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  • 1
    ISSN: 1432-1076
    Keywords: Key words: Beta-endorphin – Cerebrospinal fluid – Nucleus tractus solitarius – Sudden infant death
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. In nucleus tractus solitarius (NTS) beta-endorphin (BEND) induces bradycardia and respiratory depression which have been reported to precede death in sudden infant death (SID). Of SID victims, 50% have elevated levels of beta-endorphin immunoreactivity (BENDI) in the cerebrospinal fluid (CSF), and 50% had undetectable levels. We therefore investigated the relationship of BENDI in the CSF to BENDI levels in the NTS area. This study included SID victims (CSF from n=47, brain stem from n=16), borderline SID victims (CSF and brain stem from n=2), sudden death in childhood (CSF and brain stem from n=1), and controls (CSF from n=32, brain stem from n=11). BEND in CSF and NTS area, after extraction, was measured by radioimmunoassay. High performance liquid chromatography was used for closer identification of BENDI. We found that the SID victims divided into two subpopulations, one having a relatively high BENDI level in CSF and one having no detectable level (P〈0.01). Furthermore, an inverse relationship was found between BENDI level in CSF and BENDI level in NTS area in the SID victims (P〈0.05). We conclude that increased BENDI level in CSF is associated with low BENDI level in the NTS area in 50% of SID victims. The low BENDI level in the NTS area may be due to increased release of BEND.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-1076
    Keywords: Beta-endorphin ; Hypoxanthine ; Hypoxia ; SID
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Beta-endorphin (BEND) may induce respiratory depression. Elevated levels of beta-endorphin immunoreactivity (BENDI) in the CSF are found in children with apnoea and in about 50% of sudden infant death (SID) victims. Premortal hypoxia in SID victims has been indicated by elevated hypoxanthine (HX) levels in the vitreous humour (VH). In this study we correlated BENDI in CSF with HX in VH in SID victims (n=19) and controls (n=18). BEND in CSF was measured by RIA, and HPLC was used for identification of BENDI. HX in VH was measured by HPLC. All the SID victims had elevated levels of HX in VH. The BENDI in CSF divided the SID victims into two subpopulations (P〈0.01); one with undetectable levels (〈4.3 fmol/ml) (n=10) and one with high levels (160–400 fmol/ml) (n=9).In the SID subpopulation with high levels of BENDI in CSF,we found a correlation between BENDI in CSF and HX in VH (r=0.92). Control infants who died a stressful death, such as during heart operations (n=2), had high levels of BENDI in CSF and low levels of HX in VH. Controls who died of infections (n=11) had low levels of BENDI in CSF and elevated levels of HX in VH. Because hypoxia in itself does not increase BENDI in CSF, increased BENDI in CSF is probably not secondary to hypoxia but may be of aetiological significance. We therefore suggest that SID victims with high levels of BENDI in CSF, which correlate with the elevated levels of HX in VH, may die from premortal hypoxia possibly induced by BEND.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 14 (1967), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 16 (1969), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract— The subcellular distribution of N-acetyl-aspartate, N-acetyl-aspartyl-glutamate, N-acetyl-glutamate and glutathione (reduced) was investigated. Lactate dehydrogenase, potassium, glutamate and aspartate were employed as markers of the cytoplasmatic compartments. Fumarate hydratase and choline acetyltransferase were used as mitochondrial and synaptosomal markers respectively.Our data show that the highest concentrations of NAA, NAGA, NAAGA and glutathione were localized in the supernatant with a smaller peak in the crude mitochondrial (P2) fraction. On subfractionating P2, NAA was distributed similarly to aspartate and K+ with a peak in the synaptosome (B) fraction, while glutathione and NAAGA were localized in the mitochondrial fraction. NAA, aspartate and K+ were more readily released than glutathione and NAAGA from their particulate form on exposure to hypo-osmotic conditions.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 68 (1990), S. 1558-1562 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Carbon films were deposited by rf bias sputtering of a carbon target in argon. Bias voltage and argon pressure were varied systematically. Hardness, internal stress, density, hydrogen content, and infrared absorption were measured as functions of the preparation parameters. From the IR measurements the bond ratio of sp3 to sp2 was calculated and the total amount of hydrogen in the films was determined by elastic recoil detection. The hydrogen content was found to be much lower than for films prepared by plasma decomposition of hydrocarbons. Because the film thickness was in the range of 500 nm, the hardness was measured with an ultralow-load diamond indenter. For these measurements the indentation depth was about 60 nm. The internal stress was determined by the bending beam method. The coordination number, number density, and the filling factor were calculated from the measured values. The results have been compared to those for films deposited by plasma decomposition of hydrocarbons.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 68 (1990), S. 1018-1022 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Diamondlike a-C:H films have been deposited by decomposition of C2H2. By the combination of Brillouin scattering and the ultralow load indentation technique, the following mechanical properties of the films were studied: the microhardness H, the Young's modulus E, the shear modulus μ, and the Poisson's ratio ν. From the measured data of mass density, hydrogen concentration, and the ratio of sp3/sp2 bonds the filling factors of these films were calculated. The results show that the hardness, Young's modulus, and shear modulus of these films depend strongly on the volume concentration of voids and are directly proportional to the filling factor.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 67 (1990), S. 6772-6778 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A series of a-Si:H films has been prepared by rf sputtering in a H2-Ar gas mixture. To obtain films with different hydrogen content the hydrogen portion of the gas mixture was changed from 0% to 20%. The shear modulus μ was then measured by the frequency of the surface phonon (Rayleigh wave). The stiffness S and the ultramicrohardness H were measured by using a nanoindenter. From the shear modulus μ and the stiffness S, the Young's modulus E and Poisson's ratio ν were calculated. The intrinsic mechanical stress was measured by the bending-beam method. With increasing hydrogen content of the films, the decrease of Young's modulus, microhardness, and internal stress are observed.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 68 (1990), S. 1378-1380 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Gas evolution experiments have been performed on hydrogenated amorphous carbon (a-C:H) films prepared by plasma deposition. Two series of films are studied: in series I, C2H2 is used as a process gas at a fixed bias voltage while the gas pressure is varied, and in series II, CH4 is employed at a fixed gas pressure, and the bias voltage is changed. The results are compared to infrared absorption data and density measurements and support the presence of a void network in the amorphous material, the extent of the void network depending on the deposition conditions.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 67 (1990), S. 487-494 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Diamondlike a-C:H films have been deposited by plasma decomposition of C2 H2. 50 samples were prepared with a systematic variation of the deposition parameters: the substrate bias voltage was between −100 and −1400 V and the C2 H2 gas pressure was between 4×10−4 and 2.6×10−1 mbar. The following properties of the films were measured: the density by Rutherford backscattering, the total concentration of hydrogen by elastic recoil detection, the bonding ratio sp3 /sp2 by infrared spectroscopy, the internal stress by the bending beam method, and the hardness with a Knoop microhardness tester. It has been shown that the hardness and other mechanical properties cannot be correlated to the average carbon coordination number mc. This is because mc is calculated under the assumption of a homogenous single-phase model, which does not seem to be justified. It is demonstrated that the mechanical properties can be explained by the application of a void model.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 16 (1990), S. 510-514 
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Comparative studies were performed on the chemical composition, the microstructure, residual stress, hardness and Young's modulus of titanium nitride films, which were prepared by reactive ion beam sputtering at substrate temperatures of 77 and 300 K. The main experimental parameter of sample preparation was the N2/Ar gas flow ratio r, which determines not only the chemical composition of the film, [N]/[Ti], but also its mechanical and electrical properties. The chemical composition was investigated by AES, XPS and RBS. Microstructural data were obtained by grazing incidence x-ray diffractometry. The measurements indicate a mixed phase of Ti, Ti2N and TiN at lower r ratios and of cubic TiN at r 〉 0.05. From the integrated breadth of the diffraction lines, grain size D and strain ε were determined: 150-250 Å for D and 0.5-1.5% for ε The residual stress was measured by determining the bending of the substrate. Extraordinarily high compressive stress with pronounced maxima around stoichiometric composition was observed. The microhardness Hv and Young's modulus E were derived from the indentation loading-unloading curve, as measured with a nanoindenter. Values up to 25 GPa for Hv and up to 10 GPa for E were obtained.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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