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  • 1
    Electronic Resource
    Electronic Resource
    Analytical and numerical analysis of Debye–Ramm's equation for the polarization density distribution in polar materials (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 5399-5410 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Due to dipole interaction, the molecular polarization brought about by an external field is significantly lower in condensed matter (liquids) than in a gas. In addition to this, the response of interacting dipoles to stepwise changes of the external field does not follow a simple time exponential. Instead, a spectrum of relaxation times is required to describe such a response. Debye and Ramm [Ann. Phys. 28, 28 (1937)] have attempted to describe the effects associated with rotational hindrances due to dipole-dipole interaction by the following differential equation: ∂f/∂t =(kT/ρ)Δf+(1/ρ)div(f grad u), where f denotes the distribution function specifying the number of dipoles pointing in a certain solid angle, t the time, ρ a friction coefficient, and u the potential of the forces acting on the dipoles. The latter quantity depends both on the external field and on the contribution from the dipole-dipole interaction (internal field). Although unable to solve the above equation explicitly, Debye and Ramm (DR) made some predictions about the solution, concluding, among other things, that the inclusion of an internal field E would yield a process with a discrete spectrum of relaxation times. Finding such prospect highly interesting, we subjected the DR equation to a close study using some advanced mathematical tools (Fourier integral operators etc.). Contrary to the conclusions of DR, we found that the above equation cannot be solved in the way originally described, and that the conjectured eigenfunctions and eigenvalues do not exist. Furthermore, we show that, in contrast to DR's statements, the above equation is not solved by certain classical expressions relating to free-rotating dipoles (no internal field). The lack of physical content of this equation appears to be due to a number of not permissible simplifications.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.357195
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  • 2
    Electronic Resource
    Electronic Resource
    Methods to increase the efficiency of a metallic monolithic catalyst (1993)
    s.l. : American Chemical Society
    Industrial & engineering chemistry research 32 (1993), S. 1081-1086 
    Details
    ISSN: 1520-5045
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ie00018a014
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  • 3
    Electronic Resource
    Electronic Resource
    Formation of nitrous oxide in circulating fluidized-bed boilers (1991)
    s.l. : American Chemical Society
    Energy & fuels 5 (1991), S. 815-823 
    Details
    ISSN: 1520-5029
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ef00030a008
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  • 4
    Electronic Resource
    Electronic Resource
    A Metastable Selenium-Related Center in Silicon (1993)
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 143-147 (Oct. 1993), p. 159-164 
    Details
    ISSN: 1662-9752
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/02/00/transtech_doi~10.4028%252Fwww.scientific.net%252FMSF.143-147.159.pdf
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  • 5
    Electronic Resource
    Electronic Resource
    Effects of lumbricids and enchytraeids on nematodes in limed and unlimed coniferous mor humus (1994)
    Springer
    Biology and fertility of soils 17 (1994), S. 201-205 
    Details
    ISSN: 1432-0789
    Keywords: Bacteria ; Bacterial-feeding nematodes ; Cognettia sphagnetorum ; Dendrobaena octaedra ; Enchytraeidae ; Humus ; Lime ; Lumbricidae ; Nematoda ; Protozoa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In a factorial laboratory experiment, specimens of Dendrobaena octaedra (Lumbricidae) and Cognettia sphagnetorum (Enchytraeidae) were added to microcosms with unlimed (pH 4.5) and limed (pH 5.5) coniferous mor humus containing bacteria, fungi, protozoans, and nematodes. Effects on the nematodes were assessed after an incubation period of 207 days at 15°C and a soil moisture content of 60% water-holding capacity. When D. octaedra was absent, nematodes were significantly more abundant in the limed humus than in the unlimed humus. The presence of D. octaedra markedly reduced the number of nematodes in the limed humus but not in the unlimed one, where D. octaedra lost weight and probably did not feed. Most nematodes (92–97%) were bacterial-feeders. The presence of D. octaedra did not decrease the number or biomass of bacteria, indicating that the reduction in nematode numbers was not the result of competition for bacteria between D. octaedra and the nematodes. The presence of C. sphagnetorum had no effect on the nematodes in either of the treatments. We suggest that the reason why D. octaedra, but not C. sphagnetorum, reduced nematode numbers is that the former was more likely to inadvertently ingest the nematodes because of its much greater size. The results provide a possible explanation for the observation that liming sometimes enhances nematode populations, when lumbricids do not respond to the treatment, and sometimes causes decreases, when lumbricids increase in number.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00336323
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  • 6
    Electronic Resource
    Electronic Resource
    Impairment of estramustine phosphate absorption by concurrent intake of milk and food (1990)
    Springer
    European journal of clinical pharmacology 38 (1990), S. 189-193 
    Details
    ISSN: 1432-1041
    Keywords: estramustine phosphate ; prostatic cancer ; gastrointestinal absorption ; food intake ; calcium ; drug interaction ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The effect of milk and food on the pharmacokinetics of estramustine phosphate was investigated in six patients with prostatic cancer. In a randomized three-way cross-over study, the patients were given single doses of the drug together with low calcium water, low calcium food and milk. The evaluation was based upon the plasma concentration of two metabolites, estromustine and estrone, as parent drug could not be detected in plasma. The tmax and lag time of estromustine were significantly increased by milk and food intake and Cmax and AUC were significantly decreased. In comparison with water, the AUC of estromustine was 41% when the drug was taken with milk and 67% after simultaneous intake of standardized food. Corresponding figures for the peak values were 32 and 57%, respectively. The effect of milk and food intake on the pharmacokinetics of estrone was similar. Studies in vitro demonstrated that the dissolution of estramustine phosphate disodium was markedly impaired in the presence of calcium. It was concluded that the rate and extent of absorption of estramustine phosphate were decreased when the drug was taken with milk or food due to the formation of a poorly absorbable calcium complex. To obtain high and reproducible absorption of Estracyt®, the drug should not be taken together with milk, milk products or other calcium-rich food or drugs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00265983
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  • 7
    Electronic Resource
    Electronic Resource
    Effects of salinity and bromine on zygotes and embryos of Fucus vesiculosus from the Baltic Sea (1992)
    Springer
    Marine biology 114 (1992), S. 661-665 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Zygotes and young embryos derived from Fucus vesiculosus collected in the archipelgo of Stockholm in 1990, growing at a salinity of 6 to 7‰ S, were cultured under different salinity conditions and in media of different bromine concentrations. Optimum salinity was 10 to 12‰ S for germination (rhizoid initiation) while apical hair formation showed a broader tolerance curve with an optimum at 8 to 14‰ S. Bromine caused inhibition of early development of F. vesiculosus. At 6‰ salinity a 50% reduction in germination took place at 10.0 mM Br and at 1.25 mM Br only 4.7% of the embryos developed apical hairs, as compared to 32.7% in the control. Bromine toxicity decreased at higher salinities. The results indicate that F. vesiculosus in the Baltic Sea has diverged from its Atlantic progenitors and to some extent acclimated to low salinity. Still, the salinity in the normal environment of the tested population is lower than optimum, leading to a lower degree of germination of zygotes, a lower growth rate of young embryos and probably also a higher sensitivity to additional stress factors such as chemical pollution.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00357263
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  • 8
    Electronic Resource
    Electronic Resource
    Thermal conductivity and heat capacity per unit volume of poly(methyl methacrylate) under high pressure (1994)
    Springer
    International journal of thermophysics 15 (1994), S. 949-962 
    Details
    ISSN: 1572-9567
    Keywords: bulk modulus ; heat capacity ; high-pressure poly(methyl methacrylate) ; thermal conductivity ; transient hot-wire method
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The thermal conductivity and heat capacity per unit volume of poly(methyl methacrylate) (25 and 350 kg · mol− in molecular weight) have been measured in the temperature range 155–358 K at pressures up to 2 GPa using the transient hot-wire method. The bulk modulus has been measured up to 1.0 GPa at 294 K and yielded a constant valueg = 3.4 ± 0.3 for the Bridgman parameter. No dependence on molecular weight could be detected in the properties we measured.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01447105
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  • 9
    Electronic Resource
    Electronic Resource
    Chiral amino acid microanalysis by direct optical resolution of fluorescent derivatives on BSA-based (resolvosil) columns (1991)
    Springer
    Chromatographia 31 (1991), S. 429-433 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Chiral separations ; Amino acids ; Fluorogenic derivatization ; N-(Chloroformyl)-carbazole
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A new reagent for fluorescence labelling of amino acids, N-(chloroformyl)-carbazole, has been used in order to achieve high sensitivity of detection as well as good optical resolution. The derivatization reaction is fast and conveniently carried out at room temperature by shaking a buffered aqueous solution of the amino acids with an acetone solution of the reagent. The individual derivatized amino acids are first separated and collected via chromatography on a standard octadecyl-silica column. Each amino acid derivative is then analyzed for enantiomer composition by re-injection on a BSA-silica (Resolvosil®) column using fluorescence detection. For some amino acids (alanine, threonine, phenylalanine, tryptophan) enantiomeric separation factors exceeding α=3 have been obtained. The phosphonic acid analogue of alanine (1-aminoethylphosphonic acid) was also found to be well resolved into its enantiomers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02262384
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  • 10
    Electronic Resource
    Electronic Resource
    Reducing NOx in diesel exhausts by SCR technique: Experiments and simulations (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1911-1919 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Results of experiments are compared to simulations of the performance of V2O5/γ-alumina SCR catalyst used to remove nitrogen oxides from diesel exhausts. The kinetic model is based on Eley-Rideal kinetics. Temperature programmed desorption (TPD) of the ammonia is used to evaluate adsorption/desorption parameters. Stationary experiments on a 3.6-dm3 engine with a 4.8-dm3 honeycomb catalyst is used to evaluate kinetic rate parameters for the reduction of NO with NH3. The desorption activation energy, Ea,des, is best fitted as a function of surface coverage yielding Ea,des = 240* (I -0.44* θNH30.36) kJ/mol. A dynamic test (FTP) with a 12-dm3 engine and24.8-dm3 honeycomb catalyst is done with astoichiometric injection of ammonia. The NOx conversion is 52%, but during the freeway traffic the conversion reached 72%. The prediction of NOx conversion is good, but there are some deviations for temperature and ammonia slip.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690401115
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