33 research outputs found
DFT-based Conformational Analysis of a Phospholipid Molecule (DMPC)
The conformational space of the dimyristoyl phosphatidylcholine (DMPC)
molecule has been studied using Density Functional Theory (DFT), augmented with
a damped empirical dispersion energy term (DFT-D). Fourteen ground-state
isomers have been found with total energies within less than 1 kcal/mol.
Despite differences in combinations of their torsion angles, all these
conformers share a common geometric profile, which includes a balance of
attractive, repulsive and constraint forces between and within specific groups
of atoms. The definition of this profile fits with most of the structural
characteristics deduced from measured NMR properties of DMPC solutions. The
calculated vibrational spectrum of the molecule is in good agreement with
experimental data obtained for DMPC bilayers. These results support the idea
that DMPC molecules preserve their individual molecular structures in the
various assemblies.Comment: 31 pages, 6 Tables, 4 Figure
Mercury presence and speciation in the South Atlantic Ocean along the 40°S transect
Mercury (Hg) natural biogeochemical cycle is complex and a significant portion of biological
and chemical transformation occurs in the marine environment. To better understand the presence and
abundance of Hg species in the remote ocean regions, waters of South Atlantic Ocean along 40°S parallel
were investigated during UK-GEOTRACES cruise GA10. Total mercury (THg), methylated mercury (MeHg), and
dissolved gaseous mercury (DGM) concentrations were determined. The concentrations were very low in the
range of pg/L (femtomolar). All Hg species had higher concentration in western than in eastern basin.
THg did not appear to be a useful geotracer. Elevated methylated Hg species were commonly associated
with low-oxygen water masses and occasionally with peaks of chlorophyll a, both involved with carbon
(re)cycling. The overall highest MeHg concentrations were observed in themixed layer (500m) and in the vicinity
of the Gough Island. Conversely, DGM concentrations showed distinct layering and differed between the water
masses in a nutrient-like manner. DGM was lowest at surface, indicating degassing to the atmosphere, and was
highest in the Upper Circumpolar Deep Water, where the oxygen concentration was lowest. DGM increased
also in Antarctic Bottom Water. At one station, dimethylmercury was determined and showed increase in region
with lowest oxygen saturation. Altogether, our data indicate that the South Atlantic Ocean could be a source of
Hg to the atmosphere and that its biogeochemical transformations depend primarily upon carbon cycling and
are thereby additionally prone to global ocean change
Significant lower VVH7-like immunoreactivity serum level in diabetic patients: Evidence for independence from metabolic control and three key enzymes in hemorphin metabolism, cathepsin D, ACE and DPP-IV
International audienc
A6.5â Versatile polyion complex micelles for peptide and sirna vectorization to engineer tolerogenic dendritic cells
International audienc
Solâgel one-pot synthesis in soft conditions of mesoporous silica materials ready for drug delivery system
The present work reveals a new and simple strategy, a one-step solâgel procedure, to encapsulate a low water-soluble drug in silica mesostructured microparticles and to improve its release in physiological media. The synthesis of these new materials is based on the efficient solubilisation of a poorly water-soluble drug in surfactant micelles (Tween 80, a pharmaceutical excipient) which act as template for the silica network. A strict control of the solâgel process and the parameters procedure in soft conditions (concentration, pH, temperature) was applied to reach the solubilisation limit of the drug in the micellar solution so as to optimise its encapsulation. Even if this one-pot procedure could appear limited by the low drug loading, it could provide an interesting alternative for the formulation of many recent highly active but very poorly soluble drugs.Nanostructured MaterialsApplied Science