Liquid Phase Regioselective Bromination of Aromatic Compounds Over Hzsm-5 Catalyst

A simple, efficient, regioselective and environmentally safe method for oxybromination of activated aromatics catalyzed by HZSM-5 is reported. The electrophilic substitution of bromine generated from KBr using HZSM-5 as a catalyst and H₂O₂ as an oxidant.     

Separation of uranium from solid (U,Pu, Ag) oxide analytical waste: effect of batch size and nitric acid molarity

This work presents the investigation of some commercially available and commonly used Si₃N₄ foils prepared with LPCVD technique. The density and the stoichiometry of these films were determined by Rutherford backscattering spectroscopy and profilometry, while the study of impurities was achieved with particle induced X-ray emission method. It was found that the density of the studied Si₃N₄ films is significantly less (~2.71 g cm^?3), while the stoichiometry is close to the values of the bulk material. The results were verified by measuring the ion energy loss through the films by scanning transmission ion microscopy.     

A sharp‐interface immersed boundary framework for simulations of high‐speed inviscid compressible flows

A new finite‐volume flow solver based on the hybrid Cartesian immersed boundary (IB) framework is developed for the solution of high‐speed inviscid compressible flows. The IB method adopts a sharp‐interface approach, wherein the boundary conditions are enforced on the body geometry itself. A key component of the present solver is a novel reconstruction approach, in conjunction with inverse distance weighting, to compute the solutions in the vicinity of the solid‐fluid interface. We show that proposed reconstruction leads to second‐order spatial accuracy while also ensuring that the discrete conservation errors diminish linearly with grid refinement. Investigations of supersonic and hypersonic inviscid flows over different geometries are carried out for an extensive validation of the proposed flow solver. Studies on cylinder lift‐off and shape optimisation in supersonic flows further demonstrate the efficacy of the flow solver for computations with moving and shape‐changing geometries. These studies conclusively highlight the capability of the proposed IB methodology as a promising alternative for robust and accurate computations of compressible fluid flows on nonconformal Cartesian meshes.     

Estimation of Phase and Its Higher Order Derivatives from a Single Complex Interferogram

This paper reports a method for the simultaneous estimation of unwrapped phase and higher order phase derivatives from a single phase fringe pattern recorded in an optical interferometric setup, thereby overcoming substantial barriers to achieving such measurements. The proposed method considers the interference phase as a weighted linear combination of Gaussian radial basis functions defined along a given row or column at a time. The Gaussian radial basis functions are defined with a constant standard deviation and equally spaced centers. Unscented Kalman filter is employed for the accurate estimation of the weights of the basis functions using the state space representation of the spatial evolution of the interferogram. The estimated weights along with the numerically computed gradients of the basis functions also provide the estimations of phase derivatives of arbitrary order. The proposed representation of interference phase along with the unscented Kalman filter provides high robustness against the speckle noise. Simulation study is preformed to evaluate the dependence of the phase and phase derivative estimation accuracy on the selection of basis dimension and the noise level. Experimental results demonstrate the practical applicability of the proposed method.     

The Synthesis and Biological Evaluation of Regioisomeric Benzothiazolyl Coumarins

Various 4-aryloxymethylcoumarins have been obtained by the r.t. allylic substitution with formylphenols. These have been further reacted with o-aminothiophenol resulting in the formation of a benzothiazole skeleton. These compounds have been synthesised with a view to study their potential as microbial growth inhibitors. Comparative studies on the spectral and antimicrobial activities have also been carried out.     

TRANSPORT STUDIES ON MACROMOLECULES USED AS DRUG CARRIERS

Abstract

Modecular transport of drugs through carier polymeric materds has been an active area of research. A number of soluble polymers have been used to deliver the drugs selectively to specific parts of the body. The literature in this area of research is extensive and diverse. An effort has been made to review the transport of drug molecules through physiological systems via polymeric materials. A brief introduction to the fundamentals and concepts which are frequently used in the drug-delivery area are covered in the following sections. Various aspects of the problems related to polymer-drug complexes, carrier molecules, and their degradability have been discussed. Both natural and synthetic biopolymers have been included in the discussion. Only representative references during the period 1977–1989 have been used in the discussion of results, and thus the reader is advised to look further into the original literature for greater information.     

A Preferred Intramolecular ‘Ene’ Reaction Between Ketene and Olefin

Aplysin (1), a marine sesquiterpene was isolated from ‘aplysia kurodai’ and its structure was ellucidated by Hirata-et-al¹. They also reported the synthesis of racemic aplysin². Their synthetic route involved cyclopentanone (2) as a well-characterized intermediate. We visualized the synthesis of cyclobutanone (3) and its subsequent conversion to (2) as an attractive alternative. But during our attempts to synthesize the said cyclobutanone, we have come across a very facile intramolecular ‘ene’ reaction between ketene and olefin. We report our unexpected observations in this communication.     

Selective SN2′ Solvolysis in Borohydride Reduction of 2-Isobutylidene-1-indanone/Tetralone

Selective s_N2′ solvolysis in borohydride reduction of the title compounds is described. As a result, an isomer more stable than the normal reduction product is obtained. Confirmative studies have also been carried out to eliminate the probable acid catalysed rearrangement mechanism.     

Investigation of Diels–Alder Reaction of 7‐Substituted 4‐Styrylcoumarins with Symmetrical Dienophiles Leading to 3,4‐Annulated Coumarins

The thermal [4 + 2] cycloaddition reaction of 7‐substituted 4‐styrylcoumarins with N‐phenylmaleimide and tetracyanoethylene in nitrobenzene under reflux conditions rapidly gives 3,4‐annulated coumarins as the Diels–Alder adducts. The position of the surviving double bond was determined on the basis of NMR and supported by energies of the possible structures. The effects of the 7‐substituent and the solvent on the reaction were studied.