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International audience; This review paper highlights how supercritical fluid technology applied to materials processing can play a great role in materials science. It is shown that this way of materials processing offers the possibility of controlling the synthesis by varying operating parameters. Understanding how each parameter influences the synthesis process allows one to control the characteristics of the material, in terms of size, morphology, structure and composition. It is equally shown how these operating parameters influence the properties of the material, and therefore their applications in numerous technologically important fields such as energy, chemistry, electronics, optics and pharmacology.

The aim of this paper is to introduce SCF studies as a domain in which fundamental and applied researches can strongly overlap, thereby offering an original approach to stimulate interdisciplinary cross-studies. After a general presentation of supercritical fluids, some specific properties will be illustrated at the molecular level from the study of typical neat SCF and binary mixtures using vibrational spectroscopy and modelling. This part will be followed by a presentation of current researches at a macroscopic level on materials elaborated in supercritical media namely fine particle and porous materials synthesis and surface modifications.

Single-step synthesis of ultra-fine barium titanate powder with a crystallinity as high as 90% and without barium carbonate contamination has been successfully performed under supercritical conditions using a continuous-flow reactor in the temperature range 150–380 °C at 16 MPa. To synthesize this bimetallic oxide, alkoxides, ethanol and water were used. The influence of the synthesis parameters on the BaTiO3 powder characteristics was investigated. The results show that the water to alkoxide precursor ratio, the reactor temperature and the Ba:Ti molar ratio of alkoxide precursor play a major role in the crystallization of pure and well-crystallized BaTiO3 nanoparticles. The continuous mode of operation without post-treatments for powder washing, drying or crystallization increase the industrial interest.

International audience

P hospholipases D (PLD) catalyse hydrolysis and transphosphatidylation reactions in phospholipids. In the present study, the hydrolytic activity for cabbage PLD was investigated with five different substrates (dipalmitoylphosphatidylethanolamine (DPPE), dipalmitoylphosphaticlylcholine (DPPC), didecanoylphosphatidylcholine (DDPC), 1-alkyl-2-acetyl-sn-glycero-3-phosphocholine and lyso-phosphaticlylcholine (lyso-PC)) in solution or adsorbed on a silica matrix. In the specific buffer solutions, where the substrates were proved to form large multilamellar polydisperse aggregates, PLD showed preference for DPPC > DPPE > DDPC > alkyl-2-acetyl-sn-glycero-3-phosphocholine > lyso-PC. When the substrates were adsorbed on the silica matrix, PLD hydrolysed 1-alkyl-2-acetyl-sn-glycero-3-phosphocholine and lyso-PC, DDPC, but not DPPC or DPPE. Theoretical studies of the simplest possible adducts between the phospholipids and the silica matrix were performed. Examination of local geometries of DPPC showed a significant blocking of the P-O-X bond-prone to hydrolysis, which could possibly block the access of PLD. Immobilization of phospholipids could be applied for improving the yield of reactions catalysed by PLD as well as for performing a targeted production of short-chain length phosphatidic acid analogs. (c) 2005 Elsevier Ireland Ltd. All rights reserved. Chemistry and Physics of Lipids

The management of asymptomatic carotid stenosis remains unclear in terms of screening as well as of treatment. The degree of carotid stenosis is not enough to clarify the debate. It seems useful to search among severe carotid stenosis parameters indicating higher ipsilateral stroke risk. Duplex ultrasound and transcranial Doppler offer this opportunity with a diagnostic battery allowing to evaluate hemodynamical risk (degree of stenosis, common carotid flow, MCA signal, cerebral vasoreactivity), thrombo-embolic risk (echostructure of the stenosis, micro-embolic signals, HITS) and progression of the stenosis.

The dynamic structure of a chemically end-grafted polystyrene brush bathed in solvents of varying interactions was studied by evanescent wave dynamic light scattering. It reveals distinct behavior under good and poor solvent conditions. The cooperative diffusion is a generic feature of a good solvent environment, whereas a second slow relaxation mode appears in the theta solvent regime. Its characteristics resemble self-diffusion of clusters in a gel while weak concentration fluctuations in the polymer brush decay similarly to a semidilute polymer solution.

International audience; Les fluides supercritiques possèdent des propriétés particulières qui sont exploitées pour le développement de nouvelles réactions, en particulier dans le domaine de la synthèse de matériaux...

Some supercritical fluids are able to replace toxic industrial solvents. So, from an industrial point of view, supercritical fluids are widely used in many fields such as pharmacy, food industry and environment. From a scientific point of view, the main interest of supercritical fluids is connected to the possibility to adjust continuously the physicochemical properties of these reactive media, such as selectivity, solvation, solubility or reactivity. In this paper, we present recent work on processes using supercritical media for processing materials related to fine particle synthesis, porous materials synthesis, polymer synthesis and surface modifications.

Hypolipidemic pharmacophoric moieties of statins, fibrates, ACAT inhibitors and beta-sitosterol analog series were identified by computational modeling, and compared with the computed structure of new potential glycyrrhetinic acid derivatives lipid-lowering drugs. Their electronic and geometric domains, similar to those of fibrates, suggest a fibrate -like mechanism matching biochemical data.

Crowded solutions of multiarm star polymers, representing model colloidal spheres with ultrasoft repulsive interactions, undergo a reversible gelation transition upon heating in solvents of intermediate quality (between good and Theta). This unusual phenomenon is due to the kinetic arrest of the swollen interpenetrating spheres at high temperatures, forming clusters, in analogy to the colloidal glass transition. In this work we demonstrate that the choice of the solvent has a dramatic effect on the gelation transition, because of the different degree of star swelling (at the same temperature) associated with the solvent quality. We construct a generic kinetic phase diagram for the gelation of different stars in different solvents (gelation temperature against effective volume fraction, phi) and propose a critical "soft sphere close packing" volume fraction phi(c) distinguishing the temperature-induced (for phiphi(c)) glass-like gelation. We conclude that appropriate selection of the solvent allows for manipulation of the sol-gel transition in such ultrasoft colloids.

ABSTRACT The offshore areas around the world are beginning to play a more significant role in meeting global energy needs. Rigs and personnel move from one part of the globe to another on a daily basis. There is growing interest in the use of standards to both enhance safety and environmental performance and to lower costs. An example of this is the increased interest in the activities of the International Organization for Standardization, and specifically ISO Technical Committee 67. ISO/TC67 is charged with preparing standards for materials and equipment, and offshore structures for the petroleum and natural gas industries. This committee has over 1,000 industry personnel working on over 130 standards. These standards define the technical operations and limits for pipe-both steel and aluminum, drilling fluids, cements and hydraulic fluids, drilling and production equipment including drill stem, packers and subsea production systems, OCTG, offshore piping, steam turbines and flexible couplings, compressors and turbines, and offshore structures including fixed steel or concrete, and floating systems. Specifically excluded from the remit for ISO/TC67 is any standardization of ships or marine technology covered by IMO, SOLAS and MARPOL. Regulatory bodies in countries must write operating practices which address their safety and environmental requirements, including the protection of personnel. It is also becoming more important that these requirements are accomplished in a cost efficient manner since companies have alternative investment opportunities due to increased access around the globe. The use of standards to which both government and industry have contributed, provides an opportunity for government to express its requirements that reflects an industry consensus on what is the best way to accomplish a task. International standards give the industry the ability to expedite manufacture and purchase of equipment, eliminating barriers to trade and commerce. Standards can also apply to less tangible items such as training and management systems. These same international standards allow regulatory agencies to apply a consistent nondiscriminatory basis for allowing industry to operate in their locale, i.e., provide a level playing field. INTRODUCTION The petroleum and natural gas industries have been vigorously pursuing the writing and adoption of international standards for about ten years. The historical perspective was presented in several papers given during former OTC meetings. 1,2,3,4, 5 Also defined in these papers are the operational aspects of each standards organization (ISO, CEN, ANSI, API, ASME, ASTM, etc.) and the interrelationships among them. This paper shows the progress made since the last paper was written (1995), and how the petroleum and natural gas is "an industry in transition" one which relies on national standards to one in which international standards represent the basis against which business is undertaken. Engaged in the transition process are oil and gas companies, manufacturers, suppliers/service companies, academia, and government bodies..

In Kluyveromyces lactis, the cell wall compositions of Kl (ATCC 96897), a wild sensitive strain, and Klm (ATCC 96896), a strain resistant to amphotericin B (AmB), were shown to be very different, since the walls in the latter were significantly enriched in hexosamine, but had a reduced content in phosphate and amino acid. In both strains, the cell walls limited their sensitivity to this antifungal agent. The absence of cell wall increased the sensitivity of the cells to this polyene by 5 to 10-fold. When the cells were treated with enzymes such as pronase and chitinase in order to change the cell wall structure just before inoculation, the yeasts appeared more resistant to the antibiotic. However, treatments with chymopapain and phospholipase C did not significantly change the sensitivity of the two strains to this agent. Cells treated with acid phosphatase displayed a longer lag phase than the control cells. In addition, when cultured in the presence of AmB, the cells were less sensitive to this agent. The present results reveal that both a change in the ionic charges of the cell wall and an alteration in the cell wall structure modified the sensitivity of these yeast strains to AmB.

The Petroleum Institute of Tatarstan has developed a special method of enhanced recovery based on the injection of ethers of cellulose mixture in order to increase the recovery of oil in water invaded hydrocarbon fields. This method creates a high viscous fringe in the formation. The purpose of this paper is to present the method, the results we got during our five years operation and the special and unique injection units which were invented to automatically perform the injection of this ecolologically pure hydroxyethylcellulose in a dispersed manner. Our area of operation is the ROMASHKINO field, situated in the Republic of Tatarstan, of the Federation of Russia. More than 3 500 tons of HEC were injected in more than 180 injection wells. The additional oil production already produced reached 1 000 000 tons and is still continuing. A goal of our efficiency of almost 400 t/t which was initially calculated has already been reached and overcome in some areas. In order to reach this result, TATOLPETRO, created some specialised trailer mounted injection units. Four trailers (pumping injection - cellulose mixing and control - power generation and utilities - bulk powder) easily moved from an injection well to another, in a very harsh environment, form the system. Its main feature is to be able to optimise the flowrate of the injection when arriving on a well and then to automatically find out the proper maximum possible dosing rate allowed by the state of the formation as well as the safety of the well structure itself. An other original feature is the low viscosity Vortex mixing chamber which disperses the cellulose in the water flow in order that the mixture reaches the formation before its comlete hydratation.

We demonstrate the reversible optical recording of holographic gratings in nonabsorbing solutions of common homopolymers. These phase gratings exhibit first-order diffraction efficiencies in excess of 50%. They are associated with the spatial modulation of the concentration of the polymer solute initiated, but not solely caused, by radiation forces.

Les stenoses et occlusions carotidiennes (essentiellement bifurcation carotidienne et origine de la carotide interne) sont en cause dans environ 8 % des AVC ( 10 % des AVC ischemiques). Plaques et stenoses carotidiennes sont de puissants marqueurs de coronaropathie (5 a 10 % seulement des patients porteurs de stenose carotidienne serree « chirurgicale » ont une coronaro-graphie normale, Hertzer 1985). Une stenose carotidienne (SC) est quantifiee par la reduction de calibre au maximum de la SC en rapportant le plus petit diametre luminal au diametre theorique du bulbe carotidien (mode ECST) ou au diametre regulier de la carotide en aval (mode NASCET). Les SC sont eligibles comme symptomatiques en cas de deficit hemispherique focalise ou de cecite mono-oculaire transitoire homolateral a la stenose et datant de moins de 4 a 6 mois. Elles sont considerees comme asymptomatiques dans tous les autres cas de figure. Face a une SC symptomatique, la cure chirurgicale de la stenose associee au traitement medical est, vs traitement medical seul, deletere pour les plaques 70 % NASCET (NNT 9) a l’exception des stenoses pseudo-occlusives (SC se comportant comme une occlusion ACI). Face a une SC asymptomatique, une indication operatoire visant a proteger d’un AVC ischemique homolateral ne se discute qu’en cas de SC > 60 % NASCET pour un benefice bien modeste en terme de reduction absolue du risque d’AVC (NNT 85). Une recherche, visant a definir des criteres de SC a sur-risque neurovasculaire, est en cours. L’angioplastie n’est pas encore une alternative a la chirurgie formellement validee. Tout patient porteur d’une SC, symptomatique ou asymptomatique, doit beneficier d’un traitement antiagregant plaquettaire.

We demonstrate a method to increase the sensitivity of the s-p phase shift under total internal reflection (TIR) for optical sensing. This is achieved by the introduction of two simple dielectric layers to the TIR surface of a fused silica prism. The enhanced sensitivity is demonstrated using evanescent-wave cavity-ring-down-ellipsometry by measuring the refractive index of liquid mixtures and by studying the adsorption of polymers to the TIR surface of the fused silica prism.

We monitor the adsorption of Rhodamine 800, and the sedimentation of a polytetrafluoroethylene (PTFE) suspension at the surface of a fused-silica prism, by measuring both the absorption and s-p phase shift Δ of a 740 nm probe laser beam, using evanescent-wave cavity ringdown ellipsometry (EW-CRDE). The two systems demonstrate the complementary strengths of EW-CRDE, as the progress of adsorption of the Rhodamine 800 dye can only be observed sensitively via the measurement of absorption, whereas the progress of sedimentation of PTFE can only be observed sensitively via the measurement of Δ. We show that EW-CRDE provides a sensitive method for the measurement of Δ and demonstrates precision in Δ of about 10(-4) deg.

EXECUTIVE SUMMARY A single global market for procurement is of crucial importance to the E&P industry. The resulting benefits, including cost reductions and shelter delivery times, could even be the key to the economic development of marginal fields. International Standards that cater for the needs of users, manufacturers and the public at large can provide a common basis for companies to procure and provide goods and services that will deliver the required performance throughout the field life. The savings to industry could be billions of dollars per year. The Oil Industry International Exploration and Production Forum (E&P Forum) and the American Petroleum Institute (API) acted as the catalyst for the re-formation of ISO TCG7 "Materials, equipment and offshore structures for petroleum and natural gas industries". The initial work was on the development of "fast track" ISO standards based on the widely accepted and used API standards. In the five years of conceited effort by the E&P industry 17 fast track standards have been published and a further 10 ISO standards have reached or passed the balloting stage and are about to be published. This process has also resulted in the development of a management procedure for the selection, processing and maintenance of standards for the E&P industry. The E&P Forum, on behalf of the industry, has developed proposals to increase the efficiency of this managerial procedure and to speed up the "internationalization" of selected standl.1rds. Details are given at the end of the paper. It is argued that the E&P industry should rally to the cause of international standardization. Companies should lend their full Support by committing their valuable expel resources. It is in the interests of the industry to do this for, without suitably skilled expel representation in ISO and the elimination of duplication as well as waste of resources through perfom1ing similar workat company or national level, the large potential benefits of international standardization will elude the E&P industry. The overall thrust may be neatly summarized by the adage:do it oncedo it rightdo it globally INTRODUCTION The E&P Forum has taken a leading role in encouraging and facilitating the internationalization of oil and gas industries standards in the area of upstream exploration and production. The need for standards became evidet1t to the expanding industry in the early 1920's. In the United States, the manufacturing industry began supplying oil field equipment not only for local developments but across the continent. The requirement for equipment to be safe and compatible was essential for obvious reasons. The need to be fit for purpose followed swiftly as production facilities became more sophisticated and fields with higher and higher pressures were developed. The American Petroleum Institute was formed, and in 1923 adopted the remit to provide the industry with standards for manufacturers equipment for use throughout the USA. At the same time, oil field development was expanding rapidly in other parts of the world, driven largely by American based companies who, naturally enough, purchased equipment from home sources according to API standards.

We report on the versatile effect of weak red laser light impinging on diblock copolymer [poly(isoprene-b-styrene)] dispersions in two selective solvents for each block. In the strongly scattering but transparent micellar solutions in hexane (a good solvent for polyisoprene), higher refractive index copolymer-rich fibers were formed. In the turbid dispersions of the same copolymer in ethyl acetate (a good solvent for polystyrene), the effect of self-induced transparency was observed. A two-step patterning mechanism caused the generation of a transparent microchannel, increasing light transmission. The analogy between the current effect and that observed in homopolymer polyisoprene solutions in different solvents is discussed toward an understanding of the unanticipated light-soft-matter interaction.

Highly c-axis-oriented thin films of α-(BEDT-TTF)2I3 have been prepared by physical vapour deposition. Structural and morphological characterization are performed by X-ray diffraction and scanning electron microscopy. In situ photoemission experiments on the films reveal five distinct features in the valence-band regime; the two structures with the lowest binding energies are assigned to molecular orbitals present in the TTF backbone. None of the valence-band structures shows dispersion along the Γ-Z(k2) direction. The spectral intensity is zero at, and to within 0.5 eV of the Fermi level. Core-level spectroscopy on the I 4d level indicates that all iodine is present as I3-ions and that the surface consists of BEDT-TTF molecules.

The deposition of Cs on c-axis-oriented thin films of α-(BEDT-TTF)2I3 causes a shift of the chemical potential in agreement with addition of electrons to the system. At high Cs doses a chemical reaction between Cs+ and I3- occurs, with the formation of CsI and probably mainly I2. In the valence-band regime new structures appear, due to I- ,i.e, CsI, and molecular orbitals of I2 derived from I 5p. The hybridization between these orbitals and the BEDT-TTF orbitals is negligible. The remarkable changes in the I 4d spectrum caused by Cs deposition can be understood within the framework of the proposed chemical reaction.