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  • 1
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 3 (1957), S. 395-404 
    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: 15 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 22 (1978), S. 497-510 
    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 thermal decomposition of fibrous cellulose powder from 275° to 340°C has been studied by thermogravimetry, scanning electron microscopy, krypton adsorption, and gas-chromatographic analysis of the gaseous products arising from pyrolysis in various oxidizing and inert atmospheres. The reaction kinetics fit a phase boundary model where the rate is controlled by the movement of an interface through a cylindrical particle and the principal kinetic parameters fit a compensation curve described previously for the decomposition of wood products. An explanation of the physical mechanism of pyrolysis is proposed which is consistent with the observed rate data and the structural changes observed by scanning electron microscopy.
    Additional Material: 10 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 325 (1963), S. 191-195 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Using a dropping Bi electrode, the polarographic behaviour of heavy-metal ions in the molten LiCl—KCl eutectic has been investigated at 450°C. The half-wave potentials are communicated. An estimation of the Nernst factors shows that the Heyrovsky-Ilkovič equation is valid.
    Notes: Unter Verwendung einer tropfenden Wismutelektrode wird das polarographische Verhalten von Schwermetallionen im geschmolzenen LiCl—KCl-Eutektikum bei 450°C untersucht. Es werden die Halbstufenpotentiale ermittelt und an Hand der Nernst-Faktoren gezeigt, daß auch hier die Heyrovsky-Ilkovičsche Gleichung gilt.
    Additional Material: 6 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 409 (1974), S. 106-114 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Katalytische Oxydation von Wasserstoff an NickeloxidenDie katalytische Oxydation von Wasserstoff an hochdispersen sowie gesinterten Nickeloxiden wurde mit einer statischen Methode untersucht und das Vorhandensein zweier verschiedener kinetischer Bereiche festgestellt. Zwischen 0 und 100°C war die anfängliche katalytische Aktivität nicht stationär, und eine stark vergiftende Wirkung des Reaktionsproduktes wurde bei allen Temperaturen bis zu 250°C beobachtet. Die Aktivierungsenergie der Reaktion, die auf den anfänglichen Reaktionsgeschwindigkeiten auf frisch entgasten Oxidoberflächen basiert, wies den kleinen Wert von 1-2 kcal . mol-1 bei beiden Präparaten auf. Im Temperaturbereich zwischen 250 und 350°C wurde eine stationär katalytische Aktivität beobachtet, und die Aktivierungsenergie der Reaktion lag bedeutend höher bei 12-15 kcal . mol-1.Der Wechsel in der Aktivierungsenergie wird mit der Wirkung von unterschiedlichen Sauerstoffarten der Katalysatoroberfläche, die in beiden Temperaturbereichen verschiedene Aktivitäten bei der Reaktion aufweisen, diskutiert. Eine Analogie zwischen der Kohlen- oxid- nnd Wasserstoffoxydation an Nickeloxid wird festgestellt sowie ein Kompensationseffekt für eine Reihe von Oxydationsreaktionen gezeigt.
    Notes: The catalytic oxidation of hydrogen on highly-dispersed and sintered nickel oxides has been studied by a static method and the existence of two different kinetic rcgions established. Between 0 and 100°C the initial catalytic activity was not ionary and a strong poisoning effect of the reaction product was observed at all temperatnres up to 250°C. The activation energy of the reaction based on the initial reaction rates on freshly- outgassed oxide surfaces had a low value of 1-2 kcal. mole-1 with both preparations. Between 250 and 350°C stationary catalytic activity was observed and the activation energy of the reaction was significantly higher, 12-14 kcal . mole-1.The change of the activation energy is discussed in terms of the participation in the reaction of oxygen species in the catalyst surface layer which have different reactivities in the two temperature regions. A close analogy is noted between the carbon monoxide and hydrogen oxidation reactions on nickel oxide and a compensation effect is illustrated for a series of oxidation reactions on the oxide.
    Additional Material: 6 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 325 (1963), S. 181-190 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Polarographic investigations in molten salt mixtures (NaCl—KCl, mole ration 1:1, 735°C; LiCl—KCl, 59 mole-% LiCl, 450°C) using W. microelectrodes and reducing heavymetal ions (sec „Inhaltsübersicht“) are described. The dependence of the half-wave potentials and diffusion currents on electrode material and surface, resp., on temperature and concentration is discussed. The polarogrphic determination of the investigated ions is possible from 10-4 to 10-2 mole/kg.
    Notes: Polarographische Untersuchungen in Schmelzen von NaCl—KCl-Gemischen (Molverhältnis 1:1) bei 735°C sowie LiCl—KCl-Gemischen (59 Mol-% LiCl, 41 Mol-% KCl) bei 450°C mit Wolfram-Mikroelektroden werden beschrieben. Die Halbstufenpotentiale von Co++, Ni++, Cu+, Zn++, Cd++, Fe++, Pb++, Tl+ und U4/U3+ sind vom Elektrodenmaterial abhängig, wie sich aus dem Vergleich mit an Platin gemessenen Werten ergibt. Die Veränderungen der Halbstufenpotentiale sowie des Diffusionsstromes mit der Depolarisatorkonzentration, der Temperatur und der Elektrodenoberfläche werden untersucht und diskutiert. Die polarographische Bestimmung der genannten Ionen auch nebeneinander gelingt in dem Konzentrationsbereich von etwa 10-4 bis 10-2 Mol pro kg.
    Additional Material: 12 Ill.
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  • 6
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 7
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 48 (1960), S. 17-25 
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Promoted preformed solids catalyze polymerization of ethylene and propylene and formation of copolymers of ethylene with such olefins as propylene and butene-1. The structure of the copolymers helps explain how they are formed and their properties. Kinetic studies alone do not distinguish between polymerization mechanisms involving either anionic centers or ion-radicals. Structural studies of ethylene-propylene copolymers of low propylene content show that they contain isolated propylene units in accord with the ion-radical theory of polymerization in a chemisorbed layer. Isolated short sidechains, so introduced, reduce density and increase flexibility. They give copolymers with flow properties more like those of linear polyethylenes than those of branched polyethylenes with long sidechains. Furthermore, they interfere with recrystallization and crystal growth; the resulting polymers have better stress-crack resistance and form clearer films.
    Additional Material: 2 Ill.
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  • 9
    ISSN: 0044-2313
    Keywords: Oxoniobates ; manganese oxoniobate, MnNb2O6 ; chemical vapour transport ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Contributions on the Thermal Behaviour of Oxoniobates of the Transition Metals. II. The Chemical Vapour Transport of MnNb2O6 with Cl2 or NH4Cl. Experiments and CalculationsCrystals of MnNb2O6 were obtained by chemical transport reactions in a temperature gradient (1020°C → 960 °C) using Cl2 (added as PtCl2) or NH4Cl as transport agent. As a result of thermodynamic calculations the evaporation and deposition of MnNb2O6 in the presence of Cl2 can be expressed by the endothermic equilibrium (1).The endothermic reaction (2) is responsible for the migration of MnNb2O6 if NH4Cl is used as transport agent.Assuming ΔH°298(MnNb2O6, s) = -567.6 kcal/mol a satisfying agreement between thermodynamic calculations and experimental results can be reached.
    Notes: Kristalle von MnNb2O6 ließen sich mit Cl2 (Zusatz von PtCl2) oder NH4Cl als Transportmittel im Temperaturgefälle (1020°C → 960° C) abscheiden. Wie thermodynamische Modellrechnungen zeigen, ist für den Transport mit Cl2 das endotherme Gleichgewicht (1) bestimmend.Bei Zugabe von NH4Cl ist die endotherme Reaktion (2) für die Wanderung von MnNb2O6 im Temperaturgradienten verantwortlich.Experimente und Modellrechnungen stimmen gut überein, wenn δBH°298(MnNb2O6, f) zu -567, 6 kcal/mol abgeschätzt wird.
    Additional Material: 1 Ill.
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  • 10
    ISSN: 0044-2313
    Keywords: Zirconium, hafnium niobates ; preparation ; phase analysis ; electron microscopy ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Contributions to the Investigation of Inorganic Non-Stoichiometric Compounds. XLII. Preparation and Electron Microscopic Investigation of α-MNb24O62 and MNb52O132 (M = Zr, Hf)The new ternary oxides α-HfNb24O62 and HfNb52O132 were obtained by oxidizing corresponding mixtures of HfO2/NbO2 and subsequent heating at 1150°C, a temperature which is unusually low for reactions in this system. In contrast, α-ZrNb24O62 could not be obtained in this way. Instead, samples with a certain amount of this compound were synthesized in a manner described previously, but they always contained considerable amounts of the β-Modification, too. HRTEM-investigations showed all compounds, mentioned above, to have block structures. The ideal structure of HfNb52O132 corresponds to the wellknown NbOx-phase Nb53O132; α-ZrNb24O62 and α-HfNb24O62 are isostructural to Nb25O62. Additionally, there exist corresponding relationships to TiNb52O132 and TiNb24O62. Samples with a starting composition of ZrO2/NbO2 = 1:24 were microheterogenous and contained large amounts of the hybrid phase ZrNb38O97.
    Notes: Die neuen ternären Oxide α-HfNb24O62 und HfNb52O132 konnten durch Oxidation entsprechend zusammengesetzter Gemenge HfO2/NbO2 und anschließendes Glühen bei 1150°C, einer für Umsetzungen dieser Art ungewöhnlich niedrigen Temperatur, dargestellt werden. α-ZrNb24O62 war nicht auf diese Weise, jedoch auf einem von uns früher beschriebenen Wege (Mischfällungen) nur im Gemenge mit der β-Modifikation zugänglich. Wie die Untersuchung mit der hochauflösenden Durchstrahlungselektronenmikroskopie zeigt, besitzen die Verbindungen Blockstrukturen. Das Bauprinzip von HfNb52O132 entspricht den Phasen TiNb52O132 und Nb53O132, α-HfNb24O62 und α-ZrNb24O62 sind mit TiNb24O62 und Nb25O62 isostrukturell. Ausgehend von ZrO2/NbO2 = 1:24 ergab die Oxidation mikroheterogene Proben mit einem großen Anteil der Hybridphase ZrNb38O97.
    Additional Material: 5 Ill.
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