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  • 1
    Electronic Resource
    Electronic Resource
    Ion complexation in nonactin, monactin, and dinactin: A Raman spectroscopic study (1977)
    New York : Wiley-Blackwell
    Biopolymers 16 (1977), S. 157-185 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The ability of the macrotetrolide nactins to complex selectivity with a wide variety of cations makes these ionophorous antibiotics important model systems for the study of biologic ionic transport. We report a Raman spectroscopic investigation of the Na+, K+, Rb+, Cs+, Tl+, NH4+, NH3OH+, C(NH2)3+, and Ba++ complexes of nonactin, monactin, and dinactin in 4:1 (v/v) CH3OH/CHCl3 and in the solid state. The nactins display characteristic spectral changes upon complexation, some of which are specific for a given cation. In the K+, Rb+, Cs+, NH3OH+, and C(NH2)3+ complexes, which are apparently isosteric, the ester carbonyl stretch frequency is found to be linearly proportional to the cation-carbonyl electrostatic interaction energy, as calculated from a simplified model. Deviations for the Na+, NH4+, Tl+, and Ba++ complexes are interpreted as arising from additional nonelectrostatic interactions. Additional information is obtained from other spectral regions and from measurements of depolarization ratios. Spectra of the nactin complexes differ from each other more in the solid state than in solution, reflecting the effects of crystalline contact forces.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1977.360160112
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  • 2
    Electronic Resource
    Electronic Resource
    Nematic polymers: Excluded-volume effects (1979)
    New York : Wiley-Blackwell
    Biopolymers 18 (1979), S. 2315-2322 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We present a theoretical model which describes a cooperative helix-coil liquid-crystal phase transition. We show that this model predicts a first-order phase transition where certain types of chainlike macromolecules in solution make a transition from a nearly coiled to a nearly rigid conformation accompanied by a simultaneous development of long-range nematic-type liquid crystalline orientational order. From this model, the phase boundaries between nematic and isotropic phases are obtained as functions of concentration of macromolecules and of other physical parameters.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1979.360180918
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  • 3
    Electronic Resource
    Electronic Resource
    [D-Ala2, Phe (p-NO2)4, Leu5]Enkephalin Amide and Nα-[D-Ala2, Leu5]-Enkephalyl-Nε-Acetyl-Lysine Amide: Synthesis and Biological Properties of Prospective Enkephalin Cooperative-Affinity and Photoaffinity Labels. Preliminary communicationThis work was supported by operating grants from the Medical Research Council of Canada (MA-5655), the Quebec Heart Foundation and the Swiss National Science Foundation. It is part of the doctoral theses of K.Q.D. and P.T. The permanent address of Prof. J.V.C. is Facultad de Medicina de la Universidad Autonoma, Madrid 32, Spain. Abbreviations are according to the IUPAC-IUB Commission on Biochemical Nomenclature (compiled and reprinted by the American Society of Biological Chemists, Inc., Bethesda, Md. 20014, U.S.A., second edition 1975). An amino acid symbol beginning with a capital letter denotes the L-configuration (except Gly), one beginning with a lower-case letter stands for the D-enantiomer (e.g. ala≡D-Ala). (1979)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 62 (1979), S. 525-529 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: As a study preliminary to attempts at photoaffinity and cooperative affinity labelling of cells and cell membrane vesicles bearing opiate receptors, the title compounds were prepared and tested by rat brain membrane binding assays and by a modified guinea-pig ileum bio-assay. The potency of the two compounds in both systems was considerably greater than that of the standard peptide, [Leu5]enkephalin, justifying further work with these and similar compounds.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19790620219
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  • 4
    Electronic Resource
    Electronic Resource
    The Synthesis of (S)-(+)-2-Amino-3-(1-adamantyl)-propionic Acid (L-(+)-Adamantylalanine, Ada) as a ‘Fat’ or ‘Super’ Analogue of Leucine and PhenylalanineAbbreviations are according to the IUPAC-IUB Commission on Biochemical Nomenclature (compiled and reprinted by the American Society of Biological Chemists, Inc., Bethesda, Md. 20014, U.S.A., second edition 1975). In addition, Ada stands for L-(+)-adamantylalanine, ada for its D-enantiomer, and BOC- for t-butoxycarbonyl. (1979)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 62 (1979), S. 956-964 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Because of its overall steric resemblance to the phenylalanine analogue, carboranylalanine, the title compound was prepared by the modified Strecker synthesis of Patel & Worsley. The use of (S)-(-)-α-methylbenzylamine in the synthesis, the positive trend of [α]D with increasing protonation, and the thin-layer chromatographic behaviour of synthetic diastereomeric dipeptides are strong indications that the configuration at the asymmetric carbon atom is S (natural L). Its optical purity was ascertained by purification via the quinine and ephedrine salts of t-butoxy-carbonyl-adamantylalanine. The new amino acid shall be used for studies of structure-activity relationships of phenylalanine and leucine residues in biologically active peptides. In addition, a convenient synthesis in excellent yield of the starting material, 2-(1-adamantyl)-ethanal, by Pfitzner-Moffat oxidation of 2-(1-adamantyl)-ethanol is described.
    Additional Material: 7 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19790620405
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  • 5
    Electronic Resource
    Electronic Resource
    Crystallization of poly(L-proline) in the course of polymerization (1979)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 180 (1979), S. 465-472 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The heterogeneous polymerization of L-proline N-carboxy anhydride was carried out in acetonitrile and benzene, using butylamine as the initiator. Polyproline I was formed in acetonitrile and polyproline II in benzene in the course of the polymerization. The conversion attained 99% and 66% after 1 week-polymerization in acetonitrile and benzene, resp. Extended chain crystals were obtained by the polymerization in acetonitrile. On the other hand, poly(L-proline) obtained by the polymerization in benzene gave aggregates into which many growing chain ends were occluded. The differences in the crystallization behaviour during the polymerization between the two different liquids may be due to the conformation of the resultant polymers. Polyproline I exhibits a cross-section per chain of 0.709 nm2, whereas polyproline II shows only one of 0,386 nm2. The wider the cross-section per chain the more the growing, active chain ends can react with the monomer, giving rise to a higher conversion. In contrast with the case of crystallization of such α-helical chains as poly(L-alanine) during polymerization, hexagonal lamellar crystals were formed.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1979.021800219
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  • 6
    Electronic Resource
    Electronic Resource
    Growth mechanism of crystals of glycine/S-methyl-L-cysteine copolymer in the course of polymerization (1977)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 178 (1977), S. 2089-2095 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: In order to examine the growth mechanism of copolymer crystals formed during polymerization, the heterogeneous copolymerization of glycine N-carboxy anhydride (2,5-dioxo-1-oxa-3-azacyclopentane) and S-methyl-L-cysteine N-carboxy anhydride (4-methylthiomethyl-2,5-dioxo-1-oxa-3-azacyclopentane) was studied in acetonitrile. In all the polymerization systems, the crystal growth occurs through formation of the cross-β-type structure. The high conversion in the glycine-rich systems is accounted for by the widening of the cross-section of the β-chain in the backbone crystal, due to the introduction of S-methyl-L-cysteine residues into the polyglycine chain. On the other hand, the narrowing of the cross-sectional area per chain in the skeleton crystals of the oligomer gave rise to the lowering of the conversion in the S-methyl-L-cysteine-rich systems. This shows the importance of the effect of the cross-sectional area of the oligomer chain (of the β structure) in the crystal formed in the begining relative to that of the growing (α-helical) chain. The glycine residue seems to be incorporated into the crystalline lattice of the S-methyl-L-cysteine and vice versa.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1977.021780723
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  • 7
    Electronic Resource
    Electronic Resource
    A finite element formulation for creep analysis (1977)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 11 (1977), S. 1865-1877 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: As an alternative to the initial strain method, a variable stiffness method is presented for creep analysis. The method is developed by incorporating the change in stress state during a time interval in determining the creep strain increments concurrent with the change. It is shown by means of examples that this method provides solution stability for relatively large time intervals for which the initial strain method may fail to function properly.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620111209
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  • 8
    Electronic Resource
    Electronic Resource
    Studies on melt spinning. VII. Elongational viscosity and fiber morphology of multiphase polymer systems (1977)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 21 (1977), S. 515-524 
    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
    Notes: Melt spinning experiments were carried out to investigate the elongational behavior and fiber morphology of multiphase polymer systems. Materials chosen for study were blends of calcium carbonate-filled polypropylene with general-purpose polystyrene and blends of calcium carbonate-filled polypropylene with high-impact polystyrene. The former is a three-phase system in which the CaCO3 particles are dispersed, and the latter is a four-phase system in which CaCO3 particles are dispersed, together with rubbery butadiene particles. Note that polypropylene is incompatible with the matrix of high-impact polystyrene. The experimental technique described in part I of this series was used to determine the elongational viscosity. With the four-phase system, the apparent elongational viscosity tends to increase as the stretch ratio is increased above a certain critical value which appears to be ca. 25. This transition does not occur with the three-phase system and is attributable to elongation of the suspended rubber particles. The addition of small amounts of HIPS to PP-CaCO3 increases spinnability in general, whereas larger amounts decrease spinnability.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1977.070210217
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  • 9
    Electronic Resource
    Electronic Resource
    Morphology and mechanical properties of injection-molded specimens of two-phase polymer blends (1977)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 21 (1977), S. 353-370 
    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
    Notes: An experimental study was carried out to investigate the moldability of polymer blends which form two phases in the molten state and the effect of mixing on the morphology and mechanical porperties of molded specimens. Blends of polystyrene with polypropylene and blends of polystyrene with high-density polyethylene were used for this study. A plunger-type injection molding machine (Van Dorn) was employed for molding specimens. To improve the mixing performance of the plunger machine, a Static Mixer (Kenics Corp., Super Nozzle) was installed between the heating cylinder and the sprue. A number of different molding conditions (injection pressure, temperature, injection time, cooling time) were varied, and molded specimens were collected under each molding condition. The specimens were used for studying the degree of dispersion in the blends and for determining the mechanical properties. A differential thermal analysis (DTA) experiment was also carried out to determine the degree of dispersion of the blends in molded specimens. It was found that a linear correlation exists between the blend composition and thermal spectra area of the blends tested.
    Additional Material: 18 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1977.070210205
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  • 10
    Electronic Resource
    Electronic Resource
    Effects of external diffusion and design geometry on the performance of immobilized glucose isomerase reactor system (1979)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 21 (1979), S. 2023-2043 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Using immobilized glucose isomerase, the effects of superficial velocity of the reaction solution flowing through a packed-bed reactor on the apparent kinetic constants of reversible reaction system were studied. The results showed that the apparent kinetic constants, both Vm″ and Km″, of the forward reaction varied significantly as the superficial velocity is changed, whereas those of the reverse reaction varied only slightly. Using the kinetic data determined experimentally, computer simulation of the enzyme reactor performance was carried out, and the importance of the external mass transfer in the proximity of immobilized-enzyme particles was recognized. The reactor performance, expressed in terms of productivity, was examined as a function of the reactor height-to-diameter ratio, H/D. The productivity of the reactor system goes through a maximum value at a H/D ratio of about 1.6. and decreases as the H/D ratio increases. Theoretical analysis of the reaction kinetics of immobilized-enzyme system that has reversible reaction kinetics is also presented. The experimental results showed good agreement with the results found from the theoretical analysis and the computer simulation studies. Based on the principles of the methods and the results presented in this paper, it is anticipated that one can predict the optimal design and operating conditions for the glucose isomerase reactor system and that application of the results could be extended to other enzyme systems with reversible reaction kinetics.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260211110
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