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  • Polymer and Materials Science  (7)
  • Cell elongation  (3)
  • Pisum sativum  (2)
  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Planta 150 (1980), S. 371-379 
    ISSN: 1432-2048
    Schlagwort(e): Auxin ; Cell elongation ; Epidermis peeling ; Fusicoccin ; Pisum
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The effects of peeling and wounding on the indole-3-acetic acid (IAA) and fusicoccin (FC) growth response of etiolated Pisum sativum L. cv. Alaska stem tissue were examined. Over a 5 h growth period, peeling was found to virtually eliminate the IAA response, but about 30% of the FC response remained. In contrast, unpeeled segments wounded with six vertical slits exhibited significant responses to both IAA and FC, indicating that peeling does not act by damaging the tissue. Microscopy showed that the epidermis was removed intact and that the underlying tissue was essentially undamaged. Neither the addition of 2% sucrose to the incubation medium nor the use of a range of IAA concentrations down to 10-8 M restored IAA-induced growth in peeled segments, suggesting that lack of osmotic solutes and supra-optimal uptake of IAA were not important factors over this time period. It is concluded that, although the possibility remains that peeling merely allows leakage of hydrogen ions into the medium, it seems more likely that peeling off the epidermis removes the auxin responsive tissue.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    ISSN: 1432-2048
    Schlagwort(e): Auxin ; Cell elongation ; Cytochalasin B ; Dictyosomes ; Secretion ; Triticum ; Zea
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Cytochalasin B (CB) inhibits the elongation growth of maize roots, and that of wheat coleoptile segments incubated in indolyl-3-acetic acid, by over 30% after a lag period of about 60 min. This long lag is not due to poor tissue penetration by the inhibitor, but seems to reflect a property of the process inhibited by CB. The only visible ultrastructural change accompanying growth inhibition is the accumulation of secretory vesicles in the vicinity of dictyosomes, which occurs between 90 and 300 min. However, a massive accumulation of vesicles is seen after 120 min in root cap cells which possess very active dictyosomes. The results indicate that CB does not inhibit elongation growth by interfering with cytoplasmic streaming. Instead, they indicate that the drug acts to inhibit the secretion of cell wall components at some stage after vesicle production, but prior to their transport.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    ISSN: 1615-6102
    Schlagwort(e): Dictyosomes ; Indoleacetic acid ; Pisum sativum ; Stereology
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary A quantitative analysis of electron micrographs showed that IAA treatment caused an initial rapid increase in the amount of dictyosome material in pea stem epidermal cells. The increase was detected within 15 minutes of auxin presentation and reached a maximum around 30 minutes. This was followed by a decrease, presumably due to an increased utilization of the organelle. The decrease involved a fall in the amount of dictyosome-derived vesicles and in the actual number of dictyosomes. The results are discussed in relation to similar observations on expanding cells of monocotyledonous plants.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 16 (1972), S. 1465-1477 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The bondability of the following polymers as a function of length of exposure to excited helium or oxygen was investigated: low-density polyethylene, high-density polyethylene (two types), poly(4-methyl-1-pentene), poly(vinyl fluoride), poly(vinylidene fluoride), FEP Teflon, poly(oxymethylene) copolymer, nylon 6, nylon 66, poly(ethylene terephthalate), and polystyrene. Generally, the bond strength increase rapidly initially and then remains nearly constant, perhaps decreasing in some cases at long exposure times. A method is presented for calculating bond strength-versus-exposure time curves. The calculated curves generally fit the data reasonably well. Polypropylene showed a rapid increase in bondability with exposure to excited oxygen. Helium was ineffective toward this polymer under normal conditions, but could produce good bond strength at higher temperatures.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 5
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Several studies of the influence of contact resistance on the measurement of thermal conductivity of polystyrene using a steady-state device are presented. In each case it is seen that, although this influence can perhaps be minimized, it cannot be eliminated as an experimental complication. A novel technique is then described which does eliminate entirely contact resistance as a variable, and this technique is shown to yield an unequivocal value of thermal conductivity.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 6
    ISSN: 1615-6102
    Schlagwort(e): Calcium ; Cell elongation ; Indole-3-acetic acid ; Pisum sativum ; Secretion
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The treatment of dark grown pea stem segments with chelators of divalent cations (EGTA, EDTA, CTC), various Ca2+ antagonists (LaCl3, A-23187, verapamil) and inhibitors of secretory processes (monensin, CB) reduced elongation in the presence of indole-3-acetic acid (IAA). Generally the inhibition increased with increasing concentrations of the substances. The timing of the responses can be correlated with maximum auxin-stimulated secretion of cell wall material. Examination of cell ultrastructure showed that changes in dictyosome activity could explain a reduced deposition of cell wall material and so cause inhibition of elongation. The inhibitors affected the morphology and vesiculation of the dictyosomes, and the appearance of the plasma membrane, ER and mitochondria in different ways. The most pronounced effects on ultrastructure resulted from monensin and LaCl3 treatments with the dictyosomes being most affected; large vesicles appeared in the cytoplasm. Less pronounced effects on cell structure were seen in EGTA, A-23187 and verapamil treated tissue. The effects on the dictyosomes are considered to be due to disturbances of Ca2+ and other ionic levels within the cells.
    Materialart: Digitale Medien
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  • 7
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 13 (1969), S. 2085-2096 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Polyethylene, polypropylene, poly(vinyl fluoride) (Tedlar), polystyrene, nylon 6, poly(ethylene terephthalate) (Mylar), polycarbonate, cellulose acetate butyrate, and a poly(oxymethylene) copolymer were treated with activated helium and with activated oxygen. Mechanical strengths of adhesive-bonded specimens prepared from treated and from untreated coupons were compared. Polyethylene (PE) and polypropylene (PP) showed the greatest increases in bond strength. Oxygen and helium were both effective with polyethylene, but polypropylene showed no improvement when treated with activated helium. The results with excited helium parallel the effects of ionizing radiation on these two polymers, as does the appearance of unsaturation bands in the infrared (965 cm-1 in PE, and 887 and 910 cm-1 in PP). Active nitrogen produced excellent bond strength with polyethylene but not with polypropylene. Of the remaining polymers examined, Tedlar, polystyrene, and nylon 6 showed the greatest improvement in bondability after treatment, and Mylar showed moderate improvement. Polycarbonate, cellulose acetate butyrate, and the poly(oxymethylene) copolymer gave approximately two-fold increases in lap-shear bond strength. In several cases, significant differences in response to time of treatment and type of excited gas were found.
    Zusätzliches Material: 6 Tab.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 8
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 57 (1962), S. 693-709 
    ISSN: 0022-3832
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Carbon blacks inhibit and retard free radical polymerization in bulk and solution. The mechanism of this is discussed in terms of the chemical groups present on the carbon surface. It is shown that the number of free radicals which react during the induction period (polymerization of styrene with AIBN) is much less than the number of quinone groups but of the same order of magnitude as the number of easily oxidizable groups. Inhibition by carbon black was also found in an emulsion polymerization system with cumene hydroperoxide as initiator (no reducing components). By use of highly active redox recipes, reasonable rates of polymerization were obtained at both 50°C. (sugar-iron-hydroperoxide recipe) and 5°C. (peroxide-polyamine recipe), with as much as 40 parts of black per 100 parts of monomers. In these systems, the carbon black was charged as an aqueous dispersion stabilized with Daxad 11; the latices were stable and showed evidence of association between some of the carbon black and some of the latex particles. The coagulated rubber stocks, when compounded and cured, gave properties closely similar to those of dry mixed stocks.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 9
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Letters 4 (1966), S. 463-465 
    ISSN: 0449-2986
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 10
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 19 (1981), S. 1357-1360 
    ISSN: 0360-6376
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: 1,3-Butadiene was polymerized anionically to polybutadiene which contained up to 100% 1,2-addition product. The atactic 100% 1,2-polybutadiene was prepared with n-butyllithium modified with bis piperidino ethane. The polymerization was done in hexane solvent at -5 to +20°C polymerization temperature.
    Zusätzliches Material: 2 Tab.
    Materialart: Digitale Medien
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