Highly oxygenated triterpenes from the roots of Atropa acuminata

Two new oleanane triterpenes; 2alpha,3alpha,24-trihydroxyolean-12-ene-28,30-dioic acid ([structure: see text]) and 2alpha,3alpha,24,28-tetrahydroxyolean-12-ene ([structure: see text]) have been isolated from the roots of Atropa acuminata. Anti-oxidant p-hydroxyphenethyl trans-ferulate ([structure: see text]), beta-sitosterol-3-O-beta-D-glucopyranoside ([structure: see text]) and oleanolic acid ([structure: see text]) have also been reported for the first time from this species. The structures were determined by spectroscopic studies including 2D-NMR.     

An expedient esterification of aromatic carboxylic acids using sodium bromate and sodium hydrogen sulfite

Treatment of aromatic carboxylic acids and substituted toluenes with a mixture of sodium bromate and sodium hydrogen sulfite in a two-phase system gave the corresponding esters in good yield. The intermediate α-brominated toluene was formed by the in situ generated hypobromous acid. The α-bromotoluene underwent an intermolecular nucleophilic substitution reaction with aromatic carboxylic acids present in the reaction mixture to afford the corresponding esters.     

Two new isoflavanoids from the rhizomes of Iris soforana

Two new isoflavones 1 and 2 along with eleven known compounds 3-13, have been isolated for the first time from the rhizomes of Iris soforana. The structures of these compounds were determined on the basis of spectroscopic methods and found to be 5,3'-dihydroxy-4'-methoxy-6,7-methylenedioxyisoflavone (1) (Soforanarin A), and 5,7,5'-trimethoxy-6,3',4'-trihydroxyisoflavone (2) (Soforanarin B).     

Neutron induced radiography in the determination of boron in drinking water

Neutron induced radiography has been applied to the determination of boron concentrations in drinking water, collected from natural springs of Reshian and Muzaffarabad areas of Azad Kashmir, Pakistan, using CR-39 etched track detectors. The technique is based upon the simultaneous irradiation with thermal neutrons of a sample of unknown concentration and a standard of known boron concentration, fixed on a track detector. The subsequent counting of alpha and ⁷Li tracks in the detector resulting from the ¹⁰B(n,)⁷Li nuclear reaction is done after chemical etching. Boron concentration in the sample is determined by comparing ⁷Li and alpha-particle track density with that of a standard of known boron concentration. Boron concentrations in drinking water samples from Muzaffarabad and Reshian area of Azad Kashmir have been found to vary from (0.054±0.001) mg/l to (0.250±0.004) mg/l with an average of (0.16±0.002) mg/l. The observed concentration of boron in drinking water has been found to be less than the provisional Maximum Acceptable Concentration level (0.4 mg//l) of WHO. The drinking water from the reported area has been found to be within safe limits as far as boron related health hazards are concerned.This revised version was published online in November 2005 with corrections to the Cover Date.     

Solvent extraction of trivalent lanthanide Pr(III), Ho(III) and Er(III) with N-benzoyl-N-phenylhydroxylamine

Extraction of Pr(III), Ho(III) and Er(III) has been studied in the pH range of 1–10 with N-benzoyl-N-phenylhydroxylamine (BPHA) in benzene. The separation was found to be quantitative in borate media from pH 7 to 10, at an ionic strength of 0.1M (H⁺, BO₃ ^3–). The stoichiometric composition of the complexes under the optimal conditions of shaking time, pH and reagent concentration was formulated using slope analysis and found to be M(BPHA)₃, where M=Pr(III), Ho(III) and Er(III). The effect of various masking agents shows that citrate, ascorbate, EDTA, oxalate, fluoride and phosphate form stable complexes with these rare earths as compared to BPHA. The decontamination factors for different cations with respect to these rare earths under the optimum conditions have been evaluated.     

All-optical 2R-regeneration and continuous wave to pulsed signal wavelength conversion based on fiber nonlinearity

In this paper, we propose a novel all-optical 2R (re-amplification and re-shaping) regenerator based on inducing nonlinear chirp over a continuous wave probe. The regenerator also performs continuous wave to pulsed wavelength conversion. The chirp is induced in a highly nonlinear fiber by the data modulated pulsed signal that is to be regenerated. Offset filtering is employed at the output of the highly nonlinear fiber to extract the frequencies generated as a result of chirping. The regenerator performance has been evaluated with the help of bit-error-rate plots and eye diagrams at different values of optical signal to noise ratios. Apart from re-shaping and re-amplification, inclusion of the regenerator results in better resilience to amplified spontaneous emission noise.     

Flow and heat transfer with prescribed skin friction in a rotating fluid

This paper investigates the rotating flow and heat transfer of a viscous fluid induced by a stretching surface. The nonlinear problem subject to a given skin friction at the boundary is solved. Analytic solution is obtained using homotopy analysis method. The velocity, temperature, and stretching velocity is calculated for different values of the rotation parameter (λ). The obtained results are compared with the well known results of rotating flow induced by a stretching surface by using four sets of boundary conditions. Copyright © 2011 John Wiley & Sons, Ltd.