Search results for "CHIMIE"
showing 10 items of 170 documents
Relationship between olfactory reactivity and food rejections in infants
2006
N° 261; The role of hedonic reactions to odours on determining rejections of foods in infants is still debated. To answer this question, the first requirement is to have an instrument to test infants’ olfactory reactivity. Indeed, except in neonates, there is a lack of validated method. This study presents results of a new method designed to assess olfactory reactivity of 7- to 8-month-old infants. This method is based on the observation of infants’ reactions while they explored different rattles. The rattles were visually identical but differed in their odours (neutral or with a food odour). Two sequences of 6 rattles were presented to each infant. Eight odorants were used. Four odorants w…
Apport de matières organiques exogènes en agriculture: indicateur de potentialité de stockage de carbone dans les sols et définition de classes de di…
2007
CT3; absent
Soil carbon, multiple benefits
2014
Made available in DSpace on 2018-12-11T17:24:47Z (GMT). No. of bitstreams: 0 Previous issue date: 2015-01-01 In March 2013, 40 leading experts from across the world gathered at a workshop, hosted by the European Commission, Directorate General Joint Research Centre, Italy, to discuss the multiple benefits of soil carbon as part of a Rapid Assessment Process (RAP) project commissioned by Scientific Committee on Problems of the Environment (SCOPE). This collaboration led to the publication of the SCOPE Series Volume 71 Soil Carbon: Science, Management and Policy for Multiple Benefits; which brings together the essential scientific evidence and policy opportunities regarding the global importa…
In situ Mössbauer spectroscopy: Evidence for green rust (fougerite) in a gleysol and its mineralogical transformations with time and depth
2005
Abstract A miniaturized Mossbauer spectrometer, adapted to the Earth’s conditions from the instrument developed for Mars space missions, has been used for the first time to study in situ variations with depth and transformations with time of iron minerals in a gleysol. The instrument is set into a PVC tube and can be moved up and down precisely (±1 mm) at the desired depth. Mossbauer spectra were obtained from 15 to 106 cm depth and repeated exactly at the same point at different times to follow mineralogical transformations with time. X-ray diffraction (XRD) and selective extraction techniques were performed on soil samples. The piezometric level of the water table was measured and the com…
Morphological characterisation of soil structure in tilled fields: from a diagnosis method to the modelling of structural changes over time
2004
Characterisation of soit structure within the tilled layer of cultivated fields is crucial because the importance of this soil characteristic on the biological, chemical and physical properties of the soil and its repercussions on water cycle, root growth and functioning. We present in this paper a method for field characterisation of soil structure. This method, practised since the 1970s, was designed for field diagnosis of the effects of cropping systems on soil structure. It is based on a stratification of the observation face of a pit dug perpendicular to the direction of tillage and traffic: spatial compartments are distinguished, according to the nature of the mechanical stresses they…
Chemistry of pheromonal and defensive secretions in the nymphs and the adults ofDysdercus cingulatus Fabr. (Heteroptera, Pyrrhocoridae)
1991
59 ref.; International audience; The exocrine secretions from the nymphs and the adults of both sexes in D. cingulatus were chemically investigated. Seven compounds were identified in the anterior glands, and eleven in the median dorsoabdominal glands of nymphs and adults of both sexes. Fifty-five compounds were identified in the defensive glands (34 in posterior dorsoabdominal glands ofnymphs and 21 in metathoracic glands of adults), and six in the sternal glandular epithelium of the males. The biological function of the glandular secretions and of their identified compounds were investigated and are discussed.
Solid-solid phase transition in hard ellipsoids
2009
We present a computer simulation study of the crystalline phases of hard ellipsoids of revolution. A previous study [P. Pfleiderer and T. Schilling, Phys. Rev. E 75, 020402 (2007)]. showed that for aspect ratios a/bor=3 the previously suggested stretched-fcc phase [D. Frenkel and B. Mulder, Mol. Phys. 55, 1171 (1985)] is unstable with respect to a simple monoclinic phase with two ellipsoids of different orientations per unit cell (SM2). In order to study the stability of these crystalline phases at different aspect ratios and as a function of density we have calculated their free energies by thermodynamic integration. The integration path was sampled by an expanded ensemble method in which …
Gravity-induced liquid crystal phase transitions of colloidal platelets.
2004
he influence of gravity on a suspension of sterically stabilized colloidal gibbsite platelets is studied. An initially isotropic-nematic biphasic sample of such a suspension develops a columnar phase on the bottom on prolonged standing. This phenomenon is described using a simple osmotic compression model. We performed Monte Carlo simulations of cut spheres with aspect ratio L/D = 1/15 and took data from the literature to supply the equations of state required for the model. We find that the model describes the observed three-phase equilibrium quite well.
Tuning the defect configurations in nematic and smectic liquid crystalline shells
2013
Thin liquid crystalline shells surrounding and surrounded by aqueous phases can be conveniently produced using a nested capillary microfluidic system, as was first demonstrated by Fernandez-Nieves et al. in 2007. By choosing particular combinations of stabilizers in the internal and external phases, different types of alignment, uniform or hybrid, can be ensured within the shell. Here, we investigate shells in the nematic and smectic phases under varying boundary conditions, focusing in particular on textural transformations during phase transitions, on the interaction between topological defects in the director field and inclusions in the liquid crystal (LC), and on the possibility to rel…
Synthesis of ortho-fonctionnalized arylphosphines and their applications
2020
This thesis reports with the synthesis of ortho-functionnalized phosphines bearing phosphonium and 1,2,3-triazole moieties.The synthesis of phosphines-phosphoniums, using as key-step Phospha-Fries rearrangement and Appel reaction is described. Eight new phosphines- phosphoniums, bearing aryl, alkyl or ferrocenyl fragments on the phosphonium part, have been prepared with overall yields reaching 48%. These phosphines- phosphoniums have been used in the preparation of gold (I) complexes which have been characterized using spectroscopic methods and X ray diffraction. Both gold (I) complexes and phosphines-phosphoniums have been studied in biology and these compounds turned out to be cytotoxic i…