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  • Polymer and Materials Science  (9)
  • green manure  (4)
  • 1
    Electronic Resource
    Electronic Resource
    The fate of clover-derived nitrogen (15N) during decomposition under field conditions: Effects of liming and fertilization (1988)
    Springer
    Plant and soil 111 (1988), S. 121-126 
    Details
    ISSN: 1573-5036
    Keywords: barley ; decomposition ; fertilization ; green manure ; liming ; N-budget ; N-release ; 15N ; red clover
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Red clover material labelled with15N was confined in mesh bags and buried into microplots in October at two field sites in Sourthern Finland. The soils (Kettula silt loam and Långvik loam) contained in the microplots were previously limed and fertilized with PK (N was given in next May) in different combinations. The following May the microplots were sown with barley and after the barley had been harvested (that August) soil samples and the mesh bags were removed. The crop, mesh bags and soil were then analysed for15N content. The soil treatments did not affect the release of clover N from the mesh bags and only slightly its retention in Kettula silt loam. The dry mass of barley obtained responded strongly to the different soil treatments. In comparison, the uptake of clover N by the barley varied much less; in Kettula silt loam a 1.6 fold increase in barley dry mass did not affect its content of clover N (12–13% of input) and in Långvik loam a ten fold increase in barley dry mass yield corresponded to a three fold increase of the content of clover N (5–16%). The total recovery of clover N (clover N in soil+mesh bags+barley harvest) was almost independent of the soil treatment; in Kettula silt loam and Långvik loam being respectively 52–56% and 71–85% of the input.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02182045
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  • 2
    Electronic Resource
    Electronic Resource
    The fate of nitrogen (15N) released from different plant materials during decomposition under field conditions (1988)
    Springer
    Plant and soil 105 (1988), S. 133-139 
    Details
    ISSN: 1573-5036
    Keywords: field bean ; green manure ; mesh bag ; N cycling ; N loss ; N-15 ; red clover ; subterranean clover ; timothy ; white clover
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Release of N, retention in soil, availability to a subsequent crop and total recovery of N derived from different15N-labelled plant materials decomposing in soil was investigated in two field experiments. In the first experiment five different plant species (white clover, red clover, subterranean clover, field bean and timothy) and in the second subterranean clover of different maturity (2,3 and 4 months old) were buried in mesh bags in the soil and allowed to decompose for 10 and 4 months, respectively. Most of the N released from the decaying plant materials was retained in the soil (27–46% of input). The subsequent crop (barley) took up 6–25% of input. The uptake correlated with the amount of N released from the decomposing material (r=0.936*, I experiment). Similar amounts of subterranean clover N were taken up by barley regardless to whether the material was buried in soil in the previous autumn or just before sowing of the crop. At the end of the experiments, the total recovery of the introduced plant-derived N varied between 89 and 102%. The results present evidence that the ability of the soil to retain plant-derived N is strong in comparison with the ability of the subsequent crop and different loss mechanisms to remove it.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02371151
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  • 3
    Electronic Resource
    Electronic Resource
    Leaching of subterranean clover-derived N from a loam soil (1987)
    Springer
    Plant and soil 102 (1987), S. 185-191 
    Details
    ISSN: 1573-5036
    Keywords: green manure ; leaching ; loam ; nitrogen ; nitrogen budget ; N-15 ; subterranean clover
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The leaching of subterranean clover-derived N (15N) was investigated in a laboratory and a field experiment. In both experiments 30 cm i.d. ×50cm soil columns were used. In the laboratory experiment the clover material was buried in the soil in mesh bags, and leaching of clover-derived N was compared to leaching of added NH 4 + −N and NO 3 − −N over a period of 75 days at 20°C. During that time 75% of the clover-N was released from the mesh bags and 17% of the clover-N, 50% of the NH 4 + −N and 70% of the NO 3 − −N was leached through the soil column. In the field experiment 6 lysimeters and 7 control microplots were constructed. The clover material was buried in soil (to the soil of two control microplots within mesh bags) in October. During one year 2% of the added clover-N was leached. This was despite a release of 65% of the N from the mesh bag contents and despite a 26% loss of the clover-derived N in total from the controls.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02370701
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  • 4
    Electronic Resource
    Electronic Resource
    The fate of clover-derived nitrogen (15N) during decomposition under field conditions: Effects of soil type (1988)
    Springer
    Plant and soil 105 (1988), S. 141-147 
    Details
    ISSN: 1573-5036
    Keywords: barley ; decomposition ; green manure ; N-budget ; N-release ; N-15 ; soil type ; subterranean clover
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Seven soils were collected from different field sites in Southern Finland and placed into microplots confined in PVC-cylinders (30 cm i.d. × 50 cm). Subterranean clover material labelled with15N, contained in mesh bags, was buried into the microplots in October, and the plots were sown with barley the following May. The mesh bags were removed and soil samples taken immediately after the barley harvest. The crop, mesh bags and soil were then analysed for15N content. The soil type affected release of clover N from the mesh bags and its retention in soil only slightly; at the end of the experiment the mesh bags contained 30–38% and the soil (0–45 cm) 28–37% of the clover N input. The uptake of clover N by the barley crop varied from 11 to 20% and correlated best with the soil electrical conductivity (r=0.820*). The total recovery of clover-derived N varied from 72 to 92%.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02371152
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  • 5
    Electronic Resource
    Electronic Resource
    Statistics of polyfunctional polycondensates formed under restrictions (1978)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 179 (1978), S. 1821-1835 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The scattering behaviour and the critical conditions where gelation takes place have been calculated for polycondensates formed under constraints. The general model includes fully random and stringently restricted reactions as limiting cases. Also polycondensates of glycerine-type monomers are included as special cases. The particle scattering factors of the f-functional random polycondensates differ remarkably from those polycondensates formed under strict constraints. The former show a Kratky plot of a simple curve, independent of the magnitude of the molecular weight and the number of functional groups, and the curve approaches a constant asymptote of u2·Pz(u)=3, the latter exhibits a maximum at u2=6 which becomes more pronounced with increasing molecular weight, (u2 = 〈S2〉zh2, with h, the value of the scattering vector). The scattering curves of the polycondensates formed under weak constraints show at low molecular weights the same behaviour as those formed under stringent constraints, but approach the behaviour of random polycondensates at large molecular weights. The scattering curves of the glycerine-type polycondensates show no deviations in shape from random polycondensates.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1978.021790717
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  • 6
    Electronic Resource
    Electronic Resource
    Photoinitiated degradation of poly(diacetylene)s in solution by random chain scission (1984)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 185 (1984), S. 1727-1737 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Poly(diacetylene)s dissolved in common organic solvents undergo random chain scission, if irradiated by UV-light. The pure polymers and their solutions are, however, stable, if they are photoirradiated within the main-absorption band of the polymer backbone. The usual triplet sensitizers, especially in the presence of oxygen, and radical donors such as 2,2′-azoisobutyronitrile (AIBN) enhance the rate of photodegradation. Suitable dyes are able to sensitize the chain-scission in the visible regions as well. Random chain scission occurs also in the dark, but only at temperatures above room temperature and is enhanced by the addition of radical-donors, e.g. AIBN. A mechanism of chain scission, induced by the attack of a radical to a multiple bond of the polyconjugated backbone of the polymer is proposed.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1984.021850819
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  • 7
    Electronic Resource
    Electronic Resource
    Crystallinity and thermal behaviour of trans-poly(1-octenylene)Dedicated to Prof. H.-J. Cantow on the occasion of his 65th birthday (1988)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 189 (1988), S. 2823-2837 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The commercially available poly(1-octenylene) Vestenamer® formed by the metathetic polymerization of cyclooctene with a tungsten catalyst, is highly crystalline at room temperature; it shows specific properties as a blend component, thus favourably influencing the processing characteristics and the final product quality. Differential scanning calorimetry, infrared and torsion pendulum experiments indicate that the melting temperature and the degree of crystallinity depend on the concentration of trans double bonds, on their distribution along the polymer chain as well as on the sample history. The formation of crosslinks induced by very intensive UV irradiation of 100 μm thin films leads to a reduction of the melting temperature and the crystallinity. A correlation between stiffness (shear modulus G′) and crystallinity was found for samples with varying amounts of trans double bonds.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1988.021891210
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  • 8
    Electronic Resource
    Electronic Resource
    Gradient high performance liquid chromatography of polymers, 2.Part 1: cf. 21. Characterization of block copolymers of decyl and methyl methacrylate synthesized via group transfer polymerizationDedicated to Prof. Dr. W. Burchard on the occasion of his 60th birthdayPresented in parts at “Makromolekulares Kolloquium”, Freiburg, Germany 1989. (1990)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 191 (1990), S. 2151-2172 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Statistical and block copolymers of decyl (DMA) and methyl methacrylate (MMA) were synthesized via group transfer polymerization (GTP) and characterized by size exclusion chromatography (SEC) and gradient HPLC. For HPLC a normal-phase solvent gradient of isooctane and THF was used; the chromatograms were recorded by evaporative light scattering detection (ELSD). The block copolymers were shown to contain substantial amounts of precursor homopolymer by gradient elution, even in those cases where SEC furnished a perfectly monomodal molecular weight distribution (MWD). Comparison of the respective HPLC elution characteristics demonstrated that block copolymers are more strongly retained than statistical copolymers of identical composition. Whereas the latter are eluted according to chemical composition, the elution of the block copolymers seems to be controlled by the length of the poly(MMA) block.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1990.021910917
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  • 9
    Electronic Resource
    Electronic Resource
    Small-angle x-ray scattering studies of fibrin film: Comparisons of fine and coarse films prepared with thrombin and ancrod (1989)
    New York : Wiley-Blackwell
    Biopolymers 28 (1989), S. 1011-1018 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Measurements of small-angle x-ray scattering have been made on films prepared from fine and coarse (i.e., formed at high and low, respectively, pH and ionic strength) clots of bovine fibrin by osmotic shrinkage or compression in one dimension. Intensity profiles were obtained with pinhole geometry on films stretched up to a stretch ratio of 1.43. In unstretched coarse films, repeat spacings were seen at about 245, 120, and 77-80 Å. These peaks can probably be identified with the first, second, and third orders of the well-known fibrin repeat of 225 Å. In unstretched fine films, only the 77-80 Å spacing was seen. In this case, the first two orders may be weak because the half-staggered arrangement of monomer units giving rise to the 225 Å reflection is not reinforced by lateral aggregation of protofibrils; the third order may be strong since the molecular subdomains appear to divide the repeat roughly into thirds. After stretching, the 77-80 Å spacing persisted in the meridional direction but almost disappeared in the equatorial. Experiments on unstretched films prepared with ancrod substituted for thrombin gave similar results.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360280508
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  • 10
    Electronic Resource
    Electronic Resource
    Stress relaxation in fine fibrin films: Comparison of films prepared with thrombin and ancrod (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 2311-2323 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Measurements of stress relaxation in uniaxial extension have been made on fibrin film prepared from fine bovine fibrin clots (i.e., clots in which there is minimal lateral aggregation of protofibrils), both ligated and unligated, and polymerized with both thrombin and ancrod, plasticized with either aqueous buffer or glycerol. The stress 100 s after imposition of strain was approximately proportional to In λ, where λ is the stretch ratio. Ligated thrombin films showed comparatively little relaxation over a period of one day and almost complete recovery after release of stress. In unligated thrombin films, there was substantial relaxation in two stages, as previously observed for coarse films, and substantial irrecoverable deformation. The extent of relaxation and the proportion of strain that was irrecoverable increased with the magnitude of the strain. In ancrod films (unligated), there was much more relaxation (stress decaying by as much as a factor of 10) and much more irrecoverable deformation (about 70% of the initial deformation); these results did not depend on the magnitude of the strain. When an ancrod film was released after relaxation and submitted to a second stretch, the extent of the second relaxation was much less. These observations are discussed in relation to the structure of fine films and possible mechanisms for relaxation and irrecoverable deformation.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360231113
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