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  • 1
    Electronic Resource
    Electronic Resource
    High-excitation phenomena in doped III–V semiconductors (1984)
    Springer
    Czechoslovak journal of physics 34 (1984), S. 402-402 
    Details
    ISSN: 1572-9486
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01590080
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  • 2
    Electronic Resource
    Electronic Resource
    The effect of perturbedk-selection and gap shrinkage on the optical transitions in III–V semiconductors (1980)
    Springer
    Czechoslovak journal of physics 30 (1980), S. 381-387 
    Details
    ISSN: 1572-9486
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Optical transitions in direct semiconductors are governed according to simple one-electron treatment by ak-selection rule, which in doped or mixed crystals is but lifted to some extent (Δk) caused by 1) shallow impurities, 2) isoelectronic impurities or 3) alloy scattering. Values of Δk for these mechanisms are given and the implications for line shapes of optical spectra are discussed. Furthermore, as to the position of lines in the optical spectra of highly doped or highly excited crystals, gap shrinkage effects have to be considered, three main mechanisms of which can be distinguished: 1) Quadratic response of the band edges with respect to the fluctuating potential of the (screened) impurities, 2) polaron effects and 3) carrier exchange and correlation effects. Results of theoretical calculation are compared with experimental findings for GaAs and GaP. The practical importance of gap shrinkage effects for gain measurements and for the operation of (Ga, Al) As laser diodes is pointed out. From the Coulomb interaction of the carriers an additional mechanism for the lifting of thek-selection rule (especially valid for pure, but excited semiconductors) can be derived (plasmon coupling): Estimations show that the simplek-selection rule is almost never fulfilled within the energy range of emission spectra and that these spectra can be well explained simply assuming no-k-selection even for pure direct material.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01596092
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  • 3
    Electronic Resource
    Electronic Resource
    Effect of methylprednisolone on experimental noncardiogenic pulmonary edema (1981)
    Springer
    Intensive care medicine 7 (1981), S. 121-124 
    Details
    ISSN: 1432-1238
    Keywords: Glucocorticoid ; Adult respiratory distress syndrome ; Posttraumatic pulmonary insufficiency ; Lung water ; Monocrotaline ; Pulmonary circulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Methylprednisolone, 30 mg/kg body weight, was given to dogs 30 min and 4 h after injection of monocrotaline to produce noncardiogenic pulmonary edema. Control animals received monocrotaline but not corticosteroids. After 6 h the steroid-treated animals demonstrated significantly better gas exchange and significantly less pulmonary edema. A possible mechanism of this beneficial effect of steroids is inhibition of complement-leukocyte interactions which may mediate pulmonary microvascular injury. The results lend some support to the clinical practice of short-term pharmacologic doses of steroids in noncardiogenic pulmonary edema.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01738614
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  • 4
    Electronic Resource
    Electronic Resource
    Separation of unmodified α-amino acid enantiomers by reverse phase HPLC (1980)
    Springer
    Chromatographia 13 (1980), S. 677-685 
    Details
    ISSN: 1612-1112
    Keywords: Ligand-exchange chromatography ; Reversed phase chromatography, amino acids ; Racemates resolution, amino acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A novel chiral phase system is presented for the resolution of unmodified α-amino acid racemates which is composed of a reverse phase packing coated with N-alkyl-L-hydroxyproline (where alkyl is n-C7H15-, n-C10H21- and n-C16H33-) and a hydro-organic eluent containing copper(II)acetate. The factors controlling retention and enantioselectivity such as concentration of Cu(II)ion and pH of the eluent, addition of NH4Ac to the eluent, type and content of organic solvent of hydro-organic eluent and column temperature were examined. The extremely high enantioselectivity observed (α up to 16) is assumed to be caused by a three site sorbate-sorbent interaction involving bidentate coordination of two amino acids to a Cu(II)ion and hydrophobic attractions between hydrocarbon side chains of amino acids and the n-octadecyl groups of the support. The efficiency and selectivity of the system permits resolution of up to 7 racemic amino acids into enantiomers within 35 minutes on a conventional HPLC apparatus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02303437
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  • 5
    Electronic Resource
    Electronic Resource
    Monomeric vs. polymeric bonded iminodiacetate silica supports in high-performance ligand-exchange chromatography (1983)
    Springer
    Chromatographia 17 (1983), S. 200-204 
    Details
    ISSN: 1612-1112
    Keywords: Liquid chromatography ; Chemically bonded silica ; Metal-complexing ligands
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The synthesis of monomeric and polymeric bonded iminodiacetate-groups on silica supports is described. The polymeric support offers advantages over the monomeric, such as (i) preparation is much simpler, (ii) higher surface concentration of functional groups can be achieved without loss of efficiency and (iii) hydrolytic stability. Cu2+ loaded supports were examined for their kinetic performance, in particular for the C-parameter of the Knox equation, and for their hydrolytic stability. Calculation of the surface coverage shows that only a rather thin polymeric layer is formed; this is in agreement with the results of the kinetic performance. The retention of α-amino acids on the Cu2+ loaded polymeric support demonstrates its use in HPLEC.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02290557
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  • 6
    Electronic Resource
    Electronic Resource
    Thinlayer-chromatography — Column liquid chromatography: Partners or competitors? (1984)
    Springer
    Chromatographia 18 (1984), S. 46-46 
    Details
    ISSN: 1612-1112
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02279466
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  • 7
    Electronic Resource
    Electronic Resource
    Comments on the use of alumina in HPLC (1984)
    Springer
    Chromatographia 18 (1984), S. 47-48 
    Details
    ISSN: 1612-1112
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02279467
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  • 8
    Electronic Resource
    Electronic Resource
    Optimisation of fast protein separations on non-porous silica-based strong anion exchangers (1993)
    Springer
    Chromatographia 37 (1993), S. 603-607 
    Details
    ISSN: 1612-1112
    Keywords: Anion exchange chromatography ; Protein separation ; Non-porous support ; Polymeric stationary phase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The adsorbed coating technology using various vinylpyrrolidone-vinylimidazole copolymer compositions was carried out on 1.7 μm non-porous monodisperse silica. It was shown that the retention properties and the loading capacity for bovine serum albumin (BSA) increases with the amount of vinylimidazole in the copolymer composition. The retention behavior of various proteins as a function of the salt composition in the eluent has been applied to find the optimal conditions for the synthesis of the anion-exchange stationary phase. The suitability of these supports for the fast separation of biological molecules is demonstrated. The best resolution and the highest speed in protein analysis was obtained by using an anion exchanger of low capacity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02274109
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  • 9
    Electronic Resource
    Electronic Resource
    A model for polybutadiene coatings on porous silica (1993)
    Springer
    Chromatographia 35 (1993), S. 403-409 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Reversed phase packings ; Polybutadiene coating ; Polymer coatings
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Non-wetting viscous liquids such as oligobutadiene prefer “active” sites such as pores during the process of physisorption. Thus, polybutadiene (PBD) coatings on porous silica do not result in a homogeneous polymer film but in an inhomogeneous loading where the bulk polymer is mainly sited in the pores of the silica. An increasing polymer loading leads to increasingly filled pores instead of a thicker polymer film. We cannot exclude the possibility that most of the surface is covered at least with a thin polymer film since the chromatographic behaviour is relatively good for polypeptides, which are highly susceptible to the silanol groups of silica.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02278594
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  • 10
    Electronic Resource
    Electronic Resource
    Packing meterials with surface barriers, controlled distribution and topography of ligands for sample clean-up and analysis of biologically active solutes in HPLC (1991)
    Springer
    Chromatographia 31 (1991), S. 507-511 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Restricted access packings ; Packings with surface barriers ; Sample clean-up of biologically active analytes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Various types of, so-called, restricted access packings have been developed for sample clean-up and analysis of biologically active solutes by means of HPLC. The unique feature of these packings is that they prevent the access of matrix components such as protein whilst selectively retaining the drug components and their metabolites. This results from the fact that the particles of the packings possess a surface barrier for large solutes at the external or internal surface area and exhibit a controlled gradient in the chemical surface composition. They are grouped, according to their particle structures, into internal-surface reversed phases (ISRP), shielded hydrophobic phases (SHP), semi-permeable surfaces (SPS), dual zone phases (DZP) and mixed functional phases (MFP). The structural characteristics and the chromatographic properties of these packings are reviewwed, especially with regard to their use in the assaying of drugs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02262398
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