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  • 1
    Electronic Resource
    Electronic Resource
    Quasi-elastic Raman scattering and free volume in isotropic pressure-densified atactic poly(methyl methacrylate) glasses (2000)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 112 (2000), S. 1020-1028 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We have made a series of isotropic pressure-densified atactic poly(methyl methacrylate) (PMMA) glasses with densities ranging from 1.1823 g/cm3 to 1.1963 g/cm3, in order to investigate how the glassy dynamics, measured by Raman scattering in the frequency range of 0.1–10 THz, depends on the thermomechanical history of the glasses. In particular, we investigate whether there is a correlation between the strength of the fast relaxation dynamics and the free-volume characteristics, such as the average free-volume size and the free-volume fraction. The fast relaxation strength is deduced from the quasielastic light scattering (QES) intensity; the free-volume size is measured with positron annihilation lifetime spectroscopy (PALS); and the free-volume fraction is determined from pressure–volume–temperature (PVT) data and the Simha–Somcynsky equation-of-state (EOS) theory. Our temperature-dependent Raman and PALS measurements show that both the QES intensity and the ortho-positronium (o-Ps) lifetime increase smoothly with the temperature. On the other hand, the relaxation strength of the densified glasses at room temperature is, within experimental error, independent of the density, whereas both the o-Ps lifetime from PALS and the free volume fraction from the PVT data decrease significantly with pressure densification. We therefore conclude that the fast relaxation intensity cannot be explained on the basis of free-volume quantities, contrary to a recently suggested correlation between the QES intensity and the free volume [V. N. Novikov et al., J. Chem. Phys. 107, 1057 (1997)]. On the other hand, the observed behavior is consistent with another recently suggested model [V. N. Novikov, Phys. Rev. B 58, 8367 (1998)] which attributes the fast relaxations to vibration anharmonicity. Moreover, we show that the measured increase in the refractive index of the pressure-densified glasses fits the Lorentz–Lorenz equation and compares well to predictions of the relative change in refractive index with formation pressure from our own as well as published PVT data. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.480625
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  • 2
    Electronic Resource
    Electronic Resource
    Improved automated extraction and separation procedure for soil lipid analyses (2004)
    Oxford, UK; Malden, USA : Blackwell Science Ltd
    European journal of soil science 55 (2004), S. 0 
    Details
    ISSN: 1365-2389
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Analysis of soil lipids may contribute to an improved understanding of atmosphere to soil carbon fluxes, soil organic matter source differentiation and pollutant accumulation. Soil lipids, mostly originating from plants and microorganisms, have traditionally been analysed by non-automated extraction and separation methods, which produce several lipid fractions, operationally defined by polarity. Here we present a combination of fast, automated and reproducible techniques, adopted from organic geochemical studies, for preparative separation of individual soil lipid fractions with increasing polarity. These techniques involve commercially available instruments, including accelerated solvent extraction and a two-step automated medium-pressure liquid chromatography procedure. The method yields eight lipid fractions consisting of five fractions fully amenable to gas chromatography/mass spectrometry (GC/MS) (aliphatic hydrocarbons, aromatic hydrocarbons, ketones, alcohols, carboxylic acids), and three fractions of highly polar or high molecular weight compounds (bases, very long-chain wax esters (C40+), high polarity compounds) that were not measurable with GC/MS under standard conditions. We tested the method on five agricultural soils. Results show that (i) mass recoveries for the individual fractions are reproducible, (ii) within individual fractions compound distribution patterns are reproducible, as demonstrated for alkanes and carboxylic acids, and (iii) individual fractions represent distinct and clean compound classes, free of interfering substances detectable by GC/MS. Thus, automated separation can be a fast, effective and reproducible procedure for fractionation of complex mixtures of soil lipids into clean compound classes, directly suitable for a variety of molecular (e.g. GC/MS) and isotopic characterizations (e.g. gas chromatography coupled with isotope ratio monitoring mass spectrometry or accelerator mass spectrometry).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1351-0754.2004.00601.x
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  • 3
    Electronic Resource
    Electronic Resource
    Polarized luminescence in CdS/ZnSe quantum-well structures (2000)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 77 (2000), S. 85-87 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The photoluminescence from type II CdS/ZnSe quantum-well structures is found to be polarized with respect to the 〈110〉 directions with polarization degrees up to 20%. The absolute polarization direction is related to the interface bond directions in samples with differently prepared interfaces. The observations are explained by the detailed analysis of the epitaxial growth process and polarization sensitive luminescence experiments. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.126885
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  • 4
    Electronic Resource
    Electronic Resource
    Cell surface presentation of recombinant (poly-) peptides including functional T-cell epitopes by the AIDA autotransporter system (2000)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS immunology and medical microbiology 27 (2000), S. 0 
    Details
    ISSN: 1574-695X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: For the efficient surface presentation and release of virulence factors especially pathogenic Gram-negative bacteria have developed several distinct secretion mechanisms. An increasing number of pathogens in various species employs a mechanism denoted the ‘autotransporter’ pathway. This pathway is characterised by an outer membrane translocator module representing the C-terminal domain of the transported protein itself. An intriguing potential application of such systems involves the transport and surface expression of recombinant proteins or peptides, like e.g. the presentation of antigens for the generation of live oral vectors as vaccine carriers. Here we report on the incorporation of heterologous (poly-) peptides in permissive sites of the translocator module of the adhesin-involved-in-diffuse-adherence (AIDA) autotransporter system. We demonstrate the presentation of the B subunit of the heat labile enterotoxin of Escherichia coli (LTB) as well as of functional T-cell epitopes of Yersinia enterocolitica heat-shock protein 60 (Y-hsp60) on the surface of E. coli.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-695X.2000.tb01446.x
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  • 5
    Electronic Resource
    Electronic Resource
    Buchbesprechungen (1964)
    Springer
    Colloid & polymer science 198 (1964), S. 101-111 
    Details
    ISSN: 1435-1536
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01499465
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  • 6
    Electronic Resource
    Electronic Resource
    Defect generation in polycrystalline Cu(In,Ga)Se2 by high-energy electron irradiation (2000)
    Springer
    Applied physics 70 (2000), S. 677-680 
    Details
    ISSN: 1432-0630
    Keywords: PACS: 61.80.Fe; 61.82.Fk; 84.60.Jt
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract. We investigate the degradation of ZnO/CdS/ Cu(In,Ga)Se2 heterojunction solar cells for space applications and the defect generation in polycrystalline Cu(In,Ga)Se2 thin films by irradiation with 1-MeV electrons with fluences φe up to φe=5×1018 cm-2. Notable degradation of the solar cell performance starts at fluences of φe=1017 cm-2 where the open circuit voltage decreases by about 5% while short circuit current and fill factor remain essentially unaffected. Thus, Cu(In,Ga)Se2 solar cells withstand electron fluences which are higher by one order of magnitude or more when compared to other technologies. A model describes the absolute open circuit voltage loss considering the increase of space charge recombination by electron irradiation-induced defects. Defect analysis by admittance spectroscopy shows that acceptor defects with an energy distance of approximately 300 meV from the valence band are generated at a rate γ=0.017 (±0.01) cm-1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003390050014
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  • 7
    Electronic Resource
    Electronic Resource
    Nasal Epithelial Permeation of Thymotrinan (TP3) Versus Thymocartin (TP4): Competitive Metabolism and Self-Enhancement (2000)
    Springer
    Pharmaceutical research 17 (2000), S. 222-228 
    Details
    ISSN: 1573-904X
    Keywords: nasal absorption ; peptide absorption ; nasal metabolism ; aminopeptidases
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. To investigate concentration dependent permeabilities andmetabolism kinetics of thymotrinan (TP3) versus thymocartin (TP4)in nasal epithelium in vitro. Methods. Excised bovine nasal mucosa was used as an in vitro model.Permeabilities were studied in a diffusion chamber, metabolism kineticsin a reflection kinetics set-up. Studies were performed at various TP3and TP4 concentrations. The 3H-mannitol flux was measured to monitorjunctional permeability. Potential Ca2+-complexation was investigatedusing a Ca2+-selective electrode. Results. Permeability of TP3 was negligible at 0.1 and 0.2 mM andincreased drastically above 0.4 mM up to ∼2 × 10−5 cm s−1. In thepresence of 2 mM TP4 the TP3 permeabilites were significantly above(∼4 × 10−5 cm s−1) the level of TP3 without TP4, and TP3 metabolismwas totally inhibited. TP3 and TP4 showed a significant concentrationdependent effect on the permeability of 3H-mannitol. Ahyperosmolarity effect of the peptide solutions was excluded. Transepithelialelectrical resistance (TEER; ∼30 Ω cm2) was unchanged by either TP3 orTP4. At 1 mM TP3 the mucosal-to-serosal permeability was four timeshigher than serosal-to-mucosal, indicating enzyme polarization. Inreflection kinetics studies, TP3 degradation was slightly higher on themucosal than on the serosal side. TP3 and TP4 followed the samenon-linear metabolism kinetics. Conclusions. Increase in permeability at high TP concentrationsinvolves competitive enzyme saturation combined with self-enhancedparacellular permeation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007529716926
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  • 8
    Electronic Resource
    Electronic Resource
    Zur Identität der aus Thioschwefelsäure mit Dichlordisulfan und aus Thioschwefelsäure mit salpetriger Säure hergestellten Tetrasulfandisulfonate und zur Existenz eines „Saueren“ Tetrasulfan-disulfonats (1964)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 330 (1964), S. 179-187 
    Details
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The product prepared following the method of GOEHRING and FELDMANN from H2S2O3 and S2Cl2 is not a „spectrum“ of different salts as stated by WEITZ and BECKER, but really K2S6O6, which is also prepared from H2S2O3 and HNO2. Tetrasulfane-disulfonate does not only exist in the neutral form K2S6O6, but also in a „acid“ form with a part of the potassium - nonstoichiometrically - replaced by H+. The two forms have different shape and X-ray spectra.
    Notes: Bei dem nach GOEHRING und FELDMANN aus H2S2O3 und S2Cl2 dargestellten Produkt handelt es sich nicht, wie von WEITZ und BECKER angegeben, um ein „Spektrum“ verschiedener Salze, sondern um einheitliches K2S6O6, wie es auch aus H2S2O3 und HNO2 erhalten wird. Tetrasulfan-disulfonat existiert neben der neutralen Form K2S6O6 noch in einer „saueren“ Form, bei der ein Teil des Kaliums - nichtstöchiometrisch - durch H+ ersetzt ist. Die beiden Formen unterscheiden sich in Aussehen und Röntgenspektrum voneinander.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19643300310
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  • 9
    Electronic Resource
    Electronic Resource
    Versuche zur Trennung von Sulfan-disulfonaten mit Hilfe von Anionenaustauschern (1964)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 330 (1964), S. 188-194 
    Details
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The separation of sulfane-disulfonates, sulfite and thiosulfate by anion-exchangers has been studied. Whereas K2S6O6 is decomposed on the column, the salts K2S3O6, K2S4O6 and K2S5O6 may be separated quantitatively.
    Notes: Die Trennung von Sulfan-disulfonaten, Sulfit und Thiosulfat mit Anionenaustauschern wird untersucht. Während K2S6O6 auf der Säule zu rasch zerfällt, lassen sich die Salze K2S3O6, K2S4O6 und K2S5O6 quantitativ voneinander trennen.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19643300311
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  • 10
    Electronic Resource
    Electronic Resource
    Thiolyse von Sulfurylchlorid (1964)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 330 (1964), S. 130-140 
    Details
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The reaction of hydrogen sulfide with sulfuryl chloride in the ratio 2:1 leads in benzene solution to hydrogen chloride, water, sulfur, and disulfur monoxide, S2O, which is surprisingly stable under the prevailing conditions. The reaction of sulfuryl chloride with liquid hydrogen sulfide leads to the formation of sulfanes and chlorosulfanes, respectively, besides other products, depending on the molar ratio H2S:SO2Cl2.
    Notes: Schwefelwasserstoff reagiert mit Sulfurylchlorid beim molaren Einsatz 2:1 in benzolischer Lösung unter Bildung von Chlorwasserstoff, Wasser, Schwefel und Dischwefelmonoxid S2O, das unter den herrschenden Reaktionsbedingungen überraschend stabil ist. Mit flüssigem Schwefelwasserstoff bildet SO2Cl2 im Unterschuß u. a. Sulfane, im Überschuß Chlorsulfane.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19643300304
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