Friedel–Crafts catalysis using supported reagents. Synthesis, characterization and catalytic application of ZnCl2 supported on fluoride‐modified sol–gel‐derived aluminosilicates

ZnCl₂–aluminosilicate catalysts were prepared via a sol–gel route involving fluoride‐catalyzed hydrolysis of aluminum and silicon alkoxides in the presence of NaF, KF, NH₄F and ZnF₂. The catalysts were characterized by employing ²⁹Si, ²⁷Al and ¹⁹F solid‐state MAS NMR. The dependence of the activities of the catalysts on the nature and amount of fluoride present in the catalysts were investigated using Friedel–Crafts alkylation reaction of benzene with benzyl chloride. This revised version was published online in July 2006 with corrections to the Cover Date.     

Transesterification of β ‐keto esters catalysed by transition metal complexes in a novel heterogeneous way

β‐keto esters have been successfully transesterified with primary, secondary, tertiary, allyl and alkynic alcohols by recyclable Mn(III) salen or vanadyl(IV) acetate catalysts realised while conducting the reaction deliberately for the first time in a novel heterogeneous media to afford good to excellent yields. This revised version was published online in July 2006 with corrections to the Cover Date.     

Convenient synthesis of (thiocyanomethyl)-thio heteroaromatics as antifungal agents

Synthesis of some (thiocyanomethyl)-thio heteroaromatic derivatives by reacting metal salts of (mercapto) heteraromatics with chloromethylthiocyanate using methanol or acetone as cosolvent, reported. All the synthesized derivatives were identified by conventional methods, IR-, ¹H NMR and mass spectral data. All the prepared compounds were tested for their antifungal activity. © 1998 SCI     

Chemical characterisation of CTC black tea of northeast India: correlation of quality parameters with tea tasters' evaluation

BACKGROUND: Consumers have different regional perceptions of tea quality. Objective evaluation based on biochemical data for different regions has been needed for a long time. Biochemical factors regulating this variation would help to remove regional disparities. This study was undertaken on CTC (crust, tear and curl) black tea to generate the biochemical data responsible for quality along with tea tasters' evaluation of three geographical regions of northeast India and to determine the reason for the variation. RESULTS: Brahmaputra valley teas had highest theaflavin (TF), thearubigin (TR), brightness (BR) and total colour (TC) and low crude fibre content (CFC) and total polyphenol (TPP). Brahmaputra valley and Dooars region teas showed high total soluble solid (TSS). Barak valley teas had highest CFC and low TSS, caffeine (CA), TF, TR and TC. Dooars region teas had high CA and TPP and low BR. Dooars region and Barak valley teas contained higher levels of residual catechin than Brahmaputra valley teas. CONCLUSION: Overall quality as evaluated by tea tasters was found to be highest for Brahmaputra valley teas followed by Dooars region and Barak valley teas. This high evaluation can be attributed to higher levels of TF, TR, BR and TSS. Barak valley and Dooars region teas contained high residual catechin, indicating limitation in oxidation during processing. Copyright © 2009 Society of Chemical Industry     

Effect of soya protein on the dialysability of exogenous iron and zinc

The investigation aimed at studying the influence of soya proteins on in vitro dialysability of exogenous iron and zinc. Soyabean was processed into various components like soya flour (SF), concentrate (SC) and isolate (SI) and two peptides (<30 kDa and >30 kDa). The protein contents of SF, SC and SI were 51, 62 and 78 g/100 g, respectively. Their iron contents ranged between 9.7 and 15.8 mg/100 g and zinc contents from 3.3 to 6.7 mg/100 g. Phytic acid contents (mg/100 g) of the soya components were SF 339, SC 226, SI 186 and peptides 18–20. In SF, percent dialysable iron and zinc were 12.6 and 50, respectively, this reduced to one-third and one-fifth in SC and SI. Dialysability of exogenously added minerals was found to be significantly lower in all soya protein components. However, the inhibitory effect was less pronounced in peptides. The protein component/matrix effect needs to be investigated to counteract the inhibitory effect of soya on iron dialysability.     

Polymeric nanofibers as novel carriers for the delivery of therapeutic molecules

Nanotechnology and nanoscience are relatively new technological endeavors that encompass the study, control, manipulation, and assembly of multifarious nanoscale components into materials, systems and devices to serve human interest and needs. Among the various currently used nanostructures for high technology applications polymeric nanofibers have received immense interest due to the ease of fabrication, controllable size/shape, and properties. Polymeric nanofibers have been extensively investigated for diversified applications, including filtration, barrier fabrics, wipes, personal care, biomedical, and pharmaceutical applications. This review mainly focuses on the fabrication of therapeutic agent loaded polymeric nanofibers and their controlled/sustained release behavior for the delivery of these active agents for various therapeutic applications. The nonwoven biodegradable polymeric nanofiber matrices are currently being reported as topical/local therapeutic agent delivery systems and as resorbable/biodegradable gauze for wound healing applications.     

Dielectric properties of DC reactive magnetron sputtered Al2O3 thin films

Alumina (Al₂O₃) thin films were sputter deposited over well-cleaned glass and Si < 100 > substrates by DC reactive magnetron sputtering under various oxygen gas pressures and sputtering powers. The composition of the films was analyzed by X-ray photoelectron spectroscopy and an optimal O/Al atomic ratio of 1.59 was obtained at a reactive gas pressure of 0.03 Pa and sputtering power of 70 W. X-ray diffraction results revealed that the films were amorphous until 550 °C. The surface morphology of the films was studied using scanning electron microscopy and the as-deposited films were found to be smooth. The topography of the as-deposited and annealed films was analyzed by atomic force microscopy and a progressive increase in the rms roughness of the films from 3.2 nm to 4.53 nm was also observed with increase in the annealing temperature. Al-Al₂O₃-Al thin film capacitors were then fabricated on glass substrates to study the effect of temperature and frequency on the dielectric property of the films. Temperature coefficient of capacitance, AC conductivity and activation energy were determined and the results are discussed.