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  • 1
    ISSN: 1432-8798
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The extraction and purification of gangliosides from brains of animals infected with the scrapie agent was evaluated by scaling-down a large-scale procedure currently used with bovine brains. Inactivation experiments employed hamster brains infected with the 263 K strain of scrapie. Residual infectivity was determined at different points of the procedure and in the final preparation by an in vivo animal bioassay. The efficacy of single steps, which included chemicals or physical techniques known to affect the viability of the scrapie agent, was verified by spiking experiments where known amounts of infectivity were added just before each single step. Infectivity was significantly diminished at early stages of the purification, and no infectivity was detected in the final preparation containing purified gangliosides. The significant reduction of infectivity at intermediate steps and the total absence of detectable infectivity in the final product confirmed that a combination of heat and exposure to sodium hydroxide, even in the presence of organic solvents, completely inactivated the scrapie agent.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We present a thermokinetic model together with new experimental results for the scattering of large argon clusters off a graphite surface. Both angular and time-of-flight distributions are shown for a large range of surface temperatures, incidence angles, and incident cluster sizes. A quantitative comparison between the proposed thermokinetic model and our measurements allows one to interpret most of the experimental results as due to thermal evaporation of very small fragments from their parent clusters gliding along the surface. The coefficient of tangential velocity conservation cF and the local temperature Tlocal of the evaporating fragments have been determined quantitatively. Although the investigated parameters were varied over a large range, Tlocal remains essentially constant around (140 ± 20) K. The coefficient cF turns out to be approximately (0.80 ± 0.05) independent of surface temperature and incident cluster size for all incidence angles larger than 40°. It increases, however, rapidly to 1.4 when the incidence angle is reduced to 20° suggesting a substantial transfer from normal to tangential kinetic energy. For high enough surface temperatures, incident cluster sizes, and incident angles, both experimental time-of-flight (TOF) and angular distributions show the appearance of a grazing exit angle component attributed to large cluster fragments leaving the surface before total evaporation.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We present a complete apparatus for molecule-surface interaction studies. Three UHV chambers are connected together allowing preparation, characterization, transfer, and experimental investigations with well-defined surface samples under ultrahigh-vacuum conditions. A chopped, supersonic molecular beam with well-controlled profile enters the main UHV chamber where it is scattered by the sample under study. Detection systems have been designed to measure angular and time-of-flight distributions and rotational populations of beam particles scattered off the surface sample giving access to the energy exchange between the internal degrees of freedom of the scattered molecules and the surface. The characteristics of our apparatus are reported and experimental tests for nitrogen and argon molecular beams scattered off a graphite surface are shown.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0952-3499
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: A functional role for Nerve Growth Factor (NGF) in the peripheral nervous system is well-documented, but a similar case for NGF in the central nervous system remains to be established. One approach to answering this question would be the availability of high-affinity monospecific Fab fragments obtained against NGF. In the present studies we describe the preparation and characterization of such Fab fragments from anti-mouse NGF polyclonal antibodies. Following their purification by the use of a NGF Sepharose-coupled affinity column, the Fab fragments were examined for biological competence in several ways. In vitro, the anti-Fab fragments blcoked the neuronotrophic activity of NGF, as measured by the survival of chicken embryonic day 8 dorsal root ganglion neurons. In vivo, these Fab fragments, when administered systemically to neonatal rats, produced a decrease of noradrenaline levels in two sympathetically innervated organs, the heart and the spleen. These findings suggest that affinity purified Fab fragments of anti-NGF antibodies can be a useful tool for studying the physiological function of NGF in the nervous system.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1434-6079
    Keywords: 36.40.+d
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A method for the determination of average cluster size in supersonic beams is presented. Based on angular distribution broadening of the beams caused by passing through a buffer gas, this method is well suited for in situ determination of the mean cluster size when the apparatus contains a movable detector with sufficient spatial resolution. The shape and width of the beam profile after scattering by a buffer gas are evaluated theoretically as functions of buffer gas pressure and atom-cluster collision cross-section. Experimental results are presented for an argon beam, yielding average cluster sizes between 300 and 7000 atoms depending on the stagnation pressure. Simple criteria to assess the applicability of the method to a given experimental situation are discussed. The average cluster sizes determined in this work agree quite satisfactorily with previously published values for similar beam generation conditions.
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  • 6
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 93 (1990), S. 8228-8234 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: A simple four component lattice model is used to reproduce qualitatively phase behavior of nonaqueous microemulsions. In microemulsions where glycerol and propylene glycol replace water, 2(underbar)-3-2¯ phase transitions are observed as the glycerol content in the polar organic mixture increases. The model predicts such phase behavior and reproduces the effect of oil solvophobicity and the surfactant solvophilic–lipophilic balance. In addition, temperature insensitive phase behavior is observed in these nonaqueous mixtures and is predicted in the model. The results are used to propose possible molecular interaction mechanisms which would account for the microemulsion phase behavior. The model is compared with a similar model developed for water microemulsions and the differences are cast in light of the different molecular interactions which occur between propylene glycol, water, and nonionic surfactants.
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  • 7
    ISSN: 1432-1173
    Keywords: Schlüsselwörter: Bilaterale lineare Sklerodermie en coup de sabre – Begleitsymptome ; Key words: Bilateral linear scleroderma en coup de sabre – Associated anomalies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Abstract. Bilateral linear frontoparietal scleroderma en coup de sabre is an extremely rare form of localized linear scleroderma. In this paper the case of a 35-year-old woman with bilateral linear temporoparietal en coup de sabre is presented. The manifestations that can be associated with linear scleroderma and the serologic abnormalities it envolves are briefly discussed.
    Notes: Zusammenfassung. Die bilaterale lineare Sklerodermie en coup de sabre ist eine extrem seltene Form der lokalisierten bandförmigen Sklerodermie. Der Fall einer 35jährigen Patientin mit bilateraler linearer temporoparietaler Sklerodermie en coup de sabre wird vorgestellt. Die möglicherweise auftretenden Begleitsymptome und serologischen Befunde bei linearer Sklerodermie werden kurz erläutert.
    Type of Medium: Electronic Resource
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