Kinetic analysis of gluconic acid production by Pseudomonas ovalis

A simple growth model is proposed on the basis of the reaction scheme for the conversion of glucose to gluconic acid. The model considers the combined effects of both glucose and oxygen substrates. Kinetic analysis of the system has been made. Computer solution of the equations proposed are obtained and the adequacy of the models confirmed.     

Adaptive relay co-ordination using a busbar splitting approach for a system integrity protection scheme

Power system faults can often result in excessively high currents. If sustained for a long time, such high currents can damage system equipment. Thus, it is desirable to operate the relays in the minimum possible time. In this paper, a busbar splitting approach is used for adaptive relay setting and co-ordination purposes for a system integrity protection scheme (SIPS). Whenever a fault occurs, the busbar splitting scheme splits a bus to convert a loop into a radial structure. The splitting schemes are chosen such that the net fault current is also reduced. Busbar splitting eliminates the dependency upon minimum breakpoints set (MBPS) and reduces the relay operating time, thus making it adaptive. The proposed methodology is incorporated into the IEEE 14-bus and IEEE 30-bus systems with single and multiple fault conditions. The modeling and simulation carried out in ETAP, and the results of the proposed busbar splitting-based relay co-ordination are compared with the MBPS splitting-based relay co-ordination.     

The effect of temperature and moisture on the rheology of black coal-oil suspensions

Rheological properties of black coal-KC220 oil suspensions have been investigated using a Contraves rheometer over a temperature and coal volume fraction range of 18–200°C and 0.247-0.385, respectively. The suspensions behaved as Newtonian fluids. Variation of viscosity with temperature does not follow any regular trend and peak viscosity values occur in the temperature range of 80–140°C for dry coal and 70–130°C for moist coal, depending upon the concentrations of coal in the suspension. Freshly prepared suspensions of moist coal exhibit viscosity peaks at a temperature lower than that of the corresponding suspension with dry coal. However, when aged, the suspensions of moist coal exhibit very small peak viscosity and follow an Arrhenius type behavior. For both dry and moist coal, the maximum volume fraction, ?_m, continues to decrease with an increase in temperature.     

Oxidation of oleanolic acid ofAvicennia officinalis leaves to oleanonic acid in the natural environment of Sunderban mangrove ecosystem

Oleanolic acid, a major component pentacyclic triterpene in the leaves ofAvicennia officinalis was found to be oxidized to oleanonic acid in the natural environment of Sunderban mangrove forest.Presented in part at the All India Symposium on Marine Plants, held on Oct. 30–Nov. 1,1983 at National Institute of Oceanography Dona Paula, Goa India.     

Strain hardening and instability in biaxially streched sheets

This work is concerned with the origins of the two different patterns of failure limits in biaxially stretched sheets which were recently described in Ref. 1: the brass-type in which the limit strain is insensitive to strain state, and that of ferritic steel in which the limit strain increases as the imposed strain-ratio, ρ = ε₂/ε₁, changes from zero (plane-strain tension) toward unity (balanced biaxial tension). An earlier proposal that different slip modes,i.e. wavy in ferrite vs planar in brass, might have contributed to these failurelimit differences was found not to be valid. There were two parts to the main experimental program: the prestraining of small sheets by proportional loading on different paths betweenρ = 0 andρ = 1, followed by tension testing, and a more direct measurement of strain hardening and instability between ρ ≅ — 1/2 (uniaxial tension) andρ = 0. The principal finding was that the overall hardening rate, essentially as it appeared in the material’s effective stress-strain curve, changed with the loading path. Inα brass it decayed as p was increased from ∼—1/2 to 1; in ferritic steel it increased; and in aluminum it was affected very little. Such changes in hardening rate cause similar changes in the material’s capacity for stable flow. The stable flow, in turn, is the base to which a quasistable-flow increment (whenρ is >0) is added in reaching the observed failure limit. Thus a base ofρ-dependent height can account for the failure-limit patterns. There is still no explanation for the ρ dependence of the hardening rate. AMIT K. GHOSH, formerly Graduate Student, Massachusetts Institute of Technology, Cambridge, Mass. 02139, This paper is based upon a thesis submitted by AMIT K. GHOSH in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology.     

Social conflicts and their remedies in the distribution of canal water: Case study of the Damodar valley irrigation project,India

Lower availability of water in canals has caused damage of control structures, breach of minors and sub‐minors and erection of cross bunds to obtain water for crops. This misappropriation has resulted in inter‐ and intra‐village conflicts in the area of the Damodar Valley Irrigation Project in West Bengal. The conflicts are mostly caste based, as is prevalent in Northern India, and subject to political involvement. In the head reach the conflicts over the distribution of water are solved by the intervention of village‐level institutions with the help of community development blocks and irrigation officials. But in the tail reach the village‐level institutions and government officials have played a very limited role in resolving the conflicts. This article examines the nature and causes of the conflicts and some solutions are suggested.     

Structure and mechanism of action and inhibition of steroid dehydrogenase enzymes involved in hypertension

Members of the NADPH-dependent short chain dehydrogenase/reductase (SDR) family control blood pressure, fertility, and natural and neoplastic growth. Despite the fact that only one amino acid residue is strictly conserved in the 100 known members of the family, all appear to have a dinucleotide-binding Rossmann fold and homologous catalytic residues including the conserved tyrosine. Variation in the binding pocket creates specificity for steroids, prostaglandins, sugars and alcohols. The critically important tyrosine appears to maintain a fixed position relative to the scaffolding of the Rossmann fold and the cofactor position, while the substrate-binding pocket alters in such a way that the dehydrogenation/reduction reaction site is brought into bonding distance of the tyrosine hydroxyl group. Licorice induces high blood pressure by inhibiting an SDR in the kidney. The crystal structure of the complex of 3alpha,20beta-hydroxysteroid dehydrogenase and carbenoxolone reveals the mechanism of enzyme inhibition by licorice. The most potent dehydrogenase enzyme inhibitors are those that displace substrate and cofactor and form strong hydrogen bonds to one or more amino acid residues involved in catalysis.