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  • Articles  (4,412)
  • Polymer and Materials Science  (3,598)
  • Biochemistry and Biotechnology  (623)
  • Physics  (324)
  • Physical Chemistry
  • 1995-1999  (1,462)
  • 1990-1994  (2,007)
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  • Articles  (4,412)
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  • 1
    Electronic Resource
    Electronic Resource
    Tissue reactions to bacteria-challenged implantable leads with enhanced infection resistance (1998)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 41 (1998), S. 142-153 
    Details
    ISSN: 0021-9304
    Keywords: biomaterials ; polyurethanes ; infection ; infection resistance ; surface modification ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Tissue reactions to implantable pacemaker leads were investigated in an early infection model in rabbits. Both standard leads and surface-modified leads were used. The surface modification technique was applied to achieve controlled release of the antibiotic gentamicin. The insulating polyurethane tubing material of the leads was provided with an acrylic acid/acrylamide copolymer surface graft and then loaded with gentamicin. Implantation periods varied from day 4, to week 3½, to week 10. We investigated tissue reactions in the absence of an infectious challenge and also the efficacy of surface-modified leads in preventing infection after challenge with Staphylococcus aureus was evaluated. It was demonstrated that the applied surface modification did not induce adverse effects although during early postimplantation an increase in infiltration of granulocytes and macrophages and wound fluid and fibrin deposition were observed. After bacterial challenge, standard leads were heavily infected at each explantation period, denoted by abscesses, cellular debris, and bacterial colonies. In contrast, little or no infection was observed, either macroscopically or by bacterial cultures, with the surface-modified leads. Microscopy showed little evidence of the bacterial challenge, and that primarily at day 4. It was concluded that the applied surface modification demonstrated enhanced infection resistance and thus represents a sound approach to the battle against infectious complications with biomaterials. © 1998 John Wiley & Sons, Inc. J Biomed Mater Res, 41, 142-153, 1998.
    Additional Material: 12 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    Synthesis and characterization of oxyethylene containing diisocyanates and polyimides therefrom N.C.L. Communication No. 4677. (1990)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 28 (1990), S. 1681-1691 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A facile synthesis of a series of oxyethylene containing diisocyanates, the α,ω-bis(isocyanatophenoxy)alkanes and bis[2-(isocyanatophenoxy)ethyl] ethers, is described. The key step involves the uneventful decomposition of the corresponding diacylazides to the diisocyanates in the Curtius rearrangement reaction. Further, eight thermally stable oxyethylene containing polyimides were synthesized by the polycondensation reaction of two meta- and two para-oriented diisocyanates, namely, 1,2-bis(3-isocyanatophenoxy)ethane and 1,2-bis(4-isocyanatophenoxy)ethane, and bis[2-(3-isocyanatophenoxy)ethyl] ether and bis[2-(4-isocyanatophenoxy)ethyl] ether, with pyromellitic dianhydride (PMDA) and benzophenonetetracarboxylic dianhydride (BTDA) in N,N-dimethylacetamide (DMAc). These polyimides were characterized by IR spectroscopy, x-ray diffraction, viscosity measurements, and thermogravimetric analysis.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1990.080280703
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  • 3
    Electronic Resource
    Electronic Resource
    Thermodynamic characterization of interpenetrating polymer networks of poly (carbonate-urethane) and poly (methyl methacrylate) (1994)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 32 (1994), S. 2625-2628 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Crosslinked poly (methyl methacrylate) and poly (carbonate-urethane) as well as full interpenetrating network on their base (IPN) were characterized by precise heat capacity measurements in the temperature interval 1.2-150 K. As judged by the positive sign of the excess Gibbs free energy in the whole temperature interval above 30 K, the apparently single-phase state of IPN is thermodynamically unstable; however, its kinetic stability is ensured by permanent chamical crosslinks prohibiting the incipient phase separation. © 1994 John Wiley & Sons, Inc.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1994.080321403
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  • 4
    Electronic Resource
    Electronic Resource
    High-rate continuous biodegradation of concentrated chlorinated aliphatics by a durable enrichment of methanogenic origin under carrier-dependent conditionsDedicated to the memory of Jean-Baptiste Boucquey (1970-1994). (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 47 (1995), S. 298-307 
    Details
    ISSN: 0006-3592
    Keywords: anaerobic biodegradation ; polychlorinated aliphatics ; acclimation ; enrichment ; polyurethaneactivated carbon carrier ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The simultaneous biodegradation of toxic compounds in mixtures is a major current concern. To bioremediate a toxic mixture, we designed a strategy combining an ad-sorbent carrier with an ecological and nutritional system which allowed work close to heavily polluted conditions in nature. Starting from a methanogenic community, we developed a microbial consortium acclimated to a mixture of about 30 chlorinated aliphatics in a fixed-film stationary-bed bioreactor. Prior to the establishment of a durable period of dechlorination, an interval of progressive dechlorination of the toxic mixture was observed during which the excess of the toxic compounds was stored on the carrier. The latter, consisting of activated carbon in a polyurethane foam, allowed us to work at concentrations far above the solubility of the toxic compounds (apparent concentrations of about 10 g/L). The complete disappearance of hexachloroethane as well as its lower homologues, penta-, tetra-, and trichloroethane, present in the toxic mixture, was observed. Additionally, octachlorocyclopentene, carbon tetrachloride, trichloro-ethylene, tetrachloroethylene, and hexachloro-1,3-butadiene also completely disappeared. For the four latter compounds, from mass balances in the bioreactor, degradation rates around 10 μmol/L per day were determined with total dechlorination. The enrichment culture thus developed exhibited high degradation performances similar to those reported in the literature for pure or enriched anaerobic microbial cultures in contact with a single toxic compound. The results demonstrate the possibility of concurrent high-rate degradation of several highly chlorinated toxic compounds, under conditions approximating field situations.© 1995 John Wiley & Sons, Inc
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260470304
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  • 5
    Electronic Resource
    Electronic Resource
    Effects of the kinetics of osmotic pressure variation on yeast viability (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 40 (1992), S. 1435-1439 
    Details
    ISSN: 0006-3592
    Keywords: osmotic pressure ; osmotic stress ; osmotolerance ; physiological state ; yeasts ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The variation rate of the osmotic pressure increase was found to have a great effect on the viability of yeasts subjected to hyperosmotic stress. A low intensity of the increase rate of osmotic pressure could maintain an important viability of the cells (about 90 to 100%) even for very high levels of osmotic pressure (about 108 Pa). The viability level was found to be highly dependent on the physiological state of the cells: Variations in the properties of the cell membrane were supposed to be involved in such a dependence. © 1992 John Wiley & Sons, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260401119
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  • 6
    Electronic Resource
    Electronic Resource
    On-line computer optimization chemostat productivityThis work originated as a practical experiment for the formal MS course in Biotechnology taught in this School. As there are still relatively few references describing on-line computer control of microbial processes, the results have been published in this communication. (1977)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 19 (1977), S. 575-581 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260190413
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  • 7
    Electronic Resource
    Electronic Resource
    Inhibition of microbial growth and metabolism by excess turbulence (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 38 (1991), S. 552-556 
    Details
    ISSN: 0006-3592
    Keywords: stirring ; turbulence ; shear effects ; lysine fermentation ; Brevibacterium flavum ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Excess turbulence caused by high-intensity stirring inhibited microbial growth and metabolism. In stirred tank bioreactors, the growth rate and lysine biosynthesis decreased in Brevibacterium flavum beyond 900 rpm, the growth rate of Trichoderma reesei on wheat straw beyond 150 rpm, and the growth rate of Saccharomyces cerevisae beyond 800 rpm. The term turbohypobiosis was introduced to describe this inhibition. Turbohypobiosis was characterized by a stress factor Fstr expressing the interaction of medium flow with microbial cells in local turbulent zones, dependent on the energy distribution of the stirring regime. Lysine synthesis was inhibited at significantly lower Fstr values than the growth of B. flavum. The main reason for the inhibition was shear effects causing decreased adenosine triphosphate (ATP) generation, lower O2 uptake, and lower specific growth rate of bacteria.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260380514
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  • 8
    Electronic Resource
    Electronic Resource
    Tarnishing of AuAgCu alloys. Choice of an accelerated test (1992)
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 43 (1992), S. 48-55 
    Details
    ISSN: 0947-5117
    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
    Description / Table of Contents: Anlaufen von AuAgCu-Legierungen. Auswahl eines beschleunigten Anlauf-TestsDas Anlaufverhalten von drei AuAgCu-Legierungen mit 14 und 18 ct sowie einer AuAgCuZn-Legierung mit 14 ct, die für dekorative Zwecke viel verwendet werden, wurde mit drei verschiedenen Anlauf-Tests geprüft, darunter zwei Gasphasen-Tests, nämlich (a) dem Schwefelblüten-Test (50 °C, 75% RF, 5 (d) und b) dem Thioacetamid-Test (Raumtemperatur, 75% RF, 5 d), und einem Flüssigphasen-Test, der als Tuccillo-Nielsen-Test bekannt ist und bei dem die Proben während 3 h alternierend in eine wässerige Sulfidlösung getaucht werden. Es wurde festgestellt, daß das in Feldversuchen gefundene Anlaufverhalten durch den Flüssigphasen-Test besser als durch die Gasphasen-Tests wiedergegeben wird. Die Verfärbungen sind aber beim Flüssigphasen-Test ungleichmäßiger. Der Hauptvorteil des Tuccillo-Nielsen-Tests liegt darin, daß er nur 3 h erfordert; andererseits können dabei leicht Kontakteffekte auftreten, und es kann schwierig sein, damit Endprodukte beliebiger Form zu prüfen. Der Thioacetamid-Test liefert schlecht reproduzierbare und wenig zuverlässige Ergebnisse außerdem sind die nach 5 d erhaltenen Farbänderungen gering, schließlich ist Thioacetamid auch kanzerogen. Der Schwefelblüten-Test liefert ausgeprägte, reproduzierbare Verfärbungen und ist daher bei der beschleunigten Prüfung von silber- und kupferhaltigen Legierungen dem Thioacetamid-Test vorzuziehen.
    Notes: Three tarnish-testing procedures were applied to three 14 and 18 ct AuAgCu and one 14 ct AuAgCuZn alloys widely used in decorative applications. Two gaseous phase tarnishing tests were investigated: (a)the flower of sulphur test carried out at 50 °C and 75% relative humidity for 5 days, and(B)the thioacetamide test performed at ambient temperature and 75% relative humidity for 5 days.In addition, a liquid based method known as the Tuccillo-Nielsen test where the samples are alternatively immersed in an aqueous sulphide solution for 3 h was also studied. It was found that the general tarnishing aspect encountered in field trials was better reproduced in the liquid medium than in the gas phase tests. The colorations are more heterogeneous in the liquid test. The main advantage of the Tuccillo-Nielsen test is that it requires only 3 h, but it can give rise to galvanic effects and may be difficult to apply to any forms of finished products. The thioacetamide test gave poorly reproducible and reliable results. In addition the colour changes after 5 days' exposure were small; moreover, thioacetamide is a carcinogen. The flower of sulphur test yielded large, reproducible colour changes. It should be preferred to the thioacetamide test for the accelerated testing of silver - and copper-containing alloys.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/maco.19920430203
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  • 9
    Electronic Resource
    Electronic Resource
    Tarnishing of AuAgCu alloys. Effect of the composition (1992)
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 43 (1992), S. 115-123 
    Details
    ISSN: 0947-5117
    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
    Description / Table of Contents: Anlaufen von AuAgCu-Legierungen: Einfluss der ZusammensetzungDie Anlaufbeständigkeit von zwei binären AuAg-, einer binären AuCu-, drei ternären AuAgCu- und einer quaternären AuAgCuZn-Legierung wurde mit zwei beschleunigten Anlaufprüfmethoden untersucht, und zwar dem in der Gasphase durchgeführten Schwefel-Ausblühungstest und dem in wässeriger Phase durchgeführten Tuccillo-Nielsen-Test. Die Anlaufschichten wurden colorimetrisch und coulometrisch analysiert. Die Farbe der meisten untersuchten Legierungen wurde durch das Anlaufen nach rötlich und gelblich verschoben. Zwischen der Farbänderung und der Kathodenladung wurde eine lineare Beziehung gefunden, was darauf hindeutet, daß die Dicke der Anlaufschicht ausreichend gering ist und daher eine lineare Beziehung zwischen Reflexionsvermögen und Filmdicke besteht. Bei den Legierungen mit hohem Silbergehalt war die Anlaufschicht so dick, daß Interferenzeffekte festzustellen waren; aus diesem Grunde wird das Anlaufen am besten durch die Kathodenladung charakterisiert. Es wurde gefunden, daß der Silbergehalt der Parameter ist, welcher die Anlaufbeständigkeit dominant bestimmt, doch spielt auch der Kupfergehalt eine gewisse Rolle. Das Anlaufen der binären AuAg-Legierungen kann als quadratische Funktion des Silbergehaltes ausgedrückt werden, während es sich bei den ternären und quaternären Legierungen um einen einfachen additiven Effekt des Silbers und Kupfers handelt.
    Notes: The tarnishing resistance of two AuAg binary, one AuCu binary, three AuAgCu ternary and one AuAgCuZn quaternary alloys was investigated using two accelerated tarnish testing procedures. The flower of sulphur test carried out in the gaseous phase and the Tuccillo-Nielsen method performed in an aqueous liquid solution were used. The tarnished layers were characterized by colorimetric and coulometric measurements. For most of the alloys, the colour turned both reddish and yellowish after tarnishing. A linear trend was found between the colour change and the cathodic charge, indicating that the thickness of the tarnished layer is small enough to be in the range where the reflectivity is linearly related to film thickness. For the high-silver alloys, the tarnished layer was thick enough to give rise to interference effects and therefore the tarnish is best characterized by the cathodic charge. It was found that the silver content is the dominant parameter influencing the tarnish resistance, but the copper content also plays a role. The tarnishing of AuAg binary alloys was interpreted as a quadratic function of silver content, while that of the ternary and quaternary alloys was found to be a simple additive effect of the silver and copper contributions.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/maco.19920430305
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  • 10
    Electronic Resource
    Electronic Resource
    Condensation of Co++ ions on chondroitin sulfate from transport coefficients and proton NMR measurements in aqueous solutions (1979)
    New York : Wiley-Blackwell
    Biopolymers 18 (1979), S. 1849-1857 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The “condensed” counterions which characterize high-charge-density polyelectrolyte solutions can be analyzed into two subpopulations: (1) site-bound counterions and (2) atmospherically entrapped counterions. The distinction is achieved experimentally by combining the data from self-diffusion coefficient or electrical mobility measurements, which give the amount of “condensed” ions, and those from nmr, chemical shift measurements, which indicate the amount of site-bound ions. In the case of a solution of chondroitin sulfate with excess Co++ counterions, it can be estimated that 20% of the structural charge of the polyion is neutralized by site-bound, dehydrated, condensed counterions, while a further 30% is neutralized by atmospherically entrapped, hydrated counterions.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1979.360180803
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