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  • 1995-1999  (8)
  • 1985-1989  (17)
  • 1
    Electronic Resource
    Electronic Resource
    Investigation of bias enhanced nucleation of diamond on silicon (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 4388-4396 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The process of bias enhanced nucleation of microwave chemical vapor deposited diamond on silicon has been extensively characterized using plasma diagnostics, scanning and transmission electron microscopy (TEM), Raman spectroscopy, and x-ray diffraction. The nucleation kinetics were measured as a function of bias voltage, methane partial pressure, and substrate temperature. The nucleation is found to be transient in character, with a delay time followed by an exponential increase in nucleation density with time, and finally a saturation. The ion flux and ion energy distribution was measured by a retarding field probe. The nucleation density was found to reach a maximum at a bias at which the ion energy distribution has a maximum of 80 eV, independent of the substrate temperature. This is taken as strong evidence that nucleation enhancement involves ion subplantation. The Raman spectra and x-ray diffraction suggests that the films during nucleation consist primarily of sp2 bonded noncrystalline carbon. The presence of the (0002) interlayer graphitic peak suggests that the carbon is primarily graphitic. The diamond nuclei form in this matrix. TEM shows mainly amorphous hillocks being formed on the substrates by bias enhanced nucleation. Diffraction patterns and high resolution TEM reveal the presence of β-SiC and also a small number of diamond particles. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.361864
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  • 2
    Electronic Resource
    Electronic Resource
    Mechanism of bias-enhanced nucleation of diamond on Si (1995)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 66 (1995), S. 3287-3289 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The nucleation of diamond on Si is enhanced for negative substrate bias of 200–250 V. We show that the ion flux is the critical factor causing the enhanced nucleation. The ion energy distribution has a maximum at about 80 eV, the optimum to subplant C ions into a-C. We propose that subplantation causes deposition of nanocrystalline graphitic C, and that diamond nucleates where the graphitic planes are locally oriented perpendicular to the surface. An atomic model is proposed that allows a matching of the diamond, graphite, and Si lattice. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.113732
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  • 3
    Electronic Resource
    Electronic Resource
    Beta-Adrenergic Blocking Drugs (1985)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Medicine 36 (1985), S. 145-164 
    Details
    ISSN: 0066-4219
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1146/annurev.me.36.020185.001045
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  • 4
    Electronic Resource
    Electronic Resource
    The role of gastric histamine release in the acid secretory response to pentagastrin and methacholine in the dog (1995)
    Springer
    Inflammation research 44 (1995), S. 327-334 
    Details
    ISSN: 1420-908X
    Keywords: Histamine ; Gastric ; Pentagastrin ; Acid secretion ; Canine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We have previously demonstrated that both pentagastrin and methacholine can stimulate histamine release from the canine stomach during short term administration of the secretagogues into the gastrosplenic artery. In this study we tested the hypothesis that gastric histamine release determines the acid secretory response to acid secretagogues. Increasing doses of pentagastrin (2, 6, and 20 ng/kg/min) and methacholine (0.1, 0.3, and 1µg/min) were infused into the gastro-splenic artery in dogs, while gastric acid output, histamine and Nτ-methyl histamine secretory rates were monitored. Histamine and Nτ-methyl histamine concentrations in plasma were measured using GC/NICI-MS. Increasing doses of pentagastrin resulted in increasing gastric output. Total histamine secretory rate expressed as the sum of histamine and Nτ-methyl histamine secretory rate showed a significant increase above basal with the two highest doses of pentagastrin. Regression analysis correlating the dose of pentagastrin to gastric acid output gave a correlation coefficient of 0.586 which was very significant. Regression analysis correlating the total histamine secretory rate to acid output gave a correlation coefficient of 0.498 which was also very significant. Increasing doses of methacholine also resulted in a dose-dependent increase in acid output. Histamine secretory rates showed a statistically significant increase above basal only at the 1µg/min infusion rate, however, the total histamine secretory rates (histamine + Nτ-methyl histamine) were no longer significant at any of the doses of methacholine. Regression analysis correlating the dose of methacholine to gastric acid output gave a correlation coefficient of 0.571 which was significant, while correlating the histamine secretory rate to acid output gave a correlation coefficient of 0.338, not significant, which decreased to 0.079 when the total histamine secretory rates were correlated to acid output. Sixty-eight min infusions of pentagastrin demonstrated a dose-dependent, pulse-like but persistent increase in histamine secretory rate above basal, while long-term infusion of methacholine gave a flat, low-grade histamine stimulation. These data suggest that for pentagastrin, both the dose of pentagastrin and the amount of histamine released determine the acid secretory response with this secretagogue, but the dose of pentagastrin correlates more strongly with acid output. During cholinergic stimulated acid output, only the dose of methacholine correlates with acid output. Thus, for cholinergic stimulated gastric acid output, histamine is not likely to be a final mediator, but for gastrin both its direct action at the parietal cell and the amount of histamine released appear to contribute to the acid secretory response.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01796263
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  • 5
    Electronic Resource
    Electronic Resource
    Neither dapsone hydroxylation nor cortisol 6β-hydroxylation detects the inhibition of CYP3A4 by HIV-1 protease inhibitors (1998)
    Springer
    European journal of clinical pharmacology 54 (1998), S. 741-747 
    Details
    ISSN: 1432-1041
    Keywords: Key words CYP3A4 ; Dapsone N-hydroxylation ; Cortisol β-hydroxylation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract Objective: This study examined the use of dapsone N-hydroxylation and cortisol 6β-hydroxylation, well accepted in vivo probes of cytochrome P4503A4 (CYP3A4) activity, on defining the effect of three HIV protease inhibitors on CYP3A4 activity. Methods: Subjects from University Hospital Infectious Disease Clinic about to be started on indinavir, and subjects from two clinical studies, one using ritonavir and the other using amprenavir, were recruited to participate in the study. Subjects received dapsone 100 mg p.o. followed by an 8-h urine collection for dapsone, dapsone N-hydroxylamine, cortisol, and 6β-hydroxycortisol concentrations before HIV protease inhibitor administration, and 3–4 weeks into receiving HIV protease inhibitors. Results: None of the HIV protease inhibitors demonstrated statistically significant alterations in dapsone recovery ratio and 6β-hydroxycortisol/cortisol ratio. In fact, with ritonavir, the dapsone recovery ratio tended to increase rather than decrease, suggesting induction. These negative results were found despite evidence of CYP3A4 inhibition by these three HIV protease inhibitors via published drug-drug interactions with drugs that are substrates for CYP3A4. Conclusions: These in vivo assays used to probe CYP3A4 activity are suboptimal, most likely because of the presence of extrahepatic sites of metabolism for both dapsone and cortisol, and multiple CYP isozymes involved in dapsone N-hydroxylation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002280050545
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  • 6
    Electronic Resource
    Electronic Resource
    The effect of aging on the pharmacokinetics and pharmacodynamics of prazosin (1996)
    Springer
    European journal of clinical pharmacology 50 (1996), S. 41-46 
    Details
    ISSN: 1432-1041
    Keywords: Key words Prazosin ; Elderly; pharmacokinetics ; age-related ; pharmacodynamics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract. Objective: The effect of age on the pharmacokinetics and pharmacodynamics of prazosin (α1 adrenoceptor blocker) was studied in 20 healthy volunteers. Patients: Ten elderly (61–81 y) and ten young (23–28 y) subjects were studied. All subjects received 1 mg of prazosin orally in a fasting state. Serial blood samples were collected for calculation of oral pharmacokinetics, and blood pressure and pulse rate were measured during blood collection. Subjects remained supine and fasting for the first three hours post drug administration, after which they were allowed to ambulate and eat. Results: The oral pharmacokinetics of prazosin were not different in the two age groups. The serum t1/2 in the elderly was 210 min while in the young group was 139 min. The AUC0−∞ in the two groups was not different. The Cmax was identical in the two groups, and the time to Cmax was 84 min in the elderly and 114 min in the young subjects. Protein binding was 93.4% in the elderly and 93.5% in the young subjects and the serum α1 acid glycoprotein concentration was not different in the two groups of subjects. Even though the pharmacokinetics of prazosin were unchanged by age, the haemodynamic effects of the drug were greater in the elderly. The fall in systolic blood pressure and mean blood pressure was significantly greater in the elderly group at multiple time points after drug administration while the change in diastolic blood pressure was equivalent in the two age groups. Despite a greater decrease in mean blood pressure in the elderly, the compensatory increase in heart rate was similar in the two age groups suggesting a difference in the baroreceptor reflex in the two age groups. Conclusion: The results of this study demonstrate that age does not alter the pharmacokinetics of oral prazosin, but the pharmacodynamic response at equivalent plasma prazosin concentration is greater in the elderly.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002280050067
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  • 7
    Electronic Resource
    Electronic Resource
    T-lymphocyte colony formation of murine thymocytes in agar contained in glass capillaries (1987)
    Springer
    Annals of hematology 55 (1987), S. 517-522 
    Details
    ISSN: 1432-0584
    Keywords: Thymocytes ; Colony formation ; Agar gel ; Glass capillaries ; Il-2
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Optimal growth conditions are presented for a new colony test with mouse thymocytes in agar contained in glass capillaries. The kinetics of colony growth and the dependence from the PHA-, Il-2-, agar- and 2-mercaptoethanol concentration are shown. The colony forming cells are identified as T-lymphocytes by usual morphology and by an indirect immunoperoxidase method using mouse anti-Thy 1.2 antibodies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00320224
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  • 8
    Electronic Resource
    Electronic Resource
    Fabrication and application of imaging holographic gratings (chirped gratings) for integrated optics (1987)
    Springer
    Optical and quantum electronics 19 (1987), S. 247-251 
    Details
    ISSN: 1572-817X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract Holographic chirped gratings with parallel grating lines have been fabricated by recording the interference structure of a plane wave and a cylindrical wave in a photoresist layer on a monomode glass waveguide. These gratings will be useful elements for the imaging of guided waves in integrated optics. A theoretical approach for treating their imaging properties is presented. The experimental results are described theoretically.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02032519
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  • 9
    Electronic Resource
    Electronic Resource
    Photoresist Bragg gratings as beam splitters and beam reflectors for integrated optical systems (1987)
    Springer
    Optical and quantum electronics 19 (1987), S. 49-58 
    Details
    ISSN: 1572-817X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract Based on the theory of coupled waves the diffraction efficiency (DE) of Bragg reflectors on planar glass waveguides is described for the case of obliquely incident waves. The coupling coefficients of the different types of mode conversion are determined both by a perturbational analysis and by fitting of the theoretical DE curves to the experimental data. Results on the fabrication and use of photoresist gratings on monomode glass waveguides as beam splitters and beam reflectors are given.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02030631
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  • 10
    Electronic Resource
    Electronic Resource
    Structure of a monoclinic polymorph of N-[4-(acetyloxy)-phenyl]acetamide, a prodrug of acetaminophen (1999)
    Springer
    Journal of chemical crystallography 29 (1999), S. 175-178 
    Details
    ISSN: 1572-8854
    Keywords: Acetaminophen prodrug ; drug polymorphism ; x-ray analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The preparation, single crystal x-ray structure and the computed powder XRD pattern of a monoclinic polymorph of N-[4-(acetyloxy)phenyl]acetamide, a prodrug of acetaminophen, are reported. The polymorph crystallizes in the space group P21/n with Z = 4 and unit cell dimensions a = 7.219(2), b = 8.015(2), c = 16.575(2) Å, β = 92.07(1)°, and V = 958.4(4) Å3. Infinite spiral molecular arrays result from intermolecular head-to-tail hydrogen bonding between the amidic H atom of one molecule and the acetoxy carbonyl oxygen atom of a 21-related molecule.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009565926282
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