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  • Articles  (42)
  • Polymer and Materials Science  (25)
  • Life and Medical Sciences  (17)
  • 2015-2019
  • 1985-1989  (42)
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  • Articles  (42)
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  • 1
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 28 (1989), S. 1235-1246 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cyclic octapeptides having alternating Sar and hydrophobic amino acid sequences, such as cyclo[Lys(Z)-Sar-Leu-Sar-Leu-Sar-Leu-Sar] (C8KL), cyclo[Glu(OMe)-Sar-Lys(Z)-Sar-Leu-Sar-Leu-Sar] (C8KE), and cyclo[Lys(Suc)-Sar-Leu-Sar-Leu-Sar-Leu-Sar][C8K(Suc)L, Suc represents succinic acid], were synthesized. These cyclic octapeptides formed a complex selectively with Ca2+. Upon complexation, trans peptide bonds of Sar residues were isomerized to cis peptide bonds. C8KL and C8KE showed very similar characteristics of Ca2+ binding, extraction of Ca2- from an aqueous solution to a chloroform solution, and Ca2+ transport through a liquid chloroform membrane. C8KL transported Ca2+ across the lipid bilayer membrane above the phase-transition temperature, while C8KE and C8K(Suc)L did not. Therefore, the transport of Ca2+ through the lipid bilayer membrane is very sensitive to the hydrophobicity of the carrier molecule.
    Additional Material: 10 Ill.
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  • 2
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: 3-Methyl-2-isopropenyl-2-oxazolinium salts (4a, b) were prepared by alkylation of 2-isopropenyl-2-oxazoline (2). Their preparation is much easier than that of their vinyl analogues, 3-methyl-2-vinyl-2-oxazolinium salts, which cannot be isolated due to their high tendency to polymerization. 4a, however, was found, to show a low tendency toward radical and anionic polymerization, but it can be smoothly radically copolymerized with some vinyl monomers. The copolymerization parameters of 4a were determined and discussed in comparison with those of 2.
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  • 3
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 186 (1985), S. 61-70 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The proton-decoupled signal of methyl carbons of O-(2-hydroxypropyl)cellulose (HPC) (1b, m ≥ 1) was found to be split into two peaks. The results of experiments on lanthanide shift and the dependence of the relative intensities of both peaks on the molecular weight of poly(oxypropylene) [poly(propylene oxide)] (PPO) indicated that the low-field peak results from the terminal hydroxypropyl groups and the high-field peak from the inside oxypropylene units. From the ratio between the intensities of the two peaks and the molar substitution (MS) (average number of oxypropylene units per anhydroglucose (AHG) unit), the degree of substitution (DS) (average number of hydroxyl groups substituted per AHG unit) was calculated. This new method could be applied to samples of low-MS to which the conventional method based on the 1H NMR technique alone was inapplicable. From the analysis of 13C NMR spectra of HPC samples differing in MS, an authentic structural picuture of the HPC molecule could be proposed.
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  • 4
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 190 (1989), S. 2693-2701 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Chemically and thermally stable thin films of polyphthalocyanine were prepared by a simple evaporation-polymerization method. The rectifying characteristics of metal/semiconductor/metal (MSM) type sandwich devices with the film were studied. A Schottky type device metal (Cu, Al, Ti)/polyphthalocyanine/Cu shows reproducible rectifying characteristics when Ti is selected as a counter electrode. The reproducibility is improved by pre-oxidation treatment of the surface of Cu substrate. Best electric parameters for the device are as follows: rectifying ratio = 14; threshold potential difference = 0,61 V; saturation current = 2,5 · 10-6 A · cm-2; barrier height = 0,75 eV; diode ideality parameter = 4,23. Doping of five kinds of quinones [p-benzoquinone (p-BQ), tetrabromo-p-benzoquinone (p-TBBQ) tetrachloro-p-benzoquinone (p-TCBQ) tetrachloro-o-benzoquinone (o-TCBQ) 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ)] and 2,5-cyclohexadien-1,4-diylidenedimalodinitrile (TNCR) in thin films of polyphthalocyanine affected electrocharacteristics in some cases. The diode ideality parameter decreases to 2,17 at 0,90 · 10-6 mol · cm-1 of p-TBBQ, and the rectifying ratio increases to about fourteen times by doping p-TBBQ and p-TCBQ. The doped device shows a rectifying response up to 1 kHz.
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  • 5
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: An equilibrium blue colored solution containing poly(vinyl alcohol) (PVA)-iodine-boric acid was prepared at 5°C. With increasing PVA concentration, at the same concentration of iodine, the absorption band of the chromophore I5- (λmax = 650 nm, band D) linearly increased and the intensities of the bands for both I- (λmax = 226 nm, band A) and I3- (λmax = 290 nm, band B) decreased. The band due to another iodide species (λmax = 355 nm, band C), tentatively assigned to I3- · I2, remained unchanged. Three solutions with different PVA concentration were then extracted with the same volume of carbon tetrachloride to remove I2 present in the system. It was found that the chomophore due to I5- gradually decays with repeated extractions. After one extraction the change of the absorbance of I5- with time was measured at 5°C. In the system with a high PVA concentration the chromophore recovers the equilibrium within three days without losing much intensity, while in the systems with lower PVA concentration recovering of equilibrium takes more than four days with a considerable loss of chromophore. In the latter case, free I2 extracted is supplied by the decomposition of polyiodide ions to I-. Analysis of the rate of re-equilibration of iodine species revealed two reaction processes: one is a reaction involving free iodine species in an aqueous environment and the other is a slow reaction involving the polyiodide ions bound in a PVA cage.
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  • 6
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 190 (1989), S. 939-950 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Aqueous poly(vinyl alcohol) (PVA)-iodine-boric acid solution was treated with anion exchange resin and the system involving only the cage complex was isolated. The system was then extracted with carbon tetrachloride, and I2 and I-, which were released from the complex, were separated and pooled in the carbon tetrachloride and the aqueous layers, respectively. From the absorption spectra of the layers the amounts of I2 and I- were determined. The ratio I2/I- was found to be approximately 2,0, which corresponds to the I2/I- stoichiometry in the complex. This result suggested that the major species bound in the PVA cage are pentaiodide ions, i.e., I5- with linear configuration and/or I2· I3- with distorted chain structure. Judging from the resonance Raman spectrum of the PVA-iodine solution that had been revealed before, it was concluded that the two absorption bands of the complex at λmax = 650 and 355 nm are ascribed to the I5- and I2 · I3- ions, respectively.
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 33 (1987), S. 3019-3036 
    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: The macroscopic order parameter S in the cholesteric liquid crystalline phase of hydroxypropyl cellulose (HPC) and ethyl cellulose (EC) solutions was calculated using refractive index data. Haller's extrapolation approach was used. The S calculated was compared with the S predicted from Doi's theory. The calculated values of S for HPC and EC solutions were in the range of 0.4-0.8 within our experimental range, and agreed with the predicted values of S obtained with Doi's theory. This result suggests that Haller's approach is valid for determining S for liquid crystalline solutions of HPC and EC, despite the scattering of the data at higher temperatures.
    Additional Material: 24 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 24 (1986), S. 1161-1171 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The relationship between chemical structure and low-temperature modulus of ultraviolet(UV)-radiation-cured optical-fiber coating materials has been investigated. The coating materials are low-viscosity liquid compounds consisting of a 1,4-polybutadiene diacrylate oli-gomer, a monomer, and a photoinitiator. Dynamic mechanical test results show that low-temperature modulus and glass transition temperature (Tg) are affected by the monomer structure and monomer concentration in the coating material in cases where the same oligomer is used. With increasing alkyl group chain length of the alkylacrylate monomer, the Tg value is shifted to lower temperatures. Low-temperature modulus increases with increasing monomer concentration in the coating material. Low-temperature excess optical losses of coated fibers have been found to be closely related to low-temperature modulus of the coating.
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  • 9
    Electronic Resource
    Electronic Resource
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 36 (1988), S. 311-322 
    ISSN: 0730-2312
    Keywords: B16 melanoma ; metastatic variants ; met 72/83 antigen ; immunohistochemistry ; localization in situ ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Metastatic variants of the B16 melanoma displaying high experimental metastatic potential have been shown to express high levels of a 72,000-dalton glycoprotein (Met-72) on their cell surface (Kimura AK, Xiang J: J Nat Can Inst 76:1247-1253, 1986). Monoclonal antibodies (MoAb) directed against the Met-72 determinant have been used in this study as immunohistochemical reagents on preparations of fresh B16 melanoma tumors and their metastases. These immunohistochemical analyses have utilized frozen sections, impression smears, and cytospin preparations of fresh tumors harvested at various time points during tumor growth, to view the presence and location of Met-72-positive metastatic variants within tumor masses. Biotinylated anti-Met-72 MoAbs were reacted with freshly dissociated tumor cells from a B16 melanoma ovarian metastasis. These cells were then reacted with fluorescein isothiocyanate (FITC)-streptavidin and analyzed by flow cytometry. A discrete population of positively staining cells was detected and isolated by cell sorting techniques. Met-72-positivc cells were then cloned and reanalyzed after several weeks of in vitro expansion and found to have high experimental metastatic potential to ovaries. Frozen sections of subcutaneous tumors and their metastases were analyzed by immunoperoxidase techniques. A consistent finding in these studies has been that the few tumor cells which showed high intensity of Met-72 staining were positioned perivascularly and at the invading front of B16 melanoma tumors.
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  • 10
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 28 (1989), S. 1247-1257 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Effects of the nature and orientation of a side chain in cyclic octapeptides on Ca2+ transport were examined by using cyclo[L-Lys(Z)-Sar-LLeu-Sar]2 (C8-L), cyclo[L-Lys(Z)-Sar]4 (C8KS), and their diastereomer cyclic octapeptides, cyclo[L-Lys(Z)-Sar-D-Leu-Sar]2 (C8-D) and cyclo[L-Lys(Z)-Sar-D-Lys(Z)-Sar]2 (C8Kk). All these cyclic octapeptides were found to take a single conformation in CDCl3, and the conformation was C2-symmetric for C8-L and C8-D, and C4-symmetric for C8KS and C8Kk. They formed a complex with Ca2+. Upon complexation, C8KS accompanied isomerization of peptide bonds, but C8-D retained the arrangement of peptide bonds. The amount of Ca2+ extracted from an aqueous solution to a chloroform solution by all L cyclic octapeptide C8-L or C8KS was about twice that of Na+, but 6 ∼ 8-fold smaller than that by C8-D or C8Kk including D units. These cyclic octapeptides were capable of transporting Ca2+ through a lipid membrane above the phase transition temperature, and the transport rate decreased in the order of C8Kk ∼ C8KS 〉 C8-D 〉 C8-L.
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