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  • Escherichia coli  (3)
  • MECHANICAL ENGINEERING  (3)
  • 1985-1989  (6)
  • 1935-1939
  • 1
    Electronic Resource
    Electronic Resource
    Effects of copper concentration in continuous culture on the aa 3-type cytochrome oxidase and respiratory chains of Paracoccus denitrificans (1989)
    Springer
    Archives of microbiology 151 (1989), S. 300-306 
    Details
    ISSN: 1432-072X
    Keywords: Copper-limitation ; Escherichia coli ; Cytochrome oxidases ; Oxygen reduction ; Respiratory chains
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The role(s) of copper in a bacterial cytochrome oxidase of the aa 3-type was investigated by growth of Paracoccus denitrificans NCIB 8944, in batch and steady state continuous culture, in a medium from which the bulk of the copper had been extracted. In a medium containing approximately 0.02 μM copper, cellular copper content, cytochromes a+a 3 and cytochrome a 3 were reduced to 55%, 58% and 33% respectively of control values and there were also less marked decreases in cytochromes c+c 1 (to 85%) and a CO-binding b-type cytochrome, possibly cytochrome o (to 71%). Copper deficiency elicited in reduced minus oxidized difference spectra a shift to shorter wavelengths and narrowing of the band width of the α-band of the oxidase, and loss of a (negative) band near 830 nm attributable to CuA (the copper functionally associated with haem a in the oxidase complex). The oxidase in copper-deficient cells reacted with oxygen to form the oxy “Compound A” at rates similar to that in control cells but CO recombination to ferrous haem a 3 was slowed 4-fold in the copper deficient case. The results are interpreted as indicating loss of CuA and changes in the proportions of haems a and a 3 with retention of catalytic activity. Titrations of respiration rates with antimycin suggested that copper deficiency did not result in diversion of electron flux through an antimycin A-insensitive, cytochrome o-terminated branch of the respiratory chain.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00406555
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Effects of iron-limitation ofEscherichia coli on growth, the respiratory chains and gallium uptake (1986)
    Springer
    Archives of microbiology 146 (1986), S. 80-86 
    Details
    ISSN: 1432-072X
    Keywords: Iron-limitation ; Escherichia coli ; Respiratory chains ; Cytochromes ; Gallium ; Metal uptake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effects of iron limitation on growth, the composition and function of the respiratory chains, and gallium uptake inEscherichia coli have been studied. Decreasing the iron concentration in a defined medium using Chelex resin gave lower growth yields in both continuous culture and prolonged batch culture. In the former, ironlimited (entering [Fe]≤2.0 μM) cells exhibited diminished respiration rates, respiration-driven proton translocation quotients, and levels of non-haem iron and cytochromes. The cellular concentration of haemoproteinb-590 (a cytochromea 1-like hydroperoxidase) decreased 20-fold on iron limitation, whilst a CO-binding pigment with an absorption maximum in the dithionite-treated form near 500 nm appeared. Gallium(III) (9 μM) added to iron-limited, but not iron-sufficient, cultures diminished growth yields further; cells grown with low entering concentrations of iron took up less gallium than iron-sufficient cells. These results are attributed to the interference by gallium(III) with siderophore-mediated metal uptake. Gallium also stimulated iron uptake and was itself accumulated by iron-sufficient cells, suggesting that gallium(III) also affects the iron transport system(s) of low affinity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00690163
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  • 3
    Electronic Resource
    Electronic Resource
    Identification of the promotors directing in vivo expression of hemolysin genes in Proteus vulgaris and Escherichia coli (1988)
    Springer
    Molecular genetics and genomics 213 (1988), S. 99-104 
    Details
    ISSN: 1617-4623
    Keywords: Promoters ; Escherichia coli ; Proteus vulgaris ; Hemolysin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The hemolytic activity of Escherichia coli and Proteus vulgaris is determined by common contiguous genes encoding synthesis (hly C, hly A) and specific secretion (hly B, hly D) of active hemolysin. Nevertheless, the hlyC-proximal DNA sequences directing production of the homologous hemolysins by the recombinant DNAs P. vulgaris pVU763-709 and E. coli pANN202-312 showed no extensive homology. Primer extension and S1 nuclease protection were used to define in the two sequences the 5′ termini of hly transcripts synthesized in vivo and thus to infer the active hly promoters sequences. The E. coli hly C upstream region contained three separate promotors directing in vivo hly transcription, while the corresponding transcription of the P. vulgaris hly operon originated from a single distinct promotor, the-35 and-10 sequences of which formed part of an inverted repeat sequence. Elevated hemolytic activity caused by upstream Tn5 insertions in pVU763-709 resulted from increased transcription from this promotor.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00333404
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  • 4
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    Turbulent two-phase flow in annular seals (1986)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Steady, turbulent two-phase fluid flow in a rotating annular seal with no eccentricity is analyzed. The fluid is assumed to be a homogeneous mixture of liquid and vapor in thermodynamic equilibrum. Further, the flow is assumed to be adiabatic, but the effects due to heat generation by viscous dissipation are accounted for fully. Solution of the model governing differential equations is accomplished by use of a fourth-order Runge-Kutta numerical integration scheme. The calculation of mass leakage rates under choked and unchoked conditions are discussed and the phenomenon of all-liquid choked flow is explained. Several numerical examples are presented supposing cyrogenic oxygen as the sealed fluid.
    Keywords: MECHANICAL ENGINEERING
    Type: ASLE PREPRINT 86-AM-4G-3
    Format: text
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  • 5
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    Dynamics of face and annular seals with two-phase flow (1988)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A detailed study was made of face and annular seals under conditions where boiling, i.e., phase change of the leaking fluid, occurs within the seal. Many seals operate in this mode because of flashing due to pressure drop and/or heat input from frictional heating. Some of the distinctive behavior characteristics of two phase seals are discussed, particularly their axial stability. The main conclusions are that seals with two phase flow may be unstable if improperly balanced. Detailed theoretical analyses of low (laminar) and high (turbulent) leakage seals are presented along with computer codes, parametric studies, and in particular a simplified PC based code that allows for rapid performance prediction: calculations of stiffness coefficients, temperature and pressure distributions, and leakage rates for parallel and coned face seals. A simplified combined computer code for the performance prediction over the laminar and turbulent ranges of a two phase flow is described and documented. The analyses, results, and computer codes are summarized.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-CR-183352 , NAS 1.26:183352
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 6
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    Centrifugal inertia effects in two-phase face seal films (1987)
    In:  Other Sources
    Details
    Publication Date: 2019-07-12
    Description: A simplified, semianalytical model has been developed to analyze the effect of centrifugal inertia in two-phase face seals. The model is based on the assumption of isothermal flow through the seal, but at an elevated temperature, and takes into account heat transfer and boiling. Using this model, seal performance curves are obtained with water as the working fluid. It is shown that the centrifugal inertia of the fluid reduces the load-carrying capacity dramatically at high speeds and that operational instability exists under certain conditions. While an all-liquid seal may be starved at speeds higher than a 'critical' value, leakage always occurs under boiling conditions.
    Keywords: MECHANICAL ENGINEERING
    Type: ASLE Transactions (ISSN 0569-8197); 30; 177-186
    Format: text
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