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  • Polymer and Materials Science  (23)
  • Analytical Chemistry and Spectroscopy  (7)
  • Zea mays  (4)
  • Astrophysics
  • 1985-1989  (34)
  • 1
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Meßergebnisse zur Adsorption von Tannin auf hydrophiler Baumwolle bei unterschiedlichen Temperaturen werden vorgestellt. Die Thermodynamik des Adsorptionsgleichgewichtes des Tannins wird untersucht. Mit zunehmender Temperatur nimmt die Menge des adsorbierten Tannins ab. Das Adsorptionsgleichgewicht des Tannins läßt sich durch eine Adsorptionsisotherme nach Freundlich beschreiben. Weiterhin wurde das Strömungspotential des Systems Cellulose/Tannin/Rhodamin-B-Lösung untersucht, und der Einfluß der Beize auf die elektrokinetischen Eigenschaften der mit einem kationischen Farbstoff gefärbten Cellulosefasern wurde analysiert. Das Verhalten des elektrokinetischen Potentials konnte im wesentlichen durch die Bildung von H-Brücken zwischen den phenolischen Hydroxylgruppen des Tannins und den Carboxygruppen der Cellulose sowie durch die elektrostatische Anziehung zwischen dem Farbstoff-Kation und der Faseroberfläche erklärt werden.
    Notes: Data on the adsorption of tannic acid on the hydrophilic cotton at different temperatures are presented. The thermodynamics of the adsorption equilibria of tannic acid is investigated, and it is established that the increase in temperature decreases the amount of tannic acid adsorbed. The adsorption equilibria of tannic acid are described by the Freundlich adsorption isotherm. Also, an experimental investigation on streaming potentials of cellulose/tannic acid/Rhodamine B solutions system is described and the effect of the mordant on the electrokinetic properties of cellulosic fibres dyed with a cationic dye is analyzed. The behaviour of the electrokinetic potential could be explained mainly by the H-bonds formed between the phenolic hydroxy groups of tannic acid and the carboxy groups of cellulose and by the electrostatic attraction between the dye cation and the surface of the fibre.
    Additional Material: 9 Ill.
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  • 2
    ISSN: 1432-0789
    Keywords: A. chroococcum ; Seed inoculation ; Zea mays ; Acetylene reduction assay ; Yield response ; Associative N2 fixation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Inoculated and non-inoculated seedlings of Zea mays were grown in agricultural soils under aseptic and non-sterile conditions. Acetylene reduction activity and microbial counts were determined after 7 and 30 days of growth. Irrespective of the soil type Azotobacter spp. were commonly isolated under maize cultivation. Inoculation of agricultural soils with a suspension of A. chroococcum led to an increase in Azotobacter numbers, although this effect diminished with time. Nitrogenase activity was detected on maize roots and increased in response to the inoculation with A. chroococcum, showing that this associative growth could be of primary importance for the plant. The results of assays for acetylene reduction activity indicated that the nitrogenase activity was associated only with the root systems.
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  • 3
    ISSN: 1432-0789
    Keywords: A. chroococcum ; Zea mays ; Yield response ; Fertilizer N ; Inoculation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Field experiments were conducted during 1985 and 1986 to examine the effect of Azotobacter chroococcum on the grain yield of maize. Application of 40 kg N ha−1 plus A. chroococcum caused a significant increase in maize yield. Azotobacter inoculation was more efficient at lower doses (40 kg N ha−1) than at high doses (80 kg N ha−1) of urea.
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  • 4
    ISSN: 1573-5036
    Keywords: Azotobacter chroococcum ; phytohormones ; root exudates ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Growth ofAzotobacter chroococcum in N-free medium was stimulated in the presence of maize root exudates. Our results show that the production of auxins, gibberellins and cytokinins were significantly stimulated when maize root exudates from 7 to 30 d old plants were added to the culture media.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Euphytica 40 (1989), S. 245-251 
    ISSN: 1573-5060
    Keywords: Zea mays ; maize ; multilocation trials ; yield stability ; principal coordinates analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Principal coordinates analysis was used to determine the yield stability of some CIMMYT maize populations (Zea mays L.) measured by the performance of the varieties selected from them. The varieties included in this study were derived from subtropical of early and intermediate maturity maize populations. The analyses included grain yield data from international trials conducted from 1979 to 1983. Results show that varieties selected from the population Blanco Subtropical were stable in low yielding sites. Of the populations considered in this study, Amarillo Bajio and ETO-Illinois produced a greater number of varieties that give stable yields under both favourable and unfavourable environmental conditions. Some selections based on multilocational data showed good stability across years in both low and high yielding sites; however, across location varieties were not always more stable than specific site selections. Varieties formed in Tlaltizapan (Mexico), and Chuquisaca (Bolivia) were very stable in other regions.
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  • 6
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The apparent viscosity η of semi-dilute solutions of cellulose nitrate in ethyl acetate was measured as a function of shear rate at 20°C by rotational viscometry. The mass concentration c of the solutions was chosen such that the product between c and the intrinsic viscosity was 8 〈 c · [η] 〈 22, lying in the range of viscosity-average degrees of polymerization covered by the employed samples 550 〈 DPη 〈 7600. The experimental flow curves were interpreted in terms of Graessley's theory for non-Newtonian flow of polydisperse polymers. The polydispersities derived for five individual samples according to the theory of Graessley were used for calculating the resulting theoretical curves belonging to four binary mixtures each between two of them. The reasonable good agreement between calculated and experimental reduced flow curves of blends indicates consistency of the theory when applied to the present system of a semi-rigid polymer. This and other results point to a flow behaviour of semi-rigid cellulose nitrate being similar to that of linear flexible polymers.
    Additional Material: 3 Ill.
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  • 7
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The oligomerization of oxetane (trimethylene oxide) initiated by sulfuric acid in methylene chloride in the presence of 1,3-propanediol (trimethylene glycol) leads to the formation of α-hydro-ω-hydroxyoligo(oxytrimethylene)s. The effect of adding different amounts of trimethylene glycol was studied, and the dimer, 3,3′-oxydipropanol, could be isolated. Polymers from dimethyl terephthalate and 3,3′-oxydipropanol and copolymers from 1,3-propanediol, 3,3′-oxydipropanol and dimethyl terephthalate were synthesized. The influence of the chemical structure on their thermal transitions was analyzed.
    Additional Material: 2 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 34 (1987), S. 1959-1966 
    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: A significant reduction on the time for thermal crystallization of Bisphenol-A polycarbonate has been achieved by means of a previous crystallization step of the polymer in acetone, followed by a capillary extrusion processing at temperatures above its melting range (230-280°C). The crystallinity of PC was corroborated qualitatively by means of WAXS and quantitatively by means of DSC. The acetone-crystallized polymer showed higher values of dynamic viscosity than its amorphous counterpart. Such difference decreased with the increase of the test temperature and disappeared at 280°C. The degree of crystallinity of thermally crystallized PC increased with the decrease of the capillary extrusion temperature of the acetone-crystallized material. It is inferred that the time-temperature-dependent long range molecular diffusion necessary for the total melting of the crystal fractions could not take place entirely for the short times employed (≈ 4 min), allowing the extruded polymer to behave as a self-nucleated material.
    Additional Material: 6 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 25 (1987), S. 1449-1450 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 10
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Letters Edition 25 (1987), S. 431-435 
    ISSN: 0887-6258
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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