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  • 1
    Electronic Resource
    Electronic Resource
    Enzymic arrangement and allosteric regulation of the aromatic amino acid pathway in Neisseria gonorrhoeae (1987)
    Springer
    Archives of microbiology 149 (1987), S. 87-94 
    Details
    ISSN: 1432-072X
    Keywords: Neisseria gonorrhoeae ; Biochemical evolution ; Aromatic biosynthesis ; Regulatory enzymes ; Superfamily A ; Bacterial phylogeny
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The pathway construction and allosteric regulation of phenylalanine and tyrosine biosynthesis was examined in Neisseria gonorrhoeae. A single 3-deoxy-d-arabino-heptulosonate 7-phosphate (DAHP) synthase enzyme sensitive to feedback inhibition by l-phenylalanine was found. Chorismate mutase and prephenate dehydratase appear to co-exist as catalytic components of a bifunctional enzyme, known to be present in related genera. The latter enzyme activities were both feedback inhibited by l-phenylalanine. Prephenate dehydratase was strongly activated by l-tyrosine. NAD+-linked prephenate dehydrogenase and arogenate dehydrogenase activities coeluted following ion-exchange chromatography, suggesting their identity as catalytic properties of a single broad-specificity cyclohexadienyl dehydrogenase. Each dehydrogenase activity was inhibited by 4-hydroxyphenylpyruvate, but not by l-tyrosine. Two aromatic aminotransferases were resolved, one preferring the l-phenylalanine:2-ketoglutarate substrate combination and the other preferring the l-tyrosine: 2-ketoglutarate substrate combination. Each aminotransferase was also able to transaminate prephenate. The overall picture of regulation is one in which l-tyrosine modulates l-phenylalanine synthesis via activation of prephenate dehydratase. l-Phenylalanine in turn regulates early-pathway flow through inhibition of DAHP synthase. The recent phylogenetic positioning of N. gonorrhoeae makes it a key reference organism for emerging interpretations about aromatic-pathway evolution.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00425071
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  • 2
    Electronic Resource
    Electronic Resource
    Energy use in spawning Atlantic salmon (2004)
    Oxford, UK : Munksgaard International Publishers
    Ecology of freshwater fish 13 (2004), S. 0 
    Details
    ISSN: 1600-0633
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract –  We studied some of the factors that might influence energy use in spawning Atlantic salmon (Salmo salar). Single females were placed into an experimental channel with either one or three males, after which spawning was monitored continuously. Male status was confirmed using genetic parentage analysis. Daily fat loss was monitored with the Torry Fish Fatmeter and validated through biochemical analyses. Several comparisons were in the expected direction but not statistically significant and therefore require further study: daily fat loss appeared higher for dominant males relative to subordinate males and in the three-male treatment relative to the one-male treatment. Most of the variation among individuals remained unexplained, suggesting that several as yet unknown factors strongly influence fat loss in spawning salmon. A large and significant effect was that daily fat loss was higher for females than for males, a difference that might contribute to the shorter spawning duration typical of females.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1600-0633.2004.00045.x
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  • 3
    Electronic Resource
    Electronic Resource
    A study of voluntary intake and digestibility of roughages in relation to their degradation characteristics and retention time in the rumen
    Amsterdam : Elsevier
    Animal Feed Science and Technology 43 (1993), S. 227-237 
    Details
    ISSN: 0377-8401
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/0377-8401(93)90079-Y
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  • 4
    Electronic Resource
    Electronic Resource
    Nitriding of stainless steel in an rf plasma (1989)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 66 (1989), S. 5598-5601 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Treatment of stainless steels in an rf-powered nitrogen plasma achieves a much increased rate of nitriding, as well as higher hardness and corrosion resistance than traditional nitriding. Small amounts of adsorbed hydrogen are found to be necessary initially, and the process of nitriding is modeled on the basis of this hydrogen increasing the surface sticking coefficient for nitrogen, which is followed by nitrogen diffusion into bulk in the form of nitrogen-vacancy (weakly bound) pairs. The detailed microstructural role of chromium in the process is also discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.343664
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  • 5
    Electronic Resource
    Electronic Resource
    Observation of quantum interference effects and SQUID operation in a bulk sample of YBa2Cu3Oy at 77 and 4.2 K (1987)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 51 (1987), S. 1364-1366 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have studied the response of a bulk sample of YBa2Cu3Oy to an applied static magnetic field B and a 20-MHz rf field. At both 77 and 4.2 K we found clear evidence of behavior within the sample that was characteristic of a superconducting quantum interference device. At 77 K, the absorption of rf power was a periodic function of B, characterized by several superposed periods in the range 8×10−8 to 9×10−6 T. At 4.2 K only one period, of 4.8×10−7 T, was evident. By applying flux feedback we could lock to minima in the response, and in this mode of operation as a magnetometer the field spectral density S1/2B was 1.5×10−10 T Hz−1/2 at 77 K and 5.8×10−10 T Hz−1/2 at 4.2 K.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.98680
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  • 6
    Electronic Resource
    Electronic Resource
    The role of titanium in the abrasive wear resistance of physically vapour-deposited TiN
    Amsterdam : Elsevier
    Surface & Coatings Technology 41 (1990), S. 63-74 
    Details
    ISSN: 0257-8972
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0257-8972(90)90130-5
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  • 7
    Electronic Resource
    Electronic Resource
    The abrasive wear resistance of sputter ion plated titanium nitride coatings
    Amsterdam : Elsevier
    Surface & Coatings Technology 36 (1988), S. 743-754 
    Details
    ISSN: 0257-8972
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0257-8972(88)90014-X
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  • 8
    Electronic Resource
    Electronic Resource
    Room temperature, visible wavelength optical bistability in ZnSe interference filters
    Amsterdam : Elsevier
    Optics Communications 51 (1984), S. 357-362 
    Details
    ISSN: 0030-4018
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0030-4018(84)90026-9
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  • 9
    Electronic Resource
    Electronic Resource
    The biochemical basis for growth inhibition by L-phenylalanine in Neisseria gonorrhoeae (1989)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 3 (1989), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Clinical isolates of Neisseria gonorrhoeae are commonly subject to growth inhibition by phenylpyruvate or by L-phenylalanine. A blockade of tyrosine biosynthesis is indicated since inhibition is reversed by either L-tyrosine or 4-hydroxyphenylpyruvate. Phenylalanine-resistant (PheR) and phenylalanine-sensitive (Phes) isolates both have a single 3-deoxy-D-arabino-heptulosonate 7-phosphate (DAHP) synthase that is partially inhibited by L-phenylalanine (80%). However, PheS and PheR isolates differ in that the ratio of phenylpyruvate aminotransferase to 4-hydroxyphenylpyruvate aminotransferase is distinctly greater in PheS isolates than in PheR isolates. A mechanism for growth inhibition is proposed in which phenylalanine exerts two interactive effects, (i) Phenylalanine decreases precursor flow to 4-hydroxyphenylpyruvate through its controlling effect upon DAHP synthase; and (ii) phenylalanine is largely transaminated to phenylpyruvate, which saturates both aminotransferases, preventing transamination of an already limited supply of 4-hydroxyphenylpyruvate to L-tyrosine.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2958.1989.tb00188.x
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  • 10
    Electronic Resource
    Electronic Resource
    The influence of iron on the preparation of silicon nitride from silica (1985)
    Springer
    Journal of materials science 20 (1985), S. 3230-3238 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The thermodynamics of carbothermal reduction and nitriding of silica in the temperature range 1200 to 1600° C have been evaluated and may be used to determine the conditions required to form silicon nitride, silicon oxynitride or silicon carbide. The products of reaction are, however, frequently dictated by kinetic rather than thermodynamic considerations and the presence of impurities in the silica and carbon reactants is especially important. α-silicon nitride has been prepared from high purity silica and carbon but under identical conditions of temperature and nitrogen pressure the chemistry of the process changes markedly when a small amount of iron is added to the reactants. Below 1320° C iron has no effect and pure α-silicon nitride is formed but with increasing temperature the proportion of silicon carbide in the product increases. Above 1550° C silicon carbide is the stable solid phase in the Si-C-O-N system at 1 atm pressure. The process chemistry has been investigated by high-temperature reaction studies and X-ray diffraction and reaction mechanisms are proposed on the basis of microstructural observations of reactants and products.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00545189
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