitsutaka Hino Tetsuya Nagasaka Kenichi Higuchi Shiro Ban-Ya 《Metallurgical and Materials Transactions B》1998,29(2):351-360
The thermodynamics for reduction of iron-chromium ore by carbon is discussed. The thermodynamic properties of iron-chromium
ore were evaluated from our previous work on the activities of constituents in the FeO·Cr2O3-MgO·Cr2O3-MgO·Al2O3 iron-chromite spinel-structure solid solution saturated with (Cr, Al)2O3, and those of the Fe-Cr-C alloy were estimated by a sublattice model. The stability diagrams were drawn for carbon reduction
of pure FeO · Cr2O3, (Fe0.5Mg0.5)O·(Cr0.8Al0.2)2O3 iron-chromite solid solution, and South African iron-chromium ore. The evaluated stability diagrams agreed well with the
literature data. It was concluded that the lowest temperature for reduction of FeO · Cr2O3 in the iron-chromium ore was 1390 K and a temperature higher than 1470 K would be necessary to reduce Cr2O3 in MgO·(Cr,Al)2O3 in the prereduction process of iron-chromium ore. The composition of liquid Fe-Cr-C alloy in equilibrium with iron-chromium
ore was also estimated under 1 atm of CO at steelmaking temperature. The predicted metal composition showed reasonable agreement
with the literature values. 相似文献
995.
S Nagamura A Asai N Amishiro E Kobayashi K Gomi H Saito 《Canadian Metallurgical Quarterly》1997,40(6):972-979
A series of N-cinnamates of the A-ring pyrrole compound of duocarmycin were synthesized and evaluated for in vitro anticellular activity against HeLa S3 cells and in vivo antitumor activity against murine sarcoma 180 in mice. The 4'-methoxy- and 4'-BocNH-cinnamates exhibited strong in vitro anticellular activity among the synthesized compounds. The ortho substitution of the 4'-methoxycinnamate did not affect the anticellular activity and contributed to an enhancement of water solubility. Most of the 8-O-(N,N-dialkylcarbamoyl) derivatives of the 4'-methoxycinnamate displayed remarkably superior in vivo antitumor activity to duocarmycin A or B2. Moreover, it is noteworthy that these 8-O-(N,N-dialkylcarbamoyl) derivatives exhibited significant antitumor activity at wider range of doses as compared with the A-ring pyrrole derivatives having the trimethoxyindole skeleton in segment B. 相似文献
996.
Satoru Asai Hidemi Nakamura Yasuhiro Konishi 《Korean Journal of Chemical Engineering》1997,14(5):307-311
In our recent studies, absorption of H2S into the aqueous Fe2(SO4)3 and FeCl3 solutions with various values of ionic strength and pH was investigated in an agitated vessel with a flat interface. The
experimental results for both systems revealed that the species which reacts with H2S is FeOH2+. The absorption rates were explained by the theory of gas absorption with an irreversible (l,l)-th order reaction between
H2S and FeOH2+. The reaction rate constants were independent of the ionic strength of the solution and correlated as a function of temperature.
In this paper, kinetics and mechanism of these absorption reactions are reviewed and the identity for both systems is emphasized. 相似文献
997.
The orphan nuclear receptor steroidogenic factor 1 (SF-1) was initially isolated as a key regulator of the cytochrome P450 steroid hydroxylases in adrenocortical and gonadal cells. Subsequent analyses of SF-1 knockout mice have expanded considerably our understanding of the roles that SF-1 plays in endocrine development. These SF-1 knockout mice lacked adrenal glands and gonads, with consequent male-to-female sex reversal of their internal and external genitalia. Thus, SF-1 is essential for the embryonic survival of the primary steroidogenic organs. They further exhibited impaired gonadotrope function and agenesis of the ventromedial hypothalamic nucleus, establishing that SF-1 contributes to reproductive function at all three levels of the hypothalamic-pituitary-gonadal axis. This report reviews experiments that have defined these critical roles of SF-1 in endocrine development, and highlights areas of ongoing investigation. 相似文献
998.
We prepared proton exchange membranes by the γ-ray-induced post grafting of styrene into crosslinked polytetrafluoroethylene (PTFE) films and subsequent sulfonation. The degree of grafting was controlled in the range of 7-75% by the crosslinking density of the PTFE matrix as well as the grafting conditions. Under our preparation conditions, the films at the grafting yield of ≥30% were found to produce ion exchange membranes with a homogeneous distribution of sulfonic acid groups. The resulting membranes showed a large ion exchange capacity up to 2.9 meq g−1, which exceeded the performance of commercially available perfluorosulfonic acid films such as Nafion; nevertheless, they appeared to be dimensionally stable in water. These should undoubtedly result from the use of the crosslinked PTFE films as graft substrates and make our ion exchange membranes promising for applications to polymer electrolyte fuel cells. 相似文献
999.
It is shown that a feedback system is robustly stable with respect to small time delays if and only if it is stable for zero time delay and a structured singular value is less than one. 相似文献
1000.
Low dielectric constant materials and methods for interlayer dielectric films in ultralarge-scale integrated circuit multilevel interconnections 总被引:3,自引:0,他引:3
Tetsuya Homma 《Materials Science and Engineering: R: Reports》1998,23(6):243-285
This paper reviews low dielectric constant materials for interlayer dielectric films in ultralarge-scale integrated circuit (ULSI) multilevel interconnections. The trends of ULSIs in the last decade were briefly described first. Then, the requirements for interlayer dielectric film properties and their formation techniques were explained. They are: (1) a low dielectric constant, (2) a surface planarity, (3) a gap-filling capability, and (4) a low residual stress. In contrast with the requirements, the interlayer dielectric films and related technologies developed in the last decade were reviewed. In the requirements, the low dielectric constant materials are strongly required because the device performance has been limited by signal propagation time and cross-talk in the multilevel interconnections. Furthermore, the low dielectric constant is also required for reduction of power consumption in ULSI operation. Finally, the low dielectric constant materials were summarized, and future trends of the low dielectric constant interlayer dielectric film technologies are discussed. 相似文献