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  • 1
    Electronic Resource
    Electronic Resource
    In vitro and in vivo regulation of assimilatory nitrite reductase from Candida utilis (1997)
    Springer
    Archives of microbiology 168 (1997), S. 215-224 
    Details
    ISSN: 1432-072X
    Keywords: Key words Candida utilis ; Nitrite reductase ; Electron ; donors ; Cysteine modification ; Transcriptional control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The nitrate assimilation pathway in Candida utilis, as in other assimilatory organisms, is mediated by two enzymes: nitrate reductase and nitrite reductase. Purified nitrite reductase has been shown to be a heterodimer consisting of 58- and 66-kDa subunits. In the present study, nitrite reductase was found to be capable of utilising both NADH and NADPH as electron donors. FAD, which is an essential coenzyme, stabilised the enzyme during the purification process. The enzyme was modified by cysteine modifiers, and the inactivation could be reversed by thiol reagents. One cysteine was demonstrated to be essential for the enzymatic activity. In vitro, the enzyme was inactivated by ammonium salts, the end product of the pathway, proving that the enzyme is assimilatory in function. In vivo, the enzyme was induced by nitrate and repressed by ammonium ions. During induction and repression, the levels of nitrite reductase mRNA, protein, and enzyme activity were modulated together, which indicated that the primary level of regulation of this enzyme was at the transcriptional level. When the enzyme was incubated with ammonium salts in vitro or when the enzyme was assayed in cells grown with the same salts as the source of nitrogen, the residual enzymatic activities were similar. Thus, a study of the in vitro inactivation can give a clue to understanding the mechanism of in vivo regulation of nitrite reductase in Candida utilis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002030050491
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  • 2
    Electronic Resource
    Electronic Resource
    Termitomyces clypeatus controls secretion of extracellular amyloglucosidase by regulating exocytosis of vacuolar enzyme (1998)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 158 (1998), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: An extracellular amyloglucosidase (56 kDa) of Termitomyces clypeatus which was accumulated intracellularly in absence of Krebs cycle acids in dextrin medium, remained mostly inside the plasma membrane. The enzyme was localised in mycelial vacuoles as a sucrase-amyloglucosidase aggregate. The intracellular pool contained both the free sucrase and the aggregate, while vacuoles contained only aggregate without any free enzyme. The aggregate, partially purified to PAGE homogeneity, contained amyloglucosidase and sucrase in the ratio of 1:1. A cellular regulation, influenced by the presence of Krebs cycle acids, was indicated to be present at the level of exocytosis of vacuolar enzyme.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.1998.tb12807.x
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  • 3
    Electronic Resource
    Electronic Resource
    Regulation of protein secretion by mycelial culture of the mushroom Termitomyces clypeatus (1997)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 154 (1997), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Termitomyces clypeatus secreted a 24-kDa xylanase constitutively in xylan medium, but required a gluconeogenic amino acid or Krebs cycle acid for the secretion of a 56-kDa amyloglucosidase in dextrin medium. Aspartate, glutamate, succinate and fumarate all increased secretion of amyloglucosidase from 50% to 〉90% and enzyme production by 10-fold with little effect on xylanase production. Glutamate or succinate stimulated in vitro release of intracellular amyloglucosidase from washed mycelia in the presence of cycloheximide. Amyloglucosidase accumulated in the absence of glutamate was a high-molecular-mass protein that did not migrate in PAGE. Cellular regulation by the fungus of the secretion of amyloglucosidase is indicated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.1997.tb12650.x
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  • 4
    Electronic Resource
    Electronic Resource
    Field-induced phase switching and electrically driven strains in sol-gel derived antiferroelectric (Pb,Nb)(Zr,Sn,Ti)O3 thin layers (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 78 (1995), S. 1171-1177 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Tin-modified lead zirconate titanate thin layers were prepared by a sol-gel method. A room- temperature antiferroelectric (AFE) phase composition Pb0.99Nb0.02[(Zr0.58Sn0.42)0.96Ti0.04] 0.98O3 was prepared and examined for weak- and high-field dielectric properties as a function of temperature, with emphasis on field-induced AFE-ferroelectric (FE) switching characteristics. Thin layers processed with a lead oxide cover coat were found to be free of any secondary phases and showed improved properties. Room-temperature values of dielectric constant K'=390 and saturation polarization Ps=20 μC/cm2 were obtained with field-induced strains up to 0.15% in submicron grain structures. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.360353
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  • 5
    Electronic Resource
    Electronic Resource
    Effect of extremely fine Y2BaCuO5 precipitates on the critical current density of melt-processed YBa2Cu3Ox (1997)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 81 (1997), S. 7396-7408 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Based on previously developed melt processing methods, Y2BaCuO5 (211) precipitates with various size were obtained in YBa2Cu3Ox (123). In particular, a wide distribution of 211 size from 100 Å to 10 μm has been found to exist in the matrix of 123, and strongly effected the critical current density, Jc. An enhancement of Jc was always found to be associated with the presence of extremely fine 211 precipitates. The flux pinning by these precipitates can be understood by considering the interaction of flux lines with cavities. It was found that although the flux lines are strongly pinned by cavities, the effectiveness decreases with the increasing number of flux lines trapped by them. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.365280
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  • 6
    Electronic Resource
    Electronic Resource
    Spectral factorization technique for estimation of an ARMA operator for multichannel deconvolution of seismic data[ Received ] (1997)
    Oxford, UK : Blackwell Science Ltd
    Geophysical prospecting 45 (1997), S. 0 
    Details
    ISSN: 1365-2478
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Physics
    Notes: A new spectral factorization method is presented for the estimation of a causal as well as a causally invertible ARMA operator from the correlation sequence of seismic traces. The method has been implemented for multichannel deconvolution of seismic traces with the aim of exploiting the trace-to-trace correlation that exists within seismograms. A layered earth model with a small reflectivity sequence has been considered, and the seismic traces have been considered as the output of a linear system driven by white noise reflection coefficient sequences.  The present method is the concatenation of three algorithms, namely Kung's method for state variable (F,G,H) realization using a singular value decomposition (SVD) algorithm, Faurre's technique for computation of the strong spectral factor and Leverrier's algorithm for ARMA representation of the spectral factor. The inverted ARMA operator is used as a recursive filter for deconvolution of seismic traces. In the example shown, two traces with a covariance sequence of 160 ms length have been considered for multichannel deconvolution of stacked seismic traces. The results presented, when compared with those obtained from a conventional deconvolution algorithm, have shown encouraging prospects.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2478.1997.3400263.x
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  • 7
    Electronic Resource
    Electronic Resource
    Origins and evolution of stress development in sol-gel derived thin layers and multideposited coatings of lead titanate (1998)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 83 (1998), S. 2291-2296 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Stress development in thin layers of lead titanate prepared by sol-gel processing was monitored by in situ laser reflectance measurements. Layers were spin coated onto silicon substrates and thermally cycled to 500 °C. The shrinkage normal to the rigid substrate was determined by in situ ellipsometry. Changes that occurred on drying and firing, which related to densification and stress development, are reported. The observed changes were explained in terms of evaporation and solvent/polymeric network interactions at lower temperatures, and thermal expansion mismatch between the substrate and the coating after formation of the dense oxide. Crystallization into the perovskite structure occurred only in thicker or multideposited coatings, altering the state of stress from tensile, to progressively more compressive, on cooling. The importance of the choice of substrate material, deposition method and heat treatment conditions, in relation to stress development and dependent electrical properties, are discussed. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.366971
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  • 8
    Electronic Resource
    Electronic Resource
    A mesogenic alkenyl compound (1999)
    Oxford [u.a.] : International Union of Crystallography (IUCr)
    Acta crystallographica 55 (1999), S. 403-405 
    Details
    ISSN: 1600-5759
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0108270198013791
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  • 9
    Electronic Resource
    Electronic Resource
    Analgesic efficacy and pharmacokinetics of topical nimesulide gel in healthy human volunteers: double-blind comparison with piroxicam, diclofenac and placebo (1998)
    Springer
    European journal of clinical pharmacology 54 (1998), S. 541-547 
    Details
    ISSN: 1432-1041
    Keywords: Key words Nimesulide ; Topical gel ; Analgesia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract Objective: The present study was conducted to compare the analgesic efficacy of a new topical gel formulation of nimesulide (10 mg of pure drug) with that of placebo, diclofenac and piroxicam gels (10 mg of pure drug) in three parallel groups in a double-blinded, randomized fashion with vehicle placebo. The analgesic activity of nimesulide was subsequently correlated with its pharmacokinetic profile. Methods: The drugs were applied on a fixed marked area on the skin of the right forearm. Pain stimulus was administered using a modification of the Hollander method, before and at 15, 30, 60, 120 min and 240 min post-treatment. The pain experienced by the subjects was ranked separately on the visual analogue scale (VAS) and the ten-point category scale. Antinociception induced by the treatments was evaluated through the placebo-related ratings (PRR) and total pain relief (TOTPAR) analysis. The plasma concentration of nimesulide was estimated using high-performance liquid chromatography (HPLC). Results: Nimesulide exhibited better efficacy than diclofenac, piroxicam and placebo. It demonstrated faster onset of action in concordance with earlier studies. Peak analgesic effect was observed at 120 min post-treatment, which correlated with the pharmacokinetic profile of the drug in gel formulation. In this study, diclofenac was found to be superior to piroxicam though both drugs exhibited peak analgesic effect at 60 min post-treatment. In the modified Hollander method, a good correlation was found between the ten point category scale and the VAS, indicating that it may serve as a sensitive and reliable method for the screening of analgesic drugs. Conclusion: The superior analgesic activity of nimesulide (as gel formulation), correlating with its pharmacokinetic profile, indicates that the topical route of administration may be a safe and effective alternative to the presently used oral and rectal routes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002280050510
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  • 10
    Electronic Resource
    Electronic Resource
    Breakthrough advances in low loss, tunable dielectric materials (1999)
    Springer
    Materials research innovations 2 (1999), S. 278-282 
    Details
    ISSN: 1433-075X
    Keywords: Key words Ferroelectrics ; Phased array antenna ; Tunable devices ; Thin films
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract  Low loss, tunable dielectric materials are important for phased array antenna and other device applications. Various composites of barium strontium titanium oxide (BSTO) combined with other nonelectrically active oxide ceramics have been formulated for such uses. The dielectric constant and the loss tangents of these composites have been reduced to enhance the overall impedance matching and thereby lowering the overall insertion loss of the device. The material has been fabricated in bulk ceramic, thick film, and thin film form to address a broad range of frequency applications. The material fabrication methods and the electronic properties of these composites will be discussed in this article.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s100190050098
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