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  • 1
    Digitale Medien
    Digitale Medien
    s.l. : American Chemical Society
    Analytical chemistry 26 (1954), S. 1566-1572 
    ISSN: 1520-6882
    Quelle: ACS Legacy Archives
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    s.l. : American Chemical Society
    The @journal of organic chemistry 31 (1966), S. 2426-2427 
    ISSN: 1520-6904
    Quelle: ACS Legacy Archives
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 1475-1482 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: An improved Monte Carlo model for ionized-impurity scattering is developed and used to calculate majority- and minority-electron mobilities in silicon. The model includes scattering cross sections derived from phase-shift analysis, implementation of the Friedel sum rule, and a simple phenomenological model for multiple-potential scattering. This model provides a very good fit to experiment using a single adjustable parameter. Electron mobilities in n- and p-type Si are calculated and fit to experimental data at 300 and 77 K. Experimental results for Si of μn(NA)/μn(ND) ≈ 2 at 300 K are reproduced and a value of 3 〈 μn(NA)/μn(ND) 〈 4 is predicted at 77 K.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 1483-1488 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: An improved Monte Carlo (MC) model for ionized impurity scattering developed in a previous work [L. E. Kay and T.-W. Tang, J. Appl. Phys. 70 1475 (1991)] is used to perform a comprehensive study of majority- and minority-electron mobilities in the Si1−xGex material system for both strained and unstrained cases. This investigation includes calculation of low-field mobilities for wide ranges of doping and Ge mole fraction at both 300 and 77 K as well as high-field studies. A significant improvement in mobility (up to 50%) is observed for transport perpendicular to the growth plane in strained Si1−xGex as compared to the unstrained case. The magnitude of the improvement is dependent on doping (both concentration and type) and germanium content, and is somewhat larger at 77 K. High-field MC simulations show that some strained-mobility enhancement remains even at an electric field of 100 kV/cm. These studies also suggest there is a temperature-dependent Ge content for which mobility is maximized at higher dopings.
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 55 (1990), S. 0 
    ISSN: 1471-4159
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: The appearance of μ-, δ-, and k-opioid receptors was examined in primary cultures of embryonic rat brain. Membranes prepared from striatal, hippocampal, and hypothalamic neurons grown in dissociated cell culture each exhibited high-affinity opioid binding sites as determined by equilibrium binding of the universal opioid ligand (-)-[3H]bremazocine. The highest density of binding sites (per mg of protein) was found in membranes prepared from cultured striatal neurons (Bmax= 210 ± 40 fmol/mg protein); this density is approximately two-thirds that of adult striatal membranes. By contrast, membranes of cultured cerebellar neurons and cultured astrocytes were devoid of opioid binding sites. The opioid receptor types expressed in cultured striatal neurons were characterized by equilibrium binding of highly selective radioligands. Scatchard analysis of binding of the μ-specific ligand [3H]D-Ala2,N-Me-Phe4,Gly-ol5-enkephalin to embryonic striatal cell membranes revealed an apparent single class of sites with an affinity (KD) of 0.4 ± 0.1 nM and a density (Bmax) of 160 ± 20 fmol/mg of protein. Specific binding of (-)-[3H]bremazocine under conditions in which μ- and δ-receptor binding was suppressed (k-receptor labeling conditions) occurred to an apparent single class of sites (KD= 2 ± 1 nM;Bmax= 40 ± 15 fmol/mg of protein). There was no detectable binding of the selective δ-ligand [3H]D-Pen2,d-Pen5-enkephalin. Thus, cultured striatal neurons expressed μ- and k-receptor sites at densities comparable to those found in vivo for embryonic rat brain, but not δ-receptors.
    Materialart: Digitale Medien
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  • 6
    Digitale Medien
    Digitale Medien
    s.l. : American Chemical Society
    Analytical chemistry 22 (1950), S. 760-763 
    ISSN: 1520-6882
    Quelle: ACS Legacy Archives
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 7
    Digitale Medien
    Digitale Medien
    s.l. : American Chemical Society
    Analytical chemistry 24 (1952), S. 726-732 
    ISSN: 1520-6882
    Quelle: ACS Legacy Archives
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 8
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 37 (1981), S. 0 
    ISSN: 1471-4159
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Abstract: Primary astrocytes were cultured from the forebrains of 1-day-old rats. Immunofluorescence microscopy showed that approximately 80% of the cells were positive for glial fibrillary acidic protein (GFAP) and 〉80% were stained with an antiserum to the molecular weight 58,000 fibroblast intermediate filament protein (vimentin). Gel electrophoresis of Triton-insoluble cytoskeleton preparations from these cultures revealed three major bands having molecular weights of 58,000, 51,000, and 42,000, together with some prominent lower-molecular-weight species. The protein of molecular weight 51,000 was not present in preparations from fibroblasts. Each of the three major astrocyte proteins was subjected to limited proteolysis, while two of the proteins were cleaved by cyanogen bromide. The electrophoretic peptide patterns of the 58,000 protein were similar to those of vimentin isolated from NIL-8 fibroblasts, and the patterns of the 51,000 protein were similar to those of GFAP isolated from rat spinal cord. The patterns of the protein of molecular weight 42,000 resembled those of muscle actin. Rocket immunoelectrophoresis showed that the 51,000 astrocyte protein reacted with an antiserum to bovine GFAP, but the 58,000 and 42,000 proteins failed to react. We conclude that the major proteins of cytoskeleton preparations from cultured primary astrocytes are vimentin (58,000), GFAP (51,000), and actin (42,000), and that our data show no obvious structural relationship among them.
    Materialart: Digitale Medien
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  • 9
    ISSN: 1471-4159
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Neuromelanin is a dark brown pigment present at high concentrations in dopaminergic neurones of the human substantia nigra (SN). Early electron microscopic examinations of neuromelanin fine structure revealed a significant neutral lipid component; however, the identity of this lipid has remained unknown. Here we show that the lipid component of neuromelanin pigment derived from human SN is the polyisoprenoid dolichol. Established methods were used to isolate the pigment from the SN of 32 brains and the lipid fraction was recovered in high purity and yield. Using reversed-phase HPLC, atmospheric pressure chemical ionization mass spectrometry, and 1H- and 13C-NMR techniques, we showed that the neuromelanin dolichol contained 17–23 isoprenoid units. Dolichol accounted for 14% of the mass of neuromelanin pigment; low levels of other hydrophobic compounds were detected (e.g. ubiquinone-10, α-tocopherol and cholesterol together accounted for 〈 0.5% of the neuromelanin lipid mass). This is the first time that dolichol has been identified in such a physiological setting and significantly advances our understanding of neuromelanin pigment structure and biosynthetic pathways. Furthermore, these studies identify a potential novel role for the isoprenoid pathway in the regulation of neuromelanin function and neurodegeneration within the SN.
    Materialart: Digitale Medien
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  • 10
    ISSN: 1471-4159
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: We investigated the effects of neuromelanin (NM) isolated from the human substantia nigra and synthetic dopamine melanin (DAM) on neuronal and glial cell lines and on primary rat mesencephalic cultures. Lactate dehydrogenase (LDH) activity and lipid peroxidation were significantly increased in SK-N-SH cells by DAM but not by NM. In contrast, iron-saturated NM significantly increased LDH activity in SK-N-SH cells, compared with 100 mg/mL ETDA-treated NM containing a low concentration of bound iron. DAM, but not NM, stimulated hydroxyl radical production and increased SK-N-SH cell death via apoptotic-like mechanisms. Neither DAM nor NM induced any changes in the glial cell line U373. 3H-Dopamine uptake in primary rat mesencephalic cultures was significantly reduced in DAM- compared with NM-treated cultures, accompanied by increased cell death via an apoptosis-like mechanism. Interestingly, Fenton-induced cell death was significantly decreased in cultures treated with both Fenton reagent and NM, an effect not seen in cultures treated with Fenton reagent plus DAM. These data are suggestive of a protective role for neuromelanin under conditions of high oxidative load. Our findings provide new evidence for a physiological role for neuromelanin in vivo and highlights the caution with which data based upon model systems should be interpreted.
    Materialart: Digitale Medien
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