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  • 1
    Electronic Resource
    Electronic Resource
    Effect of polarity of the medium on the stereospecific polymerization of propylene by ansa-zirconocene catalyst (1994)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 32 (1994), S. 2049-2056 
    Details
    ISSN: 0887-624X
    Keywords: metallocenes ; olefin polymerizations ; Ziegler-Natta catalysts ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Propylene was polymerized with rac-ethylene-bis (1-η5-indenyl)dichlorozirconium/methylaluminoxane in solvents of different polarity. The poly (propylene) formed was separated by solvent extraction; 13C-NMR and DSC measurements were made on the polymer fractions. The poly(propylene) in each solvent fraction has its characteristic molecular weight steric pentad distributions, melting transition temperature, and enthalpy for fusion irrespective of the polymerization medium. The results suggest that the medium dielectric constant does not affect the polymerization rate or the intrinsic stereoselectivity, propagation and chain transfer rates a given catalytic species but can alter the occurrence of steric insertion errors through shifting of distributions of the propagating species producing poly(propylenes) of different stereoregularities. © 1994 John Wiley & Sons, Inc.
    Additional Material: 7 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1994.080321106
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  • 2
    Electronic Resource
    Electronic Resource
    Excited states of CF4 plasma for polymerization of TMPTA monomer (1992)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 30 (1992), S. 323-328 
    Details
    ISSN: 0887-624X
    Keywords: CF4 plasma ; trimethylolpropane triacrylate ; excited states ; plasma induced polymerization ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The F and CF2-CF2+ excited states have been detected by emission spectroscopy in CF4RF plasmas used for TMPTA polymerization. These excited states are related through electron collision to F and CF2 ground states. The temporal variation of the F and CF2-CF2+ radiative states near the substrate reveals that the F atoms disappear first by incorporation in the monomer during the polymerization phase and, then, by a third body recombination process enhanced by the polymer surface. The CF2-CF2+ radiative states are varying as the inverse of the F states indicating a strong destruction mechanism of CF2 radicals by F atoms.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1992.080300217
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  • 3
    Electronic Resource
    Electronic Resource
    Polymer drying. VII. 1H-NMR studies of evaporation from liquid saturated poly(styrene-co-divinylbenzene) (1992)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 30 (1992), S. 1155-1161 
    Details
    ISSN: 0887-624X
    Keywords: adsorption ; desorption ; association ; polystyrene ; NMR ; polymer transitions ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Composition-studies were carried out in which samples of films composed of poly(styrene-co-divinylbenzene) particles enmeshed by poly(tetrafluoroethylene) fibers were saturated with dichloromethane and then allowed to evaporate at 23°C to virtual dryness as the 1H-NMR signals and residual weight of sorbed liquid were monitored. The correlations, of 1H-NMR line-widths with the corresponding log of the number, αt of residual sorbed molecules per monomer unit show that sharp changes occur as αt passes through αG the composition that exists when all the liquid not sorbed (i.e., not present within the liquid-saturated particles), has been eliminated, and again as αt passes through αg the composition that exists when the particles attain the rigidity characteristic of the glassy state. Correlation of the corresponding T1 relaxation times with log αt show that sharp changes occur when αt becomes equal first to α′s and then to α′g the compositions that exist respectively when, firstly, all the sorbed liquid not immobilized by adsorption to the polymer chains within the particles has been eliminated, and then when the desorption of immobilized liquid from the chains causes the composition to begin to undergo transition from its rubbery state to its glassy state.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1992.080300622
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  • 4
    Electronic Resource
    Electronic Resource
    Tomographic Techniques for Characterising Particulate Processes (1993)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 10 (1993), S. 252-261 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A review of existing and developing process tomographic instrumentation suitable for characterising dry and wet particulate systems is presented. Factors governing the selection of sensing techniques appropriate for static and dynamic imaging of a wide range of single and multiphase particulate processes are discussed. The paper presents a systematic comparison of different image reconstruction methods. Examples of existing, developing and proven applications are cited. Future needs and ways in which these needs can be met are suggested, including the use of multi-modality methods in which different types of sensing methods are embodied in a single tomographic instrument.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19930100507
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  • 5
    Electronic Resource
    Electronic Resource
    A convenient computer program for calculation of Kováts retention indexes (1992)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 15 (1992), S. 478-479 
    Details
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Kováts retention index ; GW-BASIC program ; Computer-assisted calculation ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240150714
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  • 6
    Electronic Resource
    Electronic Resource
    A novel algorithm for chromatogram matching in qualitative analysis (1992)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 15 (1992), S. 539-547 
    Details
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Neural networks ; Pattern recognition ; Simulated data ; Simulated annealing ; Essential oils ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The matching of the pattern of peaks produced during gas chromatography is of importance to many applications. At present, this task is generally performed manually, but this generates the usual problems associated with human inspection, such as a lack of objectivity and reproducibility, proneness to errors, and practical restriction of the volume of data which can reasonably be processed.This paper explores the use of a novel algorithm for automation of this task. The performance of the method on well controlled simulated data sets and real chromatograms is used to show not only how problems of manual inspection can be circumvented, but also how the existence of such a powerful method should open up the possibility of many new analyses for quality control, discrimination of varieties of sample, and the identification of specific components within a sample.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240150811
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  • 7
    Electronic Resource
    Electronic Resource
    Letter to the editor (1993)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 16 (1993), S. 52-52 
    Details
    ISSN: 0935-6304
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240160110
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  • 8
    Electronic Resource
    Electronic Resource
    Lymphoblastoid cell adhesion mediated by a dimeric and polymeric endogenous β-galactoside-binding lectin (galaptin) (1992)
    Chicester [u.a.] : Wiley-Blackwell
    Journal of Molecular Recognition 5 (1992), S. 1-8 
    Details
    ISSN: 0952-3499
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Glutaraldehyde-polymerized human splenic galaptin, a β-galactoside-binding lectin, was demonstrated to have enhanced hemagglutinating and asialofetuin binding activity relative of native dimeric galaptin when these lectins were present in solution. The polymerized lectin consisted primarily of 2-, 4- and 12-membered species after reductive alkylation. Both forms of galaptin bound, at 4 °C, to saturable B lymphoblastoid cell surface receptors. Estimates obtained by Scatchard analyses, with the binding data expressed in terms of 14.5 kDa subunit molarity, were 5 × 107 binding sites/cell with affinity constant Ka = 2.2 × 105 M for dimeric galaptin and 17 × 107 binding sites/cell with Ka = 3.4 × 105 M-1 for polymeric galaptin. Both forms of galaptin adsorbed to polystyrene with high efficiency; however, only plastic-adsorbed polymeric galaptin mediated adhesion of lymphoblastoid cells. Cell adhesion was inhibited by lactose. Plastic-adsorbed polymeric galaptin bound asialofetuin more efficiently than dimeric galaptin. Asialofetuin binding was inhibited 65% and 30-50% by lactose for plastic-adsorbed polymeric and dimeric galaptin, respectively, Native fetuin bound to the adsorbed dimeric galaptin in a lactose-insensitive manner. These data indicate that cell surface receptor-galaptin interaction is carbohydrate specific whereas polystyrene-adsorbed galaptin may demonstrate protein-protein interactions with soluble ligands.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmr.300050102
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  • 9
    Electronic Resource
    Electronic Resource
    Synthesis and characterisation of polyamides and polyimides from methylene bis[benzenamine] styryl pyridines (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Polymer International 34 (1994), S. 35-39 
    Details
    ISSN: 0959-8103
    Keywords: polyamides ; polyimides ; styryl pyridines ; synthesis ; characterisation ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Two diamines with potential non-linear optical characteristics, (E)-4, 4′-[[[2-(4-pyridinyl)ethenyl]phenyl]methylene]bis[benzenamine] (2a) and (E)-4, 4′-[[[2-(4-pyridinyl)ethenyl]phenyl]methylene]bis [N-ethylbenzenamine] (2b), were condensed with dianhydrides, benzophenone tetracarboxylic dianhydride and pyromellitic dianhydride, to obtain polyamic acids. These polyamic acids were soluble in polar aprotic solvents such as dimethyl formamide and dimethyl acetamide, and could be cast into transparent, tough and flexible films, which on cyclodehydration yield amorphous thermally stable polyimides. Characterisation using IR spectroscopy, X-ray diffraction, thermogravimetric analysis and differential scanning calorimetry are reported.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pi.1994.210340106
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  • 10
    Electronic Resource
    Electronic Resource
    Optimization of short-column gas chromatography/electron ionization mass spectrometry conditions for the determination of underivatized anabolic steroids (1992)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 21 (1992), S. 420-430 
    Details
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A gas chromatographic/mass spectrometric method based on the use of short capillary gas chromatograph columns (3-5 m) and electron ionization mass spectrometry has been optimized and evaluated for the determination of underivatized anabolic steroids. The short-column gas chromatographic/mass spectrometric method was shown to result in short analysis times and to require minimal sample preparation, but suffered from some loss in sensitivity and chromatographic resolution compared with conventional gas chromatographic/mass spectrometric techniques for derivatized steroids. Therefore, short-column gas chromatographic conditions were optimized to maximize the sample transfer efficiency (sensitivity) from the gas chromatograph into the ion source of the mass spectrometer, while maintaining chromatographic integrity and minimizing thermal decomposition. Mass spectrometric conditions were optimized to maximize ionization efficiency with respect to the intensity of the molcular ion and degree of fragmentation such that positive identication of each steroid could be made based on the resulting mass spectra. Under optimized conditons, we have shown that underivatized anabolic steroids spiked into urine samples can be determined at low-nanogram levels using short-column chromatography/full-scan electron ionization mass spectrometry.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200210903
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