Search results for "Swell"
showing 10 items of 215 documents
Hyaluronic Acid–Silica Nanohybrid Gels
2013
Excessive water sorption and low mechanical properties are a severe drawback in some biomedical applications of hyaluronic acid (HA). A way to improve these properties is here explored through the novel concept of nanohybrid hydrogels consisting of a HA matrix including different amounts of silica-derived species. This inorganic filler phase controls the mechanical and swelling properties of HA cross-linked matrices. Below a 2 wt % of silica in the systems, nanoparticle aggregates of tens of nanometers and silica oligomers are distributed more or less homogeneously throughout the organic matrix, without percolating. This morphology of the silica phase is accompanied by an increased swelling…
Effect of blastfurnace slag addition to Portland cement for cationic exchange resins encapsulation
2013
In the nuclear industry, cement-based materials are extensively used to encapsulate spent ion exchange resins (IERs) before their final disposal in a repository. It is well known that the cement has to be carefully selected to prevent any deleterious expansion of the solidified waste form, but the reasons for this possible expansion are not clearly established. This work aims at filling the gap. The swelling pressure of IERs is first investigated as a function of ions exchange and ionic strength. It is shown that pressures of a few tenths of MPa can be produced by decreases in the ionic strength of the bulk solution, or by ion exchanges (2Na + instead of Ca 2+ , Na + instead of K + ). Then,…
Interlamellar Reactions of Tetracalcium Aluminate Hydrates with Water and Organic Compounds
1967
Tetracalcium aluminate hydrates are the first example of layer-structured crystals containing neutral sheets, which are highly capable of interlamellar adsorption of water and neutral organic compounds. In this respect tetracalcium aluminate hydrates present new aspects of the phenomenon of swelling, and bring about the challenge of comparison with the frequently examined clay-organic compounds. This report is concerned with the probable monolayer structure of tetracalcium aluminate hydrate which forms five hydration stages. A summary concerning configuration and properties of adsorption complexes with approximately 500 selected organic substances follows. As far as these substances are hom…
Various types of polysiloxanes studied by positron annihilation lifetime spectroscopy
2014
Abstract In the work, linear poly(vinylsiloxanes) with regular distributions of vinyl groups along chains, the networks obtained by their hydrosilylation with various hydrogensiloxanes, products of pyrolysis of such networks as well as the networks prepared via reaction of low-molecular siloxanes have been studied by positron anihilation lifetime spectroscopy (PALS). Based on free volume sizes determined by this method, relations between cross-link densities in the investigated systems have been established. They have been compared with the results of swelling experiments conducted in the work and to efficiency of cross-linking reaction evaluated in our previous FTIR investigations of the s…
Influence of layer structure preservation on the catalytic properties of the pillared zeolite MCM-36
2010
MCM-36 is a catalytically active material made by swelling and subsequent pillaring of a layered zeolite precursor, MCM-22(P). However, the swelling procedures lead to significant destruction of layer structure and alteration of framework silicon/aluminum (Si/Al) ratio, which are likely to influence the acidity and catalytic activity of the final materials. We report a milder swelling and pillaring process to prevent such structural destruction. The resulting pillared materials show higher crystallinity and improved retention of the zeolitic layer structure when compared to the ones prepared by the previously reported methods involving more aggressive treatments. Implications of such struct…
Einfluß der quellung in aceton auf das kernresonanzspektrum von polyäthylenterephthalat
1971
Die Kernresonanzspektren isotherm kristallisierter Proben von Polyathylenterephthalat wurden vor und nach der Quellung in deuteriertem Aceton als Funktion der Temperatur gemessen. Anschliesend wurde jedes Spektrum in eine breite und eine schmale Komponente zerlegt. Es zeigt sich, das durch die Quellung der Einfrierbereich verbreitert und die Einfriertemperatur erniedrigt wird. Diese Erniedrigung ist von den Kristallisationsbedingungen unabhangig. Die Linienbreite der schmalen Komponente wird durch die Quellung leicht erhoht, was fur eine Zunahme der Kettenverspannung in den nichtkristallinen Bereichen spricht. Das zweite Moment der breiten Komponente wird durch die Quellung erniedrigt. Dara…
Influence of brine concentration on swelling pressure of pork meat throughout salting.
2009
Abstract The influence of sodium chloride on the water holding capacity of meat is well known and described in literature. An increase in water holding capacity is associated with an increase in the swelling pressure in the protein matrix. A novel device was used to measure the swelling pressure during brine salting of muscle cylinders (40 × 50 mm), in different NaCl brine concentrations (2.5 to 25%) over 6 days at 4 °C. Changes in meat composition, weight and height of non-constrained control samples were also measured. The aim of this work was to prove the feasibility of using the developed device in order to quantify the influence of the brine concentration on the magnitude of the swelli…
Agarose/κ-carrageenan-based hydrogel film enriched with natural plant extracts for the treatment of cutaneous wounds.
2020
Abstract Hydrogels for complex and chronic wound dressings must be conformable, absorb and retain wound exudates and maintain hydration. They can incorporate and release bioactive molecules that can accelerate the healing process. Wound dressings have to be in contact with the wound and epidermis, even for long periods, without causing adverse effects. Hydrogel dressing formulations based on biopolymers derived from terrestrial or marine flora can be relatively inexpensive and well tolerated. In the present article hydrogel films composed by agarose (1.0 wt%), κ-carrageenan at three different concentrations (0.5, 1.0 and 1.5 wt%) and glycerol (3.0 wt%) were prepared without recourse to cros…
Increased Stability of Rubber-Modified Asphalt Mixtures to Swelling, Expansion and Rebound Effect during Post-Compaction
2017
The application of bituminous mixtures modified with rubber from scrap-tires require attention and care during mixing and compaction. Rubber modifies the properties because it reacts in the internal structure of bitumen at high temperatures changing the performance of the mixture (interaction process of solvents with binder-rubber aggregate). The main change is the increasing of the viscosity and elasticity of the binder due to the larger sizes of the rubber particles by dry process but, this positive effect is counteracted by short mixing times, compared to wet technology, and due to the transport processes, curing time and post-compaction of the mixtures. Therefore, negative effects as sw…
Aloin delivery on buccal mucosa: ex vivo studies and design of a new locoregional dosing system
2014
Context: Chemoprevention of potential malignant disorders or cancerous lesions that affect oral mucosae requires extended duration of treatment. Locoregional delivery of natural products could represent a promising strategy for this purpose. Objective: To investigate the aptitude of aloin to permeate through, or accumulate in, the buccal mucosa and to develop a new prolonged oro-mucosal drug delivery system. Materials and Methods: Permeation/accumulation of aloin from Curacao Aloe (containing 50% barbaloin) was evaluated ex vivo, using porcine buccal mucosa as the most useful model to simulate human epithelium. Oro-mucosal matrix tablets were prepared by dispersing aloin (10% w/w) in Eudrag…