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  • 1
    Electronic Resource
    Electronic Resource
    Heterogeneous nucleation and growth of spherulites from a polycaprolactone (poly(1-oxy-6-oxohexamethylene)) melt (1974)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 175 (1974), S. 2483-2488 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Es wird über den Beginn einer Untersuchung zur Kristallisationskinetik von Polycaprolacton (Poly(1-oxy-6-oxohexamethylene) (1)) berichtet. Die primäre Keimbildung und das primäre Sphärolith-Wachstum aus der Polymerschmelze werden bei hinreichend hohen Temperaturen verfolgt, wodurch sichergestellt ist, daß das Wachstum der Kristallite durch Keimbildung bestimmt ist. Die kinetischen Daten werden weitgehend mit Hilfe des Avrami-Modells interpretiert, welches sich gut auf die Kristallisation von 1 anwenden ließ.
    Notes: A kinetic crystallization study of polycaprolactone (poly(1-oxy-6-oxohexamethylene) (1)) has been initiated to investigate the primary nucleation and primary spherulitic growth from a polymer melt at temperatures that are high enough to insure nucleation-limited crystallite growth. The analysis of the kinetic data is largely made on the basis of an Avrami model which proved to be well suited for the interpretation of the crystallization of 1.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1974.021750821
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  • 2
    Electronic Resource
    Electronic Resource
    Osteoblast migration on poly(α-hydroxy esters) (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 50 (1996), S. 443-451 
    Details
    ISSN: 0006-3592
    Keywords: osteoblast ; migration ; poly(αhydroxy esters) ; poly(DL-lactic-co-glycolic acid) ; PLGA ; biodegradable polymers ; tissue engineering ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: We investigated the migration of rat calvaria osteoblast populations on poly(α-hydroxy ester) films for up to 14 days to determine effects of substrate composition and culture conditions on the migratory characteristics of osteoblasts. Initial osteoblast culture conditions included cell colonies formed by seeding a high (84,000 cells/cm2) or low (42,000 cells/cm2) density of isolated osteoblasts on the polymer films, and bone tissue cultures formed by plating bone chips directly on the substrates. High density osteoblast colonies cultured and allowed to migrate and proliferate radially on 85:15 poly(DL-lactic-co-glycolic acid) (PLGA) films, 75:25 PLGA films, and tissue culture polystyrene controls demonstrated that the copolymer ratio in the polymer films did not affect the rate of increase in substrate surface area (or culture area) covered by the growing cell colony. However, the rate of increase in culture area was dependent on the initial osteoblast seeding density. Initial cell colonies formed with a lower osteoblast seeding density on 75:25 PLGA resulted in a lower rate of increase in culture area, specifically 4.9 ± 0.3 mm2/day, versus 14.1 ± 0.7 mm2/day for colonies seeded with a higher density of cells on the same polymer films. The proliferation rate for osteoblasts in the high and low density seeded osteoblast colonies did not differ, whereas the proliferation rate for the osteoblasts arising from the bone chips was lower than either of these isolated cell colonies. Confocal and light microscopy revealed that the osteoblast migration occurred as a monolayer of individual osteoblasts and not a calcified tissue front. These results demonstrated that cell seeding conditions strongly affect the rates of osteoblast migration and proliferation on biodegradable poly(α-hydroxy esters). © 1996 John Wiley & Sons, Inc.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Adaptive, global, extended Kalman filters for training feedforward neural networks (1994)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 8 (1994), S. 391-407 
    Details
    ISSN: 0886-9383
    Keywords: Neural networks ; Non-linear multivariate regression ; Pattern classification ; Kalman filter ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Finding methods for the optimization of weights in feedforward neural networks has become an ongoing developmental process in connectionist research. The current focus on finding new methods for the optimization of weights is mostly the result of the slow and unreliable convergence properties of the gradient descent optimization used in the original back-propagation algorithm. More accurate and computationally expensive second-order gradient methods have displaced earlier first-order gradient optimization of the network connection weights. The global, extended Kalman filter is among the most accurate and computationally expensive of these second-order weight optimization methods. The iterative, second-order nature of the filter results in a large number of calculations for each sweep of the training set. This can increase the training time dramatically when training is conducted with data sets that contain large numbers of training patterns. In this paper an adaptive variant of the global, extended Kalman filter that exhibits substantially improved convergence properties is presented and discussed. The adaptive mechanism permits more rapid convergence of network training by identifying data that contain redundant information and avoiding calculations based on this redundant information.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cem.1180080605
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  • 4
    Electronic Resource
    Electronic Resource
    Dynamic analysis of a microbial process: A systems engineering approach (1973)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 15 (1973), S. 377-393 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A general mathematical model of the chemostat system is developed in order to define an experimental program of dynamic testing. A glucose-limited culture ofSaccharomyces cerevisiae was grown in a chemostat using chemically defined medium. The chemostat was perturbed from an initial steady state by changes in input glucose concentration, dilution rate, pH, and temperature. Dynamic responses of cell mass, glucose, cell number, RNA, and protein concentrations were measured. A number of simulation techniques were used in developing a dynamic mathematical model and in comparing the developed model with experimental data as well as the Monod model. The resulting model was found to be quantitatively accurate and superior to the Monod model. The developed model was interpreted in the light of cell physiology. Adjustment of intracellular RNA fraction was found to be rate limiting in acceleration of cell specific growth rate.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260150212
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  • 5
    Electronic Resource
    Electronic Resource
    Perimeter Exploration of Linear Chains of Circles (1995)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 12 (1995), S. 257-263 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Perimeter data, obtained from structured walks performed upon straight chains of circles and displayed in Richardson plots, reveal two distinct classes of discontinuities: textural and structural. Textural discontinuities contain information about the surface features of the profile, while structural discontinuities reveal the profile's overall shape. The origins of both types of discontinuities have easy explanations. The highly predictable behavior of the structural discontinuities serves as the basis of a newly proposed method of analysis for perimeter data. The number of structural discontinuities is equal to N, the number of circles in the chain; furthermore, the value of the step size \documentclass{article}\pagestyle{empty}\begin{document}$ \underline {\lambda} $\end{document} * associated with the first structural discontinuity is inversely related to N. These properties seem is be retained when the circles slightly intersect and also when the circles vary in diameter. Analysis of the structural discontinuities may provide a new method suitable for automated examination of chain-like agglomerate particles.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19950120508
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  • 6
    Electronic Resource
    Electronic Resource
    Bacteriorhodopsin α-helices in lipid settings: Insights for structure prediction (1998)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 69 (1998), S. 105-116 
    Details
    ISSN: 0020-7608
    Keywords: bacteriorhodopsin ; protein: lipid interactions ; α-helices ; molecular dynamics ; membrane protein tertiary structure prediction ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The two-stage model of membrane protein folding predicts that isolated transmembrane α-helices form stably in the bilayer before coming together to form the fully functional protein. Insight into the molecular implications of this model are possible with detailed molecular dynamics calculations. Thirty molecular dynamics simulations of both individual and pairs of α-helices from bacteriorhodopsin were calculated with the CHARMm program. This data base will continue to grow and expand. Already, differences between identical helices in different media and different helices in the same media have been found. The current results are summarized in this contribution.   © 1998 John Wiley & Sons, Inc. Int J Quant Chem 69: 105-116, 1998
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    A new technique for preparing monodisperse polymer particles (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 45 (1992), S. 1783-1788 
    Details
    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: A procedure is described for preparing fairly uniform spheres of three different nylon polymers by phase separation. The mean diameter and polydisperse index were 5 μm and 1.056 for Griltex nylon, 5.7 μm and 1.046 for nylon 6/6, and 12.9 μm and 1.016 for nylon 6. The phase separation is done by taking a 1 wt % solution in a theta solvent above the theta temperature and cooling it rapidly. The spheres of the three nylons have various degrees of roughness. Formation of highly uniform particles during phase separation is discussed in a preliminary way. © 1992 John Wiley & Sons, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1992.070451012
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  • 8
    Electronic Resource
    Electronic Resource
    A new approach to chemical characterization of polymer surfaces (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 58 (1995), S. 291-296 
    Details
    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 “three-liquid” contact angle procedure of Good et al. was applied to polymer films of varying Lewis acidic and basic nature to test the procedure. Surface energy parameters with the units of mJ/m2 are determined for the surfaces. These are γLWs (Lifshitz-van der Waals or apolar), γ+s (acidic), and γ-s (basic). Very little has yet been published on this new method, and this study found it to be promising. More research on the procedure is warranted. The study included films of basic polymethylmethacrylate (PMMA), and predominately acidic chlorinated polyvinylchloride (CPVC) and polyvinylfluoride (PVF) as well as the series: polyethylene (PE) and PE copolymerized with 1.8% and 7.0% acrylic acid. In some of the experiments receding contact angles were measured, and the surface energy parameters determined in order to cast more light on the mechanism of contact angle hysteresis. © 1995 John Wiley & Sons, Inc.
    Additional Material: 6 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1995.070580208
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  • 9
    Electronic Resource
    Electronic Resource
    Produktzusammensetzung der Kohlenwasserstoffgemische nach der BIRCH-Reduktion substituierter Benzene und säurekatalysierte Addition von Alkoholen an alkylsubstituierte Cyclohexene und Cyclohexa-1,4-diene (1991)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 333 (1991), S. 481-488 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Composition of Mixtures of Hydrocarbons after BIRCH-Reduction of Substituted Benzenes and Acid Catalyzed Addition of Alcohols to Alkylsubstituted Cyclohexenes and Cyclohexa-1,4-dienes.10 different benzene hydrocarbons 1, indane, tetraline, anisol and phenol are reduced by sodium in liquid ammonia in the presence of methanol to the BIRCH products 2. The product mixture compositions are determined through capillary GLC. On storage at + 6°C some rearomatization of the 1,4-cyclohexadienes 2 occurs. Data of the 1H- and 13C-n.m.r. spectra and also mass spectra of the BIRCH 1,4-dienes 2 are given. For comparison 4-alkoxycyclohexenes 4 and 1-alkoxy-1-methylcyclohexanes 8 are prepared and spectroscopically characterized. Acid-catalyzed addition of alcohols to the 1,4-cyclohexadiene systems is a slow process and gives the 4-alkoxy-4-alkylcyclohex-1-enes (4) only in moderate yields up to 30 %. Most of the products are dimers 5 and also oligomers 6 of the parent hydrocarbons 2.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19913330315
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  • 10
    Electronic Resource
    Electronic Resource
    Dreikomponentenreaktionen. XX. Methoxymercurierung von Cyclohexa-1,4-dienen (1991)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 333 (1991), S. 447-453 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Three Component Reactions. XX. Methoxymercuration of Cyclohexa-1,4-dienes.The methoxymercuration of several cyclohexa-1,4-dienes leads to insoluble mixtures of mono- and bismercuricompounds 2-4 and 5-7. After reduction with NaBH4/NaOH mixtures of methoxycyclohexenes and bismethoxycyclohexanes result. The result of capillary gaschromatographic analyses and n.m.r. spectra allow a semiquantitative evaluation of the reaction pathways.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19913330310
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