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  • Wiley-Blackwell  (16)
  • 2015-2019
  • 1995-1999
  • 1985-1989  (16)
  • 1988  (16)
  • 1
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988), S. 1825-1841 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A ‘multiple determinant parabolic interpolation method’ is described and evaluated, principally by using a plane frame test-bed program. It is intended primarily for solving the transcendental eigenvalue problems arising when the ‘exact’ member equations obtained by solving the governing differential equations of members are used to find the eigenvalues (i.e. critical buckling loads or undamped natural frequencies) of structures. The method has five stages which together ensure successful convergence on the required eigenvalues in all circumstances. Thus, whenever checks indicate its suitability, parabolic interpolation is used to obtain eigenvalues more rapidly than would the popular bisection alternative. The checks also ensure a wise choice of the determinant used by the interpolation. The determinants available are all usually zero at eigenvalues, and comprise the determinant of the overall stiffness matrix Kn and the determinants which result, with negligible extra computation, from effectively considering all except the last m (m=1, 2,…, n-1) freedoms to which Kn corresponds as internal substructure freedoms. Tests showed time savings compared to bisection of 31 per cent when finding non-coincident eigenvalues to relative accuracy ∊ = 10-4, increasing to 62 per cent when ∊ = 10-8. The tests also showed time savings of about 10 per cent compared with an earlier Newtonian approach. The method requires no derivatives and its use in the widely available space frame program BUNVIS-RG has demonstrated how easily it can replace bisection, which was used in the earlier program BUNVIS.
    Additional Material: 9 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Materialwissenschaft und Werkstofftechnik 19 (1988), S. 1-14 
    ISSN: 0933-5137
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: In Früheren Veröffentlichungen [1,2] wurde bereits eingehend über die Arbeit auf dem Gebiet der Oberflächentechnik berichtet. Nun gilt es, den derzeitigen Stand darzustellen. Dabei sind fünf Schwerpunkte zu nennen: die Galvanotechnik, die Kavitations-Korrosion, die Spannungsrißkorrosion, die Untersuchung von Korrosionsvorgängen bei höheren Temperaturen und Drücken, die Schwingungsrißkorrosion.In jedem dieser Bereiche erfolgt stets eine enge Zusammenarbeit mit der Industrie, sei es z.B. mit Fachfirmen für Galvanotechnik und mit Lohngalvanisierbetrieben, mit Herstellern von Strömungsmaschinen, mit Herstellern und Betreibern von Verbrennungskraftmaschinen, mit der chemischen Industrie und der Mineralölindustrie, mit Stahlwerken sowie auch mit technischen Vereinigungen wie der Gütegemeinschaft Galvanotechnik e.V.Oftmals erfolgen die Anregungen zur Formulierung und Durchführung von Forschungsvorhaben unmittelbar aus der Klärung von Schadensfällen. Untersuchungen aus diesem Problemkreis sind beispielsweise in [3] beschrieben, aber auch in [4] und [5].Nachfolgend stellen die wissenschaftlichen Mitarbeiter in der Abteilung Oberflächentechnik Teilgebiete aus ihren derzeitigen Forschungsarbeiten vor. Dabei ist hervorzuheben, daß dies Ausschnitte sind aus langjährigen Untersuchungen, basierend unter anderem auf vorausgegangenen Dissertationen [6-9] und weiteren wissenschaftlichen Publikationen. So wird eine Kontinuität in der Erforschung des Werkstoffverhaltens bei elektrochemischer und kombinierter mechanisch-elektrochemischer Beanspruchung hergestellt, wobei ständig neue, verfeinerte Untersuchungs-, Meß- und Prüfmethoden Anwendung finden, die zu einem tieferen Verständnis der im einzelnen ablaufenden Schädigungsmechanismen führen und damit die Grundlagen zur Erarbeitung von Maßnahmen zur künftigen Vermeidung oder doch wenigstens Minimierung von Schäden in der Praxis liefern. Dies ist von wesentlicher Bedeutung hinsichtlich der Werkstoffauswahl, der Werkstoffausnutzung, der Betriebssicherheit, der Gebrauchsdauer und der Verfügbarkeit technischer Geräte und Anlagen.
    Additional Material: 41 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 11 (1988), S. 313-317 
    ISSN: 0935-6304
    Keywords: Capillary gas chromatography ; Major metabolites ; Minor metabolites ; Human urine ; Aromatic solvents ; Biological monitoring ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Aromatic solvents are involved in manifold areas of industry and craft. Inhaled solvent vapors are a known health hazard to workers. For medical prevention and toxicological assay specific laboratory methods for urinary metabolites are necessary. An economical capillary gas chromatographic procedure is described which is suitable for routine analysis of major metabolites, sensitive for the determination of minor metabolites, and effective for the separation of chiral metabolic intermediates.
    Additional Material: 5 Ill.
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  • 4
    ISSN: 0148-7280
    Keywords: acrosome reaction ; fertilization ; lipoproteins ; lipids ; albumin ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The nature of cholesterol-binding proteins acting upon human spermatozoa during in vitro capacitation was determined by measuring the efflux of [3H]cholesterol and of [3H]cholesteryl sulfate from labeled spermatozoa. Efflux of [3H]sterols was stimulated when the labeled gametes were incubated in Ham's F-10 medium supplemented with female serum or follicular fluid. Upon centrifugation of capacitated spermatozoa and application of the supernatant to density-gradient ultracentrifugation for lipoprotein analysis, both [3H]cholesterol and [3H]cholesteryl sulfate were found to be carried by very-low-density lipoproteins (VLDL), low-density lipoproteins (VLDL), high-density lipoproteins (HDL), as well as the albumin fraction (d 〉 1.21) in serum. When the capacitation medium was supplemented with follicular fluid, the [3H]sterols were bound to HDL's and to the albumin fraction; when the latter fraction was analysed by molecular sieve chromatography, 60-70% of the radioactivity eluted in fractions with a mean molecular weight corresponding to that of human serum albumin. Sperm cholesterol efflux was also stimulated when serum or follicular fluid was added to a simplified medium (50 mM Tris-HCl, 0.56% NaCl, pH 7.8); efflux of [3H]cholesterol from labeled gametes progressed in a time-dependent manner, but was low in the absence of serum components. The [3H]cholesterol/cholesterol ratios were higher in the albumin and HDL fractions, indicating some degree of specificity of these sterol acceptors. It was observed that follicular fluid albumin has a [3H]sterol binding capacity that is 2 - 3-fold higher than that of serum albumin. Commercial human serum albumin also promoted sperm cholesterol efflux. These results provide new information concerning those components of follicular fluid which may play a role in human sperm capacitation and provide further support for the concept that loss of cholesterol from the sperm plasma membrane is an important component of the capacitation process.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    X-Ray Spectrometry 17 (1988), S. 23-27 
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Relative experimental detector yields and yield ratios measured on mono- and bi-element standard samples from 1984 to 1987 are presented. Above 3 keV photon energy the yields show good long-term reproducibility. For example, the spread of 38 single yield measurements on the Au Lα x-ray line is 1.5%. No temporary changes are observed. In contrast, the measured yields in the photon energy range from 3 keV down to 0.9 keV show distinct temporary changes. At the beginning and end of the measurement period the detector was routinely warmed and re-pumped in order to ensure a good vacuum in the detector housing. At these times the yields show jumps, which increase with decreasing photon energy up to 20% for Na K x-rays with 1.041 keV photon energy. Between the detector regenerations the yields show a decreasing tendency with time. This behaviour is attributed to the photon absorption in a varying ice layer on the liquid nitrogen-cooled Si(Li) detector crystal. After the first regeneration the ice layer thickness was reduced by 0.7 μm. Between the regenerations the ice layer growth rate is estimated to be 0.004 μm per month corresponding to a 0.15 μm ice layer after 35 months. The second regeneration reduced the ice layer by a further 0.22 μm.
    Additional Material: 3 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    BioEssays 8 (1988), S. 130-132 
    ISSN: 0265-9247
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Recent theoretical and experimental studies are in conflict with our previous neutralization-reionization evidence for the surprising stability of simple ylides such as H2CCIH. Neutralization of [H2CCIH]+· ions from CICH2COOH with Hg followed by reionization of the resulting neutral molecules with O2 produces intense [CCIH3]+· parent ions. Collisionally activated dissociation of these mass-selected ions shows that 47 ± 5% are the [H2CCIH]+· isomer. This demonstrates that stable H2CCIH molecules can be formed by neutralization, surviving intact for the lifetime of the experiment (10-6 s). Field ionization conditions effective in ionizing excited argon atoms do not produce appreciable ionization of the neutrals from [H2CCIH]+·, suggesting that the stable H2CCIH neutrals are not Rydberg state molecules.
    Additional Material: 3 Ill.
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  • 8
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A cyclic peptide analogue of somatostatin, including the o-aminomethylphenylacetic acid spacer, was studied by the combined use of two-dimensional nmr spectroscopy, distance geometry, and restrained molecular dynamics. Analysis of distances determined from nuclear Overhauser effect (NOE) buildup rates revealed that these were inconsistent with a unique backbone conformation near the spacer. Assuming that the conformational heterogeneity is localized to the spacer, the NOE distances measured for the remaining part of the molecule were used to generate a large number of structures with the distance geometry algorithm, which were then refined by restrained energy minimization. Four classes of structures emerged, which together account for all observed NOEs. A representative structure of each class was further refined with the restrained molecular dynamics technique, and shown to be stable on a 20-ps time scale. The flexibility of the spacer was examined by simulating interconversions induced by an appropriate restraining potential. As a result, the explanation for the lack of somatostatin activity of the analogue studied was reconsidered.
    Additional Material: 5 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 35 (1988), S. 787-796 
    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 Young's moduli of samples of poly(vinyl chloride) containing either no plasticizer or 5 pph of dioctyl sebacate were drawn uniaxially at 80°C to draw ratios, λ, in the range 1-3.3. The moduli, determined by a three-point bending method were found to increase monotonically with λ to a value of 6.3 GPa for the nonplasticized samples and to reach a maximum value of about 4.5 GPa for the plasticized samples above λ = 2.3, which showed voiding. The lower moduli of the plasticized samples for a given degree of orientation, as assessed from birefringence measurements, can be attributed to the diluent effect of the plasticizer on the load-bearing chains. The Raman measurements suggest that the crystallites probably orient rather like rigid rods in an affinely deforming matrix, with some relaxation.
    Additional Material: 6 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 31 (1988), S. 567-578 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In production-scale bioreactors microorganisms are exposed to a continually changing environment. This may cause loss of viability, reduction of the yield of biomass or desired metabolites, and an increase in the formation of by-products. In fed-batch production of baker's yeast, profiles may occur in substrate and oxygen concentrations and in pH. This article deals with the influence of a periodically changing oxygen concentration on the growth of baker's yeast in a continuous culture. Also, influences on the production of ethanol, glycerol, acetic acid, and on the composition of the cells were investigated. It was found that relatively fast fluctuations between oxygen-unlimited and oxygen-limited conditions with a frequency of 1 or 2 min had a distinct influence on the biomass and metabolite production. However, RNA, protein, and carbohydrate contents measured in cells exposed to fluctuations differed little from those in cells from an oxygen-unlimited or an oxygen-limited culture. The respiration and fermentation capacities of cells exposed to fluctuations can be larger than the capacities of cells grown under oxygen-unlimited conditions.
    Additional Material: 8 Ill.
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