Properties of squeeze cast Mg-6Zn-3Cu alloy and its saffil alumina short fibre reinforced composites

In the present work, Mg-Zn-Cu alloy (ZC63) and its saffil alumina short fibre reinforced composites produced using the squeeze casting technique were evaluated for their properties. The unreinforced base alloys and their composites were characterized for their microstructure, hardness, yield strength, impact strength, wear resistance and corrosion resistance. The dependence of the properties of composites was studied as a function of fibre volume fraction. Results showed that the composites exhibited improved hardness, yield strength at elevated temperature and wear resistance in comparison to the monolithic alloy. However, ductility, impact strength and corrosion resistance of the composites were inferior to that of the base alloy. The nature of the base alloy matrix in determining the properties of the composites was discussed based on fractographic analysis.     

Microstructural Features of Flow

Cylindrical specimens of commercial pure titanium have been compressed at strain rates in the range of 0.1 to 100 s^-1 and temperatures in the range of 25 °C to 400 °C. At strain rates of 10 and 100 s^-1, the specimens exhibited adiabatic shear bands. At lower strain rates, the material deformed in an inhomogeneous fashion. These material-related instabilities are examined in the light of the “phenomenological model” and the “dynamic materials mode.” It is found that the regime of adiabatic shear band formation is predicted by the phenomenological model, while the dynamic materials model is able to predict the inhomogeneous deformation zone. The cri- terion based on power partitioning is compctent to predict the variations within the inhomo- geneous deformation zone.     

Response of materials as a function of grinding angle on friction and transfer layer formation

Surface texture influences friction and transfer layer formation during sliding contact. In the present investigation, basic studies were conducted using an inclined pin-on-plate sliding apparatus to understand the effect of grinding mark directionality on the coefficient of friction and transfer layer formation. In the experiments, 080 M40 steel plates were ground to attain different surface roughness with unidirectional grinding marks. Pins consisting of soft materials (pure Al, pure Mg, and Al–4Mg alloy) were then slid against the prepared steel plates. The grinding angle (angle between direction of sliding and grinding marks) was varied between 0° and 90° in the tests. The experiments were conducted under both dry and lubricated conditions in an ambient environment. It was observed that the transfer layer formation and the coefficient of friction depend primarily on the directionality of the plate grinding marks. For the case of pure Mg pins, a stick-slip friction phenomenon was observed for all grinding angles under dry conditions and for grinding angles over 25° under lubricated conditions. In the case of Al pins, the stick-slip phenomenon was observed only under lubricated conditions for angles exceeding 25°. The stick-slip phenomena did not occur in any of the conditions studied with Al–4Mg alloy pins. Based on the results, it was concluded that the magnitudes of the friction and the stick-slip motion amplitude (for Al and Mg pins) were primarily controlled by changes in the level of plowing friction.     

Wireless Aspects of Telehealth

Telehealth is the use of electronic information and communication technology to deliver health and medical information and services over large and small distances. Broadband wireless services available today, along with more powerful and convenient handheld devices, will enable a transformational change in health management and healthcare with the introduction of real-time monitoring and timely responses to a wide array of patient needs. Further, a network of low-cost sensors and wireless systems help in creating constantly vigilant and pervasive monitoring capability at home and at work. This paper addresses recent efforts in this growing field, including standards, system architectures, propagation models, and lower layer protocols for body area networks. The paper also suggests the use of cooperative transmission-based strategies for such wireless topologies.     

Application of moisture activated dry granulation (MADG) process to develop high dose immediate release (IR) formulations

Moisture activated dry granulation (MADG) method was used to develop IR tablets with cohesive, fluffy and high dose drugs. To evaluate this approach, three drugs: metformin hydrochloride, acetaminophen and ferrous ascorbate were selected as model compound along with three binders: maltodextrin DE16, PVP K 12 and HPC. The granules were generated using MADG method and tablets were prepared using rotary tablet press. The granules and tablets were characterized for particle size analysis, flow properties, tablet hardness, friability, moisture content, dissolution study, disintegration time and stability study. All results were found to be within acceptable limits. Development of all formulation tablets were found as best fitted for an immediate release of Metformin hydrochloride, acetaminophen and ferrous ascorbate. MADG delivered a robust manufacturing process for generation of granules with excellent flowability. The tablets prepared using this method were found to show better content uniformity, good compactability and low friability. Use of this approach aids to lower the amount of excipients used to overcome physiochemical limitation of the drug substances and there side effects. Both drying and milling steps in wet granulation were not required for MADG process. MADG became a cost effective process which could lead to reduced total tablet size and also save time.     

Intensification of enzymatic conversion of glucose to lactic acid by reactive extraction

Lactic acid is an important commercial product and extracting this out of aqueous solution is a growing requirement in fermentation-based industries and recovery from waste streams. The design of an amine extraction process requires (i) equilibrium and (ii) kinetic data for the acid-amine (solvent) system used. Equilibria and kinetics for lactic acid extraction by Alamine 336 in octanol as a diluent have been determined and compared with other diluents studied earlier. An approach for extracting the lactic acid by a long-chain tertiary amine, which is in the dispersed phase as a liquid ion exchanger (LIX), is presented. A mathematical model for slurry phase reactor with glucose in the continuous aqueous phase, the amine with a diluent in the dispersed phase and the immobilized enzyme as the solid catalyst, has been developed using equilibrium and kinetic data for reactive extraction. Effects of various parameters affecting the conversion of glucose have been discussed. The model has been solved for batch and semi-batch modes. It has been shown that the semi-batch mode yields approximately five times higher productivity than batch mode.     

Separation of phenylacetic acid using tri-n-butyl phosphate in hexanol: Equilibrium and kinetics

Equilibrium and kinetics studies are required to design the continuous extraction process for the acid-extraction system. In the present study, an attempt has been made to investigate the equilibrium and kinetics parameters for the reactive extraction of phenylacetic acid (PAA) with tri-n-butyl phosphate (TBP) in hexanol. The equilibrium results show that the formation of the (1:1) PAA–TBP complex in the organic phase with an overall equilibrium complexation constant (K_e) was 78.74 and 29.15 m³.kmol^?1 for TBP concentrations of 0.734 and 1.464 kmol.m^?3, respectively. The mass transfer coefficients (k_L) for PAA were found to be in the range of 3.7 × 10^–5–6.2 × 10^–5 m.s^?1. Based on the Hatta number (H_a = 8.48), the reaction was found to be fast chemical reaction (regime 3) with the order of reaction as 0.77 and 0.36 with respect to PAA and TBP, respectively. The rate constant of the reaction was obtained as 0.017 kmol.m^?3.s^?1.