Isolation and identification of impurities in L-696, 229 drug substance

Two low level impurities in 3-[2-(2-benzoxazolyl)ethyl]-5-ethyl-6-methyl-2(1H)-pyridinone drug substance (L-696,229) have been isolated by a combination of preparative HPLC, solid-phase extraction and liquid-liquid extraction. They were identified as 3-[2-(2-benzoxazolyl)ethyl]-5-ethyl-6-(2-phenylethyl)-2(1H)-pyridinone (I) and 6,6'-(2-phenyl-1,3-propanediyl)bis[3-[2-(2-benzoxazolyl)ethyl]-5-ethyl-2(1H)-pyridinone] (II) by mass spectrometry and by their (13)C and (1)H-NMR spectra.     

Simultaneous Double-Color Continuous Wave Raman Fiber Laser at 1239 nm and 1484 nm Using Phosphosilicate Fiber

Simultaneous double-color high-power continuous wave (CW) Raman fiber laser at 1239 nm and 1484 nm is demonstrated which uses CW 8.4 W Yb-doped double-clad fiber laser at 1064 nm as a pump, 1 km phosphosilicate fiber, and cascaded cavities consisting of two pairs of fiber Bragg grating (FBG) mirrors. Maximum output powers are 0.65 W at 1239 nm and 0.97 W at 1484 nm with a 50%/50% output mirror reflectivity pair, and 0.37 W at 1239 nm and 1.06 W at 1484 nm with a 75.5%/50% pair. The output characteristics of this laser for different FBG mirror reflectivities are reported.     

Studies on Trace Labelling of Bromsulphalein (BSP) with Radioiodine

Two methods have been studied for high specific activity trace iodination of Bromsulphalein (BSP) with radioiodine (¹³¹I). In the first method, BSP in aqueous solution is reacted with iodine and an oxidising agent – hydrogen peroxide or chloramine T. In the second method, iodination is carried out by electrolytically liberated iodine. The electrolytic method gives labelled BSP free from any labelled degradation products. The stability of ¹³¹I-labelled BSP in aqueous solution has been studied. The product has been found to remain more stable in aqueous solutions at a slightly acid pH (4…6.5) than in dilute alkaline solutions (pH 7…9.5).     

Self-organisation properties of homomeric dipeptides derived from valine

Three optically active liquid crystal (LC) homomeric dipeptides, in particular, a pair of enantiomers and a diastereomer formed by joining two half-disc-like entities through a dipeptide spacer comprising L-L, D-D and L-D valine residues, have been synthesised and characterised. Hydrogen-bond-directed self-assembly of these non-discoid supramolecules results in the formation columnar (Col) LC phase. They form a stable organo gel in polar organic solvents through intermolecular hydrogen bond, and their scanning electronic microscopy (SEM) images reveal the presence of entangled network. The interaction of these homomeric dipeptides with nanaoparticles (silica species) has also been investigated by SEM images and UV-visible experiments.     

Influence of contact resistance and natural convection effects on non-dimensional effective thermal conductivity estimation of two-phase materials

In this article, the development of geometry dependent resistance model by considering contact resistance and natural convection effects are used to estimate the effective thermal conductivity of two-phase materials based on the unit cell approach. The algebraic equations have been derived based on isotherm approach for 2-D and 3-D spatially periodic medium. Comparison study has been made between developed models and experimental data. The result agrees well with experimental values.     

Distribution of uranium at Mumbai Harbour Bay (MHB)

Mumbai Harbour Bay (MHB) is a recipient of low level treated effluents from BARC, Trombay. In addition, the Bay is also a recipient of domestic and industrial wastes from the city of Mumbai and adjoining areas. The average value of uranium concentration reported for Indian Bay water at Tarapur and Mumbai is ~3.0 ppb which is comparable with the reported value for Arabian sea. As such the global average is reported to be ~3.3 ppb by Oceanologists. The present study deals with the distribution of uranium in seawater of MHB. The uranium activity in MHB by alpha spectrometry was found to be between 1.0 and 4.4 ppb with an average concentration of 2.5 ppb which is comparable with the earlier reported average activity of 2.6 ppb in the MHB as well as those reported globally. To compare the results obtained by alpha spectrometry, uranium estimation was also carried out using Laser fluorimeter and the levels of uranium concentration have ranged between 0.8 and 4.9 ppb with an average concentration of 2.7 ppb.     

Quantitative measurement of the polydispersity in the extent of functionalization of glass‐forming calix[4]resorcinarenes

The polydispersity in the degree of functionalization for two calix[4]resorcinarenes was determined by measuring quantitatively their molecular mass distribution with matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry. A mathematical method for polydisperse materials is described that creates a calibration curve to correct the ion signal intensities in the mass spectrum to give a more reliable molecular mass distribution. Correction is required due to various sample preparation and instrumental effects that may produce a systematic mass bias in the number of oligomers measured. This method employs gravimetric mixtures of analytes with different degrees of functionalization. One calix[4]resorcinarene was found to give accurate molecular mass distributions with little correction, while another, having a very similar molecular structure, was found to exhibit strong over‐counting of the oligomers having a high degree of functionalization. Copyright © 2009 John Wiley & Sons, Ltd.     

6α,7α-epoxy-5α,17α,dihydroxy-1-oxo-22R-witha-2,24-dienolide in leaves of Withania somnifera: Isolation and its crystal structure

6α,7α-epoxy-5α,17α,dihydroxy-1-oxo-22R-witha-2,24-dienolide (C₂₈H₃₈O₆) was isolated from Withania somnifera leaves. The structure of the withanolide was established by spectral analysis and X-ray diffraction studies as withanone. The compound crystallizes in the orthorhombic space group P2₁2₁2₁ with unit cell parameters: a = 9.191(10) Å, b = 12.858(6) Å, c = 21.400(16) Å, Z = 4. The crystal structure was solved by direct methods and refined to R = 0.0603 for 1742 observed reflections. There is positional disorder of the H atom in a hydroxy group (O5), resulting in two possible hydrogen-bond linkages. All the rings of the steroid skeleton are trans connected. Ring A exists in a half-chair conformation, ring B is intermediate between a half-chair and a sofa, ring C a distorted chair, and five-membered ring D is intermediate between a half-chair and an envelope. The δ-lactone ring E adopts a sofa conformation. The twist along the length of the steroid nucleus is negligible [C19–C10…C13–C18=1.8°]. Both the hydroxy groups are involved in hydrogen bonding.     

Highly diastereoselective oxidations of a thioether appended with a neighboring hydroxyl group

Highly diastereoselective oxidations of $\text{endo}$-alcohol $\text{1}$ to the corresponding sulfoxides, the relative stereochemistries of these sulfoxides and that of an intermediary alkoxysulfonium salt determined by X-ray crystallographic analysis is reported.     

Further results for ladder processes in continuous time

The distribution of ladder variables is obtained for the class of processes with stationary independent increments for which they are almost surely positive. This result is used to derive some related distributions. It is proved that a Wiener-Hopf factorization completely analogous to the one for random walks holds if and only if the process is compound Poisson with zero drift.