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  • Artikel: DFG Deutsche Nationallizenzen  (13)
  • Digitale Medien  (13)
  • 1995-1999  (13)
  • 1
    Digitale Medien
    Digitale Medien
    Sedimentation in a large lake: the importance of fluctuations in water level (1997)
    Oxford UK : Blackwell Science Ltd
    Freshwater biology 37 (1997), S. 0 
    Details
    ISSN: 1365-2427
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: 1. A sediment trap study was conducted in the central basin of Lower Lough Erne, Northern Ireland.2. The material caught was low in organic matter, ash weight was 77% of dry weight on average.3. Mass deposition of material was shown to be correlated with lake water level. When lake water level fell or rose above the middle range, the amount of material caught by the trap increased markedly. The effect was exaggerated by an unusually dry summer in 1995 which caused abnormally low water levels in the lake.4. Comparison of Erne data with Windermere shows similar deposition rate of many substances, but the deposition rate of iron is thirteen times higher in Erne than in Windermere, and iron made up 39% of the ash weight in the Erne trap data.5. Only 17% of the silica removed from the water column during diatom growth was recovered in the trap over the same time period.6. Trap data are compared with historical data for sediment deposition and the implications of sediment focusing are discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1046/j.1365-2427.1997.00186.x
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  • 2
    Digitale Medien
    Digitale Medien
    Isospectral sets for akns systems on the unit interval with generalized periodic boundary conditions (1996)
    Springer
    Geometric and functional analysis 6 (1996), S. 1-27 
    Details
    ISSN: 1420-8970
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik
    Notizen: Abstract We analyze isospectral sets of potentials associated with generalized periodic boundary conditionsB inSL (2, ℝ) for the 2 ×2AKNS systems on the unit interval. WhenB is a rotation we get the usual periodic case. WhenB is not a rotation isospectral sets are cylindrical real analytic submanifolds ofL ℝ 2 ([0, 1])2 ×SL(2, ℝ) and their sections for fixed boundary conditions are real analytic submanifolds ofL ℝ 2 ([0, 1])2.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02246765
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  • 3
    Digitale Medien
    Digitale Medien
    Origin and identification of bacteria which produce kairomones in the frass ofAcrolepiopsis assectella (Lep., Hyponomeutoidea) (1995)
    Springer
    Cellular and molecular life sciences 51 (1995), S. 1073-1075 
    Details
    ISSN: 1420-9071
    Schlagwort(e): Kairomone production ; bacteria ; Klebsiella oxytoca ; sulphur volatiles ; frass ; parasitoid ; Diadromus pulchellus ; leek moth
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract The volatiles used by the parasitoidDiadromus pulchellus to find its host, the leek moth, are produced by the bacteria developing in the frass of the host larvae. The origin and the nature of these bacteria were investigated. Samples were taken from healthy leeks and from infested leeks in the field, as well as from the frass of larvae reared in the laboratory either on the host plant or on an artificial diet. The various species of bacteria identified were cultured in the presence of precursors of leek sulphur volatiles and their volatile emissions were analysed.Klebsiella oxytoca and variousBacillus, common decomposers of plant matter, were the principal species producing active volatiles which were alkyl disulphides.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01946919
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  • 4
    Digitale Medien
    Digitale Medien
    Characterization of particle size and size distribution of multi-sized polymer lattices by centrifugation plus quasielastic light scattering (1997)
    Springer
    Colloid & polymer science 275 (1997), S. 986-991 
    Details
    ISSN: 1435-1536
    Schlagwort(e): Key words Characterization ; particle size distribution ; multi-sized ; latex ; centrifuge ; quasielastic light scattering
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Notizen: Abstract  A method for characterizing the particle size and size distribution of multi-sized polymer lattices was developed by combining quasielastic light scattering (QELS) with a centrifuge. Lattices were first fractionated by centrifugation and the different populations of particles were separated in successive steps. The size of these particles was measured by QELS, and the mass fraction of the particles was determined gravimetrically. The particle size and size distribution of several blends of monodisperse lattices and two industrial multi-sized lattices have been measured by this method. The results show that the particle sizes obtained using this method are in good agreement with the expected particle diameters, and that the relative amounts of the different groups of particles in the blends can be accurately determined. The efficiency of centrifuge-QELS was also confirmed by comparison with other techniques such as transmission electron microscopy (TEM), QELS, field-flow fractionation (FFF) and capillary hydrodynamic fractionation (CHDF). However, this method is not suited for the analysis of continuous, broad distributions or mixtures with a high number of different populations. It is better suited for distributions with a small number of families of particles, and then can be used for preparative propose on a laboratory scale.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s003960050176
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  • 5
    Digitale Medien
    Digitale Medien
    Surfactants with transfer agent properties (transurfs) in styrene emulsion polymerization (1995)
    Springer
    Colloid & polymer science 273 (1995), S. 999-1007 
    Details
    ISSN: 1435-1536
    Schlagwort(e): Surfactants ; polystyrene ; emulsion polymerization ; amphiphilic thiol ; transfer agents
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Notizen: Abstract Styrene emulsion polymerization has been carried out at 70°C using 2–2′ Azobis (2 methyl, N-(2 hydroxyethyl) propionamide as initiator and thiol-ended surfactants (I) HS-C11 H22- (OCH2 CH2) n OH withn from 17 to 90 units. The kinetics of monomer conversion, the evolution of particle size, particle size distribution, molecular weight, and molecular weight distribution have been studied. After washing the final latex, the incorporation yield of the surfactant moieties in the particles has been measured. Most of the experiments have been carried out in batch; complementary experiments used semi batch or seeded process. In some experiments the two functions of transfer agent and surfactants have been decoupled using either dodecylmercaptan (oil soluble) or thioglycolic acid (water soluble) as transfer agent and the bromine ended precursor of (I) as surfactant. The discussion of the results is chiefly oriented towards both the molecular weight distribution and the incorporation of the surfactant to the latex.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00657666
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  • 6
    Digitale Medien
    Digitale Medien
    Rheology of concentrated multi-sized poly(St/BA/MMA) latices (1998)
    Springer
    Colloid & polymer science 276 (1998), S. 305-312 
    Details
    ISSN: 1435-1536
    Schlagwort(e): Key words Rheology ; multi-sized ; high solid content ; latex
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Notizen: Abstract  Four monodisperse latices with particle size of 75, 135, 340 and 477 nm were synthesized. The rheo-logical properties of mixture of the monodisperse latices were inves-tigated as a function of blending ratio, and compared with those of multi-modal latices, in a range of shear rate from 0.2 to 100 s-1. The maximum packing (highest solid contents) was observed at a weight fraction 80% of large particles with respect to total solids contents for both bimodal and trimodal latices, and the lowest viscosity was obtained when the ratio of large to medium to small particles was approximately 80/10/10 (by wt.). It was also demonstrated that this minimum in the viscosity is not strongly dependent on the actual size of each kind of particles present in the multimodal latices.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s003960050244
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  • 7
    Digitale Medien
    Digitale Medien
    Contributions to defining the rate constants for the homo- and copolymerisation of butyl acrylate and vinyl acetate (1995)
    Springer
    Polymer bulletin 34 (1995), S. 361-368 
    Details
    ISSN: 1436-2449
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Summary Free radical homo- and copolymerisations of vinyl acetate and butyl acrylate were carried out in solution. Initial differences in data from homopolymerisation experiments lead us to investigate the influence of an eventual oxygen inhibition on the observed rate of polymerisation. A kinetic study at 70 °C was carried out both with and without a nitrogen purge. A decrease in the rate of polymerisation in the second instance was attributed to the presence of dissolved oxygen in the solution. Estimates of the apparent inhibition constant from different experiments are used to model both homopolymerisation and copolymerisation with vinyl acetate. The importance of taking this phenomenon into account during kinetic studies is demonstrated.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00294156
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  • 8
    Digitale Medien
    Digitale Medien
    The genus Malassezia with description of four new species (1996)
    Springer
    Antonie van Leeuwenhoek 69 (1996), S. 337-355 
    Details
    ISSN: 1572-9699
    Schlagwort(e): Malassezia ; lipophilic yeasts ; taxonomy ; morphology ; physiology ; ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The genus Malassezia has been revised using morphology, ultrastructure, physiology and molecular biology. As a result the genus has been enlarged to include seven species comprising the three former taxa M. furfur, M. pachydermatis and M. sympodialis, and four new taxa M. globosa, M. obtusa, M. restricta and M. slooffiae. The descriptions of all the species include morphology of the colonies and of the cells, together with ultrastructural details. The physiological properties studied were the poesence of catalase, the tolerance of 37°C and the ability to utilize certain concentrations of Tween 20, 40, 60 and 80 as a source of lipid in a simple medium. Information is given for each of the taxa on mole % GC and also the rRNA sequence from the comparison previously described for the genus.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00399623
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  • 9
    Digitale Medien
    Digitale Medien
    Study of the thermal decomposition of potassium persulfate by potentiometry and capillary electrophoresis (1996)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 34 (1996), S. 1271-1281 
    Details
    ISSN: 0887-624X
    Schlagwort(e): potassium persulfate ; decomposition ; soap-emulsified systems ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Two methods of analysis, potentiometry and capillary electrophoresis, were used to study the decomposition of potassium persulfate (KPS) in aqueous solutions. The experiments were carried out in a glass reactor equipped with continuous control of temperature and pH during the reaction. The effect of the pH on the decomposition of KPS was investigated. The rate of KPS decomposition in the presence of a variety of additives (surfactants, inhibitor, monomer-like molecules, and monomers), which are used in emulsion polymerization recipes, was also studied over the temperature range of interest. The rate of disappearance of the persulfate ion was greatly increased in the presence of hydroquinone, but changed very little in the presence of surfactants. © 1996 John Wiley & Sons, Inc.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
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  • 10
    Digitale Medien
    Digitale Medien
    Efficiency of mercaptan chain transfer agents in emulsion copolymerizations. I. Influence on kinetics and microstructure. Modeling of radical desorption (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 157-168 
    Details
    ISSN: 0887-624X
    Schlagwort(e): emulsion polymerization ; reaction calorimetry ; chain transfer agents ; kinetics ; radical desorption ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The effect of chain transfer agents (CTA) on the emulsion copolymerization of styrene and butyl acrylate was studied in a bench scale 7 L reactor. On-line estimates of conversion were obtained through the joint use of calorimetric measurements and fast gravimetric data. Off-line measurements of partial conversions, molecular weight distribution (MWD), glass transition temperature (Tg), and particle diameter were also performed in order to investigate the effect of two mercaptans (tert-butanethiol and n-dodecanethiol) on both the kinetics of the polymerization process and the microstructure-dependent properties of the copolymer. The obtained experimental results were interpreted in terms of radical desorption and diffusive limitations of the CTA between the oil droplets and the particles. A model has been derived to compute the kinetic constants, the number of radicals per particle, and both the GPC/SEC diagrams and DSC thermograms related to MWD and Tg measurements, respectively. Several batch and semibatch examples are proposed to show that these important variables are satisfactorily fit by the model. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 157-168, 1998
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
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