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  • Column liquid chromatography  (4)
  • Polymer and Materials Science  (3)
  • 65.50 + m  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Thermodynamic properties of the spin-Peierls transition in CuGeO3 (1995)
    Springer
    The European physical journal 98 (1995), S. 167-169 
    Details
    ISSN: 1434-6036
    Keywords: 65.50 + m ; 75.10.Jm ; 75.50.Ee
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We present an investigation of the spin-Peierls transition atT SP=14.5 K in polycrystalline CuGeO3 through specific-heat and thermal-expansion measurements. Clear second-order phase-transition anomalies are found in both properties atT SP, although only a small entropy of S≈0.1 Rℓn2 is released at the transition. Most of the entropy is released atT SP〈T〈150 K, where the temperature dependence of the magnetic contribution to the specific heat as well as the thermal expansion exhibit extrema atT *≈40 K. These are caused by one-dimensional antiferromagnetic fluctuations along the Cu chains, possibly accompanied by structural fluctuations. Using Ehrenfest's relation, a hydrostatic pressure coefficient (∂T SP/∂p)p→0 ≈ (0.45±0.06) K/kbar is derived.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01324522
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  • 2
    Electronic Resource
    Electronic Resource
    New polymer coated anion-exchange HPLC-phases: Immobilization of poly (2-hydroxy, 3N-ethylenediamino) butadiene on silica and alumina (1987)
    Springer
    Chromatographia 23 (1987), S. 435-441 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Anion-exchange stationary phases ; Polymer coating ; Cross-linking
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary PHEB=POLY(2-hydroxy, 3N-ethylenediamino)butadiene has been synthesized. This unsaturated pre-polymer can be immobilized on different, preferably inorganic supports of suitable porosity such as silica or alumina by cross-linking. Weak anion-exchange phase are obtained. Such phases do not have the disadvantages of organic polymeric phases, regarding pressure stability and swelling by solvent influence. The ion-exchange capacity and the retentivity of IE-separations can deliberately be varied via the thickness of the cross-linked polymer layer. Alumina can also be coated with PHEB applying the same cross-linking procedure. Such phases exhibit an exceptional chemical stability even when operated with mobile phases at very high pH-values. Separations of excellent selectivity are achieved for inorganic anions, as well as with mixtures of aliphatic and aromatic free acids also including hydroxy- (mono- or poly)carboxylic acids.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02311821
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  • 3
    Electronic Resource
    Electronic Resource
    HPLC-separation of enantiomers using quinine, covalently bonded to silica as stationary phase (1988)
    Springer
    Chromatographia 25 (1988), S. 265-271 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Chiral phases ; Polymer coating ; Quinine substituted polysiloxanes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Stationary phases for chiral separations have been synthesized by chemical modification of porous small particle silica using new procedures of fixation of the chiral moiety. So called pre-polymers of the methylpolysiloxane polysiloxane type are immobilized on silica surfaces by different procedures. These pre-polymers are substituted by chiral groups. Their synthesis is done externally i.e. not in-situ on the support surface. The immobilization on the silica surface is achieved by crosslinking and/or by chemical bonding. Anchor groups within the pre-polymer (e.g. SiH) as well as on the silica surface (SiOH) give rise to the chemical bonding therewith. Chiral phases with quinine as the chiral moiety were obtained which show high separation efficiency as well as chemical stability, in addition to the enantiomeric selectivity required for the separation of certain types of aliphatic and aromatic alcohols.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02324699
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  • 4
    Electronic Resource
    Electronic Resource
    Characterization of some commercial poly (styrene-divinylbenzene) copolymers for reversed-phase HPLC1 (1987)
    Springer
    Chromatographia 23 (1987), S. 341-349 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Cross-linked polystyrene ; Characterization of surfaces
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The properties of the poly(styrene-divinylbenzene) copolymers PRP-1 and PLRP-S have been studied by infrared spectroscopy and chromatographic techniques. The following results were obtained: PRP-1 and PLRP-S are spectroscopically very similar. Their surfaces are chemically neither homogeneous nor stable during use. Retained nonpolar solutes should be eluted with a mobile phase containing tetrahydrofuran. Uncharged acids and anions can be chromatographed without difficulty. Cations of amines should be chromatographed only with a mobile phase of low pH. Uncharged amino-alcohols cannot be chromatographed without the addition of a competitor.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02316180
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  • 5
    Electronic Resource
    Electronic Resource
    Poly(vinylpyrrolidone)-coated silica: A versatile, polar stationary phase for HPLC (1986)
    Springer
    Chromatographia 21 (1986), S. 573-582 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Polyvinylpyrrolidone-coated silica gel ; Separation of polar compounds ; Separation of proteins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Poly(vinylpyrrolidone) (PVP) is immobilized on both, small- and large-pore silicas by thermal treatment, γ-radiation, or peroxide initiated polymerization. The hydrolytic stability of such a highly polar stationary phase significantly exceeds that of a comparable phase prepared by the chemical reaction of silica with a pyrrolidone ethyl dimethylchlorosilane silanization reagent. The properties of the different PVP-silicas are evaluated by elemental analysis, spectroscopy, and chromatography. Columns of PVP-silica packings can be used in several modes: a) under normal-phase conditions as a polar bonded stationary phase, b) under reversed-phase conditions, for the separation of organic proton-donor and hydrogen-bonding compounds, c) for the aqueous size exclusion chromatography of proteins, and d) with salt gradients for the hydrophobic interaction chromatography of proteins. The minimum observable reduced plate-height of PVP-silica columns is about 3. Double-layer polymer coating experiments using PVP-silica covered with poly(methyloctadecylsiloxane) have been performed to study diffusion and shielding effects of different polymer layers in the stationary phase. Depending on separation conditions, one or the other polymer governs the retention process. A mixed selectivity was observed in a reversed phase mode with acidic eluents.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02311839
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  • 6
    Electronic Resource
    Electronic Resource
    Experimentelle Untersuchung des statistischen Größeneinflusses im Dauerschwingversuch an ungekerbten Stahlproben (1975)
    Weinheim : Wiley-Blackwell
    Materialwissenschaft und Werkstofftechnik 6 (1975), S. 52-54 
    Details
    ISSN: 0933-5137
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Experimental Investigation of the Statistical Size-Effect in Fatigue Tests with Unnotched Specimens.In constant-load-fatigue-tests with unnotched specimens of different lengths, the statistical effect of specimen's size in probability of lifetime to fracture was determined.
    Notes: Im einstufigen Dauerschwingversuch an ungekerbten Proben mit unterschiedlichen Meßlängen konnte der statistische Einfluß der Probengröße auf deren Bruchwahrscheinlichkeit experimentell nachgewiesen werden.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mawe.19750060204
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  • 7
    Electronic Resource
    Electronic Resource
    Produktbereiche bei der Rektifikation homogenazeotroper Mehrstoffgemische (1992)
    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 64 (1992), S. 793-793 
    Details
    ISSN: 0009-286X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cite.330640939
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  • 8
    Electronic Resource
    Electronic Resource
    163. Die diskontinuierliche Rektifikation azeotroper Gemische in der betrieblichen Praxis (1994)
    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 66 (1994), S. 1257-1258 
    Details
    ISSN: 0009-286X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cite.3306609164
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