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  • 1
    Electronic Resource
    Electronic Resource
    The V-notch at weld lines in polystyrene injection moldings (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 931-936 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A major factor that weakens the weld line in injection moldings is the V-notch structure. Though the existence of a V-notch is well known, its depth variation with molding conditions has not been detailed. The aim of this paper is to clarify the V-notch structure and its effect on the strength of general purpose polystyrene injection moldings. A dog bone type tensile specimen with a weld line was molded under several molding conditions. The surface of the weld line was partially eliminated by cutting with a milling machine to seven levels of cut depth (Dc). As a result, the weld strength increased with Dc to about 50%. The relationship between the weld strength and Dc made it possible to determine the V-notch depth, which vas defined as the “depth of the weld line.” From these results, a hypothesis is proposed that the V-notch has a structure with a fine groove on the surface and a poorly bonded inner layer. This study considered the relationships among the weld strength, the depth of the weld line, and molding conditions.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760301508
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  • 2
    Electronic Resource
    Electronic Resource
    Histogenetic potential of rat hind-limb interdigital tissues prior to and during the onset of programmed cell death (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 236 (1993), S. 568-572 
    Details
    ISSN: 0003-276X
    Keywords: Interdigital mesoderm ; Programmed cell death ; Chondrogenesis ; Rat embryo ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The histogenetic potential of interdigital tissues isolated from the autopod of rat embryonic hind-limbs between 14.5 and 16.5 days was investigated. A wedge of tissue containing ectoderm and mesoderm was excised from between the developing digits and grafted beneath the kidney capsule of adult rats for two weeks. We have previously demonstrated that the renal capsule is an excellent site for permitting limb tissues to proliferate and differentiate (Chan et al.: J. Exp. Zool., 260:74-83, 1991). At 14.5 days, when cell death (revealed with neutral red stains) within the interdigital zone was limited to the apical ectodermal ridge (AER), the interdigital mesoderm was capable of developing into bone, cartilage, and loose connective tissue in the kidney. It was estimated that the skeletal elements occupied approximately 38% of the overall area of the grafts. In addition, the ectoderm was able to produce keratinized epithelium, hair follicles, and sebaceous glands. In 15.5 day autopod, necrosis was present both in the AER and the mesoderm between the AER and marginal sinus. Interdigital mesoderm obtained from this stage of development formed cartilage but not as extensively as that derived from 14.5 day autopod (4% as compared with 38%). Necrotic cells were present in all of the interdigital zones at 16.5 days. Ten explants were introduced into the kidney at this stage, but only 4 grafts were recovered after 2 weeks. In all cases, the explants did not produce cartilage. Only a small amount of keratinized epithelium and loose connective tissue was found. In summary the interdigital mesoderm has the potential to develop bone, cartilage, and loose connective tissue, but this ability is progressively lost during morphogenesis. © 1993 Wiley-Liss, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1092360317
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  • 3
    Electronic Resource
    Electronic Resource
    Diffusion of ethylene glycol accompanied by reactions in poly(ethylene terephthalate) melts (1992)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 30 (1992), S. 707-716 
    Details
    ISSN: 0887-6266
    Keywords: poly(ethylene terphthalate), diffusion of ethylene glycol in melts of ; diffusion coefficient of ethylene glycol in PET melts ; diffusion with chemical reaction of ethyleneglycol in PET melts ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Diffusion coefficients of ethylene glycol (EG) have been measured in poly(ethylene terephthlate) (PET) melts by a quartz-spring sorption apparatus. A simple mathematical model was developed to investigate the sorption behavior accompanied by chemical reactions of EG and PET at high temperatures. Diffusion coefficients are deduced from experimental data for an asymptotically thin sample in order to minimize the effects of reactions. The diffusion coefficient of EG is strongly dependent on the vapor pressure of EG and temperature but not on the molecular weight of PET in this experimental range (degree of polymerization 80-120). The diffusion coefficient of EG in PET melt at 265°C is 2.58 × 10-7 cm2/s at the limit of zero concentration of EG. The activation energy for diffusion is 38.4 kcal/gmol, and the heat of solution for sorption is -44.9 kcal/gmol. The concentrations of the volatile materials resulting from reactions in PET-EG system were analyzed with gas chromatography. In addition, a fit of the current model to experimental data yields frequency factors for the polymerization reaction (k1) and the acetaldehyde formation reaction (k2) to be 5.84 × 108 cm3/mol ċ min and 3.90 × 1011 min-1, respectively.
    Additional Material: 18 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1992.090300708
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  • 4
    Electronic Resource
    Electronic Resource
    Histochemical identification of primordial germ cells in diandric and digynic triploid mouse embryos (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 25 (1990), S. 364-368 
    Details
    ISSN: 1040-452X
    Keywords: Ploidy ; Alkaline phosphatase ; LT/Sv strain mice ; Nuclear micromanipulation ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Diandric and digynic triploid mouse embryos were isolated in the morning on day 10 of gestation. The embryos were separated from their extraembryonic membranes, and the latter were analysed cytogenetically by G-banding to establish the ploidy and sex chromosome constitution of these embryos. The diandric triploid embryos were produced by the technique of nuclear micromanipulation. Females were mated with male mice with a morphologically distinguishable “marker” chromosome to confirm the diandric status of these embryos. Digynic triploid and normal diploid embryos were isolated form LT/Sv strain females. These females spontaneously ovulate both primary and secondary oocytes, which are fertilisable and give rise to digynic triploid and normal diploid embryos, respectively. All the embryos were serially sectioned and processed in order to dmonstrate the presence of alkaline phosphatase enzyme activity. This histochemical technique allowed primordial germ cells to be readily recognised, due to their characteristic location, cellula morphology, and staining appearance. Primordial germ cells were found in all the embryos studied, being located within the visceral yolk sac, at the base of the allantois, and/or in association with the wall or mesentery of the hindgut. The total number of germ cells present was established in nine diandric triploids and in five digynic triploids. The findings presented here represent the first demonstration that primordial germ cells can differentiate in either diandric or digynic triploid mammalian embryos.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1080250409
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  • 5
    Electronic Resource
    Electronic Resource
    Studies of the effects of the organometallic coupling agents on adhesion of the glass fiber-BMI composites (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 45 (1992), S. 695-707 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: This work investigates the increase of adhesion between glass fiber and BMI. Five kinds of organometallic coupling agents of Ti, Zr, and Zr/Al are used to treat the fiber surface and then to reinforce BMI. A more efficient way is to mix the coupling agents directly into BMI and then reinforce by glass fiber. Then compare the adhesion of resulting composites, which are made by two methods described as above. As a result, the mechanical properties of the latter is slightly lower than the former. The Ti coupling agents are most effective, followed by Zr coupling agents and then Zr/Al coupling agents. Mixing Ti coupling agent directly into BMI, the degree of curing measured by DSC is 90%, the shear strength of the GFRP increases 31.9%, the flexural strength increases 30.8%, and the tensile strength increases 34.0%. Analyzing the chemical bonding by FT-IR, we found that choosing the organometallic coupling agent of type [RO-Ti (OX-R'NH2)3] and adding it to BMI can most effectively improve the adhesion. TGA shows that directly mixing coupling agent into BMI only changes a little of its thermal cracking temperature. Observed by SEM, we know that using coupling agent can promote adhesion between BMI and glass fiber.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1992.070450417
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  • 6
    Electronic Resource
    Electronic Resource
    Effects of the organometallic coupling agents on adhesion of the carbon fiber-BMI composites (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 45 (1992), S. 683-694 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: In order to increase the chemical bonding force between fiber and resin, several kinds of organometallic coupling agent (such as titanate, zirconate, and zircoaluminate) were chosen and added in the BMI resin formulation, which possess the same solvent system with those coupling agents. The DSC analysis technique was used to find the best curing condition, and TGA was used to investigate the thermal stability property of the best curing condition. For the purpose of analyzing the bonding structure, ESCA surface element analysis techniques was applied in this study. Beside that, the mechanical properties of tensile, flexural, and short-beam shear strengths were measured for the effect of adding coupling agents, and the SEM of fracture surfaces were taken to study the fractural analysis. The results showed that composites with the application of organometallic coupling agents of [RO-Ti(OX-R′NH2)3] structure in the treatment of BMI resin were highly thermal stable. Also, it was shown that the mechanical strengths of composites fabricated by pretreatment of the carbon fibers with coupling agents were higher than those fabricated by adding coupling agents in resins, but there was no obvious improvement of mechanical properties with higher concentration of coupling agents. However, the SEM showed that the adhesion between fiber and resin can actually be improved by adding proper amount of coupling agents in the BMI resin formulation.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1992.070450416
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  • 7
    Electronic Resource
    Electronic Resource
    Batch and semicontinuous emulsion copolymerization of vinylidene chloride and butyl methacrylate. II. Physical and mechanical properties of copolymer latex films (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 45 (1992), S. 2221-2234 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Vinylidene chloride (VDC)-butyl methacrylate (BMA) copolymer latex films of various compositions (83 : 17, 60 : 40, 33 : 67 in mol %), prepared by batch and semicontinuous processes, were investigated for their physical properties by infrared spectroscopy, 13C solidstate NMR spectroscopy, X-ray diffraction, solubility in various solvents, differential scanning calorimetry (DSC), and water vapor transmission rates (WVTR), and for their mechanical properties by dynamic mechanical spectroscopy (DMS), and tensile strength measurements. Semicontinuous latex films were found to be homogeneous in composition and amorphous in character. On the other hand, batch latex films containing high VDC monomer content were heterogeneous in composition and crystalline in character. These differences were found to reflect the effect of mode of monomer addition during the emulsion polymerization process, and correlated well to the results on kinetics, colloidal, and surface properties of the VDC-BMA copolymer latexes, as described in the first part of this study.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1992.070451218
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  • 8
    Electronic Resource
    Electronic Resource
    Batch and semicontinuous emulsion copolymerization of vinylidene chloride and butyl methacrylate. I. Kinetics in VDC-BMA emulsion polymerization and surface and colloidal properties of VDC-BMA latexes (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 45 (1992), S. 2207-2219 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Vinylidene chloride (VDC) - butyl methacrylate (BMA) comonomer mixtures with various composition (83 : 17, 60 : 40, 33 : 67 in mol %) were polymerized at 25°C using redox catalyst by batch and seeded semicontinuous emulsion copolymerization. The reactivity ratios determined in VDC (M1) - BMA (M2) emulsion copolymerization system were r1 = 0.22 and r2 = 2.41. Seven 35% solids (83 : 17 mol %) VDC-BMA copolymer latexes were prepared: one batch (G), one seeded batch (F), and 5 seeded semicontinuous polymerizations of 5 different monomer feed rates ranging from 0.27 (A) to 1.10 wt %/min (E). The kinetic studies of seeded semicontinuous polymerizations A-E showed that the rates of polymerizations (Rp) were controlled by the monomer addition rates (Ra). The conversion versus time curves for the polymerizations of 0 : 100-100 : 0 VDC-BMA mixtures by batch polymerization showed that the rate of polymerization (Rp) was a function of the number of particles, and that the rate of polymerization in a latex particle (Rpp) increased with increasing proportions of butyl methacrylate in the monomer mixture. All of the latexes had narrow particle size distributions. The greater particle number density in VDC polymerization and the greater water solubility of VDC suggest that the homogeneous nucleation mechanism is operative in VDC-BMA copolymerizations. The latex copolymers prepared by semicontinuous polymerization had lower number-and weight-average molecular weights than those of the corresponding batch copolymers, resulting from the monomer starvation occurring during the semicontinuous polymerization. The surface characterization study of the cleaned latexes showed that for the latexes by batch process, the surface charge density derived from strong-acid groups decreased with increasing proportion of VDC in the monomer mixture. On the other hand, for the latexes prepared by semicontinuous polymerization, the surface charge density derived from strong-acid groups did not depend on the monomer composition of the copolymers.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1992.070451217
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  • 9
    Electronic Resource
    Electronic Resource
    Dibutyryl cyclic adenosine monophosphate differentially regulates cell proliferation in low and high alkaline phosphatase SaOS-2 human osteosarcoma cells: Evidence for mediation by the insulin-like growth factor-II system (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 156 (1993), S. 462-468 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In the present study, we have sought to determine whether a given signal transduction pathway can have diverse effects on subpopulations of cells of a lineage depending upon the stage of differentiation. To test this hypothesis, we selected the cyclic adenosine monophosphate (cAMP) signal transduction pathway because of its recognized importance in mediating the actions of many hormones, e.g., parathyroid hormone which acts on the bone-forming cells, the osteoblasts. Subpopulations of human osteosarcoma SaOS-2 cells with low (LSaOS) and high (HSaOS) alkaline phosphatase (ALP) content were chosen as model systems for preosteoblasts (pre-OB) and osteoblasts (OB), respectively. Dibutyryl cyclic AMP (DBcAMP) treatment of serum free cultures produced a differential effect on the proliferation of LSaOS cells (40 ± 5% of control at 1 mM DBcAMP, P 〈 0.001) compared with HSaOS cells (no statistically significant effect). The finding supports the hypothesis. Next, we sought evidence for mediation, at least in part, by the insulin-like growth factor (IGF)-II regulatory system. We report that the basal expression of IGF-II, IGF binding protein (IGFBP)-3, and IGFBP-4 was higher in LSaOS cells than in HSaOS cells with the opposite true for type I IGF receptor. DBcAMP treatment of LSaOS cells decreased IGF-II and IGFBP-3 but increased IGFBP-4 and type I IGF receptor; no effect was observed for the type II IGF receptors. DBcAMP treatment of HSaOS cells had no detectable effect on IGF-II; IGFBP-3, or type I and type II IGF receptor expression; only IGFBP-4 expression increased with DBcAMP. These observations suggest that the differential regulation of cell proliferation by the cAMP signal transduction pathway may be mediated, at least in part, by the IGF-II regulatory system. © 1993 Wiley-Liss, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041560305
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  • 10
    Electronic Resource
    Electronic Resource
    Interactions of dimethyl sulfoxide and granulocyte-macrophage colony-stimulating factor on the cell cycle kinetics and phosphoproteins of G1-enriched HL-60 cells: Evidence of early effects on lamin B phosphorylation (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 146 (1991), S. 425-434 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We have found that GM-CSF and DMSO have antagonistic effects on the proliferation but not maturation of asynchronously growing HL-60 cells such that growth in the presence of both more closely resembles normal hematopoiesis (Brennan et al., J. Cell Physiol. 132:246, 1987). Studies were undertaken to determine whether or not the agents affected the same mitogenic pathway and locus in the cell cycle. HL-60 populations containing at least 90% G1 cells were obtained by centrifugal elutriation, exposed to 100 u/ml recombiniant human GM-CSF and/or 0-1.25% DMSO, and phosphoprotein changes quantified on autoradiograms of [32P]-orthophosphate-labeled cell proteins separated by giant 2-D gel electrophoresis. Results were correlated with (1) intracellular pH, determined by measurement of BCECF fluorescence; (2) [32P]-orthophosphate uptake; (3) cell cycle progression, determined by flow quantitation of DNA content in mithramycin or propidium iodide-stained cells; and (4) growth, determined by cell volume and concentration. GM-CSF stimulated and DMSO inhibited the GM-CSF-stimulated phosphorylation of 1 protein (∼65 kDa, p.i. 5.6) within 2 min of exposure. These effects were sustained through G1 not associated with changes in intracellular pH, and preceded similar antagonistic effects on phosphate uptake (15-30 minutes), cell volume change (16-24 hr), and cell concentration increase (28-32 hr). GM-CSF accelerated and DMSO inhibited G1 to S transit with the most marked antagonism observed in the second cycle following synch onization (28 to 40 hrs). Cell maturation (morphology, NBT reduction) was dominated by DMSO and not antagonized by GM-CSF. We have identified p65 as the nuclear intermediate filament protein, lamin B, on the basis of its locus on gels and its binding of a monoclonal antibody to intermediate filaments and antiserum to human lamin B on immunoblots. These studies suggest that at least part of the GM-CSF-DMSO antagonism is exerted through the same mitogenic pathway, that a major locus of cytokinetic effect is on G1 to S transit, and that nuclear envelope protein phosphorylation is an important early event.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041460313
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