The effect of a soluble surfactant on the linear stability of layered two-phase Poiseuille flows through soft-gel-coated parallel walls is studied in this paper. The focus is on determining the effect of the elastohydrodynamic coupling between the fluids and the soft-gel layers on the various flow instabilities. The fluids are assumed Newtonian and incompressible, while the soft gels are modeled as linear viscoelastic solids. The effect of a soluble surfactant on the different instabilities is specifically investigated. The soft-gel-coated plates are maintained at two different solute concentrations. The dynamics of the soluble surfactant in the fluids is captured using a species transport equation. A linear stability analysis is carried out to identify different instabilities in the system. The linearized governing equations are solved numerically using a Chebyshev spectral Collocation technique. The effect of deformability of the soft gels on three distinct instability modes, (a) a liquid-liquid long-wave mode, (b) a liquid-liquid short-wave mode, and (c) a liquid-liquid Marangoni short-wave mode, is analyzed. An analytical expression for the growth rate is obtained in the long-wave length limit using an asymptotic analysis. From the long-wave analysis a stability map is obtained, in which dominant effects in different regions are identified. The Marangoni stresses can either stabilize or destabilize the interfacial instability depending on the direction of mass transfer. They have a predominantly stabilizing effect on the interfacial instability when the mass transfer is from the more viscous broader fluid to the less viscous thinner fluid. Placing a gel closer to the more viscous fluid has a stabilizing effect on this instability. The Marangoni stresses and soft-gel layers can have opposing effects on the stability of the long-wave mode. The dominant of these two opposing effects is determined by the prevailing parameters. Insights into the dominant physical causes of different instabilities are presented.
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http://dx.doi.org/10.1103/PhysRevE.98.023106 | DOI Listing |
Pharmaceutics
January 2025
Department of Pharmaceutical Sciences, College of Clinical Pharmacy, King Faisal University, Al-Ahsa 31982, Saudi Arabia.
Nanosuspensions (NS), with their submicron particle sizes and unique physicochemical properties, provide a versatile solution for enhancing the administration of medications that are not highly soluble in water or lipids. This review highlights recent advancements, future prospects, and challenges in NS-based drug delivery, particularly for oral, ocular, transdermal, pulmonary, and parenteral routes. The conversion of oral NS into powders, pellets, granules, tablets, and capsules, and their incorporation into film dosage forms to address stability concerns is thoroughly reviewed.
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January 2025
Laboratory of Pharmaceutical Technology and Biopharmacy, Center for Interdisciplinary Research on Medicines (CIRM), University of Liège, 4000 Liège, Belgium.
Cannabidiol (CBD) shows interesting therapeutic properties but has yet to demonstrate its full potential in clinical trials partly due to its low solubility in physiologic media. Two different formulations of CBD (amorphous and lipid-based) have been optimized and enable an increase in bioavailability in piglets. In vivo studies are time-consuming, costly and life-threatening.
View Article and Find Full Text PDFMolecules
January 2025
Laboratoire de Chimie Agro-Industrielle (LCA), Université de Toulouse, INRAE, 4 allée Emile Monso, 31030 Toulouse, France.
In organic synthesis, the solvent is the chemical compound that represents the largest proportion of the process. However, conventional solvents are often toxic and dangerous for the environment, and an interesting alternative is to replace them by water. In this context, catalyst surfactants allow both organic reagents in water to be solubilized and organic reactions to be catalyzed.
View Article and Find Full Text PDFInt J Mol Sci
January 2025
Department of Pharmacognosy and Biomaterials, Faculty of Pharmacy, Poznan University of Medical Sciences, 3 Rokietnicka St., 60-806 Poznan, Poland.
Apigenin (APG), a bioactive flavonoid with promising therapeutic potential, suffers from poor water solubility, which limits its bioavailability. To address this, solid dispersions of APG were prepared using ball milling with sodium alginate (SA), Pluronic F-68 (PLU68), Pluronic F-127 (PLU127), PVP K30, and PVP VA64 as polymeric excipients. These dispersions were screened for apparent solubility in water and buffers with pH 1.
View Article and Find Full Text PDFAntioxidants (Basel)
December 2024
Faculty of Agriculture, Forestry and Food Engineering, Yibin University, Yibin 644000, China.
The volatility, instability, and water insolubility of essential oil (CLEO) limit its practical applications in the food, pharmaceutical, and cosmetics industries. CLEO nanoemulsions (CLNEs) were formulated and characterized to overcome the aforementioned issues. The volatile compounds of CLEO were identified by gas chromatography-mass spectrometry.
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