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  • 1
    Electronic Resource
    Electronic Resource
    Zero-field-splitting and π-electron spin densities in the lowest excited triplet state of oligothiophenes (1996)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 105 (1996), S. 4441-4447 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The electronic properties of thiophene oligomers (nT, n=2–8) have been investigated in the lowest excited triplet state. Theoretical calculations of the zero field splitting parameters and of the π-electron spin density have been performed and compared with previous experimental EPR results. The calculations are based on a simple π-electron (one-electron-per-site) model including electron–electron interaction at the extended Hubbard level. Optimized bond lengths result from making them self-consistent to the corresponding bond orders via Coulson's relationship. The calculated D values decrease from D=0.0959 cm−1 for n=2 to D=0.0597 cm−1 for n=8, in agreement with EPR data. The measured as well as the calculated E values are rather small. Furthermore, we found that ZFS parameters are affected by the torsion angles between the thiophene rings. The chain length dependence of D can be rationalized comparing π-electron spin density calculations and computed bond length distortions. These clearly indicate that the triplet excitation reaches a finite extension over about four thiophene rings. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.472296
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  • 2
    Electronic Resource
    Electronic Resource
    Band structures of neutral and doped (C"6"0)"x polymers
    Amsterdam : Elsevier
    Solid State Communications 92 (1994), S. 407-411 
    Details
    ISSN: 0038-1098
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0038-1098(94)90518-5
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  • 3
    Electronic Resource
    Electronic Resource
    Organic nitrogen compounds extracted from arable and forest soils by electro-ultrafiltration and recovery rates of amino acids (1988)
    Springer
    Biology and fertility of soils 5 (1988), S. 271-275 
    Details
    ISSN: 1432-0789
    Keywords: Electro-ultrafiltration ; Soil N ; Aminoacid N ; Hydrolysable N ; Extractable organic N
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Extraction of synthetic amino acids dissolved in water by means of electro-ultrafiltration (EUF) showed average recovery rates of about 75%. Higher losses were obtained, particularly with cysteine, methionine and NH4 4; the latter, probably being deprotonated at the cathode, may be lost in form of NH3. The EUF extracts of three arable and two forest soils were investigated for their N compounds. In the arable soils only about 3% of the total organic N extracted by EUF was free amino acids; about 23%–55% consisted of amino N (hydrolysable N) and the rest was non-hydrolysable N. The two forest soils contained higher amounts of EUF-extractable organic N compared with the arable soils. In the two forest soils the content of free amino-acid N amounted to 8% and 11% of the EUF organic N, and the proportion of hydrolysable N from total EUF-organic N was 41% and 46%. It is suggested that the amino-acid N and the hydrolysable N can be easily mineralized.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00262130
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  • 4
    Electronic Resource
    Electronic Resource
    Relationship between electroultrafiltration (EUF) extractable nitrogen, grain yield, and optimum nitrogen fertilizer rates for winter wheat (1992)
    Springer
    Nutrient cycling in agroecosystems 32 (1992), S. 37-43 
    Details
    ISSN: 1573-0867
    Keywords: nitrogen fertilizer rate ; electroultrafiltration ; wheat ; soil test
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The objective of the investigation was to examine whether there exist relationships between the optimum nitrogen fertilizer rate for winter wheat and soil nitrogen fractions extracted by electroultrafiltration (EUF) from autumn samples of the upper soil layer (0–30 cm). Optimum nitrogen fertilizer rates were derived from grain yield curves of field trials carried out with increasing nitrogen fertilizer rates on 19 different sites in 1985/86 and 1986/87. Most soils were luvisols derived from loess, two soils were brown earths and one a pararendzina. Total Nitrogen fertilizer rates were 0, 40, 80, and 120 kg N/ha applied twice before ear emergence. The final nitrogen rate at ear emergence was the same for all treatments, namely 60 kg N/ha. Optimum nitrogen fertilizer rates were derived from the grain yield curve fitted to a modified Mitscherlich equation. The optimum nitrogen fertilizer rates were correlated with the nitrogen fractions extracted by EUF. The regression equation thus obtained showed that NO 3 - , the organic N fraction (EUF Norg), and the EUF Norg-quotient each had a highly significant impact on the optimum nitrogen fertilizer rate. The higher the amounts of EUF-N extracted the lower the optimum nitrogen rate. Substituting the EUF Norg-fraction for total nitrogen concentration in the upper soil layer gave a poorer relationship between the optimum nitrogen fertilizer rate and the soil data. In absolute terms the EUF Norg-fraction had by far the greatest impact on calculating the optimum nitrogen fertilizer rate. The investigation shows that the EUF method is a suitable technique for the determination of available soil nitrogen from which optimum nitrogen fertilizer rates can be derived for winter wheat cultivated under soil and climatic conditions typical for cereal growing areas in central Europe.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01054392
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  • 5
    Electronic Resource
    Electronic Resource
    Measurement and drug induced modulation of interleukin-1 level during zymosan peritonitis in mice (1995)
    Springer
    Inflammation research 44 (1995), S. 248-252 
    Details
    ISSN: 1420-908X
    Keywords: Interleukin-1 ; Zymosan peritonitis ; Anti-inflammatory drugs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The time-course and pharmacological modulation of interleukin-1 (IL-1) production were investigated during zymosan induced peritonitis in mice. IL-1α liberation was assessed by specific immunoassay (ELISA) and the IL-1 like bioactivity (sensitive to bothα- andβ-forms of IL-1) was measured by a sensitive bioassay (D10G4.1 costimulation). I.p. injection of zymosan induced significant IL-1 release into the peritoneal exudate. The level peaked at 4h and by 24h dropped below the detection limit in both assays. The effects of the prototypical antiinflammatory drugs indomethacin (IND) and dexamethasone (DEX) and that of IX 207-887, a compound which has been reported to interfere primarily with IL-1 production, were also tested. DEX and IX 207-887 dose-dependently decreased the immunoassayable IL-1α level and the IL-1 like bioactivity as well. However, IND had no suppressant effect. Thus, the data obtained by immunoassay and bioassay correlated well proving the suitability of zymosan peritonitis model for the examination of IL-1 production in experimental inflammation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01782977
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  • 6
    Electronic Resource
    Electronic Resource
    Influence of guar on serum lipids in patients with hyperlipidaemia (1989)
    Springer
    European journal of clinical pharmacology 37 (1989), S. 117-120 
    Details
    ISSN: 1432-1041
    Keywords: cholesterol ; guar ; hyperlipidaemia ; HDL-/LDL-cholesterol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The antihyperlipidaemic effect of a guar preparation which absorbs a particularly large amount of water has been examined in 13 patients with Type II hyperlipidaemia. A 30-day pre-treatment phase was followed by 60 days of treatment with 4 g guar dissolved in 200-ml liquid at each meal-time (total guar 12 g/day), and a 60-day post-treatment observation period. Routine other clinical blood tests were performed 30, 15 or 0 days before treatment, 15, 30 and 60 days after the start of treatment, and 30 and 60 days after its end. Total cholesterol fell by 0.85 mmol·l−1, from a pre-treatment concentration of 7.4 mmol·l−1 to a treatment value of 6.5 mmol·l−1, and LDL-cholesterol fell by 0.64 mmol·l−1, from 5.5 mmol·l−1 to a treatment value of 4.8 mmol·l−1. There was no significant change in triglyceride and VLDL concentrations during the study. A slight but significant fall in HDL-cholesterol was seen. The sole adverse effect was occasional intestinal discomfort.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00558217
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  • 7
    Electronic Resource
    Electronic Resource
    Determination of categories of soil nitrogen by electro-ultrafiltration (EUF) (1979)
    Springer
    Plant and soil 53 (1979), S. 445-453 
    Details
    ISSN: 1573-5036
    Keywords: Alluvial soils ; Ammonium ; Amino acids ; Chernozem ; Clay minerals ; Electroultrafiltration ; EUF Nitrate ; Nmin ; N release ; N reserves
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The determination of N fractions in the soil by means of electro-ultrafiltration (EUF) is described. The results can be summarized as follows: 1) For aqueous soils suspension the direction of NH4 + and NO3 − migration in an electric field is determined by electrical charge and water flow. Therefore the filtrates obtained at both the cathode and anode can be mixed for subsequent analysis for NH4−N and NO3−N. In order to avoid N losses the volatile NH3 is recovered in 1N HCl solution. 2) Considerable amounts of NH4−N and NO3−N as well as low-molecular organic N compounds can be determined by EUF in soil samples taken from June to September. The readily available N is extracted by EUF at 20°C and 200 V, while determinations at 80°C and 400 V also give information on N release from reserves. 3) It was demonstrated with soils from long term N and K fertilizer experiments that the EUF−NO3 contents reflect the N accumulation in the soil due to N fertilization or plant residues. In clayrich soils the EUF−NH4 contents give information on the release of fixed NH4. Moreover EUF−NH4 also gives information on N from readily mineralizable organic compounds. The EUF procedure gives improved insight into the N dynamics of a site and this should serve as a basis for N-fertilizer recommendations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02140716
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  • 8
    Electronic Resource
    Electronic Resource
    The effect of K fertilization and K removal by ryegrass in pot experiments on the K concentration of the soil solution of various soils (1975)
    Springer
    Plant and soil 42 (1975), S. 97-107 
    Details
    ISSN: 1573-5036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The effect of K fertilization and K removal by perennial ryegrass grown in potson the K concentration of the soil solution of very different soils is described. The following results have been obtained: 1) With similar content of exchangeable K the K concentration of the soil solution varies widely according to soil properties. 2) Equal amounts of fertilizer K increase the K concentration of the soil solution to a different extent depending on soil properties. 3) The level of the K concentration of the soil solution alone does not indicate how rapidly it can be raised by K supply. A diagram based on the evaluation of both parameters (i.e. exchangeable K and K concentration of the soil solution), however, will give a good picture of the K dynamics of a soil. 4) The K desorption curves obtained by EUF and the K concentration of the soil solution show similar changes after K fertilization. 5) The highest yields were obtained with the highest K concentration in the soil solution. 6) The depressions in yield observed in the course of the four cuts differed among the various soils and were in line with the decrease in the K concentration of the soil solution. 7) With similar contents of exchangeable K, equal removals of K affected the K concentration of the soil solution to a different extent. The exchangeable K alone, therefore, cannot be considered as a reliable parameter of the buffer capacity of the K concentration in the soil solution. 8) The course of the K desorption curves gives good information on the rate of decrease in the K concentration of the soil solution due to plant removal. Thus the yield curves are in good agreement with the course of the corresponding EUF curves.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02186976
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  • 9
    Electronic Resource
    Electronic Resource
    EUF-K as measure of K availability index for Tamil Nadu soils (India) (1982)
    Springer
    Plant and soil 64 (1982), S. 95-104 
    Details
    ISSN: 1573-5036
    Keywords: K potential ; K reserve ; EUF-K ; K uptake by rice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Representative soils of Tamil Nadu could be grouped into three categories based on the cumulative EUF desorption K curves which were exponential and displayed marked differences in the magnitude of K release by the soils employed. The cumulative K desorption values and the cumulative K uptake values of rice were found to be closely correlated. When compared with any other method, the cumulative EUF desorption K was found to be a better measure of K availability index.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02375164
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  • 10
    Electronic Resource
    Electronic Resource
    Electro-ultrafiltration of aqueous soil suspension with simultaneously varying temperature and voltage (1982)
    Springer
    Plant and soil 64 (1982), S. 7-23 
    Details
    ISSN: 1573-5036
    Keywords: Fertilizer requirement ; Nutrient availability ; Nutrient fractions ; Nutrient reserves ; Soil analysis ; Soil solution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The procedure of electro-ultrafiltration (EUF) with simultaneously varying voltage and temperature for the determination of nutrient fractions in soil as well as for the characterization of important soil properties such as kind of clay, content of K-selective clay minerals, of CaCO3 etc. is described. The interpretation of the EUF-N, EUF-P and EUF-K fractions is discussed in detail with regard to their availabilities. Moreover the influence of soil properties and soil management on the EUF nutrient fractions is discussed. For characterization of the EUF values needed for optimum plant nutrition, it is suggested to combine the EUF values at 20°C and 200 V on the one hand (easily available fraction) and the EUF values at 80°C and 400 V on the other (nutrient reserves). The higher, in fact, the nutrient contents at 80°C and 400 V are the lower can be the EUF values at 20°C and 200 V. In contrast to conventional methods of soil analysis, the nutrient contents determined by EUF are expressed in mg/100 g soil/time unit of desorption (min) at given temperature and voltage. The EUF procedure proved highly advantageous for an assessment of the fertilizer requirements of soils as this method allows for the determination of soil properties such as kind of clay, content of K-selective clay minerals, of CaCO3 and of easily desorbable heavy metals in one single operation. These soil properties play a decisive role in the sorption of K and P.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02375153
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