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  • Polymer and Materials Science  (11)
  • General Chemistry  (4)
  • Physics  (1)
  • Wiley-Blackwell  (15)
  • 1
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: It is shown that the ULLMANN-reaction for aromatic nitro-iodo compounds practically occurs quantitatively if iodine is located in the o-position to the nitro group.With a corresponding bifunctional compound, 4,4′-diiodo-3,3′-dinitrobiphenyl, the same reaction conditions yielded a nitrosubstituted p-polyphenylene, a bright yellow insoluble and infusible powder which decomposes at higher temperature (〉 250°C.). Based on the iodine content (end groups) an average degree of condensation of 52 was calculated; this corresponds to a p-phenylene chain of 104 benzene rings. The polymer is crystalline and has a long period of ca. 30 Å.The investigations of nitro substituted p-oligophenylenes were conducted primarily for the influence of nitro substitution on solubility. However, on the whole, nitro substitution rather decreases solubility, although in polar solvents e.g., nitro benzene or dimethyl-formamide considerable solubility increases could be observed. From these it appears reasonable that the nitro substituted p-polyphenylene described above is insoluble.For the synthesis of nitro substituted p-oligophenylenes the ULLMANN reaction proved to be very efficient. The iodine compounds needed as starting material were partially obtained by direct iodination with iodine liodic acid.
    Notes: Bei aromatischen Nitrojodverbindungen nimmt die ULLMANN-Reaktion unter verhältnismäßig milden Bedingungen einen praktisch quantitativen Verlauf, wenn sich das Jod in der o-Stellung zu einer Nitrogruppe befindet.Mit einer entsprechenden bifunktionellen Verbindung, dem 4,4′-Dijod-3,3′-dinitrobiphenyl, konnte unter den gleichen Bedingungen ein nitrosubstituiertes p-Polyphenylen erhalten werden, ein hellgelbes, unlösliches und unschmelzbares Pulver, das sich bei höherer Temperatur (〉 250°C) zersetzt. Auf Grund des Jodgehaltes (Endgruppen) wurde ein mittlerer Kondensationsgrad von 52 berechnet; das entspricht einer p-Phenylenkette aus 104 Benzolringen. Das Polymere ist kristallin und besitzt eine Langperiode von ca. 30 Å.Die Untersuchungen an nitrosubstituierten p-Oligophenylenen galten vor allem dem Einfluß der Nitrosubstitution auf die Löslichkeit. Im ganzen gesehen wirkt die Nitrosubstitution eher löslichkeitssenkend als -fördernd, wenn auch in polaren Lösungsmitteln wie Nitrobenzol oder Dimethylformamid beachtenswerte relative Löslichkeitssteigerungen zu beobachten sind. Die dabei gewonnenen Erkenntnisse lassen es verständlich erscheinen, daß das beschriebene nitrosubstituierte p-Polyphenylen unlöslich ist.Für die Synthese der nitrosubstituierten p-Oligophenylene bewährte sich vor allem die ULLMANN-Reaktion. Die als Ausgangsprodukte benötigten Jodverbindungen konnten z. T. durch direkte Jodierung mit Jod/Jodsäure erhalten werden.
    Additional Material: 1 Ill.
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  • 2
    ISSN: 0021-9304
    Keywords: nanoparticles ; protein adsorption ; 2-D PAGE ; drug targeting ; colloidal drug carriers ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Plasma protein adsorption patterns on colloidal drug carriers acquired after iv administration depend on their surface characteristics and are regarded as key factors for their in vivo organ distribution. Polymeric latex particles with strongly differing surface properties were synthesized as models for colloidal drug carriers for tissue-specific drug targeting via the intravenous route. Physicochemical characterization was performed for size, surface charge density, zeta potential, and surface hydrophobicity. The interactions with human plasma proteins were studied by way of two-dimensional polyacrylamide gel electrophoresis (2-D PAGE). Considerable differences in protein adsorption on the latex particles were detected with regard to the total amount of surface-bound protein on the various particle types as well as specific proteins adsorbed, for example, fibrinogen, albumin, and a recently identified plasma glycoprotein. Possible correlations between protein adsorption patterns and the physicochemical characteristics and topography of the polymeric surfaces are shown and discussed. Knowledge about protein-nanoparticle interactions can be utilized for the rational design of colloidal drug carriers and also may be useful for optimizing implants and medical devices. © 1998 John Wiley & Sons, Inc. J Biomed Mater Res, 39, 478-485, 1998.
    Additional Material: 5 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für die chemische Industrie 13 (1900), S. 1103-1108 
    ISSN: 0044-8249
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    ISSN: 0570-0833
    Keywords: Biotechnology ; Fermentation ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The preparation of organic substances with the aid of the enzyme systems of micoorganisms has become competitive as a result of recent progress in the technology of fermentation. The relatively high cost of apparatus and the lower production capacity of microbiological plants in relation to the plants used in purely chemical processes are offset in many cases by the advantages of biological methods (reactions at conventionally inactive positions in the molecule, stereospecific substitutions, coupling of several reactions, mild reaction conditions, possible use of waste products).
    Additional Material: 10 Ill.
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  • 5
    ISSN: 0933-5137
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Effect of ZrO2 addition on mechanical and tribological properties of TiB2-ZrO2-compositesTiB2-ZrO2-composites were produced by hot-pressing in argon. The mechanical and tribological properties of the composites were investigated in relation to the amount and the type of the ZrO2 added. Addition of ZrO2 reduced the sintering temperature of the TiB2-ZrO2-composites and led to growth inhibition of the TiB2 phase. ZrO2 also increased the bending strength and fracture toughness of the composites. Tribological tests were carried out using laboratory tribometers under unlubricated oscillating sliding contact against Al2O3-, Si3N4- and SiC-counterbodies. Abrasive wear of the ceramics against 80 mesh SiC grits was studied by using an abrasive wheel test. During sliding contact the composites showed high wear resistance but caused extensive wear of the counterbodies and high friction coefficients compaired to self-mated monolithic Al2O3- and ZrO2-ceramics. Volumetric wear loss of the TiB2-ZrO2-composites due to abasive SiC grits was by a factor up to 30 lower than that of a commercial monolithic Al2O3. Wear resistance of the composites increased with decreasing amount of ZrO2 and was higher for the composites with addition of partially stabilized tetragonal ZrO2 than for those with addition of monoclinic ZrO2.
    Notes: TiB2-ZrO2-Mischkeramiken wurden durch Heißpressen hergestellt und mechanische sowie tribologische Eigenschaften in Abhängigkeit vom Volumenanteil und der Modifikation des zugegebenen ZrO2 bestimmt. Durch die Zugabe von ZrO2 konnte die zum Erreichen hoher Enddichten notwendige Preßtemperatur auf 1500°C gesenkt und das Kornwachstum des TiB2 verhindert werden. Die Mischkeramiken wiesen gegenüber reiner TiB2-Keramik, bei einer reduzierten Härte, höhere Festigkeiten und Bruchzähigkeiten auf. Die tribologischen Untersuchungen wurden unter ungeschmierter, reversierender Gleitbeanspruchung in Paarung mit Al2O3-, Si3N4- und SiC-Gegenkörpern sowie unter Furchungsbeanspruchung durch SiC-Abrasivpartikel durchgeführt. Im Gleitkontakt zeigten die Mischkeramiken einen hohen Verschleißwiderstand, führten jedoch zu einem starken Verschleiß der keramischen Gegenkörper und hohen Reibungszahlen verglichen mit selbstgepaarten, monolithischen Al2O3- und ZrO2-Keramiken. Unter Furchungsbeanspruchung durch SiC-Abrasivpartikel lag der Verschleißwiderstand der TiB2-ZrO2-Keramiken um einen Faktor biszu 30 höher als der monolithischer Al2O3-Keramik. Der Verschleißwiderstand der TiB2-ZrO2-Kermiken nahm mit abnehmendem ZrO2-Anteil zu und erreichte bei den mit teilstabilisiertem, tetragonalem ZrO2 höhere Werte als bei den mit unstabilisiertem, monoklinen ZrO2 hergestellten Mischkeramiken.
    Additional Material: 10 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    ISSN: 0044-8249
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 7
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    ISSN: 0044-8249
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 8
    ISSN: 0947-5117
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Microbial deterioration of materials - biofilm and biofouling: Biofilms in industrial water circuits. Case history: Process water system in a paper factory
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  • 9
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    ISSN: 0887-6266
    Keywords: polypropylene ; spherulite ; cocrystallization ; lamellae ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: During spherulitic crystallization of polymers, there is a tendency for low molecular weight and other less crystallizable entities to be rejected from the body of the spherulites. This rejection process causes a segregation of these species to those areas where spherulites impinge. As a result of this segregation, lamellar and spherulite boundaries have a tendency to become weak, often resulting in premature mechanical failure. The objective of this work, anthropomorphically speaking, is to develop a melt miscible blend system in which a propylene copolymer “fools” a polypropylene homopolymer into rejecting the copolymer to the spherulite boundaries as an impurity. However, once the copolymer arrives at these boundaries, the copolymer subsequently connects adjacent spherulites through cocrystallization of the propylene copolymer segments. It was found that addition of either a random ethylene-propylene copolymer or an isotactic-atactic block copolymer was able to yield the desired effect. Cocrystallization was confirmed by calorimetry, and segregation of copolymer and subsequent reinforcement at the spherulite boundaries was directly observed microscopically. Using this approach, toughness was increased with little loss in stiffness. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 2047-2056, 1998
    Additional Material: 8 Ill.
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  • 10
    ISSN: 0947-5117
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Anwendung der, „Conversion Electron Mössbauer Spectroscopy“ (C. E. M. S.) auf die Untersuchung der Inhibierung der Korrosion in Kondensatorrohren aus MessingBeschrieben wird der Aufbau eines einfachen Zählers zur Aufnahme des „Conversion Electron Mössbauer-Spektrums“ der inneren Oberfläche eines Rohres. Die Zählvorrichtung wird benutzt zur Untersuchung des Einflusses von Eisen-II-Sulfatzusatz als Inhibitor in Kühlwasser für Kondensatorrohre aus Messing. Aufgrund der Ergebnisse führt these Behandlung zur Bildung einer FeOOH-Schicht auf der inneren Rohroberfläche; die genaue Zusammensetzung der Schicht unterscheidet sich geringfügig je nach den örtlichen Verhältnissen.
    Notes: The construction is described of a simple counter for measuring the conversion electron Mössbauer spectrum of the inside surface of a tube. The counter is used to investigate the effects of adding ferrous sulphate to the cooling water of condensers with brass tubes to inhibit corrosion. It is concluded that the treatment leads to the formation on the inside of the tube of a layer of FeOOH, the exact nature of which depends slightly on the local conditions.
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