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  • 1
    Electronic Resource
    Electronic Resource
    Do tides affect water quality in the upper phreatic zone of a small oceanic island, Sipadan Island, Malaysia? (1997)
    Springer
    Environmental geology 29 (1997), S. 112-117 
    Details
    ISSN: 1432-0495
    Keywords: Key words Water quality ; Tidal change ; Upper phreatic zone ; Oceanic island
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract  Sipadan Island is a small oceanic island with limited storage of fresh groundwater. A study was carried out to determine the effect of tidal change on the groundwater quality of such an island using temperature, dissolved oxygen content, conductivity, salinity, and pH values as indicators. Overall, the results indicated that the groundwater quality changes with tides, but the trends of fluctuation differs between the observed parameters. It was found that the percentages of changes during the period of study were 0.8% (temperature), 53% (dissolved oxygen), 61% (conductivity), 58% (salinity), and 1.7% (pH) at the centre of the island; and 0.9% (temperature), 33% (dissolved oxygen), 40% (conductivity), 42% (salinity), and 9% (pH) at a station 120 m from the coast, based on 2.9-m and 2.8-m tidal ranges at each station.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002540050109
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Microbial and enzyme activity in soils amended with a natural source of easily available carbon (1996)
    Springer
    Biology and fertility of soils 21 (1996), S. 177-183 
    Details
    ISSN: 1432-0789
    Keywords: Key words Heterotrophic microorganisms ; Nitrification ; P solubilization ; S oxidation ; Soil enzymes ; Sugar beet
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The addition of sugar beet to soils as a source of C led to an increase in the availability of easily utilizable C (glucose), which in turn markedly increased numbers of soil bacteria and of the yeast Williopsis californica. Nitrification, P solubilization, urea hydrolysis (and the subsequent nitrification of liberated NH) were stimulated by this amendment. The stimulation of nitrification may have been a result of increased heterotrophic nitrification. In contrast, the concentration of sulphate in S0-amended soils declined following amendment, presumably as the result of enhanced S immobilization. Activity of the enzymes amylase, aryl sulphatase, invertase, phosphatase, dehydrogenase, and urease were all stimulated by the sugar beet amendment. These results suggest that sugar beet amendment could be used to increase the rate of release of plant-available ions from fertilizers such as insoluble phosphates. Problems may arise, however, from a subsequent increase in nitrification and reduced sulphate availability.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00335931
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Microbial and enzyme activity in soils amended with a natural source of easily available carbon (1996)
    Springer
    Biology and fertility of soils 21 (1996), S. 177-183 
    Details
    ISSN: 1432-0789
    Keywords: Heterotrophic microorganisms ; Nitrification ; P solubilization ; S oxidation ; Soil enzymes ; Sugar beet
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The addition of sugar beet to soils as a source of C led to an increase in the availability of easily utilizable C (glucose), which in turn markedly increased numbers of soil bacteria and of the yeast Williopsis californica. Nitrification, P solubilization, urea hydrolysis (and the subsequent nitrification of liberated NH inf4 sup+ ) were stimulated by this amendment. The stimulation of nitrification may have been a result of increased heterotrophic nitrification. In contrast, the concentration of sulphate in So-amended soils declined following amendment, presumably as the result of enhanced S immobilization. Activity of the enzymes amylase, aryl sulphatase, invertase, phosphatase, dehydrogenase, and urease were all stimulated by the sugar beet amendment. These results suggest that sugar beet amendment could be used to increase the rate of release of plant-available ions from fertilizers such as insoluble phosphates. Problems may arise, however, from a subsequent increase in nitrification and reduced sulphate availability.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00335931
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Frequency dependence of the complex impedances and dielectric behaviour of some Mg–Zn ferrites (1997)
    Springer
    Journal of materials science 32 (1997), S. 5817-5823 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Complex impedances of some magnesium–zinc ferrites, MgxZn1-xFe2O4 (x=0.4, 0.5, 0.6 and 0.7), in the frequency range of 1 mHz–10 MHz were measured at 300 K. The complex-plane impedance spectrum from each sample indicates that the capacitive and the resistive properties of the materials are mainly attributed to the processes that associated with the bulk (grain) and the grain boundary. A low-frequency dispersion (LFD) and a negative capacitance regions are also observed at low frequencies. A small series resistance of about the same value for all samples is also observed. The bulk and the grain boundary components are analysed by assuming a two-layer leaky capacitor. The simulated complex impedances using the Cole–Cole expression are in agreement with the measured values. The dielectric properties of the materials are attributed to the interfacial polarization and LFD at low frequencies and the orientational polarization at high frequencies. These properties result in the dielectric loss which composed of a Debye-like loss peak at high frequency end and a strong LFD below 1 Hz. Both regions exhibit universality with regard to the power-law relation between the dielectric loss (ε″r or χ″) and frequency as given by ε″r∝ωn-1, where n=0.14 and n=0.02, respectively. The exponent is marginally negative, n=−0.03, in the region of negative capacitance below 3–4 mHz. The variations of the above properties and the characteristic parameters for different compositions of the Mg–Zn ferrites are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018690322459
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  • 5
    Electronic Resource
    Electronic Resource
    Comparative pharmacokinetic study of oral and rectal formulations of artesunic acid in healthy volunteers (1998)
    Springer
    European journal of clinical pharmacology 54 (1998), S. 411-414 
    Details
    ISSN: 1432-1041
    Keywords: Key words Artesunic acid ; Pharmacokinetics ; Malaria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract Objective: A single cross-over, comparative pharmacokinetic study of oral and rectal formulations of 200 mg artesunic acid in 12 healthy Malaysian volunteers is reported. Methods: Plasma concentrations of artesunic acid and dihydroartemisinin were determined simultaneously by HPLC with electrochemical detection. The test drug was well tolerated and no undesirable adverse effects were observed. Results: Comparison of pharmacokinetic parameters of artesunic acid after oral and rectal administration showed statistically significant differences in t max and AUC, with no changes for C max and t 1/2. As for dihydroartemisinin, differences were observed for t max and C max but not for AUC. Conclusion: There appear to be pharmacokinetic differences between oral and rectal modes of administration. The significance of these findings should be explored in malaria patients before appropriate therapeutic regimens are devised.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002280050484
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  • 6
    Electronic Resource
    Electronic Resource
    Chemical and Bacteriological Monitoring of Drinking Water from an Urbanised Water Catchment Drainage Basin (1997)
    Springer
    Environmental monitoring and assessment 44 (1997), S. 327-338 
    Details
    ISSN: 1573-2959
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The Linggi river drainage basin in Negeri Sembilan, Malaysia supplies water to the whole of Port Dickson district and meets 50% of the Seremban district needs. The Linggi River, the main tributary, passes through the highly urbanised and densely populated Seremban district while the water treatment plant is located 16 km downstream. In 1979 the USEPA declared the river unsuitable as a source of raw water whereas the WHO classified it as being heavily polluted requiring more extensive and effective treatment. In order to meet the WHO drinking water standards, an ozonation system was installed in the conventional water treatment plant. The objective of ozonation is for the control and removal of organic micropollutants and other deleterious matters. This study investigated the concentrations and distribution of organic micropollutants, heavy metals, and bacteriological counts in water samples collected from within the catchment and the treated water. The effectiveness of the ozonation system was also studied. The total level of phenolic water pollutants in the catchment was generally found to be very much higher than the maximum recommended level of 2.0 µgl-1. The extensive treatment process carried out at the plant was very effective in reducing the levels of total phenols in the treated water to less than 1.0 µgl-1. However the process was not efficient enough to reduce the levels of some heavy metals as required by the standards, for examples Cd and Pb were still three times higher than the standards of 5µgl-1 and 0.05 mgl-1 respectively. For bacteriological study, coliform group of bacteria, Salmonella, faecal streptococci and injured coliform were monitored in the raw and treated water. The raw water contained coliforms about 1000 times higher than the required standard for raw ater, but after the secondary treatment by ozonation coliform bacteria were absent, however a small number of Salmonella was still present occasionally. The study also showed that restructuring of the district and relocating of some commercial activities along the river banks to other areas carried out over the last five years has improved the general quality of the river water.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005795615266
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  • 7
    Electronic Resource
    Electronic Resource
    Determination of mercury and methylmercury in hair samples by neutron activation (1997)
    Springer
    Journal of radioanalytical and nuclear chemistry 216 (1997), S. 25-27 
    Details
    ISSN: 1588-2780
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Mercury and methylmercury in hair samples were determined by neutron activation analysis. Samples were digested in 10M NaOH, and methylmercury was then isolated by solvent extraction with toluene. The isolated methylmercury was then absorbed onto cysteine paper. The dried cysteine paper was activated for six hours in a TRIGA reactor and methylmercury was analysed via 279.2 keV of203Hg. Methylmercury and total mercury in some standard reference materials were also analysed, and the results were in good agreement with those reported in the literature. Results for hair samples showed that the methylmercury concentration ranged 14–40% of the total mercury. Gas chromatogram showed that methylmercury was only present in the samples analysed. In samples where methylmercury and other organic mercury are presented, the NAA method is good for the determination of the total organic mercury only.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02034489
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  • 8
    Electronic Resource
    Electronic Resource
    Substitution of yttrium by strontium in YBa2Cu3O7−δ superconductors (1996)
    Springer
    Journal of materials science 15 (1996), S. 205-207 
    Details
    ISSN: 1573-4811
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00274452
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