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  • Articles: DFG German National Licenses  (14)
  • 1995-1999  (11)
  • 1970-1974  (2)
  • 1960-1964  (1)
  • 11
    Electronic Resource
    Electronic Resource
    Springer
    Journal of sol gel science and technology 4 (1995), S. 67-73 
    ISSN: 1573-4846
    Keywords: photostability of laser-dye ; inorganic-organic matrix ; optical solid material ; fluorescence decay ; mobility of dye
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The laser dye, 4-dicyanomethylene-2-methyl-6-p-dimethylaminostyryl-4H-pyran (DCM) was incorporated in various inorganic-organic host matrices by the sol-gel technique. The photostability of the DCM-doped materials under CW argon laser irradiation was investigated. The absorption of DCM monomer ar 480 nm decreased with increasing irradiation time and was accompanied by an increase in the absorption at 352 nm by inactive photoproducts. Photostability was estimated by measuring the decay rates of DCM fluorescences in different host matrices. The rates exhibited two components; a rapid decay within the first several tens of seconds followed by a slower luminescence decay. The rapid decay depended upon the DCM content in the matrix while the slow decay component was related to the mobility of the DCM in the different matrices. The silica host matrix containing phenyl and a small amount of epoxy groups exhibited the best photostability of the materials examined.
    Type of Medium: Electronic Resource
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  • 12
    Electronic Resource
    Electronic Resource
    Springer
    The journal of membrane biology 18 (1974), S. 379-397 
    ISSN: 1432-1424
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary The macrocyclic polyethers 4′-methylbenzo-15-crown-5 (15C5) and 4′-methylbenzo-18-crown-6 (18C6) as well as the corresponding crown polymers and crown-styrene copolymers were used as carriers for the transport of sodium and potassium picrate or the corresponding chlorides across a stirred, chloroform membrane. The observation of pronounced bathochromic shifts in the optical spectra of picrate salts on increasing the interionic ion pair distance could be utilized in determining the nature and structure of the migrating species. These species were found to be ion pair crown complexes of at least two kinds, viz., crown-complexed tight ion pairs and crown-separated ion pairs. The feasibility to thus identify the detailed structure of the migrating ionic entity is important as solvents of low polarity such as chloroform or hexane have been used as liquid membranes to represent the interior of biomembranes. The structure of the ion pair is expected to be an important consideration in correlating properties such as membrane potentials or cation selectivities with ionic distribution equilibria. Ion pair extraction equilibrium constants were determined in the H2O−CHCl3 system for the various crown species. The values for 18C6 with sodium and potassium picrate are nearly the same as those for the corresponding polymers. The same was found with 15C5 and sodium picrate; but the potassium forms, in addition to a 1∶1 complex, a 1∶2 complex with 15C5, making the corresponding polymer a more effective extracting agent. The ionic distribution data were interpreted in terms of the salt partition coefficients and the complex formation constants of the ion pair crown complexes in chloroform. The salt migration across the liquid membrane was found to be controlled by the diffusion of the ion pair complex in the chloroform, the extraction equilibrium across the interphase being rapidly established. The thickness of the diffusion layer adjacent to the water-chloroform interphase was estimated to be 50 μ. The ratios of the salt fluxes under otherwise identical conditions were found to be governed by the extraction equilibrium constants, the selectivity ratio for the potassium-to-sodium picrate with 18C6 being 118. This ratio, which was also determined for other crown species, was found to be anion dependent.
    Type of Medium: Electronic Resource
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  • 13
    ISSN: 1573-6776
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract In the absence of an external substrate, H 2 was evolved in Rhodovulum sulfidophilum under light-anaerobic conditions, along with degradation of poly(3-hydroxybutyrate) (PHB). Cells grown with succinate as a sole carbon source accumulated only a small amount of PHB compared with that in cells grown with a multiple substrate consisting of a mixture of four organic acids. Unlike PHB-containing cells, PHB-deficient cells did not evolve H in the absence of an external substrate. Nitrogenase activity was expressed while no hydrogenase activity was detected during the incubation of PHB-containing cells. These results suggest that intracellular PHB serves as a substrate for the H evolution catalyzed by nitrogenase when an external substrate is lacking.
    Type of Medium: Electronic Resource
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  • 14
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Archives of Insect Biochemistry and Physiology 28 (1995), S. 291-309 
    ISSN: 0739-4462
    Keywords: juvenile hormone ; methoprene ; pyriproxyfen ; fat body ; locust ; binding protein ; receptor ; Chemistry ; Food Science, Agricultural, Medicinal and Pharmaceutical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Juvenile hormone (JH) binding components from the fat body of the African migratory locust were analyzed in a search for a potential nuclear JH receptor. Biosynthetically prepared 10R[3H]JH III gave a high proportion of specific binding to isolated nuclei and extracted proteins; data obtained with the JH analogs, [3H]methoprene and [3H]pyriproxyfen, on the other hand, were obscured by abundant non-specific binding. The vast majority of the high affinity JH III binding activity present in cytosolic and nuclear extracts was due to a high molecular weight JH binding protein (JHBP) which has previously been identified in locust hemolymph. This protein has several chromatographic forms which interfered in the search for a nuclear JH receptor. When specific antiserum was used to remove JHBP from nuclear extracts, a novel JH binding activity (NBP) was detected. NBP could be separated from JHBP by precipitation with ammonium sulfate. NBP displayed a high affinity for JH III (Kd = 0.25 nM) and JH I and JH II competed strongly for JH III binding, whereas methoprene and pyriproxyfen showed apparent competition when present in 1,000-fold excess. NBP was present in nuclear extracts at approximately 25,000 sites per cell; levels were similar in male and female locusts and were not greatly affected by the presence or absence of JH. The characteristics of NPB make it a strong candidate for a nuclear JH receptor. © 1995 Wiley-Liss, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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