Structure-barrier property relationship of biodegradable poly(butylene succinate) and poly[(butylene succinate)-co-(butylene adipate)] nanocomposites: influence of the rigid amorphous fraction.

Composites composed of polyesters, poly(butylene succinate) (PBS) or poly[(butylene succinate)-co-(butylene adipate)] (PBSA), and 5 wt% of montmorillonite (CNa) or organo-modified montmorillonite (C30B) were melt-processed and transformed into films by either compression-molding or extrusion-calendering. XRD, rheological measurements and TEM images clearly indicated that films containing CNa are microcomposites, while nanocomposites were observed for those containing C30B. Using Flash DSC, it was possible, for the first time, not only to measure the heat capacity step at the glass transition of these two materials in their amorphous state, but also to investigate whether the preparation technique influenced the Rigid Amorphous Fraction (RAF) in our PBS- and PBSA-based nanocomposites. In this work, we have successfully shown the correlation between the microstructure of the films and their barrier properties, and especially the role played by the RAF. Indeed, the lowest permeabilities to gases and to water were determined in the films containing the highest RAF in both PBS- and PBSA-based materials.

High performance recycled CFRP composites based on reused carbon fabrics through sustainable mild solvolysis route.

A novel environmentally friendly recycling method is developed for large carbon-fibers reinforced-polymers composite panels whose efficiency is demonstrated through a proof-of-concept fabrication of a new composite part based on recycled fibers. The recycling process relies on formic acid as separation reagent at room temperature and atmospheric pressure with efficient recycling potential of the separating agent. Electron microscopy and thermal analysis indicate that the recycled fibers are covered by a thin layer of about 10wt.% of residual resin, alternating with few small particles, as compared to the smooth virgin fibers. The recycled composites show promising shear strength and compression after impact strength, with up to 93% retention of performance depending on the property as compared to the reference. The recycled carbon fibers can thus be reused for structural applications requiring moderate to high performances. The loss of properties is attributed to a lower adhesion between fresh epoxy resin and recycled carbon fibers due to the absence of sizing, partly compensated by a good interface between fresh and residual cured epoxy thanks to mechanical anchoring as well as chemical reactions. The room temperature and atmospheric pressure operating conditions combined to the recyclability of the forming acid contribute to the sustainability of the entire approach.

Fast separation of the three main plasma lipoprotein classes by ultracentrifugation using vertical rotor and multiple discontinuous density gradient.

An ultracentrifugation technique for isolation of the various lipoprotein fractions using a vertical rotor is described. By the use of a multiple discontinuous density gradient, very low density lipoproteins, low density lipoproteins and high density lipoproteins are sharply separated, without contamination of other lipoproteins or albumin. Centrifugation time is 80 min. The densities, electrophoretic mobilities, electron microscopic appearance and chemical composition are those of the expected classes of lipoproteins. Two different gradients are used to enhance the separation of very low density lipoproteins from low density lipoproteins on one hand and high density lipoproteins from infranatant on the other.

The metabolic fate of 14C or 35S labelled tiadenol in rabbit after i.v. and oral administration.

Tiadenol is a hypocholesterolemic drug that inhibits the early steps of cholesterol synthesis. No pharmacokinetic data have thus far been reported for man and few for animals. We investigated the pharmacokinetics, biotransformation and distribution of two differently labelled tiadenol molecules (14C and 35S) in the rabbit. Following a short protocol (up to 8 h), a regular decrease of the plasma radioactivity was observed after i.v. route for 4 or 5 h and plateaued thereafter. Most of the radioactivity was found in the urine, the lungs and the liver with low levels in bile and feces. By oral route, the plasma radioactivity increased regularly and decayed for a short period. Thereafter, a second increase was observed. Drug and metabolites accumulated in the kidneys and in the liver but most of the radioactive compounds were recovered from the urine. From results obtained with a longer protocol (4 days in a metabolic cage), it could be extrapolated that 10 to 15 days are necessary to completely clear the drug. Tiadenol was extensively metabolized with a wide tissue distribution. The main metabolites identified were oxidation products (free or conjugated). No statistically significant differences in biotransformation were found between the two differently labelled tiadenol molecules.

Absolute bioavailability of mianserin tablets and solution in healthy humans.

A pharmacokinetic study with mianserin . HCl was performed in six healthy male subjects. The subjects were treated on different occasions intravenously with a constant-rate infusion of 5 mg mianserin. HCl in 1 h, orally with a single dose of 60 mg as two tablets of 30 mg each and with 60 mg as an oral solution. The wash-out period between treatments was 1 month. Blood samples were taken at predetermined times over a period of 120 h following dosing. The mianserin concentration in the plasma samples was determined and the results were pharmacokinetically analyzed. The intravenous data could be adequately described by a 3-compartment model and the oral data by a 2-compartment model, both with first-order transfer and elimination rate constants. The mean plasma clearance of mianserin was found to be 19 +/- 2 l h-1 (mean +/- SEM), the kinetic volume of distribution 444 +/- 250 l, the steady-state volume of distribution 242 +/- 171 l and the elimination half-life 33 +/- 5 h. The absolute bioavailability in terms of extent of absorption was 22 +/- 3% for the solution and 20 +/- 3% for the tablets. The mean peak level for the solution was 79 +/- 11 ng X ml-1 and for the tablets 54 +/- 5 ng X ml-1; mean peak time for the solution was 1.1 +/- 0.2 h and for the tablets 1.4 +/- 0.2 h. The mean absorption half-life for the solution was 0.43 +/- 0.13 h and for the tablets 0.39 +/- 0.11 h.(ABSTRACT TRUNCATED AT 250 WORDS)