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A simple instability condition based on Ziegler's continuum principles as applied to large plastic flow is extended to define the deformation processing maps that delineate 'safe' and 'non-safe' hot working conditions. Processing maps were developed utilising the measured flow stress data of nickel based powder metallurgy superalloys in a constitutive equation. The applicability of the processing maps developed has been examined by comparing with the reported microstructural observations of deformed compression specimens. Optimum hot working conditions for the materials are suggested, based on the maximum values of the strain rate sensitivity index. [ABSTRACT FROM AUTHOR]

The present paper examines the possibility of evaluating the elastic constants of specially orthotropic rectangular thin plates from the measured natural frequencies of cantilever plates. An expression is developed for orthotropic rectangular thin cantilever plates to determine natural frequencies, and its validity is demonstrated through finite element analysis as well as using published test results. [ABSTRACT FROM AUTHOR]

An attempt has been made to design suitable liposome and niosome-encapsulated drug delivery system for rifampicin and evaluated the same in vitro and in vivo. A modified lipid layer hydration method was employed to prepare these vesicular carriers. The formulated systems were characterized in vitro for size distribution analysis, drug entrapment, drug release profiles and vesicular stability at different conditions of storage. In vivo drug kinetics was evaluated in normal, healthy albino rats for niosomal formulation upon subcutaneous injection and various pharmacokinetic parameters were determined. Niosomes and liposomes exhibited mean diameter of 9.73 and 11.87 microns with entrapment efficiencies of 30.5 and 34.2% respectively. Both the products exhibited sustained release characteristics in vitro with zero order drug release kinetics up to initial 10 hr. Stability evaluation indicated that both formulations were not significantly leaky over a period of one month. Niosomal formulation elevated plasma elimination half life and decreased elimination rate constants for rifampicin in vivo suggested that encapsulation retarded the removal of the drug from circulation compared to free drug due to slow drug release into systemic circulation. A five-fold increase in the area under plasma rifampicin concentration-time curve for niosomal rifampicin as compared to free drug indicated better bioavailability of encapsulated drug. It is evident from this study that niosomes and liposomes could be promising delivery systems for rifampicin with prolonged drug release profiles and reasonably good stability characteristics.