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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 80 (1996), S. 2367-2371 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Lithiated Sn oxide films, denoted LixSnO2, were produced by reactive rf magnetron sputtering of Sn and electrochemical post-treatment. Optical transmittance and Mössbauer spectra were recorded for progressively increased lithiation. Increasing x from zero to ∼0.1 did not have any significant effect on the optical data or Mössbauer spectra, and it is likely that the lithium is located in internal double layers in the film. Further increasing x from ∼0.1 to ∼0.2 yielded significant transmittance drops and Mössbauer spectra unambiguously showing a conversion Sn4+→Sn2+. Hence the optical absorption can be reconciled with intervalency transitions as in other cathodically coloring electrochromic oxides. Electrocrystallization appeared to dominate the electrochemistry at x(approximately-greater-than)0.2. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Applied microbiology and biotechnology 43 (1995), S. 1006-1013 
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Insect cell metabolism was studied in substrate-limited fed batch cultures of Spodoptera frugiperda (Sf-9) cells. Results from a glucose-limited culture, a glutamine-limited culture, a culture limited in both glucose and glutamine and a batch culture were compared. A stringent relation between glucose excess and alanine formation was found. In contrast, glucose limitation induced ammonium formation, while, at the same time, alanine formation was completely suppressed. Simultaneous glucose and glutamine limitation suppressed both alanine and ammonium formation. Although the metabolism was influenced by substrate limitation, the specific growth rate was similar in all cultures. Alanine formation must involve incorporation of free ammonium, if ammonium formation is mediated by glutaminase and glutamate dehydrogenase, as our data suggest. On the basis of the results, two possible pathways for the formation of alanine in the intermediary metabolism in insect cells are suggested. The cellular yield on glucose was increased 6.6 times during glucose limitation, independently of the cellular yield on glutamine, which was increased 50–100 times during glutamine limitation. The results indicate that alanine overflow metabolism is energetically wasteful and that glutamine is a dispensable amino acid for cultured Sf-9 cells. Preliminary data confirm that glutamine can be synthesised by the cells themselves in amounts sufficient to support growth.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Bioprocess and biosystems engineering 7 (1991), S. 47-51 
    ISSN: 1432-0797
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract A Flow Injection Analysis method for determination of the enzyme β-galactosidase produced in a fermentation process has been developed. The analytical range was 10–1000 U/cm3 and the sample throughput was 40 h−1. The FIA set up was connected directly to the down-stream process and the enzyme activity in the extraction step was measured on-line. The viscosity of the samples from the process is high causing certain physical effects on the FIA system.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1862-0760
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Sn oxide films were made by reactive rf magnetron sputtering under conditions that led to both electronic and ionic conductivity. The film structure was studied by X-ray diffraction and Atomic Force Microscopy (AFM). Li+ intercalation produced electrochromism with coloration efficiency peaked in the infrared. Cyclic voltammograms taken at different sweep rates were interpreted in terms of a unique structural parameter related to the fractal dimension of a self-affine surface relief and in excellent agreement with the fractal dimension as obtained with AFM. Mössbauer spectroscopy was used to determine the valence state of the Sn-atoms; a change from Sn4+ to Sn2+ was detected after electrochemical intercalation of Li+.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 47 (1995), S. 139-146 
    ISSN: 0006-3592
    Keywords: Escherichia coli ; fed-batch ; acetate ; glucose ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A Large bioreactor is an inhomogenous system with concentration gradients which depend on the fluid dynamics and the mass transfer of the reactor, the feeding strategy, the saturation constant, and the cell density. The responses of Escherichia coli cells to short-term oscillations of the carbon/energy substrate in glucose limited fed-batch cultivations were studied in a two-compartment reactor system consisting of a stirred tank reactor (STR) and an aerated plug flow reactor (PFR) as a recycle loop. Short-term glucose excess or starvation in the PFR was simulated by feeding of glucose to the PFR or to the STR alternatively. The cellular response to repeated short-term glucose excess was a transient increase of glucose consumption and acetate formation. But, there was no accumulation of acetate in the culture, because it was consumed in the STR part where the glucose concentration was growth limiting. However, acetate accumulated during the cultivation if the oxygen supply in the PFR was insufficient, causing higher acetate formation. The biomass yield was then negatively influenced, which was also the case if the PFR was used to simulate a glucose starvation zone. The results suggest that short-term heterogeneities influence the cellular physiology and growth, and can be of major importance for the process performance. © 1995 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Hyperfine interactions 10 (1981), S. 867-872 
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Hyperfine interactions 23 (1985), S. 109-124 
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Three crystallographically different structures of (Fe1−xVx)3 Ge have been studied by57Fe Mössbauer spectroscopy. The hexagonal phase, stable for low values ofx, is ferromagnetic with the spins parallel to thec-axis above a critical temperature, where a spin flip to thec-plane takes place. A V/Fe substitution in the near surrounding of an iron atom leads to a decrease in the isomer shift of −0.02 mm/s and an estimated reduction in the magnetic moment of 0.31μ B from 2.07μ B. A result for the intermediate cubic closed packed structure is that V populates only one type of metal sites. Furthermore, from similarities withα-Fe the average value of the change in isomer shift is found to be +0.075 mm/s and +0.02 mm/s per Ge/Fe substitution in the 1nn and 2nn shells, respectively. The spin polarization effect on the magnetic hyperfine field for iron is −8.6%, −0.4%, and −0.6% per Ge/Fe (1nn), Ge/Fe (2nn) and V/Fe (3nn) substitutions, respectively. The simple cubic compound (Fe0.7V0.3)3 Ge is non-magnetic down to at least 5 K. Here a decrease in the isomer shift of −0.05 mm/s is found for a V/Fe (1nn) substitution.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Hyperfine interactions 54 (1990), S. 563-566 
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract TlFe2−x Se2 compounds withx from 0.36 to 0.40 have been examined with Mössbauer spectroscopy. The compounds order antiferromagnetically with broad magnetic transition regions whose width increases with decreasing Fe content. The Néel temperature decreases with x and the temperature variation of the magnetic hyperfine field indicates that the transition is of first order. In samples without vacancy ordering the Fe nuclei experience a different temperature variation of the hyperfine field than in compounds with ordered vacancies.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Mössbauer spectroscopic studies (57Fe) of powdered magnetite have been undertaken between 120 K and 880 K. Below the magnetic transition temperature (T C=839.5 K) three six-line patterns have been fitted to our experimental spectra. The broadening of the B-pattern is explained by two magnetically non-equivalent B-site irons, suggesting broadening due to electron hopping to be negligible. In the paramagnetic state the electric quadrupole splittings of iron at A-and B-sites are found to be constant, independent of temperature, having the values zero and 0.16 mm/s, respectively. The centroid shifts, on the other hand, show above 700 K large deviations from the calculated second order Doppler shift. It is proposed that the deviations arise from a variation in band overlap. The temperature variation of the magnetic fields is found to be proportional to the sublattice magnetization. The difference in the magnetic fields at the two non-equivalent B-sites is measured to be 1.1 T at 310 K.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Hyperfine interactions 34 (1987), S. 447-449 
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The57Fe Mössbauer spectra of FeMnP show a remarkable magnetic distribution for T 175K, although all iron atoms are crystallographically equivalent. It seems possible to explain this distribution by a spin modulation described by coexistence of an antiferro — and a helimagnetic probe. A theoretical calculation performed, justifies this explanation.
    Type of Medium: Electronic Resource
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