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  • 1
    Digitale Medien
    Digitale Medien
    Influence of central metal and ligand system on conduction type and charge carrier transport in phthalocyanine thin films (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 6 (1996), S. 239-244 
    Details
    ISSN: 1057-9257
    Schlagwort(e): molecular semiconductors ; organic semiconductors ; phthalocyanines ; conductivity ; thermopower ; seebeck effect ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik , Physik
    Notizen: By changing the chemical composition of phthalocyanine molecules, the electrical properties of the ensemble in the solid state can be influenced directly. This is shown for phthalocyaninatomanganese (PcMn) as compared with purely divalent central metals and for complexes in which the ligand system has been modified by either electron-withdrawing heteroatoms such as N instead of CH leading to tetrapyridotetraazaporphyrinatozinc (TPyTAPZn) or substituents such as F instead of H leading to hexadecafluorophthalocyaninatozinc (F16PcZn). The accessibility of additional oxidation states of Mn or the stabilisation of frontier orbital states by the ligand leads to a lower ionisation potential and interactions with impurities or dopant molecules are changed. A change in the observed majority carrier (n-type behaviour) is seen even under UHV conditions. Measurements of the thermoelectric power and electrical conductivity are presented of the pure films and after exposure to oxidising ambient. During film growth either island growth or a growth following the Stranski-Krastanov mechanism was observed. The comparison of the temperature dependence of thermopower and electrical conductivity leads to a discussion of the type of majority carriers, their generation as well as their transportation. For the materials investigated in this study the band model fails to explain the observed properties and a localised transport mechanism has to be considered. A transport in localised states close to the Fermi edge is discussed for TPyTAPZn and F16PcZn.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 2
    Digitale Medien
    Digitale Medien
    Stability of polymer composites as positive-temperature-coefficient resistors (1974)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 14 (1974), S. 706-716 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: This is a study of materials which are positive-temperature-coefficient resistors. Such materials, composed of conductive particles dispersed in a crystalline polymeric matrix, have been found to be of limited stability. An example is carbon black in high-density polyethylene. On repeated cycling through the anomaly temperature or on extensive heating at or above the anomaly temperature, the room temperature resistivity rises and the anomaly height falls to zero. This phenomenon has been shown to be caused by the absorption of oxygen by the polymer matrix which alters the structure, reduces the crystallinity, and induces an unusual form of crosslinking of a reversible nature.
    Zusätzliches Material: 15 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760141009
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  • 3
    Digitale Medien
    Digitale Medien
    Mass transfer and depolymerization of styrene in polystyreneThis paper was presented at the 73rd Annual Meeting of the American Institute of Chemical Engineers, Chicago, Illinois (November 20, 1980). (1981)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 21 (1981), S. 1055-1062 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: This work shows how laboratory experiments may provide parameters which are useful in modeling a commercial process of polystyrene devolatilization. Such processes often occur at temperatures where depolymerization of polystyrene to monomer may be significant. Polystyrene devolatilizers function by forming thin films of the polymer, with styrene loss by flashing and diffusion and styrene generation by depolymerization. The modeling parameters of importance are: depolymerization rate constant, monomer diffusivity, and thermodynamic equilibrium polymer-vapor partition coefficient. Typical levels of styrene in polystyrene in the last stage of devolatilization are 100 to 1000 ppm. Pressures and temperatures in the devolatilizer are often less than 10 torr and greater than 200°C. For styrene-polystyrene the desired parameters have not been reported, nor apparently measured, at the concentration, pressure and temperature levels of interest.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760211603
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  • 4
    Digitale Medien
    Digitale Medien
    Glass transition temperature as a guide to selection of polymers suitable for PTC materials (1973)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 13 (1973), S. 462-468 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: It has been shown that the only way to predict the size of the PTC effect displayed by a crystalline polymer when filled with conductive particles is through the knowledge of the glass transition point of the polymer. The size of the PTC anomaly is found to decrease sharply with rise in glass transition temperature and for a polymer to be a useful PTC material its glass transition must be below 0°C. It has not been possible to explain this relationship by any of the current theories of the PTC mechanism in filled polymers.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760130611
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  • 5
    Digitale Medien
    Digitale Medien
    A process for protein enrichment of cassava by solid substrate fermentation in rural conditions (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 29 (1987), S. 962-968 
    Details
    ISSN: 0006-3592
    Schlagwort(e): Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: An artisanal static process for protein enrichment of cassava by solid-state fermentation, developed in laboratory and tested on pilot units in Burundi (Central Africa), provides enriched cassava containing 10.7% of dry matter protein versus 1% before fermentation. Cassava chips, processed into granules of 2-4-mm diameter, are moistened (40% water content) and steamed. After cooling to 40°C, cassava is mixed with a nutritive solution containing the inoculum (Rhizopus oryzae, strain MUCL 28627) and providing the following per 100 g dry matter: 3.4 g urea, 1.5 g KH2PO4, 0.8 g MgSO4·7H2O, and 22.7 g citric acid. For the fermentation, cassava, with ca. 60% moisture content, is spread in a thin layer (2-3 cm thick) on perforated trays and slid into an aerated humidified enclosure. The incubation lasts ± 65 h. The production of protein enriched cassava is 3.26 kg dry matter/m2 tray. The effects of the variation of the nutritive solution composition and the inoculum conservation period on the protein production are equally discussed.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bit.260290807
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  • 6
    Digitale Medien
    Digitale Medien
    A channel flow analysis for porous beds moving under high G forces (1980)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 26 (1980), S. 363-371 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: An analysis is made of centrifugal flow of compacted porous beds through channels against high gas backpressure. One-dimensional compressible gas flow solutions are presented for concurrent and countercurrent solids/gas motion through the variable area channels. The physical process analyzed represents the flow through a newly developed centrifugal pump for feeding dry pulverized material against a pressure barrier. The objective of the analysis is to gain a basic theoretical understanding of this type of device. Good agreement is found between analytical predictions and test data obtained with an experimental pump feeding coal.
    Zusätzliches Material: 18 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690260306
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  • 7
    Digitale Medien
    Digitale Medien
    Solubility of isobutane and propane in polyethylene at high temperatures and low pressures (1983)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 28 (1983), S. 725-741 
    Details
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: A novel procedure was developed to measure the solubility of isobutane and propane in both low and high-density polyethylene at temperatures to 500°F (260°C) and vapor pressures from 1 to 1500 torr (33 psia). These measurements represent the first known solubility measurements at these combined extremes of pressure and temperature. Excellent agreement was found when our data were extrapolated to higher pressures and compared with data from another source. In the temperature and pressure regions of interest in this work, the linear isotherms were fit with a form of the Flory-Huggins equation. With the equation in that form we can now estimate the ratio of solubilities of two solutes in a given polymer from pure solute data only. We can also predict the absolute solubility of nonpolar solutes in polyethylene at various temperatures and pressures using only critical temperatures and acentric factors of the solutes.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/app.1983.070280227
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  • 8
    Digitale Medien
    Digitale Medien
    Addendum to construction of linearly independent relativistic symmetry orbitals for finite double-point groups including time-reversal symmetry (1997)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 61 (1997), S. 929-933 
    Details
    ISSN: 0020-7608
    Schlagwort(e): Chemistry ; Theoretical, Physical and Computational Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: In a previous article [J. Meyer, Int. J. Quantum Chem. 33, 445 (1988)], the formalism for the construction of linearly independent relativistic symmetry-adapted molecular basis functions under consideration of time-reversal symmetry was published. We present here an addition and correction of the application of time reversal on the construction. This new theory is now applicable to all double-point groups, including the icosahedral groups not considered so far. © 1997 John Wiley & Sons, Inc.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
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  • 9
    Digitale Medien
    Digitale Medien
    Polysilane. VI. Bildung von Polysilanen bei sterisch gehinderten Grignard-Reaktionen (1961)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 313 (1961), S. 107-116 
    Details
    ISSN: 0044-2313
    Schlagwort(e): Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Beschreibung / Inhaltsverzeichnis: The GRIGNARD reaction between silicon halides and alkyl-Mg-halides with steric hindering alkyl groups does not run in the usual manner. Thus from SiBr4 and secondary or tertiary butyl—MgBr only the corresponding butyl-tribromosilanes (C4H9)SiBr3 could be prepared in low yields. To a great extent, there are side reactions which produce silanes with Si—H-bonds by developing butene (C4H8) and high molecular polysilanes with, Si—Si-bonds by cleaving off octane (C8H18).
    Notizen: Die Grignard-Reaktion zwischen Silicium-halogeniden und Alkyl-Mg-halogeniden mit sterisch hindernden Alkylgruppen verläuft anormal. So konnten aus SiBr4 und sekundärem oder tertiärem Butyl—MgBr nur die entsprechenden Butyl-tribrom-silane (C4H9)SiBr3 in geringen Ausbeuten gewonnen werden. Es finden in großem Umfange Nebenreaktionen statt, die unter Abspaltung von Buten(C4H8) zu Silanen mit Si—H-Bindungen, sowie unter Entwicklung von Octan (C8H18) zu hochmolekularen Polysilanen mit Si—Si-Bindungen führen.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/zaac.19613130109
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  • 10
    Digitale Medien
    Digitale Medien
    Structure elucidation of a Pyoverdin Produced by Pseudomonas aeruginosa ATCC 27 853 (1993)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 335 (1993), S. 83-87 
    Details
    ISSN: 0941-1216
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The primary structure of a pyoverdin (Pa TII) isolated from an iron deficient culture medium of Pseudomonas aeruginosa ATCC 27 853 has been elucidated by spectroscopic methods and degradation studies. Total assignment of 1H and 13C resonances as well as sequential information were achieved by two-dimensional NMR techniques: HOHAHA1, NOESY, HSQC and HMBC. The structure consists of the common pyoverdin chromophore 5-amino-2,3-dihydro-8,9-dihydroxy-1H-pyrimido [1,2-a]quinoline-1-carboxylic acid with succinic acid bound amidically to its amino group and the carboxyl group linked to the N-terminus of D-Ser-D(CHO) OHOrn-L-Orn-Gly-D-aThr-L-Ser-L-cOHOrn. According to the short-hand nomenclature suggested in [2, 3] the pyoverdin may be described as pyoverdin-Q-so′ OGtaSo′*-SUC.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/prac.19933350113
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