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  • Polymer and Materials Science  (29)
  • Klinotaxis  (2)
  • ddc:650
  • 1
    Electronic Resource
    Electronic Resource
    Scanning motion, ocellar morphology and orientation mechanisms in the phototaxis of the nematode Mermis nigrescens (1990)
    Springer
    Journal of comparative physiology 167 (1990), S. 257-268 
    Details
    ISSN: 1432-1351
    Keywords: Scanning motion ; Shadowing ; Ocellus ; Mechanism ; Orientation ; Phototaxis ; Klinotaxis ; Photomovement ; Transverse phototaxis ; Nematode
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The putative ocellus of Mermis females consists of a hollow cylinder of dense hemoglobin pigmentation located in the anterior tip. The exact location of the photoreceptive nerve endings, however, is unknown. During phototaxis a continual bending or scanning motion of the head (anterior 2 mm) causes the orientation of the tip to swing about the direction of the source. By turning off (shuttering) the light source whenever the tip orientation was to one side of the source direction, the average orientation of the base of the head, and eventually the body orientation, was caused to be biased about 28° to the opposite side. Because the shuttering was synchronized with the scanning motion, the scanning motion must be involved in the maintenance of orientation to light. The direction of the bias rules out a two-signal comparison mechanism of orientation and demonstrates that a deviation of the tip from the source direction must decrease, rather than increase, the illumination of the photoreceptors. These findings, and the ocellar morphology, require that the photoreceptors be located inside the hollow tube of pigmentation where they can be shadowed by the pigment during deviations of the tip. Focusing by the curved anterior end should cause a similar modulation of the illumination at this location. The occasional episodes of transverse phototaxis can be explained by the leakiness of the pigment walls to transverse illumination. Analysis of the motion of the anterior in the presence and absence of shuttering indicates that the orientation of the base of the head, due to the motion of the neck, is controlled by the signals generated during one or more cycles of the scanning motion of the head. The orientation may be regulated by the phase relationship between the photoreceptor signal and putative proprioceptive signals that indicate the bending in the head.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00188118
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  • 2
    Electronic Resource
    Electronic Resource
    Components of phototaxis of the nematode Mermis nigrescens (1990)
    Springer
    Journal of comparative physiology 167 (1990), S. 245-255 
    Details
    ISSN: 1432-1351
    Keywords: Undulatory locomotion ; Scanning motion ; Directed turn ; Orientation ; Phototaxis ; Klinotaxis ; Photomovement ; Nematode
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The gravid females of Mermis are positively phototaxic at the time of their migration to egglaying sites in vegetation on which their grasshopper hosts feed. On a horizontal felt surface, segments of the path traced by the tail are oriented approximately towards a source of monochromatic light in the 350–540 nm region, but are not oriented at longer wavelengths and in the dark. The components of this phototaxis include locomotion by the posterior 4/5 of the body, orientational bending of the neck region while the anterior is held above the substrate, and a scanning motion (bending) of the head region (anterior 2 mm). Like other nematodes and snakes, propulsion is associated with posteriorly propagated body waves, but unlike other animals known, the waves tend to lie perpendicular to a felt surface, and unlike other nematodes, contact with the surface is on the female's ventral surface. The body waves are initiated by the motion of the anterior 1/5 (15 mm) of the body, the average orientation of which determines the path of the following 4/5. During phototaxis, the anterior tip is swung both sideways and vertically about the direction towards the light source. The tip motion is a result of a scanning motion of the head and a slower orientational bending of the neck. The base of the head appears to be actively directed towards the source by the bending of the neck. This behavior can resolve two light sources positioned 120° apart but not 90° apart. The scanning motion of the head is independent of neck orientation and appears to enhance the probability of discovering the direction of a new source. Discovery is followed by a directed turn of the base of the head towards the source which is initiated by the bending of the neck. Locomotion of the body follows the path of the anterior through the turn and phototaxis is thus initiated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00188117
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  • 3
    Electronic Resource
    Electronic Resource
    Graft copolymers of starch. I. Copolymerization of gelatinized wheat starch with acrylonitrile. Fractionation of copolymer and effect of solvent on copolymer compositionPresented in part at the 149th meeting of the American Chemical Society, Detroit, Michigan, April 1965.Prod. No. 1353 (1966)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 10 (1966), S. 929-937 
    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: The starch-polyacrylonitrile graft copolymer prepared from gelatinized wheat starch with ceric ammoninm nitrate as the initiator has been freed of ungrafted polyacrylonitrile and separated into fractions by extraction with dimethylformamide, γ-butyrolactone, and dimethyl sulfoxide. The copolymer fractions obtained differed appreciably in level of add-on, molecular weights of grafted chains, and grafting frequency. To determiue the molecular weights of grafted chains, the starch part of the copolymer was effectively removed by hydrolysis with α-amylase. It was necessary to dissolve or swell the polymer in dimethyl sulfoxide and freshly precipitate it by addition to water before enzymatic hydrolysis. In studying the effect of reaction medium on copolymer composition, there was less ungrafted homopolymer formed and a higher yield of graft copolymer possessing more frequent grafts with water than with aqueous dimethylformamide or aqueous ethylene glycol. Polymer solubility, the results of control polymerizations of acrylonitrile in the absence of starch, and the detection of glucose endgroups on the polyacrylonitrile liberated from the fractionated polymer by hydrolysis are presented as evidence that the copolymers obtained are true grafts rather thau intimate mixtures.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1966.070100610
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  • 4
    Electronic Resource
    Electronic Resource
    Graft copolymers of starch. III. Copolymerization of gelatinized wheat starch with acrylonitrile. Influence of chain modifiers on copolymer compositionProd. No. 1476 (1967)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 11 (1967), S. 457-463 
    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: A study was made of the influence of selected chain modifiers on both the molecular weight of grafted polyacrylonitrile and the grafting frequency of the starch-polyacrylo-nitrile graft copolymer. Gelatinized wheat starch was used with ceric ammonium nitrate as the initiator. The organic chain modifiers investigated were ethyl mercaptan, 1-dodecanethiol, methyl ethyl ketone, acetaldehyde, and chloroform. Sodium chromate, cupric bromide, cupric nitrate, cupric acetate, and cupric chloride were also tested as chain modifiers. In the presence of cupric chloride, there was a tenfold reduction in the molecular weight of grafted polyacrylonitrile; however, fewer chains were grafted to the starch backbone than were observed without cupric chloride.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1967.070110312
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  • 5
    Electronic Resource
    Electronic Resource
    Ceric-initiated polymerization onto polyacrylonitrile with carbohydrate end groups. Graft versus block copolymer formation (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 21 (1983), S. 2095-2100 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Starch-g-polyacrylonitrile (starch-g-PAN) copolymers were prepared by ceric ammonium nitrate initiation, and the major portion of the starch in these graft copolymers was then removed by acid hydrolysis to yield PAN with oligosaccharide end groups. Although these PAN-oligosaccharide samples reacted with methyl methacrylate in the presence of ceric ammonium nitrate, the resulting products were largely graft copolymers rather than the expected PAN-poly(methyl methacrylate) (PMMA) block copolymers. The following evidence is presented for a PAN-g-PMMA structure: (i) PAN without oligosaccharide end groups also produced a copolymer with methyl methacrylate under our reaction conditions. (ii) Starch-g-PAN (51 or 37% add-on) was a less reactive substrate toward ceric-initiated polymerization than PAN with oligosaccharide end groups. (iii) Low-add-on (18%) starch-g-PAN reacted with methyl methacrylate to give a final graft copolymer in which a large percentage of PMMA was grafted to the PAN component rather than to starch.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1983.170210719
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  • 6
    Electronic Resource
    Electronic Resource
    Graft copolymers by simultaneous 60Co-irradiation of starch, acrylamide, and N,N,N-trimethylaminoethyl methacrylate methyl sulfate (1974)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 18 (1974), S. 2205-2209 
    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: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1974.070180726
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  • 7
    Electronic Resource
    Electronic Resource
    Graft polymerization of acrylamide and 2-acrylamido-2-methylpropanesulfonic acid onto starch (1979)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 24 (1979), S. 2015-2023 
    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: Mixtures of acrylamide and 2-acrylamido-2-methylpropanesulfonic acid (AASO3H) were graft polymerized onto starch by cobalt-60 irradiation, and the water absorbency and water solubility of the resulting products were determined. The conversion of monomers to polymer was nearly quantitative when pregelatinized wheat starch and a water solution of the two monomers were simultaneously irradiated (simultaneous irradiation conditions). Products with high water absorbency were obtained with equal weights of starch and total monomers when acrylamide:AASO3H ratios ranged from 9:1 to 1:3. Water solubility of these polymers was over 50%. Neither of the two monomers gave absorbent polymers when graft polymerized individually onto starch. Although highly absorbent products were also obtained at a total monomer:starch ratio of 2:5, ratios of 1:5 and lower gave products with poor absorbency. Neutralization of AASO3H with sodium hydroxide before graft polymerization drastically reduced both the water solubility and absorbency of the final products. A reaction with granular starch was also carried out under simultaneous irradiation with a total monomer:starch ratio of 2:5 and with equal weights of the two monomers. Conversion of monomers to polymer was once again nearly quantitative. To obtain good water absorbency from this granular product, it was necessary to first neutralize the AASO3H portion with alkali, then disperse the polymer in hot water, and finally dry the resulting water dispersion. Graft copolymers with good water absorbency were also obtained by adding preirradiated starch to a water solution of acrylamide and AASO3H, although only partial conversions of monomers to polymer were realized. Selected products from the various graft polymerizations were fractionated by extraction with either water or a 1% solution of sodium chloride. The synthetic polymer content of the resulting fractions and the percentage of AASO3H in the synthetic portion of each polymer were determined. The Mn of some of the synthetic polymers was also determined after removal of carbohydrate by enzymatic hydrolysis.
    Additional Material: 5 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1979.070240909
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  • 8
    Electronic Resource
    Electronic Resource
    Polymerization of alkyl acrylates and alkyl methacrylates with starch (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 25 (1980), S. 2285-2294 
    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: A series of C4-C12 alkyl acrylates and methacrylates was polymerized with starch by irradiating starch-monomer mixtures with 60Co. Homopolymers were extracted with cyclohexane. The amounts of insoluble versus soluble synthetic polymer in polymerization run with alkyl acrylates varied less with the chain length of the alkyl substuent than in the polymerizations run with alkyl acrylates varied less with the chain length of the alkyl substituent than in the polymerizations run with alkyl methacrylates; and the poly(alkyl acrylate) contents of cyclohexane-insoluble fractions were all in the 38-45% range. Synthetic polymer contents of the products from butyl, hexyl, and decyl methacrylates were also close to this range. Octyl and lauryl methacrylate, however, gave high conversions to cyclohexane-soluble poly(alkyl methacrylate) along with little or no unextractable synthetic polymer in the starch-containing fractions. Poly(lauryl methacrylate) could be rendered insoluble by incorporating a small amount of tetramethylene glycol dimethacrylate in the polymerization mixture. In a series of polymerizations run with hexyl acrylate and hexyl methacrylate, lower irradiation doses led to more cyclohexane-soluble polymer and less synthetic polymer in the starch-containing fractions. Enzymatic digestion of starch-soluble polymer and less synthetic polymer in the starch-containing fractions. Enzymatic digestion of starch-containing polymers gave synthetic polymer fractions that were largely insoluble in cyclohexane. Crosslinking is, therefore, probably taking place during these polymerizations; however, we could not eliminate the possibility that reduced solubility was caused by small amounts of residual carbohydrate in these polymer fractions. Ceric ammonium nitrate-initiated polymerizations of butyl acrylate, hexyl acrylate, and butyl methacrylate with starch gave cyclohexane-insoluble polymers that contained 33-39% synthetic polymer. The higher alkyl acrylates and methacrylates produced little or no polymer under these conditions. Starch-containing fractions were tested as absorbents for hydrocarbons. Products prepared from decyl acrylate and lauryl acryle acrylate absorbed about 9 g of isooctane per 1 g of polymer, whereas the lowrer alkyl monomers gave polymers with lower absorbency.
    Additional Material: 5 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1980.070251015
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  • 9
    Electronic Resource
    Electronic Resource
    Saponification of wheat straw-g-polyacrylonitrile (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 33 (1987), S. 907-913 
    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: Wheat straw-g-polyacrylonitrile (PAN), containing 40% PAN, was saponified with sodium hydroxide and isolated under three sets of saponification and work-up conditions. Each reaction mixture was separated into a water-soluble and a water-insoluble fraction, which were individually analyzed for percentages (by weight) of synthetic polymer (saponified PAN), cellulose, hemicellulose, and lignin. Water solubles amounted to 14-24% of the total product and contained 70-74% synthetic polymer, the remainder being hemicellulose and lignin. Although water-insoluble fractions contained 52-54% saponified PAN, their water absorbencies were low (14-17 g H2O/g polymer). Treatment of these fractions with the enzyme cellulase converted 55-62% of the total cellulose of glucose.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1987.070330319
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  • 10
    Electronic Resource
    Electronic Resource
    Graft polymerization of acrylonitrile onto wheat straw (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 33 (1987), S. 899-906 
    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: Acrylonitrile was graft polymerized onto ground, water-washed wheat straw using Fe2+-H2O2 as initiator. Reaction conditions were selected to minimize homopolymer formation and maximize the amount of polyacrylonitrile (PAN) grafted to straw. Polymerizations typically yielded straw-g-PAN containing 30-35% PAN. A two-step fractionation scheme was developed for determining the relative amounts of PAN grafted to cellulose, hemicellulose, and lignin. This scheme involved (1) delignification of straw-g-PAN with sodium chlorite followed by removal of lignin-grafted PAN by extraction with dimethylformamide (DMF), and (2) hydrolysis of the hemicellulose component with 1 N trifluoroacetic acid followed by DMF extraction of hemicellulose-grafted PAN. Product remaining after these two treatments was assumed to be cellulose-g-PAN. When relative amounts of PAN grafted to cellulose, hemicellulose, and lignin were compared with relative percentages of these components present in wheat straw, the percentage of total PAN grafted to lignin was less than its relative percentage in straw, whereas that grafted to hemicellulose was considerably more. Although the use of Ce4+ as initiator gave little or no polymer with whole, water-washed straw, grafted polymerization occurred when delignified straw was used as substrate. Relative amounts of PAN grafted to cellulose and hemicellulose were not greatly different from those observed with Fe2+-H2O2 initiation onto whole straw.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1987.070330318
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