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  • Springer  (39)
  • Oxford University Press  (3)
  • Wiley  (1)
  • American Meteorological Society (AMS)
  • Springer Science + Business Media
  • 1995-1999  (43)
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Keywords
Publisher
Years
Year
  • 1
    Electronic Resource
    Electronic Resource
    Calculation of carbon balances for evaluation of the biodegradability of polymers (1995)
    Springer
    Journal of polymers and the environment 3 (1995), S. 121-131 
    Details
    ISSN: 1572-8900
    Keywords: Biodegradation ; poly(β-hydroxybutyrate) ; testing ; carbon balance ; carbon dioxide evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Establishing carbon balances has been proven to be an applicable and powerful tool in testing biodegradability of polymers. In controlled degradation tests at a 4-L scale with the model polymer poly(β-hydroxybutyrate) (PHB), it was shown that the degree of degradation could not be determined with satisfactory accuracy from CO2 release alone. Instead, the course of degradation was characterized by means of establishing carbon balances for the degradation of PHB withAcidovorax facilis and a mixed culture derived from compost. Different analytical methods for determining the different carbon fractions were adapted to the particular test conditions and compared. Quantitative determination of biomass and residual polymer were the main problems in establishing carbon balances. Amounts of biomass derived from protein measurements depend strongly on assumptions of the protein content of the biomass. Selective oxidation of biomass with hypochlorite was used as alternative, but here problems arose from insoluble metabolic products. Determination of soluble components with the method of chemical oxygen demand (COD) also includes empirical assumptions but seems acceptable if the dissolved carbon fraction is in the range of some 10% total carbon. Results confirm both analytical assays and theoretical approaches, in ending up at values very close to 100%, within an acceptable standard deviation range under test conditions comparable to standard test practice.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02068463
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  • 2
    Electronic Resource
    Electronic Resource
    Evaluation of the biodegradability of copolyesters containing aromatic compounds by investigations of model oligomers (1996)
    Springer
    Journal of polymers and the environment 4 (1996), S. 9-20 
    Details
    ISSN: 1572-8900
    Keywords: Copolyesters ; biodegradability ; aliphatic diol ; adipic acid ; terephthalic acid ; aromatic oligomers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Model oligo esters of terephthalic acid with 1,2-ethanediol, 1,3-propanediol, and 1,4-butanediol have been investigated with regard to their biodegradability in different biological environments. Well-characterized oligomers with weight-average molar masses of from 600 to 2600 g/mol exhibit biodegradation in aqueous systems, soil, and compost at 60°C. SEC investigations showed a fast biological degradation of the oligomer fraction consisting of 1 or 2 repeating units, independent of the diol component used for polycondensation, while polyester oligomers with degrees of polymerization higher than 2 were stable against microbial attack at room temperature in a time frame of 2 months. At 60°C in a compost environment chemical hydrolysis also degrades chains longer than two repeating units, resulting in enhanced degradability of the oligomers. Metabolization of the monomers and the dimers as well by the microorganisms could be confirmed by comparing SEC measurements and carbon balances in a “Sturm test” experiment. Based on these results degradation characteristics of potential oligomer intermediates resulting from a primary chain scission from copolyesters consisting of aromatic and aliphatic dicarbonic acids can be predicted depending on their composition. These results will have an evident influence on the evaluation of the biodegradability of commercially interesting copolyesters and lead to new ways of tailor-made designing of new biodegradable materials as well.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02083878
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  • 3
    Electronic Resource
    Electronic Resource
    Catechol 2,3-dioxygenase from the thermophilic, phenol-degrading Bacillus thermoleovorans strain A2 has unexpected low thermal stability (1999)
    Springer
    Extremophiles 3 (1999), S. 185-190 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s007920050115
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  • 4
    Electronic Resource
    Electronic Resource
    Detection and identification of individual antigen molecules in human serum with pulsed semiconductor lasers (1997)
    Springer
    Applied physics 65 (1997), S. 427-431 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003400050292
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  • 5
    Electronic Resource
    Electronic Resource
    Laser frequency stabilization using selective reflection spectroscopy (1998)
    Springer
    Applied physics 66 (1998), S. 323-326 
    Details
    ISSN: 1432-0649
    Keywords: PACS: 06.20.F; 42.62.F; 78.40
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: 1 line. We discuss the performance of this novel frequency stabilization scheme and analyze its dependence on various system parameters. The technique is compared to the commonly used saturation spectroscopic techniques.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003400050395
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  • 6
    Electronic Resource
    Electronic Resource
    Prevalence of Trabecular Microcallus Formation in the Vertebral Body and the Femoral Neck (1997)
    Springer
    Calcified tissue international 60 (1997), S. 479 -484 
    Details
    ISSN: 1432-0827
    Keywords: Key words: Trabecular microcallus formation — Vertebra — Femur — Histomorphometry — Bone density — Osteoporosis.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract. Trabecular microcallus formation (TMF) has been described previously in the human vertebra and femur, but the difference in TMF prevalence at these two sites has not been studied and the role of TMF remains controversial. In this study, the 4th lumbar vertebra (L4) and right proximal femur were removed from 27 male and 23 female cadavers. A 2 cm cube cut from the center of L4 and a 1 cm-thick slice cut from the femoral neck were cleaned, defatted, and dried. The apparent density of the L4 cubes was determined as dry weight/bulk bone volume. Using a dissecting microscope at low magnification (4–60×), TMF were identified and counted in both the vertebral and femoral samples. A 8 mm diameter core was then cut from the center of the L4 cubes in the vertical direction, and selected histomorphometric parameters of the core were evaluated with an X-ray microcomputed tomography system (μ-CT). There was a significantly greater prevalence of TMF in vertebral cubes (82%) than in the femoral slices (11%) (P 〈 0.001). TMF prevalence did not differ significantly between males and females, but the mean number of TMF in the vertebra was significantly (P 〈 0.05) greater in females (15.0/vertebra) than in males (7.7/vertebra). In the vertebra, the majority of the observed TMF were in vertical trabeculae. Subjects over 60 years old had a higher TMF prevalence than those under 60 years old (P 〈 0.01). TMF numbers increased with decreasing apparent density (P 〈 0.05), whereas no significant correlations were found between TMF and bone volume (BV/TV), trabecular number (Tb.N), or trabecular thickness (Tb.Th) as assessed by μ-CT. In two fractured vertebra, very few TMFs (2 and 4, respectively) were observed. These results demonstrated that the occurrence of TMF is strongly related to the anatomical site, probably due to differences in the applied loads and the trabecular structure between sites. The results were consistent with the hypothesis that TMF is a mechanism acting to maintain bone strength, but further studies are needed to clarify this important issue.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002239900266
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  • 7
    Electronic Resource
    Electronic Resource
    Validity and reproducibility of benthic cover estimates made during broadscale surveys of coral reefs by manta tow (1999)
    Springer
    Coral reefs 18 (1999), S. 353-356 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003380050212
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  • 8
    Electronic Resource
    Electronic Resource
    Proton-Induced Deuteron Breakup at E lab P = 65 MeV in Quasi-Free Scattering Configurations (1996)
    Springer
    Few body systems 20 (1996), S. 27-40 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s006010050029
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  • 9
    Electronic Resource
    Electronic Resource
    Microbial production of specifically ring-13C-labelled 4-hydroxybenzoic acid (1995)
    Springer
    Applied microbiology and biotechnology 43 (1995), S. 985-988 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00166913
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  • 10
    Electronic Resource
    Electronic Resource
    Substrate inhibition under stationary growth conditions – nutristat experiments with Ralstonia eutropha JMP 134 during growth on phenol and 2,4-dichlorophenoxyacetate (1997)
    Springer
    Applied microbiology and biotechnology 48 (1997), S. 648-655 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002530051110
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