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  • 2000-2004  (8)
  • 1985-1989  (10)
  • 1
    Electronic Resource
    Electronic Resource
    A pulsed supersonic entrainment reactor for the rational preparation of cold ionic complexes (2000)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 71 (2000), S. 4431-4434 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We describe an ion source for the efficient preparation of cold ion-molecule complexes, X−⋅M. The method relies on condensation of solvent molecules, M, onto argon-solvated ions, X−⋅Arm, where the X−⋅Arm species are formed in a primary expansion and the molecular partner, M, is interfaced to this flow in the hydrodynamic region by supersonic entrainment. This hybrid "supersonic afterglow" reactor provides a clean synthetic approach for both bare and argon-solvated complexes, where the latter are particularly useful since their structures can be characterized by "nanomatrix" infrared predissociation spectroscopy. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1326931
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  • 2
    Electronic Resource
    Electronic Resource
    Electron-beam-induced optical memory effects in GaN (2002)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 80 (2002), S. 2675-2677 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Metastable effects in unintentionally doped GaN films grown on SiC substrates have been investigated using cathodoluminescence (CL). Memory effect patterns produced optically are observed in CL images. An electron beam can also produce memory effect patterns and the resulting changes in the luminescence spectra are quite similar for either optical or electron-beam-induced patterns. CL spectra reveal that the yellow luminescence at 2.2 eV increases significantly with little change in the band-edge emission in both cases. Samples that do not exhibit optically induced memory effects are also investigated and do not exhibit electron-beam-induced patterns, either. Monochromatic CL images at 540 and 365 nm confirm the similarity of optically and electron-beam-induced memory effects based on changes in luminescence spectra. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1469222
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  • 3
    Electronic Resource
    Electronic Resource
    Recombination of Br−2 photodissociated within mass selected ionic clusters (1988)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 88 (1988), S. 6200-6210 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Photofragmentation studies of mass selected Br−2⋅(CO2)n, n≤24, cluster ions are presented. The heterogeneous cluster ions are synthesized in a supersonic expansion crossed with an electron beam. These ionic clusters are mass analyzed in a time-of-flight mass spectrometer prior to photodissociation of the Br−2 absorber in the cluster. Mass analysis of the ionic photofragments shows that in some cases the photodissociated Br−2 has recombined and in other cases a Br atom has escaped from the cluster. The branching ratio for recombination depends on both the size of the initial cluster ion and the photodissociation wavelength. The photofragmentation data are consistent with a recombination mechanism dominated by attractive forces in the smaller clusters and repulsive interactions in the larger clusters.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.454458
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  • 4
    Electronic Resource
    Electronic Resource
    Argon predissociation and electron autodetachment spectroscopy of size-selected CH3NO2−⋅Arn clusters (2001)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 115 (2001), S. 10718-10723 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Photodetachment spectra of CH3NO2−⋅Arn clusters in the mid-IR are dominated by three strong resonances. These are assigned to autodetaching (AD) C–H stretching vibrational transitions in the valence (as opposed to dipole-bound) form of the molecular anion on the basis of a H/D isotopic substitution study and their solvation dependence. The AD resonances disappear promptly upon addition of the third argon atom, while the resonant structure appears in the action spectrum for formation of CH3NO2− photoproducts for n≥2. The strong argon solvation dependence of the photoproducts is traced to the rapidly changing endoergicity of the electron loss channel due to the differential solvation behavior of the valence anion relative to the neutral. We discuss a statistical limit for this competition, and introduce an intramolecular vibrational energy redistribution mediated AD mechanism unique to polyatomic anions. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1418251
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  • 5
    Electronic Resource
    Electronic Resource
    Photofragmentation of (CO2)+nB: Simple energy dependence for the number of neutrals ejected, 13〈n〈26 (1985)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 82 (1985), S. 5288-5289 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Ionic photofragmentation patterns of (CO2)+n, 2〈n〈26, are determined at 1064, 650, and 532 nm, and are found to be remarkably simple. The average number of neutral CO2 molecules lost increases smoothly with cluster size, approaching a constant value that depends linearly on the photon energy. A model for involving sequential loss of CO2 monomers is indicated, and the average CO2-cluster bond energy is found to be constant at 4.9 kcal/mol for n〉13.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.448605
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  • 6
    Electronic Resource
    Electronic Resource
    BaI product state distribution from the reaction Ba+CF3I (1986)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 85 (1986), S. 5723-5732 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Under single-collision beam–gas scattering conditions the Ba+CF3I→Bal+CF3 reaction has been studied using laser induced fluorescence to detect the BaI X 2∑+ product. The resulting BaI C 2Π–X 2∑+ excitation spectrum has a complex appearance owing to the similarity of the upper and lower state rotational constants, causing a reversal in band shading, and owing to a predissociation in the upper state, causing a break off in the fluorescence of high vibrational levels in each spin-orbit subband. From the predissociation onset an upper bound of 78.5±0.5 kcal/mol is placed on the BaI bond energy. The vibrational population distribution is shown to be bell shaped, peaking near v‘=50, and accounts for most of the available energy. The average energy appearing in BaI rotation decreases with increasing BaI vibrational excitation. The BaI rotational distribution has a width comparable to that of the vibrational distribution.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.451533
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  • 7
    Electronic Resource
    Electronic Resource
    Immunity in the Female Lower Genital Tract and the Impact of HIV Infection (2001)
    Oxford, UK : Blackwell Science Ltd
    Scandinavian journal of immunology 54 (2001), S. 0 
    Details
    ISSN: 1365-3083
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: This study investigates the distribution of immunocompetent cells in the ectocervix, and cytokine and immunoglobulin (Ig) levels in cervicovaginal secretions to determine whether they are altered in asymptomatic human immunodeficiency virus (HIV) infection. Ectocervical biopsies from 10 HIV+ and 10 presumed HIV-ve women were studied by immunocytochemistry. Levels of Igs in cervicovaginal secretions were quantified by radial immunodiffusion (RID) and cytokine levels by ELISA. HIV+ women had significantly increased numbers of CD8+ lymphocytes resulting in reversal of the CD4:CD8 ratio. There was a significant increase in the proportion of activated CD8+ HLA-DR+ and CD4+ HLA-DR + lymphocytes, but not in CD8+ TIA-1+ cells. The epithelium of the cervix from HIV+ subjects showed a significant increase in both numbers of macrophages (CD68+) and proportions of activated macrophages (CD68+ HLA-DR+) compared to normal. The stroma contained increased proportions of inductive (D1+) and suppressive (D1+ D7+) macrophages but a decrease in effector phagocyte (D7+) proportions and Langerhans' cells. Significantly lower tumour necrosis factor (TNF)-α levels were observed in cervicovaginal secretions from HIV+ subjects. IgG levels were 4 times higher and IgM levels twice higher in cervicovaginal secretions from HIV+ women, compared to results from normal subjects. These results suggest a response within the CD8+ cells in HIV+ women, yet these cells may have a low cytolytic capacity. The raised proportions of HLA-DR+ and D1+ CD4+ macrophages could act as antigen-presenting cells (APC) for CD4+ CD45RO+ lymphocytes, and represent a local acquired response. However, the close juxtaposition of these cells offers the potential for them to act as a local reservoir of virus and promote its proliferation. The increase of IgG over sIgA in secretions of HIV+ subjects provides evidence suggesting a dysregulation of local humoral immunity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-3083.2001.00927.x
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  • 8
    Electronic Resource
    Electronic Resource
    The Cellular Response Associated with Cervical Intraepithelial Neoplasia in HIV+ and HIV– Subjects (2002)
    Oxford, UK : Blackwell Science Ltd
    Scandinavian journal of immunology 56 (2002), S. 0 
    Details
    ISSN: 1365-3083
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: This study investigates local alterations in T-cell and macrophage subsets that occur in cervical epithelial neoplasia (CIN), in the presence and absence of human immunodeficiency virus (HIV) infection. Ectocervical biopsies from 10 women with CIN who were infected with HIV, and 10 women with CIN but no HIV infection were studied by immunocytochemistry.Significantly increased proportions of activated CD8+ T cells were seen in all CIN biopsies, and these proportions were further increased in the presence of HIV infection. Levels of CD8+TIA-1+ cells were particularly increased in the CIN+HIV+ group. There was a lack of expression of CD28 on the CD8+ cells of the epithelium of CIN+HIV+ samples. A significant reduction in the proportion of epithelial inductive D1+ macrophages and an increase in D1+D7+-suppressive cells were observed in the CIN+HIV+ cohort.The lack of expression of CD28 on the CD8+ cells of the epithelium of CIN+HIV+ samples in combination with the reduced CD4+ T-cell numbers seen in the presence of HIV infection may contribute to the development of higher grade CIN in this susceptible group. This may be aggravated by the reduction in the D1+ epithelial inductive macrophages, which might reflect recruitment of more suppressive D1+D7+ cells. This would further compromise the ability of the local T-cell system to respond to antigens and thus contribute to the development of neoplasia at this site. These results suggest that the increase in activated CD8+ T cells is a consequence rather than a cause of CIN.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-3083.2002.01118.x
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  • 9
    Electronic Resource
    Electronic Resource
    Physiology (communication arising) The ventilatory response to hypoxia (2002)
    [s.l.] : Nature Publishing Group
    Nature 419 (2002), S. 686-686 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Gozal et al. reply We do not challenge the 'classic' theory of peripheral-chemoreceptor-mediated HVR. However, this offers no insight into the mediators of the time-domain components of HVR, such as ventilatory short-term potentiation (VSTP). VSTP is critical to ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/419686b
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  • 10
    Electronic Resource
    Electronic Resource
    Defects of Complex I and Complex IV in Skeletal Muscle from Patients with Chronic Progressive External Ophthalmoplegia (1986)
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 488 (1986), S. 0 
    Details
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1749-6632.1986.tb54430.x
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