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  • Chemistry  (10)
  • SPACE RADIATION  (4)
  • Mutants  (1)
  • Computer Systems
  • 1985-1989  (15)
  • 1980-1984
  • 1975-1979
  • 1925-1929
  • 1987  (4)
  • 1985  (11)
Collection
Publisher
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  • 1985-1989  (15)
  • 1980-1984
  • 1975-1979
  • 1925-1929
Year
  • 1
    ISSN: 1432-0983
    Keywords: Yeast ; Mitochondrial ; Mutants ; RNA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary This is a description of a new class of temperature sensitive pet mutants in Saccharomyces cereviase that lose all or part of their mitochondrial RNA at the restrictive temperature. These mutants fall into 8 different complementation groups, mna1 to mna8, and 2 different classes based on their phenotype. Class I mutations, mna1-1 through mna5-1, cause complete or partial loss of mitochondrial RNA at the restrictive temperature. The mutation, mna1-1, is especially interesting since it causes a loss of both mitochondrial DNA and RNA when the mutant is grown on a fermentable carbon source at the restrictive temperature. However, when this mutant is grown at the permissive temperature on a non-fermentable carbon source then shifted to the restrictive temperature, only the mitochondrial RNA is lost. This indicates that the primary cause for the pet phenotype is due to the loss of mitochondrial RNA and not DNA. Class II mutations, mna6-1 through man8-1, cause complete loss of the 14S rRNA after growth at the restrictive temperature in a fermentable carbon source. This loss appears to be specific for the 14S rRNA, since all other transcripts probed by Northern analysis are normal.
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  • 2
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 188 (1987), S. 217-226 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A phenomenological model is proposed which considers the polymer as an aggregate of units. The units are composed of two distinct phases  -  amorphous and crystalline. The thermal conductivity of a unit is calculated in terms of those of its constituents. In the undrawn state these units are distributed randomly, and the isotropic thermal conductivity of the bulk results. The development of strong anisotropy in thermal conductivity is explained in terms of the preferred orientation of these units. The structural features of this model are similar to those employed for the interpretation of the mechanical properties. The change in orientation of the units was deduced from the experimental data of birefringence. Finally, the results obtained from the composite model for several semicrystalline polymers are compared with the experimental data and other existing calculations. The model is found to give a fair overall description of the thermal conductivity in the cases of polypropylene, polyoxymethylene, low and high density polyethylene, and polychlorotrifluoroethylene.
    Additional Material: 4 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 186 (1985), S. 2649-2656 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A unified study of the anomalous mechanical properties and birefringence of low density polyethylene (LDPE) is attempted within the frame work of the rotating element model. The present paper investigates the validity of the affine transformation rule used in the Ward model and suggests a modified affine law which is based on the consideration that the units are only reoriented and, unlike the affine law, are not deformed due to the uniaxial stretching. The relationship between the angles made by the C-axis of the unit with the drawing direction in the undrawn state (θ) and the drawn state (θ), is deduced as sin θ = f(n) sin θ′. From the birefringence data of different polymers a two parameter relation of the form f (n) = exp [-(n - 1)α/β] is suggested. Using this new orientation function, the agreement of the predicted values of E0 and E90 for LDPE for the entire draw ratio range between temperatures of 60°C to -125°C, is quite satisfactory. An interesting feature is that the abrupt change in the values of the parameters α and β at two different temperatures may be associated with a phase transition of LDPE at an intermediate temperature.
    Additional Material: 3 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Letters Edition 25 (1987), S. 187-191 
    ISSN: 0887-6258
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 25 (1987), S. 339-352 
    ISSN: 0887-6266
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Poly[(N-benzyldiphenylamino)methane] was synthesized by the condensation polymerization of benzyldiphenylamine and formalin (30% HCOH in water) and examined for electrical and optoelectronic properties. Dark conductivity and photoconductivity of the polymer film were investigated by steady-state measurements. Current-voltage characteristics and intrinsic photoconduction of the polymer in the visible wavelength range were studied. A superlinear current increase is tentatively explained in the light of the Poole-Frenkel effect. Dielectric constant and dielectric loss parameters of the polymer are independent of frequency (50 Hz-10 kHz) and temperature (273-323 K), respectively. The growth and decay rates of the photocurrent depend on the applied voltage, and the photocurrent varies directly with the light intensity. The activation energies for dark conductivity and photoconductivity are 1.16 eV and 1.05 eV, respectively, and the optical energy band gap as evaluated from absorption coefficient spectra is 2.86 eV.
    Additional Material: 12 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 129 (1985), S. 43-59 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Alle Arten von Ruß enthalten große Anteile an ungepaarten Elektronen und organischen funktionellen Gruppen. Die Polymerisation wird wahrscheinlich durch die ungepaarten Elektronen auf der Oberfläche ausgelöst; die funktionellen Gruppen haben auf die auslösende Reaktion einen Promotor-Effekt. Alle Eigenschaften wie Textur, Geometrie, Größe der Oberfläche, pH der wäßrigen Aufschlämmung, Aschegehalt und elementare Zusammensetzung haben Einfluß auf die Polymerisation. Diese einschlägigen physikochemischen und Oberflächen-Eigenschaften von nicht modifiziertem und modifiziertem Ruß N 220 wurden im Hinblick auf die Polymerisation von N-Vinylcarbazol untersucht.
    Notes: All grades of carbon black contain large amounts of unpaired electrons and organic functional groups. Polymerization reaction is possibly initiated by the unpaired electrons on the surface; the functional groups have promotional effect on the initiation process. All the properties like texture, geometry, surface area, pH of the aqueous slurry, ash content, and elemental composition have effects on the polymerization reaction. These pertinent physicochemical and surface properties of unmodified and modified N 220 carbon black have been studied in relation to N-vinylcarbazole polymerization.
    Additional Material: 5 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 134 (1985), S. 151-164 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Initiatorwirksamkeit von unmodifiziertem und durch Vorbehandlung mit verschiedenen protischen und aprotischen Säuren modifiziertem Ruß N 220 wurde für die Polymerisation von N-Vinylcarbazol untersucht. Die physiko-chemischen Eigenschaften der mit diesen Initiatorsystemen erhaltenen Polymeren wurden durch IR-, Röntgen-, 1H-NMR- und 13C-NMR-Spektroskopie, Gelpermeationschromatographie und thermische Analysen untersucht. Unter bestimmten Bedingungen zeigt das entstehende Polymere eine teilweise Unlöslichkeit in Methylethylketon. Im Gegensatz zur üblichen Meinung ist dieses Verhalten nicht auf stereochemische Unterschiede zwischen den Polymereinheiten zurückzuführen, wie durch 13C-NMR-spektroskopische Analysen der in Methylethylketon unlöslichen Fraktion des Polymeren gezeigt wurde.
    Notes: The polymerization initiating activity of carbon black N220, unmodified as well as modified by pretreatment with various protonic and aprotonic acids has been examined in regards to N-vinylcarbazole polymerization. The physico-chemical characteristics of the polymer obtained by these catalyst systems have been investigated by I.R., X-ray, 1H-NMR, 13C-NMR, gel permeation chromatography and thermal analysis measurements. Under certain conditions the resultant polymer shows some partial insolubility in methylethylketone. Contrary to the usual belief, this is not due to any stereochemical difference between the polymeric entities as observed by 13C-NMR spectrum analysis of the methylethylketone insoluble fraction of the polymer.
    Additional Material: 7 Ill.
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  • 8
    ISSN: 0749-1581
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 13C signal assignments of 3-ethyl-1-methylindole (1), 1-methyl-3-phenylindole (3), 1,3-dimethyl-2-phenylindole (5), 1-methyl-2,3-diphenylindole (10), 1,5-dimethyl-2,3-diphenylindole (12), 7-methoxy-2,3-diphenylindole (13), 7-methoxy-4-methyl-2,3-diphenylindole (14) and 1-(7-methoxy-4-methyl-2,3-diphenyl-6-indolyl)-1-(7-methoxy-2,3-diphenyl-4-indolyl)methane (15) are reported. Contrary to an earlier report on monophenylindoles, the para carbons of the phenyl groups of 3, 5, 10 and 12-15 resonate at lower frequencies than their ortho carbons. The methoxy carbon at position 7 in 15 absorbs at a higher frequency than other similar carbons in 13-15 owing to steric inhibition to resonance.
    Additional Material: 1 Tab.
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  • 9
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 526 (1985), S. 179-185 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Rhenium-Nitrosyl-Komplexe: Thiocyanato-DerivateSchmelzen von K2[Re(NO)Cl5] mit KSCN ergibt [Re(NO)(SCN)5]2-, das als freie Säure bzw. in Form der K+-, Na+-, NMe4+-, Pb2+-, Hg2+-, phenH+- und dipyH+-Salze isoliert werden kann. Eine Verbindung mit der Zusammensetzung Hg2[Re(NO)(SCN)7] wurde ebenfalls dargestellt. [Re(NO)Cl(SCN)4]2- wurde bei der Reaktion von H2[Re(NO)(SCN)5] mit HCl in wäßrigem Medium erhalten und als NMe4+-Salz isoliert. In wäßrigem Medium reagiert Re(NO)Cl3 mit KSCN unter Bildung von [Re(NO)Cl2(SCN)3]2-, das als phenH+- und dipyH+-Salz isoliert wurde. Die Komplexe wurden durch Elementaranalyse, spektroskopisch (UV-VIS, IR), magnetisch und durch Leitfähigkeitsmessungen charakterisiert. Strukturen für die Verbindungen werden vorgeschlagen.
    Notes: Fusion of K2[Re(NO)Cl5] with KSCN produces the ion [Re(NO)(SCN)5]2- which has been isolated as free acid and K+, Na+, NMe4+, Pb2+, Hg2+, phen H+ and dipyH+ salts. A salt of composition Hg2[Re(NO)(SCN)7] has also been prepared. The species [Re(NO)Cl(SCN)4]2- has been obtained from the reaction of H2[Re(NO)(SCN)5] with HCl in aqueous medium and its NMe4+ salt has been isolated. Hydrated Re(NO)Cl3 reacts with KSCN in aqueous medium to produce the ion [Re(NO)Cl2(SCN)3]2- which has been isolated as its phenH+ and dipyH+ salts. The complexes have been characterized through elemental analyses, spectral (u.v., vis., i.r.) properties, magnetic and conductance data. The structures of all those compounds have been proposed.
    Additional Material: 3 Tab.
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  • 10
    Electronic Resource
    Electronic Resource
    Basel : Wiley-Blackwell
    Die Makromolekulare Chemie, Rapid Communications 6 (1985), S. 353-359 
    ISSN: 0173-2803
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 1 Ill.
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