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  • 1
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 7 (1951), S. 261-276 
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The intrinsic viscosity of cellulose xanthate solutions was studied as a function of the electrolyte content of the solvent, and found to decrease sharply with increase in electrolyte concentration. All electrolytes tested except sodium and lithium hydroxides produced essentially the same reduction in intrinsic viscosity for solutions of equivalent ionic strenghts, indicating that the effect was largely one of interaction between the solvent ions and the charged xanthate groups. Hydroxides induced a greater viscosity reduction. The reason for this was not fully resolved; however, indications were obtained that the hydroxides, in addition to behaving as electrolytes toward the charged xanthate groups, also interact with the hydroxyl groups on the parent cellulose chain.Light scattering measurements, as well as data on the variation of the intrinsic viscosity with molecular weight in various solvents, showed that the change in intrinsic viscosity with electrolyte concentration could be accounted for by a change in configuration, or degree of coiling of the molecule. Calculations indicated that in pure water cellulose xanthate should approach a rigid rod configuration whereas in 6% caustic coiling occurs and the molecule resembles more a random configuration.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Auger sputter profiles of thin AI films on InP are presented and shown to be susceptible to an unusual type of ion beam induced interfacial distortion. It is found that recoil implantation and atomic mixing produce a differential broadening of the In and P at the interface which can seriously affect the integrity of the Auger profile. Energy shifts in the AI Auger peak indicate that this distortion is associated with AIP formation to a depth dictated by the ion beam energy and species. Experimental requirements for the reduction of interfacial distortion are discussed. We also consider the influence of the ion beam on the topography and morphology of the InP surface in relation to interfacial distortion.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: As part of a process development campaign, studies have been conducted to determine the influence of induction temperature on the expression of two different malaria antigens, RN1 and RT2. Single-step temperature inductions, in which growth at 32.0°C is followed by a shift in temperature to a desired setpoint, show that there exists an optimum duration and temperature of induction which is product specific. Between an induction temperature of 39.5 and 44.5°C RN1 yield is constant at ca. 0.20 g/g total soluble protein (TSP). RT2 yield approaches 0.20 g/g TSP only at elevated induction temperatures. The optimum temperature of induction for RN1 production is 39.5°C, whereas, that for RT2 production is 41.0°C. Above the optimum temperature of induction antigen concentration decreases owing to decreases in biomass. Furthermore, the maximum concentration of these two antigens differ by a factor of four. With increasing temperature of induction the extent of proteolysis of the products also appears to increase.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 4
    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: Proton magnetic resonance has been used to study water in Douglas fir and western red cedar. The free induction decay, when combined with a knowledge of chemical composition of the wood, gives an accurate measure of the absolute moisture content. Spin-lattice relaxation was found to be significantly different for the two species. In sapwood, three distinct spin - spin relaxation times, T2, were measured and assigned, with the help of anatomical data, to water in and on the cell wall, water in the ray and latewood tracheid lumens, and water in the earlywood tracheid lumens. This T2 behavior was explained by a model in which free water in a void exchanges with a small fraction of bound water on the lumen surface. The three T2's were almost independent of moisture content, suggesting physically separate compartments. The behavior of the three water components during drying was studied. The fiber saturation point could be determined from a single T2 measurement on a green sapwood sample. Magnetic resonance imaging of logs was investigated.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Medical grade silicone rubber manufactured by Dow Corning Corporation was implanted subcutaneously in beagle dogs. At specified time intervals, the implants were removed at which time physical properties and weight changes were determined. A change in the physical properties was observed after six months implantation. Tensile strength decreased 7%, elongation 10% and the modulus at 200% extension increased 8%. After two years implantation, tensile strength had decreased 8%, elongation 15%, and 200% modulus increased 16%. After two weeks implantation, a 0.4% weight gain was seen, and after four weeks implantation the samples had gained 0.7%. However, after four weeks the weight gains stabilized and from four weeks to two years, they never exceeded 0.91%. The increase was due mainly to lipid absorption. No phospholipid or protein was detected. A chloroform/methanol extraction of the samples before implantation demonstrated 1.7% extractable silicone polymer. Samples not extracted before implantation, but extracted after implantation also demonstrated 1.7% extractable silicone polymer. This data suggests extractable silicone polymer does not leach from the medical grade silicone rubber during implantation.The data also suggests that the rubber is not being degraded to extractable silicone polymers during implantation. There were no significant differences in percent lipid up-take or the lipid profiles between samples which had extractable silicone polymer extracted before implantation and/or those which were not extracted before implantation.It should be pointed out that the slight changes in physical properties measured in this study should not be great enough to alter the performance of the rubber in the subcutaneous environment.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Publication Date: 2018-05-04
    Description: Severe malaria is caused by the apicomplexan parasite Plasmodium falciparum. Despite decades of research, the distinct biology of these parasites has made it challenging to establish high-throughput genetic approaches to identify and prioritize therapeutic targets. Using transposon mutagenesis of P. falciparum in an approach that exploited its AT-rich genome, we generated more than 38,000 mutants, saturating the genome and defining mutability and fitness costs for over 87% of genes. Of 5399 genes, our study defined 2680 genes as essential for optimal growth of asexual blood stages in vitro. These essential genes are associated with drug resistance, represent leading vaccine candidates, and include approximately 1000 Plasmodium -conserved genes of unknown function. We validated this approach by testing proteasome pathways for individual mutants associated with artemisinin sensitivity.
    Keywords: Microbiology, Online Only
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
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