Alkaloids of Alstonia plumosa

Nineteen indole alkaloids have been isolated from the root and stem barks of Alstonia plumosa, from New Caledonia. Twelve of them were known compou     

Interaction of phospholipids (Lysophosphatidylethanolamines) with water and sodium cation

We have performed detailed ab initio SCF calculations on the intermolecular interaction energies for one Na⁺ ion and one water molecule with two molecular fragments, one exemplifying a phospholipid (PL) head (PLHD) and the other, a phospholipid tail (PLTL). A 6-12-1 atom-atom pair potential for the interaction of a Na⁺ ion and water with a lysophosphatidyl-ethanolamine (LPEA) was derived from these results by a fitting procedure. This fitted potential was used to obtain isoenergy maps that provide energy profiles of the Na⁺ ion and the water around the phospholipids. The interaction of the Na⁺ ion with PL, as well as the interaction of water with the PL, can be visualized from these maps, which, as expected, show regions of hydrophilicity and hydrophobicity for the water and indicate a very strong binding site for the Na⁺ ion on the phosphate. It appears to be a stationary site that would limit the Na⁺ ion mobility. This binding site is located near the double-bonded oxygen atom of the phosphate group; its binding energy for Na⁺ is 67 kcal/mol. On the other hand the NH⁺ group of PLHD ahows strong electrostatic repulsion of Na⁺ while interacting with water with a binding energy of 13 kcal/mol. This potential energy well region for water is separated from another of similar depth near the phosphate by a barrier and both regions are expected to act as binding sites for water.     

Controlled In Situ Seed-Mediated Growth of Gold and Silver Nanoparticles on an Optical Fiber Platform for Plasmonic Sensing Applications

Plasmonics - This study presents an in situ growth technique to develop highly sensitive plasmonic fiber optic sensors with an excellent control over the plasmonic properties of gold (AuNPs) and...     

Age effects and secular trend in a cross-sectional sample: application to four head dimensions in Belgian adults

If longitudinal studies represent the more direct way to analyze modifications resulting from aging, often for obvious reasons cross-sectional samples can also be used for this purpose. But in this case differences between age groups cannot be identified with the effects of age only; they can also be attributed to the effects of a secular trend. It is the aim of this study to show, using four cephalic dimensions and a cross-sectional sample, the need to take into account the effect of a secular trend when the age effect is studied. In 1985 a study of head and facial measurements of 182 Belgian men, aged 25-54 years, was carried out. A simple comparison between different age groups (F tests) revealed significant differences for head breadth and facial breadths. However, no difference for head length was observed. The amplitude of the secular trend in the Belgian population is already known; thus an easy calculation is proposed to define the effects of the age factor. For head breadth the whole difference seems to be the result of the important decrease of secular trend, whereas the global increase observed for the bizygomatic and bigonial breadths results in part from the decrease resulting from the secular trend and in part from the increase resulting from the age effect.