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  • 1
    ISSN: 1573-4927
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Hydrobiologia 140 (1986), S. 125-133 
    ISSN: 1573-5117
    Keywords: Nepal ; Lake Rara ; water chemistry ; primary productivity ; zooplankton ; oligotrophy ; landslide area
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A survey of oligotrophic Lake Rara, the biggest lake in Nepal, was carried out from 1982 till 1984. Mean depth is 100 m, and maximum depth is 167 m. The surface area covers 9.8 km2, and the lake contains 0.98 km3 volume of water. Transparency was about 16 m, photoquantum yield decreased exponentially with depth below 5 m, and the extinction coefficient was 8.3 × 10−2. The concentration of Chl.-a was in the range of 0.06–0.46 mg m−3, and total nitrogen was 18–30 μg 1−1. The whole water column was well oxygenated. Primary productivity was extremely low. It has more than 30 inflowing brooks and one outlet. The water quality of the brooks changes drastically with their location. The pH, electrical conductivity, and EDTA hardness in the waters from a landslide area were high. In the waters from a rich pine forest they were extremely low. The zooplankton consisted of two species of protozoa, five species of rotifers, two species of Cladocera, and two species of Copepoda. The zooplankton density range was 6200–16200 individuals m−3. The minimum was on November 11th, 1983 and the maximum on August 19th, 1983.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Hydrobiologia 71 (1980), S. 233-237 
    ISSN: 1573-5117
    Keywords: urea ; urea-decomposing bacteria ; distribution ; activities
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The present study deals with the distribution of free and attached urea-decomposing bacteria in waters of Lake Suwa, one of the typical eutrophic lakes in Japan. Urea-decomposing bacteria are proved to be not an exceptional population among the populations of the heterotrophic bacteria studied. The percentage of attached urea-decomposing bacteria versus attached heterotrophic bacteria seems to be higher than that of free urea-decomposing bacteria versus free heterotrophic bacteria. Based on the assumption that most bacterial ureases are inducible ones, it is inferred that their ureases may not be induced under a such degree of urea concentration as is generally encountered in natural waters.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Hydrobiologia 83 (1981), S. 153-160 
    ISSN: 1573-5117
    Keywords: urea-decomposition ; free bacteria ; phytoplankton ; annual change
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Free bacterial populations were separated from an intact planktonic community in water of a eutrophic reservoir in Japan by filtration through Whatman GF/ C glass fiber filters (mean porosity 1.2 µm). Urea decomposition by the free bacterial populations and the intact planktonic community was determined in six different months. The separated free bacteria apparently did not take part in urea-decomposition in waters of the reservoir through the year: the number of free heterotrophic bacteria increased during the urea-decomposition experiments, however, the concentration of urea did not decrease. Whereas, in five cases out of six, urea was decomposed by the intact planktonic community. Probably, phytoplankton were responsible for most of the urea-decomposition. On the assumption that the decomposition of urea obeyed first-order kinetics, rate constants were calculated to be 0.00–0.63 day−1 with a mean value of 0.21 day−1.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Journal of Raman Spectroscopy 20 (1989), S. 233-237 
    ISSN: 0377-0486
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Raman spectra of p-cresol, a model compound for tyrosine, were measured in solutions of various solvents, paying special attention to the effects of hydrogen bonding on the Raman bands in the 1300-1150 cm-1 region. The frequency of the ν7a (C—O stretch) band was found to be sensitive to the state of hydrogen bonding at the phenolic hydroxyl group. It occurs at 1275-1265 cm-1 in proton-donating states, 1240-1230 cm-1 in proton-accepting states and around 1255 cm-1 in weakly or non-hydrogen-bonding states. This relationship between the ν7a′ frequency and hydrogen bonding was verified in the Raman spectra of L-tyrosine and its derivatives in the crystalline state. Analysis of the crystal Raman spectra further suggested that the ν7a (C—C stretch) frequency also serves as a marker, though less sensitive, of hydrogen bonding and the ν9a (C—H bend) frequency reflects the displacement of the OH hydrogen atom from the plane of benzene ring, which may be induced by hydrogen bonding. These Raman bands are strong with UV excitation and are expected to be useful in characterizing tyrosine side-chains in peptides and proteins by UV resonance Raman spectroscopy.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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