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  • 1
    Electronic Resource
    Electronic Resource
    The Enantioselective Synthesis of β-Amino Acids, their α-hydroxy derivatives, and the N-terminal components of bestatin and microginin (1996)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 79 (1996), S. 1203-1216 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: L-Aspartic acid by tosylation, anhydride formation, and reduction with NaBH4 was converted into (3S)-3-(tosylamino)butan-4-olide (8; Scheme 1). Tretment of 8 with ethanolic trimethylsilyl iodide gave the N-protected deoxy-iodo-β-homoserine ethyl ester 9. The latter, on successive nucleophilic displacement with lithium dialkyl-cuprates ( → 10a-e), alkaline hydrolysis ( → 11a-e), and reductive removal of the tosyl group, produced the corresponding 4-substituted (3R)-3-aminobutanoic acids 12a-e (ee 〉 99%). Electrophilic hydroxylation of 8 ( → 19; Scheme 3), subsequent iodo-esterification ( → 21; Scheme 4), and nucleophilic alkylation and phenylation afforded, after saponification and deprotection, a series of 4-substituted (2S, 3R)-3-amino-2-hydroxybutanoic acids 24 including the N-terminal acids 24e ( =3) and 24f ( =4) of bestatin and microginin (de 〉 95%), respectively.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19960790426
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  • 2
    Electronic Resource
    Electronic Resource
    Factors affecting the role of SiO2 in MgCl2-supported Ziegler-Natta copolymerization catalysts (1993)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 194 (1993), S. 211-221 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: This paper describes the roles of silica (SiO2), the butoxy ligand (—OBu) and ethyl benzoate (EB) on ethylene/1-butene copolymerization with MgCl2/SiO2-supported titanium catalysts. The distribution of SiO2 and of the elements Mg and Ti was observed by means of an energy-dispersed X-ray micronalyzer on a scanning electron microscope (SEM). An inversed Si/Mg ratio results, at invariant Ti/Mg ratio and—OBu content, in higher catalyst efficiency and higher comonomer incorporation, with a correspondingly decreased crystallinity of the copolymers. Thus, the inert carrier SiO2 favors copolymerizability, as seen from the values of the reactivity ratios. The copolymer compositional distribution is also affected by the SiO2 content, as seen from the DSC curves of the copolymers. As to the copolymer morphology, addition of SiO2 makes the copolymer particles larger and more uniform.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1993.021940117
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  • 3
    Electronic Resource
    Electronic Resource
    Unsteady diffusion kinetics of Ziegler-Natta heterogeneous catalyst polymerization, 4Part 3: cf. ref.3.. Prediction of experimental results of propylene/ethylene/1-hexadecene terpolymerization (1993)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 194 (1993), S. 1807-1816 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The prediction, based on unsteady diffusion kinetics, of the enhancement of reactivity and incorporation of 1-hexadecene in its copolymerization with propylene on adding a small amount of ethylene (increase from 5,2 mol-% to 10,8 mol-% when 2% of ethylene was added, and to 16, 1 mol-% when 5% was added) was verified in the terpolymerization of propylene/ 1-hexadecene/ ethylene on a commercial Solvay-type δ-TiCl3 catalyst. The catalyst efficiency was thus also increased. These augmentations originate from the increase in diffusion coefficient of 1-hexadecene at the catalyst surface when the PP crystallinity decreases on introduction of ethylene. Calculation based on unsteady diffusion kinetics showed that the order of diffusion coefficients ethylene 〉 propylene 〉 1-hexadecene is reversed as the monomer concentration increases when the monomers are not at their equilibrium concentration. Sequence distribution as determined by means of 13C NMR revealed a tendency of blocky structure rather than a Bernoullian one. The terpolymer compositions obtained by means of an IR method developed in this work conform rather well with the NMR results. Results in this work not only support the unsteady diffusion kinetics but also provide a new route to prepare olefinic copolymer rubbers with heterogeneous titanium catalysts.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1993.021940627
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  • 4
    Electronic Resource
    Electronic Resource
    Removal of lead from aqueous solutions by Penicillium biomass (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 42 (1993), S. 785-787 
    Details
    ISSN: 0006-3592
    Keywords: biosorption ; biosorbent ; Penicillium ; biomass ; lead ; wastewater treatment ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The removal of lead ions from aqueous solutions by adsorption on nonliving Penicillium chrysogenum biomass was studied. Biosorption of the Pb+2 ion was strongly affected by pH. Within a pH range of 4 to 5, the saturated sorption uptake of Pb+2 was 116 mg/g dry biomass, higher than that of activated charcoal and some other microorganisms. At pH 4.5, P. chrysogenum biomass exhibited selectivity for Pb+2 over other metal ions such as Cd+2, Cu+2, Zn+2, and As+3 Sorption preference for metals decreased in the following order: Pb 〉 Cd 〉 Cu 〉 Zn 〉 As. The sorption uptake of Pb+2 remained unchanged in the presence of Cu+2 and As+3, it decreased in the presence of Zn+2, and increased in the presence of Cd+2. © 1993 John Wiley & Sons, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260420615
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  • 5
    Electronic Resource
    Electronic Resource
    Thermal regeneration of the phenol-carbon system (1985)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 31 (1985), S. 496-498 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690310321
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  • 6
    Electronic Resource
    Electronic Resource
    Solution behavior of random copolymers of styrene with sodium-2-acrylamido-2-methylpropane sulfonate (1991)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 29 (1991), S. 1361-1371 
    Details
    ISSN: 0887-6266
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The nonaqueous solution behavior of random copolymers of styrene (ST) with sodium-2-acrylamido-2-methylpropane sulfonate (Na-AMPS) [poly(ST-Na-AMPS)] has been investigated using the transient electric birefringence (TEB) technique. The copolymers with varying high sulfonate contents (about 30-70 mol%), bridging the gap between conventional ionomers and classical polyelectrolytes, were dissolved in the solvent methylformamide (MFA) with a high permittivity ∊ of ca. 190. The solutions showed a negative birefringence at electric field strength E of the order of kV/cm. A typical Kerr effect was observed at low polymer concentrations C of ca. 10-3g/mL and electric field strengths of the order of kV/cm. However, the detailed, TEB studies demonstrated different behavior at two concentration regimes in dilute solution. At a low concentration regime (e.g., C ≤ 1 × 10-3g/mL for the copolymer with a 66.7 mol % sulfonate content) where the reduced viscosity exhibited a pronounced polyelectrolyte effect, the birefringence signal pattern showed a maximum before reaching a steady value. Additionally, during the rise at an applied electric field strength beyond a threshold value, it was observed that the nonexponential field-free decay was slower than the single exponential field-induced rise. The observed anomalous behavior was similar to those of a polyelectrolyte [sodium poly (styrene sulfonate)] in aqueous solution and might be attributed to the perturbation of the molecular shape by the applied electric field. At the higher concentration regime (e.g., C ≥ 4 × 10-3g/mL for the same copolymer with a 66.7 mol % sulfonate content) where the polyelectrolyte effects started to diminish as indicated by the viscosity study, the birefringence shape showed no variation with an increased electric field strength and the field-free decay turned out to be faster than the single exponential rise. The dissociation of ionic aggregates was tentatively interpreted to be responsible for this observation. It seems that by simply varying the polymer concentration, poly (ST-Na-AMPS) could behave either as a polyelectrolyte or as an ionomer in a single polar organic solvent.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1991.090291105
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  • 7
    Electronic Resource
    Electronic Resource
    Use of 1-methyl-2-pyrrolidinone in isobutylene polymerization initiated with 1,4-dicumyl alcohol/BCl3 system, leading to living α,ω-di(tert-chloro)polyisobutylenes (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 46 (1992), S. 1117-1119 
    Details
    ISSN: 0021-8995
    Keywords: 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
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1992.070460622
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  • 8
    Electronic Resource
    Electronic Resource
    Chain linear dimensions in the surface-enriched layer of polymer mixtures (1992)
    Basel : Wiley-Blackwell
    Die Makromolekulare Chemie, Theory and Simulations 1 (1992), S. 49-53 
    Details
    ISSN: 1018-5054
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: We calculate the mean-square end-to-end distances and mean-square gyration radii using the bond fluctuation model for a binary polymer blend in the presence of a wall by Monte Carlo simulation. In the bulk, the size of the minority, low-concentration polymer species is compressed compared to the majority one. In the vicinity of the wall, where the minority polymer concentration is enriched due to attraction from the wall, the dimensions of the two types of polymers are approximately equal and are essentially the same as in an athermal polymer melt. Thus, the geometric constraint is more important to the structure of the polymers than the polymer-polymer and polymer-wall interactions.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mats.1992.040010201
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  • 9
    Electronic Resource
    Electronic Resource
    Does vacuum mixing of bone cement affect heat generation? Analysis of four cement brands (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 6 (1995), S. 105-108 
    Details
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Four different brands of bone cement (Palacos R, Simplex P, Sulfix, CMW 1) were tested for exothermic changes during polymerization at atmospheric pressure and under partial vacuum of 0.2 bar. Palacos R was also mixed at four pressure levels (1.0, 0.2, 0.12, and 0.05 bar). The peak temperature in the bone cement was 46 to 124 °C, depending on the measuring point. There was no difference in peak temperature or duration of temperature increase above 50 °C during the curing of cement whether mixed at atmospheric pressure or under partial vacuum at different pressure levels. © 1995 John Wiley & Sons, Inc.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jab.770060204
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  • 10
    Electronic Resource
    Electronic Resource
    Photoswitch based on bacteriorhodopsin Langmuir-Blodgett films (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 4 (1994), S. 219-224 
    Details
    ISSN: 1057-9257
    Keywords: Bacteriorhodopsin ; Langmuir-Blodgett films ; Differential response ; Photoswitch ; Photoalarm ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Langmuir-Blodgett (LB) films of bacteriorhodopsin (bR) without addition of lipids were deposited on indium tin oxide (ITO) conductive electrodes. A sandwich photocell with a juction structure of ITO/bR/electrolyte/ITO has been constructed in which the bR LB film was put into contact directly with an aqueous electrolyte immobilized in an agar gel. Under visible light irradiation a transient photocurrent due to a change in light intensity can be observedl showing the property of vision-imitative material. It can be used as a multiple optical switch, since it gives positive and negative transient photocurrnts during application and removal of light irradiation respectively and has a photoresponse repeatedly in the same direction when the light intensity increases or decreases stepwise. A photoalarm consisting of the bR photocell and an amplifier was set up by utilizing the switching function of the bR LB film.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/amo.860040305
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