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  • 1990-1994  (5)
  • 1985-1989  (3)
  • 1925-1929  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Cellular and molecular life sciences 47 (1991), S. 292-296 
    ISSN: 1420-9071
    Keywords: Pyridine metabolism ; hydroxypyridines ; anaerobiosis ; denitrifying conditions ; sulfate-reducing conditions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The transformation of pyridine and several hydroxypyridines was investigated under different physiological conditions. Pyridine and 2-, 3- and 4-hydroxypyridine were metabolized aerobically within 9 days in a mineral salt medium inoculated with 10% sewage sludge. Under anaerobic conditions in the presence of nitrate or sulfate, pyridine and 3-hydroxypyridine were metabolized after a lag period of 2 months, while no transformation of 2- or 4-hydroxypyridine was detected. Experiments with14C-labeled-pyridine showed that under denitrifying as well as under sulfate-reducing conditions pyridine was oxidized to carbon dioxide. Disappearance of nitrate and sulfate under anaerobic conditions was 79% and 85%, respectively, of the amount predicted from the stoichiometric equation for the complete transformation of pyridine.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Cellular and molecular life sciences 46 (1990), S. 797-806 
    ISSN: 1420-9071
    Keywords: Aquifers ; groundwater ; deep subsurface microorganisms ; eukaryotes ; prokaryotes ; microbial metabolism ; oligotrophic conditions ; xenobiotic compounds
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Little is known about the layers under the earth's crust. Only in recent years have techniques for sampling the deeper subsurface been developed to permit investigation of the subsurface environment. Prevailing conditions in the subsurface habitat such as nutrient availability, soil composition, redox potential, permeability and a variety of other factors can influence the microflora that flourish in a given environment. Microbial diversity varies between geological formations, but in general sandy soils support growth better than soils rich in clay. Bacteria predominate in subsurface sediments, while eukaryotes constitute only 1–2% of the microorganisms. Recent investigations revealed that most uncontaminated subsurface soils support the growth of aerobic heteroorganotrophic bacteria, but obviously anaerobic microorganisms also exist in the deeper subsurface habitat. The microorganisms residing below the surface of the earth are capable of degrading both natural and xenobiotic contaminants and can thereby adapt to growth under polluted conditions.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Applied physics 56 (1993), S. 299-302 
    ISSN: 1432-0630
    Keywords: 72.20 ; 73.40 ; 82.70
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Samples of carbon black loaded nitrile rubber are measured at microwave frequencies (waveguide transmission and reflection). The observed dielectric relaxation is interpreted using a two phase effective medium model (Böttcher formula). The two phases are identified with free rubber as insulating matrix and a conductive filler of a priori unknown parameters (volume fraction, permittivity, conductivity). Supported by SEM and de measurements the results allow to associate the filler phase with adsorbate covered carbon black. In this way the bulk conductivity of carbon black loaded rubber can be explained by (statistical) percolation, which has been not possible taking pure carbon black particles as the percolating elements. Because the effective conductivity of the filler particles deduced from the microwave measurements characterizes mainly the particles' surface it is supposed that the adsorbate may become conductive by the chemical and physical interactions of polymer and carbon black during the preparation of the composite. Reference is made to the doping of rubber resulting in conductivities of the same order of magnitude.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Journal of superconductivity 7 (1994), S. 169-173 
    ISSN: 1572-9605
    Keywords: La2−x Sr x CuO4 ; positron annihilation ; ACAR ; Fermi surface ; Sr doping ; electronic structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract High-statistics (〉4 × 108 counts), room-temperature measurements of the electron-positron momentum density of La2−x Sr x CuO4 have been performed for samples with Sr concentrations of x=0.0, 0.1, 0.13, and 0.2. These spectra have been analyzed in conjunction with theoretical calculations of the electron-positron momentum density. The metallic samples show features consistent with the presence of a Fermi surface, but its evolution with increasing Sr concentration does not follow the predictions of band theory. These results may indicate the effects of electron-electron correlation on the electron momentum distribution in the Cu-O plane.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Graefe's archive for clinical and experimental ophthalmology 116 (1925), S. 288-311 
    ISSN: 1435-702X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Applied physics 39 (1986), S. 15-18 
    ISSN: 1432-0649
    Keywords: 07.60.Fs ; 78.20.Ls ; 42.60.-v
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract To detect small rotation rates with a ring laser the two counter-propagating beams must be uncoupled. This lock-off can be realized using nonreciprocal optical effects yielding different optical path lengths for the two waves. Usually magnetooptical effects are employed for nonreciprocity. To measure, instead of calculating from optical constants, the magnitude of this nonreciprocal effects an ellipsometric method is proposed. Lock-off elements using Faraday or Kerr effect (polar and transverse, respectively) are treated. First measurements were made on FeNi films.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Applied physics 45 (1988), S. 1-5 
    ISSN: 1432-0649
    Keywords: 02.60.Nm ; 07.60.Fs ; 78.20.−e
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The continuous variation of the refractive index with the depth in the vicinity of surfaces can be determined by ellipsometry without destroying the object of measurements. The presented method does not impress any given structure to the profile and is applicable to just the range of layer thicknesses interesting to optics (about λ/4 to λ/2). The theoretical approach to interpret the measured data leads to an integral equation that is numerically inverted by regularization to filter out the destabilizing effects of measurement errors. The regularizing operator and regularization parameter responsible for this “filtering” are founded on physical arguments and experiment, respectively. These results can be transferred to other regularization problems based on quantities related to volume (e.g. density, temperature).
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Contributions to the Chemistry of N-substituted Metal Amides. XIX. Reaction of [Co(NPh2)2]2 with CO - a New Way for the Synthesis of an Chelate Complex of Cobalt (II) with an Derivative of Anthranilic Acid; Molecular Structure of [Co(NPh(o—C6H4CONPh2))2]Reaction of CO (1 atm, room temperature) with [Co(NPh2)2]2 (I) in benzene (mole ratio 3 : 1) gives Co(CO)3(NPh2)4(benzene)1·6 (II). By adding more CO to the reaction mixture (mole ratio 6 : 1) Co4(CO)12 (III) and a dark red compound of the analytical composition C50H38CoN4O2 (IV) could be isolated. The structure of the red compound was determined by X-ray diffraction. This investigation show IV to be a cobalt(II) complex of an derivative of the anthranilic acid, [Co(NPh(o—C6H4CONPh2))2] (IV). The cobalt coordination in this compound is a distorted tetrahedron. Crystal data of IV: space group P1 with a = 12.449(1) Å, b = 12.431(1) Å, c = 13.223(1) Å, α = 95.47(1)°, β = 95.37(1)°, γ = 94.10(1)°, and Z = 2.
    Notes: Bei der Umsetzung von CO (1 atm, Raumtemperatur) mit [Co(NPh2)2]2 (I) in Benzen im Molverhältnis 3 : 1 entsteht Co2(CO)3(NPh2)4(benzen)1,6 (II); im Molverhältnis 6 : 1 bildet sich ein Reaktionsgemisch, aus dem Co4(CO)12 (III) sowie eine dunkelrote Verbindung der analytischen Zusammensetzung C50H38CoN4O2 (IV) isoliert werden kann. Die Röntgenstruktur-bestimmung von IV ergab, daß es sich um den ein Anthranilsäurederivat als Liganden enthaltenden Komplex [Co(NPh(o—C6H4CONPh2))2] IV handelt, der eine verzerrt tetraedrische Koordination aufweist.Kristalldaten für IV: Raumgruppe P1 mit a = 12,449(1) Å, b = 12,431(1) Å, c = 13,223(1) Å, α = 95,47(1)°, β = 95,37(1)°, γ = 94,10(1)° und Z = 2.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 10 (1990), S. 23-34 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: There are many points of contact between optimization problems and modeling. On the one hand the model adjustment process itself as a process of estimation is closely connected with optimization, in that it is to produce what is in one sense the best possible model. The basic structure of the optimization problem as problem in decision making with the necessary input of an objective function is thus evident. On the other hand a model is never an end in itself but on the basis of its simulation capacity a means to an end, for example in biotechnological optimization. From this point of view the model is a product of scientific work and thus an economic value. Equally, through its intended purpose the model exhibits a utility value. A complete evaluation of the model as a condition of rational modeling must take into account both these aspects. That is possible in principle by adding the modeling expenditure to expenditure for the realization of biotechnological processes, expressing the economic consequences of model quality as an objective function, and minimizing the specific total expenditure for the product to be produced.Biotechnological practice requires that the “optimum” model is approached by means of iterative processes. Some practical examples will make the process clear, taking into account qualitative (semantic) and quantitative (accuracy) aspects of the utility value.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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