MHD free convection-radiation interaction in a porous medium - part I : numerical investigation

A numerical investigation of two dimensional steady magnetohydrodynamics heat and mass transfer by laminar free convection from a radiative horizontal circular cylinder in a non-Darcy porous medium is presented by taking into account the Soret/Dufour effects. The boundary layer conservation equations, which are parabolic in nature, are normalized into non-similar form and then solved numerically with the well-tested, efficient, implicit, stable Keller–Box finite-difference scheme. We use simple central difference derivatives and averages at the mid points of net rectangles to get finite difference equations with a second order truncation error. We have conducted a grid sensitivity and time calculation of the solution execution. Numerical results are obtained for the velocity, temperature and concentration distributions, as well as the local skin friction, Nusselt number and Sherwood number for several values of the parameters. The dependency of the thermophysical properties has been discussed on the parameters and shown graphically. The Darcy number accelerates the flow due to a corresponding rise in permeability of the regime and concomitant decrease in Darcian impedance. A comparative study between the previously published and present results in a limiting sense is found in an excellent agreement

The influence of hot melt subcoat and Polymer coat combination on highly water soluble sustained release multiparticulate formulation

The purpose of this study was to develop and optimize oral controlled-release formulations for highly water soluble model drug Venlafaxine hydrochlorid using a combination of hot-melt subcoating s based coating polymerand aqueous polymer coating. Hot melt subcoating was achieved by centrifugal granulator. For the polymer coating, Acrylate-based (Eudragit RS 30D and Eudragit NE 30D), were used. Furthermore polymer coating, the pellets were evaluated with respect to their ability to modulate the in-vitro release of a highly water soluble compound. By using hot melt subcoating, the polymer coating level of pellets was reduced by half to obtain sustained release profile. In this study, the release profile of pellets was found to be optimum at a 4% level of hot melt subcoating and 15 % level of Eudragit® NE30D polymer coating combination, consequently meeting the desired responses. The release profile of the pellets prepared by this technique satisfied the first order plot with (R sq =0.9434) indicating the release of water soluble drug from porous matrices. By means of this hot-melt subcoating and polymer coating combination, sustained-release pellets containing venlafaxine hydrochloride were successfully prepared

Polimerización del n-butil cianoacrilato en presencia de surfactantes: estudio de la influencia de los factores de polimerización sobre propiedades de las partículas, carga de fármacos y evaluación de la cinética de liberación de fármacos

Se sintetizaron nanopartículas de polibutil-cianoacrilato mediante polimerización por emulsión en presencia de unsurfactante no iónico (poloxámero 188), en concentraciones superiores a CMC, y se caracterizaron mediante medicionesde potencial zeta, microscopía electrónica de transmisión y análisis de tamaño. Se estudiaron los efectos defactores de polimerización tales como concentración de monómeros, temperatura de polimerización y concentraciónde surfactante sobre el tamaño de la partícula y su distribución. Al variar la concentración no se apreciarondiferencias significativas en el tamaño medio de las partículas ni en su distribución. A temperaturas de polimerizaciónelevadas se observó un aumento significativo en el tamaño de las partículas y una distribución más extendida, encomparación con los resultados obtenidos a temperaturas bajas y moderadas, lo que se puede atribuir a la deshidratacióndel óxido de propileno y de los bloques de óxido de etileno dentro del surfactante. Las concentraciones desurfactante en el rango del estudio no mostraron una influencia apreciable en el tamaño y el patrón de distribuciónde las nanopartículas. La carga de fármacos en las nanopartículas mediante la técnica de incorporación dio comoresultado un mayor grado de captura que la técnica de la adsorción. Sin embargo, las nanopartículas cargadas confármaco mediante la técnica de adsorción presentaron un mayor grado de liberación de clorhidrato de doxorubicinatanto en 0,001N HCl como en solución salina al 0,9 %. Los resultados del análisis cinético revelaron que lasnanopartículas seguían la ecuación de Higuchi, lo que indica la posibilidad de penetración del fármaco en la matrizporosa de las nanopartículas tras la adsorción del mismo

MHD free convection-radiation interaction in a porous medium - part II : Soret/Dufour effects

This paper is focused on the study of two dimensional steady magnetohydrodynamics heat and mass transfer by laminar free convection from a radiative horizontal circular cylinder in a nonDarcy porous medium by taking account the Soret/Dufour effects. The boundary layer equations, which are parabolic in nature, are normalized into non-similar form and then solved numerically with the well-tested, efficient, implicit, stable Keller–Box finite-difference scheme. Numerical results obtained for the velocity, temperature and concentration distributions, as well as the local skin friction, Nusselt number and Sherwood number for several values of the parameters, namely the buoyancy ratio parameter, Prandtl number, Forchheimer number, magnetohydrodynamic body force parameter, Soret and Dufour numbers. The dependency of the thermophysical properties has been discussed on the parameters and showed graphically. Increasing Forchheimer inertial drag parameter reduces velocity but elevates temperature and concentration. Increasing Soret number and simultaneously reducing Dufour number greatly boosts the local heat transfer rate at the cylinder surface. A comparative study between the previous published and present results in a limiting sense is found in an excellent agreement

Preparación y caracterización físicoquímica de una microemulsión de macrogol -8- glicéridos de caprilocaproilo para la administración oral de fármacos

The performance of caprylocapryl macrogol -8- glycerides in the development of pharmaceutically acceptable, stable, selfemulsifyingmicroemulsion was assessed. The suitability of the concentration of surfactant with respect to the oil phasewas assessed by interfacial tension measurement. A pseudoternary microemulsion system was constructed using caprylocaprylmacrogol -8- glycerides / polyglyceryl 6-dioleate / medium chain triglycerides and water. The model microemulsion wascharacterised with regard to its electroconductive behaviour and droplet size measurement after dilution with water aswell as with simulated gastric fluid, surface charge, centrifugal stability, viscosity and stability studies. The percolationtransition theory, which makes it possible to determine the percolation threshold and to identify the bicontinuousstructures, was applied to the system. The interfacial tension changes associated with the microemulsion formation showsultra low values upto 30% oil at a surfactant / cosurfactant ratio 4:1. Moreover, the investigated particle size after dilutionwith excess of water as well as with simulated gastric fluid proved the efficiency of the microemulsion system as a potentialcarrier for oral drug delivery.Se evaluó el rendimiento de los macrogol -8- glicéridos de caprilocaproilo en el desarrollo de una microemulsiónautoemulsionante, estable y aceptable desde el punto de vista farmacológico. Se evaluó la idoneidad de la concentraciónde surfactante en relación con la fase oleosa a través de la medición de la tensión interfacial. Se elaboró unsistema de microemulsiones pseudoternario con macrogol -8- glicéridos de caprilocaproilo/poligliceril 6-dioleato/triglicéridos de cadena media y agua. La microemulsión modelo se caracterizó en relación con su comportamientoelectroconductivo y la medición del tamaño de las gotitas tras su dilución en agua y fluido gástrico simulado, y serealizaron estudios de carga de superficie, estabilidad centrífuga, viscosidad y estabilidad. Se aplicó la teoría de latransición de percolación al sistema, lo que hizo posible la determinación del umbral de percolación y la identificaciónde las estructuras bicontinuas. Los cambios de tensión interfacial asociados a la formación de las microemulsionesmostraron valores muy bajos, hasta un 30% de aceite en una proporción 4:1 de surfactante/cosurfactante. Además,el tamaño de las partículas investigadas tras la dilución en agua abundante y en fluido gástrico simulado demostraronla eficacia del sistema de microemulsiones como un posible sistema de transporte para la administración oral defármacos

Blood flow mediated hybrid nanoparticles in human arterial system : recent research, development and applications

Blood flow dynamics contributes an elemental part in the formation and expansion of cardiovascular diseases in human body. Computational simulation of blood flow in the human arterial system has been widely used in recent decades for better understanding the symptomatic spectrum of various diseases, in order to improve already existing or develop new therapeutic techniques. The characteristics of the blood flow in an artery can be changed significantly by arterial diseases, such as aneurysms and stenoses. The progress of atherosclerosis or stenosis in a blood vessel is quite common which may be caused due to the addition of lipids in the arterial wall. Nanofluid is a colloidal mixture of nanometer sized (which ranges from 10-100m) metallic and non-metallic particles in conventional fluid (such as water, oil). The delivery of nanoparticles is an interesting and growing field in the development of diagnostics and remedies for blood flow complications. An enhancement of nano-drug delivery performance in biological systems, nanoparticles properties such as size, shape and surface characteristics can be regulated. Nanoparticle offers remarkably advantages over the traditional drug delivery in terms of high specificity, high stability, high drug carrying capacity, ability for controlled release. Highly dependency has been found for their behavior under blood flow while checking for their ability to target and penetrate tissues from the blood. In the field of nano-medicine, organic (including polymeric micelles and vesicles, liposomes) and inorganic (gold and mesoporous silica, copper) nanoparticles have been broadly studied as particular carriers because as drug delivery systems they delivered a surprising achievement as a result of their biocompatibility with tissue and cells, their subcellular size, decreased toxicity and sustained release properties. For the extension of nanofluids research, the researchers have also tried to use hybrid nanofluid recently, which is synthesized by suspending dissimilar nanoparticles either in mixture or composite form. The main idea behind using the hybrid nanofluid is to further improve the heat transfer and pressure drop characteristics. Nanoparticles are helpful as drug carriers to minimize the effects of resistance impedance to blood flow or coagulation factors due to stenosis. Discussed various robust approaches have been employed for the nanoparticle transport through blood in arterial system. The main objective of the paper is to provide a comprehensive review of computational simulations of blood flow containing hybrid-nanoparticles as drug carriers in the arterial system of the human body. The recent developments and analysis of convective flow of particle-fluid suspension models for the axi-symmetric arterial bodies in hemodynamics are summarized. Detailed existing mathematical models for simulating blood flow with nanoparticles in stenotic regions are reviewed. The review focuses on selected numerical simulations of physiological convective flows under various stenosis approximations and computation of the temperature, velocity, resistance impedance to flow, wall shear stress and the pressure gradient with the corresponding boundary conditions. The current review also highlights that the drug carrier nanoparticles are efficient mechanisms for reducing hemodynamics of stenosis and could be helpful for other biomedical applications. The review considers flows through various stenoses and the significances of numerical fluid mechanics in clinical medicine. The review examines nano-drug delivery systems, nanoparticles and describes recent computational simulations of nanopharmacodynamics

A review on recent advancements in the hemodynamics of nano-drug delivery systems

Cardiovascular disease (CVD) is a leading cause of mortality and morbidity in developed countries. CVD is produced by atherosclerotic lesions that reduce arterial lumen size through plaque formation and arterial thickening. This decreases blood flow to the heart and frequently manifests in severe hemodynamic complications like myocardial infarction or angina pectoris. A drug delivery system (DDS) is a clinical methodology (formulation or device) which enables the introduction of a therapeutic substance into the body and improves its efficacy and safety by controlling the rate, time, and place of release of drugs in the body. Drug delivery technologies modify drug release profile, absorption, distribution and elimination for the benefit of improving product effectiveness and patient convenience and compliance. The review explores extensively hemodynamic aspects of the cardiovascular system and diseases which can be treated via nanodrug delivery with a comprehensive overview of research efforts in these areas. Nanomedicine is an expeditiously growing science in which biomaterials (drugs) engineered at the nanoscale are implemented to enhance therapeutic performance and improve patient treatments. Among the many other diverse applications of nanomaterials in medicine (e.g. bio-UIRtribology, tissue repair, orthopaedic implants etc), nano-drug delivery systems have emerged as among the most promising. This technology has evolved into a significant platform for delivering successfully remedial agents to diseased sites with substantially greater target control, precision and sophistication. By greatly increasing site specificity, lowering toxicity and target-oriented 2 delivery, nanotechnological drug delivery (“nano-pharmacodynamics”) has consistently achieved very impressive consistency, benefits and has aided massively in the fight against potentially lethal haemotological diseases. Recently, nanomedicine has embraced an even wider range of applications including the administration of chemotherapeutic agents, biological agents, diabetes regulation, sterilization, cancer and tumour inhibition, rheumatic fever mitigation etc. The current review presents a comprehensive appraisal of nano-drug delivery systems, simulation with engineering methods, types of nanodrugs and their effectiveness. The excellent targeting properties attainable with magnetic nanoparticles as engineering pharmacodynamic agents, in particular, offers huge potential in the treatment of many complex hemodynamic disorders. Furthermore, the present review summarizes the efficiency of drug carrier nanoparticles in mitigating the adverse effects of stenosed blood vessels and outlines other future potential uses for nano-drugs in biomedical applications