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  • Chemistry  (51)
  • 2,4-D adsorption  (2)
  • Daphnia  (2)
  • 1990-1994  (32)
  • 1980-1984  (23)
  • 1
    Electronic Resource
    Electronic Resource
    The effect of size at birth, maturation threshold and genetic differences on the life-history of Daphnia magna (1991)
    Springer
    Oecologia 86 (1991), S. 243-250 
    Details
    ISSN: 1432-1939
    Keywords: Daphnia ; Life-history ; Genetics ; Variation ; Maturation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Life-history traits of 101 clones from two populations of Daphnia magna were measured under controlled environmental conditions in the laboratory. Some individuals had four juvenile instars, others had five. This depended on their length at birth and on the population they came from. Females in the group with five juvenile instars were smaller at birth but larger and older at maturity than those with four juvenile instars. Within groups of females with equal numbers of preadult instars (instar groups) age and size at maturity increased with size at birth. This relationship differed significantly among instar groups for both age and size at maturity. Significant differences in age and size at maturity between two populations became non-significant when size at birth was used as a covariable in AN-COVA. Within populations, size at birth depended on the clone and on the parity of the clutch. First-clutch offspring were considerably smaller than those from later clutches. The results suggest that variability in life-history traits is common within and between clones, but that most of this variation can be accounted for by size at birth and the number of pre-adult instars.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00317537
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  • 2
    Electronic Resource
    Electronic Resource
    Changes of 6-benzylaminopurine and 2,4-dichlorophenoxyacetic acid concentrations in plant tissue culture media in the presence of activated charcoal (1993)
    Springer
    Plant cell, tissue and organ culture 33 (1993), S. 157-162 
    Details
    ISSN: 1573-5044
    Keywords: activated charcoal ; BAP adsorption ; 2,4-D adsorption ; coconut palm ; tissue culture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The rate of adsorption of 6-benzylaminopurine (BAP) and 2,4-dichlorophenoxyacetic acid (2,4-D) by activated charcoal (AC) from liquid and semi-solid tissue culture media was determined using 8-[14C]-BAP and 2-[14C]-2′,4′-D. For both liquid and semi-solid media an essentially constant ratio of free BAP: AC-bound BAP was reached between 5 and 10 days after preparation of the media. Pronounced increases in the level of available 2,4-D in the medium occurred, when either the initial BAP or 2,4-D level or both were raised to 5 × 10−4 M. When 2,4-D was used at 5 × 10−4 M the medium component sucrose (40 g l−1) caused a pronounced increase in available 2,4-D. Conversely the inclusion of the combined macro- and micronutrients markedly reduced the availability of free 2,4-D in the medium.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01983229
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  • 3
    Electronic Resource
    Electronic Resource
    Differences in life-history and aging in two clonal groups of Daphnia cucullata Sars (Crustacea: Cladocera) (1991)
    Springer
    Hydrobiologia 225 (1991), S. 245-253 
    Details
    ISSN: 1573-5117
    Keywords: Daphnia ; life history ; genotypes ; PGI ; aging ; clones
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Life-history traits were compared in twenty-two clones of Daphnia cucullata from the pre-alpine lake Klostersee in southern Germany. Clones were kept under standardized conditions (18 °C; 16:8 L/D) both singly and with 25 females per glass. Clones belonged to two genotype groups distinguished by enzyme electrophoresis. 11 of the clones had the genotype ‘FM’ at the phosphate glucose isomerase locus and 11 the genotype ‘MM’. Neonates and adults of the age class 10 to 21 days were larger in one group (FM) than in the other group (MM). The size specific growth rates within any age class depended on age and body size and differed between the genotype groups. The fecundity of young FM animals (〈 16 days) was significantly higher than that of MM animals, but for older females fecundity did not differ significantly. Senescence started about 6 days earlier in FM than in MM. The data are consistent with results of a field study on Daphnia cucullata in the Klostersee (Jacobs, 1990).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00028402
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  • 4
    Electronic Resource
    Electronic Resource
    Assessment of the changes of 2,4-dichlorophenoxyacetic acid concentrations in plant tissue culture media in the presence of activated charcoal (1990)
    Springer
    Plant cell, tissue and organ culture 20 (1990), S. 165-172 
    Details
    ISSN: 1573-5044
    Keywords: activated charcoal ; 2,4-D adsorption ; coconut palm ; tissue culture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The rate of adsorption of 2,4-dichlorophenoxyacetic acid (2,4-D) by activated charcoal (AC) from liquid and semi-solid tissue culture media was determined using 2-[14C]-2′,4′-D. In liquid medium 99.5% of the added 2,4-D (10-4 M) was adsorbed by AC (2.5 gl-1) within 5 days of preparation of the medium. Higher 2,4-D levels of reduced AC concentrations increased the level of available 2,4-D in the medium and extended the period necessary for the level of 2,4-D in the medium to become stabilized. In semi-solid medium the rate of adsorption of 2,4-D by AC was considerably reduced. A stable ratio of gel/2,4-D:AC/2,4-D was only reached after 10 to 20 days, depending on the 2,4-D concentration used. Low pH levels and maintenance of the medium at higher temperatures (20–30°C) accelerated the adsorption of 2,4-D by AC. In vitro tissue cultures of coconut palm showed marked differences in their growth response according to the age of the medium used and the associated variations in 2,4-D concentrations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00041877
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  • 5
    Electronic Resource
    Electronic Resource
    Modellrechnungen zu Explosionen freier Gaswolken von Kohlenwasserstoff/Luft-GemischenVortrag von F. Ebert auf der GVC-Tagung „Sicherheit in der Chemischen Technik“, 25./26. Febr. 1982 in Düsseldorf. (1982)
    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 54 (1982), S. 736-741 
    Details
    ISSN: 0009-286X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Model calculations on the explosion of free gas clouds containing mixtures of hydrocarbons and air. The procedure presented permits a description of continuously and discontinuously accelerated explosions. The explosions considered are deflagrations, i. e. combustion-supported compression waves. It is possible to calculate, for a given rate of propagation of a flame front or the motion of a piston assigned in a model, the corresponding flow field (compression wave). The corresponding pressure, density, and velocity distributions can be utilized for safety considerations. Application of the results requires that the simulated acceleration processes can be transformed into real events. With the experimental results presently available this is possible only in very crude fashion and can serve only as a rough preliminary guide.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cite.330540808
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  • 6
    Electronic Resource
    Electronic Resource
    Zur Bewegung feiner Partikeln, die in turbulent strömenden Medien suspendiert sind (1983)
    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 55 (1983), S. 931-939 
    Details
    ISSN: 0009-286X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Motion of fine grained particles, suspended in turbulent flow. This article considers the motion of particles, suspended in turbulent flow. If the particles are sufficiently small to respond to turbulence, their motion includes stochastic components. Concerning processes like air classification or separation of fine powders the stochastic contribution - characterized by the conception of a particle diffusivity - the particle motion exhibits a detrimental influence. Sharpness of cut and separation efficiency are reduced. The paper aims to present the state of the art in particle diffusion. First, theoretical investigations are reported, attention being focused on the equation of motion of the particle which is the link between the motion of the fluid and the motion of the particle. Then, experimental results are reviewed. The following tendencies can be seen: Particles which response to turbulence of fluid flow show increasing diffusivity with increasing inertia. Field forces like gravity or electrical field forces exhibit a damping effect on diffusivity.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cite.330551206
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  • 7
    Electronic Resource
    Electronic Resource
    Polyesters containing both rod-like and disc-like mesogens (1992)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 193 (1992), S. 507-513 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The synthesis of a new type of combined polymers containing both disc- and rod-like mesogens is reported. The polyesters, having a triphenylene derivative as a discotic mesogen in the side group and azobenzene or biphenyl derivatives as rod-like mesogens in the main chain were characterized by polarizing microscopy, differential scanning calorimetry, and X-ray scattering studies. The homopolymer 7 is highly crystalline, while the copolymer 8 is amorphous, both, however, do not form liquid-crystalline phases.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1992.021930222
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  • 8
    Electronic Resource
    Electronic Resource
    Polymer-solvent interactions: Dextrans in water and DMSO (1980)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 181 (1980), S. 1071-1080 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Enthalpies of solution, dilution and mixing of several dextran fractions with different molecular weights (MW) and low MW carbohydrates were determined in water and dimethyl sulfoxide at 25°C. The enthalpies of solution of dextran increase in the oligomer range up to a MW of about 1000; for higher MWs the enthalpies of solution are almost constant. The enthalpies of dilution decrease strongly with increasing MW and remain constant for MWs higher than 2 000. The interaction parameter was found to depend on the concentration of the solute in both solvents. From the experimental results it can be concluded that dimethyl sulfoxide is a better solvent for glucose and dextran than water. In dilute solutions glucose interacts considerably more strongly with the solvent than dextran. The conformational properties of dextran are similar in both solvents; for MWs above 2 000 the degree of solvation is found to be independent from the MW.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1980.021810511
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  • 9
    Electronic Resource
    Electronic Resource
    On the kinetics and mechanism of thermal degradation of polystyrene, 2.Part 1: cf.1. Formation of volatile compounds (1984)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 185 (1984), S. 991-1001 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Thermal degradation of polystyrene (PS) was carried out in the absence of oxygen between 292 and 336°C. The formed volatile products were analysed qualitatively and quantitatively by means of gas charomatography. It was found that the composition of the volatile fraction is a function of conversion and independent of temperature for most of the products. A radical chain mechanism is proposed to explain these experimental results.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1984.021850513
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  • 10
    Electronic Resource
    Electronic Resource
    Elastic and quasielastic light scattering studies on the branching characteristics of dextrans (1984)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 185 (1984), S. 2205-2212 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The influence of branching on the radius of gyration and the hydrodynamic radius of dextran macromolecules was studied by elastic and quasielastic light scattering (ELS and QELS). The hydrodynamic radius is more sensitive to low levels of branching than the radius of gyration. At higher branching levels a saturation of the hydrodynamic radius rh is observed, while the radius of gyration rG still changes distinctly. The ratio rG/rh proves to be a measure of the flexibility of the macromolecules; the latter is increasing with molecular weight for short linear chains and is decreasing with increasing degree of branching. Measurements were carried out in water (thermodynamically good solvent) and in ethylene glycol (under theta conditions) on four series of dextran fractions having rather narrow molecular weight distributions.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1984.021851015
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