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  • Chemical Engineering  (70)
  • Inorganic Chemistry  (32)
  • Wiley-Blackwell  (102)
  • 1995-1999  (102)
  • 1995  (102)
  • 1
    ISSN: 0044-2313
    Schlagwort(e): Vanadium(IV) complexes ; syntheses ; crystal structures ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Beschreibung / Inhaltsverzeichnis: Reactions and Thermal Behaviour of Nonoxo Vanadium(IV) Complexes. Crystal Structures of Methoxo-oxo[thenoyltrifluoroacetone-salicylhydrazonato(2-)]vanadium(V) and Methoxo-oxo[benzoylacetone-salicylhydrazonato(2-)]vanadium(V)The persistence of non-oxo vanadium(IV) complexes in dichlormethane/methanol/water solutions was studied by UV/VIS spectroscopy. The reaction products methoxo-oxo-[thenoyltrifluoroacetone-salicylhydrazonato(2-)]vanadium(V) and methoxo-oxo[benzoylacetone-salicylhydrazonato(2-)]vanadium(V) were isolated and characterized by X-ray analysis. The thermal behaviour of non-oxo vanadium(IV) complexes was checked.
    Notizen: Die Beständigkeit oxofreier Vanadium(IV)-Komplexe mit dreizähnigen diaciden Liganden in Dichlormethan/Methanol/Wasser wurde UV/VIS-spektroskopisch untersucht. Als Reaktionsprodukte wurden Methoxo-oxo-[thenoyl-trifluoraceton-salicylhydrazonato(2-)]vanadium(V) sowie Methoxo-oxo-[benzoylaceton-salicylhydrazonato(2-)]vanadium(V) isoliert und röntgenstrukturanalytisch charakterisiert. Das thermische Verhalten der oxofreien Vanadium(IV)-Komplexe wurde analysiert.Methoxo-oxo-[thenoyltrifluoraceton-salicylhydrazonato(2-)]-vanadium(V), Raumgruppe P21/a2, Z = 4, 3 124 beobachtete unabhängige Reflexe, R = 0,0579, Gitterabmessungen bei 25°C; a = 800,0(2) pm, b = 2 027,3(6) pm, c = 1 165,0(3) pm, β = 109,03(2)° Methoxo-oxo-[benzoylaceton-salicylhydrazonato(2-)]vanadium(V) Raumgruppe P21/c, Z = 4, 2 312 beobachtete unabhängige Reflexe, R = 0,031, Gitterabmessungen bei 25°C: a = 1 122,6(1) pm, b = 772,96(9) pm, c = 2 021,2(4) pm, β = 95,32(1)°.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
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  • 2
    ISSN: 0044-2313
    Schlagwort(e): Manganese(IV) Chelates, Salicylaldehyde benzoylhydrazone and salicylhydrazone ; Mass Spectra ; Crystal Structure, Acetylacetonato-salicylaldehydebenzoylhydrazonato(2-)-methanol-manganese(III) ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Beschreibung / Inhaltsverzeichnis: Manganese(IV) Complexes with Tridentate Diacidic Ligands. Crystal Structure of Acetyl-acetonato-salicylaldehydebenzoylhydrazonato(2-)-methanol-manganese(III)The manganese(IV) chelates of salicylaldehyde benzoylhydrazone and salicylaldehyde salicylhydrazone were synthesized by ligand exchange reactions using bis(acetylacetonato)manganese(II), tris(acetylacetonato)manganese(III) as well as manganese(III) acetate. The brown complexes show the expected molecular ions in the APCI mass spectra. As an intermediate compound acetyacetonato-salicylaldehydebenzoylhydrazonato(2-)-methanol-manganese(III) was isolated and characterized by X-ray structural analysis. Crystallographic data see “Inhaltsübersicht”.
    Notizen: Durch Ligandenaustauschreaktion von Bis(acetylacetonato)mangan(II) und Tris(acetylacetonato)mangan(III) bzw. Mangan(III)-acetat mit Salicylaldehydbenzoylhydrazon und -salicylhydrazon wurden die Mangan(IV)-Chelate dieser Liganden dargestellt. Die braunen Verbindungen zeigen im APCI-positiv Massenspektrum die erwarteten Molekülionen. Für das Zwischenprodukt Acetylacetonato-salicylaldehydbenzoylhydrazonato(2-)-methanol-mangan(III) wurde die Kristall- und Molekülstruktur bestimmt: Gitterabmessungen bei 293 K; a = 754,3(2) pm, b = 1 027,3(6) pm, c = 1 357,4(5) pm, α = 79,64(4)°, β = 76,51(3)°, γ = 70,45(4)°, Raumgruppe P1 (Nr. 2), Z = 2, 3297 unabhängige Reflexe, R = 3,84%.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 3
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 621 (1995), S. 671-674 
    ISSN: 0044-2313
    Schlagwort(e): N,N,N′,N′-Tetrakis(2-hydroxybenzyl)ethylenediamine ; Complexes of Titanium(IV), Vanadium(IV), Manganese(IV), Tin(IV) ; Mass Spectra ; Mössbauer Data ; Crystal Structure ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Beschreibung / Inhaltsverzeichnis: Complexes with N,N,N′,N′-Tetrakis(2-hydroxybenzyl)ethylenediamine (H4tben). Crystal Structure of Ti(tben)The complexes of N,N,N′,N′-tetrakis(2-hydroxybenzyl)-ethylenediamine with titanium(IV), vanadium(IV), manganese(IV), and tin(IV) were synthesized and characterized by mass spectrometry. The Mössbauer date were evaluated for the tin compound. The molecular structure of the titanium(IV) complex was determined by X-ray structural analysis, crystallographic data see “Inhaltsübersicht”.
    Notizen: Es wurden die Komplexe von N,N,N′,N′-Tetrakis(2-hydroxybenzyl)ethylendiamin mit Titan(IV), Vanadium(IV), Mangan(IV) und Zinn(IV) hergestellt und massenspektrometrisch charakterisiert. Für die Zinn-Verbindung wurden die Mössbauer-Daten ermittelt. Die Molekülstruktur des Titan(IV)-Komplexes wurde röntgenstrukturanalytisch bestimmt. N,N,N′,N′-Tetrakis(2-hydroxybenzyl)ethylendiaminato(4-)titan(IV): Raumgruppe P21/c (Nr. 14), Z = 4, 3949 Zahl der beobachteten Intensitäten, R = 0,0539, Gitterabmessung bei 20°C; a = 10,447(3) Å, b = 20,668(5) Å, c = 13,420(3) Å, b̃ = 101,93(5) Å
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
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  • 4
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 1874-1888 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A detailed chemical kinetics model comprising 148 reversible elementory reactions for the supercritical water oxidation (SCWO) of methane, methanol, carbon monoxide and hydrogen was developed. Rate constants were taken from previous critical evaluations. The Lindemann model, at times modified with a broadening parameter, was used to account for the effects of pressure on the kinetics of unimolecular reactions. Model predictions were compared with published experimental SCWO kinetics data for 450-650°C and 240-250 atm. The model correctly predicted global reaction orders for all four fuels to within their uncertainties. In addition, the model correctly predicted that the global reaction orders for O2 during methanol and hydrogen oxidation were essentially zero, and that the O2 concentration had the greatest effect on the methane oxidation rate. The pseudo-first-order rate constants predicted by the model were consistently higher than the experimental values, but the global activation energies were predicted correctly for methane oxidation and for CO and H2 oxidation at high temperatures. The model's predictions generally became worse as the temperature decreased toward the critical point of water. A sensitivity analysis revealed that fewer than 20 elementaty reactions largely controlled the oxidation kinetics for the compounds studied. Nearly half of these reactions involved HO2, which is an important free radical for SCWO. Quantitative agreement with the experimental methane conversions was obtained by adjusting the preexponential factors for three elementary reactions within their uncertainties. It could also be obtained by using the JANAF value (0.5 kcal/mol) for the standard heat of formation of HO2, but this value is lower than other recently recommended values.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 1005-1009 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Partial specific volumes at 25°C are reported for α-chymotrypsinogen in aqueous solutions containing NaCl, citrate, and/or polyethylene gycol (PEG) over a range of protein concentrations. The concentration dependence of the partial specific volume can be either positive or negative, depending on the solvent. For example, the partial specific volume increases with increasing protein concentration in NaCl/citrate solutions at high salt concentrations, and decreases with increasing protein concentration in solutions containing PEG. Kirkwood-Buff solution theory has been applied to interpret these results, and it was found that the concentration dependence is determined by two factors: (1) the effective or solvent-averaged interactions between protein molecules in solution, and (2) three-body protein - protein - solvent and protein - solvent - solvent interactions. An approach is proposed for the experimental determination of both contributions that involves measuring osmotic pressures and volumetric properties of dilute to concentrated protein solutions.
    Zusätzliches Material: 1 Tab.
    Materialart: Digitale Medien
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  • 6
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 1723-1778 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Supercritical fluids posses properties that make them attractive as media for chemical reactions. Conducting chemical reactions at supercritical conditions affords opportunities to manipulate the reaction environment (solvent properties) by manipulating pressure, to enhance the solubilities of reactants and products, to eliminate interphase transport limitations on reaction rates, and to integrate reaction and separation unit operations. Supercritical conditions may be advantageous for reactions involved in fuels processing, biomass conversion, biocatalysis, homogeneous and heterogeneous catalysis, environmental control, polymerization, materials synthesis, and chemical synthesis. Moreover, supercritical fluids can be used profitably in fundamental chemical investigations of intermolecular interactions and their influence on chemical processes. Work on chemical reactions in and with supercritical fluids is reviewed. We discuss both fundamental studies and applications of reactions at supercritical conditions, with focus on work published after 1985.
    Zusätzliches Material: 43 Ill.
    Materialart: Digitale Medien
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  • 7
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 12-22 
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: An analytical approach to the problem of steady-state, axisymmetrically disperesed, bubbly flow in pipes based on a zero equation turbulence model is discussed. The formulation incorporates recent experimental observations and introduces the effect of bubble size in a rudimentary way. The two-phase mixture is modeled as a variabledensity single fluid assuming an empirical void distribution family. The turbulent shear stress is formed from the contributions of both the velocity and density variation, and the solution of the resulting Reynolds-type equation yields the velocity profile of the flow. Predicted void fraction and velocity distributions agree well with experimental measurements. The main objective of the model is to predict the friction multiplier with minimal computational effort. The velocity profiles of this model agree reasonably well with experiments. Predictions for the friction multiplier are compared to six known and widely used correlations, as well as to experimental data. All the correlations severely underpredict the friction multiplier in the disperesed bubbly flow regime, while the results of our model agree well with the measurements, within the range of its validity.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 8
    Digitale Medien
    Digitale Medien
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 35 (1995), S. 151-156 
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Thermal diffusivity of high density polyethylene (HDPE) was studied over a wide range of temperatures (25 to 200°C) by melting powdered HDPE in a cylindrical mold at several pressures (101.3 to 5065 KPa gage) and recording the temperature profiles at several radial positions. The energy equation was solved numerically for cylindrical geometry. The thermal diffusivity of HDPE was fit as a function of temperature, porosity, and pressure.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
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  • 9
    Digitale Medien
    Digitale Medien
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 35 (1995), S. 1282-1289 
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The creep behavior of polymers depends on the physical age of the material at the time of stress application. Creep curves shift to longer times for more highly aged material and, in poly(vinyl chloride), (PVC), this can be modeled by an empirical equation in which the magnitude of an effective mean retardation time parameter is dependent upon, and increases with, the age of the polymer. Creep compliances for PVC also depend on the magnitude of the applied stress when this exceeds about 4 MPa. This nonlinear behavior is caused, at short creep times, by a reduction in the value for the retardation time parameter on application of the creep stress. Specimens appear therefore to be initially de-aged by elevated stresses. Subsequently, this parameter increases with creep time implying that physical aging has been reactivated, but the rate of increase also depends on the stress level. These influences of elevated stresses can be described by an extension of the creep model, and parametric expressions have been derived which relate creep compliance values to time, stress, and the age of the polymer. It is shown how the parameters can be determined from a short series of creep experiments and thus how creep deformations can be calculated over wide ranges of time, stress, and age.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
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  • 10
    Digitale Medien
    Digitale Medien
    Brookfield, Conn. : Wiley-Blackwell
    Polymer Composites 16 (1995), S. 319-324 
    ISSN: 0272-8397
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Maschinenbau
    Notizen: This paper deals with the conductivity of binary polymer composites filled with an electronically conductive material. A “dynamic cluster model” is offered to describe the conductivity of such polymer composites in the highly filled region, i.e. above the percolation threshold. The model is based on the following assumptions: 1a modification of the basic statistical percolation equation, i.e. σ (ϕ-ϕc)t, where t = 1.6 to 1.9, should be applied for all systems in the highly filled region, although application is limited to the range ϕ = ϕc + Δϕ, Δϕ ⇒ 0 in the strict statistical percolation approach;2the most important modifications with respect to the basic equation of the statistical percolation theory are (a) the use of a constant teff, including a constant part t1 (resembling “t” in the basic statistical percolation approach) and a variable part t2 (depending on the filler concentration ϕ of the specific mixture) and(b) the definition of ϕc as the filler concentration where a perfect three-dimensional network of the conductive phase has been established. This idea has been adopted from the bond-percolation approach of Aharoni;3the resulting equation should include parameters of specific polymer composites.The generalized equation σ = f(ϕ) is used to calculate the maximum possible conductivity of a certain mixture as well as the dependence of σ on the filler content.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
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