40 research outputs found
Antimicrobial peptide encapsulation and sustained release from polymer network particles prepared in supercritical carbon dioxide
© 2018 Antimicrobial peptide loaded poly(2-hydroxyethyl methacrylate) particles were synthesized in supercritical carbon dioxide via one-pot free-radical dispersion polymerisation of 2-hydroxyethyl methacrylate and a cross-linker. Discrete particles with a well-defined spherical morphology and a diameter as low as 450 nm have been obtained in mild conditions. The encapsulation and release of the peptide were confirmed by antimicrobial tests that demonstrated for the first time a sustained release of the peptide from poly(2-hydroxyethyl methacrylate) microgels prepared by one-pot dispersion polymerization in supercritical carbon dioxide and then dispersed in water
Adiabatic invariants and Mixmaster catastrophes
We present a rigorous analysis of the role and uses of the adiabatic
invariant in the Mixmaster dynamical system. We propose a new invariant for the
global dynamics which in some respects has an improved behaviour over the
commonly used one. We illustrate its behaviour in a number of numerical
results. We also present a new formulation of the dynamics via Catastrophe
Theory. We find that the change from one era to the next corresponds to a fold
catastrophe, during the Kasner shifts the potential is an Implicit Function
Form whereas, as the anisotropy dissipates, the Mixmaster potential must become
a Morse 0--saddle. We compare and contrast our results to many known works on
the Mixmaster problem and indicate how extensions could be achieved. Further
exploitation of this formulation may lead to a clearer understanding of the
global Mixmaster dynamics.Comment: 24 pages, LaTeX, 5 figures (which can be obtained by sending a
message to the first author), submitted to Phys.Rev.
About Major Alkaloids of Strychnos Scheffleri from Zaire.
Leaves and stem barks of S. SCHEFFLERI G ILG afforded eight dihydroindole alkaloids. Four tertiary monomers (O-methyl Na-acetylstrychnosplendine, Na-acetylstrychnosplendine, strychnobrasiline and strychnofendlerine) have been isolated from leaf material while stem barks yielded one tertiary monomer (desacetylisoretuline), one tertiary symmetrical dimer (bis-nordihydrotoxiferine) and two quaternary monomers (mavacurine and fluorocurine)
Limitation du nombre de sociétés: Qu'en est-il des sociétés de capitaux (SA, SPRL, SCRL)?
peer reviewe
The Isolation and Structure Elucidation of Afrocurarine
The structure and the stereochemistry of afrocurarine (a new unsymmetrical bisindole alkaloid) previously isolated from S. USAMBARENSIS Gilg. are established especially from (1)H-NMR spectroscopic data. The separation of quaternary alkaloids has always been very tedious. Ion-pair reversed-phase column chromatography applied to the purification of afrocurarine is proved very useful and seems to be a suitable technique in quaternary alkaloid research