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  • 1
    Electronic Resource
    Electronic Resource
    Expanded and packed bed albumin adsorption on fluoride modified zirconia (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 60 (1998), S. 333-340 
    Details
    ISSN: 0006-3592
    Keywords: fluoride-modified zirconia ; expanded bed ; packed bed ; protein adsorption ; adsorption-desorption kinetics ; intraparticle diffusion ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The expanded bed characteristics of 75-103μm fluoride-modified zirconia (FmZr) particles synthesized by a fed batch oil emulsion process were investigated. These particles are distinguished from commercially available expanded-bed adsorbents by virtue of their high density (2.8 g/cc) and the mixed mode protein retention mechanism which allows for the retention of both cationic and anionic proteins. The linear velocity versus bed porosity data agree with the Richardson-Zaki relationship with the terminal velocity in infinite medium of 2858.4 cm/h and a bed expansion index of 5.1. Residence time distribution (RTD) studies and bovine serum albumin (BSA) adsorption studies were performed as a function of the height of the settled bed to the column diameter (H:D) ratio and degree of bed expansion with superficial velocities of 440 to 870 cm/h. The settled bed, a 2× expanded bed, and a 3× expanded bed were studied for the H:D ratios of 1:1, 2:1, and 3:1. The dynamic binding capacity (DBC) at 5% breakthrough was low (2-8 mg BSA/mL settled bed) and was independent of the H:D ratio or the degree of bed expansion. The saturation DBC was 32.3 ± 7.0 mg BSA/mL settled bed. The adsorption-desorption kinetics and intraparticle diffusion for protein adsorption on FmZr (38-75 μm) were investigated by studying the packed bed RTD and BSA adsorption as a function of temperature and flow rate. The data show that the adsorption-desorption kinetics along with intraparticle diffusion significantly influence protein adsorption on FmZr. Low residence times (∼0.8 min) of BSA result in a DBC at 5% breakthrough which is 3.5-fold lower compared to that at 6-fold higher protein residence time. At low linear velocity (45 cm/h) the breakthrough curve is nearly symmetrical and becomes asymmetrical and more dispersed at higher linear velocity (270 cm/h) due to the influence of slow adsorption-desorption kinetics and intraparticle diffusion.© 1998 John Wiley & Sons, Inc. Bioeng 60: 333-340, 1998.
    Additional Material: 4 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    Motility behavior of hepatocytes on extracellular matrix substrata during aggregation (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 50 (1996), S. 392-403 
    Details
    ISSN: 0006-3592
    Keywords: cell migration ; hepatocytes ; cell-substrata adhesion ; Matrigel ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Aggregation of hepatocytes in culture is an important phenomenon to control in tissue engineering applications. Aggregation generally enhances maintenance of differentiated functions but inhibits cell growth. At present there exists insufficient information for rational design of substrata that control aggregation. Indeed, the cellular mechanism(s) underlying the aggregation process is poorly understood, although cell motility is generally considered to be an essential phenomenon. In this article we provide the first study investigating the relationship between hepatocyte aggregation and motility behavior on various extracellular matrix substrata, including Matrigel, laminin, and fibronectin. We find that the extent of aggregation depends on the concentration of the extracellular matrix proteins, as well as on the type. Furthermore, we find that the extent of aggregation appears to be independent of classical single-cell locomotion. In fact, under conditions giving rise to substantial aggregation, the fraction of cells exhibiting classical locomotion is essentially negligible. Instead, aggregation appears to involve intracellular contacts accomplished via a different form of cell motility: active cell membrane extensions followed by adhesive cell-cell interactions. An implication of these findings is that aggregation may be largely governed by relative strengths of cell-cell versus cell-substratum interactions. These observations could be helpful for improved design of cell transplantation devices and cell culture substrata. © 1996 by John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    Cell-substratum adhesion strength as a determinant of hepatocyte aggregate morphology (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 53 (1997), S. 415-426 
    Details
    ISSN: 0006-3592
    Keywords: hepatocytes ; cell adhesion ; spheroids ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Cultured hepatocytes typically form multicellular aggregates which are either monolayered or spheroidal in morphology. We propose that the aggregate morphology resulting from a particular cell-substratum interaction has a biophysical basis: when cell contractile forces are greater than cell-substratum adhesion forces, spheroidal aggregates form; when cell contractile forces are weaker than cell-substratum adhesion forces, cells remain essentially spread and form monolayered aggregates. We tested this hypothesis by systematically varying the morphology of hepatocellular aggregates formed on substrata coated with a series of different concentrations of Matrigel, and correlating aggregate morphology with the cell-substratum adhesion strength measured in a shear flow detachment assay. Aggregate morphology was binary - spheroidal aggregates formed at low Matrigel concentrations and monolayered aggregates formed at high Matrigel concentrations. Cell-substratum adhesion strength was similarly binary, with low adhesion strengths correlated with spheroidal aggregates and high adhesion strengths correlated with formation of monolayered aggregates. © 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 53: 415-426, 1997.
    Additional Material: 6 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    Crystallization kinetics of isotactic polypropylenePresented at the Spring Meeting of the American Chemical Society, Boston, Massachusetts, April 7, 1959. (1959)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 38 (1959), S. 107-116 
    Details
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Crystallization kinetics of Hercules polypropylenes were studied between 133 and 155°C. using dilatometers. The crystallization rates of these samples became too rapid below 133°C. for accurate dilatometric measurements. One sample (A) was a commercial sample containing stabilizer and 9% extractable polymer (with boiling n-heptane). B was an experimental extracted sample containing no stabilizer. A portion of B was thermally degraded under vacuum at 350°C. for 7 hr. (C). The DPn′s of A, B, and C were 2300, 7300, and 1200, respectively. Their melting points were determined dilatometrically, under conditions approaching equilibrium, and were 175, 176, and 173°C., respectively. 95% of the crystallization can be described by an Avramitype equation with an n value of 3, indicating a three-dimensional growth with residual nucleation or a two-dimensional growth with spontaneous nucleation. The heterogeneities may result from catalyst residues. The crystallization rate of A was lower than that of B or C at a given temperature, possibly due to the presence of atactic polymer. At a given temperature C crystallized faster than B, which may be an effect of the difference in molecular weight. Plotting the rate as a function of the degree of undercooling (ΔT) increases the difference between B and C.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1959.1203813310
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  • 5
    Electronic Resource
    Electronic Resource
    Dilatometric measurements on poly(4-methyl-1-pentene) glass and melt transition temperatures, crystallization rates, and unusual density behavior (1960)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 44 (1960), S. 369-381 
    Details
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Dilatometers were used to measure the volume-temperature curves of seven poly(4-methyl-1-pentene) (PMP) samples between -30 and +270°C., and to measure crystallization rates on one sample between 220 and 236°C. A glass transition temperature of 18-29°C. was found, and the crystalline melting point was found to be 250°C. The value of dV/dT above and below the glass temperature was used to measure the degree of crystallinity. The results indicate that the crystalline PMP is less dense at room temperature than the amorphous polymer. However, because of different rates of expansion, the normal positive volume change on melting is observed. A density value of 0.828 ± 0.002 g./ml. at 20°C. is calculated for the PMP crystal.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1960.1204414408
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  • 6
    Electronic Resource
    Electronic Resource
    Molecular mechanics study of transannular amine-ketone (N→C(DOUBLE BOND)O) interaction in medium-sized heterocycles (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 18 (1997), S. 1211-1221 
    Details
    ISSN: 0192-8651
    Keywords: force fields ; medium-sized heterocycles ; transannular interaction ; drug design ; molecular modeling ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Medium-sized nitrogen-containing heterocycles have considerable potential as structurally novel templates for new medicinal agents. In order to evaluate this potential and to investigate their binding to various target receptors, satisfactory modeling of the properties of such compounds with force-field based computational methods is required, especially the conformations accessible to the molecules at and around their global minimum conformation. This is currently only possible with selected force fields for compounds that show a special intramolecular interaction such as the transannular interaction between a basic nitrogen atom and a carbonyl carbon atom. This article substantiates this claim and discusses two approaches to modify the commercially available CFF91 force field. The different approaches are discussed and assessed by their performance in reproducing the conformation in the crystal for a series of known model compounds. In summary, very good agreement with the experimental structure is achieved. The modified force fields are then used to investigate a potentially bioactive lead compound. The lead compound is predicted to be able to mimic the shape of a fused-ring compound with biological activity. © 1997 John Wiley & Sons, Inc.   J Comput Chem 18: 1211-1221
    Additional Material: 2 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    Micellar effects on the rate and the polymer molecular weight in acrylamide polymerization catalyzed by bisulfite (1975)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Letters Edition 13 (1975), S. 525-531 
    Details
    ISSN: 0360-6384
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1975.130130904
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  • 8
    Electronic Resource
    Electronic Resource
    The rheology and mold flow of polyester sheet molding compoundPortions of this work have been presented at the 2nd World Congress Chemical Engineering. Montreal. Canada, October 1981. (1981)
    Brookfield, Conn. : Wiley-Blackwell
    Polymer Composites 2 (1981), S. 209-218 
    Details
    ISSN: 0272-8397
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Flow properties of sheet molding compounds (SMC) were measured by several rhemeters. Shear viscosities of SMC paste can be fitted by the Carreau viscosity equation and reduced to a single master curve by plotting the reduced shear viscosity (η/η0) against reduced shear rate (\documentclass{article}\pagestyle{empty}\begin{document}$ \dot \gamma $\end{document} η0/T). The deformation fo glass filled compounds under extensional forces. When the shear forced was applied, the compound defomed like a deck of cards being slid. It behaved essentially like a laminate of many layers. On the other hand, SMC compounds elongated much less before sample failure occurred under the extensional flow. The extensional viscosity was much higher than the shear viscosity. This phenomenon was explained by a solid composite theory and theories developed from local shear flows between adjacent fibers. The flow of SMC compounds during molding showed that the surface layers flowed further than the inner layers when the mold surfaces were hot. This casued inner plies to show through at the surface and resulting in some wavy glass orientation. This phenomenon was explained equalitatively by a heat penetration model.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pc.750020412
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  • 9
    Electronic Resource
    Electronic Resource
    Determination of pendant allyl and monomer content in polydiallylphthalate (1984)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 29 (1984), S. 407-411 
    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: Methods are described for the determination of diallylphthalate monomer and pendant allyl contents in homopolymers of diallylphthalate. The monomer content was determined by gel permeation chromatography. The total allyl content was determined by FTIR and computer subtraction of solvent spectrum. The pendent allyl content can be calculated from the difference between total allyl and allyl caused by monomer. Determination of both monomer and pendant allyl content in the prepolymer is essential for accurate prediction of the physical properties of the cured polymer.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1984.070290138
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  • 10
    Electronic Resource
    Electronic Resource
    Electrically conducting polymers from conjugated bis-phthalonitrile monomers (1985)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 30 (1985), S. 2921-2939 
    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: Elelectrically conducting polymers have been synthesized from completely conjugated bisphthalonitrile monomers. The monomers melt and are thermally polymerized at 260-300°C in air and then are converted into conductive materials by further processing at elevated temperatures in an inert atmosphere. Because the monomers remain in a liquid stage for 1-2 h, depending on the cure conditions, moldings, castings, and pre-pregs can be fabricated using conventional processing techniques. The conductivity can be varied from that of an insulator to approximately 10+2(Ωh cm)-1. For example, after a 600°C treatment, the conductivity is approximately 1(Ω cm)-1. Since reactive dopants are not used, the material and conductivity are stable in ambient as well as more aggressive environments, allowing them to function at 300°C and above. The monomers are well characterized, but the structure of the cured and postcured polymers are not yet well defined because of their high stability and intractability in the cured state.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1985.070300717
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