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  • 1
    Digitale Medien
    Digitale Medien
    Recombination-enhanced Fe atom jump between the first and the second neighbor site of Fe–acceptor pair in Si (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 80 (1996), S. 6198-6203 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: We studied the recombination-enhanced Fe atom jump between the first (1st) and second (2nd) neighbor sites of Fe–Al and Fe–B pairs in Si. We first annealed specimens at 80 °C to generate Fe–acceptor pairs after doping of Fe. Concentrations of the 1st and 2nd neighbor Fe–acceptor pairs were determined by electron-spin-resonance (ESR) measurement after annealing at around 150 K under optical excitation. The concentration of the 1st neighbor pair was decreased and that of the 2nd neighbor pair was increased by the above annealing. Activation energy for the above changes was about 0.11 eV in the case of the Fe–Al pair. This is much smaller than that (0.8 eV) of thermal annealing alone. In the case of the Fe–B pair, the ESR signal of the 2nd neighbor pair could be detected due to annealing at around 160 K under optical excitation. © 1996 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.363695
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  • 2
    Digitale Medien
    Digitale Medien
    Cathodoluminescence study on dislocations in silicon (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 3253-3260 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: A study was made on the characteristics of cathodoluminescence (CL) from Si crystals with various configurations of dislocations. D3 and D4 were observed along slip lines, while D1 and D2 were found to be strong in the region where plural slip lines intersect each other. It was shown that not only Lomer–Cottrell dislocations but also jogs act as recombination centers for D1 and D2 luminescence. The spatial distributions of D1 and D2 luminescence were observed to be similar to each other, this was also true of D3 and D4. The effect of hydrogenation on CL distribution was also investigated. Contrary to the reports of other groups, no evidence was obtained on the enhancement of D line luminescence due to metal contamination. © 1996 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.361271
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  • 3
    Digitale Medien
    Digitale Medien
    Precipitation behaviors of Cu and Fe on Frank-type partial dislocations in Czochralski-grown silicon (1996)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 68 (1996), S. 214-216 
    Details
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Precipitation behaviors of Cu and Fe on Frank-type partial dislocations bounding bulk stacking faults in Czochralski-grown silicon are investigated by means of the electron beam-induced-current (EBIC) technique and transmission electron microscopy (TEM). Frank partials in a Cu-contaminated specimen do not exhibit an EBIC contrast at room temperature when the specimen is cooled slowly; however, in the Fe-contaminated specimen, they exhibit EBIC contrast at room temperature due to their Fe contamination. The TEM micrograph shows that Cu develops precipitate colonies in the region away from stacking faults and does not precipitate on Frank partials in the specimen. The results indicate that Fe impurity decorates Frank partials more easily than Cu impurity in Si. © 1996 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.116464
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  • 4
    Digitale Medien
    Digitale Medien
    Differential effects of the serotonin receptors on cultured rat cerebral cortical neurons (1997)
    Springer
    Cellular and molecular life sciences 53 (1997), S. 233-236 
    Details
    ISSN: 1420-9071
    Schlagwort(e): Key words. Serotonin; ligand-gated receptor; G-protein-coupled receptor; patch-clamp; cerebral cortical neuron.
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract. Effects of serotonin (5-HT) on cerebral cortical neurons were examined by patch clamp techniques. 5-HT produced a variety of responses such as outward (19/73 patches/neurons), slow inward (15/73 patches/neurons), fast inward (8/73 patches/neurons), and mixed currents (initially fast inward deflection followed by an outward response: 2/73 patches/neurons), with a latency of 12 sec, 15 sec, 0 sec, and 0 sec respectively, at a holding potential of −60 mV in whole-cell patches. The fast inward currents were again evoked by a selective 5-HT3 receptor agonist, 1-(m-chlorophenyl)-biguanide hydrochloride (CPBG). In the cell-attached patch clamp configuration, 5-HT inside the patch pipette elicited single channel currents with slope conductances of 42 pS and 132 pS (4/42 patches/neurons). CPBG inside the patch pipette evoked inward single channel currents with a lower slope conductance of 41 pS (3/23 patches/neurons). In contrast, application of 5-HT or a 5-HT2 receptor agonist, α-methyl-5-hydroxytryptamine-maleate, outside the patch pipette induced outward single channel currents with a major slope conductance of 140 pS (8/30 patches/neurons) or 135 pS (6/20 patches/neurons), respectively. These results indicate that the outward and fast inward currents may be mediated respectively by the 5-HT2 receptor, which is coupled to a G-protein, and by the 5-HT3 receptor, which contains the non-selective cation channel, and that the mixed type may be caused by both the 5-HT2 and 5-HT3 receptors.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/PL00000596
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  • 5
    Digitale Medien
    Digitale Medien
    Positron lifetime and 2D-ACAR studies of divacancies in Si (1995)
    Springer
    Applied physics 61 (1995), S. 65-70 
    Details
    ISSN: 1432-0630
    Schlagwort(e): 78.70 ; 61.70 ; 61.80
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract We have measured positron lifetime and Two Dimensional Angular Correlation of Annihilation Radiation (2D-ACAR) distributions of Floating-Zone grown (FZ) Si specimens containing divacancies (V2) with the definite charge states, V 2 0 , V 2 −1 or V 2 −2 from room temperature to about 10 K. These charge states are accomplished by an appropriate combination of dopant species, their concentration and irradiation doses of 15 MeV electrons. with reference to the currently accepted ionization level of divacancies. The positron lifetime of the negatively charged divacancy increases with temperature, while that of the neutral divacancy shows little change with temperature. The positron trapping rate, obtained from lifetime and 2D-ACAR measurements, increases markedly with decreasing temperature. This is found not only for the negative divacancies but also for the neutral divacancy. We need a model which explains this temperature dependence. The 2D-ACAR distribution from positrons trapped at divacancies shows nearly the same distribution for the different charge states, which differs considerably from the case of As vacancies in GaAs studied by Ambigapathy et al. We have observed a small but definite anisotropy in the distribution of trapped positrons in V 2 − using a specimen containing oriented divacancies.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01538213
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  • 6
    Digitale Medien
    Digitale Medien
    Positron lifetime and 2D-ACAR studies of divacancies in Si (1995)
    Springer
    Applied physics 61 (1995), S. 65-70 
    Details
    ISSN: 1432-0630
    Schlagwort(e): PACS: 78.70; 61.70; 61.80
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract.  We have measured positron lifetime and Two Dimensional Angular Correlation of Annihilation Radiation (2D-ACAR) distributions of Floating-Zone grown (FZ) Si specimens containing divacancies (V2) with the definite charge states, V0 2, V-1 2 or V-2 2 from room temperature to about 10 K. These charge states are accomplished by an appropriate combination of dopant species, their concentration and irradiation doses of 15 MeV electrons with reference to the currently accepted ionization level of divacancies. The positron lifetime of the negatively charged divacancy increases with temperature, while that of the neutral divacancy shows little change with temperature. The positron trapping rate, obtained from lifetime and 2D-ACAR measurements, increases markedly with decreasing temperature. This is found not only for the negative divacancies but also for the neutral divacancy. We need a model which explains this temperature dependence. The 2D-ACAR distribution from positrons trapped at divacancies shows nearly the same distribution for the different charge states, which differs considerably from the case of As vacancies in GaAs studied by Ambigapathy et al. We have observed a small but definite anisotropy in the distribution of trapped positrons in V- 2 using a specimen containing oriented divacancies.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01538213
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  • 7
    Digitale Medien
    Digitale Medien
    Nilvadipine protects low-density lipoprotein cholesterol from in vivo oxidation in hypertensive patients with risk factors for atherosclerosis (2000)
    Springer
    European journal of clinical pharmacology 56 (2000), S. 35-41 
    Details
    ISSN: 1432-1041
    Schlagwort(e): Key words Nilvadipine ; Hypertension ; Atherosclerosis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Abstract Objective: Nilvadipine, a calcium antagonist, has been shown to have antioxidant activity in vitro, but its effect on in vivo oxidation has not been assessed. The aim of this study was to investigate the antioxidant effect of this agent in vivo. The ratios of 7-keto cholestadien to cholesterol are believed to be an available marker of lipid peroxidation. Using these ratios, we have assessed the antioxidant effect of nilvadipine on low-density lipoprotein (LDL) in hypertensive patients with high risk of atherosclerosis. The risk factors of atherosclerosis may involve oxidation of LDL. Methods: Fifteen healthy subjects (seven females and eight males aged 35–72 years, mean ± SD=55.3 ± 13.8 years) and fifteen hypertensive patients (seven females and eight males aged 45–80 years, mean ± SD = 60.2 ± 11.8 years) were recruited. Patients were treated orally with nilvadipine (4 mg b.i.d.) for 4 weeks. Cholesterol oxidation levels of LDL in patients before and after nilvadipine therapy and healthy subjects were studied. Results: The ratios of 7-keto cholestadien to cholesterol in LDL of hypertensive patients before and 4 weeks after nilvadipine treatment and in healthy subjects were 6.5 ± 1.6% (mean ± SD), 3.8 ± 1.2%, and 0.2 ± 0.1%, respectively. There were significantly (P 〈 0.001) increased levels of cholesterol oxidation in LDL in patients with hypertension both before and after nilvadipine treatment compared with healthy subjects. However, there was a significantly (P 〈 0.001) decreased level of cholesterol oxidation in LDL in patients after nilvadipine treatment compared with patients before nilvadipine treatment. Conclusion: Our data showed that nilvadipine may protect LDL cholesterol from in vivo oxidation in hypertensive patients with high risk of atherosclerosis.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s002280050717
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  • 8
    Digitale Medien
    Digitale Medien
    The C677T mutation in the methylene tetrahydrofolate reductase gene increases serum uric acid in elderly men (2000)
    Springer
    Journal of human genetics 45 (2000), S. 257-262 
    Details
    ISSN: 1435-232X
    Schlagwort(e): Key words MTHFR ; Homocysteine ; Uric acid
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract A common mutation, C677T, in the methylene tetrahydrofolate reductase gene (MTHFR) reduces the activity of MTHFR and increases total homocysteine levels in plasma. Increased homocysteine levels are reportedly associated with high serum uric acid levels. The relationship between the MTHFR mutation and uric acid metabolism remains unclear, however. To investigate whether the C677T MTHFR mutation is a risk factor for hyperuricemia, we performed MTHFR genotyping and clinical laboratory determinations, including serum uric acid, in 271 elderly Japanese men (age range, 40–79 years; mean, 52.6 years). The mean uric acid levels for the C/C, C/T, and T/T genotypes were 5.67, 6.00, and 6.39 mg/dl, respectively (P = 0.012). The T/T genotype was more frequent in subjects with high uric acid levels than in those with low uric acid levels (P = 0.038). These findings suggest that the C677T MTHFR mutation contributed to higher uric acid levels in subjects enrolled in this study. In conclusion, the mutation of the MTHFR gene may be a risk factor for hyperuricemia in elderly men.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s100380070037
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