Search results for "Solubility"
showing 10 items of 681 documents
Dopant solubility in ceria: alloy thermodynamics combined with the DFT+U calculations
2018
This research was partly funded by the Russian Science Foundation (under the project 14-43-0005) and ERA-NET HarvEnPiez project, with the computer resources provided by Stuttgart Supercomputing Centre (Project DEFTD 12939). A. C. also acknowledges financial support from the University of Latvia Foundation (Arnis Riekstins’s ‘‘MikroTik’’ donation). Authors thank R. Merkle, A. Popov for fruitful discussions.
Glassy PEEK‐WC vs Rubbery Pebax®1657 Polymers: Effect on the Gas Transport in CuNi‐MOF Based Mixed Matrix Membranes
2020
Mixed matrix membranes (MMMs) are seen as promising candidates to overcome the fundamental limit of polymeric membranes, known as the so-called Robeson upper bound, which defines the best compromise between permeability and selectivity of neat polymeric membranes. To overcome this limit, the permeability of the filler particles in the MMM must be carefully matched with that of the polymer matrix. The present work shows that it is not sufficient to match only the permeability of the polymer and the dispersed phase, but that one should consider also the individual contributions of the diffusivity and the solubility of the gas in both components. Here we compare the gas transport performance o…
Equilibrium phase behavior of polyethylene oxide and of its mixtures with tetrahydronaphthalene or/and poly(ethylene oxide-block-dimethylsiloxane)
2002
Liquid/solid and liquid/liquid (LL) transition temperatures were measured by means of an automated device that monitors the light passing through the systems as a function of T at different constant cooling or heating rates q. For pure polyethylene oxide (PEO) crystallization and melting temperatures depend on |q|0.3 and become identical at the equilibrium transition temperature Tm=61.0 °C in the limit of infinitely slow cooling/heating. The reduction of Tm for PEO dissolved in tetrahydronaphthalene (THN) yields information on the Flory–Huggins interaction parameter ξ between these two compounds; ξ results negative and decreases markedly with rising polymer concentration. A tentative explan…
Fixed Bed Adsorption of Drugs on Silica Aerogel from Supercritical Carbon Dioxide Solutions
2013
Supercritical adsorption coupled with the high adsorption capacity of silica aerogel allows the preparation of a new kind of delivery systems of poor water soluble drugs. In order to overcome drawbacks of conventional techniques where the use of liquid solvents can cause the fracture of aerogel porous structure, in this work a new adsorption process of drugs from a supercritical mixture is proposed. Adsorption takes place from a fluid solution of the drug in supercritical CO2and ethanol as cosolvent. A fixed bed adsorption plant has been developed to allow fast mixing of fluid phase and effective contact in the adsorption column. The use of ethanol as cosolvent allows to overcome the limita…
Chitosan-based smart hybrid materials: a physico-chemical perspective.
2020
Chitosan is one of the most studied cationic polysaccharides. Due to its unique characteristics of being water soluble, biocompatible, biodegradable, and non-toxic, this macromolecule is highly attractive for a broad range of applications. In addition, its complex behavior and the number of ways it interacts with different components in a system result in an astonishing variety of chitosan-based materials. Herein, we present recent advances in the field of chitosan-based materials from a physico-chemical perspective, with focus on aqueous mixtures with oppositely charged colloids, chitosan-based thin films, and nanocomposite systems. In this review, we focus our attention on the physico-che…
Engineering of Nanofibrous Amorphous and Crystalline Solid Dispersions for Oral Drug Delivery
2018
Poor aqueous solubility (<0.1 mg/mL) affects a significant number of drugs currently on the market or under development. Several formulation strategies including salt formation, particle size reduction, and solid dispersion approaches have been employed with varied success. In this review, we focus primarily on the emerging trends in the generation of amorphous and micro/nano-crystalline solid dispersions using electrospinning to improve the dissolution rate and in turn the bioavailability of poorly water-soluble drugs. Electrospinning is a simple but versatile process that utilizes electrostatic forces to generate polymeric fibers and has been used for over 100 years to generate synthet…
Controlling Multicompartment Morphologies Using Solvent Conditions and Chemical Modification
2016
The solution self-assembly of amphiphilic diblock copolymers into spheres, cylinders, and vesicles (polymersomes) has been intensely studied over the past two decades, and their morphological behavior is well understood. Linear ABC triblock terpolymers with two insoluble blocks A/B, on the other hand, display a richer and more complex morphological spectrum that has been recently explored by synthetic block length variations. Here, we describe facile postpolymerization routes to tailor ABC triblock terpolymer solution morphologies by altering block solubility (solvent mixtures), blending with homopolymers, and block-selective chemical reactions. The feasibility of these processes is demonst…
Bioaccessibility of minerals in school meals: Comparison between dialysis and solubility methods
2005
Abstract Determinations have been made of content and bioaccessibility of Ca, Fe, Zn and Cu in 13 dishes collected from a catering service delivering to a school. Bioaccessibility was estimated by measuring the soluble or dialyzable mineral fraction resulting from in vitro gastrointestinal digestion of the meal. The analyzed dishes had mineral contents (μg/g) in the following ranges: Ca (74.1–913), Fe (2.8–17.9), Zn (2.8–13.1), Cu (0.28–1.90). Mineral solubility and dialysis percentages were as follows: Ca (1.7–96.2; 0.75–61.3), Fe (16.0–97.8; 0.23–19.0), Zn (22.6–93; 5.78–31.45), Cu (35.7–92.3; 0.66–25.0). The highest bioaccessible Ca content corresponded to fish-based dishes, while vegeta…
Membrane-penetrating Domain of Streptolysin O Identified by Cysteine Scanning Mutagenesis
1996
Streptolysin O (SLO), a polypeptide of 571 amino acids, belongs to a family of highly homologous toxins that bind to cell membranes containing cholesterol and then polymerize to form large transmembrane pores. A conserved region close to the C terminus contains the single cysteine residue of SLO and has been implicated in membrane binding, which has been the only clear assignment of function to a part of the sequence. We have used a cysteine-less active mutant of SLO to introduce single cysteine residues at 19 positions distributed throughout the sequence. The cysteines were derivatized with the polarity-sensitive fluorophore acrylodan, and the fluorescence emission of the label was examine…
Lipid dependence of diadinoxanthin solubilization and de-epoxidation in artificial membrane systems resembling the lipid composition of the natural t…
2006
In the present study, the solubility and enzymatic de-epoxidation of diadinoxanthin (Ddx) was investigated in three different artificial membrane systems: (1) Unilamellar liposomes composed of different concentrations of the bilayer forming lipid phosphatidylcholine (PC) and the inverted hexagonal phase (H(II) phase) forming lipid monogalactosyldiacylglycerol (MGDG), (2) liposomes composed of PC and the H(II) phase forming lipid phosphatidylethanolamine (PE), and (3) an artificial membrane system composed of digalactosyldiacylglycerol (DGDG) and MGDG, which resembles the lipid composition of the natural thylakoid membrane. Our results show that Ddx de-epoxidation strongly depends on the con…