Search results for "PULMONARY"
showing 10 items of 3030 documents
Thermodynamic and kinetic properties of water–oil–surfactant mixtures
1998
Abstract We present experimental data on thermodynamic and kinetic properties of the emulsification failure of a droplet-phase microemulsion, and model them by a bending free energy. In contrast to most other models used to describe water–oil–surfactant mixtures no entropic contributions are included in the present description. Still, there is quantitative agreement between theory and measurements, even though there are no free parameters in our model – only experimentally accessible material constants appear.
Dry adsorbed emulsion: 2. Dissolution behaviour of an intricate formulation
2002
The behaviour of a pharmaceutical form, called dry adsorbed emulsion (DAE), containing a sparingly soluble drug (i.e. theophylline) was studied for dissolution drug release kinetic, in relation with DAE structure characterisation. In vitro dissolution testings were performed under different experimental conditions (medium at pH 1.2 and 7.4, medium with or without surfactant addition, different particle sizes, discrete or densified particles). Discrete DAE particles showed an extended release, in comparison with the native drug powder, depending on both drug solubility in the medium and particle size. The relevance of dissolution data was not improved by surfactant addition (0.1% sodium laur…
Effect of self-assembled surfactant structures on ion transport across the liquid|liquid interface
1999
In this paper, the effect of a coadsorbed polyanion–cationic surfactant system on the transport of tetraethylammonium ion across the water|1,2-dichloroethane interface is studied. It is shown that the change in double-layer structure due to the presence of adsorbed or coadsorbed surfactant can explain the experimental observations, thus concluding that no other effects on ion transfer (e.g., steric hindrance) are relevant under these experimental conditions. The implications of these results are discussed. Keywords: ITIES, Ion transfer, Self-assembled monolayers, Surfactants, Double-layer effects
Self-assembly in surfactant-based mixtures driven by acid–base reactions: bis(2-ethylhexyl) phosphoric acid–n-octylamine systems
2013
Structural and dynamic features of bis(2-ethylhexyl) phosphoric acid (HDEHP)-n-octylamine (NOA) mixtures as a function of the NOA mole fraction (X-NOA) have been investigated by SAXS, WAXS, IR, dielectric spectroscopy and polarized optical microscopy. In the 0 <= X-NOA < 0.5 range, mixtures are transparent liquids, while the abrupt formation of a waxy solid characterized by an hexagonal bidimensional structure occurs at X-NOA = 0.5. Such a composition-induced phase transition results from the synergetic effect of the progressive increase in number density of ordered HDEHP-NOA nanodomains with X-NOA. Mainly driven by an HDEHP to NOA proton transfer, the increase of structural order with X-NO…
Easy removal of a large mucus plug with a flexible paediatric bronchoscope after administration of rhDNase (Pulmozyme).
2006
Mucoid impaction and plastic bronchitis are relatively rare disorders affecting patients of any age. Here we report the case of mucoid impaction developing in a four-year-old child as a complication of pneumonic infection treated four weeks prior. p.a. chest X-ray and fiberoptic bronchoscopy showed atelectasis and the location of a mucus cast in the left upper lobe. After extraction of the cast via the suction channel of the bronchoscope had failed, we administered 2.5 mg of undiluted recombinant human deoxyribonuclease (rhDNase) instilled directly over the affected area of occlusion for 15 minutes. This mucolytic agent mobilized the cast by reducing viscoelasticity and adherence of mucus. …
Effective recovery of perfluoropolyether surfactants from PVDF and PTFE by supercritical carbon dioxide extraction
2007
Abstract The extraction of ammonium carboxylate perfluoropolyether surfactants from poly(vinylidenefluoride) (PVDF) and poly(tetrafluoroethylene) (PTFE) was performed with supercritical carbon dioxide. When proper conditions in terms of temperature, pressure and flow rate were used, extraction recoveries higher than 90% were obtained. For PVDF (with a concentration of surfactant of 5% w/w), at low pressure (12 MPa) and 40 °C, more than 100 min are necessary to have a quantitative extraction. On the other hand, at higher pressure (20 MPa) a quantitative recovery was obtained after few minutes. A strong influence of the temperature on the extraction recovery was also found. In the case of PTF…
Dispersion Copolymerization of Vinyl Monomers in Supercritical Carbon Dioxide.
2003
The thermally initiated free-radical dispersion copolymerization of methyl methacrylate (MMA) and N,N-dimethylacrylamide (DMA) in supercritical carbon dioxide has been studied in the presence of polysiloxane surfactants. The formation of a stable latex seems to be related to the presence of at least one reactive end group in the surfactant macromolecule, thus suggesting that anchoring of the stabilizer to the surface of the growing polymer particles occurs through chemical grafting. In the case of a molar ratio of DMA to MMA lower than 0.40, microspherical copolymer particles with yields ranging from 81 to 97% were collected from batch polymerizations carried out at 65 °C and 23-28 MPa usin…
Disentangling cardiovascular control mechanisms during head-down tilt via joint transfer entropy and self-entropy decompositions
2015
A full decomposition of the predictive entropy (PE) of the spontaneous variations of the heart period (HP) given systolic arterial pressure (SAP) and respiration (R) is proposed. The PE of HP is decomposed into the joint transfer entropy (JTE) from SAP and R to HP and self-entropy (SE) of HP. The SE is the sum of three terms quantifying the synergistic/redundant contributions of HP and SAP, when taken individually and jointly, to SE and one term conditioned on HP and SAP denoted as the conditional SE (CSE) of HP given SAP and R. The JTE from SAP and R to HP is the sum of two terms attributable to SAP or R plus an extra term describing the redundant/synergistic contribution to the JTE. All q…
2D dynamical arrest transition in a mixed nanoparticle-phospholipid layer studied in real and momentum spaces
2015
AbstractWe investigate the interfacial dynamics of a 2D self-organized mixed layer made of silica nanoparticles interacting with phospholipid (DPPC) monolayers at the air/water interface. This system has biological relevance, allowing investigation of toxicological effects of nanoparticles on model membranes and lung surfactants. It might also provide bio-inspired technological solutions, exploiting the self-organization of DPPC to produce a non-trivial 2D structuration of nanoparticles. The characterization of interfacial dynamics yields information on the effects of NPs on the mechanical properties, important to improve performances of systems such as colloidosomes, foams, creams. For thi…
Different Dissolution Media Lead to Different Crystal Structures of Talinolol with Impact on Its Dissolution and Solubility
2003
During the performance of dissolution tests with immediate and controlled-release talinolol tablets it was detected that the type of the buffer used as dissolution medium had a strong influence on the solubility and the dissolution behavior of the drug. It was proven that talinolol appeared in different crystal structures with strongly differing solubilities when pure water, acetate, or phosphate buffers were employed as dissolution media. The resulting crystal structures were characterized by means of light microscopy, differential scanning calorimetry, and X-ray powder diffraction. All methods were adjuvant to detect changes in talinolol crystal structures. The different solubility and di…