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  • 1
    Electronic Resource
    Electronic Resource
    Observations on the natural history of the Gulf of Mexico sturgeon (Acipenser oxyrinchus de sotoi Vladykov 1955) in the Suwannee River, southeastern United States (1996)
    Oxford, UK : Blackwell Publishing Ltd
    Ecology of freshwater fish 5 (1996), S. 0 
    Details
    ISSN: 1600-0633
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: From 1986 to 1994, we collected 3,098 Gulf of Mexico sturgeon (Acipenser oxyrinchus de sotoi) during their spring migration from the Gulf of Mexico to the Suwannee River, Florida. We estimated population size and described migratory and seasonal growth patterns of sturgeon in the Suwannee River, using data from tag returns, movement of ultrasonic-lagged fish and weight records. Population size estimates for 3.0- to 81.0-kg Gulf of Mexico sturgeon in the Suwannee River ranged from 1,504 to 3,066 fish. Sturgeon migrated from the Gulf of Mexico into the Suwannee River from mid-February to early May. Fish moved upstream and remained within a 2-km upstreamdownstream “home” area. These sites were closely associated with undenvater springs that discharge into the river. Sturgeon migrated downstream and into the Gulf of Mexico in October and November. In the Gulf of Mexico, ultrasonic-tagged fish were located in the Suwannee Sound area just north of Cedar Key, Florida. On an annual basis, fish gained an average of 20% of their body weight while in the Gulf of Mexico and lost about 12% of their weight during their stay in the Suwannee River. We observed movement of tagged sturgeon between the Suwannee and Apalachicola Rivers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1600-0633.1996.tb00130.x
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  • 2
    Electronic Resource
    Electronic Resource
    Electric field-induced structure in poly(acrylonitrile) (1979)
    Springer
    Colloid & polymer science 257 (1979), S. 913-919 
    Details
    ISSN: 1435-1536
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Summary Experimental evidence has been obtained for alteration of the molecular organization in polyacrylonitrile which has been given a thermoelectric treatment that creates a persistent electrical polarization. These studies have involved infrared spectroscopy and X-ray diffractometry, and their results have been interpreted as suggesting the existence of dipolar clusters in polarized material. These clusters cause polyacrylonitrile chains to adopt a structure which is different from any previously reported for this material. It is suggested that stability of the polarized state of polyacrylonitrile results, in part, from this new molecular organization.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01520713
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  • 3
    Electronic Resource
    Electronic Resource
    Morphologie und Deformation von aus der Schmelze gesponnenen Polyäthylen-Fasern (1974)
    Springer
    Colloid & polymer science 252 (1974), S. 182-182 
    Details
    ISSN: 1435-1536
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01555662
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  • 4
    Electronic Resource
    Electronic Resource
    Formation of bimodal crystal textures in polypropylene (1975)
    Springer
    Journal of materials science 10 (1975), S. 870-886 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Electron microscopy, selected area electron diffraction, X-ray diffraction, and dynamic-mechanical testing have been used to study flow-crystallized and hot drawn isotactic polypropylene. As a result of these investigations, it was found that bimodal crystal textures can apparently be formed by at least two different treatments, but the corresponding morphologies are completely different. Flow-induced crystallization was observed to result in a microstructure of lamellae oriented perpendicular to the flow direction, while hot drawing of polypropylene films above a critical temperature produced a morphology of microfibrils lying parallel to the draw direction. Below this critical temperature, drawing produced a fibrillar morphology having only a typical unimodal fibre texture. As a result of information obtained here, a mechanism involving epitaxial deposition of chain segments onto growing lamellae is concluded to be responsible for formation of the bimodal crystal texture in flow-crystallized material.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01163082
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  • 5
    Electronic Resource
    Electronic Resource
    Polypropylene fibers melt-spun in the presence of torsional shear (1975)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 19 (1975), S. 1755-1766 
    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: Melt-spun fibers of isotactic polypropylene have been formed using specific combinations of shearing and elongational flow. Such rheological conditions were achieved with a take-up device capable of subjecting molten polymer filaments continuously to various combinations of torsional and elongational strains. Relationships were determined between mechanical properties of the resulting fibers and their molecular organizations. The results obtained indicated that these flow fields would produce fibers whose mean-preferred-chain-orientation directions ranged between being tilted radially from a direction parallel with the fiber axis (no torsional shear strain imposed) and having some additional tilt that is tangential with respect to the fiber circumference (some torsional shear strain imposed). It is not possible to resolve the observed helical chain tilts into contributions from crystalline and amorphous regions, respectively.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1975.070190625
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  • 6
    Electronic Resource
    Electronic Resource
    Thermally stimulated discharge current studies on low-temperature relaxation in epoxy resin (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 25 (1980), S. 1355-1363 
    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: Thermally stimulated discharge current (TSDC) analysis has been used to characterize the low-temperature (100-300 K) molecular relaxation processes (β relaxation) of an epoxy resin. Experiments were performed on a resin system composed chiefly of tetraglycidyl-4,4′-diaminodiphenyl-methane and diaminodiphenyl sulfone (TGDDM/DDS). Polarization of the epoxy of the resin appears to be due to preferential orientations of dipoles in the temperature range studied. The broad β-dispersion peak exhibits considerable “structure,” and it promises to prove rich in information related to polarization and relaxation processes in the epoxy resins. It is seen that TSDC can reveal clearly the difference between the degree of curing for epoxy resins. Temperature dependence of a mean activation energy calculated from the discharging processes reveals several temperature ranges over which common molecular relaxation events are probably occurring.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1980.070250709
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  • 7
    Electronic Resource
    Electronic Resource
    Microbial degradation of polymer solids. I. Cellophane (1973)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 11 (1973), S. 313-329 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Specimens of regenerated cellulose films (cellophane) have been inoculated with cellulolytic fungi and the resulting degradation monitored through change in physical properties. Investigation of structure-property relationship in cellophane have revealed that surface microfibrils are highly oriented parallel to the manufacturing machine direction, while those in the film interior exist in a somewhat disordered array. Cellulase enzymes have been observed to diffuse appreciable distances from their point of application and to attack disordered regions more readily than the crystallites. Damage to surface microfibrils appears to involve their being cleaved into short segments. The fungus studied in this work forms a network of hyphae that covers much of the specimen surface soon after growth starts; hyphae penetrate into the film and proceed to remove its core more rapidly than surface layers. Tensile strength declines progressively as this degradation occurs, but vapor barrier properties remain essentially unchanged over the period of these studies. The suggests that intrusion of hyphae, in combination with enzymatic digestion of cellulose, rapidly lowers load-bearing characteristics, but moisture permeation rates stay nearly constant owing to the presence of fungal material at sites where cellulose has been removed.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1973.180110212
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  • 8
    Electronic Resource
    Electronic Resource
    Mechanical loss processes in polysaccharides (1976)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 14 (1976), S. 111-124 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Dynamic mechanical properties of cellophane, amylose, and dextran have been obtained over the temperature range 100-520°K and frequency range 10-2 to 10+2 Hz on specimens containing various amounts of water. Four mechanical transitions have been characterized. At about 180°K, there is a γ transition that has been assigned to rotation of methylol groups; no comparable transition was found to exist in dextran. At about 240°K, there is a β transition that has been assigned to rotation of methylol-water complexes, but the β transition in dextran appears to be due to some other kind of motion. In cellophane at about 450°K there is an α2 transition which appears to have contributions from motion of chain segments in disordered regions. The α1 transition for cellophane occurs at temperatures too high to measure and may be due to segmental motions in chains within crystalline regions. Dextran and amylose were found to have at these same temperatures α loss processes that probably correspond to glass-rubber transitions in amorphous material. The changes in these mechanical loss mechanisms due to moisture uptake suggest that sorbed water associates with glucose repeat units in ways ranging from those which stiffen molecular structure to those which allow greater freedom for other types of motion to occur.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1976.180140109
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  • 9
    Electronic Resource
    Electronic Resource
    Unit-cell dilation in model ethylene copolymers (1985)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 1563-1572 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Single crystals of model ethylene copolymers have been grown in dilute solution. The effects of narrow molecular weith distribution (MWD) and a perfectly random distribution of ethyl branches (ca. 17 per 1000 main-chain carbon atoms) on the unit cell of this ethylene copolymer analog were examined. X-ray diffraction on dried powder samples revealed expansions of up to 1.5% in a and 0.5% in b. a increased as a mild function of molecular weight; the dependence of b on MW was not as clearly defined. Electron diffraction studies on isolated suspensiongrown single crystals yielded lattice parameters much more strongly expanded. The large expansion in the basal plane of the unit cell is hypothesized to be accompanied by a fore-shortening of the projected c-axis distance. This is accomplished by and orthorhombic-to-hexagonal polymorphic transformation in which the chains are hypothesized to adopt a disordered helical conformation. The driving force for this transformation is electron irradiation damage of the single-crystal specimens. The rapidity of the transformation is believed to be due to the model polyethylene crystals being in a higher-energy, defect-containing condition prior to irradiation.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1985.180230809
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  • 10
    Electronic Resource
    Electronic Resource
    Morphology of poly(phthalocyaninatogermoxane) crystals (1985)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 305-313 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The morphology of fully and partially polymerized poly(phthalocyaninatogermoxane), [Ge(Pc)O]n, crystals was studied by both scanning and transmission electron microscopy. It was found that the morphological units are lath-like crystals which aggregate into particles. Generally speaking, the thickness, width, and length of the laths are in the range of 1000-2000 Å, 2000-10,000 Å, and 1-5 μm, respectively. Each lath may possess a mosaic substructure. Selected-area electron diffraction patterns indicate that the rigid, extended [Ge(Pc)O]n chains are parallel to the large surface of the lath, and in most crystals the chains lie parallel to the lengthwise direction of the lath. However, in several cases, the chain orientation is at an angle of about 60° with respect to the long edge of the lath. The electron diffraction results are in accord with a tetragonal crystal structure (P4/m).
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1985.180230206
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