A Note on Waves Generated at a Liquid Solid Interface

In this note, a liquid layer above a thermoelastic halfspace is considered. The frequency equation for the waves generated at the interface is obtained and a few limiting cases are discussed

Waves Generated at the Interface Between an Elastic and a Thermo Elastic Solid

In the present note, we study the conditions for propagation of interface waves when one of the solids is a thermo-elastic halfspace and the other an elastic halfspace. The propagation of plane waves along the interface is studied and the frequency equation is derived. In view of the complicated form of this equation, two limiting cases corresponding to very high or very low frequencies are studied. It is also shown that when the coupling constant in the thermo-elastic solid is put equal to zero, the frequency equation reduces to the equation derived by Stoneley. As another particular case, the frequency equations corresponding to very high or very low wave lengths are obtained

Structural, Optical and Magnetic Properties of (In0.90Sn0.05Cu0.05)(2)O-3 Nanoparticles

This study examined structural, optical and magnetic properties of ITO (In0.95Sn0.05)(2)O-3 and Cu doped ITO (In0.90Sn0.05Cu0.05)(2)O-3 nanoparticles synthesized by solid state reaction method. The synthesized nanoparticles were subjected to structural, optical and magnetic studies. The structural properties of the nanoparticles were carried out using XRD, Raman, FT-IR characterization techniques. Optical properties of the samples were studies using UV-Vis-NIR spectrophotometer. The magnetic measurements were carried out using vibrating sample magnetometer. The ITO (In0.95Sn0.05)(2)O-3 nanoparticles exhibited room temperature ferromagnetism with clear hysteresis loop. The strength of magnetization decreased in Cu doped ITO (In0.95Sn0.05)(2)O-3. The ITO nanoparticles were also exhibited ferromagnetism at 100 K with a magnetic moment of 0.02 emu/g

Viscous Liquid Layer Sandwiched Between Two Generalized Thermoelastic Halfspaces

A detailed investigation of waves in a viscous liquid layer of finite thickness sandwiched between two generalized thermoelastic halfspaces reveals the fact that for realistic situations one has to consider the effect of gravity at least in the liquid layer

Note on a Viscoelastic Convection Flow

A mathematical analysis of the free convection flow of an incompressible viscoelastic(Rivlin-Ericksen) fluid from an infinite flat plate under variable suction acted upon by a transverse magnetic field is presented. It is found that the effect of viscoelasticity is to appreciably alter the skin-friction

A Note on waves Generated at a Liquid Solid Interface-II (Viscous Effects)

This paper, being a continuation of a previous note of the same title, deals with the effect of viscosity on the interface waves propagated in a liquid layer overlying a generalized thermoelastic solid halfspace. This note extends the results of Harinath and has applications to defence science and geophysical problems. The problem considered has more relevance to the physical situations encountered in reality than its elastic counterpart. In other words, generalized thermoelasticity fits into the realistic situation better than classical elasticity or coupled thermoelasticity. The details pertaining to the non viscous effects of liquid layer overlying a perfectly elastic halfspace may be found in the treatise by Ewing, Jardetzky and Press those of coupled thermoelasticity in the treatise by Nowacki and details of wave propagation problems in generalized thermoelasticity in the concise paper by Harinath. The stress strain relations used for a viscous fluid may be found in Pipkin, with slight modifications, without any loss in generality. Most of the results obtained here are new

Pharmacological Modulation Of Recombinant Human Two-Pore Domain K+ Channels : Whole-Cell patch-Clamp Analysis

Background potassium currents play an important role in the regulation of the resting membrane potential and excitability of mammalian neurons. Recently cloned two- pore domain potassium channels (K2p) are believed to underlie these currents. The roles of K2P channels in general anesthesia and neuroprotection have been proposed recently. In view of this, we investigated the ability of trichloroethanol (an active metabolite of the non-volatile general anesthetic cldoral hydrate, widely used as a pediatric sedative) to modulate the activity of human TREK-1 and TRAAK channels. We found that trichloroethanol potently activates both hTREK-1 and hTRAAK channels at pharmacologically relevant concentrations. The parent compound chloral hydrate was also found to augtnent the activity of both the channels reversibly. Studies with carboxy- terminal deletion mutants (hTREK-1A89, hTREK-1 A100 and hTREK-1 A1 19), suggested that C-terminal tail is not essential for the activation of TREK-1 by trichloroethanol. Our findings identify TREK-1 and TRCL4K channels as molecular targets for trichloroethanol and we propose that activation of both these channels might contribute to the CNS depressant effects of chloral hydrate. Another channel TASK-2, which is essentially absent in the human brain was also found to be potently activated by both trichloroethanol and chloral hydrate. In another series of experiments, we studied the effects of methyl xanthines caffeine and theophylline on hTREK-1 channels. Caffeine and theophylline are used for therapeutic purposes and frequently cause life-threatening convulsive seizures due to systemic toxicity. The mechanisms for the epileptogenicity of caffeine and theophylline are not clear. Recent experiments using knockout mice provided direct evidence for a role for TREK-1 in the control of epileptogenesis. We hypothesized that the epileptogenicity of caffeine and theophylline may be related to the inhibition of TREK-1 channels. We investigated this possibility and observed massive inhibition of TREK-1 channels at toxicologically relevant concentrations. Experiments with the mutant TREK-1 channel (S348A mutant) suggested the involvement of cANP/PKA pathway in the inhibition of TREK-1 channels by caffeine and theophylline. We suggest that inhibition of TREK-1 channels may contribute to the convulsive seizures induced by toxic levels of caffeine and theophylline. Local anesthetics exhibit their clinical effects not only by binding to voltage-gated sodium channels, but also by interacting with other ion channels such as potassium channels. Because of the physiological significance of TREK-1 channels and their abundant expression in peripheral sensory neurons, we investigated the effects of lidocaine to see whether its interaction with 'REK-1 channels contribute to the conduction blockade. Lidocaine caused dose-dependent inhibition of TREK-1channels and the inhibition was voltage-independent. Cytoplasmic C-terminal tail is critically required for lidocaine action. Inhibition of TREK-1 channels is achieved at concentrations for iiz vivo action and this effect may have implications for the clinically observed drug action of lidocaine

DESIGN AND DEVELOPMENT OF FLOATING PULSATILE DRUG DELIVERY OF LOSARTAN POTASSIUM

Objective: The objective of the present investigation was to the development of floating pulsatile drug delivery system of Losartan potassium (LP) tablets for obtaining no drug release during floating followed by pulsed, rapid drug release to achieve chronotherapeutic release. In hypertension, the risk of getting heart attacks early in the morning is high and therefore, there was need to develop drug delivery, which will release drugs at morning hours and provide efficacious therapy. LP is a short biological half-life (1.5-2.5h) and readily absorbed from the stomach and upper gastrointestinal tract. Methods: Tablet formulation was prepared by press coating of rapid release core tablets and core tablets were further top coated with a buoyant layer of HPMC K4M and sodium bicarbonate. Various grades of HPMC polymer (E5/E15/E50) were used for the pulsatile coating layer. The developed formulations were characterized for physical characteristics, floating lag time, floating time, release lag time, drug content, swelling index, in vitro dissolution studies, DSC and XRD. Results: The FTIR and DSC studies predicted that there was no chemical interaction between drug and excipients. The core tablet coated with HPMC E50 showed a high swelling index and release the drug 97.60±1.2% at 6h. Buoyant layer with 80 mg HPMC K4M and 25 mg sodium bicarbonate gave satisfactory floating lag time. Conclusion: The system showed an excellent lag phase followed by burst release in the distal small intestine, which gives site and time-specific delivery of LP acting as per chronotherapy for treatment of hypertension

COMPARATIVE IN-VITRO ANTIBACTERIAL AND ANTIFUNGAL ATTRIBUTES OF DIFFERENT SOLVENT EXTRACTS FROM LEAF, BARK, ROOT AND INFLORESCENCE OF MEMECYLON UMBELLATUM BURM.

This paper describes the antibacterial and antifungal activities and Minimum Inhibitory Concentration (MIC) of different solvent (pet. ether, chloroform, ethyl acetate, acetone, methanol and water) extracts of leaves, bark, root and inflorescence of Memecylon umbellatum burm. The percent yields from leaves, bark, root and inflorescence was found to be 0.2062 to 2.836, 0.0601 to 0.5142, 0.050 to 1.425, 0.0210 to 0.717 respectively. Overall, acetone extract produced from the leaves exhibited significantly (P < 0.05) higher antibacterial activity along with superior antifungal activity. MIC for acetone and ethyl acetate extract of leaf was found to be 0.5 mg for the entire organisms compared to 3-15 mg for other extracts. Such study will explore pharmacological activity of the tested parts of Memecylon umbellatum burm especially, the leaves which might be valuable for therapeutic applications

Vacuum foam dried sugar-phosphate amorphous mixtures for stabilization of doxorubicin hydrochloride

The objective of the present study was to stabilize doxorubicin hydrochloride in sugar-phosphate amorphous mixtures at ambient temperature by drying it with vacuum foam drying. Finished products were evaluated for foam characteristic, residual moisture content, reconstitution time, percent drug recovery and drug-excipient interactions. FTIR studies revealed existence of physical interaction of drug with sugar. Light microscopy showed formation of amorphous glass which was supported by the observations of XRPD analyses. The optimized composition in vacuum foam drying was processed by lyophilization and their stability was compared. Storage at ambient temperature for 6 months showed that stability of vacuum foam dried product was better than lyophilized products. The amount of residual moisture affected the stability of drug. The detailed study revealed lactose and sodium dihydrogen phosphate is best suited for stabilization of doxorubicin hydrochloride at room temperature.Colegio de Farmacéuticos de la Provincia de Buenos Aire