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  • 1
    ISSN: 1432-0975
    Keywords: Key words Coral Reef ; Manta tow ; Survey ; Benthic video ; Observer ; Comparisons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract  There is limited information on the validity and reproducibility of estimates of benthic cover from manta tow surveys. To address this, benthic cover estimates from the same reef area were compared (i) among observers and (ii) with an independent assessment using under-water video. Benthic cover was classified into 11 categories. There was generally unbiased agreement within one cover category, both among observers (89%) and for comparisons between manta tow and video (86%). While estimates of dead coral cover were reproducible, they were not valid because the concordance between observer estimates and video estimates was not greater than would be expected by chance. Manta tow estimates of the cover of sand and rubble were biased in that they consistently overestimated sand and rubble cover in comparison with estimates from video. The results indicate that manta towing is generally effective for the broadscale estimation of live coral cover, providing observers receive adequate training.
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  • 2
    ISSN: 1432-1114
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The Flow Visualization Gun (FVG), a novel time line visualization technique, has been used to investigate the flow field of a helicopter rotor with swept back tip shape in hover flight condition. After introducing the FVG-technique, the paper presents some visualization photographs of the rotor blade tip vortices and the rotor downwash. Using orthogonal sets of flow photographs and digital image analysis, the 3-dimensional time line displacement within the flow and the tip vortex structure are determined. The data of 16 time line experiments are interpolated in space and time to obtain velocity data on an evenly spaced 3-dimensional grid. Vorticity contour plots of the flow field show the complex arrangement of the tip vortices of the blade itself and of the preceding blade and some additional vorticity in the direct wake which may form a secondary vortex. Understanding and control of this vorticity distribution is important for the design of new efficient tip shapes. While the FVG technique has been used so far for qualitative investigation of complex flow patterns at local velocities of up to 20 m/s, a good comparison to laser velocimetry data validates the technique as an interesting tool for both qualitative and quantitative investigation.
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  • 3
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract  Cordierite powder was synthesized via different sol-gel procedures. The use of 29Si NMR spectra of all stages beginning from tetraethoxysilane (TEOS) up to final ceramic powder material is discussed. In the early stages of the sol-gel process all oligomeric structure units can be identified. Spectra of the higher condensed sols only allow the quantification of Qn-groups. MAS spectra of gels heated up to 750 °C show no fine structure to be evaluated. Spectra of samples heated to 1250 °C indicate a sluggish disorder-order transformation from hexagonal α-cordierite to orthorhombic cordierite.
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  • 4
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract  If qualitative analysis is aimed to detect large, imprecisely confined groups comprising hundreds or thousands of compounds – like during the analysis of questionable poisoning cases without direct hints, the so called “general unknowns”–, the evaluation of the identification certainty becomes equally important like the associated estimation of the necessary information capacity of the analytical procedures to be applied [1–4]. On this basis, the authors have outlined factors, which influence the usable information provided by analytical principles or procedures depending of the number and types (analytical categories, differences and similarities, detectability) of the analytes to be detected or included. A correlation between the usable information (excess or deficiency) and the probability of failing identifications is defined, and the information loss by interfering analytical signals is discussed. The concepts of discrimination power DP, identification power IP, and mean list length MLL [4–7] are associated with these considerations. Examples of analytical tasks in this “general unknown” environment of toxicological analysis are presented.
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  • 5
    ISSN: 1432-1041
    Keywords: Key wordsProstaglandin E1 ; Carbonyl reductase; 13 ; 14-dihydro-15-keto-PGE1 ; 13 ; 14-dihydro-PGE1 ; human ; liver ; erythrocytes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract Objective: The therapeutic response to PGE1 is highly variable, and a contribution by variable formation of its active tertiary metabolite PGE0 is in question. Hence, the objective of this study was to assess the person-to-person variation of the reduction of the inactive intermediate metabolite 15-KD PGE1 by human liver and human erythrocytes in forming the active metabolite PGE0. Methods: Source of enzyme was lysed erythrocytes from 29 donors, and a bank of 37 donor livers including specimens from 15 children. Tritium-labelled 13,14-dihydro-15-keto-prostaglandin E1 (15-KD PGE1) was used at low nanomolar concentrations and found to be converted almost exclusively to the more polar compound 13,14-dihydro-prostaglandin E1 (PGE0) by an NADPH-dependent carbonyl reductase. The identity of the product PGE0 was established by comparison of its chromatographic and mass spectral characteristics with authentic PGE0. Results: Lysed erythrocytes had readily measurable enzymatic activity; differences between the preparations from 29 subjects were very small with only a twofold range of variation. In contrast to lysed erythrocytes, intact erythrocytes did not catalyse the reaction so that the erythrocyte activity should be medically immaterial. 15-KD PGE1 15-ketoreductase activity of liver cytosol averaged 61.1 fmol · min−1 · mg−1 protein in preparations from 37 human livers. Individual activities varied over an almost tenfold range, with indications of a non-normal distribution. Kinetic studies of selected specimens showed substantially different Vmax values but indistinguishable k M values, suggesting that the individual variation in 15-KD PGE1 15-ketoreduction is the result of differences in enzyme concentration rather than of structural enzyme variations. The activity in 15 livers from children was significantly lower than in those from adults. Inhibition data suggest that both the liver and the erythrocyte enzymes belong to the class of carbonyl reductases. Conclusions: The variations in hepatic enzyme activity may be expected to affect the transformation of 15-KD PGE1 to the active metabolite PGE0 in vivo. The clinical significance remains to be explored.
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  • 6
    ISSN: 1432-5411
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. The proton-deuteron breakup cross sections and analyzing powers A y for three kinematically complete configurations in a quasi-free-scattering geometry have been measured at E lab P = 65 MeV. The data are compared with predictions of rigorous Faddeev calculations using the Argonne AV14, Bonn-B, Nijmegen-78, and Paris potentials. A satisfactory agreement between theory and experimental data, both for cross sections and analyzing powers, has been found.
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  • 7
    ISSN: 1433-4909
    Keywords: Key words Catechol 2 ; 3-dioxygenase ; Bacillus thermoleovorans ; Thermophilic ; Enzyme stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Catechol 2,3-dioxygenase from the thermophilic Bacillus thermoleovorans A2 was purified and characterized. The catechol 2,3-dioxygenase has a molecular mass of 135 000 Da and consists of four identical subunits of 34 700 Da. One iron per enzyme subunit was detected using atom absorption spectroscopy. Enzyme activity was not inhibited by EDTA, suggesting that the iron is tightly bound. Addition of hydrogen peroxide to the enzyme completely destroyed activity, indicating that the iron was in the divalent state. The isoelectric point of the enzyme was 4.8. The enzyme displayed optimal activity at pH 7.2 and 70°C. The half-life of the catechol 2,3-dioxygenase at the optimum temperature was 1.5 min under aerobic conditions and 10 min in a nitrogen atmosphere. This stability of the enzyme is comparable to the stability of the enzyme from the mesophilic Pseudomonas putida mt-2. The stability of the cloned enzyme in E. coli extracts was identical to the stability in wild-type extracts, suggesting that no stabilizing factors were present in Bacillus thermoleovorans A2 In whole cells the half-life of the enzyme at 70°C was approximately 26 min, when protein synthesis was disrupted by chloramphenicol; however, the activity remained constant when protein synthesis was not inhibited. From these results we concluded that catechol 2,3-dioxygenase from Bacillus thermoleovorans A2 is not particularly thermostable, but that the organism retains the ability to degrade phenol at high temperatures because of continuous production of this enzyme.
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  • 8
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract When transformed with a recombinant vector carrying the ubiC gene (encoding chorismate pyruvate-lyase, EC 4.1.3.27) the triple mutant (Phe−, Trp−, Tyr−) Klebsiella pneumoniae 62-1 excretes 4-hydroxybenzoic acid instead of chorismic acid. The recombinant strain can be used to produce in high yield specifically ring-labelled 4-hydroxybenzoic acid from isotopically labelled glucose.
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  • 9
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Ralstonia eutropha (formerly Alcaligenes eutrophus) JMP 134 was continuously grown on phenol and 2,4-dichlorophenoxyacetate at elevated levels of stationary substrate concentration by using the nutristat principle in order to study the physiological impact exerted by these toxic substrates. Growth at stationary concentrations of both the substrates resulted in the reduction of growth efficiency and growth rate. The growth yield data revealed a pronounced dependence on the substrate concentration, and the growth yield increasingly diminished with rising substrate concentration. Inhibition was more pronounced with 2,4-dichlorophenoxyacetate, which reduced the growth yield coefficient by 50% at a substrate concentration of 0.1–0.25 mM. The same effect was obtained with phenol at about 5 mM. The growth rate profile had two distinct phases: after an initially strong reduction, the rate levelled-off at higher substrate concentrations. Standardizing the inhibition profiles, by taking into account the maximum effect after extrapolating the data to zero growth yield, revealed an almost identical pattern with both substrates, indicating some common mechanism. The growth yield data show that an increased amount of energy is required for both growth and maintenance. Homeostatic work was increased by a factor of 8 at 75% inhibition; growth collapsed once this amount of energy was no longer available. The effects are discussed with respect to the properties of these substrates functioning as potential uncouplers of energy conservation.
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  • 10
    ISSN: 1432-0649
    Keywords: PACS: 42.80; 85.30; 878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: -11  M without separation steps.
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