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  • 1
    Electronic Resource
    Electronic Resource
    Kidney ischemia-reperfusion: Modulation of antioxidant defenses (2000)
    Springer
    Molecular and cellular biochemistry 205 (2000), S. 1-11 
    Details
    ISSN: 1573-4919
    Keywords: kidney ; ischemia-reperfusion injury ; free radicals ; reactive oxygen species ; gene expression ; antioxidant enzymes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Reactive oxygen species (ROS; O2-, H2O2, and OH·), normal by-products of cellular metabolic processes, are kept in control by antioxidant enzymes, such as catalase, glutathione peroxidase (GPX) and superoxide dismutases (SODs). To understand the role of antioxidant enzymatic defenses against ROS injury following ischemia-reperfusion, we examined the effect on kidney exposed to varying periods (30, 60 or 90 min) of ischemia followed by different periods of reperfusion. The enzymatic activities and protein levels of catalase, GPX, CuZnSOD and MnSOD were relatively unaffected at 30 min of ischemia followed by 0, 2 or 24 h reperfusion. However, 60 or 90 min of ischemia followed by 0, 2 or 24 h of reperfusion resulted in a decrease in activities and protein levels which paralleled the duration of ischemic injury. MnSOD activity tended to recover towards normal during reperfusion. Examination of the mRNA levels of these antioxidant enzymes demonstrated a severe decrease in mRNA levels of catalase and GPX at a time point of minimal ischemic injury (30 min of ischemia followed by reperfusion) suggesting that loss of mRNA of catalase and GPX may be the first markers of alterations in cellular redox in ischemia-reperfusion injury. Greater loss of mRNA for catalase, GPX and CuZnSOD were observed following longer periods (60 or 90 min) of ischemia. The mRNA for MnSOD was upregulated at all time points of ischemia-reperfusion injury. Actually, the greater decrease in mRNAs for catalase, GPX and CuZnSOD in the acute phase (within 24 h) subsequently showed a further decrease in these enzyme activities in the subacute phase (72 or 120 h after ischemia). These enzyme activities in the 30 min ischemia group, but not in the 90 min group, already showed tendencies for normalization at 120 h after ischemia. To understand the molecular basis of the loss of mRNA of these antioxidant enzymes during ischemia-reperfusion injury, we examined the rate of transcription by nuclear run-on assays. The similar rates of transcription in control and kidney exposed to ischemia-reperfusion indicates that the loss of mRNA for catalase, GPX and CuZnSOD are possibly due to the increased rate of turnover of their mRNAs. These studies suggest that expression of antioxidant genes during ischemia-reperfusion are not coordinately expressed and the differential loss of antioxidant enzymes may be the contributing factor(s) towards the heterogeneous renal tissue damage as a result of ischemia-reperfusion induced oxidative stress.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007047505107
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  • 2
    Electronic Resource
    Electronic Resource
    Edge potential effect on the operation of short-channel devices (2003)
    Bingley : Emerald
    Microelectronics international 20 (2003), S. 23-28 
    Details
    ISSN: 1356-5362
    Source: Emerald Fulltext Archive Database 1994-2005
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: We have solved the two-dimensional Poisson's equation for short-channel device under the assumption that even in the absence of drain-to-source voltage (VDS), a potential occurs at the edges (source/drain) due to discontinuity at the semiconductor - channel interface in addition to built-in-potential. We have developed some new relations governing the operation of short-channel devices. Analysis of relation shows that in the absence of drain-to-source voltage (or for very low drain-to-source voltage), the position of minimum potential will occur exactly at the middle of the channel. The short-channel effect is not only observed due to applied drain-to-source voltage, but also due to edge potential when no bias is applied between drain and source.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1108/13565360310487918
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  • 3
    Electronic Resource
    Electronic Resource
    Corrosion of stainless steels in chlorine dioxide solution (2002)
    Bradford : Emerald
    Anti-corrosion 49 (2002), S. 417-425 
    Details
    ISSN: 0003-5599
    Source: Emerald Fulltext Archive Database 1994-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Until recently, chlorine used to be an important chemical in bleaching process in paper industry, but as a result of environmental concerns, it is being replaced by chlorine dioxide. However, chlorine dioxide is more corrosive in certain conditions. Plant personnel, therefore need to better understand the reactions taking place in the changed media and search for more resistant materials. It is with this in mind that the present work was undertaken. The paper reports the electrochemical polarisation measurements performed on stainless steels 316L, 317L, 2205 and 254SMO in chlorine dioxide solutions to observe localised corrosion. The results have been analysed with reference to Pourbaix diagrams, taking into account the various chemical species present in the bleach solutions. Conclusions drawn from electrochemical tests have been compared with those from long-term laboratory and plant tests. Materials options are proposed on the optimal choice of materials for bleach plants, in a context of probable corrosion performance, capital cost and mechanical strength.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1108/00035590210452761
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  • 4
    Electronic Resource
    Electronic Resource
    Level structure of odd-odd 68Ga (2000)
    Springer
    The European physical journal 9 (2000), S. 197-200 
    Details
    ISSN: 1434-601X
    Keywords: PACS. 27.50.+e 59 ≤A≤ 89 – 23.20.Lv Gamma transitions and level energies – 23.20.En Angular distribution and correlation measurements
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract: Excited states of 68Ga have been investigated through the 55Mn(16O, 2pn) reaction at projectile energy 55 MeV. The level scheme has been extended up to 7.8 MeV. Altogether six new excited levels could be identified and twelve previously unobserved γ-transitions have been placed in the modified level scheme.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s100500070037
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  • 5
    Electronic Resource
    Electronic Resource
    Soil properties under Acacia nilotica trees in a traditional agroforestry system in central India (2000)
    Springer
    Agroforestry systems 49 (2000), S. 53-61 
    Details
    ISSN: 1572-9680
    Keywords: C:N ratio ; C:P ratio ; dispersed trees ; N mineralization ; soil texture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Acacia nilotica (L.) Willd. ex Del is an important multipurpose tree of traditional agroforestry system in the central belt of the Indian sub-continent. The tree is reported to reduce crop yields under its canopy. However, information is lacking on the spatial variation in soil physical characters, nutrient pool sizes and their availability to crops under its canopy. The present study reports influence of three tree canopy positions, viz. mid canopy, canopy edge and canopy gap, of Acacia nilotica (≥ 12 years) on texture, organic C, total and mineral N and P, and soil pH, in 0 to 10, 10 to 20 and 20 to 30 cm depth of the soil at ten sites in a traditional agroforestry system. Sand particles declined by 10% and 9% whereas clay particles increased by 14% and 10% under mid canopy and canopy edge, respectively, compared to that under canopy gap. Clay particles did not decline significantly with soil depth under all canopy positions. Proportion of silt particles was not influenced by the canopy position. Soil organic C, total N, total P, mineral N (NO3 −-N and NH4 +-N) and P were greater under mid canopy and canopy edge positions compared to canopy gap. Soil organic C and N pool sizes were maximum in 0 to 10 cm and declined with the depth of soil. Total and mineral P contents were nearly uniform across the depths. C/N ratio tended to increase with the soil depth whereas C/P ratio declined.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006314411454
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  • 6
    Electronic Resource
    Electronic Resource
    Potentiometric measurement of stability constants of complexes between fulvic acid carboxylate and Fe3+ (2000)
    Springer
    Plant and soil 223 (2000), S. 13-21 
    Details
    ISSN: 1573-5036
    Keywords: Fe3+ complexes ; fulvic acid (FA) ; humic substances ; stability constants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The stability constants of complexes formed between iron (III) and fulvic acid extracted from organic manures and wastes such as urban domestic sewage sludge, farmyard manure, poultry manure and sulfitation pressmud were investigated by the potentiometric titration method in an ionic medium of 0.1 M KNO3 at 25±1 °C. A modification of the Katchalsky's model was employed for the estimation of stability constants. The displacement of the titration curves due to presence of Fe3+ in FA solutions formed the basis of calculations. The weak acidic property of fulvic acids due to carboxyl groups resulted in buffering over a wide range of pH; fulvic acids were completely neutralized in the pH range of 7.00–8.85. Apparent dissociation constants (pKAPP) of weakly acidic carboxyl groups were a direct function of degree of dissociation (αL) in the mid-range of titration curves but were non-linear at high and low αL values. The stability constants for formation of Fe–FA complexes (log βFe) calculated from the titration data were in the range of 5.64–7.55, depending upon αL and electrostatic properties of fulvic acids. The relatively high stability constants of Fe–FA complexes in comparison to those with other competing cations suggest that the Fe–FA complexes are relatively stable in a soil environment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004744529118
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