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  • 1
    Electronic Resource
    Electronic Resource
    Characterization of growth interruption interface by mobility profiling (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 2211-2215 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A mobility profiling technique using a field-effect transistor has been successfully applied to characterize the growth interruption interfaces of organometallic vapor-phase epitaxial Si-doped n-GaAs layers. The interface was formed by interrupting the supply of TMGa and SiH4 for certain lengths of time under a pressure of flowing AsH3. The 30-s interruption interface showed a decrease in the carrier concentration and an increase in the mobility, as obtained from the gate capacitance-voltage and transconductance-voltage characteristics. A quantitative analysis led us to a conclusion that the interface in question is not compensated by acceptor impurities or defects, in contrast with an easy conclusion usually deduced only from the carrier concentration profile, but has an effective reduction of Si doping level. A secondary-ion mass spectroscopic (SIMS) depth analysis of Si and C atoms supported the above-mentioned conclusion. The 60-s interruption, however, showed an extremely low drain current, which was caused by overcompensation of Si by C pileup at the interface, as confirmed from the SIMS depth profile. Thus, it was found that electrical compensation of the interface rapidly proceeds during 30–60-s interruption. The mobility profiling, therefore, provides a sensitive and powerful tool for growth interruption analysis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.349465
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  • 2
    Electronic Resource
    Electronic Resource
    MKC-231, a choline uptake enhancer, ameliorates working memory deficits and decreased hippocampal acetylcholine induced by ethylcholine aziridinium ion in mice (1994)
    Springer
    Journal of neural transmission 98 (1994), S. 1-13 
    Details
    ISSN: 1435-1463
    Keywords: MKC-231 ; ethylcholine aziridinium ion (AF64A) ; Dup 996 ; THA ; hippocampal acetylcholine ; delayed non-matching to sample task ; working memory deficit
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effects of acute and chronic administration of MKC-231, a new choline uptake enhancer, and two other nootropic agents, linopiridine (Dup 996) and tetrahydroaminoacridine (THA) on working memory deficits and decreased hippocampal acetylcholine (ACh) content were studied in a delayed non-matching to sample task, using a T-maze, in ethylcholine aziridinium ion (AF64A)-treated mice. Treatment with AF64A (3.5 nmol, i.c.v.) produced memory deficits and decreased hippocampal ACh content. In acute behavioral experiments, MKC-231 and THA had no significant effect on AF64A-induced memory deficits at any doses tested (0.3, 1.0 and 3.0mg/kg), whereas Dup 996, at a dose of 1.0mg/kg, significantly improved memory deficits. In chronic experiments, MKC-231 improved memory deficit at all doses tested (0.3, 1.0, or 3.0mg/kg p.o., once daily for 11 days) and Dup 996 did so only at a dose of 3.0 mg/kg, whereas THA did not improve memory deficit at any doses tested. In acute neurochemical experiments, MKC-231 and THA did not reverse the AF64A-induced hippocampal ACh depletion. Dup 996, however, further decreased hippocampal ACh content compared to that in the AF64A-treated group. In chronic experiments, MKC-231 significantly reversed hippocampal ACh depletion at doses of 0.3 and 1.0mg/kg, whereas neither Dup 996 nor THA reversed hippocampal ACh depletion at any doses tested. These results indicate that MKC-231 improved the AF64A-induced working memory deficit and hippocampal ACh depletion, probably by recovering reduced high-affinity choline uptake and ACh release.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01277590
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  • 3
    Electronic Resource
    Electronic Resource
    A rapid assay for neurotransmitter amino acids, aspartate, glutamate, glycine, taurine and γ-aminobutyric acid in the brain by high-performance liquid chromatography with electrochemical detection (1992)
    Springer
    Journal of neural transmission 87 (1992), S. 145-153 
    Details
    ISSN: 1435-1463
    Keywords: Amino acid neurotransmitters ; HPLC-ECD ; mouse brain ; electroconvulsive shock
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary For simultaneous assay of the five neurotransmitter amino acids, Asp, Glu, Gly, Tau, and GABA in brain tissues, a very rapid and simple chromatographic method using high-performance liquid chromatography with electrochemical detection in combination with o-phthalaldehyde derivatization is described. Because the present method permits the determination of these five amino acids within less than five minutes in one chromatographic run, up to 100 samples a working day can be analyzed using an autosampler. Withinrun coefficients of variation for these five amino acids were less than 2% (n=20). The quantitative detection limit was 2.5 pmol for the 5 amino acids. The present method has been applied to the measurement of the five amino acid neurotransmitter levels in several discrete brain regions of mice treated with and without electroconvulsive shock.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01245016
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  • 4
    Electronic Resource
    Electronic Resource
    Effects of nefiracetam on deficits in active avoidance response and hippocampal cholinergic and monoaminergic dysfunctions induced by AF64A in mice (1994)
    Springer
    Journal of neural transmission 95 (1994), S. 179-193 
    Details
    ISSN: 1435-1463
    Keywords: Nefiracetam (DM-9384) ; phosphatidylcholine ; ethylcholine mustard aziridinium ion ; acetylcholine ; choline ; monoamine ; active avoidance response ; locomotor activity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effects of nefiracetam [DM-9384; N-(2,6-dimethyl-phenyl)-2-(2-oxo-pyrrolidinyl)acetamide] and of phosphatidylcholine on a step-up active avoidance response, locomotor activities and regional brain cholinergic and monoaminergic neurotransmitters in AF64A-treated mice were investigated. Intracerebroventricular (i.c.v.) injection of AF64A (ethylcholine mustard aziridinium ion; 8 nmol/ventricle) impaired acquisition and retention of the avoidance task, and increased vertical and horizontal locomotor activities. Regional levels of acetylcholine, noradrenaline, 3-methoxy-4-hydroxyphenylglycol (MHPG), 5-hydroxytryptamine (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) were significantly decreased and homovanillic acid (HVA) levels were increased in the hippocampus but not in the septum, cerebral cortex or striatum of AF64A-treated animals. Administration of nefiracetam (3 mg/kg, p.o.) twice daily for 9 days to AF64A-treated animals ameliorated the deficit in active avoidance response in addition to attenuating the increase in locomotor activities. In parallel with these behavioural effects, nefiracetam reversed AF64A-induced alterations in the hippocampal profiles of cholinergic and monoaminergic neurotransmitters and their metabolites. In contrast, administration of phosphatidylcholine (30 mg/kg, p.o.) twice daily for 9 days had no significant effect on the deficit in active avoidance response, despite significantly reversing the decrease in acetylcholine levels in the hippocampus. These results indicate that the effects of nefiracetam on AF64A-induced behavioural deficits are probably due to its ability to facilitate both cholinergic and monoaminergic neurotransmitter systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01271565
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  • 5
    Electronic Resource
    Electronic Resource
    Effects of nefiracetam, a novel pyrrolidone derivative, on brain monoamine metabolisms in mice (1992)
    Springer
    Journal of neural transmission 90 (1992), S. 125-136 
    Details
    ISSN: 1435-1463
    Keywords: Nefiracetam (DM-9384) ; oxiracetam ; indeloxazine ; monoamines
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effects of acute and chronic administration of nefiracetam, a pyrrolidone derivative, on monoaminergic neurotransmitter systems in the mouse hippocampus, frontal cortex, hypothalamus, and striatum were studied. The levels of monoamines and of their metabolites were measured by high performance liquid chromatography with electrochemical detection on the first, 7th, and 14th days after nefiracetam was given. The neurochemical effects of nefiracetam were compared with those of oxiracetam and indeloxazine. Acute administration of nefiracetam (10 mg/kg, po) and oxiracetam (10 mg/ kg, po) had no effect on the levels of noradrenaline (NA), dopamine (DA), or 5-hydroxytryptamine (5-HT), or on the levels of their metabolites, 3-methoxy-4-hydroxyphenylglycol (MHPG), 3,4-dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA), and 5-hydroxyindoleacetic acid (5-HIAA), in any of the regions examined. In contrast, a single dose of indeloxazine (10 mg/kg, po) decreased the levels of MHPG, DOPAC, and 5-HIAA in all regions examined. After chronic administration of nefiracetam (10 mg/kg, po, once daily), the levels of MHPG, DOPAC, and 5-HIAA were higher than control in all regions on the 14 th day only. Oxiracetam (10 mg/kg, po, once daily) similarly increased the levels of MHPG, DOPAC, and 5-HIAA in the hippocampus, frontal cortex, and striatum, but not in the hypothalamus. Conversely, indeloxazine (10 mg/ kg, po, once daily) decreased the levels of MHPG and 5-HIAA in all regions and the levels of DOPAC and HVA in the hippocampus and striatum as measured on the 7 th and 14 th days. These results show that nefiracetam has a delayed effect on brain monoaminergic metabolism, and that its effects are similar to those of oxiracetam, but clearly different from those of indeloxazine.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01250794
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  • 6
    Electronic Resource
    Electronic Resource
    Synthesis of novel polysilylenes bearing phenol groups directly bonded to Si—Si main chains for preparing Langmuir-blodgett thin films (1993)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 31 (1993), S. 3361-3370 
    Details
    ISSN: 0887-624X
    Keywords: polysilylene ; polysilane ; Langmuir-Blodget ; phenol ; thin film ; orientation ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Polysilylenes with a phenol group directly bonded to the main chain Si atom were prepared by polymerizing dichlorosilane monomers bearing phenol groups protected by t-butyldimethylsilyl ether, followed by deprotecting the silyl ether. These amphiphilic polysilanes were applied to provide oriented thin films by the Langmuir-Blodgett technique. Stable monolayers were not obtained for polysilylenes having only alkyl and aryl substituents. However, all the polysilylenes with phenol moieties provided monolayers on a water surface. These polysilylene monolayers were transferred to hydrophobic substrates by applying the Langmuir-Blodgett technique. Among these polysilylenes, only poly(n-butyl-3-hydroxyphenylsilylene) provided multilayers in which the Si—Si main chains oriented in the dipping direction. The orientation was determined by polarized UV absorption. The orientation ratio reached 0.45. © 1993 John Wiley & Sons, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1993.080311324
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