The aim of present work was to develop a metformin hydrochloride sustained release tablet by aqueous coating. Eudragit RL and Eudragit RS were used for coating of tablets. Eudragit RL having 10% and Eudragit RS having 5% of functional quaternary ammonium groups, which give rise to pH independent permeability of the polymer. Metformin hydrochloride uncoated tablets were prepared by wet granulation technique. Tablets were coated with blends of Eudragit RS30D and Eudragit RL30D in 5:1 and in 3:1 ratios at different coating level viz. 7%, 5%, 3%, 1.5%, 1%. Two dissolution media: pH 1.2 and pH 6.8 phosphate buffer were employed for in vitro release behaviors of metformin hydrochloride tablets. Coating with blends of Eudragit RS 30D and Eudragit RL 30D in 5:1 and in 3:1 ratio at 1% and at 3% showed sustained release effect for 12 h. The two Eudragit polymers with different features as coating materials produced the desired results.

The refrigeration systems are used in domestic and commercial freezing applications. These systems are needed to be used energy efficiently to get the economic operation condition. The vapor compression refrigeration cycle (VCR) is getting replaced by vapor absorption refrigeration system (VARS) as they can use low grade energy. This VARS can be used by making use of waste energy in the form of heat which is readily available for many applications. Performance of the VARS is dependent on the generator and absorber performance. In absorber it is based on the amount of refrigerant absorbed and the solution flow rate. Experimental and Numerical study of bubble absorber and effect of nanoparticle on ammonia water mass transfer is carried out. In this study, different designs for the absorber chamber are viewed and compared together, based on the research did earlier. Looking at the aspects of bubble type absorber designs, these designs give better mass transfer performance as compared to other designs. These designs may be improved to get the energy efficient design of the absorber. Present study includes the enhancement of mass transfer rate by the addition of nanoparticles using aluminum oxide (Al2O3). Here, sparged vessels with NH3-H2O binary fluid are arranged with varying percentage of nanoparticle (Al2O3). This study includes the study of mass transfer enhancements by using nanoparticles. Based on the experimental results carried out for the varying mass flow rates it is found that the mass transfer rate is enhanced significantly, it is because the interfacial area is enhanced by the addition of nanoparticles to the base fluids.

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