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  • 1
    Electronic Resource
    Electronic Resource
    Steady and nonsteady rates of reaction in a heterogeneously catalyzed reaction: Oxidation of CO on platinum, experiments and simulations (1989)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 91 (1989), S. 4949-4960 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The rate of reaction for oxidation of CO over (210) and (111) single-crystal surfaces of platinum has been studied as a function of reactant pressures (PO2,PCO) and sample temperature (T), both experimentally and by computer simulation. Experimental results on both surfaces show regions with a steady high rate of reaction followed by a nonsteady transition region and, at high CO pressures, a region with low reactivity caused by CO poisoning of the surface. At constant sample temperature, the transition region can be narrow and depends critically on the ratio of the gas phase concentration of reactants (PCO/PO2). The temperature dependences of the experimental data indicate that the critical ratio and the details for the occurrence of CO poisoning are strongly affected by surface processes such as adsorption, desorption, and diffusion ordering and reconstruction phenomena. A computer simulation model of the Langmuir–Hinshelwood surface reaction as developed by Ziff et al. was used for the simulation of the reaction under flow conditions. The initial fair agreement between this model and the experiment can be significantly improved if processes such as adsorption, desorption, and diffusion are taken into account in an extended simulation model which in turn provides an insight into the kinetics of adsorbate poisoning and the effect of adsorbate-induced processes on the reaction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.456736
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  • 2
    Electronic Resource
    Electronic Resource
    Raw materials testing using soft independent modeling of class analogy analysis of near-infrared reflectance spectra (1989)
    s.l. : American Chemical Society
    Analytical chemistry 61 (1989), S. 138-144 
    Details
    ISSN: 1520-6882
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ac00177a012
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  • 3
    Electronic Resource
    Electronic Resource
    Far-infrared and Raman spectra of gaseous 1,1,1-trifluoro-2-propanol: conformational stability and barriers to internal rotation (1987)
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 91 (1987), S. 3211-3218 
    Details
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/j100296a022
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  • 4
    Electronic Resource
    Electronic Resource
    A new boundary condition in the flow of rarefied gases at surfaces (1989)
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 1 (1989), S. 741-745 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A new boundary condition in the flow of rarefied gases at surfaces, based on the idea of completely diffuse scattering with respect to the local surface, is proposed. With the example of free-molecule-flow transmission probabilities in capillaries, results from the new boundary condition are compared with experimental data and with results, obtained here analytically, from the "backscattering'' model of Berman and Maegley [Phys. Fluids 15, 772, 780 (1972)]. The effective backscattering with the new boundary condition is related to the distribution of slopes of the local surface relative to the corresponding average geometrical surface. The analysis, in its present form, is restricted to the case of small local surface slopes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.857368
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  • 5
    Electronic Resource
    Electronic Resource
    Maximum sum-of-splits clustering (1989)
    Springer
    Journal of classification 6 (1989), S. 177-193 
    Details
    ISSN: 1432-1343
    Keywords: Partition ; Split ; Dendrogram ; Dual graph ; Complexity ; Polynomial algorithm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Description / Table of Contents: Résumé SoientN objets à classifier et une matrice de dissimilarit és entre paires de ces objets. L'écart d'une classe est la plus petite dissimilarité entre un objet de cette classe et un objet en dehors d'elle. L'algorithme du lien simple fournit des partitions enM classes dont le plus petit écart est maximum. On étudie l'écart moyen des classes, ou, ce qui est équivalent, la somme des écarts. On propose un algorithme en Θ(N 2) pour déterminer des partitions enM classes dont la somme des écarts est maximum pourM allant deN − 1 à 2, basé sur le graphe dual du dendrogramme de la méthode du lien simple.
    Notes: Abstract ConsiderN entities to be classified, and a matrix of dissimilarities between pairs of them. The split of a cluster is the smallest dissimilarity between an entity of this cluster and an entity outside it. The single-linkage algorithm provides partitions intoM clusters for which the smallest split is maximum. We study here the average split of the clusters or, equivalently, the sum of splits. A Θ(N 2) algorithm is provided to determine maximum sum-of-splits partitions intoM clusters for allM betweenN − 1 and 2, using the dual graph of the single-linkage dendrogram.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01908598
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  • 6
    Electronic Resource
    Electronic Resource
    Determination of various deformation processes in impact-modified PMMA at strain rates up to 105%/min (1986)
    Springer
    Colloid & polymer science 264 (1986), S. 473-481 
    Details
    ISSN: 1435-1536
    Keywords: Polymethyl methacrylate ; tensile deformation ; volume change ; deformation processes ; impact strength
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The deformation processes in impact-modified PMMA, which deforms homogeneously, were determined by means of the stress/strain experiment (α, ɛ) with simultaneous lateral strain measurement (εlat) in a wide range of strain rates (ɛ) up to 105%/min (impact stress). The elastic, plastic cavitation and plastic shear processes were determined as a function of strain. Therefore we calculated the elastic strain (ɛ el), the elastic volume expansion (ɛ vol el), the cavitation strain (ɛ cav), which is identical with the plastic volume expansion (ɛ vol pl), the shear strain (ɛ sh) and the energy densities (Wel, Wcav, Wsh) related to these three processes. For strains of 3 % onward it was found that plastic shear processes and plastic cavitation processes are responsible for a partial loss of elastically stored energy. Both plastic processes turn out to be mostly anelastic deformations, their amount depending strongly on the strain rate. The contributions of the processes to the total deformation of the unmodified PMMA in its strain range are similar to those of the impact-modified PMMA, and the high impact strength is caused by a shift of the catastrophic rupture to very high strains.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01421999
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  • 7
    Electronic Resource
    Electronic Resource
    Polyamide 6,6 fibers: Tensile deformation behavior and chain scission (1988)
    Springer
    Colloid & polymer science 266 (1988), S. 216-226 
    Details
    ISSN: 1435-1536
    Keywords: Tensile deformation ; chain rupture ; ESR spectroscopy ; polyamide 6,6fibers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The strain dependence of the elastic, anelastic and plastic components of deformation energy was determined by means of cyclic stress-strain experiments for a set of polyamide 6,6 fibers obtained by different processing techniques. Small angle X-ray scattering experiments revealed that the deformation of the supermolecular lattices of the fibers, consisting of crystalline lamellae and amorphous regions, was identical to the macroscopic deformation of the sample. ESR experiments showed that deformation gives rise to chain rupture events obviously occurring in the amorphous regions in all fibers above a critical strain level. The strain dependence of the free radical concentration was found to agree closely with the corresponding behavior of the plastic deformation energy. This indicates that chain rupture events influence stress-strain properties, particularly at large strains. The absolute values of the experimentally determined plastic deformation energy and of the theoretical value, however, calculated from the number and energy balance of ruptured chains, disagree strongly. Possible explanations are free radical recombinations and secondary dissipative processes resulting from chain rupture.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01452583
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  • 8
    Electronic Resource
    Electronic Resource
    Vitamins and other metabolites in various sera commonly used for cell culturing (1988)
    Springer
    Cellular and molecular life sciences 44 (1988), S. 1007-1010 
    Details
    ISSN: 1420-9071
    Keywords: Vitamins ; cell culture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Many cell culture media use different sera to enhance growth. We assayed vitamins and some related metabolites in different sera and identified the concentration of: thiamin, biotin, folates, riboflavin, pantothenates, nicotinates, vitamins B6, B12, A, E. C, and carotenes and some related metabolites: biopterins, free inositol, free and total choline, total carnitines in chicken, horse, rabbit, goat, pig, calf, newborn calf, fetal calf and human sera. Results indicate that vitamin and metabolite concent of different sera vary. Such variations could produce fluctuant effects on cell culturings if the metabolite content of the serum is not documented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01939904
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  • 9
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    Far-infrared and Raman spectra of gaseous 1,1,1-trifluoro-2-propanol: conformational stability and barriers to internal rotation (1987)
    American Chemical Society
    Details
    Publication Date: 1987-06-01
    Print ISSN: 0022-3654
    Electronic ISSN: 1541-5740
    Topics: Chemistry and Pharmacology , Physics
    Published by American Chemical Society
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  • 10
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    Vitamins and other metabolites in various sera commonly used for cell culturing (1988)
    Springer
    Details
    Publication Date: 1988-12-01
    Print ISSN: 0014-4754
    Topics: Biology , Medicine
    Published by Springer
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