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  • 1
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A new levitation apparatus coupled to a synchrotron-derived x-ray source has been developed to study the structure of liquids at temperatures up to 3000 K. The levitation apparatus employs conical nozzle levitation using aerodynamic forces to stably position solid and liquid specimens at high temperatures. A 270 W CO2 laser was used to heat the specimens to desired temperatures. Two optical pyrometers were used to record the specimen temperature, heating curves, and cooling curves. Three video cameras and a video recorder were employed to obtain and record specimen views in all three dimensions. The levitation assembly was supported on a three-axis translation stage to facilitate precise positioning of the specimen in the synchrotron radiation beam. The levitation system was enclosed in a vacuum chamber with Be windows, connections for vacuum and gas flow, ports for pyrometry, video, and pressure measurements. The vacuum system included automatic pressure control and multi-channel gas flow control. A phosphor screen coupled to a high-resolution video microscope provided images of the x-ray beam and specimen shadow which were used to establish the specimen position. The levitation apparatus was integrated with x-ray diffractometers located at X-6B and X-25 beamlines at the National Synchrotron Light Source. X-ray structural measurements have been obtained on a number of materials including Al2O 3, Ni, Si, Ge, and other metallic and ceramic materials in the liquid state. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 67 (1995), S. 3456-3458 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have used a simple approach to fabricate buried InGaAs/InP quantum wires with widths down to 15 nm. Combining high resolution electron beam lithography and selective wet chemical etching only the InP cap layer of an InGaAs/InP quantum well is locally removed. InGaAs surface quantum wells are formed in the etched parts of the samples, where the energy band discontinuity of the quantum well is replaced by the high vacuum barrier. Therefore a lateral potential barrier is induced, which confines the carriers to the InP covered wire regions. In addition, the lateral potential can be strongly increased by a selective thermal intermixing step. The luminescence spectra of the wires show significant lateral quantization effects with energy shifts up to 13 meV and high quantum efficiencies up to room temperature. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 71 (1997), S. 1379-1381 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Palladium is known to exhibit an acceptor state at EC−0.22 eV in n-type Si and a donor state at EV+0.31 eV in p-type Si. We have identified a third level at EV+(0.140±0.005) eV and attribute it to the double donor state of substitutional Pd. The Pd level positions are very similar to the corresponding levels for Pt. The double donor states of both metals show an electric field dependence of the emission rates and a thermal activation of the hole capture cross sections. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 70 (1997), S. 1584-1586 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The midgap level in platinum doped n-type silicon, which was proposed to be the dominant recombination center, is identified as a platinum-hydrogen complex. Hydrogenation of the samples is achieved by wet-chemical etching at room temperature. Defect profiles, determined by deep level transient spectroscopy, clearly associate the level with the concentration profile of atomic hydrogen. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 103 (1995), S. 274-280 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The structure of the ground and lowest two excited states of H2NO have been determined in large scale configuration interaction calculations using a multiconfiguration self-consistent description of the molecular orbitals. These treatments are based on a systematic building of the correlation contribution which has been designed to account for the characteristics of the nitroxide group. This approach shows that the aminoxyl functional group is more than a three electron group shared by two atoms, but, in fact, a nine electron entity. Our best estimate of the geometry of the ground electronic state, obtained after second-order configuration interaction using a large basis of atomic natural orbitals, is pyramidal. However, since the potential depth between 0° and 40° is lower or of the same order of magnitude as the estimated inversion frequency, the conclusion that this molecule behaves like a planar system is totally justified. The structure of the excited (n−π*) and (π−π*) states have been determined and the transitions energies are in accordance with the experimental results on the highly substituted stable nitroxide radicals. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 99 (1995), S. 16351-16356 
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 375 (1995), S. 637-637 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] SIR - Infants born to HIV-infected mothers acquire maternal antibody trans-placentally, rendering the interpretation of serological assays difficult. Secure diagnosis of perinatal infection should include investigation both of a maternal sample and of two or more infant ...
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Company
    Nature biotechnology 13 (1995), S. 271-275 
    ISSN: 1546-1696
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: [Auszug] We have developed a chromosomal integration system for gene transfer into the extreme thermophile Thermus flavus. The system relies on integration at the site of leuB (3-isopropylmalate dehydrogenase) which was cloned from T. flavus. The leuB gene was insertionally inactivated in vitro with a ...
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract A search for an abundant and economical source of isoflavones, particularly genistein, led to the discovery that the erythromycin-producing organism Saccharopolyspora erythraea also produces this promising new cancer-prevention agent. Erythromycin fermentation is a large-scale, soybean-based process used world-wide for the commercial production of this medically important antibiotic. Results from this study indicate that genistin (the glucoside form of genistein), which is added to the fermentation in the soybean media, was converted to genistein through the action of a β-glucosidase produced by the organism. Genistein was co-extracted with erythromycin from the fermentation broth, then separated from erythromycin during the second step of the purification process for the production of erythromycin.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1432-1262
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé. Le but de cette étude est de déterminer la fiabilité des potentiels évoqués corticaux après stimulation électrique du canal anal. Des potentiels évoqués corticaux ont été enregistrés chez 243 patients se plaignant de douleurs périnéales (28 patients), d'impuissance (55 patients) d'incontinence fécale (52 patients), d'incontinence urinaire (30 patients), de constipation (49 patients), et chez 29 patients neurologiques, par stimulation du sphincter anal externe et du pénis ou du clitoris. La reproductibilité inter- et intra-observateurs a étéétudiée par codage des interprétations données par trois observateurs à l'occasion de deux évaluations distinctes. L'influence des caractéristiques de l'enregistrement et des données cliniques a été déterminée. Afin d'étudier le rôle de l'opérateur, cinq opérateurs ont investigué les patients mais un seul était particulièrement entraîné pour cette investigation. L'interprétation des courbes d'enregistrement par les observateurs était peu reproductible dans 15% des cas, dépendant du temps écoulé entre les deux lectures et dépendant de la qualité de l'enregistrement. L'interprétation de la réponse cérébrale après la stimulation anale est dépendante de l'observateur et influencée par sa connaissance des données cliniques. Ceci a également été observée avec la mesure des potentiels corticaux évoqués après stimulation du pénis ou du clitoris, toutefois dans une moindre mesure. La méthode du potentiel évoqué cérébral est également dépendante de l'opérateur, particulièrement après la stimulation anale. Lorsque une étude des potentiels corticaux évoqués par stimulation périnéale est nécessaire en pratique clinique, il semble logique de préférer la technique des potentiels corticaux évoqués par stimulation du pénis ou du clitoris, car ils semblent plus faciles à obtenir que ceux observés après stimulation anale si les investigateurs ne sont pas particulièrement familiers avec les méthodes électrophysiologiques et, car les premiers sont davantage opérateurs et observateurs dépendants.
    Notes: Abstract. The aim of this study was to assess the reliability of cortical evoked potentials after electrical stimulation of the anal canal. Cortical evoked potentials were recorded on 243 patients presenting with perineal pain (28 patients), impotence (55 patients), anal incontinence (52 patients), urinary continence (30 patients), constipation (49 patients), and on 29 neurological patients, by stimulating the external anal sphincter and penis (or clitoris). The inter- and intra-observer reproducibility was studied by coding recordings interpreted by three different observers on two separate occasions. The influence of recording characteristics and clinical data were assessed. To study operator dependence, five operators investigated the patients. Only one of them was well trained in this technique. The interpretation of the coded curves by the observers was poorly reproducible in about 15% of cases, depending on time between the two readings and the quality of recordings. The interpretation of cerebral responses after anal stimulation were observer-dependent and influenced by the knowledge of clinical data. This was also observed with cortical evoked potentials after electrical stimulation of the penis or clitoris, but to a lesser extent. The cerebral evoked potentials method was also operator-dependent, mainly after anal stimulation. When a study of cortical evoked potentials by perineal stimulation is needed in clinical practice, it seems logical to prefer cortical evoked potentials by penile or clitoral stimulation as they seem easier to obtain than those evoked by anal stimulation if the investigators are not well trained for the performance of electrophysiological studies as the former are much less operator- and observer-dependent.
    Type of Medium: Electronic Resource
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