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  • General Chemistry  (865)
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  • 2005-2009
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  • 1970-1974  (1.907)
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  • 1
    Digitale Medien
    Digitale Medien
    Viscosity of polypropylene oxide solutions over the entire concentration range (1970)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 10 (1970), S. 1-3 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: An empirical equation is presented which describes polymer solution viscosity, η, over the entire concentration range from a knowledge of intrinsic viscosity, [η], Huggins constant, k′, and bulk flow viscosity of polymer, η0. The equation is: \documentclass{article}\pagestyle{empty}\begin{document}$ \frac{{\eta _{sp}}}{{C[\eta]}} = \exp \left\{{\frac{{{\rm k'[}\eta {\rm]C}}}{{1 - bC}}} \right\} $\end{document} where solution viscosity, η, is contained in ηsp. No arbitrary parameters are invoked since b can be evaluated at bulk polymer (C = polymer density) where everything else is known. The equation accurately portrays the viscosity of polypropylene oxide (PPG 2025) from infinite dilution to bulk polymer in a very good solvent (benzene) and in a somewhat poorer (∼ θ) solvent (methylcyclohexane). The hydrodynamic consequences of the thermodynamic interactions between polymer and solvent are reflected in the constants. This equation should be applicable to other polymer/solvent systems, and thus be immediately useful to those working with concentrated polymer solutions.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760100102
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  • 2
    Digitale Medien
    Digitale Medien
    Entrance flows of polymeric materials: Pressure drop and flow patterns (1970)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 10 (1970), S. 24-31 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Flow at the entrance of a tube or channel is of interest in many polymer processes. Except for mathematical treatments at high Reynolds numbers and in creeping Newtonian flow, one must turn to empirical correlating equations and qualitative observations. These are discussed in two parts, one on pressure drop and the other on flow patterns. The discussion of pressure drop is largely a review, dealing with inertial, viscous, and elastic contributions to the pressure drop in tapered and sharp-edged entrances; also presented are new data for a viscoelastic polymer solution in tapered cone entrances. In the section on flow patterns, stress birefringent data for a very elastic solution flowing into a channel entrance show an unusual effect: stress discontinuities, not unlike “shock waves,” upstream and downstream of the entrances. This is in contrast to Newtonian and less elastic materials in which the stress patterns change gradually between the developed flow region and the entrance region.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760100106
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  • 3
    Digitale Medien
    Digitale Medien
    Compression, bending, and shear of bonded rubber blocks (1970)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 10 (1970), S. 48-53 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: An approximate theoretical treatment is given for small compressions of bonded rubber blocks. The component of the compressive force arising from the bonded condition at the loaded surfaces is obtained from a pressure distribution within the block, given by the solution of the corresponding torsion problem. The bending of blocks is treated in a similar way, the pressure distribution in this case being derived from the corresponding bending stress function. The apparent shear of relatively thick blocks is then treated as a combination of shear and bending displacements. The location of an internal rupture and the deformation at which it occurs are also derived from a critical (negative) value of the pressure developed within the block, at which a small cavity increases indefinitely in size. The corresponding critical deformations are calculated for extension and bending displacements. The shear stresses developed at the bonded surfaces under extension, compression or bending displacements are also evaluated.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760100110
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  • 4
    Digitale Medien
    Digitale Medien
    The rheology of polypropylene - the influence of molecular weight distribution on melt elasticity (1970)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 10 (1970), S. 79-85 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The structure of isotactic polypropylene, obtained by means of Ziegler-Natta catalysis, can be characterized only by molecular weight distribution. The mechanism of stereospecific catalysis eliminates other variables, i.e., short and long branching. In this case it is possible to develop a rheological study dependent only by polydispersity. The spectrum of relaxation times of five samples of polypropylene have been calculated from swelling measurement in the molten state and from flow master curves. The molecular weight distribution of the samples has been calculated by means of the relaxation spectrum, as suggested by Ferry. This information has been compared with that obtained by a fractionation method. There is a good agreement between the calculated and measured polydispersity curves.
    Zusätzliches Material: 13 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760100205
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  • 5
    Digitale Medien
    Digitale Medien
    Description of tensile failure of viscoelastic materials under multiaxial loadingWork Performed under the auspices of the U. S. Atomic Energy Commission. (1970)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 10 (1970), S. 102-107 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: A description of tensile failure of polymeric materials under multiaxial loading has been formulated, based on a combination of ideas and implications derived from Smith's work on uniaxial tensile failure envelopes and the author's earlier theoretical work. Some simplification of the formal expressions was achieved by imposing restrictions that would assure that the uniaxial failure envelope is recovered under uniaxial tensile stress conditions and that the progression toward failure is monotonically increasing under monotonically increasing loads. The final result emerges as an extension of the uniaxial failure envelope applied to failure under multiaxial loads. Subsequently, the result is capable of describing rate effects to the same extent as can be described by the uniaxial failure envelope. This is an added capability over many of the existing multiaxial failure descriptions. Unfortunately, the result applied at best, only to those materials for which the uniaxial failure envelope applies; thus the generality is restricted. Some preliminary verification is presented for LX-04-1, a high-explosive material composed of 85% HMX and 15% Viton by weight, using Peterman's results from 68°F biaxial tests. Further experimental work is underway.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760100208
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  • 6
    Digitale Medien
    Digitale Medien
    Mechanism of ultraviolet degradation and stabilization in plasticsPaper presented at Plastics Institute of American Seventh Annual Conference, November 6, 1969, Hoboken, N. J. (1970)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 10 (1970), S. 228-234 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: When plastics are used for outdoor applications, they often deteriorate fairly rapidly. Theoretical explanation is based upon absorption of ultraviolet energy, raising some bonds to an energy level which exceeds their stability, and thus initiating their breakdown, usually involving atmospheric oxidation and sometimes hydrolysis as well. This theory is satisfactory for many polymers, but does not explain the instability of some polymers which are transparent to ultraviolet, nor the stability of some polymers which contain ultraviolet-absorbing and/or unstable groups. Plastics are often stabiliized by addition of ultraviolet reflectors, absorbers, or deactivators, increasing stability sufficiently for outdoor use; theoretical explanation of their protective action is satisfactory when they work, but does not explain their specificity or their failures.
    Zusätzliches Material: 1 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760100408
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  • 7
    Digitale Medien
    Digitale Medien
    Mixing and residence time distribution in melt screw extruders (1970)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 10 (1970), S. 279-288 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The residence time distribution (RTD) functions were derived for screw extruders, based on the “parallel plate” and curved channel flow models. The results indicate a relatively narrow distribution, and they explain several characteristics of screw extruders. The strain distribution in the fluid across the channel was also derived. With the aid of these two functions an average strain of the fluid leaving the extruder was defined. The resulting weighted-average total strain (WATS) provides a quantitative criterion to the “goodness of mixing” in extruders.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760100505
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  • 8
    Digitale Medien
    Digitale Medien
    Gel sensitivity of polybutadiene-based rubber subjected to thermal abuse (1970)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 10 (1970), S. 159-162 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The thermal instability of polybutadiene-based rubber used to improve the impact strength of vinyl-type polymers often presents processing problems. Rubber manufacturers have attempted to alleviate this situation by incorporating various types of stabilizers. However, this is not always successful. One of the consequences of using a rubber that is not sufficiently stable in the production of modified vinyl-type polymers is the formation of insoluble gel particles during processing. In an attempt to prevent this from occurring, a test was developed that can differentiate between rubbers of acceptable and non-acceptable thermal stability. In principle, the test consists of exposing the rubber in question to a controlled thermal abuse of such intensity and duration as to approximate the thermal abuse to which the rubber will be subjected in a normal processing sequence. (The extent of abuse will vary for different processes and must be empirically established for each system.) Following this controlled exposure, the rubber is tested for gel-particle content by filtration of a specific solution, much the same way that the rubber manufacturer tests for initial gel-particle content. Sufficient data have been compiled to statistically describe the validity of the test.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760100306
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  • 9
    Digitale Medien
    Digitale Medien
    On the strength and stiffness of planar reinforced plastic resins (1970)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 10 (1970), S. 185-192 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The recent history of planar reinforced plastic resins, including glass flake, high modulus ceramic flake, and continuous vapor coated film composites, is reviewed. The theoretical mechanics of both continuous (film) and discontinuous (flake and ribbon) reinforcements are summarized in simple form. A novel set of design curves is presented from which the lower bound requirements for the flake composite constitutents may be read directly. At the same time, the dependence of the composite ultimate strength on the shear strength of the plastic resin matrix is demonstrated.The mechanical properties of experimental film and flake composites representative of recent work are reported and compared with the theoretical predictions. In conclusion, the potential of planar reinforced plastic resin composites is discussed and found to be significant for applications where low weight and high isotropic stiffness are required, for example in aero-structural, airfoil, or blade components.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760100310
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  • 10
    Digitale Medien
    Digitale Medien
    Torque rheometer evaluation of polypropylene process stability (1970)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 10 (1970), S. 215-221 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: A new method of treating torque rheometer test data has been developed. First, it involves converting the torque values measured over a range of temperatures to torques corresponding to a constant reference temperature. Then the log of the calculated torques is plotted against time. The method has been applied to several polypropylene grades, and the effects of numerous test variables have been explored. Correlations have been developed between torque rheometer data and fundamental polymer properties of viscosity and molecular weight. The method should also be applicable to polymers other than polypropylene.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760100405
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  • 11
    Digitale Medien
    Digitale Medien
    Masthead (1970)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 10 (1970) 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760100501
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  • 12
    Digitale Medien
    Digitale Medien
    Isothermal kinetic studies using a thermomechanical analyzer II. Rates of penetration of a polymer by a spherical indenterPart I Begins on page 300 of this issue. (1970)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 10 (1970), S. 305-308 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The use of a commercially available thermomechanical analyzer (TMA) operated in its isothermal mode is illustrated for studies of penetration of a hemispherically-tipped probe into a material sample. Two amorphous copolymers were studied at various temperatures above their softening points. Kinetics of penetration are compared with tensile creep measurements for these viscoelastic materials. A simple semi-empirical relationship between creep and penetration at small strains is applied and found to yield approximate although not exact agreement with experiment. It is thus possible that for homogeneous materials of this type creep data might be easily predicted with a fair degree of accuracy from penetration data and vice versa. Experimental problems involved in the TMA penetration technique are discussed.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760100509
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  • 13
    Digitale Medien
    Digitale Medien
    Dynamic melt properties of polymer blends (1970)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 10 (1970), S. 289-292 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The dynamic mechanical properties of blends of polymer melts were measured using the orthogonal rheometer. Two-phase blends, polyethylene-polystyrene, polyethylene-poly-(methylmethacrylate), and polystyrene-polymethylmethacrylate, were studied. The in-phase and out-of-phase moduli were measured over the range of composition and at frequencies between 10-4 and 10 revolutions/sec.The out-of-phase modulus increases in a monotonic manner with composition. The in-phase modulus, however, shows a maximum with composition in two cases. Examination of the relaxation spectra of these blends shows that when no maximum occurs it can be written as an additive function of the spectra of the components. In the case where a maximum is observed in the modulus the measured spectrum of the blend is shifted in frequency relative to the calculated one. This is tentatively attributed to slight interpretation and solubility of one phase in the other in these cases.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760100506
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  • 14
    Digitale Medien
    Digitale Medien
    Inflation and compression of rubber tubes between parallel plates (1970)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 10 (1970), S. 358-363 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: When a thin-walled rubber tube containing an incompressible fluid is compressed between two parallel plates the internal pressure rise depends on the restraints in the contact regions. When there is no friction in the contact zone the pressure rise is lower than when slip is prevented, so that the tube, regarded as a spring, has a compression stiffness which depends on the frictional conditions. The same considerations apply to the inflation of a tube between fixed parallel plates. In this case unstable inflation sets in at a critical pressure when the interfaces are frictionless; the tube develops a pronounced bulge when this pressure is approached. Simple theoretical relations are derived for the internal pressure and compressive force for both these deformations, and for both boundary conditions, assuming that the rubber is Neo-Hookean in elastic behavior. Experimental measurements on tubes of different dimensions are shown to be in reasonably good quantitative agreement with these theoretical predictions in all cases.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760100609
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  • 15
    Digitale Medien
    Digitale Medien
    Kinetics of thermally induced solid state polycondensation of poly(ethylene terephthalate) (1970)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 10 (1970), S. 364-368 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: A diffusional model was established to study the kinetics of thermally-induced solid state polycondensation of poly(ethylene terephthalate). Diffusion through solid polymer is the rate controlling step when temperature is higher than 210°C and particle size is no smaller than 100 mesh. The activation energy is 30 Kcal/g mole. In polymerizing powders (20-200 mesh), the crystallinity of prepolymer and its changes during the polymerization affect the diffusivity and thus the polymerization rate. The diffusivity was found to be linearly proportional to the mass fraction of the amorphous phase in PET polymer.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760100610
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  • 16
    Digitale Medien
    Digitale Medien
    Radiotracer measurements of sulphur diffusion in rubbers (1970)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 10 (1970), S. 383-387 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The object of measurement was the diffusion of elemental sulphur labelled with the radioisotope S35 in typical representatives for various types of rubber. The highest values of diffusion coefficient have been found in cis 1,4 polybutadiene. The lowest measured value was found for butyl rubber. The activation energy, expressing the temperature dependence of the diffusion coefficients, ranges from 4 to 10 kcal mol-1. For some rubbers studied, the activation energy is to a certain degree dependent upon temperature. The values of the diffusion coefficients and the characteristic constants for their temperature dependence are related to the mobility of the macromolecular segments.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760100613
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  • 17
    Digitale Medien
    Digitale Medien
    Rates of molecular vaporization of organic plasticizersBased on Research Supported by the Advanced Research Project Agency, Washington, D. C. 20301 (1970)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 10 (1970), S. 19-23 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The kinetics of the molecular vaporization process of 21 plasticizers were investigated in detail. By both isothermal and nonisothermal kinetic methods, it was evident that 11 were quite pure single compounds, while 10 were clearly mixtures of compounds. For the single component species internal energies for vaporization and rates of volatilization are listed. The internal energies of vaporization are about one-half or less of values one can estimate from the additive factor method of Small. Thus, solubility parameters based on our experimental values are low by about 30 percent. From this and previous work on linear alkanes, it is concluded that in the molecular vaporization process, the large organic molecules studied evaporate approximately as spheres and hence low values for the energy of vaporization are obtained. Consequently, the difference between our experimental energy and that estimated from solubility parameters is the energy for extending the molecule in a vacuum environment.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760100105
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  • 18
    Digitale Medien
    Digitale Medien
    Stress analysis of ribbon reinforced composites (1970)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 10 (1970), S. 43-47 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: In this paper the results of both the theoretical and experimental stress analyses of composite materials reinforced with ribbons are presented. The reinforcing materials for such composites are characterized as two-dimensional elements which are isotropic in planes parallel to the faces. The theoretical work is based on the finite element method. Experimentally, the photoelastic technique is employed to determine the stresses around the glass ribbons embedded in an epoxy matrix. The specimens, containing a number of aligned ribbons, were loaded in tension parallel to the ribbon width. The variation of shearing stress at the ribbon-matrix interface as well as the pertubation effect on both the ribbon normal stress and interfacial shear due to the discontinuity of the neighboring ribbons are discussed.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760100109
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  • 19
    Digitale Medien
    Digitale Medien
    Studies on the stress relaxation of polystyrenes in the rubbery-flow region (1970)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 10 (1970), S. 66-69 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Relaxation modulus curves for narrow distribution and broad distribution polystyrenes are compared and the significant effect of molecular weight distribution on these curves is shown. An empirical three-parameter equation is shown to describe the stress relaxation behavior of narrow distribution polystyrenes. New data for high molecular weight, narrow distribution polystyrenes are presented and used to extend the applicability of previous quantitative relations for higher molecular weights. The stress relaxation technique is shown to be sensitive to the type of plasticizer used at low concentrations.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760100203
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  • 20
    Digitale Medien
    Digitale Medien
    Effect of processing history on melt flow defects (1970)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 10 (1970), S. 94-101 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The two main flow defects which appear to originate in the processing machine or die are melt fracture and sharkskin. Both are associated with the elastic nature of the polymer melt. Processing variations that decrease the elastic nature of the melt diminish the severity of the effects of melt fracture. These include increased die length and temperature and shear at temperatures at which polymer segmental mobility is not too high. The sheared, less elastic melt structure may sometimes be stabilized by polymeric additives. A simple model is presented to account for this behavior, which is illustrated with examples of polyethylene and plasticized PVC.
    Zusätzliches Material: 13 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760100207
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  • 21
    Digitale Medien
    Digitale Medien
    Correction (1970)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 10 (1970), S. 130-130 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760100211
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  • 22
    Digitale Medien
    Digitale Medien
    Oxidation of ether linked thermoplastics (1970)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 10 (1970), S. 38-42 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Studies have been made of the heat and light induced oxidation of ether linked commercial thermoplastics using a variety of analytical methods. Our studies on polyoxymethylene, polyphenylene oxide, and its blends with polystyrene are discussed here. Comparisons of heat and light stability are made with thermoplastics previously reported.Heat aging of polyoxymethylene causes a decrease in elongation and weight as well as volatile product formation and changes in the infrared spectrum indicative of chain scission. Exposure to ultraviolet light accelerates the oxidative reaction. Polyoxymethylene copolymer is more thermally stable but both polymers are rapidly degraded during light aging.Investigation of the heat and light induced oxidation of polyphenylene oxide shows that oxidation, in either case, leads to a crosslinking reaction resulting in embrittlement of the polymer. The process is difficult to retard. However, oxygen uptake results indicate that blends of polyphenylene oxide and polystyrene can be suitably stabilized against thermal oxidation. Preliminary results indicate that oxidation of these blends proceeds by a chain scission mechanism.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760100108
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  • 23
    Digitale Medien
    Digitale Medien
    Polyvinylchloride melt rheology IIPart I is Reference 6. - the influence of molecular weight on flow activation energy (1970)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 10 (1970), S. 57-65 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The flow behaviors of a series of polyvinylchloride (PVC) resins covering a broad range of molecular weight have been examined at several temperatures. It has been shown that the influence of temperature on viscosity depends on the temperature range. That is, the flow activation energy is not constant but can be approximated by two values, one applicable to low temperatures, the other to high temperatures.The flow activation energy based on viscosities at constant shear rate decreases as the molecular weight increases. In contrast, the flow activation energy from viscosities at constant shear stress increases with molecular weight.The fact that the activation energy is dual valued does not seem to be associated with the polymer type. Both emulsion and suspension resins exhibit this behavior. Addition of certain modifiers appears to alter the activation energy at lower temperatures. These observations indicate that the shift in the activation energy in the low temperature range is due to a change in the flow mechanism.
    Zusätzliches Material: 15 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760100202
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  • 24
    Digitale Medien
    Digitale Medien
    Processing of boron filament wound composites (1970)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 10 (1970), S. 86-93 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Boron fiber reinforced composites have been extensively evaluated in epoxy resin matrix materials, which are satisfactory for applications in comparatively moderate environments, and are usually inapplicable at temperatures in excess of 400°F. For use in high temperature environments in excess of this figure, it is necessary to use more thermally stable resins. A modified phenolic resin was selected for this application because of the versatility of the material and the successful performance of phenolics in glass fiber reinforced structures. The modifications increased the viscosity and tack of the formulation so that consolidation could not be readily accomplished by a combination of tension and heat during the winding process, so that a multi-stage winding process with intermediate consolidation steps became necessary. Winding a complex path to make a uniformly thick wall on a frustrum required further modifications to the basic winding process. The successful solution of these problems and the development of structurally sound composites was the primary object of this work.
    Zusätzliches Material: 15 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760100206
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  • 25
    Digitale Medien
    Digitale Medien
    Masthead (1970)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 10 (1970) 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760100301
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  • 26
    Digitale Medien
    Digitale Medien
    Physical properties of some injection molded thermoplastics of various glass contents (1970)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 10 (1970), S. 139-147 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: This paper discusses the influence of fiber-glass reinforcement content on the physical properties of four theroplastic injection molded materials. In addition, the effects of binder difference (i.e., thermoplastic vs. thermosetting), associated with the reinforcement, are described.Several properties that were expected to show response to glass content and binder differences have been examined. Among these are short- and long-term tensile strength, flexural properties, compressive resistance, impact strength, deflection temperature under load (DTL), and environmental stress cracking.This work has demonstrated that fiber-glass reinforcement of the particular thermoplastics described in this paper has led to substantial improvements in both the stiffness and strength characteristics of the base resins. The responses to binder chemistry difference was found to be slight in many instances for the resins, as reflected by the tests described herein. However, the long-term tensile, impact, DTL, and stress-cracking tests have shown considerable sensitivity to binder change in some cases, especially with respect to the polypropylene, SAN and polyamide plastics. The particular response to a given binder system, however, appears to vary both with the material under test and the property used to detect such response.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760100303
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  • 27
    Digitale Medien
    Digitale Medien
    Capillary flow instability of ethylene polymer melts (1970)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 10 (1970), S. 193-203 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The capillary flow instability resulting in extrudate distortion has been studied for ethylene polymer melts using a molecular structure approach. It is found that the instability initiates at a critical value of elastic strain energy independent of (average) molecular weight for linear polyethylene. Once the flow breaks down, a slip interface within the melt is formed near the capillary wall, causing an abrupt increase in volumetric throughput. The velocity gradient within the melt remains continuous through the instability, however. Low molecular weight species present in the molecular weight distribution of linear polyethylene tend to suppress slip. Blends of linear and branched polyethylene exhibit instability behavior characteristic of both components throughout the entire range of composition. Results are discussed in terms of specific molecular mechanisms.
    Zusätzliches Material: 14 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760100402
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  • 28
    Digitale Medien
    Digitale Medien
    Polymer solubility parameters determined from measurements in a single solvent (1970)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 10 (1970), S. 222-224 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The solubility parameter of polyisobutylene has been determined from intrinsic viscosity measurements in a single solvent as a function of temperature. The change in solubility parameter of the solvent as a function of temperature was calculated form the equation \documentclass{article}\pagestyle{empty}\begin{document}$ \frac{{d{\rm}ln \delta s}}{{d{\rm}ln Vs}} = - \frac{{n + 1}}{2} $\end{document} where Vs, the molal volume, changes with temperature. The vlaue for the solubility parameter thus obtained compares well with values reported in the literature for intrinsic viscosity measurements in a series of solvents. Similar measurements were made with an ethylenepropylene copolymer. The solubility parameter of 87 mole % C2 ethylene-propylene copolymer was determined to be 8.1-8.6 in either toluene or methylcyclohexane.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760100406
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  • 29
    Digitale Medien
    Digitale Medien
    Quantitative thermal analysis of polyblends (1970)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 10 (1970), S. 247-250 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: A new quantitative thermal analysis technique was attempted on ABS and Noryl-type polyblends. A particular component within a polyblend was identified by its glass transition temperature and the amount of the component was determined from the increase in specific heat at the glass transition temperature.Two commercial Noryl resins were determined to be blends of high impact polystyrene and polyphenylene oxide in 47-47 and 69-17 proportions by weight, respectively. Polystyrene appears to be cosoluble with polyphenylene oxide without the formation of any complex. The PS-PPO polyblends yield single sharp glass transitions which are a function of concentration.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760100411
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  • 30
    Digitale Medien
    Digitale Medien
    Fine structures and fracture processes in plastic-rubber two-phase polymer systems III. Temperature dependence of Charpy impact strengthParts I and II of this series were published in the May 1969 POLYMER ENGINEERING AND SCIENCE. Part IV starts on page 261. (1970)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 10 (1970), S. 253-260 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Notched Charpy impact strengths of a series of plasticrubber two-phase polymer systems were measured over a wide range of temperatures. Blends of polyvinylchloride and rubbers with varying chemical structures, and several ABS polymers were investigated.In all systems, Charpy impact strength began to increase near the Tg of the rubber component followed by a logarithmic increase with increasing temperature. The trend is expressed by the following empirical relation: \documentclass{article}\pagestyle{empty}\begin{document}$$ I{\rm = }A{\rm exp(- }B/T{\rm)} $$\end{document} where I is Charpy impact strength, A and B are constants, and T is the absolute temperature. This equation is applicable between the Tg's of the plastic and the rubber components. The increasing tendency of impact strength, i.e. the B value of the above equation, is depressed mainly by the decrease of the compatibility and/or the interfacial adhesive force between the two phases. Toughening mechanism and the ways of increasing toughness are discussed based on the craze formation mechanism.
    Zusätzliches Material: 15 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760100502
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  • 31
    Digitale Medien
    Digitale Medien
    Processability of high-density polyethylene bottles with special reference to melt flow properties (1970)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 10 (1970), S. 235-240 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: A phenomenological treatment has been developed for correlations between melt flow properties of high-density polyethylenes and the processability of bottles. Defining two parameters for the flow properties, it was found experimentally that linear relationships hold satisfactorily between these flow parameters for the raw materials and those of corresponding extrudates. Several kinds of defects in high-density polyethylene bottles can be represented in terms of the flow parameters. These parameters may provide useful measures in predicting good appearance of bottles blow-molded with high-density polyethylene.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760100409
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  • 32
    Digitale Medien
    Digitale Medien
    Dynamic mechanical properties of poly(2,6-dimethyl-1,4-phenylene ether)-polystyrene blends (1970)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 10 (1970), S. 133-138 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Blends of poly(2,6-dimethyl-1,4-phenylene ether) (PPO) and atactic polystyrene (PS) have been prepared by mechanically mixing powders of the two polymers and subjecting the mixtures to three different thermal treatments. Three different compositions were studied by the dynamic mechanical and DSC techniques. The weight fractions of PPO in the mixtures were 0.25, 0.50 and 0.75. The dynamic mechanical measurements indicate that partial mixing took place but that two distinct phases, one rich in PS and the other in PPO, exist in all the mixtures studied. Each phase exhibits a characteristic relaxation peak associated with the glass transition of that phase. DSC measurements, on the other hand, reveal only a single glass transition apparently characteristic of the PS rich phase in each case. The results indicate that a given type of experiment will indicate compatibility or incompatibility depending upon the size of the molecular process it represents.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760100302
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  • 33
    Digitale Medien
    Digitale Medien
    Time-dependent properties of versamid cured epoxiesPresented at the Seventh Annual PIA Conference, Stevens Institute of Technology, November 5-6, 1969. (1970)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 10 (1970), S. 170-176 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Versamid cured-epoxy specimens were loaded in tension, compression, and flexure at different strain rates and temperatures to determine the yield stress and strain, and tangent, secant, and relaxation moduli. A torsion pendulum was used to measure the dynamic properties as a function of temperature and frequency. The time-temperature superposition principle was used to reduce this data to master curves. It was concluded that the time-temperature shift factors for secant moduli up to the yield point, for stress relaxation and for dynamic moduli were identical and were independent of the mode of loading. It was also shown that the presence of fillers or reinforcing agents likewise had no effect on the shift factors.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760100308
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  • 34
    Digitale Medien
    Digitale Medien
    Sources of variability in laboratory weathering (1970)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 10 (1970), S. 309-313 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: A statistical study was conducted to determine the significance of the sources of variability in the laboratory (carbon arc) weathering of a light-stabilized polyester resin system. Color fastness of the resin was evaluated in terms of changes in total color, lightness, and chromaticity. Factors that significantly influenced the results were variability within castings and between batches of resin, location of the specimen within the exposure apparatus, and the storage time prior to testing. The carbon arc instrument provided a relatively insensitive test for evaluating a light-stabilized polymer system, chiefly because, with a stable polymer, small random variations in response become almost equal to the small change in color developed on exposure.
    Zusätzliches Material: 7 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760100510
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  • 35
    Digitale Medien
    Digitale Medien
    High-temperature molding of pyrrones (1970)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 10 (1970), S. 340-344 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The cross-linked, ladderlike structure of cured pyrrones is not susceptible to forming at ordinary temperatures and pressures. At unusually high processing temperatures, of the order of 500°C, these intractable materials are observed to undergo transient flow sufficient to allow molding of the material. This observation, supported by analytical information, suggests that the flow occurs because of the breakage of covalent organic bonds and subsequent structural rearrangement of the cross-linked polymer network. This is in accord with a number of isolated reports of the pyrolytic behavior of several polymers.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760100606
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  • 36
    Digitale Medien
    Digitale Medien
    Masthead (1970)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 10 (1970) 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760100101
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  • 37
    Digitale Medien
    Digitale Medien
    Post extrusion heat and solvent transfer from polymeric film (1970)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 10 (1970), S. 4-12 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The problem of heat and solvent transfer from plasticized film is considered. The transport equations are solved by a numerical method. The formulation of the model includes the temperature dependence of diffusivity, the dependence of diffusivity on decreasing solvent concentration, as solvent leaves the film, and the latent heat of vaporization of the solvent. The Flory-Huggins theory is used as a model for vaporliquid equilibrium. Heat and mass transfer coefficients are taken either as constants (to simulate extrusion with blowing at the film surface) or from analytical solutions to the appropriate boundary layer equations (to simulate extrusion into a stationary medium.) The boundary layer theory takes into account the effect of rapid vaporization on heat and mass transfer coefficients. Several numerical solutions were obtained for cases corresponding to extrusion of polyvinylacetate, plasticized with acetone, extruded into air.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760100103
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  • 38
    Digitale Medien
    Digitale Medien
    Measurement of water vapor transmission through polyethylene electrical insulation (1970)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 10 (1970), S. 32-37 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: A method is described for measuring the rate of water vapor transmission through thick sections of polyethylene used as insulation on electrical conductors of pure sodium metal. The technique could be generally useful for materials which do not react with sodium, and for cylindrical samples which can be filled with molten sodium in a dry box. For samples with uniform dimensions the results are extremely precise because sensitive electrical measurements are used. Specimens of products in final form can be employed to determine the effects of variations in processing.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760100107
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  • 39
    Digitale Medien
    Digitale Medien
    Masthead (1970)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 10 (1970) 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760100201
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  • 40
    Digitale Medien
    Digitale Medien
    Flow behavior of concentrated solutions of an SBS block copolymer (1970)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 10 (1970), S. 70-78 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The non-Newtonian viscosity of concentrated solutions of a styrene-butadiene-styrene, SBS, block copolymer was measured with a novel capillary viscometer. Polymer concentrations ranged from 0.165 to 0.306 g/cc. Apparent shear rates ranged from 1 to 105 sec-1. Five different solvents were employed. All of the flow curves can be reduced to a single master curve with the same shape exhibited by monodisperse polystyrenes and the Graessley theory. The shift factor for the shear rate axis, τ0, approximately parallels the Rouse relaxation time, τR, but shows a residual concentration and solvent dependence not predicted by the Rouse form. For different solvents at the same concentration, better solvents show a minimum relative zero shear viscosity, η0/ηs, and a maximum ratio τR/τ0. It is concluded that all solvent effects are not adequately incorporated into the zero shear viscosity for the purposes of constructing master plots; however, the shape of the master plot is not affected by the solvent or the polymer block structure.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760100204
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  • 41
    Digitale Medien
    Digitale Medien
    Cause and effect in the weathering of plastics (1970)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 10 (1970), S. 108-121 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: In most instances, the study of the weatherability of plastics follows empirical schemes that show little correlation with the actual effects of outdoor exposure. A more reliable analysis must be based on a knowledge of the factors in the weather which affect plastic properties and of the modes of interaction between these factors and the plastic material. It is shown that both the factors of the weather and the kinetics of polymer degradation may be expressed in a quantitative manner suitable for analytical treatment. Furthermore, it is shown that the analytical approach yields predictions which are in qualitative agreement with the results of actual outdoor exposure. Finally, some new techniques are proposed for more reliable predictions of long-term outdoor weatherability on the basis of laboratory studies.
    Zusätzliches Material: 24 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760100209
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  • 42
    Digitale Medien
    Digitale Medien
    Temperature dependence of the properties of low-density polyethylene (1970)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 10 (1970), S. 122-130 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The dynamic mechanical properties of low-density polyethylene melts were measured as a function of frequency and temperature using the Orthogonal Rheometer. These results were expressed in terms of the components G′ and G″ of the dynamic modulus and the components η′ and η″ of the dynamic viscosity. The functions J′, J″, η*, and G* were also calculated from the results.The method of reduced variables or time-temperature superpositions was attempted on the results. The classical method was found to require modification to be applied to these low-density polyethylenes. From this modified form of the reduced variables technique, the temperature dependence of the elastic and viscous parts of the response could be separated.The experimentally determined temperature dependence of the elastic part of the response was found not to be in accord with the accepted theory of rubber elasticity.The temperature dependence of the viscous part of the response is discussed in terms of the concept of flow activation energy, and clarification of this term is explored. It is concluded that the temperature dependent properties of polymer melts are best compared at equivalent time scales of response in the non-Newtonian region. In order to do this the temperature dependence of the elastic part of the response must be included explicitly in the reduction scheme.
    Zusätzliches Material: 21 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760100210
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  • 43
    Digitale Medien
    Digitale Medien
    Surface fracture in injection molding of filled polymers (1970)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 10 (1970), S. 154-158 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: In injection molding certain polymers, fracture of the polymer stream sometimes occurs at the mold surface. This phenomenon has been found to be a tearing apart of the polymer surface layer accompanied by downstream slip of the flowing melt at the polymer/mold interface. Fracture occurs early in mold filling and is initiated usually at the gate to the mold cavity. Analysis of the fracture mechanism indicates that fracture is caused by: (1) high shearing stress in the melt as it fills the mold; (2) poor polymer/mold adhesion; and (3) low polymer surface cohesive strength.
    Zusätzliches Material: 15 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760100305
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  • 44
    Digitale Medien
    Digitale Medien
    Relationship between thermoelasticity and reinforcement in elastomers: Silica filled silicone elastomers (1970)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 10 (1970), S. 177-184 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Increases in modulus, tensile strength, and swelling caused by reinforcing silicone rubber with silica filler were correlated with the thermoelastic parameter, fe/f. A new semiempirical equation of state, containing a generalized front factor, was derived to explain the experimental results. While the retractive force in pure gum elastomers is largely entropic in origin, reinforcement in silicone rubber-silica systems appears to arise by greatly augmenting the deformational free energy change stored in energetic modes.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760100309
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  • 45
    Digitale Medien
    Digitale Medien
    Extrusion blow molding of polyvinyl chloride homo- and copolymers (1970)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 10 (1970), S. 204-208 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Dynamic mill stability tests of PVC powder blends at the equiviscous temperatures were correlated with the clarity and color obtained in extrusion and blow molding of bottles. Copolymers of vinyl chloride with alkyl vinyl ether and propylene in a calcium-zinc stabilizer, impact modified formulation had better processability than a homopolymer and produced bottles having lower values of absorbance and yellowness index. Product imperfections which were evident in blow molding of dry blends, but not during milling or capillary rheometer extrusion, were found to be related to the particle size distribution and volatile content of the resin.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760100403
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  • 46
    Digitale Medien
    Digitale Medien
    Thermal stability of networks containing siloxane linkages (1970)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 10 (1970), S. 225-227 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The thermal stability of elastomers containing siloxane linkages has been compared using the technique of chemical stress relaxation in an inert environement. Enhancement of the already high stability of the basic poly (dimethyl siloxane) silicone rubber by the substitution of hetero groups in and on the main chain was proved, with the exception of the pendent trifluoroporopyl group. Particulary dramatic was the effect of the mcarborane moiety in the SiB-2 elastomers which elevated the stability of the siloxane chain by more than 100°C relative to silicone rubber.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760100407
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  • 47
    Digitale Medien
    Digitale Medien
    Evaluation of biocides for treatment of polyvinyl chloride film (1970)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 10 (1970), S. 241-246 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The results of a study to determine the biological stability of clear, colorless, biocide-treated PVC film are presented. With the exception of a resistant control, all the PVC film samples tested contained a plasticizer susceptible to biological deterioration. Biocide-treated and control PVC film samples were subjected to biological attack in soil burial. Portions of each sample were exposed to leaching and to weathering in a weatherometer followed by soil burial to test the stability of each biocide to loss by water and weathering exposure. Of the 32 biocide preparations tested only 2, N-(trichloromethylthio) phthalimide and copper 8-quinolinolate, a known effective reference compound, were found to provide good protection for treated film in direct soil burial and in soil burial following leaching and weatherometer exposure. Natural weathering outdoors confirmed the results found with weatherometer exposed samples. The N-(trichloromethylthio) phthalimide was less effective than the reference compound in suppressing surface growth. In addition, N-(trichloromethylthio) phthalimide may not be compatible with all PVC formulations.
    Zusätzliches Material: 4 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760100410
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  • 48
    Digitale Medien
    Digitale Medien
    Fine structures and fracture processes in plastic-rubber two-phase polymer systems IV. Temperature and strain rate dependences of tensile propertiesPart III of this series is presented on page 253, of this issue. (1970)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 10 (1970), S. 261-267 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Yield stress (σY) and elongation to break (εb) were measured over a wide range of temperature under three different strain rates (\documentclass{article}\pagestyle{empty}\begin{document}$ \dot \varepsilon $\end{document}) for a series of polyvinylchloride-rubber blends, ABS polymer and high-impact polystyrene. It was found that a temperature-strain rate reduction was possible for σY and the composite curve obtained by the superposition was expressed by the following relation: \documentclass{article}\pagestyle{empty}\begin{document}$$ \sigma _{\rm Y} = K_1 + K_2 \log \dot \varepsilon A_T $$\end{document} where K1 and K2 are the material constants, and AT is the shift factor.As for εb, a new maximum was found at around room temperature in addition to the known maximum at around the glass transition temperature of the matrix phase. The results are discussed in terms of the craze theory for rubber toughening of plastics.
    Zusätzliches Material: 14 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760100503
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  • 49
    Digitale Medien
    Digitale Medien
    A modified melting model for plastifying extrudersPresented at the AIChE 67th National Meeting, held in Atlanta, Ga., Feb. 15-19, 1970. (1970)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 10 (1970), S. 268-278 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The extursion melting model of Tadmor et al. (1967) has been modified to include the effects of screw channel curvature and melt leakage through the screw flight-barrel clearance. An alternate coordinate system was used in modifying the model to simplify the addition of curvature corrections. Also proposed is an improved method of computing solid bed velocity. A substantial number of typographical errors and truncations appeared in the original data published by Tadmor et al., and verification of their computations with corrected data was successful in all cases. Channel curvature corrections and the improved method of computing solid bed velocity increased the predicted rate of solid bed width decrease by approximately 14% during the initial stages of melting. Addition of leakage flow to the model tended to offset this effect completely or in part. Leakage flow effects always predominated during the later stages of melting, however. These effects may interact differently for other extruder sizes or screw designs; therefore, the modified melting model should be a more accurate model for use in the design of extruder screws and in studies of extruder performance.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760100504
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  • 50
    Digitale Medien
    Digitale Medien
    Isothermal kinetic studies using a thermomechanical analyzer I. Rates of polymer swelling and dissolutionPart II of this series starts on page 305 of this issue. (1970)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 10 (1970), S. 300-304 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The use of a commercially available thermomechanical analyzer (TMA) operated in its isothermal mode is illustrated for studies of polymer-swelling and dissolution in liquids. Results for a variety of polymer-swelling agent systems demonstrate that information usually requiring more sophisticated experimental techniques can be readily obtained with the TMA. In particular rates of swelling and penetrant diffusion coefficients can be determined for selected systems. Dissolution measurements, exemplified here for polystyrene in three different solvents, can be utilized to obtain steady state rates of solvent penetration and rough estimates of the interdiffusion coefficient for a system. The experimental limitations involved in both types of measurement are discussed.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760100508
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  • 51
    Digitale Medien
    Digitale Medien
    Spe international award paperThe SPE International Award was presented to Professor A. V. Tobolsky at the 28th Antec, held May 4-7, 1970, in New York City. (1970)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 10 (1970), S. 317-319 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760100602
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  • 52
    Digitale Medien
    Digitale Medien
    A new mthod for determining oven aging stability of polypropylene monofilament (1970)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 10 (1970), S. 332-339 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: A precise method of oven-aging polypropylene monofilament has been developed employing a tubular oven in which temperature and air velocity within each tube are accurately controlled. The monofilaments are suspended within each tube by means of specially construced heat stabilized polypropylene holders (no metal contact), which facilitate handling and record keeping. Each filament is held in an attitude perpendicular to the air flow. Failures almost invariably occur in the middle of each filament. Oxidative stabilities of filaments aged in the tubular oven at a constant temperature and air flow were found to be dependent upon (a) distance of the filaments from the incoming air side and (b) whether the exposure was continuous or intermittent. If these parameters are kept constant, relatively good precision can be obtained. The 95% confidence level for a single observed value was found to be on the order of ±10% of the average oven stability within the whole oven and ±7% within a single tube. Precisions of about ±2.5% can be obtained by employing averages of 10 replicates exposed on the same specimen holder.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760100605
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  • 53
    Digitale Medien
    Digitale Medien
    Anomalous transport of hydrocarbons in polystyrenePresented at the Seventh Annual PIA Symposium on “Time Dependent Properties of Plastic Materials,” Stevens Institute of Technology, Hoboken, N. J., Nov. 5-6, 1969. (1970)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 10 (1970), S. 376-382 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The transport kinetics and equilibrium concentrations of n-pentane at high penetrant activities in cast, annealed polystyrene were determined and compared with similar measurements in biaxially-oriented polystyrene. The rate of Case II (relaxation-controlled) sorption in biaxially-oriented polystyrene is three to four times faster than the sorption rate in cast, annealed polystyrene. The Case II sorption process in biaxially-oriented polystyrene is more highly temperature dependent than in cast, annealed film. The higher activation energies coupled with the larger relaxation-controlled sorption rates in biaxially-oriented polystyrene imply the involvement of larger polymer segments in the rate controlling polymer relaxations. The sorption in cast, annealed polystyrene was a position-dependent relaxation controlled transport process; in contrast the sorption in biaxially oriented polystyrene, albeit relaxation-controlled, was not position dependent. The position dependence of the Case II sorption appears to be a consequence of the presence of residual benzene in the film which accelerates the rate-determining relaxations. Desorption measurements at very low penetrant activities were quite similar for both biaxially oriented and cast, annealed polystyrene. The desorption kinetics were Fickian and were only a weak function of polymer orientation at these low activities.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760100612
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  • 54
    Digitale Medien
    Digitale Medien
    Masthead (1970)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 130 (1970) 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051300101
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  • 55
    Digitale Medien
    Digitale Medien
    The fine structure of the tegument of Tylocephalum metacestodes: With emphasis on a new type of microvilliThis research was supported in part by a grant (Contract 14-17-007-662G) from the Bureau of Commercial Fisheries, U.S. Department of the Interior, and in part by a grant from the NIH Institutional Biomedical Research Fund, University of Hawaii. (1970)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 130 (1970), S. 11-23 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Electron microscope studies on Tylocephalum metacestodes embedded in the tissues of the oyster, Crassostrea virginica, have revealed that the tegument of the larval tapeworm is comprised of an external and an internal level which are partially separated by a basal lamina and two layers of muscles. The outer tegumentary level is comprised of an anucleate, cytoplasmic syncytium in which are embedded large and small vesicles and mitochondria. Surfacial hooks are also embedded therein. The internal level is comprised of relatively large discrete cells including mitochondria, rough endoplasmic reticulum, and large and small vesicles. These cells are intermittently connected with the external level by cytoplasmic bridges.Arising from the external level are unusual microvilli each of which terminates as a spherical vesicle. The stem of each microvillus is covered by a unit membrane which is continuous with that overlaying the body surface. In addition, each microvillus includes an external layer of medium electron density, a medial layer of intense electron density, and a core of heterogenous, medium electron density. These structures may be intertwined and bundles can be observed at the light microscope level as fibril-like projections from the parasite's body surface. One of their possible functions may be to prevent intimate contact between the encapsulating fibers of host origin and the parasite's body surface. In addition, the contraction and distention of the circular muscles result in microvillar movement which may keep the surrounding host fluids, including those of nutritional importance to the parasite, in a state of flux thus hypothetically permitting more uniform uptake.The abundance of vesicles in the syncytial external level of the tegument appears to be characteristic of the more primitive marine cestodes belonging to the orders Trypanorhyncha and Lecanicephala.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051300104
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  • 56
    Digitale Medien
    Digitale Medien
    Masthead (1970)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 130 (1970) 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051300201
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  • 57
    Digitale Medien
    Digitale Medien
    Histogenesis of the cuticle of the adult flies, Sarcophaga bullata and S. argyrostomaThis investigation was supported in part by a Public Health Service Research Career Award 5-K06-GM-18,495, by grant AI-00533 from the U.S.P.H.S. and grant GB 5441X from the N.S.F., made to G. F., and is part of a thesis submitted by W. F. in partial fulfillment of the requirements for a Ph.D. in entomology at the University of Illinois. (1970)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 130 (1970), S. 137-149 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Sequential patterns of cuticle deposition and “melanization” in the imaginal cuticle of Sarcophaga argyrostoma in parts of the body darkening before or after emergence are examined on a histological basis. The patterns in the cuticles examined range from a simple absence of “melanization” to a complex of histological changes involving “melanization” and deposition. Ultrastructural changes in the post-emergent cuticle of Sarcophaga bullata during the hardening and darkening process and cuticle deposition are described.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051300203
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  • 58
    Digitale Medien
    Digitale Medien
    Morphology of the trunk of Corynosoma hamanni (acanthocephala: Polymorphidae) (1970)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 130 (1970), S. 151-161 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Morphological study of Corynosoma hamanni (Linstow, 1892) was continued with the intention of presenting a morphological description of a single, well defined species.Sexual dimorphism is exhibited in body size, males being larger, and in body spination. Trunk spines are arranged in a pattern similar to that of Corynosoma semerme and do not extend onto the bursa as reported in the original description of C. hamanni.Two testes, located side by side, are followed by six cement glands arranged in two groups of three glands each. One group is behind each testis. Cement ducts from glands on the right side cross over Saefftigen's pouch and join to form a reservoir on the left side; ducts from cement glands on the left side fuse forming a second reservoir. The two cement reservoirs unite before emptying into the ejaculatory duct. The bursa possesses rays on its outer wall and numerous, well-developed papillae in the muscular cap.In females, a ruptured genital ligament sac is attached partially on the dorsal wall of the uterine bell and partially on a column of six cells projecting from the bell's base into its lumen. Postericrly the dorsal wall of the bell has two protruding pockets behind which occur ten cells composing the selector apparatus. Dorsal openings into the pseudocoelom occur on either side of the uterine bell. Two muscular tubes conduct eggs into the uterus. Female C. hamanni frequently form genital vestibules in which the genital pore occurs along the dorsal wall and not, as reported for some species, at the anterior tip.Eggs of C. hamanni possess four membranes rather than the previously reported three.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051300204
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  • 59
    Digitale Medien
    Digitale Medien
    Microscopic anatomy of the cardiac ganglion of Limulus polyphemusThis study was supported in part by Public Health Service Research grant HE-09718, from the National Heart Institute. (1970)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 130 (1970), S. 385-395 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The morphology of the cardiac ganglion of Limulus polyphemus (L) was examined by reconstructions from stained serial sections. This ganglion is composed of two distinct parts: a fiber tract extending the entire length of the heart and a cellular portion underlying the fiber tract. The cellular portion extends continuously from the third pair of ostia to the posterior terminus of the heart. The mean number of ganglion cell bodies is 231. Most of the ganglion cells are located among the glial elements of the cellular portion. The greatest density of cells is found in segments 5 and 6. Six cell types are recognized: (1) large pigmented unipolar cells approximately 120 μ in diameter with distinct connective tissue capsules around them; (2) large pigmented bipolar cells approximately 120 μ in length which are also encapsulated; (3) pigmented multipolar cells approximately 80 μ in diameter which are free of capsules; (4) small pigmented bipolar cells approximately 40 μ in length which are encapsulated but which are found exclusively within the fiber tract; (5) non-pigmented multipolar cells approximately 30 μ in diameter which are found scattered among the connective tissue elements of the cellular portion; and (6) small non-pigmented cells approximately 10 μ in diameter which are found within the unipolar cell capsule and scattered among the connective tissue elements of the ganglion.The variability in cell numbers and the random location of cells points toward non-specific anatomical connectivity between elements of this ganglion.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051300309
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  • 60
    Digitale Medien
    Digitale Medien
    Histogenesis of Swiss white mouse secondary palate from nine and one-half days to fifteen and one-half days In utero. I. Epithelial-mesenchymal relationships - light and electron microscopyThis work was supported by Research grant DE 03002 from the National Institute of Dental Research, NIH. (1970)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 130 (1970), S. 435-449 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Development of the secondary palate in Swiss white mouse embroyos was studied from age nine-and-one-half days in utero to the stage of mesenchymal coalescence in the secondary palate (approximately fifteen-and-one-half days). The greatest changes observed occur in the mesenchyme. At early stages, mesenchymal cells underlying oral ectoderm of the head are few and only occasionally contact the ectoderm. Electron micrographs show large intercellular spaces between the ectodermal cells. As embryogenesis continues, the mesenchymal cells become more numerous, closer to each other and closer to the epithelium. Just prior to horizontal transposition of shelves, the mesenchymal cells spread farther from each other and from the palatal epithelium and epithelium of the palatal tip becomes stretched. Ultrastructurally the intercellular spaces between epithelial cells of the palate tip have become much smaller. Some mitochondria in some epithelial cells are swollen and have clear matrices and distorted cristae. The shelves become horizontal and meet in the midpalate. Cells with degeneration bodies are seen in the epithelial seam. The seam undergoes autolysis and is replaced by mesenchyme. The morphological changes described, particularly in the mesenchyme, may play an important role in determining the effect of various teratogens at different stages of palatal development. The changes in both mesenchyme and epithelial cells in the later stages may constitute part of the process of preparing shelves for fusion as postulated by Pourtois ('66).
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051300404
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  • 61
    Digitale Medien
    Digitale Medien
    Tooth replacement patterns in young Caiman sclerops (1970)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 130 (1970), S. 501-509 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Although there are many reports of tooth replacement patterns in lower vertebrates, few show the range of pattern to be found in a number of similar aged specimens of one species. Fifteen specimens of Caiman sclerops, head length 4-5 cms, were examined by a radiographic technique and their tooth replacement patterns analysed. Whole head radiography and dissected head radiographs were compared and the resulting tooth replacement waves were found to be comparable. Wave replacement (sensu Edmund, '60) in odd and even tooth positions in the tooth row was observed in all the specimens examined. Whereas most waves passed in a cephalad direction, wave reversal (caudad) was also observed, particularly in the anterior parts of the jaws. In some specimens simple alternation in tooth replacement was observed, particularly in the mid-portion of each quadrant. The smooth, age-related change-over from cephalad to caudad demonstrated by Edmund ('62) in captive Alligator mississippiensis was not observed in wild specimens of Caiman sclerops.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051300409
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  • 62
    Digitale Medien
    Digitale Medien
    Histogenetic pleiotropism in the crooked neck dwarf chick embryo: Degeneration of the trachea and thymus (1970)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 131 (1970), S. 89-101 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Retrogressive analysis of the cn gene effect has been performed on crooked neck dwarf chick embryos between stages 28-38 (5-12 days). The phenocritical stage of mutant embryos studied is stage 29. Histolytic degeneration of neck tissues is first recognized by the appearance of localized degenerate nuclei in the tracheal mesenchyme. Pleiotropic autolysis of the embryonic thymus, loose mesenchyme and the ventral neck tissue is also observed. Histolysis occurs in a caudocephalic gradient in all cn-affected embryos. The degenerative effects in crooked neck dwarf embryos vary in their intensity, but the pattern of autolysis seems constant. Histological observations provide some explanation for “escapers,” homozygous lethal embryos known to survive until hatching. A mechanism for surviving developmental crises in cn embryos is proposed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051310106
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  • 63
    Digitale Medien
    Digitale Medien
    Analysis of the development of the lizard, Calotes versicolor. I. A series of normal stages in the embryonic developmentSupported by Research grant HD 02065 from United States Public Health Service. (1970)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 130 (1970), S. 479-489 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: It has been shown that the external parameters of eggs of the garden lizard, Calotes versicolor, are not suitable for assessing the exact developmental stages of embryos. In order to make use of this lizard's embryos for experimental work, a series of developmental stages has been characterized, using various morphological features.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051300407
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  • 64
    Digitale Medien
    Digitale Medien
    The cytology of the vitellogenic stages of oogenesis in Drosophila melanogaster. II. Ultrastructural investigations on the origin of protein yolk spheres (1970)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 130 (1970), S. 467-478 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The cytology of the vitellogenic stages in the development of the oocyte of Drosophila melanogaster is described following an electron microscopic study of sections of plastic-embedded ovaries and single egg chambers. One of the first morphological manifestations of yolk deposition is an infolding of the plasma membrane of the oocyte and the abscission of membranous tubules and vesicles. The protein (alpha) yolk spheres originate along the oocyte periphery from membranous sacs to which are attached membranous tubules. It is assumed that the majority of the protein within the alpha sphere is synthesized by neighboring tubular, rough surfaced endoplasmic reticulum. The other organelles in the ooplasm are described, and their origin and possible roles in vitellogenesis are examined. The relative importance of intra- and extra-ovarian synthesis of yolk protein in different insect species is discussed.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051300406
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  • 65
    Digitale Medien
    Digitale Medien
    Evidence for the fusion of myoblasts in amphibian embryos. II. Xenoplastic transplantations of somitic cells from anuran to urodele embryosSupported by United States Public Health Service Graduate Training grant GM 658, and National Science Foundation grant GB-2125, awarded to Professor Johannes Holtfreter.Submitted to the University of Rochester in partial fulfillment of the requirements for the degree of Doctor of Philosophy. (1970)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 130 (1970), S. 491-500 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: In order to further support the thesis that myoblast fusions lead to the formation of multinucleate myotubes during early amphibian development, prospective myoblasts from frog embryos (Rana pipiens; Xenopus laevis) were orthotopically and heterotopically transplanted into embryonic salamanders (Ambystoma maculatum; A. tigrinum). The stages employed ranged from gastrula to early tail bud. After the hosts had developed to more advanced stages, they were fixed, sectioned in the frontal plane, and prepared for histological observation. Of special interest in these xenoplastic combinations are the nuclear and cytoplasmic differences between anuran and urodele embryonic cells.In most cases, transplanted cells tended to form a tissue complex distinct from the host tissues. This naturally decreased the opportunity for cell intermingling and consequently reduced the chances for fusions between graft and host myoblasts. Thus, there was a correlation between the extent of dispersion of the transplanted cells and the frequency of chimeric myotubes. Nevertheless, in each experimental series, a number of multinucleate myotubes emerged consisting of nuclear and cytoplasmic components of both graft and host cells. These chimeric myotubes, which must have originated by multiple cell fusions of anuran and urodele cells, (1) retained their distinct nuclear differences, (2) displayed resorption of both anuran and urodele yolk platelets, and (3) contained cross-striated myofibrils. The function of these chimeric cells, their synthesis of myofibrils, and the apparent lack of free intermingling at the cellular level, are discussed.
    Zusätzliches Material: 1 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051300408
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  • 66
    Digitale Medien
    Digitale Medien
    The body wall of cheilostome bryozoa. III. The frontal wall of Watersipora arcuata banta, with a revision of the cryptocystideaThis work was submitted to the graduate faculty of the Department of Biological Sciences at the University of Southern California in partial fulfillment of the requirements for the degree of Doctor of Philosophy. The research, conducted at the Allan Hancock Foundation and the Friday Harbor Laboratories of the University of Washington, was supported in part by an NIH Biomedical support grant award, an NSF graduate training grant, and by an NDEA Title IV Graduate Student Fellowship. Contribution 336 of the Allan Hancock Foundation. (1970)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 131 (1970), S. 37-56 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: (1) The frontal wall of the encrusting cheilostome, Watersipora arcuata is a one-layered, evenly perforated calcareous shield which subdivides the metacoel into two compartments, the perigastric coelom and the hypostega. These compartments communicate through four and six “intrazoidal septulae” at the corners of the frontal wall. (2) The frontal wall develops by apposition independently of the ectocystal epitheca. The ascus develops as an invagination of the epitheca. These observations are consistent only with the view that the frontal wall of this species is a cryptocyst. (3) The terms “tremocyst,” “olocyst,” and “pleurocyst” are poorly understood and ambiguously defined; they should not be used until more information is available. (4) The taxa Anasca, Ascophora, Ascophora Imperfecta, and Ascophora Vera are polyphyletic and should ge dropped and replaced by Silén's (1942) more natural taxa. Silén's Cryptocystidea should be enlarged to include Watersipora and related ascusbearing cheilostomes.
    Zusätzliches Material: 26 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051310104
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  • 67
    Digitale Medien
    Digitale Medien
    Observations on the pineal system in the hamster. I. Relations of the superficial and deep pineal to the epithalamusSupported by USPHS grants AM-12938, HD-02937 and NSF, GB-8439. (1970)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 131 (1970), S. 153-161 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: A mass of pineal tissue has been observed associated with the habenular commissure and the apex of the pineal recess in the golden hamster. Previously, it had been thought that all of the pineal system in the hamster was located at the confluence of sinuses just beneath the skull. To distinguish the two components of the pineal system, that in the dural position is called the superficial pineal and the mass associated with the habenular commissure is called the deep pineal.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051310203
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  • 68
    Digitale Medien
    Digitale Medien
    Masthead (1970)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 131 (1970) 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051310301
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  • 69
    Digitale Medien
    Digitale Medien
    Masthead (1970)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 130 (1970) 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051300401
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  • 70
    Digitale Medien
    Digitale Medien
    Spermiogenesis in the spider, Pisaurina Sp.: A fine structure studyThis work was supported by U.S.P.H.S. grant NB-06285.The author wishes to express his grateful appreciation for the excellent technical assistance given by Mrs. Ann Florendo and Miss Lou Gipson during the course of this investigation. (1970)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 130 (1970), S. 421-433 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: A fine structure study of spermatids and spermatozoa of the spider, Pisaurina sp. demonstrates that early spermiogenesis is similar to other flagellate spermatozoa. An acrosome forms from a Golgi-derived, acrosomal vesicle, a perforatorium indents acromosome and nucleus, a flagellum with a three-plus-nine tubule substructure is formed and nuclear chromatin condenses during spermiogenesis. Divergence from typical spermatozoa includes the presence of a three-tubule substructure of the central flagellar shaft, progressive rounding-up of late spermatids with concomitant incorporation of previously formed flagellum. This evidence is presented in terms of its possible functional significance in fertilization and gamete fusion in spiders.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051300403
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  • 71
    Digitale Medien
    Digitale Medien
    Neurosecretion in the scorpion Heterometrus swammerdami (1970)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 131 (1970), S. 1-15 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Gross morphology, staining characteristics and mapping of the diversity of the neurosecretory cell types in the brain and subesophageal ganglion of the scorpion Heterometrus swammerdami are reported. Special neurosecretory cell groups whose product is stainable with orange-G, acid fuchsin and Heidenhain's hematoxylin are present in the brain.In many of the living isolated neurosecretory cells, the secretory material appears luminous when viewed with dark ground illumination and granular when observed with phase contrast microscope.In the subesophageal ganglion the metameric arrangement of neurosecretory cells is distinct. Neurosecretory product accumulating in specific regions of subesophageal ganglion, and its axonal transport into the dorsal nerves and their termination in cephalic blood vessels apparently representing a storage and release organ of neurosecretion is reported.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051310102
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  • 72
    Digitale Medien
    Digitale Medien
    Placentation in the garter snake, Thamnophis sirtalisSupported in part by a USPHS Predoctoral Fellowship and by National Science Foundation Research grants G-24043 and GB-6435 to W. A. Wimsatt. (1970)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 131 (1970), S. 57-87 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The placental memebranes and uterus of the garter snake, Thamnophis sirtalis, were studied using histological, histochemical, electron microscopic, dye transfer, and radioisotopic techniques. The conceptuses are completely enclosed throughout gestation by a transparent shell membrane which is produced by glandular epithelia in the uterine segment of the oviduct.Both chorio-allantoic and omphalo (yolk-sac) placentation are observed in this snake. The growth of the extra-embryonic mesoderm takes place in a manner peculiar to placental reptiles, and results in the isolation of the omphaloplacenta from the yolk-sac wall. On the basis of morphology, enzyme histochemistry, and phagocytosis of Trypan blue particles, this structure is interpreted as a site of histiotrophic absorption.The chorio-allantoic region of placentation is simple in structure. Fetal and maternal capillaries are closely apposed but always separated by layers of uterine and chorionic epithelium and the thin shell membrane. The placental membranes of the garter snake are similar in many respects to those of other live-bearing snakes, but less specialized than most lizard placentate.Isotopically labelled sodium and glycine are passed to the fetus following maternal injection, the latter at least apparently via the omphaloplacenta. The permeability to iron and phospate is extremely low. On the basis of these results and the selective transfer of certain dyestuffs, it appears that the shell membrane functions as a dialyzing membrane.
    Zusätzliches Material: 2 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051310105
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  • 73
    Digitale Medien
    Digitale Medien
    The fine structure of the spermatozoon of Pennaria tiarella (coelenterata) (1970)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 131 (1970), S. 117-129 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Spermatozoa of the hydroid Pennaria tiarella were examined with the electron microscope. The anterior region is characterized by the presence of 30-40 membrane-bounded vesicles which lie anterior to the nucleus. These vesicles are apparently derived from the Golgi apparatus.The nucleus is conical in shape with a protrusion at the anterior end. Posteriorly it is indented by four radially arranged mitochondria. Lying within the fossa formed by the mitochondria are proximal and distal (filament forming) centrioles. The distal centriole is characterized by nine centriole satellite projections which emanate from its matrix. The tubules of the distal centriole are continuous with the alpha filaments of the tail.The tails are typical 9 + 2 flagella with 9 peripheral doublet (or alpha) filaments surrounding two central (or beta) filaments.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051310108
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  • 74
    Digitale Medien
    Digitale Medien
    Salivary glands of heteromyid rodents, with a summary of the literature on rodent submandibular gland morphologyThis investigation was supported in part by U.S.P.H.S.-N.I.D.R. grant DE-02315 to Robert Gerstner and in part by NIH General Research Support grant FR 5332-08 to Ormond G. Mitchell. (1970)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 131 (1970), S. 179-193 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The principal parenchymal elements of the submandibular glands of the heteromyid rodents Dipodomys merriami, Perognathus longimembris, Perognathus fallax, Perognathus penicillatus and Perognathus baileyi consist of acini, granular tubules and striated ducts.Acinar cells of the four species of Perognathus are aniline blue, PAS (magenta) and Alcian blue (pH 2.5) positive and metachromatic with toluidine blue and safranin. The granules of the tubule cells are orthochromatic and react with aniline blue, orange G, the PAS reagent (deep pink) and the tryptophan indicator, xanthydrol. Acinar and tubule cells of D. merriami exhibit similar reactions except for the Alcian blue stain. Acinar cells of D. merriami do not react with Alcian blue.Submandibular glands of D. merriami exhibit a sexual dimorphism of the granular tubules. There is little observable difference between the sexes in the species of Perognathus but the ratio of granular tubules to acinar elements, the degree of hypertrophy of the tubules, and the amount of mucosubstance and protein (granules) contained in their cells are different in the four species studied.Since these desert rodents have similar habitats and habits, the differences observed between the two heteromyid subfamilies studied, as well as among the four members of a single subfamily, suggest that these are inherent species variations rather than variations of adaptation to environment.
    Zusätzliches Material: 4 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051310205
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  • 75
    Digitale Medien
    Digitale Medien
    Histology of the alimentary canal during the metamorphosis of Hyalophora cecropia (L.)Supported by grant AM-02818 from the National Institutes of Health. (1970)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 131 (1970), S. 277-299 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The histology of the alimentary canal is described for the last instar larva, pupa, and adult Hyalophora cecropia (L.). Particular attention is given to the changes occurring in the midgut during the larval-pupal transformation and in the hindgut during the pupal-adult transformation. Descriptions are made as to the nature of the imaginal rings at each end of the midgut and a new structure is described in the larval ileum. The formation of adult rectal pads is followed in detail.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051310304
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  • 76
    Digitale Medien
    Digitale Medien
    Masthead (1970)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 131 (1970) 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051310401
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  • 77
    Digitale Medien
    Digitale Medien
    Cuticle formation in the embryo of Drosophila melanogasterSupported by grant GM 10480 from the United States Public Health Service. (1970)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 131 (1970), S. 383-395 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: In Drosophila melanogaster embryos cuticle formation occurs between 12 and 16 hours of development at 25°C. The formation of the cuticulin and the protein epicuticular layers is simultaneous in the hypoderm, the tracheoblasts, and the fore- and hindgut cells. The cuticulin forms as a dual lamina, aggregating from granules secreted by the hypodermal cells. This is followed by the formation of a granular protein epicuticle and finally by the secretion of a mixed fibrous and granular endocuticle.All secretory cells are relatively simple in their ultrastructure. The secretory process is a membrane phenomenon, occurring at the tips of hypodermal microvillae on cells at the surface of the embryo and on those hypodermal cells lining the lumen of the fore- and hindgut. It also occurs along the entire surface of the tracheoblast lumen as well as on the outer surface of those cells which form exoskeletal chitinous setae. The process involves a specialization of the plasma membrane with the formation of secretory granules intracellularly beneath the membrane and the extrusion of these granules through the membrane to the outside where final cuticle formation occurs.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051310403
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  • 78
    Digitale Medien
    Digitale Medien
    Seasonal ovarian histology of the ovoviviparous iguanid lizard Sceloporus jarrovi copePart of a dissertation submitted to the University of Arizona Graduate School in partial fulfillment of the requirements for the Ph.D. degree in Zoology. (1970)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 132 (1970), S. 265-275 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Histological analyses of monthly collections of Sceloporus jarrovi ovaries are presented. The ovaries undergo a cycle in which yolk deposition occurs in September-October and is followed by ovulation in late November. One corpus luteum forms from each ruptured follicle and undergoes progressive cytoplasmic depletion until mid-June parturition, after which time rapid degeneration commences. Follicular atresia is common during the spring and absent during the summer and early fall. Granulosa cells play an active role in follicular atresia luteal cell formation, and may also be involved in yolk deposition.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051320303
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  • 79
    Digitale Medien
    Digitale Medien
    The fine structure of coelomocytes in the annelid Enchytraeus fragmentosusSupported by NIH grant AM 08632, U.S.P.H.S. The author gratefully acknowledges the advice of Dr. M. A. Williams, Dr. E. L. R. Stokstad and Dr. J. Vena. (1970)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 132 (1970), S. 335-351 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Two types of coelomocytes, the mucocyte and the phagocyte, occur in Enchytraeus fragmentosus. Other free cells observed within the coelomic cavity include chloragogen cells, peritoneal cells and some anucleate granular cells. Three forms of mucocytes occur and are believed to represent developmental stages. The first stage is one in which the mucous droplets are forming in the Golgi region. The second stage is a mature form, and the third stage is one in which the mucous droplets are being released. The phagocytes generally are quite large, and inclusions vary from recognizable portions of chloragogen cells to extremely small, electron-dense cytosomes. The origin of the coelomocytes could not be determined. Probable functions of coelomocytes are discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051320307
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  • 80
    Digitale Medien
    Digitale Medien
    Tooth development in Latimeria chalumnae (Smith) (1970)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 132 (1970), S. 377-387 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Tooth development in Latimeria was studied with the use of light microscopy, polarized light microscopy and microradiography.Teeth develop from cells derived directly from the basal layer of the oral epithelium in areas where teeth have been shed or are being resorbed. The teeth are composed of true enamel, orthodentine and pulp tissues. Attachment is accom-plished by bony attachment ankylosing the teeth to the basal bone of dental plates. The histologic picture of Latimeria teeth resembles more closely the teeth of tetrapods than those of most bony fish.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051320402
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  • 81
    Digitale Medien
    Digitale Medien
    Cell proliferation in vivo and in vitro in visceral organs of the adult newt, Triturus cristatus carnifex (1970)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 132 (1970), S. 453-459 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The mitotic and labelling incidence of intestine, liver, spleen and pancreas cells of Triturus cristatus carnifex adults kept at 15°C, 20°C, 25°C and 30°C were examined. Intestine mitotic and labelling incidences were highest at 25°C and lowest at 30°C. There was no significant difference between 15°C and 20°C. No such relationship could be shown for liver, spleen or pancreas, which had very much lower mitotic and labelling incidences. In culture, intestine mitotic and labelling incidences fell significantly within the first four hours, and maintained these low levels for the next five days. In contrast, liver mitotic and labelling incidences rose for 9-11 days, and then began to fall, while pancreas mitotic and labelling incidences reached peak values at day 5, and were kept in good condition for up to 14 days.
    Zusätzliches Material: 2 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051320406
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  • 82
    Digitale Medien
    Digitale Medien
    Studies on aggregation of embryonic cells: Initial cell adhesions and the formation of intercellular junctions (1970)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 132 (1970), S. 245-263 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The aggregation in vitro of embryonic neural retina cells was studied by electron microscopy with special emphasis on the reformation of intercellular junctions. The results show that (1) embryonic neural retina cells dissociated with trypsin retain morphological characteristics and polarity after dispersion into a suspension; (2) initial adhesions between the aggregating cells are nonspecific with respect to cell type and to the site of cell surface involved; (3) histogenetic associations in clusters of reaggregated cells appear within two hours after the start of aggregation. A hypothesis is presented that coated vesicles play a role in the formation of intercellular junctions.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051320302
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  • 83
    Digitale Medien
    Digitale Medien
    The lizard ear: ScincidaeFrom the Department of Psychology. This research was supported by grants from the National Institute of Neurological Diseases and Stroke. Public Health Service, and aided by a contract with the Office of Naval Research and by Higgins funds allotted to Princeton University. (1970)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 132 (1970), S. 277-292 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Observations on inner ear structure were made in five species of Scincidae, together with measurements of auditory sensitivity in terms of cochlear potentials. The basilar membrane and auditory papilla show a characteristic form, with considerable uniformity in dimensions except for a moderate expansion in the dorsal region and a more prominent one at the ventral end.A characteristic feature is the presence of a tectorial membrane that covers a large part of the surface of the medial limbus, but never leaves this surface and thus fails to make any contact with the auditory papilla. Hair-cell stimulation is achieved entirely through operation of the inertia principle (or equivalent principles) by means of a chain of sallets extending along most of the cochlea but giving way in the region of the ventral expansion to a single large body, the culmen papillae.The sensitivity varies in the five skinks studied from better than average to some-what below average in comparison with other lizard species. Thus an inertial (or inertia-like) system of hair-cell stimulation compares favorably with the tectorial membrane (restraint) system exhibited in the ears of most other lizards and all the higher animals.
    Zusätzliches Material: 14 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051320304
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  • 84
    Digitale Medien
    Digitale Medien
    Chemosensitive hairs in spiders (1970)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 132 (1970), S. 313-333 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Spiders possess curved, blunt-tipped hairs on all legs and palps, which differ in many details from the straight, sharp-pointed, tactile hairs: (1) the blunt tip is open to the outside, which can be demonstrated by high resolution microscopy and by the penetration of dyes; (2) the hair shaft has a double lumen which consists of a circular (tube) and a crescent shaped lumen; (3) this hair is innervated by two to three bipolar neurons whose dendrites enter the small tube, where they arborize into 16-20 branches. Multiple innervation and an open tip give strong evidence for a chemoreceptive function. Concluding from their position and distribution on the distal leg parts, a contact chemoreception is tentatively proposed. This interpretation is supported by the close structural analogy to the known contact chemoreceptors in insects. Observation of behavior indicates the importance of a contact chemoreceptor on spider legs. Other possible chemoreceptors in spiders which have been described previously by other authors are discussed.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051320306
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  • 85
    Digitale Medien
    Digitale Medien
    A histochemical study of the circumtesticular leydig cells of a teiid lizard, Cnemidophorus tigris (1970)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 132 (1970), S. 101-107 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Several oxidative enzymes in the testis of the teiid lizard Cnemidophorus tigris were studied histochemically. The cells of the circumtesticular sheath (Leydig cell tunic) are functionally equivalent to Leydig cells of the interstitium on the basis of similar histochemical reactions for the five enzyme systems studied. Both groups of cells were positive for 3β-hydroxysteroid dehydrogenase, 17β-hydroxysteroid dehydrogenase, NADH diaphorase, NADPH diaphorase, and glucose-6-phosphate dehydrogenase. These results support the hypothesis that the circumtesticular sheath has endocrine function as indicated by its vascularity and its ability to catalyze histochemical reactions involving steroid biosynthesis.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051320107
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  • 86
    Digitale Medien
    Digitale Medien
    Masthead (1970)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 132 (1970) 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051320201
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  • 87
    Digitale Medien
    Digitale Medien
    Ultrastructural studies on the corpora cardiaca-allata complex of the adult alfalfa weevil, Hypera posticaSupported by a post-doctoral fellowship GM28,152-01A1 to A.S.T. from the National Institutes of Health and GB-5445 from the National Science Foundation. (1970)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 132 (1970), S. 137-147 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The organization of the corpora cardiaca and corpora allata of the female alfalfa weevil, Hypera postica, generally parallels that reported for other insects with extrinsic neurosecretory axons, intrinsic neurosecretory cells, and interstitial or glial cells appearing in both glands.Connecting the brain with the cardiacum are the extrinsic neurosecretory axons containing granules between 600 and 2200 Å. Granules with a diameter of up to 4000 Å are found in the intrinsic secretory cells of the corpus cardiacum.From the lobed corpus cardiacum, axons extend along a short nerve trunk into the ovoid corpus allatum. A characteristic of this gland is the presence of a layer of axons, ensheathing most of the corpus allatum and situated beneath an external basement membrane. These axons are believed to have their origin in the protocerebral neurosecretory cells. Although the c. allatum is known to be engaged in the release of hormonally active material, the cytoplasmic organization does not strongly reflect such activity.The glands of the diapausing weevil appear similar to those of the active weevil with a reduction in cytoplasm and a consequent folding of the plasma membrane.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051320203
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  • 88
    Digitale Medien
    Digitale Medien
    The segmentation of the gnathobdellid leeches with special reference to the indian leech Hirudinaria and medicinal leech Hirudo (1970)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 132 (1970), S. 361-375 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Large number of annuli in Hirudinea are not true segments, and in the absence of spacious bodycavity and septa in adult no decision was taken regarding limit of a somite, until Gratiolet 1862 recognised a segment by colour marking, repetition of nephridial openings, and especially by the presence of segmental receptors, distinguishing first annulus of a segment. Whitman 1884 gave precision to these determinations and analyzed morphology of leeches to logical completeness. He recognised that though Hirudinaria and Hirudo have 102 body annuli and posterior sucker, true segments are only 26 plus 7.Castle ('00) and Moore ('00) proposed a new scheme of segmentation, with segmental receptor bearing annulus, as central annulus of a complete somite, with nerve ganglion, like that of other annelids, in center of a segment. They orientated everything roundabout the ganglion without noticing distorted fate of organ system.In this paper both the views are compared. Morphological and embryological studies reveal that the annulus bearing the segmental receptors in uniformly first annulus of all segments, including incomplete segments at the two extremities, with nerve ganglion in first annulus of the segment.Clitellum occupies three natural segments, IX, X, XI; crop caeca, nephridia, testis sacs, haemocoelomic channels and “rhomboidal figures” formed by ventrolaterals, all make a complete unit, well integrated in such segment. Conclusive evidence comes from the presence of septa at the level of each nerve ganglion in embryos of Hirudinaria. These observations corroborate Gratiolet and Whitman's view.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051320309
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  • 89
    Digitale Medien
    Digitale Medien
    The interphalangeal area of Rana pipiens: A light and electron microscopic study of the development of a fibrocartilaginous joint (symphysis)Grants in support of these investigations have been received from the U.S. Public Health Service, National Institute of Arthritis and Metabolic Diseases, grants AM-04599 and T1 AM-5285 from the Arthritis Foundation and from the Massachusetts Chapter of the Arthritis Foundation. (1970)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 130 (1970), S. 315-336 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The development of the distal interphalangeal joint in Rana pipiens hind limb was studied by light and electron microscopy. The joint was found to be a symphysis since the two articular surfaces originally capped by hyaline cartilage were separated by a joint area filled with fibrous connective tissue which ultimately was replaced by fibrocartilage. Ultrastructural studies demonstrated that the joint area development was divided into three phases. Phase I was concerned with the undifferentiated mesenchymal cells, phase II with fibroblastic and chondroblastic development, and phase III with the appearance of fibrocartilage. Changes in the cytoplasmic organelles of fibroblasts and chondroblasts, surrounding extracellular matrix, and factors related to extracellular matrix formation were described and discussed.
    Zusätzliches Material: 19 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051300305
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  • 90
    Digitale Medien
    Digitale Medien
    The fine structure of the trout blastoderm, Salvelinus fontinalis (Mitchill) (1970)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 130 (1970), S. 367-383 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The Speckled Trout blastoderm at the late high blastula stage is characterized by two different cell populations. The “light” blastomeres comprise one cell type while the “dark” and “medium” blastomeres appear to differ from one another only in degree and thus may be considered as the second type.“Dark” and “medium” blastomeres are irregular in shape, are located centrally and deep in the blastoderm, have an abundance of smooth endoplasmic reticulum with associated 520 Å glycogen particles and a single mitochondrial profile. The “light” blastomeres have randomly arranged glycogen particles in minimal quantities in contrast to the “medium” and “dark” blastomeres and in addition exhibit three mitochondrial profiles, which could however represent artifacts.It is postulated that in the Speckled Trout cellular differentiation has commenced by the third day of incubation at 10°C and that this is manifested visually by the appearance of two different cell populations; the more differentiated “dark” and “medium” blastomeres possibly destined to give rise to the hypoblast and the less differentiated “light” blastomeres.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051300308
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  • 91
    Digitale Medien
    Digitale Medien
    Histology of the neurosecretory system and the retrocerebral endocrine glands of the adult migratory grasshopper, Melanoplus sanguinipes (Fab.) (Orthoptera: Acrididae)Contribution 354, from the Research Station. (1970)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 130 (1970), S. 451-465 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Neurosecretory cells of only one type (A, sub type A2) are seen in adult Melanoplus. Two groups of about 400 cells each are located dorsally in the pars intercerebralis medialis; four cells are located deep within the protocerebrum. We found no neurosecretory cells in other parts of the central or sympathetic nervous systems. In about 10% of the specimens, there was marked asymmetry in the location of the dorsal cell groups, with both of these groups and their axons located in one lobe of the protocerebrum.The nervi corporis cardiaci 1 cross-over in the corpus cardiacum, with the result that material produced by neurosecretory cells on one side of the brain is transported along axons that undergo two chiasmata to the corpus cardiacum of the same side.Stainable secretory material could be traced clearly from the cerebral cells to the corpus cardiacum, and even into the oesophageal nerves from the hypocerebral ganglion. However, stainable neurosecretory material is never present in the corpus allatum or along any of the nerves to this gland.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051300405
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  • 92
    Digitale Medien
    Digitale Medien
    Masthead (1970)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 131 (1970) 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051310101
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  • 93
    Digitale Medien
    Digitale Medien
    The structure of the integument of the sea cucumber, Thyone briareusThis investigation was supported by U.S.P.H.S. grants AM 11908, AM 12129, and AM 05611 from the National Institute of Arthritis and Metabolic Diseases. (1970)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 131 (1970), S. 17-35 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The integument and podia of the sea cucumber Thyone briareus were examined by bright field and electron microscopy. The epidermal surface was found to be covered by an acellular, PAS positive cuticle which appeared to be secreted by the underlying epidermal cells. Although the superficial portion of the cuticle contains numerous fine filaments, their ultrastructure bears no resemblance to collagen fibers. The epidermal cells are widely spaced and have long apical processes that extend along the under surface of the cuticle forming a contiguous epithelium. The apical expansions of the epidermal cells are attached to one another by means of septate desmosomes which may run continuously around all epidermal cells. Special attachment structures within these apical expansions appear to bind the cuticle to the dermis. The epidermal cells and their apical expansions are separated from the dermis by an 800 Å thick basement membrane. Granule containing cells in the upper dermis send processes up to the cuticle where they are bound to the typical epidermal cells by septate desmosomes. The abundant membrane bound granules of the cells enter villous-like processes which pass through the cuticle. The function of these cells may be to produce an adhesive material on the podia or they may be pigment cells.The thick dermis consists of a superficial zone, containing largely ground substance; a middle or laminated zone containing laminae of collagen fibers arranged in an orthogonal fashion; and a hypodermis consisting largely of ground substance and reticular fibers. Fibroblasts are abundant in the superficial dermis and between the collagen laminae. Wandering coelomocytes, or morula cells, accumulate between the collagen laminae and in the hypodermis. They may also become an integral part of the epidermis by forming septate desmosomes with epidermal cells. Morula cells contain highly specialized spherules whose tinctorial properties and electron microscopic appearance suggest that they contain protein and mucopolysaccharide.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051310103
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  • 94
    Digitale Medien
    Digitale Medien
    Masthead (1970)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 131 (1970) 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051310201
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  • 95
    Digitale Medien
    Digitale Medien
    The growth and differentiation of the regenerating spinal cord of the lizard, Anolis carolinensisSupported by grants from the American Cancer Society, the National Institutes of Health and the Multiple Sclerosis Society. (1970)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 131 (1970), S. 131-151 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The present work describes the ultrastructure of the spinal cord in the regenerating tail of the lizard, Anolis. The distal growing region of the tail contains the advancing ependymal tube which is relatively devoid of axons but already contains channels between ependymal cell processes which anticipate their ingrowth. More proximally, fascicles of naked axons having their origin in the stump are present in the ependymal channels. Therefore, the pattern of fiber regeneration in the spinal cord is prescribed by the ependyma and not by the growing axons. Details of the ultrastructure of proximal, intermediate, and distal regions of the regenerate are reported. Particular attention is paid to the structure and differentiation of the ependymal cells and the relation of the ependyma to other glial cells, to nerve fibers, and to meningeal tissues.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051310202
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  • 96
    Digitale Medien
    Digitale Medien
    Structure of the integument of a fresh-water teleost, Bagarius bagarius (Ham.) (Sisoridae, pisces) (1970)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 130 (1970), S. 3-9 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The skin of Bagarius bagarius (Ham.) is devoid of scales but is rough due to the presence of numerous pentagonal epidermal elevations, which are separated by deep furrows at regular intervals. These elevated pentagonal regions of the epidermis are covered by dead cornified cells in the form of caps. As the old cap goes off a new one is formed by the death of the underlying epidermal cells. The middle layer of the epidermis is mainly composed of well defined polygonal cells. Their cytoplasm is granular in nature and give reactions for protein bound sulphydryl groups. The stratum germinativum is composed of two types of basal cells, the columnar cells and the spherical cells.The flask shaped mucous glands are restricted to the epidermal furrows and secrete either neutral or acidic mucopolysaccharides. Certain large specialysed granular cells are found in the epidermis which are grouped around the taste buds. These specialysed cells may be the photocytes.Two layers of the dermis can be distinguished - the relatively thin stratum laxum and the thick stratum compactum. Dermal papillae mainly support the taste buds. The pigment cells are arranged in two layers in the dermis.The subcutis is composed of loose connective tissues, richly infiltrated with the fat cells, nerves and blood capillaries.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051300103
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  • 97
    Digitale Medien
    Digitale Medien
    The lizard ear: Cordylus, platysaurus and GerrhosaurusFrom the Department of Psychology. This investigation was supported by grants from the National Institute of Neurological Diseases, Public Health Service, and was aided by a contract with the Office of Naval Research and by Higgins funds allotted to Princeton University. Permission is given for reproduction and use by the United States Government.Grateful acknowledgment is made of the assistance of Dr. Clarence J. McCoy, Jr., of the Carnegie Museum, Pittsburgh Pa., in identification of the specimens. The bodies of representative animals are deposited in the Museum and identified by the following numbers: C. warreni breyeri: CM47969 to 47974; C. vittifer: CM47962 to 47968; Platysaurus minor: CM47958 to 47961; Gerrhosaurus n. nigrolineatus: CM47548 and 47549. (1970)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 130 (1970), S. 37-55 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: In further consideration of the lizard ear, the fine structure of the cochlea has been investigated and related to auditory sensitivity in members of the family Cordylidae. The ear of this group of lizards is unusual in that a tectorial membrane is present only in a modified and seemingly vestigial form, and this membrane makes no connections with the auditory hair cells. These cells are provided instead with a series of sallets, small bodies extending in a single row through the dorsal and middle regions of the cochlea, where they rest upon the tips of the ciliary tufts and evidently bring about a stimulation of the hair cells because of their inertia. At the ventral end of the cochlea this line of sallets ends, and here is a single, relatively enormous structure, the culmen papillae, that serves a similar purpose for a large group of hair cells. Consideration is given to the manner of stimulation of the auditory sense cells in these species in relation to others with the usual arrangements involving connections between the ciliary tufts and a tectorial membrane.Included also is a study of a species of Gerrhosaurus, which some have included in the cordylid family and others have placed in a family of its own. The cochlear structure in this species is similar to that of the cordylids in many respects but differs in the ventral region, where instead of the culmen there is a heavy tectorial plate, similarly covering a large number of hair cells but connected to a tectorial membrane.The functioning of these ears is assessed in terms of the cochlear potentials, and is found to vary with species from better than average to excellent in comparison with other lizards investigated. The structural differentiation also is of fairly high degree, and hence it appears that ears without tectorial connections, or with such connections only in a limited region of the cochlea, can perform in a highly serviceable manner.
    Zusätzliches Material: 19 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051300106
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  • 98
    Digitale Medien
    Digitale Medien
    Post emergence maturation of the eye of the adult black carpet beetle, Attagenus megatoma (Fab.): An electron microscope studyUniversity of Georgia College of Agriculture Experiment Stations. Journal Paper No. 642, College Station, Athens.This research by the Agricultural Research Service, U. S. Department of Agriculture (Cooperative Agreement 12-14-100-9014(51)). (1970)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 130 (1970), S. 103-127 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The black carpet beetle, Attagenus megatoma (Fab.), has been reported to exhibit negative phototaxis immediately after emergence. In later adult life, after the period during which most oviposition has occurred, the beetles are found to be photopositive. The compound eyes of one-day-old (Post-emergence) and nine-day-old (Post-ovipositional) female beetles were studied by electron microscopy and a number of strong differences were found between eyes at the two ages. The corneal facets of one-day eyes had the form of convex-concave lenses, while those of nine-day beetles were double-convex lenses. The primary and secondary pigment cells of young eyes were large and contained much endoplasmic reticulum and little accessory pigment. In the older eyes the pigment cells were reduced and contained much pigment, the proportion of endoplasmic reticulum being greatly reduced by comparison with the one-day eye. The cross-sectional area of the rhabdom was greater in the older eye.The possible relationships between age-related changes in eye morphology and behavioral changes during the same period are discussed.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051300110
    Standort Signatur Erwartet Verfügbarkeit
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  • 99
    Digitale Medien
    Digitale Medien
    Seasonal reproductive activity in the testes and seminal vesicles of the catfish, Heteropneustes fossilis (Bloch)Supported by P. L. 480 grants 14-17-0007-154 and 14-17-0007-219 from the Bureau of Commercial Fisheries. U. S. Fish and Wildlife Service. (1970)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 130 (1970), S. 207-225 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: A seasonal study of the seminal vesicles in relation to that of the testes had been conducted in the catfish, H. fossilis. The annual reproductive cycle of the catfish has been divided into (i) Preparatory period (February-April), (ii) Prespawning period (May-June), (iii) Spawning period (July-August) and (iv) Postspawning period (September-January). Testes exhibit initiation of spermatogenesis in the mid-preparatory period, but significant increase in weight of the testes accompanied by active spermatogenesis occurs during the prespawning period. In the spawning period, the testes are maximally enlarged and their seminiferous tubules are packed with spermatozoa. Following spawning, the testes gradually regress in the postspawning period. The seminal vesicles show initiation of secretory activity during the preparatory period but their recrudescence lags behind that of the testes by about a month. The seminal vesicles attain maximum weight and secretory activity during the spawning period. Thereafter, the seminal vesicles regress precipitously and sooner than the testes.The histochemical and biochemical studies on the seminal vesicles indicate that the secretion contains mucoproteins, acid mucopolysaccharides, primary proteoses, besides traces of phospholipids and native proteins.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051300207
    Standort Signatur Erwartet Verfügbarkeit
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  • 100
    Digitale Medien
    Digitale Medien
    Inter-strain differences in the development of the pattern of periplasm distribution during cleavage of honeybee eggs (1970)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 130 (1970), S. 247-255 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: During cleavage of honeybee eggs two peaks arise in the longitudinal distribution pattern of the periplasm which coincide with the site of the differentiation center and the site of a mesodermal center. A very similar pattern is exhibited by the dorsal plasmstrip, a narrow band of thicker periplasm which is formed during cleavage along the dorsal midline of the egg. The present paper describes the development of the dorsal plasmstrips of two inbred strains of honeybees during early cleavage stages. Differences between the two strains reside in the total size of their dorsal plasmstrips and in the timing of the formation of the anterior peak which coincides with the site of the differentiation center. The bearing of these findings upon embryological studies is discussed.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051300209
    Standort Signatur Erwartet Verfügbarkeit
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