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  • FLUID MECHANICS AND HEAT TRANSFER  (5)
  • Inorganic Chemistry  (5)
  • 1
    Electronic Resource
    Electronic Resource
    Kinetics and mechanism of Oxidation of Diaqua(nitrilotriacetato)cobaltate(II) by Peroxodisulfate ion in aqueous acidic solutions (1981)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 473 (1981), S. 224-230 
    Details
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Kinetik und mechanismus der oxydation von diaqua(nitrilotriacetato)-cobaltat(II) durch peroxodisulfat in wäßrigsauren lösungenDie Kinetik der Oxydation von CoII-NTA durch Peroxodisulfat (S2O82-) in saurem Medium photometrisch untersucht. Die Stöchiometrie der Reaktion ist: 2CoII-NTA- + S2O82- → 2CoIII-NTA + 2SO42-. Im pH-Bereich 4,2 - 5,4 folgt die Reaktion dem Geschwindigkeitsgesetz [H+] und [S2O82-] sind die Wasserstoff- bzw. Peroxodisulfationen-Konzentration, KH ist die Dissoziationskonstante des CoII(NTA)H und kH ist die Geschwindigkeitskonstante für den Elektronenübergang. Die Aktivierungsparameter werden mitgeteilt und der mögliche Mechanismus für den Elektronenübergang wird diskutiert.
    Notes: The kinetics of oxidation of CoII - NTA by the peroxodisulfate ion (S2O82-) in acidic media have been studied spectrophotometrically. The stoichiometry of the reaction is 2[CoII(NTA)]- + S2O82- → 2CoIII-NTA + 2SO42-. In the pH range (4.2 - 5.4), the reaction fol- lows the rate law, where [H+] and [S2O82-] denote the hydrogen ion and peroxodisulfate ion concentration respectively, KH is the pre-equilibrium protonation constant, and kH is the rate constant for the electron-transfer process. Activation parameters are reported and possible mechanism for the electron-transfer process in discussed.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19814730226
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  • 2
    Electronic Resource
    Electronic Resource
    Dissociation of Tris-Oxinatochromium(III) in acid medium: Evalutation of equilibrium constants (1970)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 374 (1970), S. 108-112 
    Details
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Es wurden die Gleichgewichtskonstanten der stufenweisen Dissoziation von Chrom(II1)-tris-oxinat in saurer 50 vol.-proz. Alkohol- Wasser-Lösung nach der BJERRUM-Methode ermittelt. Da auch bis herunter zu pH ≍ 1,9 keine weitere Disso-ziation als bis zum Mono-oxinatokomplex erfolgt, konnten nach dieser Methode K′ und K″ der beiden ersten Dissoziationsstufen bestimmt werden (Daten s. “Abstract”).
    Notes: The equilibrium constants for the stepwise dissociation of tris-oxinato-chromium(II1) in 50 per cent (v/v) aqueous-alcoholic acidic medium have been evaluated from pH measurements using BJERRUM's method. Even down to a pH ca. 1.9 no perceptible dissociation beyond the stage of the mono-oxinato complex takes place; hence only the equilibrium constants for the first two stages, namely tris- to bis- and bis- to mono-, could be evaluated by this method. At 35°C (μ, 0.1) the values are \documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{*{20}c} {{\rm K' = }{{\left[{{\rm CrL}_{\rm 2}^{\rm + } } \right]\left[{{\rm LH}} \right]} \mathord{\left/ {\vphantom {{\left[{{\rm CrL}_{\rm 2}^{\rm + } } \right]\left[{{\rm LH}} \right]} {\left[{{\rm CrL}_{\rm 3} } \right]}}} \right. \kern-\nulldelimiterspace} {\left[{{\rm CrL}_{\rm 3} } \right]}}\left[{{\rm H}^{\rm + } } \right] = 6.6 \cdot 10^{ - 3} } \hfill \\ {{\rm K'' = }\left[{{\rm CrL}^{{\rm 2 + }} } \right]{{\left[{{\rm LH}} \right]} \mathord{\left/ {\vphantom {{\left[{{\rm LH}} \right]} {\left[{{\rm CrL}_{\rm 2}^{\rm + } } \right]}}} \right. \kern-\nulldelimiterspace} {\left[{{\rm CrL}_{\rm 2}^{\rm + } } \right]}}\left[{{\rm H}^{\rm + } } \right] = 2.5 \cdot 10^{ - 4} } \hfill \\\end{array} $$\end{document} where LH = oxine (8-quinolinol), C9H7NO.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19703740116
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  • 3
    Electronic Resource
    Electronic Resource
    Kinetics and mechanism of dissociation of bis(biguanide)-Palladium(II) Ion in HCl—NaCl Medium (1972)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 393 (1972), S. 295-300 
    Details
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Kinetik und Mechanismus der Dissoziation des Bis(Biguanid)palladium(II)-Ions in HCl-NaCl-Lösungen.Die Kinetik der stufenweisen Dissoziation des Bis(biguanid)-palladium(II)-Ions in HCl-NaCl-Lösungen wurde spektrophotometrisch untersucht. Der erste Schritt in schwach saurer Lösung (0,01-0,1 m HCl) führt zur Bildung von Dichloromonobiguanid-palladium(II), der zweite Schritt in stärker saurer Lösung (0,15-0,4 m HCl) zum Tetrachloropalladat(II)-Ion. Bei jeder Stufe liegen zwei Konkurrenzreaktionen vor, eine von erster Ordnung, die andere von zweiter Ordnung.Die einzelnen Geschwindigkeitskonstanten und die entsprechenden Werte von ΔH≠ und ΔS≠ wurden ermittelt, ein möglicher Reaktionsmechanismus wird diskutiert.
    Notes: The kinetics of the stepwise dissociation of bis(biguaniide)palladium (II) ion in HCl - NaCl media have been studied spectrophotometrically. The first step leads to the formation of dichloromono(biguanide)palladium(II) at low acid concentrations (0.01-0.1 M HCl); the second step leads to the formation of tetrachloropalladate(II) ion at higher acid concentrations (0.15-0.4 M HCl). There are two concurrent reaction paths in each step, one of which is first order with respect to both H+ and Cl- ion concentrations, while the other is second order with respect to both. The individual rate constants have been evaluated, as well as the corresponding activation parameters, ΔH≠ and ΔS≠, and possible mechanisms have been discussed.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19723930313
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  • 4
    Electronic Resource
    Electronic Resource
    Kinetics and Mechanism of Formation of Tetrahaloplatinate(II) Ion in the Reactions of Bis (oxalato)-platinate(II) Ion with Chloride and Bromide Ions in Acid Media (1973)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 401 (1973), S. 189-194 
    Details
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Kinetik und Mechanismus der Bildung des PtX42- -Ions bei den Reaktionen des Bis(oxalato) platin(II)-Ions mit Chlorid- und Bromid-Ionen in wäßrigem MediumDie Geschwindigkeit der Überführung des Bis(oxalato)platin(II)-Ions, Pt(Ox)22-, in das Tetrahalogenoplatin(II)-Ion, PtX42- (X = Cl, Br), in saurem, die Halogenid-Ionen enthaltendem Medium wurde spektroskopisch untersucht. Das beobachtete Geschwindigkeitsgesetz folgt: {k′ + k″[H+]} [X-][Pt(Ox)22-]. Die Werte für k′ und k″ wurden ermittelt. Die Ergebnisse stehen mit einem Mechanismus in Übereinstimmung, bei dem die Assoziation des X- am Pt(Ox)22- gefolgt von der Dissoziation eines Oxalat-Liganden auf von H+-Ionen unabhängigen bzw. abhängigen Wegen angenommen wird. Die schnelle Anlagerung von X- an Pt(Ox)X- ergibt ein Zwischenprodukt Pt(Ox)X22-, bei welchem das Oxalat schnell durch X--Ionen zum PtX22- ersetzt wird unter dem Transeinfluß der schon gebundenen X--Liganden.
    Notes: The rate of transformation of bis(oxalato)platinate(II) ion, Pt(Ox)22-, into tetrahaloplatinate(II) ion, PtX42-, in acid media containing the halide ion (X- = Cl-, Br-) has been investigated spectrophotometrically. The observed rate law is: Rate = {k′ + k″[H+]} [X-][Pt(Ox)22-]. Activation parameters corresponding to k′ and k″ have been evaluated. The results are consistent with a mechanism which involves association of X- with Pt(Ox)22- followed by dissociation of an oxalate ligand through acid independent and acid dependent paths. Fast addition of X- to the Pt(Ox)X- gives an intermediate Pt(Ox)X2-2 from which the oxalate is replaced in a fast step by X- ions under the trans influence of the bound X- ligands forming the product PtX42-.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19734010210
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  • 5
    Electronic Resource
    Electronic Resource
    Spectrophotometric (U.V.) investigation on Metal Biguanidinium Complexes (1974)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 406 (1974), S. 124-128 
    Details
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: UV-spektroskopische Untersuchung von Metall-Biguanidin-KomplexenAus der UV-spektroskopischen Untersuchung einer Reihe von Metall-Biguanidinen wurde versucht, eine Wechselwirkung zwischen dem vollem Liganden-Orbital und dem leeren Metall-Orbital zu finden, das zum Ansteigen der Delokalisierung des Elektronensystems der ganzen Molekel führen könnte. Diese Art der Wechselwirkung könnte einen aromatischen Charakter im Metall-Biguanidin-Ring hervorrufen. Der benzoide Charakter der Metall-Acetylacetonate stellt eine Parallele zu dem der Metall-Biguanidine dar. Die Untersuchung der Metall-Biguanidine im UV zeigt, daß es klare Hinweise für die Überlappung der Liganden- und Metall-Orbitale gibt, die mit einer Verschiebung der Absorptionsbanden verbunden ist.
    Notes: From the U.V. spectra study of series of metal biguanides, attempt has been made to find out any interaction between the filled ligand orbital with the vacant metal orbital which may give rise to delocalisation of electron system over the whole complex molecule. This type of interaction may develop aromatic character in metal biguanide ring. The benzenoid character of the metal acetylacetonate can be cited as parallel to that of the metal biguanide. The U.V. study of metal biguanides concludes that there is a definite indication of the suggested overlap of the ligand and metal orbitals with consequent shifting of absorption bands with different substitutions.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19744060118
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  • 6
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    Development of an integrated BEM approach for hot fluid structure interaction (1990)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A comprehensive boundary element method is presented for transient thermoelastic analysis of hot section Earth-to-Orbit engine components. This time-domain formulation requires discretization of only the surface of the component, and thus provides an attractive alternative to finite element analysis for this class of problems. In addition, steep thermal gradients, which often occur near the surface, can be captured more readily since with a boundary element approach there are no shape functions to constrain the solution in the direction normal to the surface. For example, the circular disc analysis indicates the high level of accuracy that can be obtained. In fact, on the basis of reduced modeling effort and improved accuracy, it appears that the present boundary element method should be the preferred approach for general problems of transient thermoelasticity.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-187675 , NAS 1.26:187675
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  • 7
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    A time-dependent incompressible viscous BEM for moderate Reynolds numbers (1991)
    In:  Other Sources
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    Publication Date: 2019-07-12
    Description: The boundary element method is applied to transient viscous incompressible flow. The time-domain formulation allows a boundary-only solution for linear Stokes flow. For higher speed flows in which the nonlinear convective effects cannot be ignored, a volume integral must be retained. However, the introduction of reference velocities often limits the nonlinear region to the vicinity of obstacles or boundary surfaces. Additionally, the volume terms are rewritten to eliminate the need for the calculation of velocity gradients. A general purpose numerical implementation of this new formulation then produces a very attractive tool for engineering analysis. This implementation includes a Newton-Raphson algorithm, permitting accurate solutions up to the moderate Reynolds number range. Several numerical examples are provided to validate the present approach.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: International Journal for Numerical Methods in Engineering (ISSN 0029-5981); 31; 1627-164
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  • 8
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    A boundary element method for steady incompressible thermoviscous flow (1991)
    In:  Other Sources
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    Publication Date: 2019-07-12
    Description: A boundary element formulation is presented for moderate Reynolds number, steady, incompressible, thermoviscous flows. The governing integral equations are written exclusively in terms of velocities and temperatures, thus eliminating the need for the computation of any gradients. Furthermore, with the introduction of reference velocities and temperatures, volume modeling can often be confined to only a small portion of the problem domain, typically near obstacles or walls. The numerical implementation includes higher order elements, adaptive integration and multiregion capability. Both the integral formulation and implementation are discussed in detail. Several examples illustrate the high level of accuracy that is obtainable with the current method.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: International Journal for Numerical Methods in Engineering (ISSN 0029-5981); 31; 1605-162
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  • 9
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    Application of the boundary element method to transient heat conduction (1991)
    In:  Other Sources
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    Publication Date: 2019-07-12
    Description: An advanced boundary element method (BEM) is presented for the transient heat conduction analysis of engineering components. The numerical implementation necessarily includes higher-order conforming elements, self-adaptive integration and a multiregion capability. Planar, three-dimensional and axisymmetric analyses are all addressed with a consistent time-domain convolution approach, which completely eliminates the need for volume discretization for most practical analyses. The resulting general purpose algorithm establishes BEM as an attractive alternative to the more familiar finite difference and finite element methods for this class of problems. Several detailed numerical examples are included to emphasize the accuracy, stability and generality of the present BEM. Furthermore, a new efficient treatment is introduced for bodies with embedded holes. This development provides a powerful analytical tool for transient solutions of components, such as casting moulds and turbine blades, which are cumbersome to model when employing the conventional domain-based methods.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: International Journal for Numerical Methods in Engineering (ISSN 0029-5981); 31; 1231-124
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  • 10
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    Development of an integrated BEM approach for hot fluid structure interaction (1989)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The progress made toward the development of a boundary element formulation for the study of hot fluid-structure interaction in Earth-to-Orbit engine hot section components is reported. The convective viscous integral formulation was derived and implemented in the general purpose computer program GP-BEST. The new convective kernel functions, in turn, necessitated the development of refined integration techniques. As a result, however, since the physics of the problem is embedded in these kernels, boundary element solutions can now be obtained at very high Reynolds number. Flow around obstacles can be solved approximately with an efficient linearized boundary-only analysis or, more exactly, by including all of the nonlinearities present in the neighborhood of the obstacle. The other major accomplishment was the development of a comprehensive fluid-structure interaction capability within GP-BEST. This new facility is implemented in a completely general manner, so that quite arbitrary geometry, material properties and boundary conditions may be specified. Thus, a single analysis code (GP-BEST) can be used to run structures-only problems, fluids-only problems, or the combined fluid-structure problem. In all three cases, steady or transient conditions can be selected, with or without thermal effects. Nonlinear analyses can be solved via direct iteration or by employing a modified Newton-Raphson approach.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-186214 , NAS 1.26:186214
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