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  • Articles: DFG German National Licenses  (29)
  • Electronic Resource  (29)
  • Polymer and Materials Science  (26)
  • Cichlidae  (3)
  • 1
    Electronic Resource
    Electronic Resource
    Unique qualities and special problems of the African Great Lakes (1986)
    Springer
    Environmental biology of fishes 17 (1986), S. 161-183 
    Details
    ISSN: 1573-5133
    Keywords: Meromictic ; Evolution ; Diversity ; Cichlidae ; Productivity ; Aquatic reserves ; Flushing ; Pollution ; Fish introductions ; Lake development ; Limnology ; Fishery management ; Conservation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis The African Great Lakes consist of large, deep rift valley lakes (e.g. Malawi & Tanganyika) and shallower lakes between the Eastern and Western Rifts (e.g. Victoria). They are a group comparable in size to the North American Great Lakes, but are old. Most are seasonally thermally stratified, and wind is the decisive factor that determines the annual cycle of cooling and mixing. Lakes Tanganyika, Malawi and Kivu are meromictic, with deep relict hypolimnia. Large magnitudes and time scales of periodic internal motion, where these have been measured, appear unique among lakes. These lakes harbour the world's richest lacustrine fish faunas, and the family Cichlidae provides the supreme example of geographically circumscribed vertebrate evolution. The lakes provide a unique comparative series of natural laboratories for evolutionary studies. Primary production is generally high, but in the deeper lakes standing stocks of plankton and of small fish species are low. These pelagic populations are characterised by very high P:B ratios. The fisheries are productive and of socio-economic importance. Large-scale mechanised fishing is not compatible with the survival of the diverse fish communities. Cichlids appear especially vulnerable to unselective fishing. Aquatic reserves might offer a means of survival for at least some communities. Various pollution threats exist. Because water retention times are long, extremely long for some deep lakes, and flushing rates are low, the lakes are vulnerable to pollution which would be long-lasting. Introductions of alien fishes have mostly had undesirable or disastrous results. While the faunas are one of the significant natural heritages of mankind, their conservation must realistically be linked to the legitimate development of the lakes for the well-being of the people who live there. Scientific value alone will not protect the lakes. Just as survival of African terrestrial wildlife in extensive reserves depends heavily upon tourism, so also might the cichlid flocks in underwater reserves. Greater interest from the international scientific community is needed to further rational development and conservation of these great lakes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00002094
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    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Unique qualities and special problems of the African Great Lakes (1986)
    Springer
    Environmental biology of fishes 17 (1986), S. 161-183 
    Details
    ISSN: 1573-5133
    Keywords: Meromictic ; Evolution ; Diversity ; Cichlidae ; Productivity ; Aquatic reserves ; Flushing ; Pollution ; Fish introductions ; Lake development ; Limnology ; Fishery management ; Conservation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis The African Great Lakes consist of large, deep rift valley lakes (e.g. Malawi & Tanganyika) and shallower lakes between the Eastern and Western Rifts (e.g. Victoria). They are a group comparable in size to the North American Great Lakes, but are old. Most are seasonally thermally stratified, and wind is the decisive factor that determines the annual cycle of cooling and mixing. Lakes Tanganyika, Malawi and Kivu are meromictic, with deep relict hypolimnia. Large magnitudes and time scales of periodic internal motion, where these have been measured, appear unique among lakes. These lakes harbour the world's richest lacustrine fish faunas, and the family Cichlidae provides the supreme example of geographically circumscribed vertebrate evolution. The lakes provide a unique comparative series of natural laboratories for evolutionary studies. Primary production is generally high, but in the deeper lakes standing stocks of plankton and of small fish species are low. These pelagic populations are characterised by very high P:B ratios. The fisheries are productive and of socio-economic importance. Large-scale mechanised fishing is not compatible with the survival of the diverse fish communities. Cichlids appear especially vulnerable to unselective fishing. Aquatic reserves might offer a means of survival for at least some communities. Various pollution threats exist. Because water retention times are long, extremely long for some deep lakes, and flushing rates are low, the lakes are vulnerable to pollution which would be long-lasting. Introductions of alien fishes have mostly had undesirable or disastrous results. While the faunas are one of the significant natural heritages of mankind, their conservation must realistically be linked to the legitimate development of the lakes for the well-being of the people who live there. Scientific value alone will not protect the lakes. Just as survival of African terrestrial wildlife in extensive reserves depends heavily upon tourism, so also might the cichlid flocks in underwater reserves. Greater interest from the international scientific community is needed to further rational development and conservation of these great lakes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00698196
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Alternative reproductive behaviour in fishes, with particular reference toLepomis macrochira andPseudocrenilabrus philander (1990)
    Springer
    Environmental biology of fishes 28 (1990), S. 249-256 
    Details
    ISSN: 1573-5133
    Keywords: Cichlidae ; Centrarchidae ; Sneaker ; Cuckolder ; Satellite ; Territoriality ; Sunfish ; Courtship ; Leks ; Evolutionary strategies ; Life history
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis In the sunfish,Lepomis macrochira, males have discrete alternative reproductive life histories each with an equal potential for reproductive success. However, the alternative reproductive tactics of the cichlid,Pseudocrenilabrus philander, appear to have unequal payoffs. The adoption of either the territorial or the sneaking option in the cichlid fish is dictated by social conditions within the hierarchy. Consideration is given to Austad's questioning the value of models of Evolutionary Stable Strategies and to his proposed reclassification of alternative reproductive behaviours.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00751038
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Mechanism of accelerated photofading of thioether anthraquinone dyes in styrene butadiene resinsPresented, in part, at the IUPAC Photochemistry Symposium at Interlaken, Switzerland, July 1984. (1988)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 36 (1988), S. 1205-1219 
    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: Many anthraquinone dyes fade in visible light up to 100 times faster in styrene butadiene copolymers than in polyester resins or polystyrene. A mechanistic investigation of the photofading of 1,5-dihydroxy-2,6-diisobutyl-4-thiophenylanthraquinone has established that the dye sensitizes formation of singlet oxygen, a very reactive species, which attacks the double bonds in the styrene butadiene, resulting in extensive chain cleavage and peroxide formation. The major process is the oxidation of the polymer, and the dye fading is a minor process whereby the dye is apparently attacked by polymeric peroxides. The mechanism appears to be general for anthraquinone dyes, especially those with thioether, amino, hydroxy, or double-bond functionality. Unfortunately the fading is unaffected by most anticxidant stabilizers: the best result achieved was a doubling of half-life with 1 wt% Spinuvex A-36. This is still insufficient to give colored styrene butadiene copolymer resins the intrinsic dye stability available in other polymers, rendering styrene butadiene unsuitable for applications requiring high photostability of anthraquinone dyes.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1988.070360520
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  • 5
    Electronic Resource
    Electronic Resource
    The controlled flocculation of submicron emulsion particles. I. A three-step synthetic route to supermicron polymer particles (1996)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 34 (1996), S. 3061-3069 
    Details
    ISSN: 0887-624X
    Keywords: aggregation ; emulusion polymerization ; flocculation ; latex ; particles ; polymer ; size distribution ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The basic features of a three-step experimental process to produce supermicron polymer particles are described. First, a submicron emulsifier-free latex is prepared by a well-known technique. Second, the latex is aggregated by destabilizing with cetyl pyridinium chloride under constant stirring conditions, to yield roughly spherical clusters of 6-12 μ diameter. Third, the aggregates are stabilized with poly(vinyl alcohol) and internally coalesced by heating at or above the glass transition temperature. The final product particles have relatively smooth surfaces. Results are qualitatively interpreted in terms of a dynamic equilibrium where the aggregate size is determined by a balance between attractive interparticle potentials and stirring shear forces. Bimodal aggregate size distributions suggest the aggregate break-up mechanism may involve the erosion of individual latex particles and small fragments from the surface of aggregates. © 1996 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1996.866
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  • 6
    Electronic Resource
    Electronic Resource
    Dispersion polymerization of styrene in polar solvents. IV. Solvency control of particle size from hydroxypropyl cellulose stabilized polymerizationsPresented in part at the Canadian High Polymer Forum, Ottawa, August, 1987, and the NATO ASI on Polymer Colloids, Strasbourg, July, 1988; for Paper I of this series, see Ref. 1 (1990)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 28 (1990), S. 2485-2500 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Changing solvent has a dramatic effect on the outcome of HPC stabilized dispersion polymerization of styrene in polar solvents. In methoxyethanol/ethanol mixtures, particle size varies from essentially infinity for unstabilized reactions (below 30% ethanol) to about 3 microns in ethanol. In a series of n-alcohols, there was a maximum in particle size at intermediate chain length: particle size increased from 2 microns in methanol to 8.3 microns in pentanol, then decreased again to 1 micron in octadecanol. These results were rationalized in terms of the three-component Hansen solubility parameters. The largest particles were obtained in solvents with Hanson polarity and hydrogen bonding terms closest to HPC. The generality of the three-component solubility parameter approach was examined by reactions performed in eight mixed solvents with the same values of all three Hansen terms. Seven of the eight solvents gave particles of similar size and molecular weight. The two critical effects of solvent on both particle size and molecular weight appear to be: (a) the solubility properties of the grafted HPC-PS formed, and (b) the partitioning of monomer and initiator between solution and particle phases subsequent to nucleation.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1990.080280921
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    Paper (German National Licenses)
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  • 7
    Electronic Resource
    Electronic Resource
    Control of surfactant level in starve-fed emulsion polymerization. I. Sulfate-containing oligomers: Preparation and application as surfactant in emulsion polymerization (1995)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 1597-1606 
    Details
    ISSN: 0887-624X
    Keywords: emulsion polymerization ; surfactants ; oligomers ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: It is well known that the amount of surfactant must be carefully controlled during starve-fed emulsion polymerization processes. Too little surfactant leads to emulsion instability and coagulation, while too much surfactant leads to secondary particle formation. Although these relationships are qualitatively understood in the art, there is little quantitative basis to guide the synthetic chemist, especially in multistep starve-fed emulsion polymerization processes to make larger supermicron particles. We have developed a method, which will be described in a companion article, to control the surfactant level by monitoring the surface tension during polymerization. In order to quantitatively predict how much surfactant to add at any given time, one needs to know in advance the adsorption characteristics of the soap. Further complicating the matter is the formation of “in situ” or oligomeric surfactant during polymerization with aqueous initiators such as ammonium persulfate.This work demonstrates how to prepare surface-active oligomers and how to make latex particles using them as surfactant. First, we established the mass balance for the initiator-derived sulfate groups in seed latexes by conductometric, potentiometric, and iodometric titrations. Based on the characterization of seed latexes, a method for determining the effective sulfate concentration has been developed. When surface-active oligomers were used as the only surfactant, we obtained a series of monodisperse, supermicron copolymer latex particles with diameters up to 3.22 μm. This is a similar result to that obtained with a commercially made anionic surfactant. © 1995 John Wiley & Sons, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1995.080331006
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  • 8
    Electronic Resource
    Electronic Resource
    An application of arene-iron chemistry in the synthesis of a novel liquid crystalline polymer (1997)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 35 (1997), S. 447-453 
    Details
    ISSN: 0887-624X
    Keywords: polyether ; polyester ; aryl ether ; nucleophilic substitution ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Arene-iron chemistry was applied in the synthesis of a novel liquid crystalline polymer. The chemistry, which is based on iron cyclopentadienyl (FeCp) arene complexes, allows sequential nucleophilic substitution of the chlorides from 1,3-dichlorobenzene-FeCp complex and photolytic decomplexation of the products to afford asymmetrical aryl ethers. This methodology provides easy access to novel polyether-esters, and is potentially useful in the synthesis of various functional polyarylates. © 1997 John Wiley & Sons, Inc.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 9
    Electronic Resource
    Electronic Resource
    A comment on the paper “uniform polymer particles by dispersion polymerization in alcohol,” by C. M. Tseng, Y. Y. Lu, M. S. El-Aasser, and J. W. Vanderhoff [J. polym. sci. polym. chem. Ed. 24, 2995 (1986)]Presented, in part, at the NATO ASI on Polymer Colloids (Strasbourg, July 1988). This is Paper 5 in a series including Refs. 5-8 (1990)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 28 (1990), S. 2569-2574 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1990.080280928
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  • 10
    Electronic Resource
    Electronic Resource
    Use of 13C tags with specifically 15N-labeled DNA and RNA (1998)
    New York : Wiley-Blackwell
    Biopolymers 48 (1998), S. 57-63 
    Details
    ISSN: 0006-3525
    Keywords: 15N-nmr ; 13C-nmr ; specific labeling ; 13C tags ; nucleoside synthesis ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We describe methods to introduce 13C specifically to the C2 or C8 positions of 15N-multilabeled purines, thereby permitting “13C tagging” of all base nitrogens except the amino group of adenosine. These procedures permit the incorporation of two or more 15N-multilabeled monomers into a given DNA or RNA fragment, with and without appropriate 13C tags. This approach increases the number of 15N-nmr resonances that can be unambiguously distinguished and thus the amount of information from a single synthesis and a single nmr experiment. © 1998 John Wiley & Sons, Inc. Biopoly 48: 57-63, 1998
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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