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  • 1
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Biochemistry 23 (1984), S. 197-203 
    ISSN: 1520-4995
    Source: ACS Legacy Archives
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 92 (2002), S. 1555-1563 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Photoacoustic spectroscopy is an absorption spectroscopy technique that is currently used for low-level gas detection and catalyst characterization. It is a promising technique for chemical analysis in mesoscale analysis systems because the detection limit scales favorably with miniaturization. This work focuses on the scaling properties of photoacoustic spectroscopy, and on the miniaturization of gas-phase photoacoustic detection of propane in a nitrogen ambient. The detection system is modeled with a transmission line analogy, which is verified experimentally. The model includes the effects of acoustic leaks and absorption saturation. These two phenomena degrade the performance of the photoacoustic detector and must be controlled to realize the scaling advantages of photoacoustic systems. The miniature brass cells used to verify the model employ hearing aid microphones and optical excitation from a mechanically chopped, 3.39 μm He–Ne laser, transmitted into the cells with an optical fiber. These cells are able to detect 10 ppm of propane in nitrogen (a signal level of ∼1 Pa/W). We also describe the development of a miniaturized photoacoustic system formed by microfabrication. In this case, the pressure-driven deflection of the detection membrane is measured optically. These systems show that photoacoustic detection may be inappropriate for systems with large variations in gas concentration because of absorption saturation and changing gas acoustic properties. Nevertheless, photoacoustic spectroscopy is a promising technique for the analysis of dilute mixtures in miniature chemical systems. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 117 (2002), S. 3711-3714 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The optical response of Li4+ and Li7+ exhibits three large maxima at photon energies between 1.9 and 3.6 eV, on which a fine structures could be resolved that has a peak to peak distance of about 30–40 meV. A high level ab initio calculation of Li4+ shows that this feature is due to vibrational structure of the excited electronic state. It is pointed out that the lifetime of the excited states exhibits a dramatic shortening with increasing particle size. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 98 (1993), S. 6102-6120 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The resonant two-photon ionization spectra of the first benzene–Arn (n≤8) clusters are interpreted in the light of a model calculation, including local energy minima determinations and Monte Carlo simulations. Based on spectral shift information, two types of structures are distinguished: the argon cluster either only solvates one side of the substrate molecule or covers simultaneously both sides. The "wettest'' structures are assigned to sandwich-type forms for n≤4 and to clamshell-type forms beyond. Such a 2D–3D transition in the n=5–8 size range is shown to be specific to small substrate size. In the one-sided forms, the argon cluster geometry is strongly influenced by the presence of the Bz molecule since it adopts a quasiplanar geometry, more or less tightly bound to the substrate depending on its size: the small argon clusters exhibit two types of complexation sites (c and s forms) which are simultaneously visited (surface decoupling) even at low temperature (∼7 K). As the size increases, the c form becomes prevalent and the surface decoupling becomes inhibited. At n=8 a 2D–3D transition is observed: beyond the n=7 species, characterized by a caplike close-packed structure, the one-sided conformers disappear in favor of bridged forms. Additional results on the ionization behavior of the one-sided species show regular variation of the ionization potential with the cluster size.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: An apparatus is described for the measurement of photo processes in mass-selected cluster ions. A gridless reflectron type of time-of-flight (TOF) mass spectrometer is used to select an ion of known mass. The selected ion is photoexcited with a pulsed dye laser. The charged fragments are mass separated in a second linear TOF. A new combination of reflectron and linear TOF is described, which allows one to measure the complete photofragment mass distribution over an arbitrary large mass range for each laser shot, which was not possible earlier. It is discussed how clusters with different temperatures can be prepared. The first measurement of a temperature-dependent effect for mass-selected free cluster ions is presented.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Inorganic chemistry 32 (1993), S. 5053-5057 
    ISSN: 1520-510X
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 96 (1992), S. 2404-2406 
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Amyloid β-peptide (Aβ)1−42 oligomers have recently been discussed as intermediate toxic species in Alzheimer's disease (AD) pathology. Here we describe a new and highly stable Aβ1−42 oligomer species which can easily be prepared in vitro and is present in the brains of patients with AD and Aβ1−42-overproducing transgenic mice. Physicochemical characterization reveals a pure, highly water-soluble globular 60-kDa oligomer which we named ‘Aβ1−42 globulomer’. Our data indicate that Aβ1−42 globulomer is a persistent structural entity formed independently of the fibrillar aggregation pathway. It is a potent antigen in mice and rabbits eliciting generation of Aβ1−42 globulomer-specific antibodies that do not cross-react with amyloid precursor protein, Aβ1−40 and Aβ1−42 monomers and Aβ fibrils. Aβ1−42 globulomer binds specifically to dendritic processes of neurons but not glia in hippocampal cell cultures and completely blocks long-term potentiation in rat hippocampal slices. Our data suggest that Aβ1−42 globulomer represents a basic pathogenic structural principle also present to a minor extent in previously described oligomer preparations and that its formation is an early pathological event in AD. Selective neutralization of the Aβ globulomer structure epitope is expected to have a high potential for treatment of AD.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Oxford, UK and Boston, USA : Blackwell Publishing Ltd
    Child and adolescent mental health 5 (2000), S. 0 
    ISSN: 1475-3588
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Psychology
    Notes: Body Dysmorphic Disorder (BDD) is an excessive preoccupation with an imagined, or real, slight defect in normal physical appearance. The disorder, which usually begins during adolescence, tends to be chronic, and probably is much more common than is usually thought. This review presents an overview of the available scientific literature of BDD. It provides information about historical aspects, epidemiology, clinical features, aetiology, and instruments for assessing BDD. The relationship of BDD with other psychiatric disorders such as depression, obsessive-compulsive disorders, anxiety disorders, schizophrenia, eating disorders and personality disorders is discussed. Aetiological theories, including psychological and neurobiological explanations, are reviewed. Finally, psychopharmacological and psychotherapeutic treatment approaches are presented with special regard to treatment with serotonin-reuptake inhibitors, behavioural therapy and cognitive-behavioural therapy.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Using a whole-cell binding procedure with long incubations at low temperature and subsequent acid stripping, we have characterized an atypical endothelin (ET) receptor in primary rat cortical astrocyte cultures. We found the following: (a) no competition for 125I-ET-1 binding by the ETA antagonists BQ-123 and LU 135252 or the ETB agonist IRL 1620; (b) weak competition by the ETB antagonist BQ-788 and by the predominant ETB ligand ET-3; (c) potent synergistic competition of ETA and ETB ligands in combination for 125I-ET-1 binding; (d) potent competition of ET-1 with any of the radioligands used, 125I-ET-1, 125I-IRL 1620, and [3H]BQ-123; (e) lack of competition of IRL 1620 and BQ-123 with the respective other radioligand; (f) shifting of the amount of acid-strippable 125I-ET-1 binding from 20 to 80% by ETB ligands and to 4% by ETA ligands; and (g) as a control, typical ETA and ETB binding characteristics of the RAT-1 fibroblast and the U373MG astrocytoma cell line, respectively, under our assay conditions. The unusual binding properties of astrocytic ET receptors described in this study appear to be the result of several binding sites in the receptor for different ET ligands or ligand epitopes.
    Type of Medium: Electronic Resource
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