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  • 1
    Electronic Resource
    Electronic Resource
    The developmental fate of dictyostelium discoideum cells depends greatly on the cell-cycle position at the onset of starvation
    Amsterdam : Elsevier
    Cell Differentiation 22 (1987), S. 11-18 
    Details
    ISSN: 0045-6039
    Keywords: Cell adhesion ; Cell cycle ; Cell sorting ; Chemotaxis ; Development ; Dictyostelium discoideum
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0045-6039(87)90409-X
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  • 2
    Electronic Resource
    Electronic Resource
    Development of an autophagic system in differentiating cells of the cellular slime moldDictyostelium discoideum (1981)
    Springer
    Protoplasma 108 (1981), S. 55-69 
    Details
    ISSN: 1615-6102
    Keywords: Acid phosphatase ; Autophagic vacuole ; Cytochemistry ; Dictyostelium discoideum ; Differentiation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Changes in an autophagic system during differentiation of cells ofDictyostelium discoideum, NC-4 were studied under light and electron microscopes, and it was demonstrated cytochemically that acid phosphatase was almost exclusively localized in food and autophagic vacuoles. Autophagic vacuoles first appeared during formation of loose aggregates, coupled with the defecation of food vacuoles. Autophagic vacuoles seem to originate from flat sacs which segregate parts of the cytoplasm. No acid phosphatase was detected in the vacuoles when first formed, but activity appeared later probably due to fusion with Golgi-like vesicles. When starved cells were not allowed to aggregate due to a low cell density, they formed no autophagic vacuoles but retained many food vacuoles. This indicates that the formation of autophagic vacuoles is not simply due to starvation, but to cell interaction mediated by cell contact. Autophagic vacuoles containing acid phosphatase rapidly increased in number in all cells in the early stage of aggregation. After papillae formed, however, they selectively decreased in the prespore cells, but developed further and grew larger in the prestalk cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01276883
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  • 3
    Electronic Resource
    Electronic Resource
    Development of prespore vacuoles inDictyostelium cells differentiating in a liquid shake culture (1984)
    Springer
    Protoplasma 123 (1984), S. 152-159 
    Details
    ISSN: 1615-6102
    Keywords: Cellular slime mold ; Dictyostelium discoideum ; Development ; Electronmicroscopy ; Golgi apparatus ; Prespore vacuole
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary When shaken in a glucose-albumin-cyclic AMP medium, dissociated aggregative cells form small clumps in which prespore cells differentiate fairly synchronously (Okamoto 1981). Formation of prespore vacuoles (PSVs) in differentiating prespore cells was examined in these culture conditions, by electronmicroscopy and immunocytochemistry. After 6 hours of culture, a typical Golgi apparatus composed of vesicles and stacked flat cisternae develops near the nucleus. FITC-conjugated antispore serum stains a crescent-shaped region in the cells which seems to correspond to the Golgi area. After 9 hours, flat sacs which contain electron dense lining membrane similar to that of PSVs appear alongside Golgi cisternae. Later, partially and fully round PSVs are observed in this region, suggesting that flat sacs round up to become mature PSVs. After 12 hours, as mature PSVs increase in number, they become dispersed throughout the cytoplasm and a typical Golgi apparatus with cisternae disappears. When cultured in a medium devoid of cyclic AMP, cells develop neither Golgi cisternae nor PSVs. These results strongly suggest that PSVs form from Golgi cisternae.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01283585
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  • 4
    Electronic Resource
    Electronic Resource
    Gas permeation in polyethersulfone (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 33 (1987), S. 1823-1828 
    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
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1987.070330533
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  • 5
    Electronic Resource
    Electronic Resource
    Helix-Coil transition of plasmid dna by adiabatic differential scanning microcalorimetry (1988)
    New York : Wiley-Blackwell
    Biopolymers 27 (1988), S. 1917-1925 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Adiabatic differential scanning microcalorimetry, which provides curves of the heat capacity vs temperature, was carried out for the DNA of plasmid pJL3-TB5 (5277 base pairs in length). The calorimetry curve shows nine peaks ranging from 81 to 96°C in 1 × SSC buffer at a heating rate of 0.25°C, due to the stepwise helix-coil transition of the DNA along the molecular chain. The theoretical melting curve, which can be constructed by calculation from the entire nucleotide sequence of the plasmid DNA by the helix-coil transition theory, is then compared with the calorimetry curve. The two curves resemble each other remarkably well, particularly when a parameter for the methylated adenine residues at GATC sites by Dam methylase is used appropriately. This allows us to assign each peak in the calorimetry curve to the melting of the respective regions of the plasmid DNA sequence. The local stability of the helix-coil transition along the DNA chain is closely related to the functional regions coded by pJL3-TB5, such as genes, transcriptional promoters, and particular sites generated by recombination of two different sequences in vivo and in vitro.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360271206
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  • 6
    Electronic Resource
    Electronic Resource
    Determination of dual-mode sorption and mobility parameters from permeation experiments (1986)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 24 (1986), S. 121-131 
    Details
    ISSN: 0887-6266
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The precise pressure dependence of apparent diffusion and permeation coefficients was measured by using a microcomputer system for collecting and treating permeation data for CO2 in glassy poly(ethylene terephthalate) below 1 atm between 15 and 40°C. The partial immobilization model was used to determine the dual-mode sorption and mobility parameters. The curves calculated with these parameters were in excellent agreement with experimental data. These parameters were also compared with sorption parameters obtained from measurements at 30°C. There was a small difference between the values of the parameters obtained from these permeation data and those from sorption data which we had previously obtained. Relations between this difference and the method of determination of the parameters are discussed.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1986.180240113
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  • 7
    Electronic Resource
    Electronic Resource
    Effect of antiplasticization on gas sorption and transport. I. Polysulfone (1987)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 25 (1987), S. 957-980 
    Details
    ISSN: 0887-6266
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The addition of tricresyl phosphate, N-phenyl-2-naphthylamine, and 4,4′-dichlorodiphenyl sulfone to polysulfone causes changes in thermal and mechanical properties of the glassy mixtures associated with antiplasticization, i.e., reduction in glass transition temperature and increase in stiffness. These changes are also found to be accompanied by reductions in sorption of carbon dioxide and the permeability coefficients for helium, carbon dioxide, and methane at low diluent concentrations with reversal of these trends at higher levels as also occurs for the mechanical properties. Detailed analyses of data for carbon dioxide are given in terms of the dual sorption and mobility models often used for glassy polymers. The mobility for gas transport was found to decrease with diluent addition. The major cause for the decreased sorption is the reduction in glass transition temperature accompanying addition of the diluents. The changes in transport behavior approximately parallel the changes in mechanical behavior. These trends are not even qualitatively correlated with estimates of the excess volume changes associated with addition of the diluents to polysulfone.
    Additional Material: 19 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1987.090250501
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  • 8
    Electronic Resource
    Electronic Resource
    Effect of antiplasticization on gas sorption and transport. II. Poly(phenylene oxide) (1987)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 25 (1987), S. 981-1003 
    Details
    ISSN: 0887-6266
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The propensity for various diluents to cause antiplasticization of poly(phenylene oxide) was examined and compared with similar responses for polysufone. Of the diluents used, none resulted in significant stiffening of poly(phenylene oxide) at 35°C relative to what was observed for polysulfone in an earlier paper. However, these diluents did cause substantial reduction in gas sorption levels and permeability coefficients. The latter is consequently a more sensitive indicator of changes in molecular motions of glassy polymers caused by diluents. The permeability response of adding low molecular weight diluents is compared with that of adding a high molecular weight polymer, polystyrene, to poly(phenylene oxide). The data were analyzed and interpreted along lines used in the companion paper for polysulfone.
    Additional Material: 19 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1987.090250502
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  • 9
    Electronic Resource
    Electronic Resource
    Effect of antiplasticization on gas sorption and transport. III. Free volume interpretation (1987)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 25 (1987), S. 1005-1016 
    Details
    ISSN: 0887-6266
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Previous papers have shown that antiplasticization of polysulfone and poly(phenylene oxide) by low molecular weight diluents is accompanied by substantial reductions in permeability to gases like helium, carbon dioxide, and methane because of reduced mobility in the glass. These effects are not explained even qualitatively by the extent of volume contraction on mixing for these mixtures. However, as shown here, a simple free volume treatment provides an excellent correlation of these effects. Free volume was computed from measured specific volume and an estimate of the volume at the absolute zero of temperature of the material from a group contribution method. Application of this approach to the mechanical stiffening associated with antiplasticization is suggested. The basis and limitations of this analysis are discussed.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1987.090250503
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  • 10
    Electronic Resource
    Electronic Resource
    Separation of water-ethanol by pervaporation through polyion complex composite membranePaper presented at 3rd International Conference on Pervaporation Processes in the Chemical Industry, September 1922, Nancy, France. (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 42 (1991), S. 3229-3239 
    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: For the purpose of separating alcohol-water mixtures by the use of the pervaporation technique, new composite membranes composed of polyion complexes (PIC) as a separating layer were developed. The polyion complex structure, consisting of polyacrylic acid (PAA) and polycation, provided excellent permeation rate and selectivity. Among the polycations, ionenes, which have quaternary ammonium groups in the backbone chain, were effective in giving membranes of higher permselectivities. High selectivity of PIC membranes was observed at high ethanol concentration regions in the feed mixture. For the azeotropic mixture of water/ethanol (95 wt % EtOH) at 60°C, the PAA-based PIC membrane had the following separation properties: separation factor ∼ 3,500 and permeation rate ∼ 1.6 kg/m2 h.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1991.070421216
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