Singular problems on the infinite interval modelling phenomena in draining flows

Existence results are presented for singular boundary-valueproblems on the infinite interval. In particular our theoryincludes a discussion of a problem which arises in the theoryof draining flows. Received 10 February 2001.     

Singular initial and boundary value problems with sign changing nonlinearities

A variety of new existence results are presented for both singularinitial and boundary value problems where the nonlinearity is allowed to change sign. Our theory is then applied to anexample which arises naturally in nonlinear mechanics (thatis, in the membrane response of a spherical cap). Received 17 May, 1999.     

Generation of zonal magnetic fields by drift waves in a current carrying nonuniform magnetoplasma

It is shown that zonal magnetic fields (ZMFs) can be nonlinearly excited by incoherent drift waves (DWs) in a current carrying nonuniform magnetoplasma. The dynamics of incoherent DWs in the presence of ZMFs is governed by a wave-kinetic equation. The governing equation for ZMFs in the presence of nonlinear advection force of the DWs is obtained from the parallel component of the electron momentum equation and the Faraday law. Standard techniques are used to derive a nonlinear dispersion relation, which depicts instability via which ZMFs are excited in plasmas. ZMFs may inhibit the turbulent cross-field particle and energy transport in a nonuniform magnetoplasma.     

Chemo-enzymatic synthesis of both enantiomers of rugulactone

The synthesis of both the (R)- and (S)-enantiomers of the natural product rugulactone has been achieved. Candida rugosa lipase hydrolyzes the butyrate ester of the protected 3-hydroxy homoallylic alcohol with very high enantioselectivity (E = 244) and provides the key intermediates with high enantiomeric purity (ee 98–99%) and excellent yields.     

Asymmetric synthesis of Goniothalesdiol A from (R)-2,3-O-cyclohexylidine glyceraldehyde

Goniothalesdiol A 1 has been synthesized from (R)-2,3-O-cyclohexylidine glyceraldehyde with high stereoselectivity and 22% overall yield in 11 simple steps. The key features of the synthetic strategy include the stereocontrolled allylation of (R)-2,3-O-cyclohexylidine glyceraldehydes; the cross-metathesis with a Grubbs’s second generation catalyst, and the intramolecular base-catalyzed oxy-Michael addition for the formation of the tetrahydropyran ring.     

Scope for Exploitation of Consumers Through Speculation: A Dynamic- Programming Approach to the Case of the Indian Sugar Industry

The Government of India (G.O.I.) controls the quantity of sugar released into the domestic market on a monthly basis. This forms a part of the package of public policies affecting the development of the Indian sugar industry, which includes protection from foreign competition, simultaneous existence of an open market for sugar and distribution of sugar at subsidized prices to consumers through the public distribution system (P.D.S.), minimum support prices for the farmers producing sugar-cane, and differential prices paid to sugar factories for the sugar taken over by G.O.I. for the P.D.S.Using a dynamic-programming approach, this paper describes a worst case analysis of the scope for the traders to exploit the consumers under the current policy of controls over releases into the domestic market. The results show the marginal importance of such controls in saving the consumers from the exploitation by traders. Secondly, on the basis of wider research done by the authors, it is concluded that the scope provided to the traders for the exploitation of consumers through the other policies of the package is of such a magnitude as to make the controls over the releases into the market a relatively insignificant policy intervention for protecting the consumers.     

Laser induced optoacoustic spectroscopy of benzil: Evaluation of structural volume change upon photoisomerization

The cis-skew to trans-planar photoisomerization of benzil in the photoexcited state was studied by laser-induced optoacoustic spectroscopy (LIOAS) in a series of normal alkane solvents at room temperature. The structural volume change due to the photoisomerization process has been estimated and compared with the same calculated from the optimized skew and trans structures. The magnitude of the structural volume change is estimated to be 22.9 ± 1.2 mL/mol. This study reveals that an expansion in volume occurs during the photoinduced isomerization process. In non-polar alkane solvents, the estimated volume change has been argued to be free from electrostrictional contribution.     

LC–UV Assay for Simultaneous Estimation of Aromatic Turmerone, α/β-Turmerone and Curlone: Major Bisabolane Sesquiterpenes of Turmeric Oil in Rabbit Plasma for Application to Pharmacokinetic Studies

The herbal medicament derived from the lipid soluble fraction obtained from Curcuma longa L. (Zingiberaceae) has shown potential neuroprotective activity in disorders like stroke. HM has been standardized with three biomarkers: ar-turmerone, α/β-turmerone and curlone, major bisabolane sesquiterpenes of turmeric oil. Development of a biaonalytical method for these sesquiterpenes was initiated to characterize its preclinical pharmacokinetics in rabbits to accelerate its development as a potential candidate for vascular complications. Since, the compounds are structurally and chemically very similar, gradient elution was utilized on a C-18 reversed phase column with a mobile phase comprising of acetonitrile and deionised water. The UV detector was set at wavelengths 240 and 270 nm. The sample clean-up was performed by protein precipitation with acetonitrile. The method was reasonably sensitive with limits of quantitation (LOQ) of 0.098 μg mL^?1 in plasma for all the analytes. Accuracy and precision were within the acceptable limits, as indicated by relative standard deviation (% RSD) varying from 1.3 to 13.6% and bias values ranging from ?5.5 to 10.3%, respectively. Moreover, the analytes were stable in plasma even after three freeze-thaw cycles. The method was applied to generate preliminary pharmacokinetics of turmeric oil in rabbits after intravenous administration.