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  • Physics  (48)
  • Cell & Developmental Biology
  • 1980-1984
  • 1975-1979  (66)
  • 1960-1964
  • 1950-1954
  • 1975  (66)
  • 1971
  • 1
    Electronic Resource
    Electronic Resource
    Nuclear spin relaxation in poly(diethylsiloxane) (1975)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 1269-1274 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Earlier work showed that heating causes poly(diethylsiloxane) to undergo a first-order transition from a semicrystalline solid to a more mobile viscous - crystalline material. The latter is composed of two phases and analogies between polymer and liquid crystal morphology and behavior have been made. The viscous - crystalline phase in PDES appears to be unique since the literature is devoid of other documented examples. In this study, spin - lattice and spin - spin relaxation times were measured over a wide temperature range. They show a glass transition at 138°K, a crystal - crystal transition at 206°K, and a transition around 250°K which results from translational motion of the polymer chains with respect to each other. This motion is observed in the amorphous phase at a lower temperature than in the crystalline phase. Translational motion in the crystalline phase is observed on melting of the crystallites. The spin - spin data permitted monitoring of the molecular motions in each phase and the data suggest that these phases exert some influence on the molecular motions of each other. The viscous - crystalline phase in PDES may represent a unique model for studying and understanding “precrystalline” behavior and structure in amorphous solids.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1975.180130701
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  • 2
    Electronic Resource
    Electronic Resource
    Driving force for hydraulic and pervaporative transport in homogeneous membranes (1975)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 1201-1214 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Experiments were designed to demonstrate that the chemical potential gradient required for liquid transport through swollen network polymer membranes manifests itself as a concentration gradient and that the rate of transport is independent of how this gradient is established. The fluxes of various liquids through a crosslinked rubber membrane were measured in hydraulic and pervaporation modes of permeation. The pressure applied downstream in the latter act simply to fix the activity of the liquid in the downstream membrane surface. The experiments show the flux is a unique function of this activity, and it does not matter how it is established. Sorption data were used to convert these results into a plot of flux versus concentration differential across the membrane which was analyzed by Fick's law using a model for the concentration dependence of the diffusion coefficient. Measured ceiling fluxes for pervaporation for a number of liquids were found to be the same as those estimated from hydraulic permeation data. A simple mathematical representation for an ideal system is used as a pedagogical device to demonstrate the conclusions.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1975.180130612
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  • 3
    Electronic Resource
    Electronic Resource
    The elongation and time dependence of the crystallinity of low-density polyethylene (1975)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 1945-1957 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: It has been presumed in studies of the orientation of low-density polyethylene and its time dependence that the degree of crystallinity remained constant with elongation and did not vary with time following elongation. This paper represents a test of this hypothesis by several methods. The change in crystallinity accompanying stretching has been followed by a modification of an x-ray method for uniaxial orientation proposed by Ruland in which diffraction peaks are resolved into crystalline and amorphous components and their respective areas are determined by two-dimensional integration over both the Bragg angle and the azimuthal angle of diffraction. The weight-fraction crystallinity is then determined from the ratio of the weighted crystalline area to the total area. There appears to be no significant variation in crystallinity up to 50% sample elongation for both slowly and rapidly stretched samples at room temperature. The dynamic crystallinity change accompanying small amplitude vibration has also been determined by the dynamic x-ray diffraction technique and found to be negligible over a wide range of frequency. The degree of crystallinity has also been evaluated from the absolute infrared absorbance of crystallinity-sensitive bands and has also been found to be independent of elongation at room temperature up to 80% elongation. Changes have also been observed by this method during relaxation at constant length following rapid extension and have also been found to be negligible. These results also indicate negligible changes in rotational isomer population. Consequently, we conclude that changes observed during relaxation and vibration arise from orientational changes rather than changes in the degree of crystallinity.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1975.180131009
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  • 4
    Electronic Resource
    Electronic Resource
    Dielectric study of relaxations and polymorphism in poly(diethyl siloxane) (1975)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 977-983 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The dielectric behavior of poly(diethyl siloxane) supports the adiabatic calorimetric findings of Beatty and Karasz. In particular, a sub-Tg transition is observed near -180°C at 100 Hz, the glass transition near -135°C at 100 Hz, and a first-order transition near -70°C (crystal-crystal transformation). This glass-transition temperature is the lowest reported polymeric glass transition for polymers.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1975.180130510
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  • 5
    Electronic Resource
    Electronic Resource
    13C NMR of polybutadienes (1975)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 13 (1975), S. 1963-1967 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1975.170130822
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  • 6
    Electronic Resource
    Electronic Resource
    Preparation of films exhibiting a balanced temperature dependence to permeation by aqueous solutions - a study of lower consolute behavior (1975)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 13 (1975), S. 2551-2570 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Temperature dependence of solute transport through aqueously swollen polymeric films and membranes can be altered to show even apparent negative activation energies by the use of polymers exhibiting a lower consolute behavior in solution. The principles by which we constructed a host of such polymers are discussed. A solubility rule is presented which predicts that solutes in water will show a lower critical solution temperature if the proper hydrophilic-hydrophobic balance is achieved.
    Additional Material: 19 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1975.170131113
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  • 7
    Electronic Resource
    Electronic Resource
    Neurosecretory system of the American dog tick, Dermacentor variabilis (Acari: Ixodidae). II. Distribution of secretory cell types, axonal pathways and putative neurohemal-neuroendocrine associations; comparative histological and anatomical implicationsIn part, from a dissertation by the senior author submitted in partial fulfillment of requirements for the Ph. D. degree in Entomology, The Ohio State University, Columbus. Supported by NIH Training Grant 5 T01 AI 00216 through the Acarology Laboratory, The Ohio State University.Supported in part by Public Health Service Research Grant AI-09556 from the National Institute of Allergy and Infectious Diseases (Principal Investigator, J. H. Oliver, Jr). (1975)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 145 (1975), S. 269-293 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Histological observations using specialized techniques reveal neurosecretory cells in 18 centers throughout the rind (cortex) of the central nerve mass or synganglion of Dermacentor variabilis. Many cells contribute to complicated networks of neurosecretory pathways and tracts in pre- and post-esophageal portions of the synganglion. The four types of neurohemal-neuroendocrine associations found in Dermacentor resemble structures found in soft ticks (Argasidae) and in other Arachnida, but are more diverse than those described from any other single species. Neurosecretory terminals are distributed diffusely and in two concentrated associations within the perineurium of the synganglion and major peripheral nerves. Terminals are also distributed in the perineurial layers of lateral segmental organs which lie in the general hemocoel at the level of the pedal nerves. A retrocerebral organ complex surrounds the esophagus at its junction with the midgut. The complex includes dorsal and ventro-lateral lobes (containing neurosecretory terminals and intrinsic secretory cells) and the proventricular (neurohemal) plexus. This plexus seems to be a modified (concentrated) cardioglial association. Cardioglial associations are also formed by the neurosecretory innervation of vascular walls of the dorsal aorta and circulatory sinuses which envelope the synganglion and major peripheral nerves. Inferential considerations of neurosecretory and endocrine interactions in the Acari are based on these anatomical and histological data which also provide the basis for evolutionary considerations of anatomical relationships and specializations in the neurosecretory systems of other Arachnida.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1051450303
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  • 8
    Electronic Resource
    Electronic Resource
    Sensilla on the antennal flagellum of the sawyer beetles Monochamus notatus (Drury) and Monochamus scutellatus (Say) (Coleoptera: Cerambycidae) (1975)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 146 (1975), S. 513-531 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The antennae of the sawyer beetles Monochamus notatus and M. scutellatus were examined with the light and scanning electron microscopes to determine the types, number, distribution and innervation of the sense organs. Nine types of sensilla are described. Both short, thin-walled pegs (sensilla basiconica) and reversely curved thick-walled hairs (sensilla trichodea) are chemoreceptors. There are three types of long, thick-walled hairs (sensilla chaetica) which may be mechanoreceptors. One of these is modified in males to form unique snail-shaped pegs. A few dome-shaped organs, probably campaniform sensilla, were found.In addition to sense organs, many glands occur in association with the sensilla, and the antennae are well supplied with dermal glands connected by canals to small pores on the surface.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1051460407
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  • 9
    Electronic Resource
    Electronic Resource
    Neoplastic differentiation: Interaction of simian virus 40 and polyoma virus with murine teratocarcinoma cells in vitroSupported in part by grant DT-14-0 from the American Cancer Society, grants CA-16030, CA-13419 and CA-15823 from the National Cancer Institute and NIH training grant GM-00977. (1975)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 85 (1975), S. 179-187 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The host-virus interactions of Simian virus 40 (SV40) and polyoma virus (Py) with cell lines established from a teratocarcinoma were studied. The cells utilized in this study were the multipotential stem cell of the teratocarcinoma, embryonal carcinoma, and differentiated cells derived from embryonal carcinoma. Several lines of differentiated cells were established in vitro which included parietal yolk sac, epithelial, and spindle cell types. Embryonal carcinoma cells are not susceptible to infection by either SV40 or Py virus. However, differentiated cells are susceptible to infection by these viruses. The differentiated cells are permissive for Py virus replication and nonpermissive for SV40. Several continuously growing cell lines have been established from the SV40 infected cultures which express T antigen in 100% of the cells. The results indicate that undifferentiated embryonal carcinoma cells and their differentiated progeny respond quite differently to challenge with these two oncogenic DNA viruses.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1040850204
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  • 10
    Electronic Resource
    Electronic Resource
    Glucose utilization, pH reduction and density dependent inhibition in cultures of chick embryo fibroblasts (1975)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 85 (1975), S. 635-642 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The multiplication rate of sparse cultures of chick embryo cells is only slightly lower at pH 6.9 than at pH 7.4. There is, however, a marked reduction in the multiplication rate of the pH 6.9 cultures before they reach confluency. Cultures at pH 7.4 continue to multiply beyond confluency with only a slight decrease in the multiplication rate.Eighty to ninety percent of the glucose taken up by the cells growing at each pH is converted to lactic acid which is released into the medium. Metabolic reduction in pH of the medium is almost entirely accounted for by the amount of lactic acid produced by the cells. Neither the intracellular nor extracellular accumulation of lactic acid nor the accompanying reduction in pH is sufficient to explain density dependent inhibition of the rate of multiplication of chick cells.The rate of lactic acid production and the multiplication rate of chick cells are independent of glucose concentration in the range of 2-16 mM. In view of the kinetic parameters for the uptake of glucose, this shows that glycolysis is not limited by the rate of glucose uptake and that depletion of glucose from the medium cannot account for the onset of density dependent inhibition of multiplication. However, when cells reach very high population densities, conventional glucose concentrations of 5 mM can be depleted overnight by chick cells. Since the multiplication rate of cells is dependent on glucose concentration when it falls below 2 mM, depletion of glucose may cause some growth inhibition in crowded cultures supplied with conventional medium.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1040850316
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