CONTROLLED-POROSITY OSMOTIC PUMP TABLETS-AN OVERVIEW

Conventional drug delivery systems have little control over their drug release and almost no control over the effective concentration at the target site. This kind of dosing pattern may result in constantly changing, unpredictable plasma concentrations. Drugs can be delivered in a controlled pattern over a long period of time by the process of osmosis. Osmotic devices are the most promising strategy based systems for controlled drug delivery. They are the most reliable controlled drug delivery systems and could be employed as oral drug delivery systems. The present review is concerned with the study of drug release systems which are tablets coated with walls of controlled porosity. When these systems are exposed to water, low levels of water soluble additive is leached from polymeric material i.e. semipermeable membrane and drug releases in a controlled manner over an extended period of time. Drug delivery from this system is not influenced by the different physiological factors within the gut lumen and the release characteristics can be predicted easily from the known properties of the drug and the dosage form. In this paper, various types of osmotically controlled drug delivery systems and the basic components of controlled porosity osmotic pump tablets have been discussed briefly

Speciation of L-aspartic acid complexes of Co(II), Ni(II), Cu(II) and Zn(II) in acetonitrile- and ethylene glycol-water mixtures

Chemical speciation of binary complexes of Co(II), Ni(II), Cu(II) and Zn(II) with L-aspartic acid was investigated pH-metrically in acetonitrile- and ethylene glycol-water mixtures. The stability constants were calculated using the computer program MINIQUAD75. The best-fit chemical models were selected based on statistical parameters and residual analysis. The models for the binary species contained ML2H2, ML2H and ML2 for Co(II) and Zn(II), ML, ML2H2 and ML2 for Ni(II) and Cu(II) in acetonitrile- and ethylene glycol-water mixtures. The trend in variation of stability constants with change in the dielectric constant of the medium was explained on the basis of electrostatic and non-electrostatic forces. Distribution of the species with pH at different variations (0.0-60.0% v/v) in acetonitrile- and ethylene glycol-water mixtures was also presented. KEY WORDS: Complex equilibria, L-Aspartic acid, Acetonitrile, Ethylene glycol, MINIQUAD75 Bull. Chem. Soc. Ethiop. 2012, 26(2), 239-247.DOI: http://dx.doi.org/10.4314/bcse.v26i2.

Effect of Troposphere and Ionosphere on C-Band Radar Track Data and Correction of Tracking Parameters

At any launch base radar tracking is critical for assessing the state of the launch vehicle for range safety function as well as for trajectory monitoring. Tracking data corrected for refraction effects is essential for estimating the flight performance. This paper presents the refraction effects of troposphere and ionosphere on the radio waves of C-Band radars in terms of errors in the measured tracking parameters. Application of mapping functions for correcting refraction errors in C-Band radar track data is studied and a comparison of the performance of mapping functions is presented. The mapping functions not only show good convergence at low elevations but also correct around 90 per cent of the refraction error in elevation.Defence Science Journal, 2012, 62(6), pp.420-426, DOI:http://dx.doi.org/10.14429/dsj.62.116

Effect of errors on miss distance of missile trackers in active decoy environment

Lock on missiles are a major threat to vital installations. Soft kill solutions against lock on incoming missiles such as deployment of active decoys can be very effective to war of threat. The weaknesses in onboard missile tracking radars can be gainfully used to increase the miss distance between target and the missile. The effect of geometrical positioning errors of two horn monopulse missile mounted radars has been analyzed in this paper. As so gain differences between the two horns can cause variations in the miss distance. This aspect has also been studied. The variation of miss distance with jammer power to signal ratio (J/S) is also presented. It can be seen that the miss distance is always midway between the target and the decoy. Random angular positioning errors of the missile radar have been analyzed and it is found that the miss distance increases with increase of angular errors

Simulative Analysis with QRED to Decrease Packet Loss

Communication networks are facing packet loss at routers, where different approaches are used to reduce. Similarly RED is one of them, that existing RED [1] [2] algorithm and its variants are found in flow controlling. For minimizing dropping of packets and reducing buffer overflow. This paper propose a new routing algorithm in which additional FIFO controlled queue buffer before existing RED algorithm, to increases performance and throughput of the router. It is experimented and improvements in results are shown with help of OMNet++

Synthesis of some 3-(2-substituted sulfanyl-imidazo [2,1-b][1,3,4] thiadiazol-6-yl)-chromen-2-one and its derivatives

454-458A series of 3-(2-substituted sulfanyl-imidazo [2,1-b][1,3,4] thiadiazol-6-yl)-chromen-2-ones (3) have been synthesized from 3-(2-bromo acetyl) chromen-2-ones 1 and 2-amino-5-thio substituted[1,3,4]thiadiazole 2 in anhydrous ethanol. The 7,8-benzo analogs of 3-(2-substituted sulfanyl-imidazo[2,1-b][1,3,4] thiadiazol-6-yl)-chromen-2-ones 5 have been synthesized under similar conditions. All the synthesized compounds have been characteriszed by analytical and spectral data