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  • Cell & Developmental Biology  (942)
  • Chemical Engineering  (923)
  • 1980-1984  (1,212)
  • 1975-1979  (653)
  • 1950-1954
  • 1984  (1,212)
  • 1977  (653)
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  • 1980-1984  (1,212)
  • 1975-1979  (653)
  • 1950-1954
Year
  • 1
    Electronic Resource
    Electronic Resource
    Effects of folic acid upon filopodia of Dictyostelium discoideum vegetative amoebae (1984)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984), S. 129-135 
    Details
    ISSN: 0886-1544
    Keywords: amoeboid motion ; chemoattractants ; chemotaxis ; Dictyostelium ; filopodia ; folic acid ; pterins ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Living vegetative D. discoideum amoebae were studied to determine whether their filopodia respond to folic acid, a chemoattractant for these cells. Exponentially growing amoebae (ca. 10 μm diameter) exhibit 5-30 μm long filopodia; at stationary phase, aggregation competent amoebae have numerous multibranched filopodia up to 100 μm long. Folic acid was observed to stimulate production, elongation, and branching of filopodia with its effects progressively changing as the amoebae approach aggregation. Filopodial construction was also found to be dependent upon Mg2+ levels. The significance of these results is discussed with respect to progressive changes within the vegetative phase as well as to the mechanisms of amoeboid movement, pseudopodial activity, and chemotaxis.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970040206
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  • 2
    Electronic Resource
    Electronic Resource
    A quantitative comparison of cellular motile systems (1984)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984), S. 1-5 
    Details
    ISSN: 0886-1544
    Keywords: motility ; power output ; muscle ; flagella ; cytokinetic furrow ; mitotic spindle ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Cellular motile systems as diverse as muscle and the mitotic spindle have been compared by their specific power output: the maximum power they develop per unit of engine volume. Striated muscles and flagella have high specific output; their performance is comparable to that of typical automobile engines. The cytokinetic furrow and the mitotic spindle have very much lower specific power output. The furrow's output is 7,000 times lower than muscle and the spindle's is 300,000 times lower. Different macromolecules have been used to generate power in systems with similar output (muscles and flagella) and, conversely, the same macromolecular motor has been used in systems with very different output (muscles and cytokinetic furrows). The common feature amid this diversity is adaptation to a particular biological role, which specific power output reflects very well. High values are found where a powerful, compact engine should be advantageous, while low values are found where precision, not power, matters most.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970040102
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  • 3
    Electronic Resource
    Electronic Resource
    Announcement (1984)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984), S. 76-76 
    Details
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970040108
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  • 4
    Electronic Resource
    Electronic Resource
    Energy requirements for pigment aggregation in Fundulus melanophores (1984)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984), S. 431-441 
    Details
    ISSN: 0886-1544
    Keywords: dynein ; chromatophores ; permeabilization ; melanosomes ; motility ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Teleost chromatophores are filled with individual pigment granules that rapidly aggregate to the cell center or become dispersed throughout the cytoplasm in response to environmental stimuli. Microtubules appear to be required for pigment aggregation (movement toward the cell center), and recent findings have suggested that a dynein-like ATPase may participate in force production. Based on previous studies, however, it has been argued that pigment aggregation does not require energy directly, a view that supports the involvement of an elastic component in granule movement. To examine this point further, we have reinvestigated the energy requirements for pigment aggregation using both intact cells and detergent-permeabilized cell models of Fundulus melanophores. Poisons of oxidative phosphorylation, namely, 2,4 dinitrophenol and NaCN, reversibly inhibit melanosome aggregation in response to adrenaline. Inhibition of movement results directly from depletion of intracellular ATP, since pigment translocation can be reactivated in permeabilized cells by the addition of exogenous ATP to the lysis buffer. Non-hydrolyzable analogues, including β,γ-imidoadenosine-5′-triphosphate (AMPPNP), β,γ-methylene adenosine-5′-triphosphate (AMPPCP), and ATPγS, will not substitute for ATP in reactivation of movement. Similarly, other nucleotides such as ADP, AMP, GTP, CTP, and ITP, have limited ability to support melanosome aggregation in metabolically poisoned cells subjected to detergent lysis. ATP itself has no effect on intact cells. These results indicate that melanosome aggregation is ATP-dependent and energy-driven, and are consistent with a role for a force-transducing ATPase in particle movement.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/cm.970040604
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  • 5
    Electronic Resource
    Electronic Resource
    Observations of exocytosis in fucus vesiculosus gametes using video-enhanced light microscopy: A video report (1984)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984), S. 25-27 
    Details
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970040104
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  • 6
    Electronic Resource
    Electronic Resource
    An unusual mechanism of cell contraction: Leptodiscinae Dinoflagellates (1984)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984), S. 41-55 
    Details
    ISSN: 0886-1544
    Keywords: Leptodiscinae ; Dinoflagellates ; contractility ; non-actin filaments ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The Leptodiscinae, a group of marine Dinoflagellates, are good material for the study of contraction though they cannot be collected in abundance. Their cell bodies are flattened anteroposteriorly (Leptodiscus, Leptophyllus, and Leptospathium) and are able to contract suddenly when the surrounding water is disturbed.Electron microscopical observations have shown that the structures responsible for the contraction consist of a layer of parallel filaments located beneath the cell membrane of some specialized parts of the body. These filaments seem to be nonactin (NAF) because of their diameter (2.5-3 nm) and because they are not decorated by heavy meromyosin (HMM). They appear helically coiled and doubly twisted, and form tubular structures when contracted.
    Additional Material: 19 Ill.
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    URL: http://dx.doi.org/10.1002/cm.970040106
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  • 7
    Electronic Resource
    Electronic Resource
    A flagellar surface glycoprotein mediating cell-substrate interaction in Chlamydomonas (1984)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984), S. 77-87 
    Details
    ISSN: 0886-1544
    Keywords: Chlamydomonas ; flagella ; cell surface ; adhesion ; glycoproteins ; iodination ; lactoperoxidase ; Iodogen ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The Chlamydomonas flagellar surface exhibits interesting adhesive properties that are associated with flagellar surface motility. This dynamic surface property can be exhibited as the binding and movement of small polystyrene microspheres or as the interaction of the flagellar surface with a solid substrate followed by whole cell locomotion, termed “gliding.” In order to identify flagellar surface proteins that mediate substrate interaction during flagellar surface motility, two immobilized iodination systems were employed that mimic the conditions for flagellar surface motility: small polystyrene microspheres derivatized with lactoperoxidase, and large glass beads derivatized with Iodogen. Use of these iodination conditions resulted in preferential iodination of a high-molecular-weight glycoprotein with apparent molecular weight of 300,000-350,000. These results suggest this glycoprotein as a major candidate for the surface-exposed adhesive component that directly interacts with the substrate and couples the substrate to a system of force transduction presumed to be located within the flagellum.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/cm.970040202
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  • 8
    Electronic Resource
    Electronic Resource
    Masthead (1984)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984) 
    Details
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970040501
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  • 9
    Electronic Resource
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    Ca2+-dependent contraction of human lung fibroblasts treated with triton X-100: A role of Ca2+-calmodulin-dependent phosphorylation of myosin 20,000-dalton light chain (1984)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984), S. 315-331 
    Details
    ISSN: 0886-1544
    Keywords: fibroblast ; permeabilized cell model ; Ca2+-dependent contraction ; calmodulin ; phosphorylation ; myosin light chain ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Human lung fibroblast MRC-5 cells treated with Triton X-100 (MRC-5 cell models) were able to contract in the presence of MgATP and Ca2+ of more than 1 μM. Immunofluorescence microscopy with antibodies to actin and myosin 20,000-dalton (20 Kd) light chain revealed that stress fibers were prominent in MRC-5 cell models. Use of a fluorescent actin probe, 7-nitrobenz-2-oxa-1,3-diazole-phallacidin permitted visualization of contraction of the stress fibers in the presence of MgATP and Ca2+. Of the proteins in MRC-5 cell models, only a myosin 20 Kd light chain was phosphorylated in a Ca2+-dependent manner. This Ca2+-dependent phosphorylation of the 20 Kd light chain closely corresponded with the contraction of MRC-5 cell models: 1) Both phosphorylation of the 20 Kd light chain and contraction of MRC-5 cell models were inhibited by calmodulin antagonists such as N-(6-aminohexyl)5-chloro-1-napthalene sulfonamide. 2) The threshold Ca2+ concentration for phosphorylation of the 20 Kd light chain was similar to that for contraction of MRC-5 cell models. Both were lowered by exogenous calmodulin in a concentration-dependent manner. 3) The 20 Kd light chain was thiophosphorylated by incubation of MRC-5 cell models with an ATP analogue, adenosine 5′-0-(3-thiotriphosphate) only in the presence of Ca2+. After this treatment, MRC-5 cell models lost the Ca2+-dependence for contraction. These results indicate that Ca2+-calmodulin-dependent phosphorylation of myosin 20 Kd light chain is required for contraction of MRC-5 cell models.
    Additional Material: 10 Ill.
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    URL: http://dx.doi.org/10.1002/cm.970040503
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  • 10
    Electronic Resource
    Electronic Resource
    Time course of the motion of bull sperm flagella (1984)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984), S. 387-401 
    Details
    ISSN: 0886-1544
    Keywords: bull sperm flagella ; motility ; time course ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Detailed measurements were made of the time course of the motion of bull spermatozoa. Fourier analysis of the data showed the time course to be basically sinusoidal within 2% to 3%. An asymmetry in the motion was present, resulting in a second harmonic component in the Fourier spectra of normal sperm of approximately 11% of the main component. When the energy metabolism of the sperm was inhibited or when the external viscosity of the medium was raised, the asymmetry was reduced. When the internal Mg2+ content of the sperm was lowered, the asymmetry was increased. The asymmetries and the corresponding second harmonic components in the Fourier spectra were correlated with the overall bend shape of the sperm and with the curvature of the path in which the sperm were swimming. Model calculations showed that the asymmetry could reside in either the internal active moments in the sperms or in the stiffness of the sperm fiagella.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/cm.970040507
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  • 11
    Electronic Resource
    Electronic Resource
    Actin microfilaments in paramecium: Localization and role in intracellular movements (1984)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984), S. 443-468 
    Details
    ISSN: 0886-1544
    Keywords: actin ; microfilaments ; HMM ; phagocytosis ; cytochalasin ; Paramecium ; fluorescence microscopy ; electron microscopy ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Using heavy meromyosin (HMM) or the fragment S1 of myosin as probes for actin microfilaments, we studied their organization in Paramecium both by fluorescence and electron microscopy.In interphasic cells, HMM decorates (a) most prominently the periphery of nascent and young food vacuoles and their route during the early phase of their intracellular transit; (b) a thin meshwork radiating from the gullet throughout the cytoplasm; (c) a small area beneath the pore of contractile vacuoles and beneath the cytoproct when open to release food residues. Most of these HMM-decorated structures are in close contact with microtubular arrays. All HMM decoration disappears in dividing cells and in cytochalasin-treated cells. In vivo, the drug immediately blocks food vacuole formation but does not affect cytokinesis, cyclosis, contractile vacuole pulsation, defecation, or nuclear movements.The data show that, as in the cells of other organisms, actin microfilaments form defined arrays that undergo physiologically controlled cycles of assembly/disassembly. These arrays contribute (at least in the phagocytotic process) to diverse types of movement: constriction, membrane fusion, and migration of food vacuoles. However, aside from their massive concentration along the phagocytotic tractus, actin microfilaments are neither major structural components of Paramecium cytoplasm nor the only cytoskeletal components ensuring motility or contractility processes.
    Additional Material: 15 Ill.
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    URL: http://dx.doi.org/10.1002/cm.970040605
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  • 12
    Electronic Resource
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    A comparison of methods used to characterize gelation of actin in vitro (1984)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984), S. 197-213 
    Details
    ISSN: 0886-1544
    Keywords: gelation ; actin ; filamin ; cytoplasm ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We have compared the meniscus depletion assay and falling ball viscometry, two means of assessing the extent of gelation in actin-based systems using mixtures of actin and the actin-binding protein filamin. We examined the effect of varying the concentrations of actin and filamin in both assays. The interaction of actin and filamin was detected only above a threshold concentration of filamin. This threshold concentration was lower for falling ball viscometry than for the meniscus depletion assay at equal actin concentrations. At constant concentrations of filamin, an increase in actin concentration caused an increase in apparent viscosity measured by the falling ball assay, but a decrease in sedimentability detected by the meniscus depletion assay. The rate of sedimentation of actin was dependent on the molar ratio of actin to filamin. At each molar ratio, the sedimentation of actin was not dependent on the specific concentrations of actin and filamin used. The apparent viscosity was dependent on both the molar ratio and the specific concentrations of actin and filamin. To relate the present results to earlier studies, we examined mixtures of actin and filamin using a macroscopic assay of gelation (tube tipping assay), and polarized light microscopy. The effect of increasing filamin concentration in the four assays was compared at three actin concentrations. Mixtures of actin and filamin whose apparent viscosities were low enough to be estimated by falling ball viscometry were optically isotropic fluids that flowed out of inverted test tubes. Mixtures of actin and filamin in the range of sensitivity of the meniscus depletion assay were either viscous fluids or gels, and were either optically isotropic or anisotropic. Thus, the four assays provide different estimates of gelation. Both the meniscus depletion assay and falling ball viscometry can be used to determine relative gelation activity, but neither can be used as a quantitative assay of gelation.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/cm.970040305
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  • 13
    Electronic Resource
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    Interaction of bimane-labeled fluorescent tubulin with the isolated mitotic apparatus (1984)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984), S. 183-196 
    Details
    ISSN: 0886-1544
    Keywords: tubulin ; assembly ; mitotic apparatus ; bimane ; fluorescence microscopy ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Fluorescent derivatives of cellular proteins that retain their native characteristics have become useful probes to investigate the dynamics of specific cytoskeletal proteins. In the experiments reported here, a previously characterized fluorescent derivative of tubulin, bimane-tubulin [Wadsworth and Sloboda, 1982a], was used to investigate microtubule assembly in vitro. The results demonstrate that bimanetubulin was competent to assemble onto a variety of organizing centers in vitro, including microtubule organizing centers (MTOCs) present in homogenates of sea urchin eggs, isolated mitotic apparatuses (MAs), and lysed mitotic cells. When homogenates of fertilized sea urchin eggs containing MTOCs were incubated with bimane-tubulin at 37°C, discrete areas of linear fluorescence were observed. Only diffuse fluorescence was observed when calcium or colchicine was added to the homogenate or if the temperature was maintained at 0°C. Negative-stain electron microscopy of the fluorescent arrays revealed morphologically normal microtubules radiating from electron dense regions. When mitotic spindles, isolated in glycerol containing buffers and therefore cold stable, were incubated with bimane-tubulin, linear fluorescence was observed emanating from the spindle poles but not from the region occupied by the kinetochores. MAs incubated with bimane-labeled bovine serum albumin or bimane-labeled microtubule-associated proteins showed only diffuse fluorescence. However, when mitotic cells which were hypotonically lysed in the absence of detergents or microtubule stabilizing solvents, were perfused with bimane-tubulin intense fluorescence was observed in the asters and throughout the spindle. Two experiments suggested that the fluorescence observed in the results outlined above was due to the assembly of normal microtubules from the fluorescent subunits. First, the observed fluorescence was sensitive to cold temperataure, which is known to disassemble microtubules. Second, when the isolated, fluorescent MAs were examined by thin section electron microscopy, microtubules of normal diameter were seen. No aggregated material appeared associated with the walls of the microtubules, which might have been expected if the fluorescent protein was nonspecifically adsorbed to the microtubules. The results of these experiments demonstrate that isolated, stabilized MAs support the growth of new microtubules from the spindle poles while labile spindles, present in lysed cells, incorporate fluorescent tubulin throughout the spindle and asters. The significance of these results for hypotheses concerning microtubule assembly and disassembly during mitosis is discussed.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/cm.970040304
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  • 14
    Electronic Resource
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    Localization of the centriole and keratin intermediate filaments in PtK1 cells by double immunofluorescence (1984)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984), S. 241-247 
    Details
    ISSN: 0886-1544
    Keywords: cytoskeleton ; centrosome ; tonofilaments ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We present observations on the relative location of the centriole and keratin filament cap in motile PtK1 cells. Subconfluent cells were double labeled with anticentriole and antikeratin sera. These preparations revealed that the centriole is separate from, but neighboring, the keratin filament cap. Serial ultrathin sections confirm this observation. These observations are consistent with the idea that the microtubule organizing center and intermediate filament distribution center are not identical or concentric in PtK1 cells.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/cm.970040403
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  • 15
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    Announcement (1984)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984), S. 403-404 
    Details
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970040508
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  • 16
    Electronic Resource
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    Automated methods for estimation of sperm flagellar bending parameters (1984)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984), S. 417-430 
    Details
    ISSN: 0886-1544
    Keywords: flagella ; image analysis ; microcomputer ; motility ; parameter estimation ; Simplex method ; spermatozoa ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Parameters to describe flagellar bending patterns can be obtained by a microcomputer procedure that uses a set of parameters to synthesize model bending patterns, compares the model bending patterns with digitized and filtered data from flagellar photographs, and uses the Simplex method to vary the parameters until a solution with minimum root mean square differences between the model and the data is found. Parameters for Chlamydomonas bending patterns have been obtained from comparison of shear angle curves for the model and the data. To avoid the determination of the orientation of the basal end of the flagellum, which is required for calculation of shear angles, parameters for sperm flagella have been obtained by comparison of curves of curvature as a function of length for the model and for the data. A constant curvature model, modified from that originally used for Chlamydomonas flagella, has been used for obtaining parameters from sperm flagella, but the methods can be applied using other models for synthesizing the model bending patterns.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/cm.970040603
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  • 17
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    Dynamics of keratin filaments and the intermediate filament distribution center during shape change in PtK1 cells (1984)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984), S. 169-181 
    Details
    ISSN: 0886-1544
    Keywords: cytoskeleton ; motility ; cell spreading ; epithelial cells ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Reorganization of intermediate filaments during cell spreading is examined by immunofluorescence, electron microscopy, and time-lapse video microscopy. A juxtanuclear cap, believed to correspond to the intermediate filament distribution center, was observed to be spatially related to the organization of the intermediate filament network as cells spread. A keratin cap was observed, which appeared spontaneously in motile PtK1 cells. Cap formation may be a consequence of retraction of intermediate filaments from the cytoplasm as cells move. The position of this juxtanuclear cap is related to the direction of movement, located on the side of the nucleus near the advancing edge of the cell. As the cell spreads, the cap disappears as the keratin filament network returns to the cytoplasm. Evidence presented here is consistent with the hypothesis that the distribution center mediates keratin filament organization during cell shape change.
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    URL: http://dx.doi.org/10.1002/cm.970040303
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  • 18
    Electronic Resource
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    Microfilament rearrangements during fibroblast-induced contraction of three-dimensional hydrated collagen gels (1984)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984), S. 29-40 
    Details
    ISSN: 0886-1544
    Keywords: microfilaments ; microtubules ; contraction ; collagen gel ; fibroblasts ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In vitro models have been developed recently to study the ability of fibroblasts to generate tensile force within collagen gels. The present study was initiated to assess the role of the cytoskeleton in the cell shape changes and force generation in one such model system. Porcine periodontal ligament fibroblasts (PPLF) were cultured within three-dimensional collagen gels attached to glass coverslips. Fluorescence microscopy, using nitrobenzooxadizole (NBD)-phallacidin labeling for microfilaments and tubulin antibody staining for microtubules, was combined with phase and Nomarski optics to determine the intra- and extracellular architecture of the cells and collagen fibers. Samples were observed from 30 minutes to 24 hours after initiation of cell attachment. During attachment and spreading, NBD-phallacidin staining changed dramatically until large microfilament bundles became prominent. Collagen fiber alignment, compaction, and finally tearing from the coverslip occurred during this time. After release of tension, microfilament bundles were no longer evident. The change in microtubule distribution during these processes was less dramatic, appearing to follow the change in cell shape. These results indicate that microfilaments play an essential role in generating force to align and compact collagen, while microtubules may have a secondary role only.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/cm.970040105
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  • 19
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    Induction of shape transformation in sea urchin coelomocytes by the calcium ionophore A23187 (1984)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984), S. 57-71 
    Details
    ISSN: 0886-1544
    Keywords: actin ; calcium ; coelomocytes ; ionophore ; pH ; shape transformation ; video microscopy ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We have investigated the ability of the Ca+ + ionophore A23187 to induce the transformation of petaloid sea urchin coleomocytes to the filopodial form. The response of individual cells to different media was observed with time-lapse phasecontrast video microscopy. In the presence of 1 mM CaCl2, isotonic medium containing 1-5 μM A23187 produces a similar shape transformation to that caused by hypotonic shock. Higher concentrations of ionophore (10-20 μM) induce the formation of filopodia that are thinner and less rigid than those generated by hypotonic shock or low doses of ionophore. A23187 also induces shape transformation in highly flattened cells that do not respond fully to hypotonic shock. The induction of cytoplasmic alkalinization by NH4Cl, methylamine-HCl, or the Na+ ionophore monensin does not induce shape transformation, suggesting that increased intracellular pH is not the stimulus for this process. Ultrastructural changes in cytoskeletal organization were examined in negatively stained detergent-extracted cells. Low doses of ionophore produce filopodia that are indistin-guishable from those of hypotonically shocked cells, with actin filament bundles that are straight and cohesive along their entire length. High concentrations of ionophore produce filopodia with filament bundles that branch repeatedly and splay apart near their tips, forming loops and irregular curves. These results suggest that an increase in intracellular free Ca+ + concentration acts as the trigger that stimulates coelomocyte shape transformation, but that abnormally high concentrations of intracellular Ca+ +, produced by high doses of ionophore, interfere with actin filament bundling.
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    URL: http://dx.doi.org/10.1002/cm.970040107
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  • 20
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    Nucleotide specificity for reactivation of organelle movements in permeabilized axons (1984)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984), S. 121-128 
    Details
    ISSN: 0886-1544
    Keywords: axonal transport ; ATP ; nucleotides ; saltatory movement ; dynein ; video microscopy ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In a permeabilized axon model, exogenous ATP can reactivate intraaxonal saltatory organelle movements (microscopically visible manifestations of fast axonal transport). We have studied the dependence of the reactivated movements on the ATP concentration and have also examined the nucleotide specificity of the reactivation. Organelle transport was visualized in isolated lobster giant motor axons using Nomarski optics and video microscopy. The axons were permeabilized with saponin, and movement was reactivated with ATP or other nucleotides. Some slight movement was seen with ATP concentrations as low as 10 μM. The velocity and frequency of the reactivated transport increased with increasing ATP concentrations up to about 5 mM. Movement was also reactivated by deoxyadenosine triphosphate, but not by AMP-PNP (a nonhydrolyzable ATP analogue), ADP, or AMP. Although other nucleotides (CTP, GTP, UTP, ITP) could reactivate transport, movement equivalent to that produced by 0.1 mM ATP was only seen with tenfold or greater concentrations of the other nucleotides. This pattern of specificity is consistent with the hypothesis that a dynein-like ATPase, rather than a myosin, is involved in fast axonal transport.
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    Selective immunocytochemical detection of fluorescent analogs with antibodies specific for the fluorophore (1984)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984), S. 137-149 
    Details
    ISSN: 0886-1544
    Keywords: anti-fluorescein ; fluorescent analog cytochemistry ; molecular cytochemistry ; microinjection ; actin ; acetamidofluorescein-actin ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Fluorescent analogs of cellular components are finding increasing use in the field of cell biology. The power of this technique can be augmented by the use of antibodies specific for the fluorophore to visualize selectively the fluorescent analog at the electron microscope level. Rabbit antibodies specific for fluorescein were elicited and purified according to published methods (Lopatin and Voss [1971]: Biochemistry 10:208). Immune sera and IgG formed precipitin lines with fluorescein-labeled proteins in Ouchterlony immunodiffusion assays, and significantly quenched the fluorescence of fluorescein-labeled proteins. Immune IgG and Fab fragments decorated fluorescein-labeled actin, but not unlabeled actin, in negative-stained preparations. Anti-fluorescein IgG was used for immunofluorescent localization of fluorescein-labeled actin following microinjection of the fluorescent analog into living cells. This approach was extended to the immunoelectron microscopic localization of the injected analog at the subcellular level by the use of an electron-dense marker coupled to goat anti-rabbit IgG. Many other fluorescent probes also can be used as haptens for production of antibodies. Therefore, a general method for localizing fluorescently labeled molecules at the electron microscopic level is now available. Several other applications of anti-fluorescein antibody in studies involving fluorescent analogs are also suggested.
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    Three-dimensional bend propagation in hamster sperm models and the direction of roll in free-swimming cells (1984)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984), S. 215-226 
    Details
    ISSN: 0886-1544
    Keywords: sperm motility ; flagellum ; axoneme ; microscopy ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Iontophoretic application of ATP to the flagellum of the demembranated hamster spermatozoon produced a planar pair of bends at the two ends of the stimulated site. During bend propagation, torsion appeared in the vicinity of the interbend in some responses such that the distal bend was twisted clockwise when viewed from the base of the flagellum. This pattern of propagation is consistent with the instantaneous configurations of free-swimming cells previously described. The technique used here establishes that the three dimensionality arises from propagation per se, and does not depend on forces developed during swimming. The rolling of both free-swimming intact and demembranated spermatozoa was examined by two-color darkground videomicroscopy and the direction of rotation was, as predicted, always anticlockwise. A hypothetical mechanism, involving differential speeds of propagation of active sliding within the active microtubule subset, is proposed to account for the observed waveforms.
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    Masthead (1984)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984) 
    Details
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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    URL: http://dx.doi.org/10.1002/cm.970040401
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    Axonal elongation as a stochastic walk (1984)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984), S. 351-370 
    Details
    ISSN: 0886-1544
    Keywords: axon ; rate ; nervous system ; tissue culture ; cell growth ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A new formula calculates rates of directed axonal growth (elongation or retraction) using measurements of growth cone movements. By explicitly separating changes in axonal length from other nonelongational growth cone movements, the calculated rates reflect the detailed cellular growth mechanisms more directly than previous growth measures. In addition, the formula produces three distinct parameters of axonal elongation: n, a growth step rate; s, a growth step size; and P, a probability that a growth step leads to axonal elongation. For normal and regenerating individual chick and frog axons in culture, the formula has quantitated the following differences: the axon itself can elongate more rapidly in the chick, and the axon elongates in smaller steps in the chick. The underlying dynamics of growth of regenerating axons are quite similar to normal axons, but, in the short term, regenerating axons elongate in larger steps and at a slower rate. The distribution of these new rate measurements suggests that the elongation of axons can be usefully modelled as a one-dimensional stochastic walk.
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    Microtubule crossbridging by Chlamydomonas dynein (1984)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984), S. 371-385 
    Details
    ISSN: 0886-1544
    Keywords: microtubules ; dynein ; tubulin ; cilia and flagella ; microtubule associated proteins ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Dynein, obtained from axonemes of Chlamydomonas, binds by both its A and B ends to microtubules assembled from twice cycled (2 ×) and purified (6S) brain tubulin as well as to microtubules in native spindles, thereby inducing microtubule crossbridging. The two ends of the dynein arm exhibit distinct binding characteristics for the different microtubule preparations. Greater than 99% of the dynein arms are bound exclusively by their B ends to microtubules assembled from 6S tubulin in the presence of dynein and decorated to saturation. In contrast, greater than 80% of the dynein arms are bound by both their A and B ends to and, therefore, crossbridge 6S microtubules that are only partially dynein decorated. Binding of the A end of the dynein arm to saturated 6S microtubules can be enhanced by destabilizing the binding of the B end upon addition of ATP and vanadate. These observations suggest that Chlamydomonas dynein arms can bind by their A ends to microtubules assembled from 6S tubulin only when the B ends of the arms either are not bound or are bound but do not occupy all available dynein binding sites. Dynein exhibits a slight preference for binding by its A end to microtubules assembled from 2 × tubulin and containing microtubule associated proteins (MAPs). Approximately 90% of the dynein arms crossbridge adjacent 2 × microtubles that are only partially decorated. But as saturation of these microtubules with dynein is approached, the majority of the arms are bound solely by their A ends, while a smaller percentage are bound by their B ends or by both their A and B ends. These studies indicate that the type of microtubule as well as the degree of saturation of the microtubule with dynein can determine whether microtubule crossbridging occurs.
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    Formation of myofibrils in spreading chick cardiac myocytes (1984)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984), S. 405-416 
    Details
    ISSN: 0886-1544
    Keywords: cardiac muscle ; myofibril ; cell spreading ; Z bands ; alpha-actinin ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Cardiac myocytes were isolated from 5-6-day-old chick embryos and allowed to spread in culture. The distribution of alpha-actinin in the cells was followed for five days in culture by exposing permeabilized cells to rhodamine-labeled alpha-actinin and also by injecting the labeled alpha-actinin into living myocytes. In addition to labeling the Z bands of sarcomeres, the added alpha-actinin also labeled small particles that were usually arranged periodically in linear arrays with a spacing between particles of 0.3-2.0 μm. Actin was localized between the particles of alpha-actinin by means of fluorescein-labeled heavy meromyosin. The punctate localization of alpha-actinin was prominent in pseudopods, behind ruffles, and at the periphery of spreading cells. Long rows of particles of alpha-actinin were often parallel to one another with the alpha-actinin particles in register. These linear arrays appeared to merge laterally to form strands with broader concentrations of alpha-actinin. Other linear arrays were parallel to myofibrils in the cell and some extended outward from the ends of myofibrils. We conclude that during spreading of cardiac myocytes, myofibrils form at the cell periphery behind the extending margins of the cell, and that the aggregates of alpha-actinin found in these areas are nascent Z bands in the forming myofibrils.
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    Mechanics of cytogels I: Oscillations in Physarum (1984)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984), S. 469-503 
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    ISSN: 0886-1544
    Keywords: cytogel ; actomyosin ; Physarum ; oscillations ; mechanics ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The contractility of actomyosin gels is the basis for a variety of cellular motility phenomena. We present here a mechanical analysis of contractile gels. By making certain hypotheses on the chemical regulation of cytogel contraction we formulate a model for the rhythmic contractions of plasmodia in the slime mold Physarum polycephalum which is in accord with a number of experimental observations.
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    Masthead (1984)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984) 
    Details
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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    URL: http://dx.doi.org/10.1002/cm.970040101
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    Rheological properties of living cytoplasm: A preliminary investigation of squid axoplasm (Loligo pealei) (1984)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984), S. 7-23 
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    ISSN: 0886-1544
    Keywords: axoplasm ; elastic modulus ; viscosity ; motility ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A magnetic sphere viscoelastometer has been developed to peform rheological experiments in living axoplasm of Loligo pealei. The technique includes the use of a calibrated magnetic sphere viscoelastometer on surgically implanted ferro-magnetic spheres in intact squid giant axons. The axoplasm was discerned to be “living” by the biological criterion of tubulovesicular organelle motility, which was observed before and after experimentation. From these in vivo experiments, new structural characteristics of the axoplasm have been identified. First, analysis of magnetic sphere trajectories has shown the axoplasm to be a complex viscoelastic fluid. Directional experimentation showed that this material is structurally anisotropic, with a greater elastic modulus in the direction parallel to the axon long axis. Second, both magnetic sphere and in vivo capillary experiments suggested that the axoplasm is tenaciously anchored to the axolemma. Third, it was found that axoplasm could be modelled as a linear viscoelastic material in the low shear rate range of 0.0001 to 0.004 s-1. The simplest mechanical model incorporating the discovered properties of the material in this range is Burger's model.
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    Masthead (1984)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984) 
    Details
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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    URL: http://dx.doi.org/10.1002/cm.970040601
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    Mitochondrial motility in axons: Membranous organelles may interact with the force generating system through multiple surface binding sites (1984)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984), S. 89-101 
    Details
    ISSN: 0886-1544
    Keywords: fast axonal transport ; mitochondria ; membrane receptors ; cytoskeleton ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In living tissue, membrane-bound organelles, including mitochondria, move along parallel cytoplasmic pathways. Motion is directed and tends to be confined to a single path. Deviations from this single path motion are rare. When present, however, they tend to occur at points of intersection of cytoskeletal linear elements (LE). Such intersections are relatively uncommon in intact axons and extruded axoplasm. However, we have found that such intersections can be produced in extruded preparations by shear forces directed tangential to the axoplasmic surface.We have studied the detailed behavior of mitochondria in extruded squid axoplasm. Special attention was directed to the relationship between mitochondrial shape changes and orientation of cytoskeletal LE. The most striking of these changes in shape is branching. In this process, the mitochondrion transiently assumes a triradial (three-ended) shape. This appearance may be maintained for seconds to minutes before the normal cylindrical shape is resumed by absorption of either the newly formed end or, more commonly, one of the original ends. The frequency of branching appears to be dependent on the degree of cytoskeletal organization. It becomes more common as the number of apparent intersections between cytoskeletal LE increases. Further, the formation of new ends seems to occur along paths defined by cytoskeletal elements.These observations suggest that the mitochondrial membrane is multivalent. That is, it contains multiple sites capable of interacting with the axonal force generation apparatus. Furthermore, LE in the cytoskeleton may indicate the paths along which these interactions are permissible.
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    Masthead (1984)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984) 
    Details
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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    Taxol stabilization of mitotic spindle microtubules: Analysis using calcium induced depolymerization (1984)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984), S. 155-167 
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    ISSN: 0886-1544
    Keywords: taxol ; microtubules ; mitosis ; mitotic spindle ; calcium ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Taxol stabilizes or promotes the assembly of microtubules. In this report we characterize the rate, extent, and reversibility of taxol stabilization of calciumlabile microtubules in isolated mitotic spindles, principally from embryos of the sand dollar Echinarachnius parma. The intense depolymerizing action of 100 μM Ca2+ was used to assess the extent of stabilization by taxol. Changes in spindle microtubule assembly were evaluated and recorded by measuring changes in spindle birefringent retardation (BR). Membrane-free mitotic spindles, isolated with a calcium-chelating, nonionic detergent buffer, were stored in an EGTA-gylcerol storage buffer to prevent microtubule depolymerization. When perfused with an EGTA-buffer without glycerol, microtubules in these isolated spindles depolymerized gradually over 60-120 min; but in isolated spindles perfused with buffer that contained 100 μM Ca2+, BR decreased by 90% within 2-5 sec. In contrast, spindles that were pretreated for 3 min with 1 μM taxol, or for about 30 sec with 10 μM taxol, lost less than 10% of their initial BR when perfused with buffer containing 100 μM Ca2+. The rate and extent of microtubule stabilization by taxol depended on both the concentration and the duration of exposure to taxol. Taxol stabilization was reversible. After a 15 min preincubation with 1 μM or 10 μM taxol then washout, stability of spindle BR to 100 μM Ca2+ decreased exponentially with a time constant of 30-60 min. Thus taxol dissociates from spindle microtubules at significant rates; taxol-stabilized microtubules are not “fixed.”
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    Announcement (1984)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984), S. 304-305 
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    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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    Evidence against surf-riding as a general mechanism for surface motility (1984)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984), S. 305-314 
    Details
    ISSN: 0886-1544
    Keywords: cell surface motility ; axopodia ; reticulopodia ; Allogromia ; Echinosphaerium (Actinosphaerium) nucleofilum ; surf-riding ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The mechanism responsible for the energy-dependent movement of membrane components (ie, surface motility) is unknown. Recently a potentially unifying model, termed “surf-riding” [Hewitt, 1979] or “surf-boarding” [Berlin and Oliver, 1982], has been proposed to explain surface motility. Using phase-contrast light microscopy and membrane surface markers (polystyrene microspheres), we have tested the surf-riding/surf-boarding hypothesis on two protozoan systems: the axopodia of the heliozoan Echinosphaerium nucleofilum and the reticulopodial networks of the allogromiid foraminiferans Allogromia laticollaris and Allogromia sp, strain NF. Our evidence indicates that surface motility, as displayed by these organisms, does not occur by a surf-riding/surf-boarding mechanism. Previouś observations on surface motility associated with the Chlamydomonas flagellum indicate that this system is also incompatible with the surf-boarding/surf-riding hypothesis.
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    Differential distribution and function of microtubules and microfilaments in sea urchin coelomocytes (1984)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984), S. 269-281 
    Details
    ISSN: 0886-1544
    Keywords: microtubules ; microfilaments ; filopodia ; cell spreading ; coelomocytes ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Sea urchin coelomocytes were used as a model system to investigate the distribution and role of microtubules and microfilaments in cell spreading and filopodial formation. By using immunoblot characterized antisera to tubulin and actin coupled with immunofluorescence techniques, cellular protrusions were seen to contain actin filaments but no microtubules. Cells depleted of MT's by cold and colcemid treatments could attach, spread, and transform to the filopodial morphology normally.
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    Direct visualization of particle velocity distribution by pseudostereoscopic viewing of time-lapsed sequential images: Application to fast axonal transport (1984)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984), S. 231-239 
    Details
    ISSN: 0886-1544
    Keywords: pseudostereoscopy ; particle speed distribution ; velocity distribution ; fast axonal transport ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We describe a simple method for direct visualization of the velocity distribution of particles moving against an immobile background. The technique involves pseudostereoscopic viewing of image pairs separated by an appropriate time interval in a sequential recording of the subject. Under these conditions, the positive or negative parallax arising from particle motion results in the binocular image of a particle being perceived as raised or lowered relative to an immobile background plane depending on its direction of movement, and with the degree of perceived elevation being proportional to its speed. In effect, the binocular optic axis becomes a velocity (speed) axis under these conditions. The technique is illustrated with examples of image pair sequences showing fast axonal transport in lobster and squid axons using video-enhanced differential interference contrast microscopy. However, the pseudostereoscopic method is quite generally applicable to both microscopic and macroscopic time-dependent phenomena. Particle speeds can be quantitated using standard procedures for measuring frame-to-frame particle displacements, or alternatively, by determination of parallax using stereogrammatic methods. It should be also readily adaptable for on-line monitoring of particle velocity distribution, particularly in video systems where frame buffers can be utilized to extract and present serial image pairs having any desired time separation from video-taped sequences.
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    Mutants in paramecium tetraurelia defective in their axonemal response to calcium (1984)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984), S. 283-295 
    Details
    ISSN: 0886-1544
    Keywords: axonemal mutants ; Ca++ response ; ciliary reversal ; electrophysiology ; models ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Six mutants of Paramecium tetraurelia, which display altered axonemal responses to Ca++, are described. The mutants, designated atalantas, are impaired in their ability to swim backward when stimulated by ions or heat; instead they spin very rapidly in one place. Three mutants, ataA1-3, are completely unable to swim backward. The three lines, however, can be distinguished from one another by their forward swimming velocities. The remaining three mutants are leaky. ataB swims backward briefly when stimulated, then stops and spins in place. ataC and ataD are extremely leaky and only display the spinning phenotype at elevated temperatures. An electrophysiological analysis reveals that all six mutants have normal membrane properties, including the Ca++ inward current under voltage clamp. When the membrane is disrupted so as to allow the axoneme free access to Ca++, wild-type cells swim backward, but the mutants do not. These data indicate the site(s) of lesion in the mutants is in the axoneme or in some step linking Ca++ influx and the axoneme, not within the ciliary membrane. These mutants may be useful in investigating the role of Ca++ in the regulation of axonemal motion.
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    Light microscopic observations on the release of vesicles by isolated chromaffin cells (1984)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984), S. 297-303 
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    ISSN: 0886-1544
    Keywords: exocytosis ; chromaffin cells ; vesicle release ; light microscope ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Cultured bovine adrenal medullary chromaffin cells were stimulated with the secretogogues Ba2+ or carbamyl choline plus Ca2+. With video-enhanced contrast, differential interference contrast microscopy, small vesicles were found to appear on the cell surface during stimulation. The structures were of lower refractive index than the cytoplasm, and their appearance required several tenths of a second. The vesicles are thought to correspond to omega figures seen with electron microscopy due to exocytosis. Many of the structures disappeared within a few seconds, but some appeared to coalesce into larger structures. The large structures may lead to the vacuoles that have been demonstrated to be present following stimulation. The nature of the cellular elements responsible for the vesicle which appeared on the surface was not found with either differential interference or interference reflection microscopy. The simplest explanation is that the refractive index of the elements is similar to that of the cell, and therefore the elements cannot be seen.
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    Masthead (1984)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984) 
    Details
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970040201
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    The effects of serum immunoglobulins on the metachronal coordination of the lateral cilia of Mytilus edulis (1984)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984), S. 103-119 
    Details
    ISSN: 0886-1544
    Keywords: cilia ; metachrony ; serum immunoglobulins ; IgM ; Mytilus edulis ; cystic fibrosis ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Human IgM and a bovine, IgM-enriched serum fraction isolated from normal adult serum at concentrations of 0.25-1 mg/ml protein induced a pronounced increase in the metachronal wavelength of the lateral (L) cilia of the sea mussel Mytilus edulis without altering their beat frequency. This change in activity was indistinguishable from that induced by 50% adult human or bovine serum. At protein concentrations ranging from 1-9 mg/ml, human IgG or a bovine, IgG-enriched serum fraction had no or little effect on the activity of the L cilia. Similarly, neither monomeric (8S) human IgM (0.25 mg/ml) nor monospecific pentameric IgM (1 mg/ml) isolated from Waldenström's macroglobulinemia patients altered the metachrony of the L cilia. Indirect immunofluorescence demonstrated that both bovine and human IgM became attached almost exclusively to the L cilia, while very little bovine or human IgG was found to associate with these cilia.The results of this study suggest that serum IgM specifically binds to the L cilia of Mytilus in an antigen-antibody manner and agglutinates adjacent cilia into blocks or bundles, thereby increasing the coupling between cilia. As a result, the wavelength of the metachronal coordination is increased. The origin of these ciliary antibodies and their significance to ciliary bioassays used to monitor serum for the detection of cystic fibrosis are discussed.
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    International Society of Developmental Biologists presents Tenth International Congress of ISDB August 4-9, 1985, Baltimore Hotel, Los Angeles, California, USA. New Discoveries and Technologies (1984)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984), S. 151-153 
    Details
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970040208
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    International Society of Developmental Biologists presents Tenth International Congress of ISDB August 4-9, 1985, Baltimore Hotel, Los Angeles, California, USA. New Discoveries and Technologies (1984)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984), S. 227-229 
    Details
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970040307
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    Trifluoperazine-induced changes in swimming behavior of paramecium: Evidence for two sites of drug action (1984)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984), S. 249-267 
    Details
    ISSN: 0886-1544
    Keywords: Paramecium ; trifluoperazine ; cilia ; calmodulin ; calcium ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Trifluoperazine (TFP), a drug that binds to Ca2+-calmodulin (CaM) complexes, altered swimming behavior not only in living paramecia, but also in reactivated, Triton-extracted “models” of the ciliate. By comparing the responses of living cells and models, we have ascertained that two sites of drug action exist in paramecium cilia. Swimming movements were recorded in darkfield stroboscopic flash photomicrographs; this permitted accurate quantitation of velocities and body-shape parameters. When living paramecia were incubated in a standard buffer containing 10 μM TFP, their speed of forward swimming fell over several minutes and their bodies shortened. Untreated paramecia backed up repeatedly and frequently upon transfer to a solution containing barium ions (the “barium dance”), but cells preincubated in TFP did not “dance.” Instead they swam forward slowly for long periods of time without reversing and occasionally then exhibited abnormally prolonged reversals. W7 effects on swimming mimicked low doses of TFP, and the analog W5 did not visibly alter normal swimming patterns. These results suggest that TFP induces a decrease in the intracellular pCa of living paramecia, perhaps by reducing the efficiency of a calmodulin-activated calcium pump in the cell membrane. Paramecia extracted with Triton X-100 and reactivated to swim forward (7 ≥ pCa ≥ 6) were not affected by addition of up to 40 μM TFP to the reactivation medium. We conclude that the main drug effect in living cells is probably not at the axoneme. However, at low pCa, TFP directly affected the ciliary axoneme to shift its behavior to one characteristic of a higher pCa: TFP inhibited backward swimming in models reactivated at pCa 〈 6; instead they swam forward or rocked in place. The mechanism of ciliary reversal in paramecium may therefore depend on an axonemal Ca+-sensor, possibly bound CaM, which is affected by TFP only at low pCa, as has been postulated for other types of cilia.
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    Cytoplasmic tubulin from the unfertilized sea urchin egg: II. Variation of the intrinsic calcium sensitivity of strongylocentrotus purpuratus egg tubulin as a function of temperature and brain microtubule-associated proteins (1984)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984), S. 333-350 
    Details
    ISSN: 0886-1544
    Keywords: microtubule ; tubulin ; MAPs ; calcium ; mitosis ; unfertilized sea urchin egg ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Cytoplasmic tubulin purified from unfertilized sea urchin eggs self-assembles in the absence of microtubule-associated proteins (MAPs) [Suprenant and Rebhun, 1983; Detrich and Wilson, 1983] with a critical concentration for polymerization of 0.8 mg/ml at 15-18°C, a value well below the 3 mg/ml tubulin present in these eggs [Pfeffer et al, 1976]. Studies of the calcium sensitivity of unfertilized S. purpuratus (sea urchin) egg tubulin were initiated to help understand how this tubulin is maintained unassembled in the unfertilized egg. Egg microtubules, assembled at physiological temperatures (15-18°C) were depolymerized by a 100-fold lower free calcium concentration than egg microtubules assembled at the higher temperatures (25-37°C) generally used to assemble mammalian brain microtubules. The initial rate of egg microtubule assembly was much more sensitive to calcium than was microtubule depolymerization at steady state at 37°C. However, both processes were sensitive to near physiological free calcium of free calcium for depolymerization than microtubules assembled at 18°C from egg tubulin alone. While calcium regulatory MAPs have not yet been found in sea urchin eggs, the fact that brain MAPs interact with egg tubulin and regulate both its critical concentration for polymerization [Suprenant and Rebhun, 1983] and its calcium sensitivty, suggests that such regulatory molecules exist. These results suggest that sea urchin egg tubulin assembly in vivo could be controlled by variations in interacellular calcium levels acting in concert with urchin egg proteins similar in function to brain MAPs.
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    Masthead (1977)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 17 (1977) 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760170201
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    Molecular order and orientation in aromatic polyamide fibers by internal reflection spectroscopy and wide angle X-ray diffraction (1977)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 17 (1977), S. 93-95 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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 results of wide angle X-ray diffraction and, ATR polarization measurements are reported in order to characterize the anisotropy in poly(m-phenyleneisophthalamide) and poly(p-phenyleneterephthalamide) (Fiber B) fibers. Additional information on the state of order of the investigated fibers is derived from ATR spectroscopic accessibility measurements by deuterium exchange.
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    URL: http://dx.doi.org/10.1002/pen.760170206
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    The deep drawing of thermoplastics (1977)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 17 (1977), S. 101-110 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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 theory of deep drawing, which has been developed for metals, is examined critically for thermoplastics. Two special characteristics of thermoplastics, the strong orientation hardening after initial yielding and the ease of crack formation and growth, are shown to vitiate the usual correlation between the drawability of the sheet and the low strain plastic behavior of the material. Attempts to improve the limiting draw ratio of thermoplastics, by biaxially rolling sheet prior to forming, are shown to be effective only if the polymer does not craze easily under tensile stresses.
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    Azidosilane polymer - filler coupling agent (1977)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 17 (1977), S. 46-49 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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: This new coupling agent shows promise for use in reinforcing hydrocarbon type polymers, such as polyolefins and polystyrene, with glass fibers and inexpensive mineral fillers. Sulfonyl azide derivatives readily form durable bonds to many thermoplastics at normal extrusion and molding temperatures, without the use of peroxide or sulfur-type curing agents. Alkoxy silanes, attached to the sulfonyl azide, hydrolyze in the known manner forming bonds to inorganic fillers. Using commercial compounding and injection molding procedures, 40 wt percent of mineral fillers containing 1 percentofan azidosilane coupling agent were incorporated in polypropylene. Very substantial improvements in tensile, flexural and heat distortion properties were obtained with little loss in impact strength. An initial evaluation in a filled polystyrene showed significant, but less dramatic, improvements.
    Additional Material: 3 Tab.
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    URL: http://dx.doi.org/10.1002/pen.760170109
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    Solubility of supercritical gases in polymers - a review (1977)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 17 (1977), S. 65-72 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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: Processing of polymers is greatly affected by the presence of dissolved gases. Analysis of the effect of dissolved gases requires two types of information: equilibrium thermodynamic data and predictive correlations as well as diffusion rate data and analyses. We review here the state-of-the-art knowledge of the equilibrium thermodynamics of gases dissolved in polymers. The published data are presented and analyzed. Also, we review the latcst theories and predictive correlations for gas solubility in polymers.
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    URL: http://dx.doi.org/10.1002/pen.760170202
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    Polymeric adsorbents for treatment of waste effluents (1977)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 17 (1977), S. 58-62 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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 significant advance in ion exchange resin and adsorbent technology has been the development of the macroreticular pore structure. Synthetic rotes have been developed for preparing both ion exchange resins and polymeric adsorbents of high surface area and pore volume. Syntheses have been developed to the degree that the surface area and pore.parameters can be widely varied. Several of these macroreticular polymers based upon the crosslinked styrene and acrylate systems are now available commercially. These polymeric adsorbents are hard, durable, insoluble spheres of high surface area and porosity. They are available in a variety of polarities. The nonpolar adsorbents are particularly effective for adsorbing nonpolar solutes from polar solvents. Conversely, the polar adsorbents are very effective for adsorbing polar solutes from nonpolar solvents. Of particular interest is the use of these polymeric adsorbents for the treatment of effluent wastes. In some cases it has been demonstrated that one can recover significant quantities of re-usable chemicals that more than pay for the waste, treatment. The use of the polymeric adsorbents for the treatment of phenolicwastes is an example. Other related applications include the removal of chlorinated pesticides, TNT residues, and other noxious compounds from waste effluents and water supplies.
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    Transition behavior and phase segregation in TDI polyurethanesPresented part at the American Chemical Society Meeting. Philadelphia (1975). (1977)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 17 (1977), S. 73-80 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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: Prior studies of two series of segmented polyurethanes based on 2, 4 toluene cliisocyanate (2, 4 TDI) or 2, 8 TDI, butanediol, and a 1000 molecular weight polytetramethyleneoxide (PTMO-1000) soft segment revealed a rapid increase in soft segment glass transition temperature (Tg) with increasing urethane content in the 2, 4 TDI series. The change in Tg couldbe correlated with estimates of hard segment-soft segment phase mixing obtained by infrared analysis of the urethane NH and carbonyl bands. In the present paper, the infrared data have been reevaluated using improved procedures for resolving the carbonyl band into H-bonded and nonbonded components, and the relation between the estimated extent of phase mixing and Tg has been reexamined. The transition behavior in an extensive series of related polymers has also been determined, including 2, 4 TDI arid 2, 6 TDI samples with PTMO2000 as well as polybutyleneadipate (PBA-1000 and PBA-2000) soft segments. The results indicate the effectiveness, of increased soft segment molecular weight in promoting phase segregation, imply that much greater phase mixing occurs in polyester than polyether samples, suggest that anchoring the ends of the soft segments has only a small effect on Tg, and provide some evidence that H-bonding not only increases Tg but can also impede soft segment crystallization.
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    Distribution of some physical properties in injection-molded thermoplastic parts (1977)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 17 (1977), S. 96-100 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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: During the injection molding process, moldings undergo shear and elongational stresses. They are also exposed to thermal gradients of varying intensity. Invariably, molded parts, or at least some sections thereof, freeze before the polymer chains can relax to a random, non-oriented configuration. As a result, injection molded parts contain frozen strains and exhibit anisotropic physical properties. In the present work, a variety of experimental techniques have been employed to determine the three-dimensional variation of the following properties of injection-molded, thermoplastic, rectangular parts: density, heat shrinkage, birefringence, and tensile strength.
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    URL: http://dx.doi.org/10.1002/pen.760170207
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    Chemorheological changes in crosslinked epoxy resins subjected to large strains (1977)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 17 (1977), S. 85-92 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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: Chemorheological changes in epoxy resins subjected to large strains while heated were observed earlier, but the subject was not treated quantitatively. This paper describes the investigation of an epoxy resin - Epon 826, of known chemical, structure, crosslinked with two different amines. By means of a simple calibrated apparatus, the epoxide samples were subjected to large strains in a non-oxidizing atmosphere and in air. They were heated to different temperatures for various times; the results were compared with data obtained from unstrained samples kept in otherwise the same conditions. The results show a linear-logarithmic relation between the torsion modulus, G(10) and the time of applied strain at a certain temperature and also a linear relation between G(10), and 1/T°K, both above T(10). The results obtained in swelling experiments support the data from 10 sec torsional modulus vs temperature measurements. An increase in the amount of solubles and in Mc is observed on extending the time of heating. A clear difference in properties between the strained and unstrained samples, kept in otherwise the sane conditions, is observed and the contribution of the applied strain to chemorheology has been shown. Both systems of crosslinked Epon 826 showed the same general behavior, although the specific data were different.
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    Effect of olefin structure on the vapor-development of poly (olefin sulfones) under electron irradiation (1977)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 17 (1977), S. 269-273 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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 rate of vapor-development of poly(olefin sulfones) subjected to electron beam irradiation is markedly, dependent upon the olefin structure. At room temperature, poly(butene-1sulfone) and poly(cyclopentene sulfone) vapor-develop at rates several orders of magnitude lower than, for example, poly(2-methyl pentene-1 sulfone). Differences in vapor development rate for the various sulfones are shown to be related to differing rates of depolymerization which, in turn, are related to differences in ceiling temperatures for polymer formation. Kinetic analysis indicates that the mechanism involves random scission followed by depropagation and bimolecular termination.
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    Masthead (1977)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 17 (1977) 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760170401
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    Mechanical properties of mixtures of two compatible polymers (1977)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 17 (1977), S. 213-219 
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    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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 properties of mixtures of poly(2, 6-dimethyl p-phenylene oxide) and poly(styrene) have been measured by DSC, density gradient, dynamic mechanical response, and tensile testing. The mixtures are found to have single glass trasitions that vary continuously with the composition. They also have small negative excess volumes of mixing, indicative of strong polymerpolymer interaction. The dynamic mechanical response of the mixtures shows that the low temperature secondary relaxations are suppressed whereas those at high temperatures are enhanced. These observations imply that mixing on the segmental levc l has occurred. A plot of tensile strength vs composition at different strain rates reveals two regions of failure behavior. The high PS, high strain rate region is brittle, and the high PM2PO, low strain rate region is ductile. When the tensile yield data are treated according to the Ree-Eyring equation, the addition of PS to PM2PO is found to reduce the flow volum, e of the mixture. The overall effect on mechanical properties of adding small amounts of one component to the other is similar to that of anti-plasticization. Our experimental observations are consistent with the shifting of the relaxation mechanisms to longer times due to the negative excess volume of mixing.
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    Using the SI units (1977)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 17 (1977), S. 222-228 
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    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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: SI surpasses previous metric systems in coherence, simplicity, distinction between force and mass, choice of units, and uniformity of usage. Coherence eliminates conversion factors, other than powers of ten, within the system. Through simplification, only seven base units, two supplementary units, seventeen named derived units, and sixteen prefixes are needed to describe the entire system. Promotion of the newton as a unit of force and retention of the kilogram for mass clarifies the difference between the two quantities. New units are: pascal for pressure, siemens for electric conductance, and mole for amount of a substance. International agreement minimizes proliferation of specialized units or usage. Adopted conventions include spelling, abbreviations, style, and usage, as well as definitions for the units. Toleranceg, rounding of numbers, and elimination of the comma in multidigit numbers assume new significance. Conversion to SI offers a unique opportunity to reduce the number of sizes of many products. Several schemes for metric modularism have been developed for this purpose. In changing from conventional tip SI units, the key idea is “think metric” rather than use dual dimensioning.
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    Influence of molecular weight on fatigue behavior of polyethylene and polystyreneResearch Supported by Division of Materials Research, The National Science Foundation, Grant No DMR 74-02444 (1977)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 17 (1977), S. 246-250 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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: Fatigue tests in reversed tension-compression have been carried out on samples of polyethylene and polystyrene of widely varying molecular weights, extending up to 2, 000, 000. All tests on polystyrene specimens were made at 1600 rpm. For polyethylene, tests speeds had to be reduced to 100 rpm in order to avoid serious temperature effects. For both materials, increasing molecular weight leads to improved resistance to alternating loading. For polystyrene, this improvement in ultimate properties even continued well beyond molecular weight values where Tg, becomes effectively independent of molecular weight. For polyethylene, samples of high molecular weight did not fail even after 107 cycles of alternating loading at a stress level of 3000 psi.
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    Masthead (1977)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 17 (1977) 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760170601
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    The examination of poly(5-hexene-2-one sulfone) as a positive-working photoresist (1977)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 17 (1977), S. 350-352 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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 novel photoresist material is described, consisting of a copolymer of 5-hexene-2-one and SO2, which performs with or without the addition of sensitizers. This photoresist forms non-tacky films that adhere well to silicon oxide without requiring thermal treatment. They also have useful sensitivity, can be developed to form highly-resolved images, are inert to conventional etchants, and are readily removed after etching. The synthesis, characterization, and a possible mechanism for photodegradation are presented.
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    URL: http://dx.doi.org/10.1002/pen.760170603
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    A study of the photochemical reaction between poly(vinyl alcohol) and aqueous chromate ion (1977)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 17 (1977), S. 359-365 
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    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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 photochemical reaction between poly(vinyl alcohol) (PVA) and chromate ion in aqueous solution has been studied by ultraviolet spectroscopy and electron paramagnetic resonance (EPR). The first step of the reaction appears to be formation of a PVA-chromate ester. No further detectable chemical changes occur unless the ester is irradiated. Spectral sensitivity data indicate the reaction is initiated only by the chromate ester charge transfer absorptions at approximately 370 nm and 450 nm. EPR indicates an equilibrium concentration of Cr (V) during irradiation arid a decrease in concentration of Cr(V) following second order kinetics upon cessation of irradiation. The final reaction product is Cr (III) complexed with the hydroxyl groups of the PVA. The reaction rate is a function of pH between pH 12; however no detectable reaction occurred above pH 12. A mechanism is proposed for the PVA-chromate photoreaction in solution.
    Additional Material: 10 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760170606
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    Three dimensional behavior of negative electron resists (1977)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 17 (1977), S. 377-380 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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: It is illustrated experimentally that swelling and deformation of narrow lines (width 〈 1 μm) is an important limitation on the fidelity and transverse resolution of negative electron resists. The thickness response curve developed for negative resists is discussed and the effect of feature size is introduced through the experimental parameter DgR, the rigid gel dose, or the dose required to initiate a free standing line of width 〈 0.2 μm. The transition from line to area exposure is discussed and the effect of substrate backscatter or transverse resolution in gratings is calculated. The observed resolution is 3-5 times the calculated value from swelling and deformation during development.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760170609
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    Theoretical considerations on the sensitivities of electron beam resists (1977)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 17 (1977), S. 390-395 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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 theoretical study has been carried out in order to explain the sensitivities of electron beam and X-ray resists. A preliminary investigation reveals that the behavior of these resists, on irradiation by high energy radiation, may be considered to be the electronically-excited species in the polymer. To elucidate the chemical reactions in the excited states the adiabatic potential curves are calculated by the INDO/S procedure, which considers all the valence electrons and all the singly excited electronic configurations. Polyethylene and polyisobutylene were chosen as representative of crosslinkable and degradable polymers, respectively, since there is a parallelism between the beam sensitivity of resists and the effects of high energy radiation on polymers. Polyisobutylene has many antibonding curves favorable for the main chain scission in the excited states and polyethylene does not except for one improbable state. It was concluded that degradability is explainable by the ease of bond fission in the excited states; the crosslinkability is considered to be nondegradable property.
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    Graft copolymers of polysaccharides with thermoplastic polymers. A new type of filled plastic (1977)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 17 (1977), S. 311-316 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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 series of starch graft copolymers and one cellulose graft copolymer were prepared containing 40-50 percent synthetic polymer. The monomers used (styrene, methyl methacrylate, methyl acrylate, and butyl acrylate) were chosen to give grafted synthetic polymers with varying glass transition temperatures (Tg). These graft copolymers were extruded, in the absence of any added thermoplastic homopolymer, to give strong, continuous polysaccharide-filled plastics which are biodegradable and which exhibit little or no die swell. Properties of plastics varied with the Tg of the thermoplastic portion. Starch-g-polystyrene and starch-g-poly(methyl methacrylate) were hard and brittle, while graft copolymers prepared from methyl and butyl acrylate were more flexible and leathery. The graft Uopolymers with lower Tg grafts required less torque and could be extruded at lower temperatures. In the methyl acrylate series, a graft copolymer prepared from gelatinized starch was more easily extruded than one prepared from granular starch, and addition of water produced a water-filled extrudate of excellent quality. The surprising feature of these results is that the matrix polymers, starch and cellulose, are rigid, nonsoftening materials. Grafting of a thermoplastic polymer to these matrix polymers would not be expected to give an extrudable product. The results are explained as powder flow followed by fusion or sintering of the graft polymers under the temperature and pressure conditions in the die.
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    URL: http://dx.doi.org/10.1002/pen.760170508
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    Polyketones and polysulfones for conservation of ethylene polymers (1977)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 17 (1977), S. 335-339 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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: Because of the increase in cost of foreign oil, ethylene costs have increased markedly within the last several years. There is presently a sizeable incentive to reduce raw material costs for basic polymer manufacture. The polyketones, synthesized from ethylene and CO, and the polysulfones, synthesized from ethylene and SO2, both utilizing high energy radiation, offer one such possibility. The process has the additional advantage that CO and SO2, usually considered as.wastes and pollutants from fossil fuel burning power plants, are converted to useful materials. The polyketones and polysulfones formed by radiation-induced polymerization from the gas phase below 100°C have been found to be high molecular weight polymers which, depending on composition, either melt with difficulty or decompose at temperatures of 250°C or higher. The higher temperature (〉100°C) catalyst-induced reaction produces low molecular weight waxes. Design calculations indicate that for a G value of 10, 000 and 50 percent energy deposition efficiency, it would take 331 megacuries of Co6O to conserve 2 billion pounds of ethylene or 25 percent of the overall U.S. consumption in the PE market by substituting CO and SO2. This savings amounts to as much as $280 million at today's market price. Electron machine radiation with a 25 percent energy deposition efficiency requires a total beam power of 9800 KW. The use of machine radiation is preferred because of safety, availability, and lower initial investment. The challenge presented by the development of these substituted polymer systems depends on (1) the determination of the uniqueness of the radiation process and confirming the yields with electron machine radiation, (2) the processability and market acceptability of the substituted polymers, and (3) the ability to design an efficient radiation process reactor.
    Additional Material: 1 Ill.
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    Peel mechanics of adhesive joints (1977)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 17 (1977), S. 462-466 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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 review is given of the mechanics of peeling rupture of an adhesive joint, consisting of a flexible adhering strip peled away from a layer of adhesive. Attention is drawn to a number of anomalous results that cannot be accounted for solely, in terms of the thermodynamic work of formation of two new surfaces. The work of detachment is found to be generally much larger than the theoretically-predicted amount. Moreover, the value obtained is greater for thicker layers of adhesive, and for detachment at a peel angle of 180° rather than at 90°. Also, it is found to increase with increasing thickness of the adhering strip, passing through a maximum value in some cases and then decreasing as the strip thickness is increased still further. All of these effects are attributed to dissipative processes, for example, plastic yielding, in one or both of the adhering layers as they are peeled apart. Some quantitative relationships are given for the additional peel forces arising from plastic yielding of the adherend or the adhesive.
    Additional Material: 4 Ill.
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    Interfacial (polymer-substrate) failure of ultraviolet radiation curable coatings (1977)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 17 (1977), S. 478-483 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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 development of ultraviolet radiation technology to cure or photopolymerize acrylic unsaturated monomers, oligomers, and polymers into tight network structures introduces several adhesion problems that can be related to or associated with interfacial polymer-substrate failure. This paper discusses network formation, polymer-interfacial growth association and failure as a function of the following variables: light intensity (effect on sol/gel conversion), photoinitiator (structurereactivity as a function of conversion), polymer shrinkage, and substrate wetting. The results of this study show that all of the above variables interact in a composite fashion to influence the final properties of the ultraviolet cured coatings.
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    X-ray lithography (1977)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 17 (1977), S. 385-389 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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 advent of X-ray lithography as a natural compliment to electron beam pattern generation and photolithography seems to be filling a need in the fabrication of submicron devices. The X-ray technique, which is simple for single level devices, lags behind other lithographies in registration techniques. However, its proven high resolution capabilities is responsible for the increased interest in further development. At present a, variety of mask substrates are being evaluated with no one material exhibiting an overwhelming advantage. The type of substrate used is closely coupled to the permissable wavelength of the X-ray source. The X-rays used for lithography to date vary from Rh L (4Å) up to CK (44Å). Each wavelength shows a distinct advantage and disadvantage. For example, at short wavelengths substrates can be relatively massive but resists are less sensitive and high resolution masks have low contrasts. At longer wavelengths, resists are more sensitive and masks have higher contrast, but defects due to dust are more probable. The use of more than one X-ray source could fulfill the requirements imposed by mask making and device fabrication. High throughput for both masks and device require both foster resists and higher intensity X-ray sources.
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    Parameters, affecting the sensitivity of poly(methyl methacrylate) as a positive lithographic resistA detailed paper on this subject will appear in the IBM J. Res. Dev., 21, (2)(1977) (1977)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 17 (1977), S. 396-401 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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 contribution of parameters such as molecular weight, molecular weight distribution and stereochemistry to electron beam sensitivity of poly(methyl methacrylate), PMMA, has been investigated. The sensitivity is interpreted here as the minimum radiation dose required to obtain a predetermined solubility rate ratio, S/So = SR, of the exposed, S, and unexposed, So, material. The G-value was foam be independent of molecular weight, molecular weight distribution, and stereochemistry. Data indicate that the weight average molecular weight ratio correlates better with SR than the number average molecular weight ratio. The tacticity of the resist and the developer solvent molecular weight or size have a large effect on solubility rate. Although the solubility rate pf isotactic PMMA is much greater than the syndiotactic and heterotactic stereoforms, the sensitivity appears to be independent of tacticity. In a homologous series of n-alkyl acetate developer solvents, the molecular size of the solvent has a greater effect on the solubility rate than the molecular weight of the resist. A developer solvent has been selected from the n-alkyl acetates which enhanced the sensitivity of PMMA.
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    Differential dissolution and electron-beam lithographic sensitivity of poly(methyl methacrylate) (1977)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 17 (1977), S. 414-419 
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    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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: Photolithographic and electron-beam integrated circuit fabrication techniques rely heavily upon differences in polymer resist dissolution (development) rates to produce circuit patterns. We have applied the wide-line NMR, technique, augmented by dynamic nuclear polarization, to the measurement of polymer dissolution rates of poly(methyl methacrylate), (PMMA). At high gamma-ray exposures, we find PMMA to have dissolution rates from 2X to 1000X those of unirradiated material. The highest radiation-enhanced dissolution rates are obtained with carbon tetrachloride-based developer solutions, whereas generally lower enhanced rates are observed with 1:3 acetone or methylethylketone/isopropanol standard developer. E-beam line exposures are developed in PMMA and poly(ethyl methacrylate), PEMA, resists using similar developers for comparison. Using straight CCl4 as a developer, e-beam lines 1-2 μ wide were developed in 3800 Å thick PEMA resist at 1 × 10-5 C/cm2 with ≤200 Å loss in unexposed resist thickness. The higher differential dissolution with CCl4, a poorer solvent for unirradiated PMMA than acetone or MEK, is explained by decline in polarity of PMMA by radiationinduced decarboxylation.
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    Limiting surface tension by gas chromatography (1977)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 17 (1977), S. 434-435 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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 change in retention mechanism at the glass transition temperature (Tg) of a polymer stationary phase from surface adsorption below Tg to bulk sorption above Tg allows for a separate determination of the magnitude of the solute interaction with both the bulk and the surface of the polymer. As a result, the limiting surface tension of the polymer-probe solution can be obtained from the corresponding partition coefficients. Examples of such determinations are given for several polymer-solute systems.
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    Oligomeric fluorinated additives as surface modifiers for solid polymers (1977)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 17 (1977), S. 450-455 
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    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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: Successful modification of the surface properties of solid polymers was obtained by the adsorption of appropriate partially fluorinated oligomers at polymer/air and polymer/substrate inter faces during the formation of these interfaces. These additives, in concentrations of 0.25 percent, effectively lowered the critical surface tension of wetting, γc, of such polymers as polystyrene, poly(methylmethacrylate), and poly(vinylidene chloride) copolymers by as much as 26 dyn/cm. The obtained low γc values of 14 dyn/cm correspond to surfaces containing closely packed CF3 and CF2 groups. Adhesion of additive-containing polymer films to various substrates was demonstrated to be a function of additive diffusion to the polymer/substrate interface, its subsequent adsorption and molecular orientation at that interface, and the surface energy of the substrate. The fluorinated additive molecules also have the advantage of being sufficiently mobile in the solidified polymer to reach and repair the interfaces.
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    Masthead (1977)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 17 (1977) 
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    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760170801
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    Studies of methyl methacrylate-methyl α-chloroacrylate, copolymers and poly(methyl α-chloroactylate) as electron sensitive positive resists (1977)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 17 (1977), S. 402-405 
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    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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: Poly(methyl α-chloroacrylate) (PMCA) and the copolymers of methyl methacrylate and methyl α-chloroacrylate (poly(MMA-co-MCA)) have been reported recently to be more susceptible to radiation degradation than poly(methyl methacrylate) (PMMA). In this paper we report our studies of PMCA and poly(MMA-co-MCA) as electron-sensitive positive resists. It has been found that both PMCA and the copolymers are more sensitive than PMMA. Using mixtures of dimethylformamide and 2-propanol as developers, the sensitivities of PMCA and poly(MMA-co-MCA) (38 mole percent MCA) have been found to be 1 × 10-5 and 6 × 10-6 coulomb/cm2, respectively. It has also been found that crosslinking predominates in PMCA when the electron dose exceeds 6 × 10-4 coulomb/cm2.
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    Thermally-reacted poly(methacrylamide) as a positive electron beam resist (1977)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 17 (1977), S. 410-413 
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    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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-reacted poly(methacrylamide) degrades under high-energy irradiation. It has a sensitivity of 2-3 × 10-7 C/cm2 when exposed to 10 KV electrons. The resist is thermally stable to 330°C and has a high glass transition temperature, 180 200°C. It may be used for the lift-off process and ion-milling.
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    Introductory remarks (1977)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 17 (1977), S. 433-433 
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    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760170702
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    Interfacial phenomena between brittle and polymeric films (1977)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 17 (1977), S. 436-439 
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    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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: An ovrerview of a new theory for describing interfacial phenomena in layered composites is presented. Relations are given for determining the adhesion of thin brittle films on flexible substrates, for determining residual strains resulting from drying solvent cast films, and for calculating thermoelastic strains in unsymmetric laminates. An experimental technique to measure the adhesion is discussed and values are obtained using experimental data. Residual strains are also calculated using the derived relations and solvent d in data.
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    Adhesion at polypropylene-cellophane interfaces (1977)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 17 (1977), S. 456-461 
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    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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 shear strength of bonds between isotactic polypropylene and cellophane, formed under standard conditions, has beer studied as a function of cooling rates, following bond formation, and after ageing at temperatures up to 90°C. Rapid cooling produced cohesively failing bonds with shear strengths above 20 kg/em2. Weak, adhesively failing joints were produced under slow-cooling conditions. Strong bonds deteriorated when joints were aged at temperatures above 50°C, but further improvement in bond strength was observed upon ageing at lower temperatures. Experimental observations were consistent with the development of smectic structure in the polypropylene upon rapid cooling; a tendency for transcrystallization in slow-cooled joints was offset by the presence of weak boundary layers in the interface. Ageing produced further development of weak boundary layers and a transition from smectic to monoclinic crystallization in polypropylene. At higher ageing temperatures, the former effect seemed dominant; at lower temperatures, the structural change was assumed responsible for the observed improvement in bond strength.
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    Adhesion effects and performance of mass transfer equipment using teflon surfaces (1977)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 17 (1977), S. 484-493 
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    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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: Contact angle data are reported for a number of pure and binary liquids residing on a polytetrafluoroethylene (PTFE) surface, measured under conditions simulating distillation, condensation or absorption. By comparing the wettability of such systems with the performance obtained under the same conditions for equipment employing PTFE heat or mass transfer surfaces, it is demonstrated that liquid-solid adhesion plays a key role in determining the heat or mass transfer rates. It is further shown for a considerable number of industriallyimportant conditions that PTFE can give enhanced equipment performance over that obtained, using conventional high energy solid materials.
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    Structure and properties of microcomposites and macrocomposites from block polymers (1977)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 17 (1977), S. 498-505 
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    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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 incorporation of a rubber phase in glassy polymers, as is well known in the case of high impact polystyrene, leads-to an increase in their impact strength. Block polymers offer three principal approaches for obtaining multiphase glassy polymers in which an elastorner phase is present in the matrix of the glassy polymer. They are: (1) control ofblock polymer composition, (2) blending of block polymer with homopolymers, and (3) polymerization of a solution.of a block polymer in the monomer corresponding to one of the blocks. The observed properties, such as impact strength, modulus, and heat distortion temperature, desired in rubber modified glassy polymers are discussed for block polymer systems prepared using the above approaches.
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    Structure of AB block copolymers with a polypeptide block: Effect of the chain conformation (1977)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 17 (1977), S. 523-526 
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    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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 structure of AB copolymers with a polypeptide block has been studied by X-ray diffraction, electron microscopy, infrared spectroscopy, and circular dichroism. Copolymers with a polyvinyl block (polybutadiene or polystyrene) and a hydrophobic polypeptide block (polybenzyl-L-glutamate or polycarbobenzoxy-L-lysine) exhibit a lamellar structure in the dry state and in solution in dioxane or in different chlorinated solvents. This lamellar structure consists of plane, parallel, equidistant sheets. Each sheet results from the superposition of two layers: one formed by the polyvinyl chains in amore or less random coil conformation, the other formed by the polypeptide chains in an α-helix conformation, arranged in a hexagonal array and generally folded. Copolymers with a polyvinyl block and a hydrophilic polypeptide block (poly-Llysine or poly-L-glutamic acid) exhibit a larnellar structure in water solution and in the dry state. The difference between this lamellar structure and the preceding one consists in the conformation of the polypeptide chains: an intramolecular mixture of coiled chains, α-helices, and β chains. Copolymers with a polysaccharide block and a hydrophobic polypeptide block exhibit in DMSO solution and in the dry state a lamellar structure similar to that of copolymers with a polyvinyl block and a hydrophobic polypeptide block.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760170807
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    Viscoelastic properties of homogeneous block copolymers (1977)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 17 (1977), S. 560-562 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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 molecular theory of Rouse-Bueche-Zimm has been modified to predict the viscoelastic behavior of homogeneous block copolymers. The model consists of beads and springs whose magnitudes correspond to the types of blocks in the polymer. Maximum relaxation times can be computed by this model. Viscoelastic data for poly(styrene-b-α-methyl styrene-b-styrene), poly(α-methyl styrene-b-styrene-b-α-methylstyrene) and poly(styrene-b-α-methyl styrene) were determined by stress relaxation methods. The results compare favorably with those predicted by the theory.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760170811
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    Statistical thermodynamics of microdomain structures in block copolymer systems (1977)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 17 (1977), S. 582-586 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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 statistical thermodynamic theory of the microdomain structure of block copolymers is presented in qualitative physical terms. Special emphasis is placed on a presentation of the final algebraic formula which may be used to determine lamellar domain sizes as a function of block length and physical parameters. Calculations on lamellar domains and preliminary results for spherical domains are compared with experiments. Other topics discussed are: width of the interphases, results of a more exact theory, and thermodynamic., stability of the domain structure.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760170815
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    Masthead (1977)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 17 (1977) 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760170901
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    Glass bead-filled polypropylene part I: Rheological and mechanical propertiesPresented in part at the 34th ANTEC Soc. Plastics Eng., April 26-29, 1976, Atlantic City, N. J. (1977)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 17 (1977), S. 657-665 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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: Five glass bead-filled polypropylene composites were rheologically characterized at 240°C using two rotational rheometers to obtain low shear-rate data and a capillary rheometer to obtain high shear-rate data. Both steady and dynamic properties were measured at low shear rates. Each composite was also injection molded into tensile and flexural test bars for a mechanical properties profile at 25°C. The tensile modulus was determined from a simple extensional deformation whereas the flexural modulus was determined from a three-point-bend test.The relative shear viscosity and relative loss modulus are different nonlinear functions of the volume fraction of beads at a constant shear rate, while the relative storage modulus appears to be a linear function of bead fraction. The relative viscosity decreases with increasing shear rate and the zero shear-rate data are in very good agreement with the Guth-Gold equation.The relative tensile modulus and relative flexural modulus are each linear functions of bead fraction over the entire range of filler concentration, 0-29 vol percent. From these data it is concluded that a simple correspondence between slow viscous flow and small strain elasticity does not exist for these composites.
    Additional Material: 11 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760170902
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    A study of the effect of pressure, time, and temperature on high-pressure powder molding (1977)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 17 (1977), S. 691-699 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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: High pressure room temperature molding of polymeric powders has been found to be a useful technique for producing parts from certain hard-to-process polymers and certain common polymers. Polymeric powders of less than 175μ were compacted at pressures up to 0.689 GPa. Subsequent heat treating of the compacted samples improves the mechanical properties of the samples to levels comparable to those attained by other techniques. Thermosetting or reactive polymers which do not evolve vapors during curing are readily processed by this technique. Semicrystalline polymers which are molded above their Tg are also easily processed by this method. Glassy polymers, in general, have not been found to be processable. The important process variables are molding pressure, molding time and heat treating temperature and time. The process relies on particle-to-particle fusion by either chemical reaction or localized melt fusion. For semicrystalline polymers, the annealing temperature is within the melting endotherm. Reactive polymers cure at their optimum curing temperature.
    Additional Material: 19 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760170907
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    Injection molding in disk-shaped cavitiesPresented in part at the 1976 ANTEC meeting under the title “An Experimental Study and Simulation of Disk Filling by Injection Molding.” (1977)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 17 (1977), S. 706-710 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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: Experimental results together with predictions based on a numerical simulation are reported for the filling by injection molding of a center gated, disk-shaped cavity with acrylonitrile-butadiene-styrene terpolymer (Lustran ABS Q714) and with polypropylene (Pro-fax 6523). At a specified fractional fill, the output of a pressure transducer (Δπzz) near the sprue was measured and the clamp force (F) was obtained by. integrating the output of four pressure transducers over the projected area. A systematic study was made to determine the effect of the (1) material properties, (2) cavity thickness, (3) melt temperature in the barrel, and (4) injection rate on the measured and simulated values for the pressure transducer output and clamp force. For a given barrel temperature, cavity thickness and intermediate-to-high injection rates, the pressure transducer output and clamp force were found to be nearly independent of injection rate for ABS and to increase with increasing injection rate for polypropylene. As the injection rate approached zero, the pressure transducer output and clamp force increased because of the long time available for cooling the flowing melt. For ABS the simulated results were about 5-25 percent higher than experiment, whereas for polypropylene they were about 10 percent lower than experiment when the viscosity model included solidification Flow instabilities were observed to occur at conditions where the pressure transducer output curve showed a marked upturn with decreasing injection rate.
    Additional Material: 8 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760170909
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    Effects of coupling agents on the mechanical and rheologica properties and mica-reinforced polypropyleneBased on the Master of Applied Science thesis of M. S. Boaira. (1977)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 17 (1977), S. 715-718 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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: Dimethylaminoethyl methacrylate (DMAEMA) was investigated as a prospective coupling agent for mica-reinforced polypropylene. Composites prepared with the widely-used silane coupling agent, N-(4-vinylphenyl) methyl-N′-(3-trimethoxysilylpropyl)ethylenediamine monohydroehloride (Z-6032), were compared with the amino-coupled composite. Improvements in the flexural properties at room temperature were observed with the two coupling agents: a 22 percent increase in the strength with the silane compared to a. 16 percent increase with DMAEMA. Cone-and-plate viscometry at 220°C showed that the addition of coupling agents greatly, reduces the viscosity of the composite: a 50 percent decease was obtained with the silane-treated composite and a 20 percent decrease with DMAEMA.
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    URL: http://dx.doi.org/10.1002/pen.760171003
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    Effects of post-curing of unsaturated polyester resins in various media (1977)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 17 (1977), S. 775-781 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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: Experimental studies were performed on the effects of postcuring of' styrenated, unsaturated polyesters in nitrogen gas, water or its vapor, hexane vapor, dimethyl sulfoxide (DMSO), and dirnethyl formamide (DMF) all at 100°C It was found that, nitrogen gas and water are inactive, hexane acts as a chain transfer agent, and DMF and DMSO behave as solvents which extract residual styrene monomer and anhydrides from the resins. Post-treatment in inert media can result in further reaction leading to more complete cure as free radicals and residual monomer continue to react. The post-curing reaction is a radical copolymerization. Further condepgation polymerisation does not occur. Post-curing in, hexane vapor1eads to a transfer of the active sites from the radicals to the hexane and to no further radical polymerization.
    Additional Material: 15 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760171103
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    Swelling and hygroelasticiiy of polymeric composites (1977)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 17 (1977), S. 799-802 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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: Investigated are the swelling and hygroelasticity of a unidirectional glass fiber-reinforced epoxy composite subjected to boiling water for 24 hrs. By analogy with thermoelasticity, a coefficient of hygroelasticity is defined and shown to be predictable from the coefficients of the constituent materials by Schapery's equations. A mechanism for water penetration into the composite which combines capillarity and diffusion is proposed on the basis of the results of the water take-up as a function of the composite specimen width (fiber length).
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760171107
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    Effect of cross-linking on hydrostatic creep of epoxy (1977)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 17 (1977), S. 837-841 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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: Samples of epoxy having three different degrees of crosslinking were subjected to several constant values of hydrostatic pressure ranging from 1000 psi to 80 ksi. Each period of constant pressure was followed by a period at atmospheric pressure. A continuing decrease in volume (creep), as measured by axial strain at constant pressure, was observed for pressures of 10 ksi and greater. The creep strain was recovered immediately upon pressure removal. Reapplication of pressure after a short period at atmospheric pressure resulted in the same creep behavior as that resulting from the first pressure. The least cross-linked epoxy had the smallest creep rate and the smallest compressibility. These observations are consistent with the view that the leapt cross-linked epoxy would be the most compact and have the least voids at points of cross-linking.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760171205
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    The properties of mica-filled polypropylenes (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 169-174 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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: Water-ground Phlogopite micas were classified into narrow particle-size distributions containing flakes with well-defined diameters and thicknesses in order to evaluate the influence of particle size and flake aspect ratio on the mechanical properties of mica-filled polypropylenes, For the purposes of comparison, most of the injection-molded specimens contained 40 percent (by weight) mica. As expected, the flexural and tensile modulus values increased in proportion to the aspect ratio over the range from 30 to 60 to a maximum of 8 GPa. The measured tensile strengths of the mica-filled polypropylenes increased substantially as the flake diameter became smaller, but did not correlate with the flake aspect ratio. The attainable properties were frequently dependent upon the method of mixing, and considerable care was necessary to ensure proper dispersion and adequate coupling. Intensive mixing, as in a Gelimat Mixer, may cause in situ delamination and particle-size reduction of the mica filler particles, leading to a marked increase in tensile strength of the resulting composite. The mica-filled compounds could be reprocessed many times without significant loss of properties, particularly compounds having mica particles less than 40 μm in diameter. The fracture energies (notched Izod) and the heat-distortion temperatures were not appreciably influenced by the size or aspect ratios of the mica within this range. Increased fracture toughness could be achieved by reducing the mica concentration or employing a polypropylene copolymer. Guidelines are presented to indicate the preferred characteristics of mica fillers and the influence of mixing conditions on performance.
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    URL: http://dx.doi.org/10.1002/pen.760240303
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    Modeling of polyethylene terephthalate reactors: 7. MWD considerations (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 30-41 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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 mathematical model has been developed to compute the molecular weight distribution (MWD) in the polyethylene terephthalate (PET) manufacturing process. Unlike the previous efforts, this model takes into account the influence of side reactions and various interchange reactions on MWD. The process of blending of molten polyester chips has also been simulated with a view to calculate the equilibrium MWD as well as the time required to reach the equilibrium MWD. The1 significance of the results has been discussed in terms of industrial operations involving PET polymerization and PET blending.
    Additional Material: 10 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760240104
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    The form and origin of some non-equilibrium morphologies in multicomponent polymer blends-a brief report (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 541-543 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760240806
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    Interactions in polymer blends-relationship between thermodynamic and scattering measurements (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 555-562 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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 of preparation and of determining miscibility limits for partially miscible binary polymer blends are described. An equation-of-state, theoretical description of this behavior is introduced and the terms describing interactions within the system discussed, Values of these interaction terms are obtained by fitting the models to measured cloud point curves, heats of mixing data, etc. The use of neutron scattering experiments to obtain molecular conformation and interaction parameters is described and a comparison made with values extracted from the thermodynamic measurements.
    Additional Material: 9 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760240808
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    Water-soluble copolymers VIII. Synthesis and dilute solution rheological studies of dextran-g-poly(acrylamide-co-sodium acrylates) (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 163-168 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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: Dextran-g-poly(acrylamide-co-sodium acrylates) were prepared by partial hydrolysis of dextran-g-poly(acrylamides) with controlled numbers and lengths of grafted chains. This hydrolysis route proved to be more effective than Ce(IV)-induced cografting of acrylamide and sodium acrylate comonomers onto dextran in producing the desired graft-copolymer structures. The resulting copolymers were characterized and the effects of composition, temperature, ionic strength, and shear rate on dilute solution rheological properties were studied.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760240302
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    Solution of final stages of polyethylene terephthalate reactors using orthogonal collocation technique (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 194-204 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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 formation of polyethylene terephthalate (PET) has been modeled to have reactions with monofunctional compounds, redistribution, and cyclization reactions in addition to the usual polycondensation step. In the final stages, the overall polymerization is mass-transfer controlled and solution of the reactor performance equations have been determined through the orthogonal collocation technique. This technique is found to be considerably more efficient for PET reactors compared to the finite difference method; the use of ten collocation points gives results which are close to the exact solution.
    Additional Material: 11 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760240306
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    Theoretical investigations on some rigid-rod polymers used as high-performance materials (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 218-225 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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: This review focuses on a new type of para-catenated aromatic polymer being used in the preparation of high-performance films and fibers of exceptional strength, thermal stability, and environmental resistance, including inertness to essentially all common solvents. Polymers of this type include cis and transpoly(p-phenylene benzobisoxazole) (PBO), and the cis and trans forms of the corresponding poly(p-phenylene benzobis-thiazole)(PBT). The purpose of this paper is to summarize the authors' theoretical work on the structures, conformational energies, intermolecular interactions, and electronic properties of PBO and PBT chains, including the protonated forms known to exist in strong acids. The emphasis is on how such studies provide a molecular understanding of the unusual properties and processing characteristics of this new class of materials.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760240309
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    Poly(p-phenylene terephthalamide) films formed from extrusion and coagulation of liquid crystalline sulphuric acid solutions: Characterization of orientation and void structure, annealing, and upgrading of film mechanical properties (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 242-251 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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: Poly(p-phenylene terephthalamide) (PPD-T) films have been prepared by continuous extrusion of liquid crystalline 17 percent PPD-T/sulphuric acid solutions through an annular die followed by coagulation, Films extruded without drawdown exhibit some polymer chain orientation in the machine direction. This is increased by uniaxially drawing down films. Films produced with a lubricated conical mandrel sitting between the die and the coagulation bath exhibit an equal biaxial orientation. The uniaxially oriented films exhibit highly anisotropic mechanical properties, while the mandrel-produced film exhibits balanced properties. Heat treatment at 350°C results in significant enhancement of the tensile strength of the mandrel film. Void structures in the films have been investigated by mass density, scanning electron microscopy (SEM), and small-angle X-ray scattering (SAXS). Density measurement indicate a void content decreasing with decreasing film thickness and heat treatment. SEM locates micron-size voids in the thickest films, apparently caused by rapid coagulation. SAXS indicates much smaller void sixes which are roughly prolate ellipsoids (long axis in machine direction) for uniaxial films and oblate ellipsoids (short axis in thickness direction) for the mandrel produced films. Various techniques are used to estimate mean void size.
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    URL: http://dx.doi.org/10.1002/pen.760240403
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