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Sample records for liquids hydroformylation des

  1. Investigation of the Hydroformylation of Ethylene in Liquid Carbon Dioxide

    SciTech Connect

    Yonker, Clement R. ); Linehan, John C. )

    2001-12-01

    In-situ, high-pressure NMR was used to investigate the hydroformylation reaction of ethylene in liquid CO2 using Rh(CO)2acac as the catalyst precursor and (p-CF3C6H4)3P, tris(p-trifluoromethylphenyl)phosphine, as the ligand under different thermodynamic conditions (T= 10? 23?C, PCO= PH2= 10? 15 bar, PC2H4= 10? 15 bar, PCO2= 207 bar). 1H NMR was used to monitor the reaction progress of the hydroformylation of ethylene with a rhodium catalyst under select conditions of temperature and CO2 solvent pressure. Potential resting states of the rhodium catalyst were investigated by 31P(1H) NMR. This is the first description of a rhodium catalyzed hydroformylation reaction in liquid CO2 monitored in-situ by high pressure NMR

  2. Hydroformylation process

    SciTech Connect

    Johnson, T.H.

    1986-04-22

    This patent describes a process for the hydroformylation of an olefin oligomerization product obtained by the liquid phase oligomerization of propylene and/or butylene in the presence of a catalyst formed by reacting a nickel compound with a hydrocarbyl aluminum halide. The hydroformylation is carried out by contacting the oligomerization product with syngas in the presence of a hydroformylation catalyst to produce aldehydes or alcohols, the improvement which comprises: contacting at a temperature ranging from about 25/sup 0/C to about 300/sup 0/C least a portion of the oligomerization product with a reforming catalyst comprising pentavalent tantalum, halogen, oxygen and an inorganic oxide substrate wherein at least one valence of tantalum is bound to oxygen which is bound to the substrate, at least one valence of the tantalum is bound to halogen and the remaining tantalum valences are bound to halogen and/or oxygen which oxygen may or may not be bound to the substrate, and then hydroformylating the resultant olefin product to produce an alcohol or aldehyde.

  3. Supercritical hydroformylations

    SciTech Connect

    Rathke, J.W.; Klingler, R.J.

    1995-12-01

    The cobalt carbonyl catalyzed hydroformylation of propylene and related equilibrium and dynamic processes were investigated by means of high-pressure NMR spectroscopy with supercritical carbon dioxide as the reaction medium. Parameters measured in CO{sub 2} include: (1) the steady-state concentrations of the catalytic intermediates, (2) the thermodynamics and forward and reverse rate constants for the hydrogention of Co{sub 2}(CO){sub 8}, and (3) the net rate and product selectivity for the overall hydroformylation reaction. The results for the various measurements in the supercritical medium will be compared with literature values for conventional liquid solvents. Evidence for the presence of the radical, {center_dot}Co(CO){sub 4}, under hydroformylation conditions, and for a promotional effect of an added stable radical, {center_dot}V(CO){sub 6}, will also be presented. NMR spectral effects associated with the use of supercritical media, the use of toroid coils and cavities in high-pressure NMR probes, and a new toroid-cavity-imaging device will be described.

  4. Reactivation of hydroformylation catalysts

    SciTech Connect

    Babin, J.E.; Bryant, D.R.; Harrison, A.M.; Miller, D.J.

    1993-08-17

    A process is described for improving the catalytic activity of a partially deactivated solubilized rhodium-tertiary organophosphine complex hydroformylation catalyst, which comprises (1) mixing under non-hydroformylating conditions, a organic liquid medium containing said solubilized partially deactivated complex catalyst, with propargyl alcohol and a carboxylic acid of the formula RCOOH wherein R represents hydrogen or an alkyl or aryl radical to obtain a treated solubilized rhodium-tertiary organophosphine complex product solution; and (2) removing from said product solution, the carboxylic acid employed in Step (1) to obtain a rhodium-tertiary organophosphine complex hydroformylation catalyst that is more catalytically active than said partially deactivated rhodium-tertiary organophosphine complex hydroformylation catalyst starting material of Step (1).

  5. Continuous flow hydroformylation using supported ionic liquid phase catalysts with carbon dioxide as a carrier.

    PubMed

    Hintermair, Ulrich; Gong, Zenxing; Serbanovic, Ana; Muldoon, Mark J; Santini, Catherine C; Cole-Hamilton, David J

    2010-09-28

    A supported ionic liquid phase (SILP) catalyst prepared from [PrMIM][Ph(2)P(3-C(6)H(4)SO(3))] (PrMIM = 1-propyl-3-methylimidazolium), [Rh(CO)(2)(acac)] (acacH = 2,4-pentanedione) [OctMIM]NTf(2) (OctMIM = 1-n-octyl-3-methylimidazolium, Tf = CF(3)SO(2)) and microporous silica has been used for the continuous flow hydroformylation of 1-octene in the presence of compressed CO(2). Statistical experimental design was used to show that the reaction rate is neither much affected by the film thickness (IL loading) nor by the syngas:substrate ratio. However, a factor-dependent interaction between the syngas:substrate ratio and film thickness on the reaction rate was revealed. Increasing the substrate flow led to increased reaction rates but lower overall yields. One of the most important parameters proved to be the phase behaviour of the mobile phase, which was studied by varying the reaction pressure. At low CO(2) pressures or when N(2) was used instead of CO(2) rates were low because of poor gas diffusion to the catalytic sites in the SILP. Furthermore, leaching of IL and Rh was high because the substrate is liquid and the IL had been designed to dissolve in it. As the CO(2) pressure was increased, the reaction rate increased and the IL and Rh leaching were reduced, because an expanded liquid phase developed. Due to its lower viscosity the expanded liquid allows better transport of gases to the catalyst and is a poorer solvent for the IL and the catalyst because of its reduced polarity. Above 100 bar (close to the transition to a single phase at 106 bar), the rate of reaction dropped again with increasing pressure because the flowing phase becomes a better and better solvent for the alkene, reducing its partitioning into the IL film. Under optimised conditions, the catalyst was shown to be stable over at least 40 h of continuous catalysis with a steady state turnover frequency (TOF, mol product (mol Rh)(-1)) of 500 h(-1) at low Rh leaching (0.2 ppm). The selectivity of the catalyst was not much affected by the variation of process parameters. The linear:branched (l:b) ratios were ca. 3, similar to that obtained using the very same catalyst in conventional organic solvents. PMID:20520868

  6. A novel dicationic phenoxaphosphino-modified Xantphos-type ligand: a ligand for highly active and selective, biphasic, rhodium catalysed hydroformylation in ionic liquids.

    PubMed

    Bronger, Raymond P J; Silva, Silvana M; Kamer, Paul C J; van Leeuwen, Piet W N M

    2004-05-21

    A highly active and regioselective catalyst obtained from a novel dicationic ligand (1) and Rh(CO)2(acac) for hydroformylation of 1-hexene and 1-octene in ionic liquids is reported. Optimisation studies of various reaction parameters led to an unprecedentedly active (TOFs > 6200 mol mol(-1) h(-1), T= 100 degrees C), selective (l/b ratios > 40) and stable hydroformylation procedure. No catalyst leaching (Rh-loss < 0.07% of initial rhodium intake, P-loss < 0.4% of the initial phosphorus intake) or losses in performance could be measured during 1-octene hydroformylation recycle experiments in 1-butyl-3-methylimidazolium hexafluorophosphate. At low catalyst loadings activities and regioselectivities competitive with one-phase catalysis in conventional solvents were observed. At high catalyst loadings the system is extremely stable and has a long shelf-life as a result of the formation of stable, if inactive rhodium dimers. PMID:15252608

  7. Gas phase hydroformylation of propylene and allyl alcohol with immobilized rhodium complexes

    SciTech Connect

    Munck, N.A.D.

    1980-01-01

    Contents: Introduction--(Carbon monoxide as a chemical feedstock, hydroformylation of alkenes, immobilization of homogeneous catalysts, synthesis of 1,4-butanediol, and scope of this thesis); Gas phase hydroformylation of propylene with porous resin anchored rhodium complexes--(Methods of catalyst preparation and characterization); Gas phase hydroformylation of propylene with porous resin anchored rhodium complexes--(The catalytic performance); Gas phase hydroformylation of propylene with immobilized rhodium complex monolayer catalysts; Gas phase hydroformylation of allyl alcohol with supported liquid phase catalysts.

  8. Asymmetric hydroformylation.

    PubMed

    Perandones, Bernabé F; Godard, Cyril; Claver, Carmen

    2013-01-01

    Rhodium is currently the metal of choice to achieve high enantioselectivities in the hydroformylation of a relatively wide variety of alkene substrates. The elucidation of the different steps of the catalytic cycle and the characterization of the resting state, together with the discovery of several types of ligands that are able to provide high enantioselectivities, have made the rhodium-catalyzed hydroformylation a synthetically useful tool. For years, ligands containing phosphite moieties such as diphosphites and phosphine-phosphites were considered the most successful ligands to achieve high enantioselectivities for classical substrates such as styrene and vinyl acetate. In fact, the phosphite-phosphine BINAPHOS (43) and its derivatives are still today the most successful ligands in terms of selectivity and scope. For more substituted substrates, general trends can be extracted. However, recent studies showed that these general trends can be sometimes reversed by the use of the appropriate catalyst and choice of reaction conditions, clearly showing that these trends are only indicative and that there are still many challenges to be tackled in this area. PMID:23595364

  9. Olefin hydroformylation

    SciTech Connect

    Hanes, R.M.

    1986-12-30

    This patent describes a process for the hydroformylation of olefins for the preparation of aldehydes, by reacting carbon monoxide and hydrogen with an olefin. This is done in the presence of an ionic metal complex catalyst where the ionic charge is on either the metal or on a ligand, at a temperature in the range of between about 80/sup 0/ and about 300/sup 0/C, and a pressure in the range of between about 400 and about 2000 psig. The improvement described here comprises performing the reaction in a polar solvent selected from the group consisting of N-substituted amide, glycols, polyglycols, mono lower alkyl ethers of glycols, dimethyl sulfoxide and sulfolane and recovering the aldehyde by extraction with a hydrocarbon solvent.

  10. Rhodium complexes stabilized by phosphine-functionalized phosphonium ionic liquids used as higher alkene hydroformylation catalysts: influence of the phosphonium headgroup on catalytic activity.

    PubMed

    Luska, Kylie L; Demmans, Karl Z; Stratton, Samantha A; Moores, Audrey

    2012-11-21

    Monodentate phosphine-functionalized phosphonium ionic liquids (PFILs) were employed as ligands for Rh complexes and used in the hydroformylation of higher alkenes. Three PFILs were designed by varying the length of the P-alkyl chain attached to the phosphonium moiety, for alkyl = methyl (1), butyl (2), octyl (3), in order to tune their solubility properties. In all PFILs, the phosphonium unit is linked to a diphenylphosphino functionality by an undecyl linker, with bis(trifluoromethylsulfonyl)imide as counter anion. These PFILs were combined with a Rh(I) precursor, [Rh(acac)(CO)(2)], to provide a biphasic hydroformylation catalyst for the transformation of 1-octene, 1-decene and 1-dodecene using tetradecyltributylphosphonium bis(trifluoromethylsulfonyl)imide, [P(4,4,4,14)]NTf(2) as a solvent. Good activities and excellent selectivities were obtained for these PFILs-Rh(I) complexes. Variation of the P-alkyl length in the PFIL ligand influenced the stability, catalytic activity and selectivity of the PFIL-stabilized catalyst. PMID:23023783

  11. Rhodium catalyzed hydroformylation of internal olefins

    SciTech Connect

    Young, D.A.

    1986-11-25

    This patent describes a process for hydroformylation of an internal olefin selected from the group consisting of aliphatic olefins, cycloaliphatic olefins, and substituted derivatives thereof wherein the substituent comprises alkyl, aryl, alkaryl, aralkyl, cycloalkyl, hydroxy, -CHO and -C(O)OX, where X is alkyl of 1 to 20 carbon atoms in a hydroformylation reaction zone in the presence of a liquid rhodium triorgano phosphine catalyst system and in the presence of carbon monoxide and hydrogen to form the corresponding aldehydes. The improvement described here comprises employing in the the reaction zone at least one sterically hindered tricycloalkylphosphine.

  12. Rhodium hydroformylation mechanisms

    SciTech Connect

    Oswald, A.A.; Hendriksen, D.E.; Kastrup, R.V.; Merola, J.S.

    1982-03-01

    While the first 25 years of hydroformylation, i.e. oxo-process, chemistry were dominated by cobalt based catalysts, there has been rapid development of rhodium complex hydroformylation catalysts during the last 10 years. Although rhodium is about 100 times more expensive than cobalt, the low pressure activity of some rhodium complex catalysts is highly attractive when compared with the high pressure activity of the main cobalt catalyst, i.e., cobalt tetracarbonyl hydride. As a consequence, new plants for the selective hydroformylation of propylene to n-butyraldehyde, a key intermediate in the production of diethylhexyl phthalate plasticizer, have been for the most part based on a triphenylphosphine (Ph/sub 3/P) rhodium complex catalyst system, jointly developed by Union Carbide Corporation and Davy McKee Ltd. The mechanism of this catalyst system, which is presently of paramount importance in rhodium hydroformylation, is the main topic of the present paper.

  13. Evolution of hydroformylation chemistry

    SciTech Connect

    Slaugh, L.H.

    1995-12-01

    A new generation of hydroformylation catalysts was discovered in 1960 at Shell Development Company which dramatically altered the chemistry of producing industrially important alcohols from synthesis gas (CO/H{sub 2}) and olefins. These new homogeneous catalysts were obtained via the use of auxiliary tertiary phosphine ligands with the conventional OXO cobalt carbonyl catalyst. This is believed to have been the first historical example illustrating the utility of phosphine ligands to modify the catalytic properties of homogenous catalysts. In contradistinction to the conventional OXO reaction, highly linear alcohols were obtained in a single-step operation with ease of catalyst recycle. Based on this discovery, an industrial process was developed to produce large volume, environmentally friendly detergent alcohols. The chemistry of this process and a comparison with other hydroformylation catalyst systems will be made. Recent results obtained with phosphine-modified cobalt catalysts for the hydroformylation of substrates other than olefins will be presented.

  14. Advances in hydroformylation catalysis

    SciTech Connect

    Oswald, A.A.; Kastrup, R.V.; Mozeleski, E.J.

    1987-04-01

    Hydroformylation is a key reaction in petrochemical technology for the conversion of olefins to aldehyde intermediates via reaction with synthesis gas: e.g., RCH = CH{sub 2} + CO + H{sub 2} {yields} RCH{sub 2}CH{sub 2}CHO + RCH(CH{sub 3})CHO. The reaction is catalyzed by Group VIII transition metal carbonyl hydrides, in general, but its petrochemical use is limited to cobalt and rhodium catalysts. The reaction, commonly known in the industry as the oxo-process, was discovered with cobalt in the 1940's but most of the advances were made with rhodium during the last 20 years. In the present overview, at first the significance of the reaction will be reviewed. Thereafter, basic concepts of hydroformylation catalysis will be discussed, largely on the basis of studies we carried out at Exxon. In cobalt catalysis, studies of concurrent isomerization hydroformylation will be presented. A major part of the presentation will focus on developments in rhodium hydroformylation and the steric effects of phosphine ligands on the formation of rhodium catalyst complexes of different structures under CO/H{sub 2} pressure.

  15. Cobalt carbonyl catalyzed olefin hydroformylation in supercritical carbon dioxide

    SciTech Connect

    Rathke, J.W.; Klingler, R.J.

    1992-12-31

    A method of olefin hydroformylation is provided wherein an olefin reacts with a carbonyl catalyst and with reaction gases such as hydrogen and carbon monoxide in the presence of a supercritical reaction solvent, such as carbon dioxide. The invention provides higher yields of n-isomer product without the gas-liquid mixing rate limitation seen in conventional Oxo processes using liquid media.

  16. Cobalt carbonyl catalyzed olefin hydroformylation in supercritical carbon dioxide

    DOEpatents

    Rathke, J.W.; Klingler, R.J.

    1993-03-30

    A method of olefin hydroformylation is provided wherein an olefin reacts with a carbonyl catalyst and with reaction gases such as hydrogen and carbon monoxide in the presence of a supercritical reaction solvent, such as carbon dioxide. The invention provides higher yields of n-isomer product without the gas-liquid mixing rate limitation seen in conventional Oxo processes using liquid media.

  17. Cobalt carbonyl catalyzed olefin hydroformylation in supercritical carbon dioxide

    DOEpatents

    Rathke, Jerome W. (Lockport, IL); Klingler, Robert J. (Westmount, IL)

    1993-01-01

    A method of olefin hydroformylation is provided wherein an olefin reacts with a carbonyl catalyst and with reaction gases such as hydrogen and carbon monoxide in the presence of a supercritical reaction solvent, such as carbon dioxide. The invention provides higher yields of n-isomer product without the gas-liquid mixing rate limitation seen in conventional Oxo processes using liquid media.

  18. The Retro-Hydroformylation Reaction.

    PubMed

    Kusumoto, Shuhei; Tatsuki, Toshiumi; Nozaki, Kyoko

    2015-07-13

    Hydroformylation, a reaction that adds carbon monoxide and dihydrogen across an unsaturated carbon-carbon multiple bond, has been widely employed in the chemical industry since its discovery in 1938. In contrast, the reverse reaction, retro-hydroformylation, has seldom been studied. The retro-hydroformylation reaction of an aldehyde into an alkene and synthesis gas (a mixture of carbon monoxide and dihydrogen) in the presence of a cyclopentadienyl iridium catalyst is now reported. Aliphatic aldehydes were converted into the corresponding alkenes in up to 91% yield with concomitant release of carbon monoxide and dihydrogen. Mechanistic control experiments indicated that the reaction proceeds by retro-hydroformylation and not by a sequential decarbonylation-dehydrogenation or dehydrogenation-decarbonylation process. PMID:26089259

  19. Highly regioselective osmium-catalyzed hydroformylation.

    PubMed

    Wu, Lipeng; Liu, Qiang; Spannenberg, Anke; Jackstell, Ralf; Beller, Matthias

    2015-02-21

    The first highly regioselective and general osmium-catalyzed hydroformylation of olefins to aldehydes is reported. The combination of Os3(CO)12 and imidazoyl-substituted phosphine ligands allows n-selective (up to 99%) hydroformylation of bulk aliphatic as well as functional alkenes in good yields (64-87%). PMID:25620413

  20. Towards a Benign and Viable Rhodium Catalyzed Hydroformylation of Higher Olefins: Economic and Environmental Impact Analyses, Solvent Effects and Membrane-based Catalyst Separation

    E-print Network

    Fang, Jing

    2009-04-28

    Researchers at the Center for Environmentally Beneficial Catalysis (CEBC) had previously reported a novel rhodium-based hydroformylation process concept based on the use of CO2-expanded liquids (CXLs) to intensify rates and obtain higher linear...

  1. Method for removing hydroformylation catalyst

    SciTech Connect

    Summerlin, W.H.

    1993-08-17

    A method is described for removing Co values from the crude product of a Co-catalyzed hydroformylation reaction formed from an olefinic feedstock, which comprises: (a) contacting the crude product with a stream of oxygen containing gas, an organic acid selected from the group consisting of: formic acid, acetic acid, propionic acid, and other acids having a boiling point approximately the same as water such that appreciable values of acid can be recovered in step (d), and water thereby producing a substantially Co-free organic hydroformylation reaction product and a water soluble Co salt aqueous product; (b) separating the Co-free crude product from the water soluble Co salt aqueous product; (c) diverting the Co-free organic hydroformylation reaction product for further downstream treatment such as distillation or hydrogenation; (d) concentrating the water soluble Co salt aqueous product thereby producing a concentrated aqueous solution of Co salt and a Co-free water containing the organic acid; (e) recycling the substantially Co-free water containing the organic acid to step (a); (f) contacting the concentrated aqueous solution of Co salt with an alcohol stream and synthesis gas, and passing this mixture to a preformer reactor where the concentrated aqueous solution of Co salt is converted to a Co carbonyl; (g) contacting the Co carbonyl with a stream of stripping gas to entrain volatile Co compounds in the stripping gas and to generate as bottoms alcohol products and dissolved Co salts, whereby the entrained volatile Co compounds are taken out overhead and the alcohol products and dissolved Co salts are taken out as bottoms; (h) separating the alcohol products of step (g) from the dissolved Co salts; (i) recycling the alcohol product from step (h) to step (f); (j) recycling the dissolved Co salts from step (h) to step (a); and (k) contacting the Co compounds from step (g) with the olefinic feedstock, whereby the Co compounds are absorbed.

  2. A Hybrid Phosphorus Ligand for Highly Enantioselective Asymmetric Hydroformylation

    E-print Network

    Zhang, Xumu

    A Hybrid Phosphorus Ligand for Highly Enantioselective Asymmetric Hydroformylation Yongjun Yan enantioselectivities (up to 99% ee) have been achieved in the Rh-catalyzed asymmetric hydroformylations of styrene derivatives and vinyl acetate. Introduction Hydroformylation is the reaction of alkenes with carbon monoxide

  3. Directed Rhodium-Catalyzed Hydroformylation of Alkenes

    NASA Astrophysics Data System (ADS)

    Breit, Bernhard

    Installation of substrate-bound catalyst-directing phosphine groups allows for efficient substrate control of all aspects of reaction selectivity in the course of the industrially important hydroformylation reaction. In particular, the ortho-diphenylphosphanylbenzoyl (o-DPPB) group has proved to be a highly efficient and practical directing group for controlling regioselectivity and diastereoselectivity of a range allylic and homoallylic alcohol derivatives. A chiral variant, the o-DPPF directing group, enables a desymmetrizing hydroformylation of prochiral dialkenyl- and diallylcarbinols to give substrates with two stereocenters in enantiomerically pure form. Incorporation of the hydroformylation as part of sequential processes is possible and has led to the development of synthetically appealing multiple carbon-carbon and carbon-heteroatom bond formations.

  4. Alternative metals for homogeneous catalyzed hydroformylation reactions.

    PubMed

    Pospech, Jola; Fleischer, Ivana; Franke, Robert; Buchholz, Stefan; Beller, Matthias

    2013-03-01

    Transition-metal-catalyzed hydroformylation reactions constitute one of the most powerful tools for C-C bond formation in organic synthesis and represent an outstanding example of the application of homogeneous catalysis on an industrial scale. This process allows for the straightforward conversion of inexpensive chemical feedstock into broadly applicable aldehydes, which serve as major building blocks for numerous chemical products. These products are highly valuable for the chemical industry and used as plasticizers, detergents, and surfactants on a million ton scale. Moreover, aldehydes serve as versatile chemical intermediates for the production of fine chemicals and pharmaceuticals. Currently, most of the bulk hydroformylation processes rely on rhodium-based catalysts. The increasing demand and resulting high cost of this precious metal has resulted in alternative transition-metal catalysts becoming highly desirable. The following Review summarizes the progress achieved utilizing Ru, Ir, Pd, Pt, and Fe catalysts in hydroformylation reactions. PMID:23436281

  5. Distal-Selective Hydroformylation using Scaffolding Catalysis

    PubMed Central

    2015-01-01

    In hydroformylation, phosphorus-based directing groups have been consistently successful at placing the aldehyde on the carbon proximal to the directing group. The design and synthesis of a novel catalytic directing group are reported that promotes aldehyde formation on the carbon distal relative to the directing functionality. This scaffolding ligand, which operates through a reversible covalent bond to the substrate, has been applied to the diastereoselective hydroformylation of homoallylic alcohols to afford ?-lactones selectively. Altering the distance between the alcohol and the olefin revealed that homoallylic alcohols gives the distal lactone with the highest levels of regioselectivity. PMID:24902624

  6. Immobilized bisdiazaphospholane catalysts for asymmetric hydroformylation.

    PubMed

    Adint, Tyler T; Landis, Clark R

    2014-06-01

    Condensation reactions of enantiopure bis-3,4-diazaphospholanes (BDPs) that are functionalized with carboxylic acids enable covalent attachment to bead and silica supports. Exposure of tethered BDPs to the hydroformylation catalyst precursor, Rh(acac)(CO)2, yields catalysts for immobilized asymmetric hydroformylation (iAHF) of prochiral alkenes. Compared with homogeneous catalysts, catalysts immobilized on Tentagel resins exhibit similarly high regioselectivity and enantioselectivity. When corrected for apparent catalyst loading, the activity of the immobilized catalysts approaches that of the homogeneous analogues. Excellent recyclability with trace levels of rhodium leaching are observed in batch and flow reactor conditions. Silica-bound catalysts exhibit poorer enantioselectivities. PMID:24742285

  7. Rh-catalyzed linear hydroformylation of styrene.

    PubMed

    Boymans, Evert; Janssen, Michèle; Müller, Christian; Lutz, Martin; Vogt, Dieter

    2013-01-01

    Usually the Rh-catalyzed hydroformylation of styrene predominantly yields the branched, chiral aldehyde. An inversion of regioselectivity can be achieved using strong ?-acceptor ligands. Binaphthol-based diphosphite and bis(dipyrrolyl-phosphorodiamidite) ligands were applied in the Rh-catalyzed hydroformylation of styrene. High selectivities up to 83% of 3-phenylpropanal were obtained with 1,1-bi-2-naphthol-based bis(dipyrrolyl-phosphorodiamidite) with virtually no hydrogenation to ethyl benzene. The coordination chemistry of those ligands towards Rh(I) was investigated spectroscopically and structurally. PMID:23104326

  8. Distal-selective hydroformylation using scaffolding catalysis.

    PubMed

    Joe, Candice L; Blaisdell, Thomas P; Geoghan, Allison F; Tan, Kian L

    2014-06-18

    In hydroformylation, phosphorus-based directing groups have been consistently successful at placing the aldehyde on the carbon proximal to the directing group. The design and synthesis of a novel catalytic directing group are reported that promotes aldehyde formation on the carbon distal relative to the directing functionality. This scaffolding ligand, which operates through a reversible covalent bond to the substrate, has been applied to the diastereoselective hydroformylation of homoallylic alcohols to afford ?-lactones selectively. Altering the distance between the alcohol and the olefin revealed that homoallylic alcohols gives the distal lactone with the highest levels of regioselectivity. PMID:24902624

  9. Hydroformylation of Mixed Octenes Using RhodiumBulky Phosphonite Complexes with Excellent Catalytic Activity and Stability

    E-print Network

    Kim, Ji Man

    Hydroformylation of Mixed Octenes Using Rhodium­Bulky Phosphonite Complexes with Excellent as stability for the hydroformylation of mixed olefins, especially butene dimer. Hydroformylation products­3 It is well known that the olefin hydroformylation employs homogeneous complex catalysts such as Group VIII

  10. Supported aqueous-phase, rhodium hydroformylation catalysts: II. Hydroformylation of linear, terminal and internal olefins

    SciTech Connect

    Arhancet, J. P.; Davis, M. E.; Hanson, B. E. )

    1991-05-01

    Hydroformylation of 1-, 2-, and 3-heptene by supported aqueous-phase (SAP) catalysts shows that the conversion to aldehydes and the regioselectivity are functions of the position of the double bond. 1-Tetradecene and 1-heptadecene give results similar to 1{minus}heptene while data obtained from t-7-tetradecene compare well to those observed from t-2-heptene indicating the independence of chain length. Linear dienes are shown to be hydroformylated as well. Effects of temperature and pressure and water content are illustrated using linear, terminal, and internal olefins.

  11. Hydroformylation: An Old Yet New Industrial Route to Alcohols.

    ERIC Educational Resources Information Center

    Pruett, Roy L.

    1986-01-01

    Discusses trends in hydroformylation chemistry, considering these catalysis and ligands: (1) cobalt, (2) cobalt-phosphine, and (3) rhodium-phosphine. Indicates that rhodium technology will grow in domination of hydroformylation practice. In addition, processes adapted to special cases of functional olefins and to higher olefins can be expected.…

  12. Study of the hydroformylation of propylene trimers

    SciTech Connect

    Vigranenko, Yu.T.; Rybakov, V.A.; Khokhlova, M.V.; Fedorov, V.S.

    1988-01-10

    The effects of catalyst concentration, the partial pressure of hydrogen and carbon monoxide, and the overall pressure of the synthetic gas on the rate and selectivity of hydroformylation of C/sub 9/ olefins were studied and the hydration of the resultant C/sub 10/ aldehyde relationship was examined. It is shown that the reaction rate, when studying the effect of the partial pressure of hydrogen on the propylene trimer oxo reaction rate, was proportional to the hydrogen pressure at pressures up to 20 MPa. Partial pressure of carbon monoxide inhibited the reaction in the pressure range 6-22 MPa.

  13. Kinetic and thermodynamic analysis of the hydroformylation of isobutylene catalyzed by cobalt hydrocarbonyl

    NASA Astrophysics Data System (ADS)

    Vigranenko, Yu. T.; de Vekki, A. V.; Ushakov, V. M.

    2011-10-01

    The values of the variable component of chemical affinity ( A- A 0) are calculated and the relation between W (a kinetic parameter) and A- A 0 (a thermodynamic parameter) are established on the basis of experimental data on rates of the hydroformylation reaction ( W) of isobutylene catalyzed by cobalt hydrocarbonyl, and of data on compositions of the gas and liquid phases of the reaction mixture. The linear phenomenological relations of nonequilibrium thermodynamics are found to describe the dependence of W on A- A 0 quite well at a conversion level of isobutylene of ?50%.

  14. Platinum-catalyzed hydroformylation of terminal and internal octenes.

    PubMed

    van Duren, Ruben; van der Vlugt, Jarl Ivar; Kooijman, Huub; Spek, Anthony L; Vogt, Dieter

    2007-03-14

    A brief historic overview of Pt/Sn-catalyzed hydroformylation as well as recent advances in the hydroformylation of internal alkenes is provided. This serves as background for the results obtained with the [Pt(Sixantphos)Cl(2)] system, for which the molecular structure and the spectroscopic data are described. Insitu UV/Vis-spectroscopic studies have revealed rapid formation of the corresponding Pt-stannate complex upon reaction with SnCl(2), whereas high-pressure insitu IR-spectroscopy showed formation of a Pt-CO species and a short-lived Pt-H species under syngas, as well as rapid evolution of aldehyde product upon addition of 1-octene to the preformed catalyst in the IR autoclave. The hydroformylation of 1-octene and the i-octenes has been performed. For the internal alkenes, selective tandem isomerization/hydroformylation towards n-nonanal is observed with this catalyst system. PMID:17325781

  15. Palladium-catalyzed isomerization and hydroformylation of olefins.

    PubMed

    Jennerjahn, Reiko; Piras, Irene; Jackstell, Ralf; Franke, Robert; Wiese, Klaus-Diether; Beller, Matthias

    2009-06-22

    A novel selective palladium catalyst system based on bidentate 2,2'-heteroarylarylphosphines and p-TsOH has been developed for hydroformylation reactions (see scheme). By applying optimal conditions good to excellent regioselectivity is obtained for the hydroformylation of aliphatic and aromatic olefins. It is shown that a low acid concentration is crucial for obtaining high degrees of the linear isomer.The palladium-catalyzed hydroformylation of 1-octene has been studied in the presence of different phosphines and acid cocatalysts. The best results are achieved in the presence of in situ-generated palladium complexes with bidentate phosphines. It is demonstrated that the acid concentration is a crucial factor for obtaining high linear selectivity. A novel optimized catalyst based on an arylheteroarylphosphine has been applied for hydroformylation of different aliphatic and aromatic olefins. Good activity and excellent selectivity towards the linear aldehydes is achieved. PMID:19466732

  16. Kinetics and dynamics of heterogeneous hydroformylation Rh catalysts

    SciTech Connect

    Chuang, S.S.C.; Brundage, M.A.; Balakos, M.W.

    1995-12-01

    Carbon monoxide insertion is a key step toward the formation of higher oxygenates on hydroformylation and the Fischer-Tropsch synthesis. Steady-state isotopic transient and in situ infrared have been employed to determine the effect of partial pressure of reactants on the reactivity and the coverages of IR-observable adsorbates and reaction intermediates leading to the formation of propionaldehyde during ethylene hydroformylation on rhodium/silica.

  17. Hydroformylation catalyzed by immobilized rhodium complex to polymer support

    SciTech Connect

    Yoneda, N.; Nakagawa, Y.; Mimami, T.

    1996-10-01

    The concept of hydroformylation by immobilized rhodium complexes on solid support has received a certain amount of attention, as revealed by many literature and patents. Polymers such as styrene-divinyl benzene and inorganic compounds functionalized by phosphine or amines have been used as supports. This study reports on the use of divinylbenzene crosslinked with vinyl pyridine as the support. Three types of rhodium complexes were prepared and their properties and activities for the hydroformylation of propylene and 1-octene were studied at 100-130{degrees}C, 30-90 Kg/cm{sup 2} and H{sub 2}/CO=1. This novel catalyst has both hydroformylation activity and insignificant rhodium leaching.

  18. Modification of cobalt carbonyl hydroformylation catalysts by silylphosphine ligands

    SciTech Connect

    Kagan, Y.B.; Butkova, O.L.; Korneeva, G.A.; Loktev, S.M.

    1986-02-10

    This work determines the relationship involved in modification of Co carbonyls by bidentate ligands containing a silicon-hydrocarbon fragment in a diphosphine molecule; the work was also aimed at studying the catalytic properties of the complexes that are formed in the reaction of homogeneous hydroformylation of olefins. The methods used in synthesizing such organic silicon-phosphorus ligands are described. The authors found that the introduction of an organosilicon fragment into the hydrocarbon chain connecting the phosphorus atoms in a diphosphine does not affect the properties of this compound as a modifier of cobalt carbonyl catalyst for olefin hydroformylation.

  19. Prospects of using the process of hydroformylation with cobalt catalysts

    SciTech Connect

    Katsnel`son, M.G.; Kagna, S.Sh.; Beilin, L.B.

    1992-12-31

    On the basis of an analysis of experimental data it is concluded that the reduction in selectivity during the hydroformylation of olefins is due not to the nature of the catalyst metal, as believed previously, but to the presence in the reaction medium of its oxidized form. The basic possibility, in processes based on the use of cobalt carbonyls as the catalyst, of achieving an overall selectivity not inferior to that achieved in processes using rhodium carbonyls is shown. The catalytic activity of cations of different metals in the condensation of hydroformylation aldehydes has been studied. 5 tabs.

  20. Selective palladium-catalyzed hydroformylation of alkynes to ?,?-unsaturated aldehydes.

    PubMed

    Fang, Xianjie; Zhang, Min; Jackstell, Ralf; Beller, Matthias

    2013-04-22

    Atom-efficient: A selective palladium catalyst system is used for the hydroformylation of alkynes (see picture). In this syngas reaction, various alkynes were smoothly transformed to synthetically interesting ?,?-unsaturated aldehydes in good yields with high regio- and stereoselectivity. PMID:23520060

  1. The role of metals and ligands in organic hydroformylation.

    PubMed

    Gonsalvi, Luca; Guerriero, Antonella; Monflier, Eric; Hapiot, Frédéric; Peruzzini, Maurizio

    2013-01-01

    In this chapter the effect of transition metals and of ancillary stabilizing ligands on the activity, regioselectivity, and chemoselectivity in hydroformylation reactions applied to organic synthesis will be reviewed, highlighting recent cases of particular interest, including examples of both homogeneous and heterogeneous catalytic reactions. PMID:23571859

  2. Accessible protocol for asymmetric hydroformylation of vinylarenes using formaldehyde.

    PubMed

    Morimoto, Tsumoru; Fujii, Tetsuji; Miyoshi, Kota; Makado, Gouki; Tanimoto, Hiroki; Nishiyama, Yasuhiro; Kakiuchi, Kiyomi

    2015-04-28

    We report herein on an accessible protocol for the asymmetric hydroformylation of vinylarenes using formaldehyde as a substitute for syngas. The regioselectivity (branched/linear = up to 96/4) and enantioselectivity (up to 95% ee) can be attributed to the use of chiral Ph-bpe as a ligand. PMID:25783694

  3. Efficient synthesis of new fluorinated building blocks by means of hydroformylation.

    PubMed

    Fanfoni, Lidia; Diab, Lisa; Smejkal, Tomas; Breit, Bernhard

    2014-01-01

    Hydroformylation of fluorinated alkenes is an efficient method for the preparation of fluorinated functionalized building blocks for the synthesis of biologically active target structures. In this article we summarize known hydroformylation reactions of fluorinated olefins and we add new results from our research groups. Particular attention is paid to the remarkable influence of organofluorine substituents on catalyst activity, regio- and stereoselectivity of the hydroformylation reaction. PMID:25198747

  4. Analyse chronometrique intersexes de la resolution de la tache d'horizontalite des liquides

    NASA Astrophysics Data System (ADS)

    Berthiaume, Francois

    D'abondantes recherches ont demontre que la reussite a la tache d'horizontalite des liquides est en moyenne plus elevee chez les individus de sexe masculin que chez ceux de sexe feminin. Deux facteurs principaux ont ete proposes: il s'agit de la connaissance du principe physique de l'invariance de l'orientation des liquides et de certaines habiletes perceptives d'ordre visuel. Le but de la presente recherche est d'etablir la duree detaillee de la resolution de la tache d'horizontalite des liquides chez 185 filles et 180 garcons, ages de 15 a 19 ans et repartis en 8 groupes. Dans une version informatisee, le premier groupe trace la position de la surface de l'eau a l'interieur d'un contenant dans diverses inclinaisons et le deuxieme evalue si l'orientation d'une ligne y represente bien cette position; le troisieme groupe trace une horizontale dans un rectangle et le quatrieme juge si la ligne illustree y est bien horizontale. Quatre autres groupes executent respectivement les memes taches dans la version classique papier-crayon. Le temps accorde a la reflexion avant de commencer le trace, le temps de tracage comme tel et le temps de verification du trace complete sont calcules. Chez les groupes qui evaluent l'orientation d'une ligne sur support informatique, le temps requis pour y parvenir est note. Enfin, un questionnaire estime si les participants connaissent ou non le principe physique d'invariance de l'orientation de la surface d'un liquide. Les resultats revelent que cette connaissance est plus frequente chez les garcons dans l'ensemble des groupes. Dans le cas ou les sujets ont a tracer une ligne, les filles reussissent moins d'essais que les garcons s'il faut, sur support informatique, tracer la surface de l'eau dans un contenant incline ou a l'horizontale. Il en va de meme s'il faut, sur support papier, tracer une horizontale dans un contenant incline. Le trace de la surface de l'eau est plus exact chez les sujets connaissant le principe d'invariance et l'ecart intersexes disparait si l'analyse tient compte de cette connaissance. Sur le plan du temps de reponse, les deux sexes ne se distinguent que lors du trace de la surface de l'eau dans un contenant incline, les garcons reflechissant alors plus longtemps. Le temps mis a produire, puis a verifier un trace, ne differe pas selon le sexe des participants. Dans l'evaluation de l'orientation d'une ligne cependant, les filles ne se distinguent pas des garcons et les participants connaissant le principe d'invariance reussissent mieux que ceux l'ignorant. Par ailleurs, les filles procedent toujours moins rapidement que les garcons. Pour les contenants inclines ou a l'horizontale, si la ligne represente la surface de l'eau, la difference intersexes est annulee quand la connaissance du principe est prise en compte. (Abstract shortened by UMI.)

  5. Application de la topologie moléculaire à la prédiction de la viscosité liquide des composés organiques

    NASA Astrophysics Data System (ADS)

    García-Domenech, R.; Villanueva, A.; Gálvez, J.; Gozalbes, R.

    1999-07-01

    Molecular Topology has been applied to search for a mathematical model able to predict liquid viscosity values for an extensive group of organic compounds with C, H, O, N, S and halogenous atoms. The topological descriptors we have used are the connectivity indices from Kier et Hall -up to fourth order-, and the electrotopological indices. Quality of regression equation finally selected has been evaluated by a crossvalidation study. Viscosity of all compounds excepted 1,1,2-trichlorotrifluoro etane is correctly predicted by the model proposed. Nous avons appliqué la topologie moléculaire à la recherche d'un modèle mathématique capable de prédire la viscosité liquide d'un large groupe de composés organiques contenant C, H, O, N, S et des halogènes. Les descripteurs topologiques utilisés pour cette étude des relations quantitatives structure-propiété, R.Q.S.P., sont les indices de connectivité de Kier et Hall -jusqu'à l'ordre quatre- ainsi que les indices atomiques électrotopologiques. La qualité de l'équation de régression multilinéaire obtenue (aussi dite “fonction de connectivité") a été évaluée par une étude de validation croisée. Tous les composés excepté le 1,1,2-trichlorotrifluoréthane s'ajustent au modèle proposé.

  6. Rhodium-catalyzed hydroformylation in fused azapolycycles synthesis.

    PubMed

    Settambolo, Roberta

    2013-01-01

    N-Heterocycles, including fused ones, have proven to be an important class of compounds since they possess biological and pharmacological activities themselves and serve as valuable intermediates for synthetic drug discovery. My interest in the synthesis of these compounds stems from studies dealing with the hydroformylation (oxo) of olefins. The dihydroindolizines and benzofused ones are easily generated via rhodium-catalyzed hydroformylation of N-allylpyrroles and indoles: the butanal intermediate undergoes an intramolecular cyclodehydration giving the final polycyclic compound. This chapter reports my results in the area of the conversions of oxo aldehydes with additional C,C-bond-forming reactions together with relevant work from other laboratories on additional C,N-bond-forming reactions, encountered in the field of Azapolycycles synthesis over the last 5 years or so. The intramolecular sequences for polycylization will be especially emphasized using rhodium complexes to effect these transformations, under both conventional and microwave heating. PMID:23609320

  7. Computational kinetics of cobalt-catalyzed alkene hydroformylation.

    PubMed

    Rush, Laura E; Pringle, Paul G; Harvey, Jeremy N

    2014-08-11

    Density functional theory, coupled-cluster theory, and transition state theory are used to build a computational model of the kinetics of phosphine-free cobalt-catalyzed hydroformylation and hydrogenation of alkenes. The model provides very good agreement with experiment, and enables the factors that determine the selectivity and rate of catalysis to be determined. The turnover rate is mainly determined by the alkene coordination step. PMID:24700408

  8. Towards the development of a selective ruthenium-catalyzed hydroformylation of olefins.

    PubMed

    Fleischer, Ivana; Wu, Lipeng; Profir, Irina; Jackstell, Ralf; Franke, Robert; Beller, Matthias

    2013-08-01

    The ruthenium-catalyzed hydroformylation of 1- and 2-octene to give preferentially the corresponding linear aldehyde is reported. The catalyst system comprising of Ru3 (CO)12 and an imidazole-substituted monophosphine ligand allows for high chemo- and regioselectivity. The hydroformylation proceeds with unprecedented rates for a ruthenium-based catalyst. PMID:23828402

  9. In situ spectroscopic studies in hydroformylation of olefins

    SciTech Connect

    Horvath, I.T.

    1995-12-01

    Since most hydroformylation (or oxo) processes are performed above atmospheric pressure, high pressure IR and NMR have been extensively for mechanistic studies. The initial goal of these studies is to develop a molecular snapshot of reactions which are part of or connected to the catalytic cycle. A generalized catalytic cycle and relevant spectroscopic opportunities will be described. The in situ spectroscopic data combined with other mechanistic information could lead to the design of novel catalyst system(s) targeting strict process requirements. The application of in situ IR and/or NMR will be demonstrated for cobalt and rhodium based catalyst systems modified by various phosphines.

  10. Chemical transformations during rectification of products of hydroformylation of propylene

    SciTech Connect

    Kuz'mina, L.S.; Maiorova, L.V.; Kharisov, M.A.

    1988-09-10

    The occurrence of reactions related to losses of the target products, aldehydes and alcohols, was established in continuous rectification of the products of hydroformylation of propylene. The sections of the zone of primary occurrence of the reactions of aldol condensation, formation of acetals, and esterification of butyl alcohols with butyric acids were determined in the rectification column. It was shown that with increase in temperature in the rectification column still the degree of aldehyde and alcohol conversion in the overall rectification system decreases with respect to aldol condensation and acetal formation, while increasing with respect to alcohol esterification.

  11. Supramolecularly Regulated Ligands for Asymmetric Hydroformylations and Hydrogenations.

    PubMed

    Vidal-Ferran, Anton; Mon, Ignasi; Bauzá, Antonio; Frontera, Antonio; Rovira, Laura

    2015-08-01

    Herein we report the use of polyether binders as regulation agents (RAs) to enhance the enantioselectivity of rhodium-catalyzed transformations. For reactions of diverse substrates mediated by rhodium complexes of the ?,?-bisphosphite-polyether ligands 1-5,a-d, the enantiomeric excess (ee) of hydroformylations was increased by up to 82?% (substrate: vinyl benzoate, 96?%?ee), and the ee value of hydrogenations was increased by up to 5?% (substrate: N-(1-(naphthalene-1-yl)vinyl)acetamide, 78?%?ee). The ligand design enabled the regulation of enantioselectivity by generation of an array of catalysts that simultaneously preserve the advantages of a privileged structure in asymmetric catalysis and offer geometrically close catalytic sites. The highest enantioselectivities in the hydroformylation of vinyl acetate with ligand 4?b were achieved by using the Rb[B(3,5-(CF3)2 C6 H3)4] (RbBArF) as the RA. The enantioselective hydrogenation of the substrates 10 required the rhodium catalysts derived from bisphosphites 3?a or 4?a, either alone or in combination with different RAs (sodium, cesium, or (R,R)-bis(1-phenylethyl)ammonium salts). This design approach was supported by results from computational studies. PMID:26119347

  12. Novel synthesis of modified tetraphosphine ligands for bimetallic hydroformylation catalysis

    SciTech Connect

    Koch, H.F.; Misquitta, B.J.; Stanley, G.G.

    1996-10-01

    Bimetallic rhodium complexes based on the novel binucleating tatraphosphine ligand system racemic-Et{sub 2}PCH{sub 2}CH{sub 2}P(Ph)CH{sub 2}P(Ph)CH{sub 2}CH{sub 2}PEt{sub 2}, et,ph-P4, are highly active and selective hydroformylation catalysts that make use of bimetallic cooperativity to operate. The versatility of the previously reported hydroformylation ligand (et,ph-P4) has been expanded by changing the substituents on the internal phosphorus atoms. This was made possible by the ability to synthesize a variety of substituted methylene bridges of the type (H)RPCH{sub 2}PR(H). These were made by employing a new Grignard-like synthesis with bis(dichlorophosphine)methane (Cl{sub 2}PCH{sub 2}PCl{sub 2}). This new Grignard-like chemistry has also allowed us to synthesize, cleanly and quantitatively, previously unattainable disubstituted alkyl phosphines of the type P(H)R{sub 2} and P(Cl)R{sub 2}.

  13. Features of hydroformylation in the presence of a rhodium complex with a macromolecular phosphine ligand

    SciTech Connect

    Imyanitov, N.S.; Tupitsyn, S.B.

    1993-12-31

    In the present paper a quantitative comparison is made of the catalytic activity and regioselectivity in 1-dodecene hydroformylation of complexes of rhodium with triphenylphosphine and with phosphinated polystyrene dissolved in the reaction medium. 22 refs., 4 figs., 2 tabs.

  14. Rhodium/phospholane-phosphite catalysts give unusually high regioselectivity in the enantioselective hydroformylation of vinyl arenes.

    PubMed

    Noonan, Gary M; Cobley, Christopher J; Mahoney, Thomas; Clarke, Matthew L

    2014-02-11

    Using the phospholane-phosphite ligand, BOBPHOS, almost perfect regioselectivities and high enantioselectivities (up to 92% ee) are observed in Rh catalysed enantioselective hydroformylation of vinyl arenes. This can be achieved under solvent-free conditions. PMID:24362887

  15. Confining phosphanes derived from cyclodextrins for efficient regio- and enantioselective hydroformylation.

    PubMed

    Jouffroy, Matthieu; Gramage-Doria, Rafael; Armspach, Dominique; Sémeril, David; Oberhauser, Werner; Matt, Dominique; Toupet, Loic

    2014-04-01

    Two confining phosphane ligands derived from either ?- or ?-cyclodextrin produce singly P(III) -ligated metal complexes with unusual coordination spheres. High-pressure NMR studies have revealed that rhodium hydride complexes of the same type are also formed under hydroformylation conditions. This unique feature strongly favors the formation of the branched aldehyde at the expense of the linear one with high enantioselectivity in the rhodium-catalyzed hydroformylation of styrene. PMID:24590681

  16. Hydroformylation of allyl alcohol in the presence of modified rhodium catalysts

    SciTech Connect

    Korneyeva, G.A.; Chekhova, R.V.; Potarin, M.M.

    1993-12-31

    Reactions of hydroformylation of allyl alcohol and propene differ considerably. Thus certain peculiar features have been observed in the kinetic mechanisms of hydroformylation of propene and allyl alcohol in the presence of HRh(CO)(PPh){sub 3}; these include intense oxidation of the PPh{sub 3} contained in the rhodium catalyst under the action of the OH group of allyl alcohol, and also differences in regioselectivity when these substrates are used.

  17. Asymmetric hydroformylation of Z-enamides and enol esters with rhodium-bisdiazaphos catalysts.

    PubMed

    Abrams, M Leigh; Foarta, Floriana; Landis, Clark R

    2014-10-15

    Asymmetric hydroformylation (AHF) of Z-enamides and Z-enol esters provides chiral, alpha-functionalized aldehydes with high selectivity and atom economy. Rh-bisdiazaphospholane catalysts enable hydroformylation of these challenging disubstituted substrates under mild reaction conditions and low catalyst loadings. The synthesis of a protected analog of l-DOPA demonstrates the utility of AHF for enantioselective, atom-efficient synthesis of peptide precursors. PMID:25241657

  18. A novel triphosphoramidite ligand for highly regioselective linear hydroformylation of terminal and internal olefins.

    PubMed

    Chen, Caiyou; Qiao, Yu; Geng, Huiling; Zhang, Xumu

    2013-03-01

    The first triphosphorus ligand has been designed and synthesized for highly regioselective linear hydroformylations. A very high l/b ratio (up to 471, 99.8% linear selectivity) was obtained in the linear hydroformylation of representative terminal and internal olefins. For the range of substrates tested, the regioselectivities achieved utilizing the novel triphosphoramidite ligand were much better than those of the bisphosphoramidite ligand and close to those of the tetraphosphoramidite ligand. PMID:23405990

  19. Bis(phosphite) ligands with distal regulation: application in rhodium-mediated asymmetric hydroformylations.

    PubMed

    Mon, Ignasi; Jose, D Amilan; Vidal-Ferran, Anton

    2013-02-18

    Small amounts of achiral polyether binders are employed to enhance the enantioselectivity of the hydroformylation of an array of diversely substituted substrates (increase of up to 62% ee for vinyl acetate) mediated by chiral rhodium complexes derived from the ?,?-bis(phosphite)-polyether ligands 1. To the best of our knowledge, this study represents an unprecedented successful example of the positive regulation of enantioselectivity in hydroformylations. PMID:23307626

  20. The regioselective hydroformylation of vinylsilanes. A remarkable difference in the selectivity and reactivity of cobalt, rhodium, and iridium catalysts

    SciTech Connect

    Crudden, C.M.; Alper, H.

    1994-06-03

    Rhodium, iridium, and cobalt complexes were evaluated as catalysts for hydroformylation of vinylsilanes. Regioselectivities, product structures, and reaction yields were widely variable for these catalysts.

  1. Self-regulation effect in the hydroformylation reaction of olefins

    SciTech Connect

    Kagan, Yu.B.; Rozovskii, A.Ya.; Slivinskii, E.V.; Korneeva, G.A.; Kurkin, V.I.; Loktev, S.M.

    1988-06-01

    It has been demonstrated that under the conditions of vigorous olefin hydroformylation, stabilization and even partial regeneration of the activity of the rhodium carbonyl catalyst, deactivated by the formation of the polynuclear carbonyl clusters, are observed. The accumulation of a superequilibrium concentration of active rhodium carbonyl catalyst species, which are labile and thermodynamically unstable outside of the catalysis conditions, is achieved under the influence of the reaction conditions, in agreement with theoretical predictions. Based on IR spectroscopic studies, which were conducted in situ, the relay function of the catalytic reaction has been found to be due to the presence of a common hydrogenolysis step of rhodium acylcarbonyl derivatives during the catalytic reaction and during catalyst deactivation.

  2. Capsule-controlled selectivity of a rhodium hydroformylation catalyst.

    PubMed

    Bocoki?, Vladica; Kalkan, Ayfer; Lutz, Martin; Spek, Anthony L; Gryko, Daniel T; Reek, Joost N H

    2013-01-01

    Chemical processes proceed much faster and more selectively in the presence of appropriate catalysts, and as such the field of catalysis is of key importance for the chemical industry, especially in light of sustainable chemistry. Enzymes, the natural catalysts, are generally orders of magnitude more selective than synthetic catalysts and a major difference is that they take advantage of well-defined cavities around the active site to steer the selectivity of a reaction via the second coordination sphere. Here we demonstrate that such a strategy also applies for a rhodium catalyst; when used in the hydroformylation of internal alkenes, the selectivity of the product formed is steered solely by changing the cavity surrounding the metal complex. Detailed studies reveal that the origin of the capsule-controlled selectivity is the capsule reorganization energy, that is, the high energy required to accommodate the hydride migration transition state, which leads to the minor product. PMID:24150228

  3. Capsule-controlled selectivity of a rhodium hydroformylation catalyst

    NASA Astrophysics Data System (ADS)

    Bocoki?, Vladica; Kalkan, Ayfer; Lutz, Martin; Spek, Anthony L.; Gryko, Daniel T.; Reek, Joost N. H.

    2013-10-01

    Chemical processes proceed much faster and more selectively in the presence of appropriate catalysts, and as such the field of catalysis is of key importance for the chemical industry, especially in light of sustainable chemistry. Enzymes, the natural catalysts, are generally orders of magnitude more selective than synthetic catalysts and a major difference is that they take advantage of well-defined cavities around the active site to steer the selectivity of a reaction via the second coordination sphere. Here we demonstrate that such a strategy also applies for a rhodium catalyst; when used in the hydroformylation of internal alkenes, the selectivity of the product formed is steered solely by changing the cavity surrounding the metal complex. Detailed studies reveal that the origin of the capsule-controlled selectivity is the capsule reorganization energy, that is, the high energy required to accommodate the hydride migration transition state, which leads to the minor product.

  4. Rhodium catalysed hydroformylation of alkenes using highly fluorophilic phosphines.

    PubMed

    Adams, Dave J; Bennett, James A; Cole-Hamilton, David J; Hope, Eric G; Hopewell, Jonathan; Kight, Jo; Pogorzelec, Peter; Stuart, Alison M

    2005-12-21

    Highly fluorophilic phosphines incorporating at least one aromatic ring containing two directly attached perfluoroalkyl groups have been synthesised, their partition coefficients (organic phase : fluorous phase) measured and their electronic properties probed using (1)J(PtP) data for their trans-[PtCl(2)L(2)] complexes. These phosphines have been used as modifying ligands for the rhodium catalysed hydroformylation of 1-octene in perfluorocarbon solvents. Catalyst activity, regioselectivity and the levels of rhodium leaching to the product phase vary with the substitution patterns of the modifying ligands that do not correlate with the electronic properties or partition coefficients of these ligands, but can be interpreted in terms of differences in the resting states of the catalysts. PMID:16311639

  5. Dynamic and LHHW kinetic analysis of heterogeneous catalytic hydroformylation

    SciTech Connect

    Balakos, M.W.; Chuang, S.S.C.

    1995-02-01

    Heterogeneous ethylene hydroformylation on a 4 wt% Rh/SiO{sub 2} catalyst was studied using a steady-state pulse transient method coupled with in situ infrared spectroscopy. Four independent quantities, including the rates of propionaldehyde and ethane formation and the surface coverages of adsorbed CO and adsorbed acyl species, were measured at steady state as a function of the partial pressures of the reactants. The coverage of intermediates during ethylene hydroformylation was determined from the dynamic response of C{sub 2}H{sub 5}{sup 13}CHO to a {sup 13}CO pulse input. The coverage of adsorbed CO was measured by in situ IR spectroscopy. The rate laws for C{sub 2}H{sub 5}CHO and C{sub 2}H{sub 6} formation and the isotherm equations for adsorbed C{sub 2}H{sub 5}CO and adsorbed CO were derived using the Langmuir-Hinshelwood-Hougen-Watson (LHHW) approach from a proposed mechanism with the hydrogenation of adsorbed C{sub 2}H{sub 5}CO as the rate-determining step for propionaldehyde formation and the hydrogenation of adsorbed C{sub 2}H{sub 5} as the rate-determining step for ethane formation. The high degree of fitting of rate and coverage data to the derived rate law and isotherm equations suggests that the LHHW model describes the surface reaction with high accuracy. Although the assumptions for the Langmuir isotherm do not account for the interactions between adsorbates, the LHHW equations and the proposed mechanism satisfactorily describe the kinetics, reaction pathways, and rate-limiting steps for the formation of ethane and propionaldehyde. This study demonstrates that the measurement of coverage of adsorbates by isotopic tracer pulsing and in situ infrared spectroscopy provides direct experimental evidence to confirm a postulated mechanism and rate law. 46 refs., 10 figs., 3 tabs.

  6. Cluster formation as the cause of deactivation of carbonyl-rhodium catalysts in hydroformylation of olefins

    SciTech Connect

    Kagan, Yu.B.; Slivinskii, Ye.V.; Kurkin, V.I.; Korneyeva, G.A.; Aranovich, R.A.; Fal'kov, I.G.; Rzhevskaya, N.N.; Loktev, S.M.

    1985-01-01

    Carbonyl-rhodium catalysts - under conditions of hydroformylation of olefins without one or several reagents, are deactivated as a result of irreversible formation of polynuclear clusters. The composition and properties of clusters formed during deactivation are determined. The rate mechanism of cluster-formation are found to depend on the medium, in which the process takes place. Hydrogen has the most marked effect. Cluster formation takes place in stages. The first stages of this process yields clusters with relatively low MW, which during hydroformylation take part in the removal of clusters, resulting in partial reactivation of the catalyst.

  7. Hydroformylation in the presence of a rhodium catalyst promoted by sodium alcoholate

    SciTech Connect

    Korneyeva, G.A.; Chekhova, R.V.; Loktev, S.M.

    1993-12-31

    The effect of additive NaOR (R = CH{sub 3}, C{sub 2}H{sub 5}, C{sub 4}H{sub 9}) on the rate and selectivity of hydroformylation of allyl alcohol and propene in the presence of unmodified and modified triphenylphosphine rhodium catalysts has been shown. The dependence of the indices of hydroformylation on the ratios Na/Rh and PPh{sub 3}/Rh and the nature of R and also the results of an IR spectral study of the catalytic complex indicate that the active Rh catalyst contains an OR group. 14 refs., 5 figs.

  8. Hydroformylation of 1-heptene catalyzed by ruthenium cluster

    SciTech Connect

    Li, Z.; Zhang, J.; Wang, C.

    1994-12-31

    Hydroformylation of 1-heptane catalyzed by homogeneous and heterogeneous Ru{sub 3}(CO){sub 12} catalyst has been investigated. Ru{sub 3}(CO){sub 12} has almost no activity when reaction temperature is below 60 C, and nearly stable activity when over 100 C. The maximum selectivity to aldehyde is obtained at 120 C and N/I values of aldehyde and alcohol decrease rapidly with temperature increase. Supported Ru{sub 3}(CO){sub 12} catalyst modified with NaBH{sub 4} or KOH has higher catalytic activity and selectivity to aldehyde in heterogeneous catalysis. Compared with supported Ru{sub 3}(CO){sub 12} catalyst modified with NaBH{sub 4} or KOH has higher catalytic activity and selectivity to aldehyde in heterogeneous catalysis. Compared with supported Ru{sub 3}(CO){sub 12} catalysts, Ru{sub 3}(CO){sub 12}/Co{sub 2}(CO){sub 8}/{gamma}-Al{sub 2}O{sub 3} has high activity and selectivity. When PPh{sub 3} or (NEt{sub 4}) Cl is added to the reaction system, the selectivity to aldehyde and N/I increase. The FTIR spectra of catalysts after reaction show that Ru{sub 3}(CO){sub 12} and Co{sub 2}(CO){sub 8} are changed to new carbonyl complexes which may have catalytic activity.

  9. Onium chains-silica as catalytic support: Application to hydroformylation

    SciTech Connect

    Hong, L.; Ruckenstein, E. )

    1993-09-01

    Polymer chains of quaternary oniums are deposited on the surface of hydrophilic silica by the radical polymerization of water-soluble quaternary onium monomers present in a water medium which imbibes the porous silica. The modified (quaternized) silica surface which contains a small amount of water is a more suitable support than silica, since it provides anchors for the catalytic species and sites for the adsorption of reactant molecules. It is used as substrate for the immobilization of monosulfonated triphenylphosphine (DPM) and of its rhodium carbonyl complex Cl(CO)Rh(DPM)[sub 2], through an ion-exchange process. The immobilized catalytic system containing a small amount of water was employed in the hydroformylation of styrene and ethyl 10-undecenoate. The presence of ethanol in the reaction medium is necessary to achieve a high yield of aldehydes. For styrene, the ratio of the isomer to the normal aldehyde is greater than 6, while for ethyl 10-undecenoate, it is 1/8. Structural factors that affect the regioselectivities of the aldehydes are suggested as possible explanations for the above ratios. The performance of the catalyst has remained almost unchanged during several reuses. 23 refs., 6 figs., 4 tabs.

  10. Facile catalyst separation without water: Fluorous biphase hydroformylation of olefins

    SciTech Connect

    Horvath, I.T.; Rabai, J.

    1994-10-07

    A novel concept for performing stoichiometric and catalytic chemical transformations has been developed that is based on the limited miscibility of partially or fully fluorinated compounds with nonfluorinated compounds. A fluorous biphase system (FBS) consists of a fluorous phase containing a dissolved reagent or catalyst and another phase, which could be any common organic or nonorganic solvent with limited or no solubility in the fluorous phase. The fluorous phase is defined as the fluorocarbon (mostly perfluorinated alkanes, ethers, and tertiary amines)-rich phase of a biphase system. An FBS compatible reagent or catalyst contains enough fluorous moieties that it will be soluble only or preferentially in the fluorous phase. The most effective fluorous moieties are linear or branched perfuoralkyl chains with high carbon number; they may also contain heteroatoms. The chemical transformation may occur either in the fluorous phase or at the interface of the two phases. The application of FBS has been demonstrated for the extraction of rhodium from toluene and for the hydroformylation of olefins. The ability to separate a catalyst or a reagent from the products completely at mild conditions could lead to industrial application of homogeneous catalysts or reagents and to the development of more environmentally benign processes.

  11. Greener Hydroformylation with Nanofilterable Rhodium Catalysts in A Stirred Membrane Reactor

    E-print Network

    Xie, Zhuanzhuan

    2013-05-31

    concept for continuous hydroformylation in CXLs was demonstrated using bulky phosphite ligands that are effectively retained in the stirred reactor by a nanofiltration membrane. The reactor was operated at 50 °C with a syngas pressure of 6 bar to avoid CO...

  12. Total Synthesis of Sedum Alkaloids via Catalyst Controlled aza-Cope Rearrangement and Hydroformylation with Formaldehyde

    PubMed Central

    Ren, Hong; Wulff, William D.

    2013-01-01

    The catalytic asymmetric aminoallylation of chiral aldehydes is developed as a new method for the catalyst controlled synthesis of syn- and anti-1,3-aminoalcohols. This methodology is highlighted in the synthesis of the sedum alkaloids (+)-sedridine and (+)-allosedridine both of which have their final carbon incorporated during closure of the piperidine ring via a hydroformylation with formaldehyde. PMID:23259754

  13. Synthesis of optically pure 2-trifluoromethyl lactic acid by asymmetric hydroformylation.

    PubMed

    Wang, Xiao; Buchwald, Stephen L

    2013-04-01

    By utilizing Rh catalysts ligated by the P-chirogenic ligands QuinoxP* and DuanPhos, 3,3,3-trifluoroprop-1-en-2-yl acetate could be hydroformylated and subsequently oxidized to yield enantiomerically pure 2-trifluoromethyllactic acid. PMID:23394066

  14. Enantioselective Hydroformylation of 1-Alkenes with Commercial Ph-BPE Ligand.

    PubMed

    Yu, Zhiyong; Eno, Meredith S; Annis, Alexandra H; Morken, James P

    2015-07-01

    A rhodium complex, in conjunction with commercially available Ph-BPE ligand, catalyzes the branch-selective asymmetric hydroformylation of 1-alkenes and rapidly generates ?-chiral aldehydes. A wide range of terminal olefins including 1-dodecene were examined, and all delivered high enantioselectivity (up to 98:2 er) as well as good branch:linear ratios (up to 15:1). PMID:26091063

  15. A novel rhodium-catalyzed domino-hydroformylation-reaction for the synthesis of sulphonamides.

    PubMed

    Dong, Kaiwu; Fang, Xianjie; Jackstell, Ralf; Beller, Matthias

    2015-03-25

    An efficient and highly selective method for the synthesis of sulphonamides by a domino hydroformylation-reductive sulphonamidation reaction has been developed. Various olefins and sulphonamides are converted into the desired products in good yields and with excellent selectivities in the presence of a rhodium/Naphos catalyst. PMID:25712242

  16. Domino hydroformylation/aldol condensation/hydrogenation catalysis: highly selective synthesis of ketones from olefins.

    PubMed

    Fang, Xianjie; Jackstell, Ralf; Börner, Armin; Beller, Matthias

    2014-11-24

    A general and highly chemo- and regioselective synthesis of ketones from olefins by domino hydroformylation/aldol condensation/hydrogenation reaction has been developed. A variety of olefins are efficiently converted into various ketones in good to excellent yields and regioselectivities in the presence of a specific rhodium phosphine/base-acid catalyst system. PMID:25331557

  17. Total synthesis of sedum alkaloids via catalyst controlled aza-Cope rearrangement and hydroformylation with formaldehyde.

    PubMed

    Ren, Hong; Wulff, William D

    2013-01-18

    The catalytic asymmetric aminoallylation of chiral aldehydes is developed as a new method for the catalyst controlled synthesis of syn- and anti-1,3-aminoalcohols. This methodology is highlighted in the synthesis of the sedum alkaloids (+)-sedridine and (+)-allosedridine both of which have their final carbon incorporated during closure of the piperidine ring via a hydroformylation with formaldehyde. PMID:23259754

  18. Water gas shift reaction and in the hydroformylation and hydrohydroxyformylation reactions

    SciTech Connect

    Laine, R.M.

    1980-10-07

    In the water gas shift reaction, H2O+CO -> H2+CO2 and more particularly in hydroformylation of olefins, e.g. ethylene, a homogeneous catalysts is used. A mixed ruthenium carbonyl/iron carbonyl catalyst in solution is the improvement.

  19. Ordered mesoporous materials as solid supports for rhodium-diphosphine catalysts with remarkable hydroformylation activity.

    PubMed

    Marras, Fabrizio; Wang, Jia; Coppens, Marc-Olivier; Reek, Joost N H

    2010-09-21

    A rhodium-diphosphine complex based on Xantphos-type ligands was anchored on mesoporous silica SBA-15, and the material showed remarkably high catalytic activity in the hydroformylation of 1-octene, even exceeding its homogeneous analogue under certain conditions. PMID:20697633

  20. Efficient Domino Hydroformylation/Benzoin Condensation: Highly Selective Synthesis of ?-Hydroxy Ketones.

    PubMed

    Dong, Kaiwu; Sang, Rui; Soule, Jean-Francois; Bruneau, Christian; Franke, Robert; Jackstell, Ralf; Beller, Matthias

    2015-12-01

    An improved domino hydroformylation/benzoin condensation to give ?-hydroxy ketones has been developed. Easily available olefins are smoothly converted into the corresponding ?-hydroxy ketones in high yields with excellent regioselectivities. Key to success is the use of a specific catalytic system consisting of a rhodium/phosphine complex and the CO2 adduct of an N-heterocyclic carbene. PMID:26503672

  1. Highly dispersed metal atoms in zeolites. Progress report. [Hydroformylation

    SciTech Connect

    Suib, S.L.

    1985-04-15

    Our studies this past year have involved work in the following areas: preparation of highly dispersed metal atoms in molecular sieves via microwave discharge methods, hydroformylation of l-pentene with rhodium zeolites and Rutherford backscattering studies of zeolites. The microwave discharge method has been developed by us to provide a synthetic route to produce highly dispersed iron and cobalt atom clusters in several molecular sieves such as zeolites, aluminophosphates, pillared clays and clays. We have done ferromagnetic resonance, infrared, Mossbauer and scanning electron microscopy experiments on these materials. Generalizations that can be made so far are that these particles are extremely small, reactive and their formation is governed by the type of support. They are all active in Fischer-Tropsch reactions although cobalt materials are more selective and stable than iron materials. Superparamagnetic iron clusters have been observed for the incorporation of iron into zeolites, ALPO's and pillared clays. These results are unique in that iron (0) is usually oxidized in a zeolite environment. The second project deals with Wilkinson's catalyst and the preparation of phosphine rhodium zeolite catalysts. These catalysts are selective towards aldehyde formation and the normal to branched aldehyde ratio can be controlled. EXAFS, Fourier transform infrared and x-ray powder diffraction experiments have been carried out on these catalysts. The third project deals with Rutherford backscattering studies of zeolites. We have shown that Rutherford backscattering methods can be used to distinguish metal ions on the surface of a porous support from internal metal ions exchanged into the pores of the support.

  2. A silica-supported, switchable, and recyclable hydroformylation-hydrogenation catalyst.

    PubMed

    Sandee, A J; Reek, J N; Kamer, P C; van Leeuwen, P W

    2001-09-01

    A homogeneous hydroformylation catalyst, designed to produce selectively linear aldehydes, was covalently tethered to a polysilicate support. The immobilized transition-metal complex [Rh(A)CO]+(1+)), in which A is N-(3-trimethoxysilane-n-propyl)-4,5-bis(diphenylphosphino)phenoxazine, was prepared both via the sol-gel process and by covalent anchoring to silica. 1+ was characterized by means of (31)P and (29)Si MAS NMR, FT-IR, and X-ray photoelectron spectroscopy. Polysilicate immobilized Rh(A) performed as a selective hydroformylation catalyst showing an overall selectivity for the linear aldehyde of 94.6% (linear to branched aldehyde ratio of 65). In addition 1-nonanol, obtained via the hydrogenation of the corresponding aldehyde, was formed as an unexpected secondary product (3.6% at 20% conversion). Under standard hydroformylation conditions, 1+ and HRh(A)(CO)(2)(1) coexist on the support. This dual catalyst system performed as a hydroformylation/hydrogenation sequence catalyst (Z), giving selectively 1-nonanol from 1-octene; ultimately, 98% of 1-octene was converted to mainly 1-nonanal and 97% of the nonanal was hydrogenated to 1-nonanol. The addition of 1-propanol completely changes Z in a hydroformylation catalyst (X), which produces 1-nonanal with an overall selectivity of 93%, and completely suppresses the reduction reaction. If the atmosphere is changed from CO/H(2) to H(2) the catalyst system is switched to the hydrogenation mode (Y), which shows a clean and complete hydrogenation of 1-octene and 1-nonanal within 24 h. The immobilized catalyst can be recycled and the system can be switched reversibly between the three "catalyst modes" X, Y, and Z, completely retaining the catalyst performance in each mode. PMID:11525653

  3. Development of heterogeneous catalysts for hydroformylation of 1-hexene in supercritical carbon dioxide

    NASA Astrophysics Data System (ADS)

    Marteel, Anne Eugenie

    The hydroformylation of alkenes is a major commercial process used for the production of oxygenated organic compounds. When the hydroformylation reaction is performed using a homogeneous catalyst, an organic or aqueous solvent is employed and a significant effort must be expended to recover the catalyst so it can be recycled. The hydroformylation of long-chain alkenes using homogeneous catalysts in aqueous solution is compromised because of the low-solubility of C5 alkenes and above. Development of a selective heterogeneous catalyst would allow simplification of the process design in an integrated system that minimizes waste generation. Recent studies have shown that a supercritical fluid may be used as a solvent for hydroformylation reactions. The use of carbon dioxide as a reaction solvent offers optimal environmental performance because it is non-toxic, non-flammable and plentiful, and presents advantages for ease of product separation. In particular, we have considered the conversion of 1-hexene to heptanal using rhodium-phosphine catalysts tethered to supports insoluble in supercritical carbon dioxide to demonstrate the advantages and understand the limitations of a solid-catalyzed process. One of the limitations of supported catalysts is the inability to control product selectivity. To remedy this problem, we have developed tethered rhodium-phosphine catalysts with modified silica and controlled-pore size MCM-41 and MCM-20 supports that provide improved selectivity and conversion relative to their nonporous equivalents. Platinum and palladium catalysts analogous to those of rhodium were also investigated. The synthesis and characterization of the rhodium, platinum and palladium complexes and evaluation of their catalytic activity and selectivity for hydroformylation in supercritical carbon dioxide is described in this dissertation.

  4. "Solventless" continuous flow homogeneous hydroformylation of 1-octene.

    PubMed

    Frisch, Anja C; Webb, Paul B; Zhao, Guoying; Muldoon, Mark J; Pogorzelec, Peter J; Cole-Hamilton, David J

    2007-12-21

    The hydroformylation of 1-octene under continuous flow conditions is described. The system involves dissolving the catalyst, made in situ from [Rh(acac)(CO)(2)] (acacH=2,4-pentanedione) and [RMIM][TPPMS] (RMIM=1-propyl (Pr), 1-pentyl (Pn) or 1-octyl (O) -3-methyl imidazolium, TPPMS=Ph(2)P(3-C(6)H(4)SO(3))), in a mixture of nonanal and 1-octene and passing the substrate, 1-octene, together with CO and H(2) through the system dissolved in supercritical CO(2) (scCO(2)). [PrMIM][TPPMS] is poorly soluble in the medium so heavy rhodium leaching (as complexes not containing phosphine) occurs in the early part of the reaction. [PnMIM][TPPMS] affords good rates at relatively low catalyst loadings and relatively low overall pressure (125 bar) with rhodium losses <1 ppm, but the catalyst precipitates at higher catalyst loadings, leading to lower reaction rates. [OMIM][TPPMS] is the most soluble ligand and promotes high reaction rates, although preliminary experiments suggested that rhodium leaching was high at 5-10 ppm. Optimisation aimed at balancing flows so that the level within the reactor remained constant involved a reactor set up based around a reactor fitted with a sight glass and sparging stirrer with the CO(2) being fed by a cooled head HPLC pump, 1-octene by a standard HPLC pump and CO/H(2) through a mass flow controller. The pressure was controlled by a back pressure regulator. Using this set up, [OMIM][TPPMS] as the ligand and a total pressure of 140 bar, it was possible to control the level within the reactor and obtain a turnover frequency of ca. 180 h(-1). Rhodium losses in the optimised system were 100 ppb. Transport studies showed that 1-octene is preferentially transported over the aldehydes at all pressures, although the difference in mol fraction in the mobile phase was less at lower pressures. Nonanal in the mobile phase suppresses the extraction of 1-octene to some extent, so it is better to operate at high conversion and low pressure to optimise the extraction of the products relative to the substrate. CO and H(2) in the mobile phase also suppress the extraction efficiency by as much as 80%. PMID:18043813

  5. Rapid Asymmetric Transfer Hydroformylation (ATHF) of Disubstituted Alkenes Using Paraformaldehyde as a Syngas Surrogate

    PubMed Central

    Fuentes, José A; Pittaway, Rachael; Clarke, Matthew L

    2015-01-01

    As an alternative to conventional asymmetric hydroformylation (AHF), asymmetric transfer hydroformylation (ATHF) by using formaldehyde as a surrogate for syngas is reported. A catalyst derived from commercially available [Rh(acac)(CO)2] (acac=acetylacetonate) and 1,2-bis[(2S,5S)-2,5-diphenylphospholano]ethane(1,5-cyclooctadiene) (Ph-BPE) stands out in terms of both activity and enantioselectivity. Remarkably, not only are high selectivities achievable, the reactions are very simple to perform, and higher enantioselectivity (up to 96 % ee) and/or turnover frequencies than those achievable by using the same catalyst (or other leading catalysts) can be obtained by using typical conditions for AHF. PMID:26114239

  6. Hydroformylation of 1-octene in the presence of cobalt alkylidynecarbonyl clusters

    SciTech Connect

    Tsoy, A.A.; Kayumov, F.F.; Grudtsyn, Yu.D.

    1994-02-01

    The hydroformylation of 1-octene in the presence of Co{sub 3}(CO){sub 9}({mu}-CR) (R = H, Me, Ph, CO{sub 2}Me, CO{sub 2}Et, CO{sub 2}Pr{sup i}, CO{sub 2}Bu{sup t}, Cl, Br, OMe) alkylidynecarbonyl clusters, as well as triphenylphosphine derivatives of these complexes and heteronuclear Co{sub 2}Ni compounds have been studied. The nature of the catalytically active species in hydroformylation, as well as the processes of their formation and transformation during the reaction, have been established by means of IR spectroscopy, The effects of the reaction conditions, the nature of the substituent at the apical carbon atom, the electron donating phosphine substituent, and the substituent in the metal cluster framework have been discussed.

  7. Rapid Asymmetric Transfer Hydroformylation (ATHF) of Disubstituted Alkenes Using Paraformaldehyde as a Syngas Surrogate.

    PubMed

    Fuentes, José A; Pittaway, Rachael; Clarke, Matthew L

    2015-07-20

    As an alternative to conventional asymmetric hydroformylation (AHF), asymmetric transfer hydroformylation (ATHF) by using formaldehyde as a surrogate for syngas is reported. A catalyst derived from commercially available [Rh(acac)(CO)2 ] (acac=acetylacetonate) and 1,2-bis[(2S,5S)-2,5-diphenylphospholano]ethane(1,5-cyclooctadiene) (Ph-BPE) stands out in terms of both activity and enantioselectivity. Remarkably, not only are high selectivities achievable, the reactions are very simple to perform, and higher enantioselectivity (up to 96?% ee) and/or turnover frequencies than those achievable by using the same catalyst (or other leading catalysts) can be obtained by using typical conditions for AHF. PMID:26114239

  8. Ruthenium-catalyzed hydroformylation/reduction of olefins to alcohols: extending the scope to internal alkenes.

    PubMed

    Wu, Lipeng; Fleischer, Ivana; Jackstell, Ralf; Profir, Irina; Franke, Robert; Beller, Matthias

    2013-09-25

    In the presence of 2-phosphino-substituted imidazole ligands and Ru3(CO)12 or Ru(methylallyl)2(COD) direct hydroformylation and hydrogenation of alkenes to alcohols takes place. In addition to terminal alkenes, also more challenging internal olefins are converted preferentially to industrially important linear alcohols in high yield (up to 88%) and regioselectivity (n:iso up to 99:1). PMID:23987582

  9. Comparison of ethylene with propylene hydroformylation over a Rh-Y zeolite catalyst under atmospheric pressure

    SciTech Connect

    Takahashi, N.; Kobayashi, M.

    1984-01-01

    Hydroformylation of ethylene and propylene over the Rh-Y zeolite was carried out in a continuous-flow system under atmospheric pressure. The activity of the catalyst used for the formation of propionaldehyde and butyraldehyde was observed to be constant for a period of over 1 month. Pretreatment of the catalyst with He-H/sub 2/ (10%) at 127/sup 0/C considerably affected the steady-state rate (r/sub PA/) and the apparent activation energy (E/sub PA/) for the propionaldehyde formation. On the Rh-Y zeolite with a rhodium content of less than 110 x 10/sup -6/ mol/g cat (1.13 wt%), the enhancement in r/sub PA/ was observed with no appreciable change in E/sub PA/. On the other hand, on the Rh-Y zeolite (No. 6) with a rhodium content of 280 x 10/sup -6/ mol/g cat (2.88 wt%), r/sub PA/ was somewhat reduced by the pretreatment while E/sub PA/ was considerably enhanced, i.e., 40 kJ/mol on the untreated catalyst and 56 kJ/mol on the pretreated one. In the propylene hydroformylation, the pretreatment of the Rh-Y (No.6) remarkably reduced r/sub BA/ compared with r/sub PA/, but it enhanced the n-isomer selectivity (S/sub n-BA/). The enhancement in S/sub n-BA/ is closely related to the enhancement in E/sub PA/. On the basis of the results obtained, it is concluded that 1) the active sites formed either at the entrance of the pore or the external surface can effectively catalyze both the hydroformylation of ethylene and propylene and 2) the active sites formed in the pore at a very short distance from the entrance can catalyze the hydroformylation of ethylene but not propylene. 7 figures, 2 tables.

  10. Asymmetric Hydroformylation of Heterocyclic Olefins Mediated by Supramolecularly Regulated Rhodium-Bisphosphite Complexes.

    PubMed

    Rovira, Laura; Vaquero, Mónica; Vidal-Ferran, Anton

    2015-10-16

    Rhodium complexes derived from conformationally transformable ?,?-bisphosphite ligands combined with a suitable alkali metal BArF salt as a regulation agent (RA) provide high regio- and enantioselectivities in the asymmetric hydroformylation (AHF) of three heterocyclic olefins. The outcome of the AHF could be exquisitely regulated by choosing the appropriate RA with an increase in the ee, the reversal of the regioselectivity, or the complete suppression of one byproduct. PMID:26355601

  11. High-precision catalysts: regioselective hydroformylation of internal alkenes by encapsulated rhodium complexes.

    PubMed

    Kuil, Mark; Soltner, Theresa; van Leeuwen, Piet W N M; Reek, Joost N H

    2006-09-01

    We report the formation of high-precision catalysts using encapsulated rhodium complexes. In the current example, the encapsulated rhodium catalyst shows unprecedented high selectivity in the rhodium-catalyzed hydroformylation of internal alkenes, forming predominantly one of the branched aldehydes. This catalyst system is the first example that is able to discriminate between carbon atoms C3 and C4 in trans-3-octene. PMID:16939244

  12. Libraries of bisdiazaphospholanes and optimization of rhodium-catalyzed enantioselective hydroformylation.

    PubMed

    Adint, Tyler T; Wong, Gene W; Landis, Clark R

    2013-05-01

    Twelve chiral bis-3,4-diazaphospholane ligands and six alkene substrates (styrene, vinyl acetate, allyloxy-tert-butyldimethylsilane, (E)-1-phenyl-1,3-butadiene, 2,3-dihydrofuran, and 2,5-dihydrofuran) probe the influence of steric bulk on the activity and selectivity of asymmetric hydroformylation (AHF) catalysts. Reaction of an enantiopure bisdiazaphospholane tetraacyl fluoride with primary or secondary amines yields a small library of tetracarboxamides. For all six substrates, manipulation of reaction conditions and bisdiazaphospholane ligands enables state-of-the-art performance (90% or higher ee, good regioselectivity, and high turnover rates). For the nondihydrofuran substrates, the previously reported ligand, (S,S)-2, is generally most effective. However, optimal regio- and enantioselective hydroformylation of 2,3-dihydrofuran (up to 3.8:1 ?-isomer/?-isomer ratio and 90% ee for the ?-isomer) and 2,5-dihydrofuran (up to <1:30 ?-isomer/?-isomer ratio and 95% ee for the ?-isomer) arises from bisdiazaphospholanes containing tertiary carboxamides. Hydroformylation of either 2,3- or 2,5-dihydrofuran yields some of the ?-formyl product. However, the absolute sense of stereochemistry is inverted. A stereoelectronic map rationalizes the opposing enantiopreferences. PMID:23581247

  13. Aqueous-phase hydroformylation of 1-octene using hydrophilic sulfonate salicylaldimine dendrimers.

    PubMed

    Hager, Emma B; Makhubela, Banothile C E; Smith, Gregory S

    2012-12-01

    Water-soluble dendritic ligands based on tris-2-(5-sulfonato salicylaldimine ethyl)amine (5) and DAB-(5-sulfonato salicylaldimine) (6) (DAB = diaminobutane) were synthesized by means of Schiff base condensation and sulfonation reactions. These dendritic ligands were fully characterized by (1)H NMR, (13)C NMR and FT-IR spectroscopy, elemental analysis and mass spectrometry. Dendritic ligands (5 and 6) in combination with [RhCl(COD)](2) (COD = 1,5-cyclooctadiene) were evaluated in aqueous biphasic hydroformylation of 1-octene. New water-soluble mononuclear 5-sulfonato propylsalicylaldimine Rh(i) complexes (7 and 8) were synthesized and characterized using (1)H NMR, (13)C NMR and FT-IR spectroscopy, elemental analysis as well as mass spectrometry. These complexes were applied as catalyst precursors in aqueous biphasic hydroformylation reactions. All the catalyst precursors were active in the hydroformylation of 1-octene under the investigated conditions. Optimal conditions were realized at 75 °C (40 bars), where the best selectivity for aldehydes was noticed. Catalyst recycling was achieved up to 5 times with minimal loss in conversion and consistent chemoselectivities and regioselectivities. Less Rh leaching was observed in the dendritic systems (5 and 6)/[RhCl(COD)](2) as compared to mononuclear catalyst precursors (7 and 8) as determined by inductively coupled plasma-mass spectrometry (ICP-MS). PMID:23023586

  14. Synthese de nanoparticules plasmoniques par laser femtoseconde en milieu liquide pour des applications biomedicales

    NASA Astrophysics Data System (ADS)

    Besner, Sebastien

    The femtosecond laser synthesis of plasmonic nanoparticles (Au, Ag, Cu, AuAg, AuCu) is described. The approach relies on the fs laser ablation of a target immersed in a liquid, followed by the laser-induced fragmentation and growth of nanoparticles in solution. This two-step methodology significantly enhances the production rate, the reproducibility and the size control of nanoparticles in comparison to the direct laser ablation based technique. For gold, the laser-induced growth of nanometric seeds initially formed by laser ablation in the presence of a stabilizing agent allows the synthesis of functionalized nanoparticles with sizes ranging from 3-76 nm and coefficients of variation (COV) varying between 15-30%. In comparison to the direct laser ablation, the size control is much simpler, as it uniquely depends on the gold to stabilizing agent molecular concentration ratio. The approach has been described for dextran and polyethylene glycol (PEG), but can be extended to all stabilizing agents and open new avenues in the formation of various novel bioconjugates. The fs laser ablation and fragmentation also allow the synthesis of stable and low dispersed Au nanoparticles in pure water. These nanoparticles are unique for sensing applications with high sensitivity based on surface enhanced Raman scattering (SERS), since they greatly reduce the noise associated with surface contaminants and byproducts found in solution. The formation of various nanospheres with predetermined size, shape and composition (AuxAg(1-x), AuxCu(1-x) ) is also reported by the use of a fs irradiation of a mixture of two pure metallic ix colloidal solutions in a very simple chemical environment, e.g. water and a stabilizing agent. From a chemical point of view, oxidation of silver nanoparticles is significantly reduced by the incorporation of a small amount of gold and is completely inhibited for a gold atomic fraction larger than 0.4-0.5. The bifunctional nature related to the partial oxidation of the gold nanoparticle surface allows a wide range of stabilization mechanisms. The stabilization by hydrophobic-hydrophobic interaction, by hydrogen bonds formation, by chemisorptions of thiols and by electrostatic interactions is evaluated. A new class of stabilizing agents, biopolymers, is also introduced. The addition of these polymers during the laser ablation, fragmentation or growth process enables in situ surface functionalization and efficient size control. The biocompatibility of these stabilizers also allows the direct introduction of nanoparticles in in vitro or in vivo applications without further purification. Significant efforts have also been undertaken to check the possible degradation of the polymers used during the laser process. These studies demonstrate a low degradation via an oxidation mechanism, involving the production of free radicals and oxidizing species by dissociation of water molecules during the laser process. Finally, the mechanisms of laser ablation in liquids and a growth model for the nanoparticles are proposed based on experimental results from literature and this thesis. The formation of nanoparticles is described by three distinct phases. First, a fast nucleation and condensation of the ejected species occur in the plasma and are caused by extremely high cooling rates, which lead to a strong supersaturation. This short nucleation and condensation phase is followed by a marked growth of the liquid (and still hot) nuclei by coalescence. After solidification, these nuclei should have sizes below 2 nm and be mostly condensed at the liquid-vapor interface of the growing cavitation bubble. Without the presence of stabilizing agent, growth by atomic diffusion and coalescence continue inside the cavitation bubble and should be accelerated following its collapse. Nanoparticles and unreacted monomers are then propelled out of the ablation zone by the secondary shock wave associated with the collapse of the cavitation bubble and further grow in solution. This cycle is repeated for each laser pulse and interaction between species

  15. Arylolefin hydroformylation catalyses by Rh(AcAc)(CO){sub 2} modified with phosphorus-containing ligands

    SciTech Connect

    Korneyeva, G.A.; Vladimirova, T.V.; Potarin, M.M.

    1993-12-31

    An investigation has been made of the hydroformylation of styrene, {alpha}-methylstyrene, p-methylstyrene and p-acetoxy-{alpha}-methylstyrene in the presence of a catalytic system containing Rh(AcAc)(CO){sub 2} modified with triphenylphosphine and phosphite ligands of different structure at t = 80{degrees}C and P = 6 MPa (CO)/H{sub 2} = 1. The formation of catalytic forms of rhodium complexes has been studied by means of in situ IR spectral measurements. If Rh(AcAc)(CO){sub 2}, modified with triphenylphosphine is used as the catalyst, oxygen-containing substrates are inactive in hydroformylation on account of the coordination of the substrate with the rhodium atom by the oxygen atom. The use of phosphate ligands made it possible to produce active catalysts for the hydroformylation of oxygen-containing substrates. 19 refs., 3 tabs.

  16. Mechanistic study of the hydroformylation of propene over silica-supported Rh and Pd catalysts: Effect of added sodium cation

    SciTech Connect

    Natio, Shuichi ); Tanimoto, Mitsutoshi )

    1991-07-01

    The mechanism of the hydroformylation of propene over silica-supported Rh and Pd catalysts was studied by isotope tracer technique with microwave spectroscopy and infrared spectroscopic technique as well as kinetic investigation. The rate-determining steps in the hydroformylation process were different over the two metals: hydrogenation of surface acyl species on Rh catalysts and CO insertion into surface propyl species on Pd catalysts. The structure and the reactivity of the surface propyl intermediates were determined by analyzing the isotope distribution of monodeuteropropene formed during C{sub 3}H{sub 6}-D{sub 2}-CO reaction with microwave spectroscopy. It was revealed that n-propyl species is more reactive for CO insertion than s-propyl species. Promotion effect of sodium cations on hydroformylation was also investigated in detail and different roles of sodium cations were demonstrated for Rh and Pd catalysts.

  17. Alkene hydrogenation and hydroformylation with CO and H{sub 2}O catalyzed by polymer-anchored rhodium complexes

    SciTech Connect

    Mdleleni, M.M.; Rinkre, R.G.; Ford, P.C.

    1995-12-01

    We have shown that catalysts derived from supporting RhCl{sub 3}-3H{sub 2}O on porous aminated polymers are active in the water gas shift reaction (WGSR). Those immobilized on poly (4-vinylpyridine) [P4VP] show long term activity in neutral aqueous and aqueous organic solvent media. The Rh/P4VP system is also active toward Reppe-type transformations (hydrogenation and hydroformylation) of alkenes. We have investigated the kinetics of alkene hydrogenation/hydroformylation catalyzed by the P4VP-bound rhodium system under WGSR conditions. Results of these investigations will be discussed.

  18. Rhodium-Catalyzed Hydroformylation of 1,1-Disubstituted Allenes Employing the Self-Assembling 6-DPPon System.

    PubMed

    Köpfer, Alexander; Breit, Bernhard

    2015-06-01

    A rhodium-catalyzed hydroformylation of 1,1-disubstituted allenes is reported. Using a Rh(I)/6-DPPon catalyst system, one can obtain ?,?-unsaturated aldehydes in high regio- and chemoselectivity. The Z-configured product is formed with up to >95% selectivity when unsymmetrically 1,1-disubstituted allenes are submitted to the reaction conditions. This is the first time that these interesting building blocks are accessible by hydroformylation of allenes. The utility of this methodology is demonstrated by further transformations of one of the obtained products. PMID:25917327

  19. Sequential hydroformylation/diels-alder processes: one-pot synthesis of polysubstituted cyclohexenes, cyclohexadienes, and phthalates from alkynes.

    PubMed

    Fang, Xianjie; Jackstell, Ralf; Beller, Matthias

    2014-06-23

    A novel, one-pot hydroformylation/Diels-Alder sequence for the synthesis of multisubstituted cyclohexenes, cyclohexadienes, and phthalates has been developed. Various alkynes were efficiently converted into the corresponding products in good yields and with excellent diastereoselectivity through palladium-catalyzed hydroformylation followed by an AAD-type reaction (AAD: Amides-Aldehydes-Dienophiles). In view of the availability of the substrates, the atom-efficiency of the overall process, and the convenient introduction of substituents in the cyclohexene ring, this method complements current methods for the preparation of polysubstituted cyclohexane derivatives. PMID:24888893

  20. Promoting effects of Se on Rh/SiO sub 2 catalysis for ethene hydroformylation

    SciTech Connect

    Izumi, Y.; Asakura, K.; Iwasawa, Y. )

    1991-12-01

    The authors have recently reported the promoting effect of Se on Rh/ZrO{sub 2} catalysis for ethene hydroformylation. The addition of Se electronically modified Rh metal sites around the Se atom to be relatively positive, judging from XPS data which revealed that the oxidation state of Se on Rh particles is {minus}2. This mechanism for the creation of positive metal sites is different from the mechanism induced by site segregation of cationic additives. From IR, isotope effects and TPD studies, Se was suggested to interact with CO and propanoyl intermediate. This interaction should not only be electronic but also geometric by the appropriate distance between Se and adsorbates on Rh sites. For hydroformylation or CO/H{sub 2} reaction on Rh, it has been reported that the activity and selectivity depend on the kind of supports. Support effects can be classified as follows: (1) change of metal particle size, (2) modification of the electronic structure of surface metal site, (3) SMSI effect, and (4) surface groups (for example, OH groups) which directly react or interact with reaction intermediates. Rh on SiO{sub 2} may have a different electronic structure near its Fermi level, and Se would have a different interaction with the Rh to play a different role as promoter as compared to the Rh/ZrO{sub 2} system. In the present paper they report the promoting effects of Se on Rh/SiO{sub 2} catalysis for ethene hydroformylation and the interaction of Se and Rh atoms by kinetics, FT-IR, XPS, and EXAFS in comparison with the case of Se/Rh/ZrO{sub 2}.

  1. Hydroformylation of 1-octene under atmospheric pressure catalyzed by rhodium carbonyl thiolate complexes tethered to silica

    SciTech Connect

    Gao, H.; Angelici, R.J.

    1998-07-06

    The silica-tethered rhodium thiolate complex catalysts Rh-S/SiO{sub 2} and Rh-S-P/SiO{sub 2} were prepared by the condensation of SiO{sub 2} with Rh{sub 2}[{mu}-S(CH{sub 2}){sub 3}Si(OCH{sub 3}){sub 3}]{sub 2}(CO){sub 4} (Rh-S) or Rh{sub 2}[{mu}-S(CH{sub 2}){sub 3}Si(OCH{sub 3}){sub 3}]{sub 2}[Ph{sub 2}P(CH{sub 2}){sub 3}Si(OC{sub 2}H{sub 5}){sub 3}]{sub 2}(CO){sub 2} (Rh-S-P). These tethered complex catalysts exhibit high activity for the hydroformylation of 1-octene in the presence of phosphine donor ligands under the mild conditions of 60 C and 1 atm. IR (DRIFT) spectral studies of the catalysts used indicate that tethered monorhodium dicarbonyl thiolate complexes of the type Rh(SR)(CO){sub 2}(PR{prime}{sub 3}) are the predominant species on the surface for the catalysts that have the highest hydroformylation activity. The catalysts are easily separated from the reaction mixtures, and the Rh-S/SiO{sub 2} catalyst maintains its activity through at least three cycles over a total period of 69 h, during which time there are 1273 (mol of aldehyde/mol of Rh) turnovers. Effects of the phosphine ligand and PR{prime}{sub 3}/Rh mole ratio on the hydroformylation rate, conversion, and chemo- and regioselectivity for aldehyde products were also investigated.

  2. Precise supramolecular control of selectivity in the Rh-catalyzed hydroformylation of terminal and internal alkenes.

    PubMed

    Dydio, Pawe?; Detz, Remko J; Reek, Joost N H

    2013-07-24

    In this study, we report a series of DIMPhos ligands L1-L3, bidentate phosphorus ligands equipped with an integral anion binding site (the DIM pocket). Coordination studies show that these ligands bind to a rhodium center in a bidentate fashion. Experiments under hydroformylation conditions confirm the formation of the mononuclear hydridobiscarbonyl rhodium complexes that are generally assumed to be active in hydroformylation. The metal complexes formed still strongly bind the anionic species in the binding site of the ligand, without affecting the metal coordination sphere. These bifunctional properties of DIMPhos are further demonstrated by the crystal structure of the rhodium complex with acetate anion bound in the binding site of the ligand. The catalytic studies demonstrate that substrate preorganization by binding in the DIM pocket of the ligand results in unprecedented selectivities in hydroformylation of terminal and internal alkenes functionalized with an anionic group. Remarkably, the selectivity controlling anionic group can be even 10 bonds away from the reactive double bond, demonstrating the potential of this supramolecular approach. Control experiments confirm the crucial role of the anion binding for the selectivity. DFT studies on the decisive intermediates reveal that the anion binding in the DIM pocket restricts the rotational freedom of the reactive double bound. As a consequence, the pathway to the undesired product is strongly hindered, whereas that for the desired product is lowered in energy. Detailed kinetic studies, together with the in situ spectroscopic measurements and isotope-labeling studies, support this mode of operation and reveal that these supramolecular systems follow enzymatic-type Michaelis-Menten kinetics, with competitive product inhibition. PMID:23802682

  3. Promoting effects of Se on Rh/ZrO sub 2 catalysis for ethene hydroformylation

    SciTech Connect

    Izumi, Y.; Asakura, K.; Iwasawa Y. )

    1991-02-01

    The positive effects of Se added to Rh/ZrO{sub 2} catalysts in ethene hydroformylation were studied from the viewpoints of promoter effects of electronegative atoms usually regarded as poisoning atoms as well as electronic interactions with both substrate metal and adsorbed species. Se-modified Rh/ZrO{sub 2} catalysts prepared by the reactive deposition of (CH{sub 3}){sub 2}Se or coimpregnation method using SeO{sub 2} were found to be active and selective for ethene hydroformylation. The Se addition promoted the formation of propanol rather than propanal, the propanol formation being increased more than 70 times at an optimum {number sign} Se/Rh ratio. The propanoyl intermediates were observed at ca. 1770 cm{sup {minus}1} and converted reversibly to propionate species (bridge and digentate) observed at 1425-1575 cm{sup {minus}1}. The ensemble of Se{sup 2{minus}}/Rh was suggested to promote CO adsorption and the insertion of CO to ethyl species, where there is an electronic interaction between Se{sup 2{minus}} and CO or propanoyl species. The isotope effects of D{sub 2} and {sup 13}C{sup 18}O showed the switchover of the rate-determining step for hydroformylation from the CO insertion on the Rh/ZrO{sub 2} catalysts to the dissociative adsorption of H{sub 2} on the Se-Rh/ZrO{sub 2} catalysts. The role of Se is discussed in relation with the reaction mechanism.

  4. Interception and characterization of alkyl and acyl complexes in rhodium-catalyzed hydroformylation of styrene.

    PubMed

    Nelsen, Eleanor R; Landis, Clark R

    2013-07-01

    Reaction of [Rh(H)(CO)2(BDP)] (BDP = bis(diazaphospholane)) with styrene at low temperatures enables detailed NMR characterization of four- and five-coordinate rhodium alkyl complexes [Rh(styrenyl)(CO)n(BDP)] presumed to be intermediates in rhodium-catalyzed hydroformylation. The five-coordinate acyl complexes [Rh(C(O)styrenyl)(CO)2(BDP)] are also observed and characterized. The equilibrium distribution of these species suggests an inversion of thermodynamic preference for branched vs linear species from the alkyl to the acyl stage. PMID:23786304

  5. Easily accessible and highly tunable bisphosphine ligands for asymmetric hydroformylation of terminal and internal alkenes.

    PubMed

    Xu, Kun; Zheng, Xin; Wang, Zhiyong; Zhang, Xumu

    2014-04-01

    An efficient methodology for synthesizing a small library of easily tunable and sterically bulky ligands for asymmetric hydroformylation (AHF) has been reported. Five groups of alkene substrates have been tested with excellent conversions, moderate-to-excellent regio- and enantioselectivities. Among the best result of the reported literature, application of ligand 1?c in the highly selective AHF of the challenging substrate 2,5-dihydrofuran yielded almost one isomer in up to 99?% conversion along with enantiomeric excesses (ee) of up to 92?%. Highly enantioselective AHF of dihydropyrrole substrates is achieved using the same ligand, with up to 95?%?ee and up to >1:50 ?-isomer/?-isomer ratio. PMID:24573699

  6. Revealing the mechanism of Rh(I)-catalyzed hydroformylation of 4-pyridylethene derivatives: DFT study

    NASA Astrophysics Data System (ADS)

    Luo, Xiaoling; Tang, Dianyong; Li, Ming

    A comprehensive theoretical investigation into the mechanism of 1-phenyl-1-(4-pyridyl)ethene hydroformylation, using a rhodium catalyst employing a nonlocal density functional method (B3LYP), was carried out. The calculated results show that it is strongly exothermic by >90 kJ/mol of the whole catalytic cycle, and the rate-limited step is H2 oxidative addition. The regioselectivity originates from olefin insertion into the Rh bond H bond. The predominant product is the regiospecifically 3-phenyl-3-(4-pyridal)propanal determined both thermodynamically and kinetically. These are in agreement with practicality experimental studies.

  7. Hydroformylation of ethylene via spontaneous cell reactions in the gas phase

    SciTech Connect

    Otsuka, Kiyoshi; Ando, Ten; Yamanaka, Ichiro

    1997-01-15

    A new method for the hydroformylation of ethylene using a gas cell composed of (C{sub 2}H{sub 4}, CO, cathode {vert_bar}H{sub 3}PO{sub 4} aq.{vert_bar} anode (Pt-black), H{sub 2}) has been examined at ca. 373 K and atmospheric pressure. Among many cathode electrocatalysts tested, H{sub 2}PtCl{sub 6} showed the highest selectivity and high activity for the formation of C{sub 2}H{sub 5}CHO. However, H{sub 2}PtCl{sub 6} did not catalyze the reaction at all under a gas mixture of C{sub 2}H{sub 4}, CO, and H{sub 2}. H{sub 2}PtCl{sub 6} was specifically active for the electrocatalytic hydroformylation by separating H{sub 2} from C{sub 2}H{sub 4} and CO with a H{sub 3}PO{sub 4}-electrolyte membrane. The addition of Na{sub 3}PO{sub 4} to the cathode enhanced the rate of C{sub 2}H{sub 5}CHO formation as well as the selectivity. The cell reaction does not require electrical energy input but takes place spontaneously and most efficiently under short-circuit conditions. The results from kinetic and electrochemical studies have suggested that the catalytic active species is the Pt{sup 2+}-chloride supported on the host graphite. A stronger coordination of CO compared to those of C{sub 2}H{sub 4} and hydride reduces both the hydrogenation and hydroformylation of C{sub 2}H{sub 4}. Therefore, a low partial pressure of CO and higher partial pressures of C{sub 2}H{sub 4} and H{sub 2} are recommended for the conversion of C{sub 2}H{sub 4}. The optimum temperature for the hydroformylation was 373 K. The results of transition response experiments have suggested a rapid reversible coordination of C{sub 2}H{sub 4} but a slow conversion of the precursor of C{sub 2}H{sub 5}CHO on Pt{sup 2+} the sites. A tentative reaction mechanism assuming the formations of ethyl-carbonyl, ethyl-carbonyl hydride and acyl-carbonyl Pt complexes has been proposed on the bases of the results in this work. 15 refs., 13 figs., 2 tabs.

  8. Domino-hydroformylation/aldol condensation catalysis: highly selective synthesis of ?,?-unsaturated aldehydes from olefins.

    PubMed

    Fang, Xianjie; Jackstell, Ralf; Franke, Robert; Beller, Matthias

    2014-10-01

    A general and highly chemo-, regio-, and stereoselective synthesis of ?,?-unsaturated aldehydes by a domino hydroformylation/aldol condensation reaction has been developed. A variety of olefins and aromatic aldehydes were efficiently converted into various substituted ?,?-unsaturated aldehydes in good to excellent yields in the presence of a rhodium phosphine/acid-base catalyst system. In view of the easy availability of the substrates, the high atom-efficiency, the excellent selectivity, and the mild conditions, this method is expected to complement current methodologies for the preparation of ?,?-unsaturated aldehydes. PMID:25179918

  9. Small bite-angle P-OP ligands for asymmetric hydroformylation and hydrogenation.

    PubMed

    Fernández-Pérez, Héctor; Benet-Buchholz, J; Vidal-Ferran, Anton

    2013-07-19

    A series of small bite-angle phosphine-phosphite (P-OP) ligands have been synthesized by a two-step method. The key intermediate was prepared by an unprecedented asymmetric carbonyl reduction of a phosphamide using the CBS (Corey-Bakshi-Shibata) catalyst. The topology of these ligands (a configurationally stable stereogenic carbon with two heteroatom substituents) and their small bite-angle (created by the close proximity of the two ligating groups to the metal center) together provide a rigid asymmetric environment around this center, enabling high stereoselectivity in hydroformylations and hydrogenations of standard substrates. PMID:23815635

  10. An infrared study of the Rh-Y zeolite related to activity for ethylene hydroformylation

    SciTech Connect

    Takahashi, Nobuo; Mijin, Akihiko; Suematsu, Hanzo; Shinohara, Shuri; Matsuoka, Hideki )

    1989-06-01

    Two types of CO-Rh species formed on the Rh-Y zeolite, Rh{sub 6}(CO){sub 16} and Rh{sup I}(CO){sub 2} were exposed to various atmospheres containing reaction components of ethylene hydroformylation. During exposure of Rh{sub 6}(CO){sub 16}/Y to C{sub 2}H{sub 4} + H{sub 2}, Rh{sub 6}(CO){sub 16} was decomposed and some CO molecules were converted into propionaldehyde. In the case of Rh{sup I}(CO){sub 2}/Y, only a very small decrease in IR bands due to Rh{sup I}(CO){sub 2} was observed, while the formation of propionaldehyde was not appreciable. The sample once exposed to C{sub 2}H{sub 4} + H{sub 2}, however, became active for ethylene hydroformylation. During exposure of Rh{sub 6}(CO){sub 16}/Y to a reaction mixture for ethylene hydroformylation, neither changes in the IR bands due to Rh{sub 6}(CO){sub 16} modification nor formation of propionaldehyde was observed. In the case of Rh{sup I}(CO){sub 2}/Y, almost no changes were observed in the bands due to Rh{sup I}(CO){sub 2}. However, a small amount of propionaldehyde was formed during the exposure, while the formation was not important compared with that on the Rh{sup I}(CO){sub 2}/Y once exposed to C{sub 2}H{sub 4} + H{sub 2}. The change in color of RH{sup I}(CO){sub 2}/Y from light yellow to gray was observed during the exposure to C{sub 2}H{sub 4} + H{sub 2} or C{sub 2}H{sub 4} + CO + H{sub 2}. The catalytic activity Rh-Y for ethylene hydroformylation was considerably enhanced by pretreatment of the fresh Rh-Y with H{sub 2}. The predominant rhodium species on the sample exposed to H{sub 2} at 393 K were found to be metallic rhodium by X-ray photoelectron spectroscopy.

  11. Paraformaldehyde and methanol as C1 ?feedstocks in metal-catalyzed C-C couplings of ?-unsaturated reactants: beyond hydroformylation.

    PubMed

    Sam, Brannon; Breit, Bernhard; Krische, Michael J

    2015-03-01

    Ruthenium-catalyzed reductive couplings of paraformaldehyde with dienes, alkynes, and allenes provide access to products of hydrohydroxymethylation that cannot be formed selectively under the conditions of hydroformylation. In certain cases, the regioselectivity of the C?C coupling can be inverted by using nickel catalysts. With iridium catalysts, methanol engages in redox-neutral regioselective hydrohydroxymethylations. PMID:25430585

  12. Homogeneous, single-phase hydroformylation of olefins using ionic phosphines and novel catalyst/product separation

    SciTech Connect

    Abatjoglou, A.G.; Peterson, R.R.; Bryant, D.R.

    1995-12-01

    A high efficiency low pressure hydroformylation process for higher molecular weight olefins has been developed using rhodium/ionic phosphine catalyst. Catalyst solubilization in the non-polar reactants and products is achieved using specialized solubilizing agents, such as N-methyl pyrrolidone (NMP), yielding single-phase systems. Separation of catalyst from product is induced by the addition of small amounts of water outside the hydroformylation reactor. Under the two-phase conditions, most of the catalyst components are found in the polar NMP/water phase, and the products (aldehydes, olefins, reaction byproducts) in a separate, non-polar, phase. The catalyst phase is recycled to the reactors after thorough drying to ensure a single homogeneous phase at reaction conditions. Traces of catalyst and solubilizing agent are effectively recovered from the product and recycled. A major advantage of this process, over water-based two-phase systems, is the high catalytic reactivities and concomitant high olefin efficiencies (>90%) which are achieved with olefins of low, water solubility.

  13. The rate-determining step in the rhodium-xantphos-catalysed hydroformylation of 1-octene.

    PubMed

    Zuidema, Erik; Escorihuela, Laura; Eichelsheim, Tanja; Carbó, Jorge J; Bo, Carles; Kamer, Paul C J; van Leeuwen, Piet W N M

    2008-01-01

    The rate-determining step in the hydroformylation of 1-octene, catalysed by the rhodium-Xantphos catalyst system, was determined by using a combination of experimentally determined (1)H/(2)H and (12)C/(13)C kinetic isotope effects and a theoretical approach. From the rates of hydroformylation and deuterioformylation, a small (1)H/(2)H isotope effect of 1.2 was determined for the hydride moiety of the rhodium catalyst. (12)C/(13)C isotope effects of 1.012(1) and 1.012(3) for the alpha-carbon and beta-carbon atoms of 1-octene were determined, respectively. Both quantum mechanics/molecular mechanics (QM/MM) and full quantum mechanics calculations were carried out on the key catalytic steps, for "real-world" ligand systems, to clarify whether alkene coordination or hydride migration is the rate-determining step. Our calculations (21.4 kcal mol(-1)) quantitatively reproduce the experimental energy barrier for CO dissociation (20.1 kcal mol(-1)) starting at the (bisphosphane)RhH(CO)(2) resting state. The barrier for hydride migration lies 3.8 kcal mol(-1) higher than the barrier for CO dissociation (experimentally determined trend approximately 3 kcal mol(-1)). The computed (1)H/(2)H and (12)C/(13)C kinetic isotope effects corroborate the results of the energy analysis. PMID:18061923

  14. Supported ionic liquid phase catalysis with supercritical flow.

    PubMed

    Hintermair, Ulrich; Zhao, Guoying; Santini, Catherine C; Muldoon, Mark J; Cole-Hamilton, David J

    2007-04-14

    Rapid hydroformylation of 1-octene (rates up to 800 h(-1)) with the catalyst remaining stable for at least 40 h and with very low rhodium leaching levels (0.5 ppm) is demonstrated when using a system involving flowing the substrate, reacting gases and products dissolved in supercritical CO(2) (scCO(2)) over a fixed bed supported ionic liquid phase catalyst. PMID:17389993

  15. Exchanging conformations of a hydroformylation catalyst structurally characterized using two-dimensional vibrational spectroscopy.

    PubMed

    Panman, Matthijs R; Vos, Jannie; Bocoki?, Vladica; Bellini, Rosalba; de Bruin, Bas; Reek, Joost H N; Woutersen, Sander

    2013-12-16

    Catalytic transition-metal complexes often occur in several conformations that exchange rapidly (hydroformylation catalyst (xantphos)Rh(CO)2H using two-dimensional vibrational spectroscopy, a method that can be applied to any catalyst provided that the exchange between its conformers occurs on a time scale of a few picoseconds or slower. We find that, in one of the conformations, the OC-Rh-CO angle deviates significantly from the canonical value in a trigonal-bipyramidal structure. On the basis of complementary density functional calculations, we ascribe this effect to attractive van der Waals interaction between the CO and the xantphos ligand. PMID:24256078

  16. A selective functionalized mesoporous silica-supported Rh catalyst for effective 1-octene hydroformylation.

    PubMed

    Jeon, Jong-Ki; Ko, Young Soo; Yim, Jin-Heong

    2013-04-01

    Through different functionalization methods, three kinds of Rh-immobilized mesoporous silicas have successfully been prepared to investigate catalytic behavior, including yield and the linear/branched ratio of aldehyde (L/B) in 1-octene hydroformylation. A conventional post grafting method and two kinds of selective bifunctionalized methods for modification of the mesoporous silica have been applied for this purpose. A relatively high L/B (> 2.0) was effectively achieved using Rh-immobilized inner pores in the MCM-41 support due to the confinement effects of the Rh complex in the nanospace. Moreover, the Rh-immobilized MCM-41 catalyst, passivated with trimethylchlorosilane (TMCS) only on the external surface, showed fairly good yields of the aldehyde (> 40%). PMID:23763205

  17. Organic chemistry. Rh-catalyzed C-C bond cleavage by transfer hydroformylation.

    PubMed

    Murphy, Stephen K; Park, Jung-Woo; Cruz, Faben A; Dong, Vy M

    2015-01-01

    The dehydroformylation of aldehydes to generate olefins occurs during the biosynthesis of various sterols, including cholesterol in humans. Here, we implement a synthetic version that features the transfer of a formyl group and hydride from an aldehyde substrate to a strained olefin acceptor. A Rhodium (Xantphos)(benzoate) catalyst activates aldehyde carbon-hydrogen (C-H) bonds with high chemoselectivity to trigger carbon-carbon (C-C) bond cleavage and generate olefins at low loadings (0.3 to 2 mole percent) and temperatures (22° to 80°C). This mild protocol can be applied to various natural products and was used to achieve a three-step synthesis of (+)-yohimbenone. A study of the mechanism reveals that the benzoate counterion acts as a proton shuttle to enable transfer hydroformylation. PMID:25554782

  18. Rh-Catalyzed C–C Bond Cleavage by Transfer Hydroformylation

    PubMed Central

    Murphy, Stephen K.; Park, Jung-Woo; Cruz, Faben A.; Dong, Vy M.

    2015-01-01

    The dehydroformylation of aldehydes to generate olefins occurs during the biosynthesis of various sterols, including cholesterol in humans. Here, we implement a synthetic version that features the transfer of a formyl group and hydride from an aldehyde substrate to a strained olefin acceptor. A Rh(Xantphos)(benzoate) catalyst activates aldehyde C–H bonds with high chemoselectivity to trigger C–C bond cleavage and generate olefins at low loadings (0.3 to 2 mol%) and temperatures (22 to 80 °C). This mild protocol can be applied to various natural products and was used to achieve a three step synthesis of (+)-yohimbenone. A study of the mechanism reveals that the benzoate counterion acts as a proton-shuttle to enable transfer hydroformylation. PMID:25554782

  19. Experimental and modeling study of hydrogenation using deuterium step transient response during ethylene hydroformylation

    SciTech Connect

    Brundage, M.A.; Chuang, S.S.C.

    1996-11-01

    Deuterium isotopic step tracing combined with in situ infrared (IR) spectroscopy was utilized to study and model the hydrogenation steps in ethylene hydroformylation on 4 wt% Rh/SiO{sub 2} at 483-573 K and 0.1 MPa. The difference in residence times between H{sub 2} and D{sub 2}, as well as propionaldehyde and deuterated propionaldehyde to the step switch from H{sub 2} to D{sub 2} and D{sub 2} to H{sub 2} during ethylene hydroformylation reflects the presence of an isotope effect for H{sub 2}/D{sub 2} chemisorption and propionaldehyde formation. Compartment modeling of H{sub 2}/D{sub 2} responses and qualitative comparison of propionaldehyde and deuterated propionaldehyde responses unravel the presence of a normal equilibrium isotope effect for H{sub 2}/D{sub 2} chemisorption and a normal kinetic isotope effect for hydrogenation/deuteration of adsorbed acyl species. In situ IR coupled with deuterium transient responses shows that the reverse spillover of deuterium from Si-OD participates in the deuteration of adsorbed acyl species, suggesting that the site for deuteration of the adsorbed species, suggesting that the site for deuteration of the adsorbed acyl species is located near the Rh and SiO{sub 2} interface. Significant difference in the deuterated ethane and propionaldehyde responses suggests the different nature of either adsorbed hydrogen/deuterium or the active site for hydrogenation/deuteration of adsorbed ethyl and acyl species. 31 refs., 12 figs., 6 tabs.

  20. Effect of phosphines on the thermodynamics of the cobalt catalyzed hydroformylation system.

    SciTech Connect

    Klingler, R. J.; Chen, M. J.; Rathke, J. W.; Kramarz, K. W.; Chemical Engineering; BASF Corp.

    2007-01-01

    Thermodynamic parameters relevant to the phosphine-modified cobalt hydroformylation reaction are reported. Equilibrium constants for the hydrogenation of Co{sub 2}(CO){sub 6}L{sub 2} to yield HCo(CO){sub 3}L were determined using in situ {sup 1}H and {sup 31}P NMR spectroscopy between 75 and 175 C for various solvents and phosphine ligands. Special emphasis was placed on n-Bu{sub 3}P, as this ligand is prototypical of the Shell hydroformylation process. The resultant van't Hoff plots yield the enthalpy and entropy change (H = 7.0 {+-} 0.4 kcal/mol and {Delta}S = 2 {+-} 1 cal/mol {center_dot} K) for the case of L = n-Bu{sub 3}P in benzene solvent. These parameters were found to be relatively insensitive to changes in the solvent, suggesting that the hydride product is not very polar. Even for isobutyl alcohol solvent, the resultant enthalpy and entropy changes (H = 5.8 {+-} 0.4 kcal/mol and S = -2 {+-} 1 cal/mol {center_dot} K) were found to be similar to those obtained in benzene and dioxane. Analysis of the {sup 31}P NMR line widths allows rigorous lower limits to be established for the catalytically relevant Co-Co and Co-H bond energies in the case of L = n-Bu{sub 3}P (Co-Co 23 kcal/mol and Co-H 60 kcal/mol) relative to the previously reported values for the case of L = CO (Co-Co = 19 {+-} 2 kcal/mol and Co-H = 59 {+-} 1 kcal/mol).

  1. Highly Efficient Heterogeneous Hydroformylation over Rh-Metalated Porous Organic Polymers: Synergistic Effect of High Ligand Concentration and Flexible Framework.

    PubMed

    Sun, Qi; Dai, Zhifeng; Liu, Xiaolong; Sheng, Na; Deng, Feng; Meng, Xiangju; Xiao, Feng-Shou

    2015-04-22

    A series of diphosphine ligand constructed porous polymers with stable and flexible frameworks have been successfully synthesized under the solvothermal conditions from polymerizing the corresponding vinyl-functionalized diphosphine monomers. These insoluble porous polymers can be swollen by a wide range of organic solvents, showing similar behavior to those of soluble analogues. Rather than just as immobilizing homogeneous catalysts, these porous polymers supported with Rh species demonstrate even better catalytic performance in the hydroformylations than the analogue homogeneous catalysts. The sample extraordinary performance could be attributed to the combination of high ligand concentration and flexible framework of the porous polymers. Meanwhile, they can be easily separated and recycled from the reaction systems without losing any activity and selectivity. This excellent catalytic performance and easy recycling heterogeneous catalyst property make them be very attractive. These diphosphine ligand constructed porous polymers may provide new platforms for the hydroformylation of olefins in the future. PMID:25848868

  2. DFT Study of the Ethylene Hydroformylation Catalytic Cycle Employing a HRh(PH3)2(CO) Model Catalyst

    SciTech Connect

    Decker, Stephen A.; Cundari, Thomas R.

    2001-06-25

    The potential energy hypersurface for ethylene hydroformylation catalyzed by HRh(PH3)2- (CO) was mapped out at the CCSD(T)//B3LYP and B3LYP//B3LYP levels of theory using effective core potentials. Combining the results obtained for each elementary step there are a number of possible pathways for the hydroformylation catalytic cycle, originating from the trans (2a) and cis (2b) isomers of the active catalyst. At both levels of theory employed, a preference was predicted for the pathways originating from the trans isomer of the active catalyst, 2a. The alternative pathways originating from the cis isomer, 2b, were discounted because of the large activation barriers predicted for the two migratory insertion reactions, arising from unfavorable interactions between the equatorial phosphine ligands and the migrating axial ligand.

  3. Preparation of phosphine-functionalized polystyrene stars by metal catalyzed controlled radical copolymerization and their application to hydroformylation catalysis.

    PubMed

    Cardozo, Andrés F; Manoury, Eric; Julcour, Carine; Blanco, Jean-François; Delmas, Henri; Gayet, Florence; Poli, Rinaldo

    2013-07-01

    Well defined star copolymers have been prepared by copper-catalyzed atom transfer radical copolymerization of styrene and styryldiphenylphosphine starting from a modified Boltorn™ H30 multifunctional initiator. These polymers and an analogue obtained by debromination of the arm ends with nBu3SnH have been used in combination with [Rh(acac)(CO)2] for the homogeneous phase hydroformylation of 1-octene. PMID:23487263

  4. Synthesis and application of tetraphosphane ligands in rhodium-catalyzed hydroformylation of terminal olefins: high regioselectivity at high temperature.

    PubMed

    Yu, Shichao; Zhang, Xiaowei; Yan, Yongjun; Cai, Chaoxian; Dai, Liyan; Zhang, Xumu

    2010-04-26

    A new class of substituted tetraphosphane ligands has been developed and applied in the rhodium-catalyzed regioselective hydroformylation of terminal olefins. The high regioselectivity (linear selectivity is above 97 % for 1-octene and 1-hexene) at high temperature (140 degrees C) shown by these tetraphosphane ligands is remarkable considering the low regioselectivity commonly observed under similar reaction conditions when other bisphosphane analogues are used. The steric and electronic effects of substituents on the diarylphosphane moiety have also been examined. PMID:20340113

  5. Study of hydroformylation of formaldehyde in the presence of rhodium catalysts by in situ IR spectroscopy and the kinetic technique

    SciTech Connect

    Ezhova, N.N.; Korneeva, G.A.; Kurkin, V.I.

    1995-06-01

    Carbonylrhodium complexes formed during hydroformylation of CH{sub 2}O from various rhodium precursors were investigated by in situ IR spectroscopy. It was found that under the conditions of the hydroformylation of CH{sub 2}O in N,N-dimethylacetamide (DMAA), RhH(CO)(PPh{sub 3}){sub 3}, RhCl(CO)(PPh{sub 3}){sub 2}, RhCl(PPh{sub 3}), RhCl(CO)(PBu{sub 3}){sub 2}, and (RhCl(CO){sub 2}){sub 2} form complex systems that necessarily contain anionic complexes, (Rh(CO){sub 2}L{sub x}(DMAA){sub y}){sup {minus}}(L=PPh{sub 3}, PBu{sub 3},x=1 to 2, y= 1 to 0; (Rh(CO){sub 4}){sup {minus}}). The participation of ionic structures in the hydroformylation of CH{sub 2}O, most likely, in the step of the activation of CH{sub 2}O, was proven by kinetic techniques.

  6. Expanded scope of supported aqueous phase catalysis: Efficient rhodium-catalyzed hydroformylation of {alpha},{beta}-unsaturated esters

    SciTech Connect

    Fremy, G.; Carpentier, J.F.; Mortreux, A.

    1996-09-01

    The use of supported aqueous-phase (SAP) catalysts for the rhodium-based hydroformylation of methyl acrylate leads under optimal conditions to much higher activities than those observed under comparable homogeneous and biphasic conditions. The results obtained with a series of acrylic esters are found to be dependent on the water content of the solid support and on the solubility of the functionalized olefin in water. For soluble organic reactants, like methyl acrylate, optimal activities are obtained for fully filled pore volume materials. For less soluble organic reactants, like butyl acrylate, hydroformylations are best achieved with a lower degree of pore filling, strictly dependent on the nature of the functionalized olefin. It is assumed that the reaction of hydrophilic olefins occurs mainly in the homogeneous water film dispersed over the solid support, whilst that of lipophilic olefins takes place at the interface between the organic phase and the aqueous film. The effects of temperature and the nature of the solid support are reported. Experiments are described that indicate that the surface area and the chemical nature of the solid play a major role on the activity of the SAP catalyst, whilst the pore diameter has almost no influence. However, a decrease in the activity of methyl acrylate hydroformylation was observed upon recycling of the SAPC materials, which was attributed to the leaching of rhodium into the organic phase and the gradual dehydration of silica. 24 refs., 8 figs., 3 tabs.

  7. Computational investigation of enantio- and regioselectivity of rhodium-catalyzed asymmetric hydroformylation of vinyl formate with CHIRAPHOS-type ligand

    NASA Astrophysics Data System (ADS)

    Luo, Xiaoling; Tang, Dianyong; Li, Ming

    The potential energy profile for Rh-catalyzed asymmetric hydroformylation of vinyl formate is mapped out using a nonlocal density functional method (B3LYP). This study focuses on the enantio- and regioselectivity of asymmetric hydroformylation. All the structures are optimized at the B3LYP/6-31G(d,p) level(LANL2DZ(d) for Rh, P). As illustrated by computation, the olefin insertion step is irreversible because of higher activation free energy of the reverse reaction than that of forward reaction, so it is the determining step for both the regioselectivity and enantioselectivity in asymmetric hydroformylation. The lowest activation free energy in vinyl insertion is the path 2a ? TS1a (?G? = 47.92 kJ/mol), giving rise to the preferred product as (S)-1-formylenthyl formate. Throughout the catalytic cycle, the H2 oxidative addition has the highest activation free energy, 77.24 kJ/mol, so it is the rate-limiting step for the whole catalytic cycle. The calculation results are in agreement with many experiment investigations.

  8. Engineering aspects of gas-liquid catalytic reactions

    SciTech Connect

    Carra, S.; Santacesaria, E.

    1980-01-01

    A review of factors which affect selectivity and product yield in gas absorption with liquid-phase catalytic reaction and which must be considered in reactor design covers the chemistry and kinetics of homolytic and heterolytic oxidation reactions in the production, e.g., of acetic acid from butane catalyzed by cobalt acetate in a sparged reactor, hydroformylation, carbonylation, hydrogenation, and acid-base catalysis; mass transfer, phase equilibria, and the effect of the chemical reaction on mass transfer rates in gas-liquid reaction systems; modeling of reactors in which the gas is the dispersed phase, including stirred tank and bubble column reactors; and modeling of distillation with catalytic reaction.

  9. Enantioselective hydroformylation by a Rh-catalyst entrapped in a supramolecular metallocage.

    PubMed

    García-Simón, Cristina; Gramage-Doria, Rafael; Raoufmoghaddam, Saeed; Parella, Teodor; Costas, Miquel; Ribas, Xavi; Reek, Joost N H

    2015-02-25

    Regio- and enantioselective hydroformylation of styrenes is attained upon embedding a chiral Rh complex in a nonchiral supramolecular cage formed from coordination-driven self-assembly of macrocyclic dipalladium complexes and tetracarboxylate zinc porphyrins. The resulting supramolecular catalyst converts styrene derivatives into aldehyde products with much higher chiral induction in comparison to the nonencapsulated Rh catalyst. Spectroscopic analysis shows that encapsulation does not change the electronic properties of the catalyst nor its first coordination sphere. Instead, enhanced enantioselectivity is rationalized by the modification of the second coordination sphere occurring upon catalyst inclusion inside the cage, being one of the few examples in achieving an enantioselective outcome via indirect through-space control of the chirality around the catalyst center. This effect resembles those taking place in enzymatic sites, where structural constraints imposed by the enzyme cavity can impart stereoselectivities that cannot be attained in bulk. These results are a showcase for the future development of asymmetric catalysis by using size-tunable supramolecular capsules. PMID:25632976

  10. Potent inhibitors of malarial aspartic proteases, the plasmepsins, by hydroformylation of substituted 7-azanorbornenes.

    PubMed

    Aureggi, Valentina; Ehmke, Veronika; Wieland, Joerg; Schweizer, W Bernd; Bernet, Bruno; Bur, Daniel; Meyer, Solange; Rottmann, Matthias; Freymond, Céline; Brun, Reto; Breit, Bernhard; Diederich, François

    2013-01-01

    The increasing prevalence of multidrug-resistant strains of the malarial parasite Plasmodium falciparum requires the urgent development of new therapeutic agents with novel modes of action. The vacuolar malarial aspartic proteases plasmepsin (PM) I, II, and IV are involved in hemoglobin degradation and play a central role in the growth and maturation of the parasite in the human host. We report the structure-based design, synthesis, and in vitro evaluation of a new generation of PM inhibitors featuring a highly decorated 7-azabicyclo[2.2.1]heptane core. While this protonated central core addresses the catalytic Asp dyad, three substituents bind to the flap, the S1/S3, and the S1' pockets of the enzymes. A hydroformylation reaction is the key synthetic step for the introduction of the new vector reaching into the S1' pocket. The configuration of the racemic ligands was confirmed by extensive NMR and X-ray crystallographic analysis. In vitro biological assays revealed high potency of the new inhibitors against the three plasmepsins (IC(50) values down to 6?nM) and good selectivity towards the closely related human cathepsins D and E. The occupancy of the S1' pocket makes an essential contribution to the gain in binding affinity and selectivity, which is particularly large in the case of the PM?IV enzyme. Designing non-peptidic ligands for PM II is a valid route to generate compounds that inhibit the entire family of vacuolar plasmepsins. PMID:23161835

  11. Stable crystalline annulated diaminocarbenes: coordination with rhodium(I), iridium(I) and catalytic hydroformylation studies.

    PubMed

    Dastgir, Sarim; Coleman, Karl S; Cowley, Andrew R; Green, Malcolm L H

    2009-09-21

    Stable annulated diaminocarbene ligands 7,9-bis(2,4,6-trimethylphenyl)-6b,9a-dihydroace naphtha[1,2-d]imidazolin-2-ylidene and 7,9-bis(2,6-diisopropylphenyl)-6b,9a-dihydroacenaphtho[1,2-d]imidazolin-2-ylidene; designated as (BIAN-SIMes, 5a,) and (BIAN-SIPr, 5b), respectively, have been prepared. The base dependent decomposition of imidazolinium salts via ring opening at the backbone was also observed. The corresponding rhodium(I) and iridum(I) complexes (4-1,5-COD)M(BIAN-SIMes)Cl and (4-1,5-COD)M(BIAN-SIPr)Cl; M= Rh (6a, 6b) and Ir (7a, 7b) have been synthesised by the reaction of free carbene with [M(4-1,5-COD)(-Cl)]2; where M= Rh, Ir. The cationic Ir(I) complexes [(4-1,5-COD)Ir(BIAN-SIMes)Py]BF4 8a and [(4-1,5-COD)Ir(BIAN -SIPr)Py]PF6 8b have also been synthesised. Compounds 4b, 5a, 6a, 6b, 7b and 8b have been structurally characterised. The catalytic activities for the rhodium(I) complexes 6a and 6b were evaluated for the hydroformylation of 1-octene. PMID:20449164

  12. Regioselective hydroformylation of cylic vinyl and allyl ethers with rhodium catalysts. Crucial influence of the size of the phosphorous cocatalyst

    SciTech Connect

    Polo, A.; Claver, C.; Castillon, S.

    1992-11-01

    The authors have explored the possibilities offered by the modification of thiolato bridges in dinuclear rhodium complexes on the selective hydroformylation of cylic vinyl and allyl ethers. The dinuclear complex [Rh{sub 2}({mu}-S(CH{sub 2}){sub 3}NMe{sub 2}){sub 2}(cod){sub 2}] (cod = 1,5-cyclooctadiene) has been prepared, and its reactivity with CO, phospines, and phosphites has been investigated. The complex crystallizes in the monoclinic space group C2/c with Z = 8, {alpha} = 22.543 (4) A, B = 12.040 (2) A, c = 21.547 (3) A, and {Beta} = 98.77 (1){degrees}. For the determination of the structure 4091 unique reflections were used, and the final refinement gave R = 4.1% and R{sub w} = 4.4%. The molecular structure reveals that the two rhodium atoms are bridged by the two thiolato ligands, and the cyclooctadiene completes the coordination of the metal atoms. The amine groups are not bonded to the rhodium. The dinuclear complex has been used in the hydroformylation of 2,3-di-hydrofuran, 2,5-dihydrofuran, 3,4-dihydro-2H-pyran or 3,6-dihydro-2H-pyran was tetrahydropyran-2-carbaldehyde. A systematic study of the influence of the reaction parameters on the selectivity of the hydroformylation of 2,3-dihydroformylation of 3,4-dihydro-2H-pyran or 3,6-dihydro-2H-pyran was tetrahydropyran-2-carbaldehyde. A systematic study of the influence of the reaction parameters on the selectivity of the hydroformylation of 2,3-dihydrofuran and 2,5-dihydrofuran was undertaken. The study allowed the rationalization of the observed selectivity and the optimization of the yields and regioselectivities. Thus, by modification of the reaction parameters, tetrahydrofuran-3-carbaldehyde was obtained in quantitative yields from 2,5-dihydrofuran and tetrahydrofuran-2-carbaldehyde can be prepared from either 2,3-dihydrofuran or 2,5-dihydrofuran in approximately 75% yield. 33 refs., 3 figs., 9 tabs.

  13. Development of a ruthenium/phosphite catalyst system for domino hydroformylation-reduction of olefins with carbon dioxide.

    PubMed

    Liu, Qiang; Wu, Lipeng; Fleischer, Ivana; Selent, Detlef; Franke, Robert; Jackstell, Ralf; Beller, Matthias

    2014-06-01

    An efficient domino ruthenium-catalyzed reverse water-gas-shift (RWGS)-hydroformylation-reduction reaction of olefins to alcohols is reported. Key to success is the use of specific bulky phosphite ligands and triruthenium dodecacarbonyl as the catalyst. Compared to the known ruthenium/chloride system, the new catalyst allows for a more efficient hydrohydroxymethylation of terminal and internal olefins with carbon dioxide at lower temperature. Unwanted hydrogenation of the substrate is prevented. Preliminary mechanism investigations uncovered the homogeneous nature of the active catalyst and the influence of the ligand and additive in individual steps of the reaction sequence. PMID:24811949

  14. Domino Rh-catalyzed hydroformylation-double cyclization of o-amino cinnamyl derivatives: applications to the formal total syntheses of physostigmine and physovenine.

    PubMed

    Chiou, Wen-Hua; Kao, Chien-Lun; Tsai, Jui-Chi; Chang, Yun-Man

    2013-09-25

    A parallel, versatile and efficient route to synthesis of pyrrolidinoindoline and tetrahydrofuranoindoline alkaloids from cinnamyl derivatives has been developed, featuring a domino Rh-catalyzed hydroformylation-double cyclization sequence. This method can be applied to the syntheses of anti-Alzheimer drugs such as physostigmine and physovenine. PMID:23926596

  15. Tandem decarboxylative hydroformylation-hydrogenation reaction of ?,?-unsaturated carboxylic acids toward aliphatic alcohols under mild conditions employing a supramolecular catalyst system.

    PubMed

    Diab, Lisa; Gellrich, Urs; Breit, Bernhard

    2013-10-28

    A new atom economic catalytic method for a highly chemoselective reduction of ?,?-unsaturated carboxylic acids to the corresponding saturated alcohols under mild reaction conditions, compatible with a wide range reactive functional groups, is reported. The new methodology consists of a novel tandem decarboxylative hydroformylation/aldehyde reduction sequence employing a unique supramolecular catalyst system. PMID:24022335

  16. Synthesis of the tetracyclic skeleton of the Lycopodium alkaloid lycopladine H via a pivotal double hydroformylation/intramolecular reductive amination sequence.

    PubMed

    Chauhan, Pradeep S; Sacher, Joshua R; Weinreb, Steven M

    2015-02-20

    A synthesis of the complete tetracyclic framework of the structurally unique Lycopodium alkaloid lycopladine H has been accomplished using a strategy involving a double alkene hydroformylation/intramolecular reductive amination to form the azocane and spiro-piperidine moieties of the natural product. PMID:25658603

  17. Encapsulated transition metal catalysts comprising peripheral Zn(II)salen building blocks: template-controlled reactivity and selectivity in hydroformylation catalysis.

    PubMed

    Kleij, Arjan W; Lutz, Martin; Spek, Anthony L; van Leeuwen, Piet W N M; Reek, Joost N H

    2005-08-01

    Encapsulated phosphane ligands can be easily constructed through coordinative interactions between Zn(II)-salphen complexes and pyridylphosphane templates; the template has a pronounced impact on the catalyst structure and consequently on the performance in the hydroformylation of 1-octene. PMID:16027903

  18. Scalable and chromatography-free synthesis of 2-(2-formylalkyl)arenecarboxylic acid derivatives through the supramolecularly controlled hydroformylation of vinylarene-2-carboxylic acids.

    PubMed

    Dydio, Pawe?; Reek, Joost N H

    2014-05-01

    This protocol describes how to prepare 2-(2-formylalkyl)-arenecarboxylic acid derivatives, common building blocks for the synthesis of various valuable chemicals (e.g., anti-obesity and Alzheimer's disease treatment pharmaceuticals), by using the fully regioselective hydroformylation of vinyl arene derivatives. This catalytic reaction proceeds cleanly with 100% regioselectivity and chemoselectivity. The procedure is reliably scalable and can be efficiently conducted on a multigram scale. The analytically pure product is easily isolated with a nearly quantitative yield by using a simple acid-base extraction workup and avoids any tedious chromatography. This protocol details the synthesis of a bisphosphite ligand (L1) that is a pivotal element of the catalytic system used, Rh(acac)(CO)2 with ligand L1, starting from commercial building blocks. The protocol also describes a general procedure for the preparative hydroformylation of vinylarene-2-carboxylic acid derivatives to 2-formylalkylarene products, providing a representative example for the hydroformylation of 2-vinylbenzoic acid (1a) to 2-(3-oxopropane)-benzoic acid (2a). The synthesis of L1 (six chemical reactions) uses 2-nitrophenylhydrazine, 4-benzyloxybenzoylchloride and (S)-binol, and takes 5-7 working days. The actual hydroformylation reaction of each vinyl arene derivative takes ?4 h of active effort over a period of 1-3 d. PMID:24762785

  19. Process for the hydroformylation of sulfur-containing thermally cracked petroleum residue and novel products thereof

    SciTech Connect

    Oswald, A.A.; Bhatia, R.N.; Mozeleski, E.J.; Glivicky, A.P.; Brueggeman, B.G.; Hooten, J.R.; Smith, C.M.; Hsu, C.S.

    1991-07-09

    This patent describes a hydroformylation-hydrogenation process comprising reacting an olefinic cracked petroleum distillate feed, produced from petroleum residue by high temperature thermal cracking, and containing C{sub 5} to C{sub 35}-1-n-alkyl olefins as the major type of olefin components, and organic sulfur compounds in concentrations exceeding 0.1% sulfur. It comprises at first with carbon monoxide and hydrogen at temperatures between about 50 and 250{degrees} C and pressures in the range of 50 to 6000 psi; in the presence of a Group VIII transition metal carbonyl complex catalyst in effective amounts to produce aldehydes of a semilinear character having an average of less than one alkyl branch per molecule and 20% by weight or more linear isomers, then with molecular hydrogen at temperatures between 100 and 250{degrees} C and pressures between 200 psi and 5000 psi (13.6 and 340 atm) in the presence of a hydrogenation catalyst in effective amounts the catalyst being sulfur resistant cobalt, molybdenum, nickel, or tungsten or a sulfide thereof to produce the corresponding alcohols of a semilinear character having an average of less than one alkyl branch per molecule and 20% by weight or more linear isomers, then with molecular hydrogen at temperatures between 100 and 250{degrees} C and pressures between 200 psi and 5000 psi (13.6 and 340 atm) in the presence of a hydrogenation catalyst in effective amounts the catalyst being sulfur resistant cobalt, molybdenum, nickel, or tungsten or a sulfide thereof to produce the corresponding alcohols of a semilinear character having an average of less than one alkyl branch per molecule.

  20. Transient infrared study of methanation and ethylene hydroformylation over Rh/SiO[sub 2] catalysts

    SciTech Connect

    Balakos, M.W.; Chuang, S.S.C.; Srinivas, G. )

    1993-03-01

    Determination of reactivity and surface coverage of intermediates has been a challenging goal in fundamental research of heterogeneous catalysis. First Happel et al. and later Biloen and co-workers employed the use of a transient rate tracer method for the determination of the intrinsic rate constant, k, and the fractional surface coverage, [Theta], of intermediates for steady-state carbon monoxide hydrogenation. The method was further developed and termed steady-state isotopic transient kinetic analysis (SSITKA) by Goodwin and co-workers. SSITKA is a transient method for the investigation of kinetics and mechanism of heterogeneous catalysis under steady-state conditions. The approach involves an abrupt switch from an inlet reactant species to a corresponding isotopically labeled species. The advantage of SSITKA from other transient methods is that the chemical environment of the catalyst surface does not vary with the transient state of the isotopic tracer, yielding tracer response curves for the determination of k and [Theta]. The method has been applied in the investigation of the mechanism of methanation, Fischer-Tropsch synthesis, ammonia synthesis, and partial oxidation of methane. In situ infrared absorption spectroscopy (IR) allows for the direct observation of absorbed species under reaction conditions. Incorporation of in situ IR spectroscopy with SSITKA may provide information on the surface coverages of IR observable species under reaction conditions and has the potential for distinguishing between reaction intermediates and surface absorbed spectator species. This paper reports the use of IR combined with SSITKA to study methanation and ethylene hydroformylation on Rh/SiO[sub 2] at 513 K and 0.1 MPa. 20 refs., 3 figs.

  1. Asymmetric hydroformylation catalyzed by RhH(CO)?[(R,S)-Yanphos]: mechanism and origin of enantioselectivity.

    PubMed

    Lei, Ming; Wang, Zhidong; Du, Xiaojie; Zhang, Xin; Tang, Yanhui

    2014-10-01

    Asymmetric hydroformylation (AHF) catalyzed by transition metal (TM) complexes bearing chiral phosphorus ligands is one of the most powerful synthetic ways that could provide chiral aldehydes directly from alkenes and syngas in one step. Experiments have proved the efficiency of Rh catalyst with hybrid phosphorus ligands owning two different phosphorus moieties in AHF. Herein the origin of enantioselectivity of AHF catalyzed by RhH(CO)2[(R,S)-Yanphos] was studied at M06/BSI level using the density functional theory (DFT) method to unveil a fundamental understanding on factors contributing to the efficiency in AHF. The alkene insertion step is supposed to be the chirality-determining step in the whole catalytic cycle of the Rh-Yanphos system. Four possible pathways of styrene (Sub1) insertion step (pathways R1, S1, R2, and S2) were discussed; the calculated results indicate that pathways R1 and S2 are proposed to be two dominant alkene insertion pathways and that styrene tends to adopt apical coordination mode (A mode) to Rh center in pathways R1 and S2 compared to equatorial coordination mode (E mode) in pathways R2 and S1. The enantioselectivity of AHFs of ten alkene substrates (CH2?CH-R, R?Ph, C(?O)OCH3, Ph-(p)-Me, Ph-(p)-OMe, Ph-(p)-(i)Bu, Ph-(p)-F, Ph-(p)-Cl, Ph-(o)-F, OC(?O)-Ph and O-Ph, corresponding alkenes are abbreviated as Sub1 to Sub10, respectively) were also investigated. The predicted chiralities agree well with experimental results. The present work suggests that the relative stabilities of coordination modes (A/E mode) of alkene to 2 (RhH(CO)[(R,S)-Yanphos]) might be of importance in the enantioselectivity of AHF catalyzed by Rh-Yanphos. PMID:24735053

  2. Enantiopure narrow bite-angle P-OP ligands: synthesis and catalytic performance in asymmetric hydroformylations and hydrogenations.

    PubMed

    Fernández-Pérez, Héctor; Benet-Buchholz, Jordi; Vidal-Ferran, Anton

    2014-11-17

    Herein is reported the preparation of a set of narrow bite-angle P-OP ligands the backbone of which contains a stereogenic carbon atom. The synthesis was based on a Corey-Bakshi-Shibata (CBS)-catalyzed asymmetric reduction of phosphomides. The structure of the resulting 1,1-P-OP ligands, which was selectively tuned through adequate combination of the configuration of the stereogenic carbon atom, its substituent, and the phosphite fragment, proved crucial for providing a rigid environment around the metal center, as evidenced by X-ray crystallography. These new ligands enabled very good catalytic properties in the Rh-mediated enantioselective hydrogenation and hydroformylation of challenging and model substrates (up to 99?%?ee). Whereas for asymmetric hydrogenation the optimal P-OP ligand depended on the substrate, for hydroformylation, a single ligand was the highest-performing one for almost all studied substrates: it contains an R-configured stereogenic carbon atom between the two phosphorus ligating groups, and an S-configured 3,3'-diphenyl-substituted biaryl unit. PMID:25335770

  3. Octene hydroformylation by using rhodium complexes tethered onto selectively functionalized mesoporous silica and in-situ high pressure IR study

    SciTech Connect

    Song, Ki-Chang; Baek, Ji Yeon; Bae, Jung A.; Yim, Jin-Heong; Ko, Young Soo; Kim, Do Heui; Park, Young-Kwon; Jeon, Jong Ki

    2011-04-30

    SBA-15-based heterogeneous catalysts were applied to 1-octene hydroformylation. The turn over frequency over SBA-15/?-aminopropylmethyldimethoxysilane(AEAPMDMS)/Rh catalyst with triphenylphosphine (TPP) ligand prepared by conventional post grafting method was higher than that of the homogeneous catalyst, (Rh(CH3COO)2)2 with TPP. The SBA-15/AEAPMDMS/Rh catalyst can be easily recycled without rhodium loss. The molar ratio of linear to branched nonyl aldehydes was remarkably enhanced over the heterogeneous catalysts. The selectively functionalized rhodium catalyst (SBA-15/Ph2Si(OEt)2/AEAPMDMS/Rh), in which rhodium was selectively tethered intra-pore of SBA-15, was beneficial for improving the selectivity to linear aldehyde. In situ high pressure FT-IR analysis suggested HRh(CO)2(PPh3)2 and HRh(CO)(PPh3)3 to be active species over the SBA-15/AEAPMDMS/Rh catalyst with TPP.

  4. Hydroformylation of Cyclohexene with Carbon Dioxide and Hydrogen Using Ruthenium Carbonyl Catalyst: Influence of Pressures of Gaseous Components

    PubMed Central

    Fujita, Shin-ichiro; Okamura, Shuhei; Akiyama, Yoshinari; Arai, Masahiko

    2007-01-01

    Hydroformylation of cyclohexene was studied with a catalyst system of Ru3(CO)12 and LiCl using H2 and CO2 instead of CO in NMP. The influence of H2 and CO2 pressures on the total conversion and the product distribution was examined. It was shown that increasing total pressure of H2 and CO2 promoted the reverse water gas shift reaction and increased the yield of cyclohexanecarboxaldehyde. Its hydrogenation to cyclohexanemethanol was promoted with increasing H2 pressure but suppressed with increasing CO2 pressure. Cyclohexane was also formed along with those products and this direct hydrogenation was suppressed with increasing CO2 pressure. The roles of CO2 as a promoter as well as a reactant were further examined by phase behavior observations and high pressure FTIR measurements.

  5. Diphosphines with natural bite angles near 120{degrees} increase selectivity for n-aldehyde formation in rhodium-catalyzed hydroformylation

    SciTech Connect

    Casey, C.P.; Whiteker, G.T.; Melville, M.G.

    1992-07-01

    The use of 2,2{prime}-bis[(diphenylphosphino)methyl]1,1{prime}-biphenyl (BISBI, 1), trans-1,2-bis[(diphenylphosphino)-methyl]cyclopropane (T-BDCP, 2), and other diphosphines with large natural bite angles as ligands in rhodium-catalyzed hydroformylation has been studied. The X-ray crystal structure of (BISBI)Rh(PPh{sub 3})(CO)H{center_dot}CH{sub 2}Cl{sub 2} (7{center_dot}CH{sub 2}Cl{sub 2}) indicated a trigonal bipyramidal structure with three phosphorus atoms in the equatorial plane. The P-Rh-P bite angle of the BISBI ligand in 7{center_dot}CH{sub 2}Cl{sub 2} of 124.8{degrees} is much smaller than the 152{degrees}P-Fe-P bite angle found in (BISBI)Fe(CO){sub 3} and indicates that the BISBI ligand is rather flexible. NMR studies indicate that rapid exchange ({Delta}G = 15.5 kcal mol{sup -1}) occurs between the coordinated PPh{sub 3} of 7 and free PPh{sub 3}. 7 reacted with CO to produce (BISBI)Rh(CO){sub 2}H(9), which was shown by IR and NMR studies to have a trigonal bipyramidal structure with BISBI in the equatorial plane and hydride in an apical position. The solution structures of the T-BDCP complexes (T-BDCP)Rh(PPh{sub 3})(CO)H(13) and (T-BDCP)Rh(CO){sub 2}H(14) were shown by spectroscopy to be similar to the related BISBI compounds. A correlation between the size of the natural bite angle of chelating diphosphines and the regioselectivity for formation of straight-chain aldehydes in the rhodium-catalyzed hydroformylation of 1-hexane was observed. 30 refs., 9 figs., 2 tabs.

  6. Beyond classical reactivity patterns: hydroformylation of vinyl and allyl arenes to valuable ?- and ?-aldehyde intermediates using supramolecular catalysis.

    PubMed

    Dydio, Pawe?; Detz, Remko J; de Bruin, Bas; Reek, Joost N H

    2014-06-11

    In this study, we report on properties of a series of rhodium complexes of bisphosphine and bisphosphite L1-L7 ligands, which are equipped with an integral anion binding site (the DIM pocket), and their application in the regioselective hydroformylation of vinyl and allyl arenes bearing an anionic group. In principle, the binding site of the ligand is used to preorganize a substrate molecule through noncovalent interactions with its anionic group to promote otherwise unfavorable reaction pathways. We demonstrate that this strategy allows for unprecedented reversal of selectivity to form otherwise disfavored ?-aldehyde products in the hydroformylation of vinyl 2- and 3-carboxyarenes, with chemo- and regioselectivity up to 100%. The catalyst has a wide substrate scope, including the most challenging substrates with internal double bonds. Coordination studies of the catalysts under catalytically relevant conditions reveal the formation of the hydridobiscarbonyl rhodium complexes [Rh(Ln)(CO)2H]. The titration studies confirm that the rhodium complexes can bind anionic species in the DIM binding site of the ligand. Furthermore, kinetic studies and in situ spectroscopic investigations for the most active catalyst give insight into the operational mode of the system, and reveal that the catalytically active species are involved in complex equilibria with unusual dormant (reversibly inactivated) species. In principle, this involves the competitive inhibition of the recognition center by product binding, as well as the inhibition of the metal center via reversible coordination of either a substrate or a product molecule. Despite the inhibition effects, the substrate preorganization gives rise to very high activities and efficiencies (TON > 18,000 and TOF > 6000 mol mol(-1) h(-1)), which are adequate for commercial applications. PMID:24841256

  7. Tandem isomerization/hydroformylation/hydrogenation of internal alkenes to n-alcohols using Rh/Ru dual- or ternary-catalyst systems.

    PubMed

    Yuki, Yamato; Takahashi, Kohei; Tanaka, Yoshiyuki; Nozaki, Kyoko

    2013-11-20

    A one-pot three-step reaction, isomerization/hydroformylation/hydrogenation of internal alkenes to n-alcohols, was accomplished by employing a Rh/Ru dual-catalyst system. By using a combination of Rh(acac)(CO)2/bisphosphite and Shvo's catalyst, (Z)-2-tridecene was converted to 1-tetradecanol in 83% yield with high normal/iso selectivity (n/i = 12). The method was applicable to other internal alkenes, including functionalized alkenes, such as an alkenol and an alkenoate. Furthermore, addition of a third component, Ru3(CO)12, effectively improved the n/i ratio in the tandem isomerization/hydroformylation/hydrogenation of methyl oleate (from n/i = 1.9 to 4.4). Control experiments revealed that the isomerization was mediated by both Rh and Ru and that the coexistence of Rh and Ru was essential for hydrogenation of aldehyde under H2/CO. PMID:24191719

  8. New chiral phosphinephosphinite ligands: Application to stereoselective synthesis of a key intermediate of 1{beta}-methyl carbapenems by Rh(I)-catalyzed asymmetric hydroformylation

    SciTech Connect

    Saito, Takao; Yoshida, Akifumi; Matsumura, Kazuhiko

    1995-12-31

    Transition metal catalyzed asymmetric hydroformylation is an attractive and highly useful homologation process for organic synthesis. Recently, the authors reported that the Rh(I) complexes of phosphinephosphite BINAPHOS are highly efficient catalysts for enantioselective hydroformylation of a variety of olefins. This time, the authors have designed and synthesized new chiral phosphinephosphinite ligands having binaphthyl backbone, (R)-2-diarylphosphino-2{prime}-diarylphosphinoxy-1,1{prime}-binaphthy1 (hereafter abbreviated (R)-BIPNITE). The Rh(I) complexes of these ligands are effective catalysts for the asymmetric hydroformylation of 4-vinylazetidin-2-one to give the corresponding oxo-aldehyde 3{beta} as the major product in very high diastereoselectivities and in good regioselectivities. Interestingly, modifications of the aryl substituents in phosphine and phosphinite moieties afforded higher selectivities. Aldehyde 3{beta} was easily oxidized with NaClO{sub 2} to 4, a key intermediate of 1{beta}-methyl carbapenems. Thus, the present method provides a new practical route to a versatile key intermediate for the synthesis of carbapenem antibiotics.

  9. Catalytic properties of RhCl[sub 3] [center dot] 3H[sub 2]O immobilized on the modified poly(styrene-divinylbenzene) copolymer in aqueous phase hydroformylation of propylene

    SciTech Connect

    Ro, K.S.; Woo, S.I. )

    1994-02-01

    RhCl[sub 3] [center dot] 3H[sub 2]O and RhCl(CO)(PPh[sub 3])[sub 2] were immobilized on the poly(styrene-divinylbenzene) copolymer (PS/DVB) containing -CH[sub 2]P(C[sub 6]H[sub 4]SO[sub 3]H)[sub 2] (DPPDS: diphenylphosphine disulfonate) groups to give active and stable hydroformylation catalysts in an aqueous phase. Solid-state [sup 31]P NMR spectra and FTIR analysis indicate that the structure of RhCl[sub 3] [center dot] 3H[sub 2]O immobilized on the PS/DVB containing DPPDS groups (Rh(III)/SPPS) is similar to that of RhCl(CO)(PPh[sub 3])[sub 2] immobilized on the same polymer (Rh(I)/SPPS). The hydroformylation of propylene using these catalysts (Rh(III)/SPPS) has been investigated at 373 K and in the pressure range between 5 and 40 atm in an aqueous phase. The rate of hydroformylation was approximately first order with respect to catalyst concentration and increased with the increase of propylene concentration up to 0.45 mol/liter. The rate also increased with the increase of hydrogen pressure. However, the rate of hydroformylation passed through a maximum with the increase of partial pressure of carbon monoxide. The activation energy of propylene hydroformylation catalyzed over Rh(III)/SPPS between 353 and 393 K was found to be 12.1 kcal/mol. Kinetic study with Rh(III)/SPPS containing various amounts of SO[sub 3]H group indicates that SO[sub 3]H groups play an important role in improving the catalytic activity in the aqueous phase hydroformylation. 18 refs., 11 figs., 2 tabs.

  10. Rh{sub 4} carbonyl clusters coordinated with tris(hydroxymethyl)phosphine grafted onto SiO{sub 2} surfaces and structural control of active sites in gas-phase olefin hydroformylation reactions

    SciTech Connect

    Shido, Takafumi; Okazaki, Takumi; Ichikawa, Masaru

    1995-12-01

    The structure of attached Rh{sub 4}(CO){sub 12} on tris(hydroxymethyl)-phosphine (P(CH{sub 2}OH){sub 3},THP)-modified silica was investigated by EXAFS and IR spectroscopy. The catalytic behavior of the Rh{sub 4} carbonyl cluster coordinated with THP ligands anchored on SiO{sub 2}(P(CH{sub 2}OH){sub 3-x}(CH{sub 2}OSi){sub x}(x = 1, 2)) in gas-phase hydroformylation reactions was investigated. The number of THP ligands coordinating to the Rh{sub 4} cluster depended on the loading of THP. Rh{sub 4} clusters on SiO{sub 2} loaded with 6.2 wt% THP, on which the average distance of P atoms of the neighboring THP was 8 {angstrom}, were coordinated by two THP ligands, and the Rh{sub 4} clusters were distorted. Rh{sub 4} clusters on SiO{sub 2} loaded with 1.6 wt% THP, on the other hand, were coordinated by one THP ligand and the clusters were not distorted. The attached cluster was active for olefin hydroformylation reaction. The reaction rate of hydroformylation on this catalyst was comparable to that on Wilkinson catalyst in solution. The distorted Rh{sub 4} framework, which is coordinated by two THP, was much more active in hydroformylation reactions than was that of monosubstituted clusters of THP/SiO{sub 2} or Rh{sub 4}(CO){sub 10}(THP){sub 2} in solution. In situ IR spectroscopy and EXAFS revealed that a reversible coordination of CO ligands attached to the Rh{sub 4} cluster was associated with the selective hydroformylation reaction. In the hydroformylation atmosphere, the Rh{sub 4} cluster is almost saturated by CO ligands and effectively suppressed the hydrogenation reaction as a side reaction of hydroformylation. In contrast, under the reaction condition of hydrogenation, CO ligands were removed to increase the reaction rate of hydrogenation. The reversible CO bonding in the surface-grafted Rh{sub 4} site was related to the dynamic control of selective hydroformylation of olefins. 43 refs., 12 figs., 5 tabs.

  11. Recoverable and recyclable water-soluble sulphonated salicylaldimine Rh(I) complexes for 1-octene hydroformylation in aqueous biphasic media.

    PubMed

    Matsinha, Leah C; Mapolie, Selwyn F; Smith, Gregory S

    2015-01-21

    A series of water-soluble Rh(i) mononuclear complexes of general formula: [Rh(sulphsal-X-R)(COD)] [sulphsal = sulphonated salicylaldimine, COD = cyclooctadiene; where R = H, Cl, CH3 and X = H, (t)Bu] have been synthesized. All the compounds were characterised using various spectroscopic and analytical techniques such as nuclear magnetic resonance spectroscopy, infrared spectroscopy, single crystal X-ray diffraction (for complex ) and mass spectrometry. All the compounds display excellent water-solubility at room temperature and were tested as catalyst precursors in the aqueous biphasic hydroformylation of 1-octene. The catalysts could be easily recovered by phase separation and were used up to 5 times without any significant loss in activity and 1-octene conversion. Very high yields of the expected aldehydes were obtained without addition of any phase transfer agents, co-solvents or hydrophobic ligands. Excellent aldehyde chemoselectivity is observed for all the catalysts but this varied each time the catalysts were recycled, with the formation of a small amount of internal olefins. ICP-OES and mercury poisoning experiments show that a combination of homogeneous catalysis and catalysis mediated by nanoparticles is taking place in these systems. PMID:25415263

  12. Heterogenised N-heterocyclic carbene complexes: synthesis, characterisation and application for hydroformylation and C-C bond formation reactions.

    PubMed

    Dastgir, Sarim; Coleman, Karl S; Green, Malcolm L H

    2011-01-21

    The imidazolium salts: 1-mesityl-3-(3-trimethoxysilylpropyl)imidazolium iodide and 1-tert-butyl-3-(3-trimethoxysilylpropyl)imidazolium iodide, abbreviated as (tmpMes)HI (3a) and (tmp(t)Bu)HI (3b), respectively, have been synthesised. The palladium(ii) complexes (?(3)-C(3)H(5)) (tmpMes)PdCl (5a) and (?(3)-C(3)H(5))(tmp(t)Bu)PdCl (5b), rhodium(i) and iridium(i) complexes (?(4)-1,5-COD) (tmpMes)MCl, M = Rh (6a), Ir (7a) and (?(4)-1,5-COD)(tmp(t)Bu)MCl, where M = Rh (6b), Ir (7b), were synthesised by silver transmetallation reactions using the silver(i) complexes (tmpMes)AgI (4a) and (tmp(t)Bu)AgI (4b). The iridium complex 7b has been structurally characterised. The Pd(ii) and Rh(i) complexes have been immobilised by attachment to chemically modified MCM-41. The immobilised palladium(ii) materials have been tested as recyclable catalysts for Suzuki type C-C bond formation reactions in water and the immobilised rhodium(i) materials have been examined for their catalytic ability for the hydroformylation of 1-octene. PMID:21116572

  13. Stereoelectronic effects in a homologous series of bidentate cyclic phosphines. A clear correlation of hydroformylation catalyst activity with ring size.

    PubMed

    Haddow, Mairi F; Middleton, Ann J; Orpen, A Guy; Pringle, Paul G; Papp, Rainer

    2009-01-01

    The homologous series of diphosphines (CH(2))(n-1)P(CH(2))(3)P(CH(2))(n-1) where n = 5 (L(5)), 6 (L(6)), or 7 (L(7)) have been synthesized from the corresponding PhP(CH(2))(n-1). Treatment of [PtCl(2)(cod)] with L(5-7) gave the 6-membered chelates cis-[PtCl(2)(L(5-7))], the crystal structures for which reveal that L(5-7) have very similar steric bulk and bite angles. Treatment of [Rh(2)Cl(2)(CO)(4)] with L(5-7) gave the binuclear trans-[Rh(2)Cl(2)(CO)(2)(micro-L(5-7))(2)] with syn and anti orientations of the CO and Cl ligands suggested by the (31)P NMR spectra and the crystal structures of syn-trans-[Rh(2)Cl(2)(CO)(2)(micro-L(5))(2)] and anti-trans-[Rh(2)Cl(2)(CO)(2)(micro-L(7))(2)]. The nu(CO) values for trans-[Rh(2)Cl(2)(CO)(2)(micro-L(5-7))(2)] indicate that the donor strength increases in the order L(5) < L(6) < L(7). A study of rhodium-catalysed hydroformylation of 1-octene using diphosphines L(5-7) is described. The catalyst activity decreases with increasing phosphacycle ring size: L(5) > L(6) > L(7). PMID:19081990

  14. An operando FTIR spectroscopic and kinetic study of carbon monoxide pressure influence on rhodium-catalyzed olefin hydroformylation.

    PubMed

    Kubis, Christoph; Sawall, Mathias; Block, Axel; Neymeyr, Klaus; Ludwig, Ralf; Börner, Armin; Selent, Detlef

    2014-09-01

    The influence of carbon monoxide concentration on the kinetics of the hydroformylation of 3,3-dimethyl-1-butene with a phosphite-modified rhodium catalyst has been studied for the pressure range p(CO)=0.20-3.83?MPa. Highly resolved time-dependent concentration profiles of the organometallic intermediates were derived from IR spectroscopic data collected in situ for the entire olefin-conversion range. The dynamics of the catalyst and organic components are described by enzyme-type kinetics with competitive and uncompetitive inhibition reactions involving carbon monoxide taken into account. Saturation of the alkyl-rhodium intermediates with carbon monoxide as a cosubstrate occurs between 1.5 and 2?MPa of carbon monoxide pressure, which brings about a convergence of aldehyde regioselectivity. Hydrogenolysis of the acyl intermediate is fast at 30?°C and low pressure of p(CO)=0.2?MPa, but is of minus first order with respect to the solution concentration of carbon monoxide. Resting 18-electron hydrido and acyl complexes that correspond to early and late rate-determining states, respectively, coexist as long as the conversion of the substrate is not complete. PMID:25081298

  15. Rhodium-catalyzed hydroformylation of ketal-masked ?-isophorone: computational explanation for the unexpected reaction evolution of the tertiary Rh-alkyl via an exocyclic ?-elimination derivative.

    PubMed

    Alagona, Giuliano; Ghio, Caterina

    2015-05-28

    Ketal-masked ?-isophorone (7,9,9-trimethyl-1,4-dioxaspiro[4.5]dec-7-ene) is an interesting case study of Rh-catalyzed hydroformylations not only for the competition between secondary and tertiary rhodium alkyls but also for the unexpected isomerization of the tertiary Rh-alkyl to the exocyclic olefin which undergoes hydroformylation, yielding the acetaldehyde derivative (2) of 7,9,9-trimethyl-1,4-dioxaspiro[4.5]decane. Although experimental results at 100 °C pointed to reaction reversibility, the reason for this kind of behavior was however obscure. A thorough density functional theory (DFT) computational investigation of the various transition states (TS) and intermediates along the reaction pathways making use of B3P86 hybrid functionals and the 6-31G* basis set, coupled to effective core potentials for Rh in the LanL2DZ valence basis set, has been carried out to shed some light on the reaction mechanism. The TS barrier heights, based on alkyl-Rh TS free energies, computed under the hypothesis of nonreversibility were in favor of a normal hydroformylation reaction (III:II = 70:30). While the endocyclic olefins produced skew or twisted arrangements of the six-membered ring similarly to the CO insertion TS that can be even higher than the alkyl-Rh ones, grid-point calculations during the potential energy surface (PES) scan produced the much more stable chair conformation for the exocyclic olefin complex. The relevant TS were found to be very favorable as well, thus explaining the preference for the exocyclic arrangement of the tertiary intermediate, for which the reaction is therefore entirely reversible and invariably proceeds to the acetaldehyde derivative (2). Conversely for the secondary isomers, the reaction is only partially reversible, thus enriching the tertiary fraction and producing the secondary aldehyde (3) in a very limited amount. PMID:25416149

  16. Catalytic performance and mechanism for oxygenated compound formation for ethylene hydroformylation over supported Ru-M bimetallic carbonyl cluster-derived catalysts

    SciTech Connect

    Feng-Shou Xiao ); Ichikawa, Masaru )

    1994-06-01

    The catalytic performance in ethylene hydroformylation over SiO[sub 2], MgO, and carbon-supported Ru, Ru-Co, Ru-Mn, Ru-Cr, and Co carbonyl cluster-derived catalysts has been investigated, and it was found that the catalysts derived from Ru monometallic and Ru-Co bimetallic carbonyl clusters are active in ethylene hydroformylation. The presence of Co atoms in Ru-Co carbonyl clusters led to a remarkable increase in the rate of product formation, especially for oxygenates. The Ru-Mn bimetallic carbonyl cluster-derived catalyst showed similar conversion, but it exhibited poor activity and selectivity for oxygenates as compared with catalysts derived from Ru[sub 6]C(CO)[sub 17]. In contrast to the Ru[sub 6]C(CO)[sub 17] carbonyl cluster-derived catalyst, the Ru-Cr bimetallic carbonyl cluster-derived catalyst exhibited very low activity and selectivity for ethane and oxygenates, indicating that the Cr sites in Ru-Cr bimetallic carbonyl cluster-derived catalyst have a poisoning effect on ethylene hydroformylation. The nature of support has been shown to have a large influence on the catalytic activity and selectivity of the resulting catalyst. The effect of Co promotion in Ru-Co carbonyl clusters on silica and carbon was much stronger than that on MgO. The nature of these Ru-Co/SiO[sub 2] catalysts has been investigated by infrared and X-ray photoelectron spectroscopes. 70 refs., 14 figs., 6 tabs.

  17. Electronically dissymetric DIPHOS derivatives give higher n:i regioselectivity in rhodium-catalyzed hydroformylation than either of their symmetric counterparts

    SciTech Connect

    Casey, C.P.; Paulsen, E.L.; Beuttenmueller, E.W.; Proft, B.R.; Matter, B.A.; Powell, D.R.

    1999-01-13

    Electronic effects on rhodium-catalyzed hydroformylation of 1-hexene with electronically dissymmetric DIPHOS derivatives [3,5-(CF{sub 3}){sub 2}C{sub 6}H{sub 3}]{sub 2}PCH{sub 2}CH{sub 2}PPH{sub 2} = [DIPHOS-(3,5-CF{sub 3},H)] (1), [2-(CF{sub 3})C{sub 6}H{sub 4}]{sub 2}PCH{sub 2}CH{sub 2}PPh{sub 2} = [DIPHOS-(2-CF{sub 3}H)] (2), [3,5-(CF{sub 3}){sub 2}C{sub 6}H{sub 3}]{sub 2}PCH{sub 2}CH{sub 2}P[2-(CH{sub 3})C{sub 6}H{sub 4}]{sub 2} = [DIPHOS-(3,5-CF{sub 3}2-CH{sub 3})] (3), and [2-(CF{sub 3})C{sub 6}H{sub 4}]{sub 2}PCH{sub 2}CH{sub 2}P[2-(CH{sub 3})C{sub 6}H{sub 4}]{sub 2} = [DIPHOS-(2-CF{sub 3},2-CH{sub 3})] (4) were investigated. Two apical-equatorial chelate isomers were observed for model (diphosphine)Ir(CO){sub 2}H complexes of dissymmetric diphosphines 1--4. In each case, the equatorial phosphine of the major isomer (96--60%) had electron-withdrawing aryl substituents. These dissymmetric DIPHOS derivatives were used to test the hypothesis that an electron-withdrawing substituent on an equatorial phosphine increases the hydroformylation n:i ratio while an electron-withdrawing substituent on an apical phosphine decreases the n:i ratio. In agreement with the predictions of this hypothesis, hydroformylation with the dissymmetric diphosphine ligand DIPHOS-(3,5-CF{sub 3},H) (1), gave an n:i ratio of 4.2:1, higher than either of the symmetric ligands DIPHOS, 2.6:1, and DIPHOS-(3,5-CF{sub 3}), 1.3:1. Similar observations were made for hydroformylations with 2--4.

  18. Asymmetric hydroformylation-initiated tandem sequences for syntheses of (+)-patulolide C, (-)-pyrenophorol, (+)-decarestrictine L, and (+)-prelog djerassi lactone.

    PubMed

    Risi, Roberto M; Maza, Andrew M; Burke, Steven D

    2015-01-01

    Four different Rh-catalyzed asymmetric hydroformylation (AHF) tandem reactions have been developed in the context of the total syntheses of (+)-patulolide C, (-)-pyrenophorol, (+)-decarestrictine L, and (+)-Prelog-Djerassi lactone. A total synthesis of (+)-patulolide C has been accomplished in three steps utilizing a Rh(I)-catalyzed Z-selective anti-Markovnikov hydroacetoxylation of a known alkyne to give a Z-enol acetate with excellent selectivity. An AHF/intramolecular Wittig olefination cascade was utilized to set the C4-hydroxyl stereochemistry, E-olefin geometry, and form the macrolactone. In addition, both (-)-pyrenophorol and (+)-decarestrictine L have been synthesized from the enantiomeric (4R)- and (4S)-4-(tert-butyldimethylsiloxy)-1-pentyne in five and four steps, respectively. These syntheses feature Ru(II)-catalyzed Z-selective anti-Markovnikov hydroacetoxylation of terminal alkynes followed by AHF/Wittig olefination sequences to rapidly establish functionality and stereogenicity. A synthesis of (+)-Prelog-Djerassi lactone was accomplished in three isolations from the known 1-vinyl-4-methyl-2,6,7-trioxabicyclo[2.2.2]octane ortho ester. An AHF/crotylation tandem sequence has been developed to set the C2-C4 stereochemistry. An asymmetric hydrogenation was employed to set the C6 stereochemistry, resulting in an especially efficient enantioselective synthesis from achiral starting material. In summary, these syntheses have greatly improved efficiency in terms of atom-economy, catalytic stereoselective transformations, inexpensive reagents, step-counts, and overall yield when compared with previous synthetic attempts. PMID:25398097

  19. Des Moines.

    ERIC Educational Resources Information Center

    Gore, Deborah, Ed.

    1988-01-01

    This document, intended for elementary students, contains articles and activities designed to acquaint young people with the history of Des Moines, Iowa. The articles are short, and new or difficult words are highlighted and defined for young readers. "The Raccoon River Indian Agency" discusses the archeological exploration of the indian…

  20. Realistic energy surfaces for real-world systems: an IMOMO CCSD(T):DFT scheme for rhodium-catalyzed hydroformylation with the 6-DPPon ligand.

    PubMed

    Gellrich, Urs; Himmel, Daniel; Meuwly, Markus; Breit, Bernhard

    2013-11-25

    The hydroformylation of terminal alkenes is one of the most important homogeneously catalyzed processes in industry, and the atomistic understanding of this reaction has attracted enormous interest in the past. Herein, the whole catalytic cycle for rhodium-catalyzed hydroformylation with the 6-diphenylphosphinopyridine-(2H)-1-one (6-DPPon) ligand 1 was studied. This catalytic transformation is challenging to describe computationally, since two requirements must be met: 1) changes in the hydrogen-bond network must be modeled accurately and 2) bond-formation/bond-breaking processes in the coordination sphere of the rhodium center must be calculated accurately. Depending on the functionals used (BP86, B3LYP), the results were found to differ strongly. Therefore, the complete cycle was calculated by using highly accurate CCSD(T) computations for a PH3 model ligand. By applying an integrated molecular orbital plus molecular orbital (IMOMO) method consisting of CCSD(T) as high level and DFT as low-level method, excellent agreement between the two functionals was achieved. To further test the reliability of the calculations, the energetic-span model was used to compare experimentally derived and computed activation barriers. The accuracy of the new IMOMO method apparently makes it possible to predict the catalytic potential of real-world systems. PMID:24127405

  1. Triphenylphosphane-functionalised amphiphilic copolymers: tailor-made support materials for the efficient and selective aqueous two-phase hydroformylation of 1-octene.

    PubMed

    Bortenschlager, Martin; Schöllhorn, Nicole; Wittmann, Anton; Weberskirch, Ralf

    2007-01-01

    Amphiphilic copolymers (random P1 and block P2) based on 2-oxazolines were synthesised with triphenylphosphane ligands covalently linked to the polymers by means of a metal-free synthesis route. The resulting macroligands were used in the aqueous two-phase hydroformylation of 1-octene. The influence of the polymer architecture (random and block copolymers) on activity and selectivity of the hydroformylation reaction was investigated and compared with that of nonfunctionalised copolymers (random P3 and block P4) and Rh(I)/triphenylphosphane trisulfonate as a water-soluble catalyst. The highest activities were observed for the random copolymer P1 (p=50 bar, T=100 degrees C, c=8 x 10(-4) mol L(-1)) with a turnover frequency (TOF) of 3700 h(-1), whereas the corresponding block copolymer P2 reached TOF numbers of 1630 h(-1). Additionally, both macroligands indicated efficient suppression of isomerisation and led to almost constant n/iso selectivities of about 3 after complete substrate conversion. Copolymers P3 and P4 showed, under identical reaction conditions, strong isomerisation after 40-60 % conversion (n/iso approximately 0.7) and maximum activities of 1560 h(-1) (P3) and 1330 h(-1) (P4) at a concentration of 5 x 10(-3) mol L(-1). PMID:17042041

  2. Interception and Characterization of Catalyst Species in Rhodium Bis(diazaphospholane)-Catalyzed Hydroformylation of Octene, Vinyl Acetate, Allyl Cyanide, and 1-Phenyl-1,3-butadiene.

    PubMed

    Nelsen, Eleanor R; Brezny, Anna C; Landis, Clark R

    2015-11-11

    In the absence of H2, reaction of [Rh(H) (CO)2(BDP)] [BDP = bis(diazaphospholane)] with hydroformylation substrates vinyl acetate, allyl cyanide, 1-octene, and trans-1-phenyl-1,3-butadiene at low temperatures and pressures with passive mixing enables detailed NMR spectroscopic characterization of rhodium acyl and, in some cases, alkyl complexes of these substrates. For trans-1-phenyl-1,3-butadiene, the stable alkyl complex is an ?(3)-allyl complex. Five-coordinate acyl dicarbonyl complexes appear to be thermodynamically preferred over the four-coordinate acyl monocarbonyls at low temperatures and one atmosphere of CO. Under noncatalytic (i.e., no H2 present) reaction conditions, NMR spectroscopy reveals the kinetic and thermodynamic selectivity of linear and branched acyl dicarbonyl formation. Over the range of substrates investigated, the kinetic regioselectivity observed at low temperatures under noncatalytic conditions roughly predicts the regioselectivity observed for catalytic transformations at higher temperatures and pressures. Thus, kinetic distributions of off-cycle acyl dicarbonyls constitute reasonable models for catalytic selectivity. The Wisconsin high-pressure NMR reactor (WiHP-NMRR) enables single-turnover experiments with active mixing; such experiments constitute a powerful strategy for elucidating the inherent selectivity of acyl formation and acyl hydrogenolysis in hydroformylation reactions. PMID:26466510

  3. Caractérisation de l'augmentation des transferts thermiques dans une couche de liquide diélectrique soumise à une injection unipolaire de charges électriques

    NASA Astrophysics Data System (ADS)

    Traoré, Philippe; Koulova-Nenova, D.; Romat, H.; Perez, A.

    2009-03-01

    The electro-thermo-convective flow in a horizontal dielectric liquid layer placed between two electrodes and subjected to an injection of electric charges from one of the electrodes and at the same time to a thermal gradient is studied numerically. We consider the case of a strong charge injection in order to only take into account the Coulomb force disregarding the dielectric forces, from above and below the layer. The effect of the action of both electric and thermal fields on the dielectric liquid layer is analyzed and the behavior of the flow when these fields compete or cooperate is studied. It is demonstrated that the electrically induced convection enhances the heat transfer. To cite this article: Ph. Traoré et al., C. R. Mecanique 337 (2009).

  4. Page 1 sur 5 Direction des Affaires Financires

    E-print Network

    Sart, Remi

    Chromatographie Liquide Haute Performance (HPLC) ICCF Lot n° 1 : HPLC avec application de l'analyse des acides aminés intégrée Lot n° 2 : HPLC avec bascule technique phase inverse / phase normale rapide Acquisition

  5. Service des immeubles Service des Immeubles

    E-print Network

    Laval, Université

    les gaz ayant un effet de serre, trois des six gaz pris en compte par le protocole de Kyoto, soit le travail employés dans la réalisation du bilan des GES est basé sur les références suivantes : GHG Protocol

  6. Effect of composition of the aqueous phase on catalytic properties of RhCl{sub 3} modified with a polycation in hydroformylation of 1-hexene

    SciTech Connect

    Kolesnichenko, N.V.; Sharikova, M.V.; Murzabekova, T.K.

    1995-10-01

    Water-soluble catalytic systems based on RhCl{sub 3} and the salts of polycations (poly-N,N- diallyl-N,N-dimethylammonium chloride and poly-NN-dialtyl-N-methylaminodihydrophosphate) have been studied. It has been established that the rate of hydroformylation of 1-hexene increases with increasing pH of the aqueous phase. The replacement of the alkyl group at the nitrogen atom with the hydrogen atom in a polycation makes it possible to form a stable catalytic system at pH > 5. The addition of low molecular electrolytes (NaCl, Na{sub 2}SO{sub 4}, and NaPO{sub 4}) also affects the catalytic properties of the studied catalytic systems. Stability of a catalytic system is enhanced with increasing charge of an anion of a low molecular electrolyte, which is, apparently, due to formation of intra- and intermolecular bonds in polyelectrolytes.

  7. Controlled deposition from the gas phase of surface species on amorphous supports: Preparation of ruthenium-bipyridine catalysts for 1-hexane hydroformylation and water-gas shift reaction

    SciTech Connect

    Hirva, P.; Venaelaeinen, T.; Pakkanen, T.A. )

    1994-08-01

    Controlled stepwise surface reactions were studied to prepare supported ruthenium-bipyridine catalysts. Ru[sub 3](CO)[sub 12] and 2,2[prime]-bipyridine were introduced onto the support from the gas phase in a fluidized bed reactor. With this method the introduction of the precursors can be carried out independently by successive pulses. The possibilities to control metal content, properties of the surface species, and dispersion were studied by varying the deposition conditions, e.g., temperature and carrier gas. The catalysts were tested in 1-hexane hydroformylation and the water-gas shift reaction. Deposition of the precursors from the gas phase was found to produce active catalysts for both reactions. In this water-gas shift reaction the highest activities were 2-2.5 times greater than those obtained with catalysts prepared by impregnation. 35 refs., 4 figs., 4 tabs.

  8. Hydroformylation of olefins and reductive carbonylation of aryl halides with syngas formed ex situ from dehydrogenative decarbonylation of hexane-1,6-diol.

    PubMed

    Christensen, Stig Holden; Olsen, Esben P K; Rosenbaum, Jascha; Madsen, Robert

    2015-01-21

    A variety of primary alcohols have been investigated as convenient substrates for the ex situ delivery of carbon monoxide and molecular hydrogen in a two-chamber reactor. The gaseous mixture is liberated in one chamber by an iridium-catalysed dehydrogenative decarbonylation of the alcohol and then consumed in the other chamber in either a rhodium-catalysed hydroformylation of olefins or a palladium-catalysed reductive carbonylation of aryl halides. Hexane-1,6-diol was found to be the optimum alcohol for both reactions where moderate to excellent yields were obtained of the product aldehydes. A relatively low pressure of 1.5-2.4 bar was measured in the closed system during the two transformations. PMID:25410149

  9. Profil epidemiologique des brulures d'enfants admis au Centre National des Brules, Maroc

    PubMed Central

    Zahid, A.; Atannaz, J.; Alaoui, M.; Rafik, A.; Ezzoubi, M.; Diouri, M.; Chlihi, A.; Bahechar, N.; Boukind, E.H.

    2011-01-01

    Summary Ce travail rétrospectif analyse les particularités épidémiologiques de 543 cas de brûlures d'enfants, représentant 45,7% des admissions de notre centre, en vue de déterminer les éléments pouvant contribuer à renforcer la prévention, qui reste le traitement de choix de cette pathologie. La moyenne d'âge est de 4,25 ans avec une prédilection pour la tranche d'âge d'un à cinq ans, avec 42,5% des cas. Une atteinte masculine est retrouvée dans 63,5% des cas. La brûlure survient à domicile dans 85,1% et accidentellement dans 95% des cas. Les brûlures thermiques représentent 96,5% des causes dominées par les liquides dans 69,3% des cas. La surface cutanée brûlée est ? 20% dans 52,3%. La brûlure intéresse essentiellement les membres supérieurs (79,1%). 56,8% des enfants sont transférés par d'autres hôpitaux et le délai de prise en charge hospitalière est supérieur à 6 heures dans 65,5%. Le taux de mortalité a été de 13,2%. PMID:22639559

  10. Diethylstilbestrol (DES) and Cancer

    MedlinePLUS

    ... products that contained DES. DES Product Names Nonsteroidal Estrogens Benzestrol Chlorotrianisene Comestrol Cyren A. Cyren B. Delvinal ... Stils Synestrin Synestrol Synthosestrin Tace Vallestril Willestrol Nonsteroidal Estrogen-Androgen Combinations Amperone Di-Erone Estan Metystil Teserene ...

  11. DES RESSOURCES RENOUVELABLES

    E-print Network

    Laval, Université

    DES SCIENCES DE L'AGRICULTURE ET DE L'ALIMENTATION Vice-décanat à la recherche Pavillon Paul LA FSAA La Faculté des sciences de l'agriculture et de l'alimentation (FSAA) permet d'accéder à l plantes, contribuent à la réduction du diabète et des maladies cardiovasculaires par l'alimentation

  12. Direction des Relations Internationales

    E-print Network

    Debarre, Olivier

    Direction des Relations Internationales ERASMUS : liste des accords par pays Les candidatures Philosophie des Sciences 15/06 15/12 COLOGNE Universität zu Köln Littérature et linguistique 15/06 15/12 WÜRZBOURG Université J. Maximilians Littérature et Linguistique 15/06 15/01 AUTRICHE VIENNE Université de

  13. Hydroformylation of 1-octene using low-generation Rh(I) metallodendritic catalysts based on a tris-2-(2-pyridyliminoethyl)amine scaffold.

    PubMed

    Makhubela, Banothile C E; Jardine, Anwar M; Westman, Gunnar; Smith, Gregory S

    2012-09-21

    The synthesis and characterization of low-generation pyridylimine Rh(I) metallodendrimers is described. These metallodendrimers were obtained via a Schiff base condensation of tris-2-(aminoethyl)amine with 2-pyridinecarboxaldehyde to afford the tris-2-(2-pyridylimine ethyl) amine ligand (1). Subsequent complexation reactions with [RhCl(CO)(2)](2) and [RhCl(COD)](2) yielded the corresponding metal-containing dendrimers containing -RhCl(CO) and -Rh(COD) moieties on the periphery. These new rhodium metallodendrimers (2 and 3) and their precursor ligand (1) are thermally stable and have been characterized using (1)H NMR, (13)C NMR, (31)P NMR, FT-IR spectroscopy, elemental analysis as well as mass spectrometry. The Rh(I) metallodendrimers are highly active and chemo- and regioselective in the hydroformylation of 1-octene. Aldehydes were favoured at moderate to high temperatures (95 °C and 75 °C) and pressure (30 bars), while more iso-octenes were formed at low temperature (55 °C) and pressures (5 and 10 bars). The mononuclear analogues (5 and 6) also produced more aldehydes (albeit showing catalyst decomposition at 95 °C and 75 °C, 30 bars) and these aldehydes were mostly branched. PMID:22847737

  14. Ring opening metathesis polymerization-derived block copolymers bearing chelating ligands: synthesis, metal immobilization and use in hydroformylation under micellar conditions.

    PubMed

    Pawar, Gajanan M; Weckesser, Jochen; Blechert, Siegfried; Buchmeiser, Michael R

    2010-01-01

    Norborn-5-ene-(N,N-dipyrid-2-yl)carbamide (M1) was copolymerized with exo,exo-[2-(3-ethoxycarbonyl-7-oxabicyclo[2.2.1]hept-5-en-2-carbonyloxy)ethyl]trimethylammonium iodide (M2) using the Schrock catalyst Mo(N-2,6-Me?-C?H?)(CHCMe?Ph)(OCMe(CF?)?)?[Mo] to yield poly(M1-b-M2). In water, poly(M1-b-M2) forms micelles with a critical micelle-forming concentration (cmc) of 2.8 x 10?? mol L?¹; Reaction of poly(M1-b-M2) with [Rh(COD)Cl]? (COD = cycloocta-1,5-diene) yields the Rh(I)-loaded block copolymer poly(M1-b-M2)-Rh containing 18 mg of Rh(I)/g of block copolymer with a cmc of 2.2 x 10?? mol L?¹. The Rh-loaded polymer was used for the hydroformylation of 1-octene under micellar conditions. The data obtained were compared to those obtained with a monomeric analogue, i.e. CH?CON(Py)?RhCl(COD) (C1, Py = 2-pyridyl). Using the polymer-supported catalyst under micellar conditions, a significant increase in selectivity, i.e. an increase in the n:iso ratio was accomplished, which could be further enhanced by the addition of excess ligand, e.g., triphenylphosphite. Special features of the micellar catalytic set up are discussed. PMID:20502652

  15. Profil des candidats : Master de Biologie ou Biologie des Systmes

    E-print Network

    Radulescu, Ovidiu

    Profil des candidats : Master de Biologie ou Biologie des Systèmes Candidatures en ligne : sur le approche de biologie des systèmes du contrôle de l'entrée et de la sortie mitotiques chez les eucaryotes

  16. Médecine des voyages

    PubMed Central

    Aw, Brian; Boraston, Suni; Botten, David; Cherniwchan, Darin; Fazal, Hyder; Kelton, Timothy; Libman, Michael; Saldanha, Colin; Scappatura, Philip; Stowe, Brian

    2014-01-01

    Résumé Objectif Définir la pratique de la médecine des voyages, présenter les éléments fondamentaux d’une consultation complète préalable aux voyages à des voyageurs internationaux et aider à identifier les patients qu’il vaudrait mieux envoyer en consultation auprès de professionnels de la médecine des voyages. Sources des données Les lignes directrices et les recommandations sur la médecine des voyages et les maladies liées aux voyages publiées par les autorités sanitaires nationales et internationales ont fait l’objet d’un examen. Une recension des ouvrages connexes dans MEDLINE et EMBASE a aussi été effectuée. Message principal La médecine des voyages est une spécialité très dynamique qui se concentre sur les soins préventifs avant un voyage. Une évaluation exhaustive du risque pour chaque voyageur est essentielle pour mesurer avec exactitude les risques particuliers au voyageur, à son itinéraire et à sa destination et pour offrir des conseils sur les interventions les plus appropriées en gestion du risque afin de promouvoir la santé et prévenir les problèmes médicaux indésirables durant le voyage. Des vaccins peuvent aussi être nécessaires et doivent être personnalisés en fonction des antécédents d’immunisation du voyageur, de son itinéraire et du temps qu’il reste avant son départ. Conclusion La santé et la sécurité d’un voyageur dépendent du degré d’expertise du médecin qui offre le counseling préalable à son voyage et les vaccins, au besoin. On recommande à ceux qui donnent des conseils aux voyageurs d’être conscients de l’ampleur de cette responsabilité et de demander si possible une consultation auprès de professionnels de la médecine des voyages pour tous les voyageurs à risque élevé.

  17. RPERTOIRE DES PROJETS DE LA

    E-print Network

    .................................................................................. 57 Département des sciences animales Élaboration, mise à l'essai et implantation de mesure de la qualité des services de soutien Contrat

  18. Portail des maths & PLM 2.0 Jacquelin Charbonnel -Journes des DU -Paris, 11 avril 2013 Portail des maths

    E-print Network

    Menichi, Luc

    Portail des maths & PLM 2.0 Jacquelin Charbonnel - Journées des DU - Paris, 11 avril 2013 Portail des maths et PLM 2.0 Jacquelin Charbonnel - Mathrice Journées des DU - Paris, 11 avril 2013 #12;Portail des maths & PLM 2.0 Jacquelin Charbonnel - Journées des DU - Paris, 11 avril 2013 Portail des

  19. Ring opening metathesis polymerization-derived block copolymers bearing chelating ligands: synthesis, metal immobilization and use in hydroformylation under micellar conditions

    PubMed Central

    Pawar, Gajanan M; Weckesser, Jochen

    2010-01-01

    Summary Norborn-5-ene-(N,N-dipyrid-2-yl)carbamide (M1) was copolymerized with exo,exo-[2-(3-ethoxycarbonyl-7-oxabicyclo[2.2.1]hept-5-en-2-carbonyloxy)ethyl]trimethylammonium iodide (M2) using the Schrock catalyst Mo(N-2,6-Me2-C6H3)(CHCMe2Ph)(OCMe(CF3)2)2 [Mo] to yield poly(M1-b-M2). In water, poly(M1-b-M2) forms micelles with a critical micelle-forming concentration (cmc) of 2.8 × 10?6 mol L?1; Reaction of poly(M1-b-M2) with [Rh(COD)Cl]2 (COD = cycloocta-1,5-diene) yields the Rh(I)-loaded block copolymer poly(M1-b-M2)-Rh containing 18 mg of Rh(I)/g of block copolymer with a cmc of 2.2 × 10?6 mol L?1. The Rh-loaded polymer was used for the hydroformylation of 1-octene under micellar conditions. The data obtained were compared to those obtained with a monomeric analogue, i.e. CH3CON(Py)2RhCl(COD) (C1, Py = 2-pyridyl). Using the polymer-supported catalyst under micellar conditions, a significant increase in selectivity, i.e. an increase in the n:iso ratio was accomplished, which could be further enhanced by the addition of excess ligand, e.g., triphenylphosphite. Special features of the micellar catalytic set up are discussed. PMID:20502652

  20. Jahresbericht des Hochschulrates

    E-print Network

    Ferrari, Patrik L.

    1 Jahresbericht 2014 des Hochschulrates der Rheinischen Friedrich-Wilhelm-Universität Bonn #12;2 I Engels als Vorsitzender. Am 15. Juli 2014 wurde Prof. Dr. E. Jürgen Zöllner, auf Vorschlag des. Helmut Schwarz, Dr. Katrin Vernau und Prof. Dr. Dieter Engels, der zum Vorsitzenden dieser Kommission

  1. Direction des Ressources Humaines Bureau du recrutement et des

    E-print Network

    Wolf, Christian

    2015 Contact Direction des Ressources Humaines Bureau du recrutement et des concours Bâtiment Julie Maîtriser au moins une méthode de spécification et de conception . Maîtriser des méthodes et techniques de langages Objet (C++, Java), Web (PHP), SQL, script... . Avoir des compétences en programmation web et dans

  2. Des Moines and Raccoon Rivers, Des Moines, Iowa

    E-print Network

    US Army Corps of Engineers

    Des Moines and Raccoon Rivers, Des Moines, Iowa 18 October 2006 Abstract: The recommended plan opportunities along the Des Moines and Raccoon Rivers in the areas of Birdland Park, Central Place and downtown Additional Information: Mississippi Valley Division Rock Island District Des Moines and Raccoon River Damage

  3. Les bonhommes-foumis Il y a des annes, bien des saisons et bien des jours, vivaient des petits

    E-print Network

    van Tiggelen, Bart

    Les bonhommes-foumis Il y a des années, bien des saisons et bien des jours, vivaient des petits petites colonies sur leur territoire principal ou en territoire éloigné. Un jour, elles se sont retrouvées sur un petit territoire charmant du nom de Cargèse. Les petits bonhommes-fourmis se sont retrouvés

  4. VIE DES RESEAUX Exploration pluridisciplinaire des identits

    E-print Network

    van Tiggelen, Bart

    sous concentration solaire, caractérisée à l'iEs Dans le contexte budgétaire français des prochaines revues LIVRE REVUE PHOTO ©CNRsPhotothèque-FOUCARANAlain,CUMiNALYvan �LAUNEwww.cnrs.fr Cellule solaire

  5. Facult des arts et des sciences Sciences sociales et psychologie | Cartographie de la recherche 2012 TABLE DES MATIRES

    E-print Network

    Montréal, Université de

    #12;Faculté des arts et des sciences ­ Sciences sociales et psychologie | Cartographie de la ..................................................................................................................................................................... 2 La Faculté des arts et des sciences (FAS), c'est....................................................................................... 3 Sciences sociales et psychologie

  6. Liquid films, foams and emulsions

    NASA Astrophysics Data System (ADS)

    Langevin, D.

    1999-06-01

    Studies of thin liquid films, made from surfactant solutions, are presented. The film drainage and the interaction between film surfaces are characterized with an experimental device called "Thin Film Balance". Cases where film stratification is observed will be discussed. These experiments allow to model thin films which form between bubbles and drops in foams and emulsions respectively. Nous présentons des études de films liquides formés à partir de solutions de tensioactifs. Nous avons étudié le drainage et les forces entre surfaces à l'aide d'un dispositif expérimental appelé "Balance à Films". Dans certains cas, on observe des phénomènes de stratification que l'on décrira. Ces expériences permettent de modéliser les films entre bulles et gouttes que l'on rencontre dans les mousses et les émulsions respectivement.

  7. OsH{sub 5}(PMe{sub 2}Ph){sub 3}{sup +}: Structure, reactivity, and its use as a catalyst precursor for olefin hydrogenation and hydroformylation

    SciTech Connect

    Johnson, T.J.; Huffman, J.C.; Caulton, K.G.

    1994-10-26

    OsH{sub 5}L{sub 3}{sup +} (as its BF{sub 4}{sup {minus}} salt; L = PMe{sub 2}Ph) is characterized by neutron diffraction as a dodecahedral pentahydride. However, the H/H separations are as short as 1.49(4) {angstrom}. This cation exchanges OsH with D{sub 2} and is converted by CO to OsH(CO){sub 2}L{sub 3}{sup +}. This cation hydrogenated ethylene (<1 h) at 25 {degrees}C to generate cis mer-OsH(C{sub 2}H{sub 4}){sub 2}L{sub 3}{sup +}, which was characterized by variable-temperature {sup 31}P, {sup 1}H, and {sup 13}C NMR spectroscopy and X-ray diffraction. The orientation of the olefins in this compound is explained using extended Hueckel methods, as is the lack of a structural trans influence on Os-C bond lengths and the reversed kinetic trans effect. Studies with Os/D and C{sub 2}D{sub 4} labeling, as well as trapping of transients with CO and with 1,5-cyclooctadiene, serve to define a reaction mechanism for ethylene hydrogenation, and the pentahydride cation also hydrogenates cyclohexene. In spite of the mutual trans stereochemistry of hydride and ethylene in OsH-(CO)(C{sub 2}H{sub 4})L{sub 3}{sup +} and then more slowly to cis,mer-Os[C(O)Et](CO){sub 2}Lp{sub 3}{sup +}. A variety of isotopic labeling studies prove that the first of these reactions does not involve preequilibrium dissociation of CO, PMe{sub 2}Ph, or C{sub 2}H{sub 4}, nor does it involve bimolecular proton transfer to form the ethyl group. Intramolecular hydrogen migration to bring H cis to C{sub 2}H{sub 4} is consistent with all observations. The carbonyl ligands in OsH(CO){sub 2}L{sub 3}{sup +} are susceptible to nucleophilic attack by solvent in water, to effect the water gas shift reaction. In the presence of water and 1-hexene, Reppe hydroformylation (H{sub 2}O + 2CO + olefin {yields} aldehyde + CO{sub 2}) is catalyzed by OsH(CO)(L{prime})L{sub 3}{sup +} (L{prime} = CO or C{sub 2}H{sub 4}) and by Os(Et)(CO){sub 2}L{sub 3}{sup +}.

  8. Etude theorique et experimentale des evaporateurs de dioxyde de carbone operant dans des conditions de givrage

    NASA Astrophysics Data System (ADS)

    Bendaoud, Adlane Larbi

    Les evaporateurs de refrigeration sont surtout du type tube a ailettes, appeles serpentins, et fonctionnent dans l'une des conditions suivantes: seche, humide ou avec formation de givre. Il a ete demontre que la formation du givre sur la paroi exterieure de l'echangeur engendre une surconsommation energetique a cause des operations de degivrage puisque 15 a 20% seulement de la chaleur produite sert au degivrage tandis que le reste est dissipee dans l'environnement [1]. Avec l'avenement des nouveaux refrigerants, moins nocifs envers l'environnement, l'industrie du froid se trouve penalisee du fait que peu ou pas de composantes mecaniques (compresseur, pompe, echangeur...etc.) adaptees sont disponibles [3]. Il s'agit pour la communaute des frigoristes de combler ce retard technologique en redeveloppant ces composantes mecaniques afin qu'elles soient adaptees aux nouveaux refrigerants. Dans cette optique, et afin de mieux comprendre le comportement thermique des evaporateurs au CO2 fonctionnant dans des conditions seches, qu'un groupe de chercheurs du CanmetENERGIE avaient lance, en 2000, un programme de R & D. Dans le cadre de programme un outil de simulation des evaporateurs au CO2 a ete developpe et un banc d'essai contenant une boucle secondaire de refrigeration utilisant le CO2 comme refrigerant a ete construit. Comme continuite de ce travail de recherche, en 2006 ce meme groupe de recherche a lance un nouveau projet qui consiste a faire une etude theorique et experimentale des evaporateurs au CO2 operants dans des conditions de givrage. Et, c'est exactement dans le cadre de ce projet que se positionne ce travail de these. Ce travail de recherche a ete entrepris pour mieux comprendre le comportement thermique et hydrodynamique des serpentins fonctionnant dans des conditions de givrage, l'effet des circuits de refrigerant ainsi que celui des parametres geometriques et d'operation. Pour cela, un travail theorique supporte par une etude experimentale a ete effectue. Dans la partie theorique, un modele traitant les aspects thermique, hydrodynamique et massique a ete elabore. Sur la base de ce modele a ete ecrit un programme informatique en langage FORTRAN 6.6. Il est base sur la discretisation du serpentin en volumes de controle, est entierement automatise et peut traiter des echangeurs de chaleur avec des circuits de refrigerant complexes pouvant avoir des entrees et sorties multiples ainsi que des bifurcations. La presence simultanee des trois phases thermodynamiques du refrigerant (liquide sous refroidi, fluide sature, vapeur surchauffee) dans le serpentin est aussi prise en charge. Le modele a ete valide pour un fonctionnement avec et sans formation de givre en utilisant des donnees experimentales disponibles dans la litterature et celles obtenues sur le banc d'essai de CanmetENERGIE. Celui-ci a ete mis a jour pour les besoins de la presente recherche et pour cela, un systeme de surchauffe et d'injection de la vapeur d'eau dans une enceinte a tres basse temperature a ete dimensionne, fabrique et installe. Un dispositif de visualisation de la formation de givre, ainsi qu'un equipement de mesure de la temperature, de la pression et de l'humidite relative de l'air ont aussi ete ajoutes. Une fois le modele valide, des simulations numeriques sur le serpentin avec et sans formation de givre ont ete effectuees. Un premier cas de base a servi comme reference pour d'autres cas pour lesquels une etude parametrique sur la geometrie et le fonctionnement a ete menee. Il a ete montre par rapport au cas de base que : 1. la diminution de la densite des ailettes sur des rangees specifiques du serpentin donne une surface minimale (Amin) plus grande, retardant ainsi l'obstruction totale du serpentin par le givre et permet donc un temps de fonctionnement plus grand et une frequence de degivrage plus faible. 2. une bonne configuration de circuit de refrigerant augmente le temps de fonctionnement du serpentin de 200 % et delivre une puissance frigorifique moyenne superieures de 20 % par rapport a celle du cas de base. 3. la diminution d

  9. Rpertoire des emplois en dcembre 2011 Des diplms de Master

    E-print Network

    Jeanjean, Louis

    du texte (UFR SLHS) - Sport langage et intervention (UPFR Sports) - Théâtres et cultures du monde administratif et financier (Entreprise) (IAE) - Management des relations humaines (UFR STGI) - Marketing et) - Sociologie et anthropologie des savoirs et des normes (UFR SLHS) - Sports, loisir, développement territorial

  10. Zoom mtierssur Les mtiers desLes mtiers des

    E-print Network

    de la Londe. DIFFUSION, COMMERCIALISATION, MARKETING Directeur du département: Philippe Gille ONISEP VPC, 12 mail Barthélemy Thimonnier, Lognes, 77437 Marne-la-Vallée Cedex 2 Internet: http (allocation des fréquences, gestion des appels), l'internet (concep- tion des protocoles de communication

  11. Promoter effect of iron on olefin hydroformylation catalyzed by SiO/sub 2/-supported rhodium-iron bimetallic carbonyl clusters: Rh-Fe/sup 3 +/ bimetallic activation of catalytic CO insertion

    SciTech Connect

    Fukuoka, A.; Ichikawa, M.; Hriljac, J. A.; Shriver, D.R.

    1987-11-04

    Rh-Fe bimetallic carbonyl clusters have been employed as precursor for the preparation of Rh-Fe bimetallic catalysts. The structural properties of the Rh-Fe bimetallic cluster supported on SiO/sub 2/ were studied by means of Moessbauer and ir spectroscopy of chemisorbed CO. The results reported for the hydroformylation of ethylene and propylene indicate that the Rh-Fe/sup 3 +/ species derived from SiO/sub 2/-supported Rh-Fe carbonyl clusters are highly active for migratory CO insertion. These catalysts also enhanced the simple hydrogenation reactions. The activity and selectivity of the catalysts is thought to be due to the bi-site interaction with C- and O-bonded CO that is reflected in Fe promotion for C/sub 1/-C/sub 2/ alcohol production from CO and H/sub 2/ catalyzed on the Rh-Fe catalysts. 20 references, 1 table.

  12. The DES Story: Lessons Learned

    Cancer.gov

    Dr. Robert Hoover discusses the DES followup study, which follows diethylstilbestrol (DES) exposed and unexposed mothers, daughters and sons, and granddaughters for adverse health effects resulting from this exposure.

  13. Bimetallic promotion of alcohol production in CO hydrogenation and olefin hydroformylation on RhFe, PtFe, PdFe, and IrFe cluster-derived catalysts

    SciTech Connect

    Fukuoka, Atsushi; Kimura, Takuma; Ichikawa, Masaru ); Kosugi, Nobuhiro; Kuroda, Haruo; Minai, Yoshitaka; Sakai, Yoichi; Tominaga, Tominaga )

    1990-12-01

    Iron-containing bimetallic catalysts were prepared from carbonyl clusters as precursors deposited on SiO{sub 2}. FeRh{sub 4} and Fe{sub 2}Rh{sub 4} cluster-derived catalysts showed high activity and selectivity for formation of ethanol and methanol in CO hydrogenation. Fe{sub 3}Pt{sub 3}, Fe{sub 6}Pd{sub 6}, and FeIr{sub 4} cluster catalysts gave methanol in high selectivity, while Fe-rich Fe{sub 4}Pt and Fe{sub 4}Pd were not selective catalysts. The RhFe cluster catalysts showed improved activity in hydroformylation of olefins; C{sub 4-}alcohols were substantially obtained from C{sub 3}H{sub 6} + CO + H{sub 2}. Moessbauer and EXAFS studies on the Fe{sub 2}Rh{sub 4}/SiO{sub 2} catalyst show that highly dispersed RhFe bimetallic particles are located on the SiO{sub 2} surface, where Fe atoms exist preferentially in the state of Fe{sup 3+} even after H{sub 2} reduction. FTIR spectra of CO chemisorbed on Fe{sub 2}Rh-Fe{sup 3+} sites. Bimetallic promotion of alcohol production in CO hydrogenation and olefin hydroformylation is proposed to originate from the two-site interaction of Rh-Fe{sup 3+} (or Pt-Fe{sup 3+}, Pd-Fe{sup 3+}, Ir-Fe{sup 3+}) sites with CO enhance migratory CO insertion.

  14. An in-situ infrared study of the formation of n- and iso-butyraldehyde from propylene hydroformylation on Rh/SiO[sub 2] and sulfided Rh/SiO[sub 2

    SciTech Connect

    Srinivas, G.; Chuang, S.S. )

    1993-11-01

    In situ infrared (IR) technique has been employed to study the reaction of adsorbed CO on Rh/SiO[sub 2] and S-Rh/SiO[sub 2] with C[sub 3]H[sub 6] and H[sub 2], and to investigate the effect of sulfur on the n- and iso-butyraldehyde selectivities during steady-state propylene hydroformylation. CO adsorption on Rh/SiO[sub 2] results in the formation of linear CO and bridged CO adsorbed on Rh[sup 0] sites, and the gemdicarbonyl on Rh[sup +] sites. CO adsorption on S-Rh/SiO[sub 2] results in a high wavenumber Rh[sup +](CO) species in addition to linear CO adsorbed on Rh[sup 0] and the gem-dicarbonyl adsorbed on Rh[sup +]. Sulfur decreases the rate of CO adsorption and inhibits the formation of bridged CO on Rh/SiO[sub 2]. Pulse CO chemisorption on Rh/SiO[sub 2] and S-Rh/SiO[sub 2] reveals that equilibrium constant for CO adsorption on S-Rh/SiO[sub 2] is smaller than that on Rh/SiO[sub 2] at 303 K. The analogy between homogeneous and heterogeneous hydroformylation suggests that enhancement of the isobutryaldehyde formation by adsorbed sulfur could be due to the spacious environment of the protruding Rh[sup +] ion sites ion the S-Rh/SiO[sub 2] allowing isomerization of n-propyl groups before CO insertion. 56 refs., 11 figs., 3 tabs.

  15. La biogenèse des mélanosomes

    PubMed Central

    Delevoye, Cédric; Giordano, Francesca; van Niel, Guillaume; Raposo, Graça

    2012-01-01

    Les mélanocytes situés à la base de l’épiderme produisent des mélanosomes qui sont transférés aux kératinocytes pour assurer la pigmentation de l’épiderme et sa photoprotection contre les rayons ultraviolets. Les mélanosomes, organites apparentés aux lysosomes, sont le lieu de synthèse et de stockage d’un pigment, la mélanine. Leur formation dépend de protéines mélanosomales qui transitent par les voies de biosynthèse et d’endocytose et exploitent les mécanismes moléculaires du trafic intracellulaire. Les acteurs moléculaires impliqués dans le transport des protéines mélanosomales et la biogenèse des mélanosomes sont la cible de mutations dans des maladies génétiques accompagnées d’hypopigmentation comme l’albinisme et les maladies lysosomales. Les études menées sur les mélanocytes issus de souris modèles de ces maladies permettent de comprendre certaines des étapes-clés de la mélanogenèse ainsi que les dysfonctionnements associés à ces pathologies. De plus, décrypter la mélanogenèse facilite également la compréhension d’autres processus physiologiques, comme l’illustrent les similitudes inattendues avec l’amyloïdogenèse dans les maladies neurodégénératives. PMID:21382323

  16. Architecture des ordinateurs I Prsentation

    E-print Network

    Boyer, Michel

    version anglaise o Structured Computer Organization, 5th edition. page 8IFT1227 ­ Architecture des99-06-09 1 IFT1227 Architecture des ordinateurs I Présentation El Mostapha Aboulhamid Em.aboulhamid@umontreal.ca Université de Montréal page 2IFT1227 ­ Architecture des ordinateurs 1 ­ JP DAVID & EM Aboulhamid Plan de

  17. Des Vents et des Jets Astrophysiques

    NASA Astrophysics Data System (ADS)

    Sauty, C.

    Plasma outflows from a central gravitating object are a widespread phenomenon in astrophysics. They include the solar and stellar winds, jets from Young Stellar Objects, jets from compact stellar objects and extra-galactic jets associated with Active Galactic Nuclei and quasars. Beyond this huge zoology, a common theoretical ground exists. The aim of this review is to present qualitatively the various theories of winds (Part 1) and how different astrophysical domains interplay. A more or less complete catalog of the ideas proposed for explaining the acceleration and the morphologies of winds and jets is intended. All this part avoids getting into any mathematical formalism. Some macroscopic properties of such outflows may be described by solving the time-independent and axisymmetric magnetohydrodynamic equations. This formalism, underlying most of the theories, is presented in Part 2. It helps to introduce quantitatively the free integrals that such systems possess. Those integrals play an important role in the basic physics of acceleration and collimation, in particular the mass loss rate, the angular momentum loss rate and the energy of the magnetic rotator. Most of the difficulty in modelling flows lies in the necessity to cross critical points, characteristic of non linear equations. The physical nature and the location of such critical points is debated because they are the clue towards the resolution. We thus introduce the notions of topology and critical points (Parts 3 and 4) from the simplest hydrodynamic and spherically symmetric case to the most sophisticated, MHD and axisymmetric cases. Particular attention is given to self-similar models which allows to give some general and simple ideas on the problem due to their semi-analytical treatment. With the use of these notions, a more quantitative comparison of the various models is given (Parts 3 and 4), especially on the shape of the flows. It is thus shown that magnetic collimation of winds into jets is a well expected result from the theory. Although, collimation may be conical, paraboloidal or cylindrical (Part 4), cylindrical collimation is the more likely to occur. The shape of outflows may then be used as a tool to predict physical conditions on the flows or on their source. L'éjection continue de plasma autour d'objets massifs est un phénomène largement répandu en astrophysique, que ce soit sous la forme du vent solaire, de vents stellaires, de jets d'étoiles en formation, de jets stellaires autour d'objets compacts ou de jets extra-galactiques. Cette zoologie diversifiée fait pourtant l'objet d'un commun effort de modélisation. Le but de cette revue est d'abord de présenter qualitativement le développement, depuis leur origine, des diverses théories de vents (Partie 1) et l'inter disciplinarité dans ce domaine. Il s'agit d'une énumération, plus ou moins exhaustive, des idées proposées pour expliquer l'accélération et la morphologie des vents et des jets, accompagnée d'une présentation sommaire des aspects observationnels. Cette partie s'abstient de tout aspect faisant appel au formalisme mathématique. Ces écoulements peuvent être décrits, au moins partiellement, en résolvant les équations magnétohydrodynamiques, axisymétriques et stationnaires. Ce formalisme, à la base de la plupart des théories, est exposé dans la Partie 2. Il permet d'introduire quantitativement les intégrales premières qu'un tel système possède. Ces dernières sont amenées à jouer un rôle important dans la compréhension des phénomènes d'accélération ou de collimation, en particulier le taux de perte de masse, le taux de perte de moment angulaire ou l'énergie du rotateur magnétique. La difficulté de modélisation réside dans l'existence de points critiques, propres aux équations non linéaires, qu'il faut franchir. La nature physique et la localisation de ces points critiques fait l'objet d'un débat important car ils sont la clef de voute de la résolution. Nous introduisons donc la notion de topologie des points critiques (Parties 3 et 4

  18. Injectabilite des coulis de ciment dans des milieux fissures

    NASA Astrophysics Data System (ADS)

    Mnif, Thameur

    Le travail presente ici est un bilan du travaux de recherche effectues sur l'injectabilite des coulis de ciment dans lu milieux fissures. Un certain nombre de coulis a base de ciment Portland et microfin ont ete selectionnes afin de caracteriser leur capacite a penetrer des milieux fissures. Une partie des essais a ete menee en laboratoire. L'etude rheologique des differents melanges a permis de tester l'influence de l'ajout de superplastifiant et/ou de fumee de silice sur la distribution granulometrique des coulis et par consequent sur leur capacite a injecter des colonnes de sable simulant un milieu fissure donne. La classe granulometrique d'un coulis, sa stabilite et sa fluidite sont apparus comme les trois facteurs principaux pour la reussite d'une injection. Un facteur de finesse a ete defini au cours de cette etude: base sur la classe granulometrique du ciment et sa stabilite, il peut entrer dans la formulation theorique du debit d'injection avant application sur chantier. La deuxieme et derniere partie de l'etude presente les resultats de deux projets de recherche sur l'injection realises sur chantier. L'injection de dalles de beton fissurees a permis le suivi de l'evolution des pressions avec la distance au point d'injection. L'injection de murs de maconnerie a caractere historique a montre l'importance de la definition de criteres de performance des coulis a utiliser pour traiter un milieu donne et pour un objectif donne. Plusieurs melanges peuvent ainsi etre predefinis et mis a disposition sur le chantier. La complementarite des ciments traditionnels et des ciments microfins devient alors un atout important. Le choix d'utilisation de ces melanges est fonction du terrain rencontre. En conclusion, cette recherche etablit une methodologie pour la selection des coulis a base de ciment et des pressions d'injection en fonction de l'ouverture des fissures ou joints de construction.

  19. Dissolution de la matiere lignocellulosique dans les liquides ioniques

    NASA Astrophysics Data System (ADS)

    Rebiere, Jeremy

    De nos jours, avec la raréfaction des ressources fossiles, le développement de procédés entrant dans le cadre de la chimie verte s'accentue. De plus, ces procédés utilisent comme ressources, des matériaux d'origine végétale, abondants et biodégradables. Au cours de ces 20 dernières années, la littérature utilisant les liquides ioniques (LI) connait une importante croissance. Ces solvants sont de plus en plus employés dans des réactions chimiques classiques. Cependant le coût de leur synthèse en fait un solvant réactionnel cher dont l'application en tant que tel dans l'industrie ne peut être raisonnablement envisagée. Ces liquides ioniques permettent la dissolution des matériaux lignocellulosiques (lignine ou cellulose) et possèdent des propriétés physico-chimiques intéressantes. Nous savons également que la dissolution de la cellulose par des procédés d'hydrolyse classique s'effectue dans des conditions dures, dues à la structure cristalline de la cellulose, (fortes concentrations en acide) qui paraissent limitées pour une utilisation à grande échelle. Il est donc nécessaire de rechercher des méthodes moins onéreuses et plus efficaces écologiquement. S'appuyant sur des recherches démontrant que la dissolution de la cellulose dans les LI, diminue la cristallinité de la cellulose, nous allons chercher à démontrer au cours de ces travaux, la possibilité d'utiliser les LI comme moyen de prétraitement pour la dissolution de la cellulose. Nous allons nous attacher à dissoudre la cellulose, et à étudier les proportions pouvant être dissoutes. Puis nous chercherons à récupérer puis à réutiliser ces LI. Enfin nous cherchons à caractériser les modifications apportées à notre cellulose. Mots Clés liquide ionique, cellulose, cristallinité, réactivité, dissolution, régénération, non-solvant, purification, prétraitement, zone amorphe.

  20. Studiengang:_____________________________________________ Name des/der Stud. Matr. Nr.

    E-print Network

    Wichmann, Felix

    :_____________________________________________ ................................................................. ........................................... Name des/der Stud. Matr. Nr. Titel des Moduls (deutsch

  1. Domino reactions triggered by hydroformylation.

    PubMed

    Petricci, Elena; Cini, Elena

    2013-01-01

    HF reaction represents a selective method for the synthesis of aldehydes starting from alkenes. Because of versatile aldehydes reactivity, it is possible to perform different domino protocols based on contemporary HF, including Michael's reaction, reductive amination, cyclopropanation, lactonization, and many others. This overview reports on the last 5 years' results obtained on this field. PMID:23912442

  2. Colloque "Microstructure et Proprietes des Materiaux" ENPC, 17 et 18 mars 2005 MECANIQUE DES ROCHES EN GEOLOGIE : DES PROCESSUS

    E-print Network

    Fortin, Jérôme

    Colloque "Microstructure et Propri´et´es des Mat´eriaux" ENPC, 17 et 18 mars 2005 MECANIQUE DES.gueguen@ens.fr R´esum´e : Le domaine couvert par la M´ecanique des Roches en G´eologie s'´etend sur des ´echelles 1 Introduction La M´ecanique des roches intervient en G´eologie pour tenter d'apporter des r

  3. Analyse des intensités et filtrage des énergies en émission électronique

    NASA Astrophysics Data System (ADS)

    Duval, P.; Blaise, G.; Henry, L.

    1991-10-01

    A different method for using a dispersive system consisting of a magnetic prism and an electrostatic mirror is proposed. This method allows one to study electron intensities and energies coming from the surface of a sample which has been bombarded by an electron beam of a given energy. Le système dispersif constitué d'un prisme magnétique et d'un miroir électrostatique, utilisé jusqu'à présent en microscopie électronique par transmission pour l'analyse et le filtrage des énergies des électrons transmis à travers une couche mince, peut être adapté pour constituer une nouvelle méthode d'étude des intensités et des énergies des électrons diffusés par la surface d'un échantillon bombardé par un faisceau d'électrons d'énergie choisie.

  4. PREFACE: Functionalized Liquid Liquid Interfaces

    NASA Astrophysics Data System (ADS)

    Girault, Hubert; Kornyshev, Alexei A.; Monroe, Charles W.; Urbakh, Michael

    2007-09-01

    Most natural processes take place at interfaces. For this reason, surface science has been a focal point of modern research. At solid-liquid interfaces one can induce various species to adsorb or react, and thus may study interactions between the substrate and adsorbates, kinetic processes, optical properties, etc. Liquid-liquid interfaces, formed by immiscible liquids such as water and oil, have a number of distinctive features. Both sides of the interface are amenable to detailed physical and chemical analysis. By chemical or electrochemical means, metal or semiconductor nanoparticles can be formed or localised at the interface. Surfactants can be used to tailor surface properties, and also to place organic molecular or supermolecular constructions at the boundary between the liquids. Electric fields can be used to drive ions from one fluid to another, or even change the shape of the interface itself. In many cases, both liquids are optically transparent, making functionalized liquid-liquid interfaces promising for various optical applications based on the transmission or reflection of light. An advantage common to most of these systems is self-assembly; because a liquid-liquid interface is not mechanically constrained like a solid-liquid interface, it can easily access its most stable state, even after it has been driven far from equilibrium. This special issue focuses on four modes of liquid-liquid interfacial functionalization: the controlled adsorption of molecules or nanoparticles, the formation of adlayers or films, electrowetting, and ion transfer or interface-localized reactions. Interfacial adsorption can be driven electrically, chemically, or mechanically. The liquid-liquid interface can be used to study how anisotropic particles orient at a surface under the influence of a field, how surfactants interact with other adsorbates, and how nanoparticles aggregate; the transparency of the interface also makes the chirality of organic adsorbates amenable to optical study. Film formation goes a step beyond adsorption; some surfactants form monolayers or multilayers at the interface. A polymer microfilm or a polymer-particle matrix can be synthesized at the liquid-liquid boundary. Such films exhibit unique adsorption and ion-intercalation properties of their own. Electrowetting refers broadly to the phenomenon in which an applied voltage modulates the shape of a liquid-liquid interface, essentially by altering the surface tension. Electric fields can be used to induce droplets on solid substrates to change shape, or to affect the structure of liquid-liquid emulsions. Various chemical reactions can be performed at the liquid-liquid boundary. Liquid-liquid microelectrodes allow detailed study of ion-transfer kinetics at the interface. Photochemical processes can also be used to control the conformations of molecules adsorbed at the interface. But how much precise control do we actually have on the state of the interfacial region? Several contributions to this issue address a system which has been studied for decades in electrochemistry, but remains essentially unfamilar to physicists. This is the interface between two immiscible electrolytic solutions (ITIES), a progressing interdisciplinary field in which condensed-matter physics and physical chemistry meet molecular electrochemistry. Why is it so exciting? The reason is simple. The ITIES is chargeable: when positioned between two electrodes it can be polarized, and back- to-back electrical double layers form on both sides of the liquid-liquid interface. Importantly, the term immiscible refers not only to oil and water but also to the electrolytes. Inorganic electrolytes, such as alkali halides, tend to stay in water, whereas organic electrolytes, such as tetrabutylammonium tetraphenylborate, stay in oil. This behaviour arises because energies of the order of 0.2-0.3 eV are needed to drive ions across the interface. As long as these free energies of transfer are not exceeded by the external potential bias, the ITIES works as an 'electrode'; there is no traffic of ions

  5. Liquid Metals

    NASA Astrophysics Data System (ADS)

    March, Norman Henry

    1990-10-01

    This comprehensive, research level introduction to the theory of liquid metals presents the concepts needed to understand the properties of these metals starting with a survey of the basic experimental facts. The quantitative theory of liquid pair correlation functions, effective ion-ion interactions, thermodynamic properties and electronic and atomic transport is then developed. The book also explores inelastic neutron scattering from bulk liquid metals, critical behavior, magnetism, the present understanding of the liquid metal surface, binary liquid metals, shock wave studies, liquid hydrogen plasmas and the constitution of red star giants. This is an informative text for advanced postgraduate students and researchers in condensed matter physics, theoretical physics, physical chemistry and theoretical chemistry.

  6. rencontre du non-lineaire 2000 1 Sur la similitude des morphologies des nervations des feuilles et de

    E-print Network

    Adda-Bedia, Mokhtar

    de celles des fractures Y. Couder*, L. Pauchard**, C. Allain**, M. Adda-Bedia* et S. Douady* *LPS, 24´esentent les formes de ces nervations diff`erent des formes engendr´ees lors de croissances dans des champs possible effet sur la diff´erentiation des nervures. 1 Introduction Les figures form´ees par les nervures

  7. Metal-assisted hydroformylation on a SiO sub 2 -attached Rh dimer. In situ EXAFS and FT-IR observations of the dynamic behaviors of the dimer site

    SciTech Connect

    Asakura, Kiyotaka; Kitamura-Bando, Kyoko; Iwasawa, Yasuhiro ); Arakawa, Hironori ); Isobe, Kiyoshi )

    1990-12-05

    trans-(Rh(C{sub 5}Me{sub 5})(CH{sub 3})){sub 2}({mu}-CH{sub 2}){sub 2} was supported on the SiO{sub 2} surface by the reaction with OH groups of SiO{sub 2} at 313 K, followed by evacuation at 373 K. In this attaching reaction, the Rh dimer complexes were bound to the SiO{sub 2} surface through Rh-O(surface) bonds, losing one CH{sub 3} ligand and one C{sub 5}Me{sub 5} ligand per Rh dimer. The attached Rh dimers were found to be more active and selective than a conventionally prepared Rh/SiO{sub 2} catalyst. The structure change of the Rh dimer sites in each reaction step for catalytic hydroformylation was followed by means of in-situ FT-IR and in situ EXAFS techniques. The Rh-Rh bond in the attached Rh dimers (Rh-Rh = 0.262 nm) was cleaved by CO adsorption to form monomer pairs (Rh(C{sub 2}H{sub 5})(CO){sub 2}(O-Si) + Rh(C{sub 5}Me{sub 5})(O-Si)). Heating the monomer pairs to 423 K under vacuum resulted in CO insertion, with new peaks exhibited at 1,710 and 1,394 cm{sup {minus}1} due to the acyl ligand.

  8. Juillet 2014 Sur les plages des Canaries, des grains de sable...

    E-print Network

    Huck, Thierry

    1 Juillet 2014 Sur les plages des Canaries, des grains de sable... et des micro-plastiques Les îles Canaries ne sont pas à l'abri de la pollution par les matières plastiques. Mais la localisation des plages'est focalisée sur une des composantes du problème (les micro-plastiques), une région côtière (les îles Canaries

  9. Modlisation des connaissances gographiques Pr. Robert Laurini

    E-print Network

    Laurini, Robert

    Modélisation des connaissances géographiques 1 Pr. Robert Laurini « 80 % des données existantes ont;Modélisation des connaissances géographiques 2 Pr. Robert Laurini 1.1 ­ Modélisation des objets géographiques géographiques 3 Pr. Robert Laurini Géodésie · La terre n'est pas tout à fait ronde ­ ellipsoïde ­ altitude

  10. FLORENT MARTOS Structuration ecologique et evolutive des

    E-print Network

    FLORENT MARTOS Structuration ´ecologique et ´evolutive des symbioses mycorhiziennes des orchid th`ese intitul´ee: Structuration ´ecologique et ´evolutive des symbioses mycorhiziennes des orchid`eces d'orchid´ees actuelles qui d´ependent toutes de champignons mycorhiziens pour accomplir leur cycle

  11. Sciences des aliments Mention : Nutrition, sant, aliments

    E-print Network

    Sart, Remi

    Sciences des aliments Mention : Nutrition, santé, aliments Nature de la formation : Diplôme-Ferrand) #12;2 Sciences des aliments UFR Sciences et Technologies PRÉSENTATION Objectifs Mention Nutrition scientifiques et techniques solides dans le domaine de la Nutrition, des Sciences des Aliments et de la Santé

  12. La structure de l'eau liquide: Une etude thermique par spectroscopie infrarouge

    NASA Astrophysics Data System (ADS)

    Larouche, Pascal

    Le probleme de la structure de l'eau liquide est important car l'eau est le liquide le plus present sur Terre, et complexe, la quete d'un modele precis pour decrire comment fonctionne ce liquide ayant debute des la fin du dix-neuvieme siecle. Cette etude aborde ce probleme en etudiant l'effet de l'augmentation de la temperature sur H2O et D 2O purs a l'aide de la spectroscopie infrarouge. L'intervalle de temperatures scrute est 29--93.1°C. Les spectres enregistres sont des spectres MIR-ATR entre 650 et 6000 cm-1 . L'analyse par facteurs de ces donnees permet de montrer que deux et seulement deux facteurs principaux sont necessaires pour decomposer tous les spectres experimentaux. Ces resultats sont confirmes grace a l'analyse par facteurs de spectres de la region FIR. Par la suite, la transformation en spectres de la partie reelle n et imaginaire k de l'indice de refraction permet de combiner les donnees des regions MIR et FIR. Une fois ce calcul termine, les spectres de transmission complets de H 2O et D2O entre 25 et 90°C sont connus. Ils sont ensuite utilises pour calculer par extrapolation le spectre des especes constituant l'eau liquide, puis leur abondance en fonction de la temperature. L'extrapolation de ces abondances montre que les especes correspondent a des temperatures limites de --18 et 122°C. Par la suite, la decomposition gaussienne des spectres d'especes met en evidence la riche structure de ces objets et permet de demontrer que l'apparent deplacement du massif d'absorption OH (OD) est produit par une variation de l'intensite des bandes et non pas de leur deplacement. L'examen attentif des spectres des especes prouve qu'il n'y a pas de OH libres crees par l'augmentation de la temperature: meme a 93.1°C, chaque molecule possede quatre liens-H. Ces conclusions sont de plus confirmees par une analyse thermodynamique du passage des molecules de la phase solide a la phase gazeuse. Pour diversifier la nature des resultats experimentaux utilises, des mesures de diffraction des rayons X ont aussi ete analysees. Les abondances tirees de l'analyse par facteurs des spectres infrarouges permettent de calculer les fonctions de distributions radiales des deux especes. Ces fonctions offrent la possibilite de connaitre les distances relatives entre les atomes. Avec ces distances en main, l'architecture des deux especes peut etre schematisee. Ces resultats originaux, combines a ceux issus de la spectroscopie infrarouge, permettent de montrer que la premiere espece est bien organisee, c'est-a-dire que le cube defini par un atome d'oxygene et les quatre autres atomes d'oxygene avec lesquels il est en liens-H est regulier, alors que pour l'espece chaude, les dimensions du cubes sont irregulieres. La comparaison entre les deux especes montre qu'elles etablissent toujours quatre liens-H et que leurs differences resident uniquement dans la geometrie des cubes. Finalement, deux hypotheses sont formulees comme fondement d'un modele de la structure de l'eau liquide. Premierement, l'empilement des cubes des deux especes permet de representer l'eau a toutes les temperatures, l'espece froide etant garante de la stabilite du liquide, alors que l'espece chaude a un effet destabilisant; et deuxiemement, le saut du proton stabilise les liens-H, de telle sorte que lorsque l'espece chaude devient trop abondante, ces defauts provoquent un arret des sauts de protons et les liens-H ainsi affaiblis se brisent et le liquide s'evapore.

  13. Liquid pearls

    E-print Network

    Bremond, Nicolas; Bibette, Jérôme

    2010-01-01

    This fluid dynamics video reports how to form liquid core capsules having a thin hydrogel elastic membrane named liquid pearls. These fish-egg like structures are initially made of a millimetric liquid drop, aqueous or not, coated with an aqueous liquid film containing sodium alginate that gels once the double drop enters a calcium chloride bath. The creation of such pearls with micrometer thick membrane requires to suppress mixing until gelling takes place. Here, we show that superimposing a two dimensional surfactant precipitation at the interface confers a transient rigidity that can damp the shear induced instability at impact. Based on this, pearls containing almost any type of liquids can be created. The video focuses on the dynamics of the entry of the compound drop into the gelling bath.

  14. Sécurité au-delà des mythes et des croyances

    ScienceCinema

    None

    2011-10-06

    Présentation orale en français, support visuel en français et en anglais. La pire des failles de sécurité est l'impression de sécurité. Le décalage entre la compréhension que l?on a des technologies utilisées, et leurs potentiels réels, ainsi que l'impact potentiellement négatif qu'elles peuvent avoir sur nos vies, n'est pas toujours compris, ou pris en compte par la plupart d'entre-nous. On se contente de nos perceptions pour ne pas avoir à se confronter à la réalité... Alors qu'en est-il vraiment ? En matière de sécurité qui de l'humain ou des technologies a le contrôle ?

  15. DYNAMIQUE DES SYST ` EMES D'ISOM '

    E-print Network

    Gaboriau, Damien

    DYNAMIQUE DES SYST ` EMES D'ISOM ' ETRIES : SUR LES BOUTS DES ORBITES Damien Gaboriau Un syst`eme d'isom ; ' 2 ; : : : ; ' k d'isom'etries entre sous­intervalles ferm'es de D. Ces objets sont des syst : celui des actions de groupes par isom'etries sur des arbres r'eels. Un arbre r'eel est un espace m

  16. Fonction diélectrique des milieux inhomogènes

    NASA Astrophysics Data System (ADS)

    Berthier, Serge

    This review article is based on the thesis of Berthier — Laboratoire d'Optique des solides, Université P. et M. Curie— and on various contributions or ulterior works. Its aim is to present a critical and detailed review of the main theories of the optical dielectric function of inhomogeneous media. Together with a mathematical description of the theories, we give a physical interpretation of the results and the practical limits of validity. Each theory is compared to experimental results and other theoretical predictions as well. This study is introduced by theoretical reminders about the electric polarization and considerations about the physical meaning of some fundamental parameters when going from a microscopic to a macroscopic point of view. Cette revue est tirée de la thèse de Berthier préparée au Laboratoire d'Optique des Solides, Université P. et M. Curie, ainsi que des travaux qui lui font suite (thèse en préparation de Driss-Khodja) ou de ceux menés parallèlement (systèmes 2D) par d'autres membres de l'équipe. Son ambition est de présenter une étude approfondie et critique des différentes théories de la fonction diélectrique optique des milieux inhomogènes à trois dimensions. Après une description mathématique détaillée des principales théories, nous donnons une interprétation physique des résultats et les limites concrètes d'utilisation de chacune d'elles. Chaque grande théorie est confrontée à la fois à des résultats expérimentaux et aux prédictions des autres théories. Cette étude est précédée de rappels théoriques sur la polarisation électrique et de considérations sur la signification réelle de certains paramètres lors du passage d'un système microscopique isolé à un système macroscopique aléatoire.

  17. Hydroformylation of the C triple bond C bond of (C sub 5 H sub 5 )(PMe sub 3 ) sub 2 Ru-C triple bond C-CH sub 3 by HRe(CO) sub 5 to give an. eta. sup 1 -aldehyde complex of rhenium

    SciTech Connect

    Bullock, R.M.; Ricci, J.S.; Szalda, D.J. )

    1989-03-29

    The chemistry of aldehydes bonded to transition metals is not well-developed but has been attracting increasing attention. Most of the previously reported aldehyde complexes exhibit {eta}{sup 2}({pi})-bonding. The authors report an unprecedented hydroformylation of the C{triple bond}C bond of a metal alkynyl complex by a metal carbonyl hydride, which results in an {alpha},{beta}-unsaturated aldehyde {eta}{sup 1}({sigma})-bonded to Re{sub 2}(CO){sub 9}.

  18. Rgles administratives Carrefour des arts et des sciences

    E-print Network

    Montréal, Université de

    , contrat et responsabilités Les demandes de réservation Frais de location, contrat et responsabilités Contrat - Le locataire doit obligatoirement signer le contrat de location disponible sur le site du Carrefour des arts et

  19. Des widgets aux comets pour la Plasticit des Systmes Interactifs

    E-print Network

    Des widgets aux comets pour la Plasticité des Systèmes Interactifs From widgets to comets utilisabilité. L'article propose une nouvelle génération de widgets, les « comets » (COntext Mouldable widgETs), pour la construction de systèmes interactifs plastiques. Une comet est, par définition, un widget

  20. Fiabilité des structures mécaniques adaptatives: effet de la panne des actionneurs ou des capteurs sur la stabilité

    NASA Astrophysics Data System (ADS)

    Fall, H.; Charon, W.; Kouta, R.

    2002-12-01

    Ces dernières décennies, des activités significatives dans le monde étaient dirigées autour du contrôle actif. Le but de ces recherches était essentiellement d'améliorer les performances, la fiabilité et la sécurité des systèmes. Notamment dans le cas des structures soumises à des vibrations aléatoires. D'importants travaux ont été consacré à l'utilisation des “matériaux intelligents” comme capteurs et actionneurs. Cette article propose l'analyse de la fiabilité des systèmes mécaniques en étudiant les pannes des actionneurs ou des capteurs. L'effet de ces pannes sur la stabilité et la performance du système y est démontré. Les méthodologies de conception y sont rappelées. Des exemples numériques sont fournis à travers le contrôle d'un panneau sous chargement dynamique pour illustrer la méthode proposée.

  1. La greffe de peau totale dans le traitement des séquelles de brûlures de la main et des doigts: A propos de 84 cas

    PubMed Central

    Boukind, S.; Droussi, H.; Elatiqi, O.K.; Dlimi, M.; Dhaidah, O.; Ejjiyar, M.; Quaboul, M.; Dehhaze, A.; Fkhar, S.; Elamrani, D.; Benchamkha, Y.; Ettalbi, S.

    2014-01-01

    Summary Nous avons mené une étude rétrospective s’étendant de septembre 2004 à septembre 2012 sur les données de à propos de 84 patients présentant des séquelles de brûlure majeures de la main. Ces patients étaient traités chirurgicalement par une greffe de peau totale. Le but de cette étude est, donc, d’insister sur la simplicité de cette technique et surtout son efficacité et sa fiabilité. L’âge moyen de la survenue de la brûlure était de 4 ans. L’âge moyen de nos patients était de 18,3 ans (2-62 ans), avec prédominance masculine dans 60% des cas. L’agent causal le plus fréquent était un agent thermique - le plus souvent un liquide chaud (56%). Le délai moyen entre la fin de la cicatrisation et la prise en charge des séquelles était de 36 mois (2 mois - 16 ans). Dans 69 cas (82.5%), les lésions étaient localisées au niveau de la face palmaire de la main. Les séquelles ont été dominées par les rétractions digitales (65%) dont le déficit fonctionnel est évident. Une greffe de peau totale a été réalisée chez tous nos patients après libération des brides et excision des placards cicatriciels. Les rétractions commissurales ont été traitées par des plasties en Z. Dans 95% des cas, le prélèvement de peau totale était réalisé au niveau du pli inguinal. Le recul moyen était de 5,5 ans (1-8 ans). 11 patients ont été perdus de vu. Les résultats après cicatrisation complète et rééducation ont été jugés satisfaisants (bons) dans 62 cas (85%), et assez bons dans 11 cas (15%). Un traitement initial bien conduit et effectué dans les meilleures conditions permet non seulement de réduire le nombre de séquelles des brûlures mais encore de les rendre moins sévères. PMID:26336368

  2. Liquid Bridge

    NASA Technical Reports Server (NTRS)

    1996-01-01

    Crystal Growth in magnetic fields, a float-zone sample, the surface tension of the melt keeps the sample suspended between the sample rods in the furnace forming an actual liquid bridge. Principal Investigator: Dr. Frank Szofran

  3. des sciences Dlai de candidature

    E-print Network

    Halazonetis, Thanos

    faculté des sciences Délai de candidature: Chaque année au 15 mars* Un montant de CHF 10 000.- à 15 archaeology, geology, environmental sciences, pharmacy, and neurosciences. There is also the possibility

  4. Information -Communication Communication des entreprises

    E-print Network

    Sart, Remi

    Information - Communication 2 PARCOURS Communication des entreprises Communication et solidarité;2 Information - Communication UFR Langues Appliquées, Commerce et Communication PRÉSENTATION Objectifs La Licence Information et communication est destinée aux étudiants qui souhaitent suivre un parcours

  5. Jahresbericht des Instituts fr Kognitionswissenschaft

    E-print Network

    Kallenrode, May-Britt

    die Arbeitsgruppe Philosophie des Geistes und der Kognition. Darüber hinaus wurde Prof. Dr. Robert C. Richardson (Cincinnati) das erste und landesweit einzige Gervinus-Fellowship zugesprochen, der damit ab 2008

  6. Thorie des probabilits LAVOISIER, 2008

    E-print Network

    Rioul, Olivier

    Théorie des probabilités #12;© LAVOISIER, 2008 LAVOISIER 11, rue Lavoisier 75008 Paris www.hermes-science.com www.lavoisier.fr ISBN 978-2-7462-1720-1 ISSN 1952­2401 Le Code de la propriété intellectuelle n

  7. Comprendre le langage des toiles

    E-print Network

    Le Coroller, Hervé

    spectre. #12;Un spectre dans la nature Le spectre le plus simple est l'arc- en a expliqué l'origine de l'arc-en-ciel. #12;Le secret des spectres Mais il a fallu'est au début du 19ème siècle que l'on a découvert le secret des spectres

  8. Liquid Crystals

    NASA Technical Reports Server (NTRS)

    1990-01-01

    Thermochromic liquid crystals, or TLCs, are a type of liquid crystals that react to changes in temperature by changing color. The Hallcrest/NASA collaboration involved development of a new way to visualize boundary layer transition in flight and in wind tunnel testing of aircraft wing and body surfaces. TLCs offered a new and potentially better method of visualizing the boundary layer transition in flight. Hallcrest provided a liquid crystal formulation technique that afforded great control over the sensitivity of the liquid crystals to varying conditions. Method is of great use to industry, government and universities for aerodynamic and hydrodynamic testing. Company's principal line is temperature indicating devices for industrial use, such as non-destructive testing and flaw detection in electric/electronic systems, medical application, such as diagnostic systems, for retail sale, such as room, refrigerator, baby bath and aquarium thermometers, and for advertising and promotion specials. Additionally, Hallcrest manufactures TLC mixtures for cosmetic applications, and liquid crystal battery tester for Duracell batteries.

  9. SOLUBILITIES OF CO AND H2 IN NEAT AND CO2-EXPANDED HYDROFORMYLATION REACTION MIXTURES CONTAINING 1-OCTENE AND NONANAL UP TO 80 °C AND 90 BARS

    E-print Network

    Xie, Zhuanzhuan

    2009-01-01

    control at 40 ?C and 57 bar In a typical run, the cell is first evacuated down to a subambient pressure and pre- flushed with designated gas for several times to remove any residue air. Predetermined amount of the liquid mixture is syringed into the cell... the vacuum calibration method by constructing an experimental unit (Figure 2.7) similar to the one described in Thompson (1977). The calibration procedure involves evacuating a gas sampling valve by a vacuum pump to -29 in Hg (-0.97 atm) prior to each...

  10. HOMOGENEOUS CATALYSIS AND MASS TRANSFER IN BIPHASIC IONIC LIQUID SYSTEMS WITH COMPRESSED CO2 AND ORGANIC COMPOUNDS

    E-print Network

    Ahosseini, Azita

    that are practiced in industry, hydroformylation and hydrogenation of 1-octene, have been selected. In order to investigate the effect of CO2 pressure on controlling the reaction over the mass transfer or kinetic zones, thorough studies have been arranged...

  11. Structure, caractrisation et comportement mcanique des failles sismiques : Etude des pseudotachylites et gouges

    E-print Network

    Demouchy, Sylvie

    Structure, caractérisation et comportement mécanique des failles sismiques : Etude des pseudotachylites et gouges Résumé L'objectif de ce projet est de mieux caractériser la structure et la formation des processus de formation des failles actives en prenant comme objet d'étude les gouges de failles et

  12. Nr. 057 / 2014 // 3. April 2014 Knstlerische Darstellung des ,,Giant impact", des Aufpralls eines kleineren

    E-print Network

    Schittkowski, Klaus

    Nr. 057 / 2014 // 3. April 2014 1/7 Künstlerische Darstellung des ,,Giant impact", des Aufpralls freundlicher Genehmigung des NASA/Jet Propulsion Labors am California Institute of Technology. In ,,Nature- zeichnet. Der ,,Giant impact" und seine Folgen: Die Entstehung des Mondes und Veränderungen im Erdmantel

  13. Des Lacs River and Souris River

    USGS Multimedia Gallery

     The Des Lacs River coming in to the Souris River. Des Lacs River is the darker water, which is sediment and the Souris River is the lighter water. >Photo taken by USGS personnel on a Civil Air Patrol flight....

  14. Macromolecular liquids

    SciTech Connect

    Safinya, C.R.; Safran, S.A. ); Pincus, P.A. )

    1990-01-01

    Liquids include a broad range of material systems which are of high scientific and technological interest. Generally speaking, these are partially ordered or disordered phases where the individual molecular species have organized themselves on length scales which are larger than simple fluids, typically between 10 Angstroms and several microns. The specific systems reported on in this book include membranes, microemulsions, micelles, liquid crystals, colloidal suspensions, and polymers. They have a major impact on a broad spectrum of technological industries such as displays, plastics, soap and detergents, chemicals and petroleum, and pharmaceuticals.

  15. Peste des petits ruminants

    PubMed Central

    Parida, S.; Muniraju, M.; Mahapatra, M.; Muthuchelvan, D.; Buczkowski, H.; Banyard, A.C.

    2015-01-01

    Peste des petits ruminants virus causes a highly infectious disease of small ruminants that is endemic across Africa, the Middle East and large regions of Asia. The virus is considered to be a major obstacle to the development of sustainable agriculture across the developing world and has recently been targeted by the World Organisation for Animal Health (OIE) and the Food and Agriculture Organisation (FAO) for eradication with the aim of global elimination of the disease by 2030. Fundamentally, the vaccines required to successfully achieve this goal are currently available, but the availability of novel vaccine preparations to also fulfill the requisite for differentiation between infected and vaccinated animals (DIVA) may reduce the time taken and the financial costs of serological surveillance in the later stages of any eradication campaign. Here, we overview what is currently known about the virus, with reference to its origin, updated global circulation, molecular evolution, diagnostic tools and vaccines currently available to combat the disease. Further, we comment on recent developments in our knowledge of various recombinant vaccines and on the potential for the development of novel multivalent vaccines for small ruminants. PMID:26443889

  16. Peste des petits ruminants.

    PubMed

    Parida, S; Muniraju, M; Mahapatra, M; Muthuchelvan, D; Buczkowski, H; Banyard, A C

    2015-12-14

    Peste des petits ruminants virus causes a highly infectious disease of small ruminants that is endemic across Africa, the Middle East and large regions of Asia. The virus is considered to be a major obstacle to the development of sustainable agriculture across the developing world and has recently been targeted by the World Organisation for Animal Health (OIE) and the Food and Agriculture Organisation (FAO) for eradication with the aim of global elimination of the disease by 2030. Fundamentally, the vaccines required to successfully achieve this goal are currently available, but the availability of novel vaccine preparations to also fulfill the requisite for differentiation between infected and vaccinated animals (DIVA) may reduce the time taken and the financial costs of serological surveillance in the later stages of any eradication campaign. Here, we overview what is currently known about the virus, with reference to its origin, updated global circulation, molecular evolution, diagnostic tools and vaccines currently available to combat the disease. Further, we comment on recent developments in our knowledge of various recombinant vaccines and on the potential for the development of novel multivalent vaccines for small ruminants. PMID:26443889

  17. Diffusion incohérente des neutrons : modèles analytiques pour la dynamique interne des protéines

    NASA Astrophysics Data System (ADS)

    Bicout, D. J.

    2005-11-01

    La dynamique interne des protéines joue un rôle central dans la stabilité, la fonction et l'activité biologique de ces biomolécules. Il est maintenant établi que les fluctuations d'états conformationnels des protéines influencent fortement la plupart des réactions biochimiques et s'accompagnent d'une augmentation brutale des déplacements carrés moyens des atomes au dessus de la température de la transition dynamique. Dans cette contribution, nous présentons une revue critique de quelques modèles théoriques couramment utilisés dans la littérature pour l'analyse des mouvements internes des protéines et la description de la transition dynamique.

  18. Un accumulateur echangeur de chaleur hybride pour la gestion simultanee des energies solaire et electrique

    NASA Astrophysics Data System (ADS)

    Ait Hammou, Zouhair

    Cette etude porte sur la conception d'un accumulateur echangeur de chaleur hybride (AECH) pour la gestion simultanee des energies solaire et electrique. Un modele mathematique reposant sur les equations de conservation de la quantite d'energie est expose. Il est developpe pour tester differents materiaux de stockage, entre autres, les materiaux a changement de phase (solide/liquide) et les materiaux de stockage sensible. Un code de calcul est mis en eeuvre sur ordinateur, puis valide a l'aide des resultats analytiques et numeriques de la litterature. En parallele, un prototype experimental a echelle reduite est concu au laboratoire afin de valider le code de calcul. Des simulations sont effectuees pour etudier les effets des parametres de conception et des materiaux de stockage sur le comportement thermique de l'AECH et sur la consommation d'energie electrique. Les resultats des simulations sur quatre mois d'hiver montrent que la paraffine n-octadecane et l'acide caprique sont deux candidats souhaitables pour le stockage d'energie destine au chauffage des habitats. L'utilisation de ces deux materiaux dans l'AECH permet de reduire la consommation d'energie electrique de 32% et d'aplanir le probleme de pointe electrique puisque 90% de l'energie electrique est consommee durant les heures creuses. En plus, en adoptant un tarif preferentiel, le calcul des couts lies a la consommation d'energie electrique montre que le consommateur adoptant ce systeme beneficie d'une reduction de 50% de la facture d'electricite.

  19. Alcohol based-deep eutectic solvent (DES) as an alternative green additive to increase rotenone yield

    NASA Astrophysics Data System (ADS)

    Othman, Zetty Shafiqa; Hassan, Nur Hasyareeda; Zubairi, Saiful Irwan

    2015-09-01

    Deep eutectic solvents (DESs) are basically molten salts that interact by forming hydrogen bonds between two added components at a ratio where eutectic point reaches a melting point lower than that of each individual component. Their remarkable physicochemical properties (similar to ionic liquids) with remarkable green properties, low cost and easy handling make them a growing interest in many fields of research. Therefore, the objective of pursuing this study is to analyze the potential of alcohol-based DES as an extraction medium for rotenone extraction from Derris elliptica roots. DES was prepared by a combination of choline chloride, ChCl and 1, 4-butanediol at a ratio of 1/5. The structure of elucidation of DES was analyzed using FTIR, 1H-NMR and 13C-NMR. Normal soaking extraction (NSE) method was carried out for 14 hours using seven different types of solvent systems of (1) acetone; (2) methanol; (3) acetonitrile; (4) DES; (5) DES + methanol; (6) DES + acetonitrile; and (7) [BMIM] OTf + acetone. Next, the yield of rotenone, % (w/w), and its concentration (mg/ml) in dried roots were quantitatively determined by means of RP-HPLC. The results showed that a binary solvent system of [BMIM] OTf + acetone and DES + acetonitrile was the best solvent system combination as compared to other solvent systems. It contributed to the highest rotenone content of 0.84 ± 0.05% (w/w) (1.09 ± 0.06 mg/ml) and 0.84 ± 0.02% (w/w) (1.03 ± 0.01 mg/ml) after 14 hours of exhaustive extraction time. In conclusion, a combination of the DES with a selective organic solvent has been proven to have a similar potential and efficiency as of ILs in extracting bioactive constituents in the phytochemical extraction process.

  20. L'astronomie des Anciens

    NASA Astrophysics Data System (ADS)

    Nazé, Yaël

    2009-04-01

    Quelle que soit la civilisation à laquelle il appartient, l'être humain cherche dans le ciel des réponses aux questions qu'il se pose sur son origine, son avenir et sa finalité. Le premier mérite de ce livre est de nous rappeler que l'astronomie a commencé ainsi à travers les mythes célestes imaginés par les Anciens pour expliquer l'ordre du monde et la place qu'ils y occupaient. Mais les savoirs astronomiques passés étaient loin d'être négligeables et certainement pas limités aux seuls travaux des Grecs : c'est ce que l'auteur montre à travers une passionnante enquête, de Stonehenge à Gizeh en passant par Pékin et Mexico, fondée sur l'étude des monuments anciens et des sources écrites encore accessibles. Les tablettes mésopotamiennes, les annales chinoises, les chroniques médiévales, etc. sont en outre d'une singulière utilité pour les astronomes modernes : comment sinon remonter aux variations de la durée du jour au cours des siècles, ou percer la nature de l'explosion qui a frappé tant d'observateurs en 1054 ? Ce livre offre un voyage magnifiquement illustré à travers les âges, entre astronomie et archéologie.

  1. Exploration des mécanismes de repliement des protéines par dynamique moléculaire

    NASA Astrophysics Data System (ADS)

    Gilquin, B.

    2005-11-01

    Comment se replient les protéines? Cette question est ancienne. En introduction nous rappellerons ce qu'est le paradoxe de Levinthal et comment on est passé de la notion de chemin de repliement à la notion de paysage énergétique. Les simulations de dynamique moléculaire ont permis d'aborder la compréhension du processus de repliement au niveau atomique. Cependant l'échelle de temps des processus de repliement (de l'ordre de la milliseconde) n'est pas accessible aux simulations numériques (de l'ordre de la nanoseconde). Plusieurs auteurs ont donc proposé de simuler le dépliement des protéines par dynamique moléculaire. En admettant le principe de micro-réversibilité l'étude du processus de dépliement renseigne sur celui de repliement. Cependant, il est nécessaire d'accélérer le dépliement en introduisant un biais afin que les états dépliées soient accessibles aux échelles de temps des simulations. Nous présenterons un exemple de ce qui a été réalise dans le cas de l'étude de protéines de petite taille suivant un repliement simple, globalement à deux états. Nous présenterons ensuite ce que nous avons réalisé dans le cas d'une protéine de taille plus importante et pour laquelle le processus de repliement est plus complexe car il existe un intermédiaire transitoire de repliement. C'est le cas du lysozyme pour lequel les simulations de dépliement permettent d'accéder au mécanisme atomique de repliement et de comprendre pourquoi des mutants de cette protéine se replient plus lentement et forment des fibres amyloïdiques. Ainsi les intermédiaires de repliement seraient à l'origine de formes pathogènes des protéines observées dans les maladies neuro-dégéneratives. Enfin nous montrerons comment à partir de plusieurs simulations longues de dynamique moléculaire, le paysage énergétique pour de petites protéines peut être calculé.

  2. Pseudomonas aeruginosa DesB Promotes Staphylococcus aureus Growth Inhibition in Coculture by Controlling the Synthesis of HAQs

    PubMed Central

    Kim, Sejeong; Yoon, Yohan; Choi, Kyoung-Hee

    2015-01-01

    Pseudomonas aeruginosa is a pathogen that can cause serious infections and usually coexists with other pathogens, such as Staphylococcus aureus. Virulence factors are important for maintaining a presence of the organisms in these multispecies environments, and DesB plays an important role in P. aeruginosa virulence. Therefore, we investigated the effect of DesB on S. aureus reduction under competitive situation. Liquid cultures of P. aeruginosa wild type (WT) and its desB mutant were spotted on agar plates containing S. aureus, and the size of the clear zones was compared. In addition, interbacterial competition between P. aeruginosa and S. aureus was observed over time during planktonic coculture. The transcriptional profiles of the WT and desB mutant were compared by qRT-PCR and microarray to determine the role of DesB in S. aureus reduction at the molecular level. As a result, the clear zone was smaller for the desB mutant than for P. aeruginosa PAO1 (WT), and in planktonic coculture, the number of S. aureus cells was reduced in the desB mutant. qRT-PCR and microarray revealed that the expression of MvfR-controlled pqsA-E and phnAB operons was significantly decreased, but the mexEF-oprN operon was highly expressed. The results indicate that intracellular levels of 4-hydroxy-2-heptylquinoline (HHQ), a ligand of MvfR, are reduced due to MexEF-OprN-mediated efflux in desB mutant, resulting in the decrease of MvfR binding to pqsA-E promoter and the reduction of 4-hydroxy-2-alkylquinolines (HAQs) synthesis. Overexpression of mexEF-oprN operon in desB mutant was phenotypically confirmed by observing significantly increased resistance to chloramphenicol. In conclusion, these results suggest that DesB plays a role in the inhibition of S. aureus growth by controlling HAQ synthesis. PMID:26230088

  3. Ansprache des Prsidenten anlsslich der Festveranstaltung

    E-print Network

    Falge, Eva

    Ansprache des Präsidenten anlässlich der Festveranstaltung zum 100jährigen Jubiläum des Fritz-Haber herzlich willkommen, 100 Jahre Fritz-Haber-Institut bzw. Kaiser-Wilhelm-Institut für physikalische Chemie heute einen Einblick geben in 100 Jahre Fritz-Haber-Institut. MAX-PLANCK-GESELLSCHAFT Rede des

  4. Descriptif des fonctions postules CORPS EMPLOIS

    E-print Network

    Pouyanne, Nicolas

    - Architecte des systèmes d'information - Chef de projet ou expert en développement et déploiement d - Architecte des systèmes d'information - Chef de projet ou expert en développement et déploiement d télécommunications - Ingénieur statisticien - Ingénieur en calcul scientifique IR - Architecte des systèmes d

  5. Direction de la documentation, des archives

    E-print Network

    Ghorbel, Amin

    le travail des groupes. Désormais au nombre de trois, les espaces- projets ont fait l'objet de plus Bibliothèque #12;5 Le succès des espaces-projets de la Bibliothèque Pour toujours mieux répondre aux attentes des élèves, une nouvelle salle de travail, la salle Jean Rouch, a été ouverte en septembre 2014 au

  6. Emmanuel Frenod Professeur des Universites -Mathematiques Appliquees

    E-print Network

    Frénod, Emmanuel

    Emmanuel Fr´enod Professeur des Universit´es - Math´ematiques Appliqu´ees Professor - Applied, ´equations cin´etiques, homog´en´eisation, m´ethodes math´ematiques de mod´elisation, analyse num´erique, calcul scientifique, Lo- giciels encapsulant des math´ematiques, mod´elisation des environnements

  7. Liquid ventilation.

    PubMed

    Sarkar, Suman; Paswan, Anil; Prakas, S

    2014-01-01

    Human have lungs to breathe air and they have no gills to breath liquids like fish. When the surface tension at the air-liquid interface of the lung increases as in acute lung injury, scientists started to think about filling the lung with fluid instead of air to reduce the surface tension and facilitate ventilation. Liquid ventilation (LV) is a technique of mechanical ventilation in which the lungs are insufflated with an oxygenated perfluorochemical liquid rather than an oxygen-containing gas mixture. The use of perfluorochemicals, rather than nitrogen as the inert carrier of oxygen and carbon dioxide offers a number of advantages for the treatment of acute lung injury. In addition, there are non-respiratory applications with expanding potential including pulmonary drug delivery and radiographic imaging. It is well-known that respiratory diseases are one of the most common causes of morbidity and mortality in intensive care unit. During the past few years several new modalities of treatment have been introduced. One of them and probably the most fascinating, is of LV. Partial LV, on which much of the existing research has concentrated, requires partial filling of lungs with perfluorocarbons (PFC's) and ventilation with gas tidal volumes using conventional mechanical ventilators. Various physico-chemical properties of PFC's make them the ideal media. It results in a dramatic improvement in lung compliance and oxygenation and decline in mean airway pressure and oxygen requirements. No long-term side-effect reported. PMID:25886321

  8. Infections fongiques des brûlé : revue

    PubMed Central

    Arnould, JF.; Le Floch, R.

    2015-01-01

    Summary Les infections fongiques locales ou générales sont souvent d’une extrême gravité chez les brûlés. Les brûlés combinent de nombreux facteurs de risque à une immunodépression induite par la brûlure. Les infections de plaies sont le fait des genres Candida, Aspergillus et des agents de mucormycoses. Ces deux derniers cas sont à l’origine de lésions particulièrement sévères. Leur diagnostic repose sur la biopsie cutanée avec examens mycologique et anatomopathologique. Le traitement est essentiellement chirurgical, associé à une antibiothérapie adaptée. Les septicémies sont le fait de levures, essentiellement du genre Candida. Le diagnostic en est difficile dans le contexte des brûlés et repose souvent sur une forte suspicion clinique. Leur traitement repose sur les échinocandines et plus secondairement sur le fluconazole. PMID:26668558

  9. Classification of 4 DES supernovae by OzDES

    NASA Astrophysics Data System (ADS)

    Glazebrook, K.; Amon, A.; Lidman, C.; Martini, P.; Tucker, B. E.; Yuan, F.; Aldering, G.; Kim, A. G.; Thomas, R. C.; Barbary, K.; Bloom, J. S.; Goldstein, D.; Nugent, P.; Perlmutter, S.; Foley, R. J.; Pan, Y.-C.; Casas, R.; Castander, F. J.; Desai, S.; Paech, K.; Smith, R. C.; Schubnell, M.; Kessler, R.; Lasker, J.; Scolnic, D.; Brout, D. J.; Gladney, L.; Sako, M.; Wolf, R. C.; Brown, P. J.; Krisciunas, K.; Suntzeff, N.; Nichol, R.; Papadopoulos, A.; Childress, M.; D'Andrea, C.; Smith, M.; Sullivan, M.; Maartens, R.; Gupta, R.; Kovacs, E.; Kuhlmann, S.; Spinka, H.; Ahn, E.; Finley, D. A.; Frieman, J.; Marriner, J.; Wester, W.

    2015-12-01

    We report new spectroscopic classifications by OzDES of supernovae discovered by the Dark Energy Survey (ATEL #4668). The spectra (370-885nm) were obtained with the AAOmega Spectrograph (Saunders et al. 2004, SPIE, 5492, 389) and the 2dF fibre positioner at the Anglo-Australian Telescope (AAT).

  10. Classification of 15 DES supernovae by OzDES

    NASA Astrophysics Data System (ADS)

    Yuan, F.; Tucker, B. E.; Lidman, C.; Martini, P.; Gshwend, Julia; Moller, A.; Zhang, B.; Smith, R. C.; Schubnell, M.; Kessler, R.; Lasker, J.; Scolnic, D.; Brout, D. J.; Gladney, L.; Sako, M.; Wolf, R. C.; Brown, P. J.; Krisciunas, K.; Suntzeff, N.; Nichol, R.; Papadopoulos, A.; Childress, M.; D'Andrea, C.; Smith, M.; Sullivan, M.; Maartens, R.; Gupta, R.; Kovacs, E.; Kuhlmann, S.; Spinka, H.; Ahn, E.; Finley, D. A.; Frieman, J.; Marriner, J.; Wester, W.; Aldering, G.; Kim, A. G.; Thomas, R. C.; Barbary, K.; Bloom, J. S.; Goldstein, D.; Nugent, P.; Perlmutter, S.; Foley, R. J.; Pan, Y.-C.; Casas, R.; Castander, F. J.; Desai, S.; Paech, K.

    2015-12-01

    We report new spectroscopic classifications by OzDES of supernovae discovered by the Dark Energy Survey (ATEL #4668). The spectra (370-885nm) were obtained with the AAOmega Spectrograph (Saunders et al. 2004, SPIE, 5492, 389) and the 2dF fibre positioner at the Anglo-Australian Telescope (AAT).

  11. Classification of 20 DES Supernova with OzDES

    NASA Astrophysics Data System (ADS)

    Davis, T. M.; Kim, A. G.; Macualay, E.; Lidman, C.; Sharp, R.; Tucker, B. E.; Yuan, F.; Zhang, B.; Lewis, G. F.; Sommer, N. E.; Martini, P.; Mould, J.; Ahn, E.; Finley, D. A.; Frieman, J.; Marriner, J.; Wester, W.; Aldering, G.; Thomas, R. C.; Barbary, K.; Bloom, J. S.; Goldstein, D.; Nugent, P.; Perlmutter, S.; Foley, R. J.; Pan, Y.-C.; Casas, R.; Castander, F. J.; Desai, S.; Paech, K.; Smith, R. C.; Schubnell, M.; Kessler, R.; Lasker, J.; Scolnic, D.; Brout, D. J.; Gladney, L.; Sako, M.; Wolf, R. C.; Brown, P. J.; Krisciunas, K.; Suntzeff, N.; Nichol, R.; Papadopoulos, A.; Childress, M.; D'Andrea, C.; Smith, M.; Sullivan, M.; Maartens, R.; Gupta, R.; Kovacs, E.; Kuhlmann, S.; Spinka, H.

    2015-12-01

    We report new spectroscopic classifications by OzDES of supernovae discovered by the Dark Energy Survey (ATEL #4668). The spectra (370-885nm) were obtained with the AAOmega Spectrograph (Saunders et al. 2004, SPIE, 5492, 389) and the 2dF fibre positioner at the Anglo-Australian Telescope (AAT).

  12. Classification of 14 DES Supernova with OzDES

    NASA Astrophysics Data System (ADS)

    Tucker, B. E.; Sharp, R.; Yuan, F.; Zhang, B.; Lidman, C.; Davis, T. M.; Hinton, S.; Mould, J.; Smith, R. C.; Schubnell, M.; Kessler, R.; Scolnic, D.; Covarrubias, R. A.; Brout, D. J.; Fischer, J. A.; Gladney, L.; March, M.; Sako, M.; Wolf, R. C.; Brown, P. J.; Krisciunas, K.; Suntzeff, N.; Nichol, R.; Papadopoulos, A.; D'Andrea, C.; Smith, M.; Sullivan, M.; Childress, M.; Maartens, R.; Gupta, R.; Kovacs, E.; Kuhlmann, S.; Spinka, H.; Ahn, E.; Finley, D. A.; Frieman, J.; Marriner, J.; Wester, W.; Aldering, G.; Kim, A. G.; Thomas, R. C.; Barbary, K.; Bloom, J. S.; Goldstein, D.; Nugent, P.; Perlmutter, S.; Foley, R. J.; Castander, F. J.; Desai, S.; Paech, K.

    2015-10-01

    We report new spectroscopic classifications by OzDES of supernovae discovered by the Dark Energy Survey. The spectra (370-885nm) were obtained with the AAOmega Spectrograph (Saunders et al. 2004, SPIE, 5492, 389) and the 2dF fibre positioner at the Anglo-Australian Telescope (AAT).

  13. Classification of 6 DES Supernova with OzDES

    NASA Astrophysics Data System (ADS)

    Lewis, G. F.; Mould, J.; Lidman, C.; Tucker, B. E.; Sharp, R.; Yuan, F.; Martini, P.; Kessler, R.; Scolnic, D.; Covarrubias, R. A.; Brout, D. J.; Fischer, J. A.; Gladney, L.; March, M.; Sako, M.; Wolf, R. C.; Brown, P. J.; Krisciunas, K.; Suntzeff, N.; Nichol, R.; Papadopoulos, A.; D'Andrea, C.; Smith, M.; Sullivan, M.; Childress, M.; Maartens, R.; Gupta, R.; Kovacs, E.; Kuhlmann, S.; Spinka, H.; Ahn, E.; Finley, D. A.; Frieman, J.; Marriner, J.; Wester, W.; Aldering, G.; Kim, A. G.; Thomas, R. C.; Barbary, K.; Bloom, J. S.; Goldstein, D.; Nugent, P.; Perlmutter, S.; Foley, R. J.; Casas, R.; Castander, F. J.; Desai, S.; Paech, K.; Smith, R. C.; Schubnell, M.

    2015-10-01

    We report new spectroscopic classifications by OzDES of supernovae discovered by the Dark Energy Survey (ATEL #4668). The spectra (370-885nm) were obtained with the AAOmega Spectrograph (Saunders et al. 2004, SPIE, 5492, 389) and the 2dF fibre positioner at the Anglo-Australian Telescope (AAT).

  14. Paternité des articles et intérêts concurrents : une analyse des recommandations aux auteurs des journaux traitant de pratique pharmaceutique

    PubMed Central

    Courbon, Ève; Tanguay, Cynthia; Lebel, Denis; Bussières, Jean-François

    2014-01-01

    RÉSUMÉ Contexte : La présence d’auteurs honorifiques et fantômes ainsi que les intérêts concurrents représentent des difficultés bien documentées, liées à la publication d’articles scientifiques. Il existe des lignes directrices encadrant la rédaction et la publication de manuscrits scientifiques, notamment celles de l’International Committee of Medical Journal Editors (ICMJE). Objectifs : L’objectif principal de cette étude descriptive et transversale visait à recenser les instructions portant sur la paternité des articles et les intérêts concurrents provenant des recommandations aux auteurs des journaux traitant de pratique pharmaceutique. L’objectif secondaire visait à déterminer des mesures correctrices pour une paternité des articles plus transparente. Méthode : La recherche a débuté par l’identification des journaux traitant de pratique pharmaceutique. La consultation des instructions aux auteurs des journaux a permis ensuite de recenser les recommandations destinées à éviter les problèmes de paternité des articles et d’intérêts concurrents. Finalement, les membres de l’équipe de recherche se sont consultés afin de définir des mesures correctrices possibles à l’intention des chercheurs. Résultats : Des 232 journaux traitant de pharmacie, 33 ont été définis comme traitant de pratique pharmaceutique. Un total de 24 (73 %) journaux mentionnaient suivre la politique de l’ICMJE, 14 (42 %) demandaient aux auteurs de remplir un formulaire de déclaration d’intérêts concurrents au moment de la soumission de l’article, 17 (52 %) présentaient une définition de la qualité d’auteur et 5 (15 %) demandaient de détailler les contributions de chaque auteur. Une grille de 40 critères a été élaborée pour définir l’attribution du statut d’auteur. Conclusion : Moins de la moitié des journaux demandait aux auteurs de transmettre un formulaire de déclaration des intérêts concurrents au moment de la soumission d’un article et seulement la moitié des journaux avait donné une définition de la qualité d’auteur. La publication scientifique de travaux sur les pratiques pharmaceutiques n’est pas à l’abri des manques de transparence liés à la publication. L’utilisation d’une grille décrivant la contribution de chaque auteur et la publication en ligne des travaux peuvent contribuer à limiter ces risques. PMID:24970938

  15. Video-microscopic observation of ionic liquid/alcohol interface and the corresponding molecular simulation study

    NASA Astrophysics Data System (ADS)

    Zhu, Peixi

    This research is aimed at studying the ionic liquid/n-pentanol interface via video-microscopy and molecular dynamic simulations. Understanding the interfacial phenomena and interfacial transport between ionic liquids and other liquids is of interest to the development and application of ionic liquids in a number of areas. One such area is the biphasic hydroformylation of alkenes to obtain alcohol and aldehyde, in which case ionic liquid is the reaction medium where a catalyst resides. The dissolution of an ionic liquid into an alcohol was studied by microscopically observing and measuring the shrinking of a micropipette-produced droplet in real time. Although microscopic investigation of droplet dissolution has been studied before, no attempt had been made to measure the diffusion coefficient D of the droplet species in the surrounding medium. A key finding of this work is that the Epstein-Plesset mathematical model, which describes the dissolution of a droplet/bubble in another fluid medium, can be used to measure D. Other experimental studies of the ionic liquid/alcohol system include electrical conductivity and UV-visible spectroscopy measurements of solutions of 1-hexyl-3-methylimidazolium tetrafluoroborate in n-pentanol. Those experiments were done in order to understand the molecular state of the particular ionic liquid in n-pentanol, as well as obtaining the dissociation constant K of such weak electrolyte solution. The experimental results provide an entry to the assessment of ionic liquid interaction with n-pentanol at molecular scale. Subsequently, molecular dynamics simulation was implemented for the investigation of such interaction. The computation started with simulation of the bulk phase of 1-butyl-3-methylimidazolium tetrafluoroborate, an affine ionic liquid on which molecular simulations had already been reported. A generalized probability based on Fuoss approximation for the closest ion to a distinguished countercharge ion was developed. In addition to 1-butyl-3-methylimidazolium tetrafluoroborate, the generalization was tested also on tetraethyl ammonium tetrafluoroborate in propylene carbonate from low to high concentrations, and on the corresponding primitive model. Such generalization helps us understand paring of ions in electrolyte solution, especially for elevated concentrations. Two cases of 1-hexyl-3-methylimidazolium tetrafluoroborate ionic liquid/n-pentanol system were studied, which are (i) liquid-liquid interface; and (ii) solution of the former in the latter. Computation of biphasic interface revealed interaction at the liquid-liquid junction, e.g., the transport of molecules from one phase to another, and lead to evaluation of diffusion coefficient that has good agreement with experimental measurement. The simulation of dilute electrolyte solution, i.e., an ionic liquid pair in n-pentanol, gives free energy change as a function of ion separation distance. The dissociation constant K was evaluated and found to be closed to experimental value that was obtained from solution conductivity measurement. The investigation of ion dynamics, especially the memory function transformed from velocity autocorrelation function, lead to the finding of dielectric friction in the system. Furthermore, precise evaluation of D gives satisfied agreement with experimental measurement from micropipette technique.

  16. Transport quantique dans des nanostructures

    NASA Astrophysics Data System (ADS)

    Naud, C.

    2002-09-01

    Quantum transport in nanostructures This work is devoted to the design, fabrication and magnetotransport investigations of mesoscopic devices. The sample are obtain by e-beam lithography and the measurements are performed at low temperature in a dilution refrigerator in the presence of a magnetic field. We have used MBE grown AlGaAs/GaAs heterojonctions as starting material to fabricate a bipartite tiling of rhombus called mathcal{T}3 lattice. We observe for the first time large amplitude h/e oscillations in this network as compared to the one measured in square lattices of similar size. These oscillations are the signature of a recently predited localization phenomenon induced by Aharonov-Bohm interferences on this peculiar topology. For particular values of the magnetic field the propagation of the electron wave function is bounded in a small number of cells, called Aharonov-Bohm cages. More strikingly, at high magnetic field, h/2e oscillations appear whose amplitude can be much higher than the fundamental period. Their temperature dependence is similar to that of the h/e signal. These observations withdraw a simple interpretation in terms of harmonics generation. The origin of this phenomenon is still unclear and needs more investigations. The influence electrical width of the wire defining the network and so the rule of the number of channels can be studied using a gate deposited over the lattice. In particular we have measured the amplitude dependence of the h/e and h/2e signal versus the gate voltage. Ce travail est consacré à la réalisation d'échantillons mésoscopiques à partir de la lithographie électronique ainsi qu'à leur caractérisation à très basse température en magnétotransport. Nous avons pour cela exploité le gaz bidimensionnel d'électrons situé à l'interface d'une hétérojonction AlGaAs/GaAs pour réaliser un réseau de boucle d'une géométrie particulière baptisée la géométrie mathcal{T}3. Nous avons observé sur cette structure des oscillations de conductance en fonction du flux du champ magnétique de période h/e dont l'amplitude est beaucoup plus importante que celle mesurée sur un réseau carré de même dimension. Cette différence constitue une signature d'un effet de localisation induit par le champ magnétique sur la topologie mathcal{T}3. Pour des valeurs spécifiques du champ magnétique, du fait des interférences destructives Aharonov-Bohm, la propagation des fonctions d'ondes est limitée à un ensemble fini de cellule du réseau appelé cage. De la dépendance en température des oscillations de période h/e mesurées sur le réseau mathcal{T}3 nous avons tiré une longueur caractéristique qui peut être rattachée au périmètre des cages. Un phénomène inattendu fut l'observation, pour des champs magnétiques plus importants, d'un doublement de fréquence des oscillations. Ces oscillations de période h/2e pouvant avoir une amplitude supérieure aux oscillations de période h/e, une interprétation en terme d'harmonique n'est pas possible. Enfin, l'influence de la largeur électrique des fils constituant le réseau et donc celle du nombre de canaux par brin a été étudiée en réalisant des grilles électrostatique. Les variations de l'amplitude des signaux en h/e et h/2e en fonction de la tension de grille ont été mesurés.

  17. Liquid electrode

    DOEpatents

    Ekechukwu, Amy A. (Augusta, GA)

    1994-01-01

    A dropping electrolyte electrode for use in electrochemical analysis of non-polar sample solutions, such as benzene or cyclohexane. The liquid electrode, preferably an aqueous salt solution immiscible in the sample solution, is introduced into the solution in dropwise fashion from a capillary. The electrolyte is introduced at a known rate, thus, the droplets each have the same volume and surface area. The electrode is used in making standard electrochemical measurements in order to determine properties of non-polar sample solutions.

  18. Evaluation of ligand effects in the modified cobalt hydroformylation of 1-octene. Crystal structures of [Co(L)(CO)3]2 (L = PA-C5, PCy3 and PCyp3).

    PubMed

    Bungu, Peter N; Otto, Stefanus

    2011-09-28

    A series of phosphine ligands with different electronic and steric properties were evaluated at fully modified conditions in cobalt catalysed hydroformylation of 1-octene. The steric demand of the ligands was based on the Tolman cone angle model covering a range of 132-175°. The electron donating ability was evaluated through the first order Se-P coupling constants as determined from the corresponding phosphine selenides covering a range of 672-752 Hz. Crystal structures of three phosphine modified cobalt dimers, [Co(CO)(3)(L)](2) (L = PA-C(5), PCy(3) and PCyp(3) with PA-C(5) = 1,3,5,7-tetramethyl-8-pentyl-2,4,6-trioxa-8-phosphatricyclo[3.3.1.1(3,7)]decane), are reported. The Phoban and Lim ligands (Phoban = mixture of 9-phosphabicyclo[3.3.1 and 4.2.1]nonane, Lim = 4,8-dimethyl-2-phosphabicyclo[3.3.1]nonane) resulted in systems about twice as active as most of the other ligands investigated, these ligands have a high Lewis basicity with (1)J(Se-P) values from 684-687 Hz. The linearity of the alcohol product in general decreased for the less electron donating ligands while no clear relationship was evident as a function of steric size. The parallel competing hydrogenation of 1-octene to octane varied from 9-15% for a cone angle range of 132-172°, but a sharp increase of up to 40% was observed for PA-C(5), PCy(3) and PCyp(3), all with cone angles > 169°. The catalytic behaviour provides evidence that is contrary to the dissociative substitution of CO by an alkene as the rate limiting step in all cases. For large symmetrical ligands, such as PA-C(5), PCy(3) and PCyp(3) the rate limiting step may move within the catalytic cycle and may now be situated at the carbonylation step where the chemoselectivity is also determined. The lack of clear correlation between the steric and electronic effect of the ligands and all catalytic parameters may serve as additional proof that the same system, especially in terms of the rate determining step, is not operative in all cases. The Phoban and Lim systems are superior with the highest reactivity and lowest alkene loss through hydrogenation. The unsymmetrical nature of the Phoban and Lim ligands may provide flexibility to adopt geometries inducing both high and low steric crowding, which may be a reason for its beneficial catalytic properties. PMID:21829832

  19. hors les murs des plantes

    E-print Network

    hors les murs au jardin des plantes 16 oct./ 201523 nov. mnhn.fr -- fiac.com 57 rue Cuvier -- Paris Georges-Philippe et Nathalie Vallois, Paris 5 - Lara Almarcegui Rocks of Spitsbergen, 2014, Présentée par 11 - Virginie Yassef L'objet du doute, 2013 Présentée par la Galerie Georges-Philippe et Nathalie

  20. DIRECTEUR DU CENTRE DES HUMANITS

    E-print Network

    Fiore, Marco

    activité profes- sionnelle. Les cours de connaissance de l'entreprise et de management visent cette transversale de cinquième année consacrée à l'innovation et à la créativité. Il est impliqué dans le projet d campus, l'INSA Lyon propose un véri- table environnement où la créativité artistique et culturelle des

  1. Deuxi eme partie Structure des ^

    E-print Network

    Clouard, Valerie

    and depth of frozen magma chambers under atolls and islands of French Polynesia using detailed gravity des ^ les et atolls de Polyn esie francaise qui a donn e lieu #12;a une publication dans le Journal under atolls and islands of French Polynesia using detailed gravity studies" R esum e De nouvelles

  2. In situ high pressure NMR studies of Co{sub 2}(CO){sub 6}[P(p-CF{sub 3}C{sub 6}H{sub 4}){sub 3}]{sub 2} in supercritical carbon dioxide : ligand substitution, hydrogenation, and hydroformylation reactions.

    SciTech Connect

    Chen, M. J.; Klingler, R. J.; Rathke, J. W.; Kramarz, K. W.; Chemical Engineering; Sunoco Chemicals

    2004-05-24

    The dimeric cobalt complex Co{sub 2}(CO){sub 6}[P(p-CF{sub 3}C{sub 6}H{sub 4}){sub 3}]{sub 2} (1) reacts reversibly with hydrogen to produce HCo(CO){sub 3}[P(p-CF{sub 3}C{sub 6}H{sub 4}){sub 3}] (4). The carbonyl and the phosphine ligands of both 1 and 4 are very labile. Compound 1 reacts with CO to give Co{sub 2}(CO){sub 7}[P(p-CF{sub 3}C{sub 6}H{sub 4}){sub 3}] (2), and compound 4 reacts with CO and P(p-CF{sub 3}C{sub 6}H{sub 4}){sub 3} (L) to give HCo(CO){sub 4} (5) and HCo(CO){sub 2}[P(p-CF{sub 3}C{sub 6}H{sub 4}){sub 3}]{sub 2} (6), respectively. The {sup 31}P NMR studies show that, in the presence of 1, the line width of the {sup 31}P resonance of L is temperature dependent, and at constant temperature, its broadening is proportional to the square root of the concentration of 1. This broadening is attributed to its exchange reaction with the mononuclear cobalt radical (CO){sub 3}LCo{sup {sm_bullet}} (3), which is generated by the homolysis of 1. Compound 1 catalyzes the hydroformylation of olefins in supercritical carbon dioxide. In contrast to the unsubstituted Co{sub 2}(CO){sub 8}, the phosphine-modified catalyst system is stable under low CO pressures and the hydroformylation reactions can be carried out at low pressures. In situ monitoring of {sup 31}P and {sup 59}Co NMR spectra of the solution shows that the phosphine-containing hydrido cobalt complexes 4 and 6 are the only hydrido cobalt complexes present in detectable concentrations in 1-catalyzed hydroformylation reactions; nevertheless, the possibility that the observed activity for 1 comes primarily from the more active HCo(CO){sub 4}, present in concentrations below detectable limits, has not been rigorously excluded.

  3. Liquid electrode

    DOEpatents

    Ekechukwu, A.A.

    1994-07-05

    A dropping electrolyte electrode is described for use in electrochemical analysis of non-polar sample solutions, such as benzene or cyclohexane. The liquid electrode, preferably an aqueous salt solution immiscible in the sample solution, is introduced into the solution in dropwise fashion from a capillary. The electrolyte is introduced at a known rate, thus, the droplets each have the same volume and surface area. The electrode is used in making standard electrochemical measurements in order to determine properties of non-polar sample solutions. 2 figures.

  4. Classification of DES15S2myz and DES15S2mwz by GTC

    NASA Astrophysics Data System (ADS)

    Casas, R.; Castander, F. J.; Desai, S.; Paech, K.; Smith, R. C.; Schubnell, M.; Kessler, R.; Lasker, J.; Scolnic, D.; Brout, D. J.; Gladney, L.; Sako, M.; Wolf, R. C.; Brown, P. J.; Krisciunas, K.; Suntzeff, N.; Nichol, R.; Papadopoulos, A.; Childress, M.; D'Andrea, C.; Smith, M.; Sullivan, M.; Maartens, R.; Gupta, R.; Kovacs, E.; Kuhlmann, S.; Spinka, H.; Ahn, E.; Finley, D. A.; Frieman, J.; Marriner, J.; Wester, W.; Aldering, G.; Kim, A. G.; Thomas, R. C.; Barbary, K.; Bloom, J. S.; Goldstein, D.; Nugent, P.; Perlmutter, S.; Foley, R. J.; Pan, Y.-C.

    2015-12-01

    We report optical spectroscopy of DES15S2myz and DES15S2mwz discovered by the Dark Energy Survey (ATel #4668). The spectra (495-920nm) were obtained using OSIRIS on the Gran Telescopio CANARIAS (GTC).

  5. Traitement Automatique des Langues Naturelles, Marseille, 2014 Grammaire rcursive non linaire pour les langues des signes

    E-print Network

    linguistique. Par exemple, l'expression de relations spa les langues des signes, rendant compte de leurs particularités linguistiques. Comparable aux'analyse des liens entre formes produites/observées et fonctions linguistiques au sens large, on observe un

  6. Evaluation des connaissances des parents sur les bronchiolites aiguës

    PubMed Central

    Gueddari, Widad; Tazi, Abderrahmane; Ouardi, Amine; Nani, Samira; Zineddine, Abdelhadi

    2014-01-01

    Les infections respiratoires (IR) constituent la deuxième cause de mortalité infantile au Maroc, dû en partie à l'absence d'information et de sensibilisation. Le but de ce travail était d’évaluer les connaissances des parents sur la bronchiolite aiguë, infection respiratoire très fréquente. Nous avons réalisé une enquête basée sur un questionnaire, auprès de parents de nourrissons consultants pour toux, avec ou sans gêne respiratoire. 180 parents ont été inclus dans l’étude. Les parents pensaient que l'infection respiratoire était secondaire au climat froid (96%); seuls 4% ont évoqué une origine infectieuse. Aucun des parents ne savait que le lavage des mains était un moyen de prévention de la transmission. Les parents ont majoritairement répondu que la kinésithérapie respiratoire ne servait à rien (65%), et qu'elle était nocive (24.5%). Ce manque de connaissances fondamentales en matière d'IR et de bronchiolite en particulier, devrait inciter à entreprendre un programme de sensibilisation PMID:25328606

  7. Caractérisation des convertisseurs matriciels : II. Synthèse des fonctions de connexion

    NASA Astrophysics Data System (ADS)

    François, B.; Cambronne, J. P.; Hautier, J. P.

    1996-05-01

    Knowing the wished conversion levels (-1,0,1) of a power converter, this paper describes a particular method for setting the corresponding states of switches into the matrix converter. In a first step, a mathematical analysis establishes the relations linking the states of switches with the conversion functions. Afterwards, the presented method gives the inverse relations which constitute the sequential part of the converter control. The turn-on and the turn-off sequences are designed by considering the on-line wished level conversions. This general method enhances the idea that a converter functionnality must be defined by its structure and its control. Cet article propose une méthode originale pour définir la séquence de commande d'un convertisseur à partir de la fonction de conversion globalement souhaitée. Les auteurs procèdent d'abord à une analyse mathématique précise des relations qui existent entre les états des interrupteurs et les fonctions de conversion obtenues. À partir de cette analyse, la méthode developpée permet d'établir systématiquement les relations inverses qui constituent alors le module séquentiel de la commande rapprochée du convertisseur. Les ordres d'ouverture et de fermeture des interrupteurs sont élaborés en considérant à tout instant les niveaux de conversion souhaités pour les grandeurs électriques. Cette méthode générale renforce l'idée que la fonction remplie par un convertisseur moderne doit être définie à la fois par sa structure et sa commande.

  8. Photonique des Morphos

    NASA Astrophysics Data System (ADS)

    Bertone, Gianfranco

    2010-01-01

    Part I. DM in Cosmology: 1. Particle dark matter G. Bertone and J. Silk; 2. Simulations of CDM haloes B. Moore and J. Diemand; 3. MW substructures J. Bullock, M. Kaplinghat and L. Strigari; 4. Gravitational lensing and dark matter Y. Mellier; 5. Dark matter at the centers of galaxies D. Merritt; 6. Modified gravity as an alternative to DM J. Bekenstein; Part II. Candidates: 7. DM production mechanisms G. Gelmini and P. Gondolo; 8. Supersymmetric DM candidates J. Ellis and K. Olive; 9. DM at the EW scale: non-SUSY candidates G. Servant; 10. Non-WIMP candidates J. L. Feng; 11. Axions P. Sikivie; 12. Sterile neutrinos M. Shaposhnikov; Part III. Colliders Searches: 13. SUSY searches at the LHC T. Plehn and G. Polesello; 14. SUSY DM at colliders M. Battaglia and M. E. Peskin; 15. Extra dimensions at the LHC K. Kong, K. Matchev and G. Servant; 16. SUSY tools F. Boudjema, J. Edsjö and P. Gondolo; Part IV. Direct Detection: 17. Direct detection of WIMPs D. G. Cerdeño and A. Green; 18. Annual modulation with NaI(Tl) R. Bernabei and P. Belli; 19. Particle DM and DAMA N. Fornengo; 20. Cryogenic detectors G. Gerbier and J. Gascon; 21. Liquid noble gases E. Aprile and L. Baudis; 22. Directional detectors N. Spooner; 23. Axion searches S. Asztalos; Part V. Indirect Detection and Astrophysical Constraints: 24. Gamma-rays L. Bergström and G. Bertone; 25. Neutrinos F. Halzen and D. Hooper; 26. Antimatter P. Salati, F. Donato and N. Fornengo; 27. Multi-wavelength S. Profumo and P. Ullio; 28. Dark matter and BBN K. Jedamzik and M. Pospelov; 29. Dark matter and stars G. Bertone; Appendix; References; Index.

  9. Direction des Ressources Humaines Contacts Bureau des concours Ple GPEEC / Bureau des Concours nicole.berkowitz@univ-amu.fr

    E-print Network

    Avignon et des Pays de Vaucluse, Université de

    (titulaires, non titulaires, contrats étudiants). Positionnement hiérarchique : sous l'autorité du responsable administratif. COMPETENCES REQUISES : Connaissances générales et intérêt pour la gestion des ressources humaines

  10. Les applications des faisceaux d'ions dans la physique des polymères

    NASA Astrophysics Data System (ADS)

    Ratier, B.; Moliton, A.; Lucas, B.; Guille, B.; Clamadieu, M.

    1998-06-01

    Experimental configurations of ions beams are illustrated by diagrams in the case of low energy implantation, Reactive Ion Beam Etching (RIBE), Ion Beam Assisted Deposition (IBAD) of molecular layers (or oligomers). Nous présentons les configurations expérimentales (illustrées par des schémas) de trois applications des faisceaux d'ions au traitement physique des polymères : dopage par implantation (cité pour mémoire), gravure par faisceaux d'ions réactifs (RIBE), dépôt des couches moléculaires (ou oligomères) assistés par faisceau (IBAD).

  11. M2 OASC : Fiche de stage Titre du stage : Apport d'une simulation haute rsolution pour la description des tourbillons en mer des

    E-print Network

    description des tourbillons en mer des Salomon Nom et statut du (des) responsable (s) de stage : Gourdeau Sujet du stage : La mer des Salomon située dans le Pacifique sud ouest est le lieu de transit des courants de bord ouest lors de leur traversée de la mer des Salomon sont soumis à des contraintes

  12. Partager : des technologies de pointe au service de la société

    ScienceCinema

    None

    2011-10-06

    Médecine, climatologie, métrologie et informatique, les techniques utilisées par le LHC trouvent déjà des répercussions dans d?autres domaines scientifiques. Utilisant des techniques inédites, la physique des particules en fait bénéficier la société toute entière.

  13. Werkzeuge der Informatik Grundlagen und Werkzeuge des WWW (Teil 1)

    E-print Network

    Zachmann, Gabriel

    . Müller, 2011 Geschichte des WWW · Anfänge des WWW Geschichte des Internet · 1980: Tim Berners-Lee (CERN) schreibt Programm "ENQUIRE", das es erlaubt, Knoten im Internet zu verlinken · 1989: Tim Berners-Lee: CERN

  14. Universit Paris XIII Mmoire d'Habilitation Diriger des Recherches

    E-print Network

    Poinsot, Laurent

    Université Paris XIII Mémoire d'Habilitation à Diriger des Recherches Spécialités : Mathématiques Mathématiques, EA 4535 Claude Carlet Professeur des Universités, Université Paris VIII Vincennes. Duchamp Professeur des Universités, Université Paris XIII, Rapporteur Laboratoire d'Informatique de Paris

  15. Devenir des diplms Promotion 2011-2012

    E-print Network

    Sart, Remi

    de l'enquête. 64,6% occupent des fonctions cadres. Le salaire net mensuel moyen est de 1726 . Photo(s):©JérômePALL�-UniversitéBlaisePascal leur diplôme. Concernant les Masters de l'Université Blaise Pascal, sur les 1136 diplômés de la des diplômés de Master de l'Université Blaise Pascal, toutes formations confondues. > > Sommaire des

  16. Etude des Seuils de Poursuite et de Dmodulation des Signaux Galileo pour

    E-print Network

    Dobigeon, Nicolas

    Etude des Seuils de Poursuite et de Démodulation des Signaux Galileo pour l'Aviation Civile Lieu'utilisation de Galileo par l'aviation civile. D'autre part, dans le cadre de discussions bilatérales entre les signaux GPS et Galileo, et, en particulier, afin de s'assurer que la co-existence des signaux GPS et

  17. Profil épidemio-clinique et radiologique des atteintes ostéo-articulaires des hémophiles à Madagascar

    PubMed Central

    Narindra, Lova Hasina Rajaonarison Ny Ony; Rabemanorintsoa, Feno Hasina; Randrianantenaina, Faralahy Ravelonarivo; Rakoto, Olivat Alson Aimée; Ahmad, Ahmad

    2014-01-01

    Introduction Déterminer le profil épidémio-clinique et radiologique des atteintes ostéo-articulaires des hémophiles malagasy. Méthodes Une étude prospective, descriptive portant sur 25 patients hémophiles venant de tout Madagascar a été réalisée. Des radiographies numérisées des genoux, des chevilles et des coudes en incidence de face et de profil ainsi qu'une échographie des hanches, des genoux, des chevilles et des coudes ont été réalisées chez ces patients. Le type et la sévérité de la maladie ainsi que l'aspect de la cavité articulaire, la synoviale, les noyaux épiphysaires et les surfaces articulaires ont été analysés. Résultats Soixante-huit pourcent des patients étaient hémophiles de type A et 32 % de type B. Quarante pourcent étaient classés sévères, 28 % modérés et 32 % mineurs. Les atteintes ostéo-articulaires ont été retrouvées chez 56 % des patients. Il n'existait pas de prédominance d'atteinte selon le type ni la sévérité de la maladie. Les plus jeunes étaient les plus atteints et l'articulation du genou et de la cheville étaient les plus touchées. Conclusion Les complications ostéo-articulaire de l'hémophilie sont graves et ne dépendent pas du type ni de la sévérité de l'affection. Elles touchent surtout les enfants d'âge scolaire. Le couple radiographie-échographie permet de diagnostiquer et de surveiller ces lésions. PMID:25870742

  18. Aide aux doctorants pour la participation des Aide aux doctorants pour la participation des colloques

    E-print Network

    Di Girolami, Cristina

    Aide aux doctorants pour la participation à des colloques Aide aux doctorants pour la participation à des colloques retour Formation doctorale Aide aux doctorants pour la participation à des colloques aide vient compléter les financements déjà prévus par les laboratoires et les Écoles doctorales pour

  19. Liquid foams of graphene

    E-print Network

    Alcazar Jorba, Daniel

    2012-01-01

    Liquid foams are dispersions of bubbles in a liquid. Bubbles are stabilized by foaming agents that position at the interface between the gas and the liquid. Most foaming agents, such as the commonly used sodium dodecylsulfate, ...

  20. Lacerations - liquid bandage

    MedlinePLUS

    Skin adhesives; Tissue adhesive ... the cut is minor, a liquid bandage (liquid adhesive) can be used on the cut to close ... bandage is quick and painless to apply. Skin adhesives, or liquid bandages, seal the cut closed after ...

  1. Liquid Crystal Devices.

    ERIC Educational Resources Information Center

    Bradshaw, Madeline J.

    1983-01-01

    The nature of liquid crystals and several important liquid crystal devices are described. Ideas for practical experiments to illustrate the properties of liquid crystals and their operation in devices are also described. (Author/JN)

  2. Liquid Crystal Inquiries.

    ERIC Educational Resources Information Center

    Marroum, Renata-Maria

    1996-01-01

    Discusses the properties and classification of liquid crystals. Presents a simple experiment that illustrates the structure of liquid crystals and the differences between the various phases liquid crystals can assume. (JRH)

  3. Relation entre les caractéristiques des table-bancs et les mesures anthropométriques des écoliers au Benin

    PubMed Central

    Falola, Stève Marjelin; Gouthon, Polycarpe; Falola, Jean-Marie; Fiogbe, Michel Armand; Nigan, Issiako Bio

    2014-01-01

    Introduction Le mobilier scolaire et la posture assise en classe sont souvent impliqués dans l'apparition des douleurs rachidiennes, influant de fait sur la qualité des tâches réalisées par les apprenants. Aucune étude n'a encore vérifié le degré d'adéquation entre les caractéristiques du mobilier et celles des écoliers au Bénin. L'objectif de cette étude transversale est donc de déterminer la relation entre les dimensions des table-bancs utilisées en classe et les mesures anthropométriques des écoliers au Bénin. Methods Elle a été réalisée avec un échantillon probabiliste de 678 écoliers, âgés de 4 à 17 ans. Les mesures anthropométriques des écoliers et les mensurations relatives aux longueurs, largeurs et hauteurs des table-bancs ont été mesurées, puis intégrées aux équations proposées dans la littérature. Les pourcentages des valeurs situées hors des limitesacceptables, dérivées de l'application des équations ont été calculés. Results La largeur et la hauteur des table-bancs utilisées par les écoliers étaient plus élevées (p < 0,05) que les valeurs de référence recommandées par les structures officielles de contrôle et de production des mobiliers scolaires au Bénin. Quel que soit le sexe, il y avait une inadéquation entre la largeur du banc et la longueur fesse-poplité, puis entre la hauteur de la table et la distance coude-bancdes écoliers. Conclusion Les résultats suggèrent de prendre en compte l’évolution des mesures anthropométriques des écoliers dans la confection des table-bancs, afin de promouvoir de bonnes postures assises en classe et de réduire le risque de troubles du rachis. PMID:25317232

  4. Le traitement familial des enfants et des adolescents anorexiques : Des lignes directrices pour le médecin communautaire

    PubMed Central

    Findlay, S; Pinzon, J; Taddeo, D; Katzman, DK

    2010-01-01

    L’anorexie mentale (AM) est une maladie grave qui met la vie en danger et qui fait généralement son apparition pendant l’adolescence. Les données probantes au sujet du traitement optimal de l’AM chez les enfants et les adolescents sont en croissance, mais il reste beaucoup à apprendre. Même si les démarches thérapeutiques actuelles varient au Canada et ailleurs, les données jusqu’à présent indiquent que le traitement familial (TF) est le plus efficace pour les enfants et les adolescents anorexiques. Un élément essentiel du modèle de TF, c’est que les parents sont investis de la responsabilité de rétablir la santé physique de leur enfant et de s’assurer de la reprise complète de son poids. Le médecin qui comprend les principes fondamentaux et la philosophie du TF peut mettre en place les éléments de cette intervention fondée sur des faits probants auprès des jeunes patients anorexiques et de leur famille.

  5. Le dialecte natal: analyse de l’opinion des intellectuels et des villageois de Lituanie

    E-print Network

    Ka?iuškien?, Genovait?

    2010-02-01

    dialecte natal: analyse de l’opinion des intellectuels et des villageois de Lituanie Genovait? ka?iuškien? Université de Šiauliai, Faculté des sciences humaines, P. Višinskio 38, LT – 76352 Šiauliai, geno@splius.lt ?lanek temelji na izsledkih...–165 — 139 — Le dialecte natal: analyse de l’opinion des intellectuels et des villageois de Lituanie Le lituanien comporte deux grands groupes dialectaux : celui de l’ouest, la Basse-Lituanie ou Samogites (žemaitija), et celui de l’est, la Haute...

  6. Using XML to encode TMA DES metadata

    PubMed Central

    Lyttleton, Oliver; Wright, Alexander; Treanor, Darren; Lewis, Paul

    2011-01-01

    Background: The Tissue Microarray Data Exchange Specification (TMA DES) is an XML specification for encoding TMA experiment data. While TMA DES data is encoded in XML, the files that describe its syntax, structure, and semantics are not. The DTD format is used to describe the syntax and structure of TMA DES, and the ISO 11179 format is used to define the semantics of TMA DES. However, XML Schema can be used in place of DTDs, and another XML encoded format, RDF, can be used in place of ISO 11179. Encoding all TMA DES data and metadata in XML would simplify the development and usage of programs which validate and parse TMA DES data. XML Schema has advantages over DTDs such as support for data types, and a more powerful means of specifying constraints on data values. An advantage of RDF encoded in XML over ISO 11179 is that XML defines rules for encoding data, whereas ISO 11179 does not. Materials and Methods: We created an XML Schema version of the TMA DES DTD. We wrote a program that converted ISO 11179 definitions to RDF encoded in XML, and used it to convert the TMA DES ISO 11179 definitions to RDF. Results: We validated a sample TMA DES XML file that was supplied with the publication that originally specified TMA DES using our XML Schema. We successfully validated the RDF produced by our ISO 11179 converter with the W3C RDF validation service. Conclusions: All TMA DES data could be encoded using XML, which simplifies its processing. XML Schema allows datatypes and valid value ranges to be specified for CDEs, which enables a wider range of error checking to be performed using XML Schemas than could be performed using DTDs. PMID:21969921

  7. The electromechanics of liquids electrowetting (EWOD) & liquid

    E-print Network

    Jones, Thomas B.

    experiment with cryogenic liquids Lumped parameter electromechanical model successfully predicts height-of-rise at the midpoint ... but NOT the details of meniscus profile. hcap hDEP V D cryogenic liquid: l, l g vapor phase cryogenic liquid: l, l w h = hcap+hDEP view thru electrodes profile does not depend on E #12;12 Pellat

  8. Bisamino(diphosphonite) with dangling olefin functionalities: synthesis, metal chemistry and catalytic utility of Rh(I) and Pd(II) complexes in hydroformylation and Suzuki-Miyaura reactions.

    PubMed

    Naik, Susmita; Kumaravel, Maruthai; Mague, Joel T; Balakrishna, Maravanji S

    2014-01-21

    Bisamino(diphosphonite), p-C6H4{N{P(OC6H4C3H5-o)2}2}2 (1), was prepared by reacting p-C6H4{N(PCl2)2}2 with four equivalents of o-allylphenol in 85% yield. Compound 1 on treatment with [M(CO)4(HNC5H10)2] (M = Mo or W) gave cis-[{M(CO)4}2{p-C6H4{N(P(OC6H4C3H5-o)2)2}2}] (2, M = Mo; 3, M = W). The reaction of 1 with [Fe(?(5)-C5H5)(CO)2]2 yielded the complex [{Fe(?(5)-C5H5)(?-CO)}2{p-C6H4{N(P(OC6H4C3H5-o)2)2}2}] (4). Treatment of 1 with Fe(CO)5 furnished a mononuclear complex, [{Fe(CO)3}2{p-C6H4{N{P(OC6H4C3H5-o)2}2}2}] (5). The ruthenium(II) complex, [{(?(6)-p-cymene)Ru(?-Cl)3RuCl}2{p-C6H4{N(P(OC6H4C3H5-o)2)2}2}] (6), was obtained on treatment of ligand 1 with [(?(6)-p-cymene)Ru(Cl)2]2. The reaction between 1 and [Rh(COD)Cl]2 (COD = 1,5-cyclooctadiene) in dichloromethane resulted in the formation of a dinuclear complex [{RhCl}2{p-C6H4{N(P(OC6H4C3H5-o)2)2}2}] (7), in which the allyl double bond of one of the phenoxy groups coordinates to the metal center. When ligand 1 was reacted with two equivalents of [Pd(COD)Cl2], a dinuclear complex [{PdCl2}2{p-C6H4{N(P(OC6H4C3H5-o)2)2}2}] (8) was obtained. With copper(I) halides, ligand 1 afforded tetranuclear complexes, [{(Cu(?-X)(NCCH3))2}2{p-C6H4{N(P(OC6H4C3H5-o)2)2}2}] (9, X = Cl; 10, X = Br; 11, X = I). Reaction of 1 with four equivalents of [AuCl(SMe2)] produced a tetranuclear complex, [(AuCl)4{p-C6H4{N{P(OC6H4C3H5-o)2}2}2}] (12). Complex 8 shows excellent catalytic activity in the Suzuki-Miyaura cross-coupling reaction under microwave conditions and complex 7 catalyzes hydroformylation of styrenes with good TONs. PMID:24165930

  9. Agénésie bilatérale des vésicules séminales et des canaux déférents

    PubMed Central

    Kassogué, Amadou; El Ammari, J. Eddine; Diarra, Alkadri; Amiroune, Driss; Ahsaini, Mustapha; Ouldim, Karim; Traoré, Zacharia; Sqalli, H. Nadia; Tizniti, Siham; Mellas, Soufiane; Tazi, M. Fadl; Khallouk, Abdelhak; El Fassi, M. Jamal; Farih, My Hassan

    2014-01-01

    Résumé L’absence de canaux déférents et de vésicules séminales est une cause très rare d’infertilité masculine qui pose des difficultés d’ordre diagnostique. De plus, son traitement est complexe. Dans le présent article, nous rapportons le cas d’un patient âgé de 43 ans qui a consulté pour infertilité primaire évoluant depuis 5 ans (un conseil génétique a été réalisé) et nous examinons les difficultés diagnostiques et thérapeutiques liées à cette forme particulière d’infertilité. PMID:25132895

  10. Dies academicus 2012 Bericht des Rektors

    E-print Network

    Zürich, Universität

    Dies academicus 2012 Bericht des Rektors Wie es bereits zur Tradition geworden ist, nehme ich Sie Glanzlichtern des vergangenen Jahres zählte. Zum ersten Mal organisierten die Universität Zürich und die ETH gemeinsam die Zürcher Wissenschaftstage und luden während eines ganzen Wochenendes zur Begegnung und zum

  11. DES Chapter 10 The Condensed Financial

    E-print Network

    Schubart, Christoph

    or Actual sheets. The spreadsheet automatically condenses the Comprehensive sheet into a format called theComprehensive sheet into a format called the Condensed sheet. See DES Chapter 10 and its Appendix (continued) DES (Gerichtsverfahren), casualty losses due to flood, fire, or tornado, and gains or l th ti i h t (Ablö ) f d btlosses

  12. Copernic: la piste des influences arabes

    NASA Astrophysics Data System (ADS)

    Khalatbari, A.; Bonnet-Bidaud, J. M.

    2004-10-01

    Copernic a-t-il connu le travail des astronomes du Moyen-Orient ? S'en est-il inspiré pour élaborer sa théorie de l'héliocentrisme ? C'est l'hypothèse avancée par certains historiens des sciences pour comprendre le génie de celui qui, le premier, a placé le Soleil au centre du monde. Enquête.

  13. JOSEPH LOUIS LAGRANGE, THORIE DES FONCTIONS ANALYTIQUES,

    E-print Network

    Fraser, Craig

    CHAPTER 19 JOSEPH LOUIS LAGRANGE, TH�ORIE DES FONCTIONS ANALYTIQUES, FIRST EDITION (1797) Craig G (§25). 1 INTRODUCTION At the end of the 18th century Joseph Louis Lagrange (1736­1813) published a book Elsevier B.V. All rights reserved. 258 #12;Chapter 19. Joseph Louis Lagrange, Théorie des fonctions

  14. Facult des sciences de l'agriculture

    E-print Network

    Laval, Université

    #12;Faculté des sciences de l'agriculture et de l'alimentation Rapport annuel des activités de'agriculture et de l'alimentation Vice-décanat à la recherche Madame, Monsieur, En 2007-2008, la Faculté de sciences de l'agriculture et de l'alimentation a connu une autre très bonne année quant au financement de

  15. Facult des sciences de l'agriculture

    E-print Network

    Laval, Université

    Faculté des sciences de l'agriculture et de l'alimentation Rapport annuel des activités de'agriculture et de l'alimentation Vice-décanat à la recherche Madame, Monsieur, C'est avec un plaisir renouvelé'agriculture et de l'alimentation (FSAA). Encore une fois, les chercheurs de la FSAA ont su démontrer une

  16. Quelques tendances actuelles en histoire des mathematiques.

    E-print Network

    Aubin, David

    Development, sous la dir. de Joseph W. Dauben et Christoph J. Scriba, Birkh¨auser, B^ale, 2002, p. 6. 3 Voir Catherine Goldstein, Jeremy Gray et Jim Ritter, dir., L'Europe math´ematique : histoire, mythes, identit´ematiques `a des ´epoques et dans des cultures diff´erentes. Dans un ouvrage r´ecent dirig´e par Joseph Dauben

  17. Gestion durable des ressources en agriculture

    E-print Network

    Sart, Remi

    Gestion durable des ressources en agriculture Mention : Agronomie Nature de la formation : Diplôme durable des ressources en agriculture UFR Sciences et Technologies PRÉSENTATION Objectifs La Licence diplôme sera donc un technicien spécialisé à l'interface entre l'agriculture et l

  18. Les implications du phénomène des médecins hospitaliers

    PubMed Central

    Lehmann, François; Brunelle, Yvon; Dawes, Martin; Boulé, Richard; Bergeron, Rénald

    2007-01-01

    RÉSUMÉ OBJECTIF Évaluer l’impact de 2 systèmes de soins hospitaliers par une revue de la littérature. QUALITÉ DES DONNÉES Il reste des zones nébuleuses car plusieurs des études sont opportunistes, signalant une expérience isolée ou de simples avant-après. Peu sont vraiment expérimentales et toutes ont été menées dans des milieux universitaires, limitant ainsi leur validité externe. MESSAGE PRINCIPAL Les données supportent l’utilisation de médecins hospitaliers qui consacrent un minimum de 2 mois par année à ce travail et qui sont alors à plein temps sur les étages. Les coûts sont plus souvent qu’autrement réduits et l’enseignement est amélioré. Point de repère important de la qualité des soins, la mortalité est égale dans les 2 systèmes de soins. CONCLUSION Certaines questions demeurent sans réponse dont le choix de la meilleure formation en vue de préparer les résidents au travail hospitalier et la façon de maintenir les compétences acquises. PMID:18077751

  19. Electrokinetics over liquid/liquid interfaces

    NASA Astrophysics Data System (ADS)

    Squires, Todd M.

    2011-11-01

    Since liquid-liquid interfaces flow in response to an applied stress, one might expect electrokinetic flows at liquid-liquid interfaces to be significantly higher than over liquid-solid interfaces. The earliest predictions for the electrophoretic mobility of charged mercury drops - distinct approaches by Frumkin and Levich (1946), and Booth (1951) - differed by O (a /?D) , where a is the radius of the drop and ?D is the Debye screening length. Seeking to reconcile this rather striking discrepancy, Levine (1973) showed double-layer polarization to be the key ingredient. Without a physical mechanism by which electrokinetic effects are enhanced, however, it is difficult to know how general the enhancement is - whether it holds only for liquid metal surfaces, or more generally, for all liquid/liquid surfaces. By considering a series of systems in which a planar metal strip is coated with either a liquid metal or liquid dielectric, we show that the central physical mechanism behind the enhancement predicted by Frumkin and Levich (1946) is the presence of an unmatched electrical stress upon the electrolyte-liquid interface, which establishes a Marangoni stress on the droplet surface and drives it into motion. The source of the unbalanced electrokinetic stress on a liquid metal surface is clear - metals represent equipotential surfaces, so no field exists to drive an equal and opposite force on the surface charge. This might suggest that liquid metals represent a unique system, since dielectric liquids can support finite electric fields, which might be expected to exert an electrical stress on the surface charge that balances the electric stress. We demonstrate, however, that electrical and osmotic stresses on relaxed double-layers internal to dielectric liquids precisely cancel, so that internal electrokinetic stresses generally vanish in closed, ideally polarizable liquids. The enhancement for liquid mercury drops can thus be expected quite generally over clean, ideally polarizable liquid drops. More broadly, the ability to reliably engineer liquid interfaces in microfluidic systems, then, may provide a path to significantly enhanced electrokinetic flows. Research done in collaboration with A. J. Pascall.

  20. Ionic Liquids Database- (ILThermo)

    National Institute of Standards and Technology Data Gateway

    SRD 147 Ionic Liquids Database- (ILThermo) (Web, free access)   IUPAC Ionic Liquids Database, ILThermo, is a free web research tool that allows users worldwide to access an up-to-date data collection from the publications on experimental investigations of thermodynamic, and transport properties of ionic liquids as well as binary and ternary mixtures containing ionic liquids.

  1. Liquid crystal polyester thermosets

    SciTech Connect

    Benicewicz, B.C.; Hoyt, A.E.

    1990-01-01

    The present invention relates to the field of curable liquid crystal polyester monomers and to thermoset liquid crystalline polyester compositions prepared therefrom. It is an object of this invention to provide curable liquid crystalline polyester materials. Another object of this invention is to provide a process of preparing curable liquid crystal polyester monomers. Yet another object of this invention is to provide liquid crystalline blends of polyester materials. It is a further object of this invention to provide thermoset liquid crystalline polyester compositions. It is a still further object of this invention to provide thermoset liquid crystalline polyester compositions having a high heat resistance. 1 fig.

  2. Liquid crystal polyester thermosets

    SciTech Connect

    Benicewicz, B.C.; Hoyt, A.E.

    1990-12-31

    The present invention relates to the field of curable liquid crystal polyester monomers and to thermoset liquid crystalline polyester compositions prepared therefrom. It is an object of this invention to provide curable liquid crystalline polyester materials. Another object of this invention is to provide a process of preparing curable liquid crystal polyester monomers. Yet another object of this invention is to provide liquid crystalline blends of polyester materials. It is a further object of this invention to provide thermoset liquid crystalline polyester compositions. It is a still further object of this invention to provide thermoset liquid crystalline polyester compositions having a high heat resistance. 1 fig.

  3. Le diagnostic anténatal de la trisomie 21 par l'hybridation in situ en fluorescence (FISH): à propos des premiers tests réalisés au Maroc

    PubMed Central

    Lamzouri, Afaf; Natiq, Abdelhafid; Tajir, Mariam; Sendid, Mohamed; Sefiani, Abdelaziz

    2012-01-01

    Introduction Le but de cette étude était de présenter les premiers résultats de diagnostic anténatal de la trisomie 21 par la technique d'hybridation in situ en fluorescence (FISH) au Maroc et discuter son intérêt dans le diagnostic rapide de cette aneuploïdie. Méthodes Ce travail a été réalisé chez 23 femmes avec des grossesses à haut risque de trisomie 21. La moyenne d’âge des gestantes étaient de 37,43 ans avec des extrêmes de 21 et 43 ans. Toutes étaient musulmanes mariées, mariage légitimé par la Charia, dont trois mariages consanguins, sauf une originaire de la République Démocratique du Congo qui était chrétienne et concubine. La majorité des femmes étaient fonctionnaires et avaient un niveau de scolarisation moyen à élevé. Toutes les patientes ont bénéficié d'une consultation de génétique médicale au cours de laquelle il leur a été donné des informations sur la technique, son intérêt et ses limites. Il s'agit de femmes enceintes qui avaient soit un âge maternel élevé ou des signes d'appel échographiques et/ ou biochimiques. Une des patientes était porteuse d'une translocation robertsonienne t(14;21) équilibrée. Une amniocentèse a été réalisée chez toutes les gestantes et aucun avortement n'a était induit par ce geste invasif. L’âge gestationnel moyen à la première consultation était de 14 semaines d'aménorrhée (SA) et à l'amniocentèse était de 16 SA et 5 jours. L'analyse FISH a été réalisée, après consentement des couples, sur des cellules non cultivées à partir des échantillons de liquides amniotiques, en utilisant des sondes spécifiques du chromosome 21. Résultats Parmi les 23 patientes qui ont bénéficiées d'un diagnostic anténatal de la trisomie 21 par la technique FISH, nous avons pu rassurer 21 d'entre elles, et nous avons détecté deux cas de trisomie 21 fœtal. Conclusion La technique FISH permet un diagnostic anténatal rapide, en moins de 48h, de la trisomie 21 sur une faible quantité de liquide amniotique. Elle offre aux couples l'avantage de prendre, dans des délais raisonnables, la décision qui leur convient concernant la poursuite ou non de la grossesse. Elle permet souvent, avec un résultat normal, de rassurer rapidement les femmes enceintes trop angoissées. PMID:23330029

  4. APPEL DE COMMUNICATIONS la croise des chemins, les tudes sur

    E-print Network

    Farrell, Anthony P.

    APPEL DE COMMUNICATIONS À la croisée des chemins, les études sur l'alimentation : devant une bifurcation? SEPTIÈME ASSEMBLÉE GÉNÉRALE ANNUELLE DE L'ASSOCIATION CANADIENNE DES ÉTUDES SUR L'ALIMENTATION DU canadienne des sciences humaines, est « À la croisée des chemins, les études sur l'alimentation : devant une

  5. Vice-dcanat la recherche Rpertoire des projets

    E-print Network

    Laval, Université

    ........................................................................................................................ 18 Département des sciences des aliments et nutrition'agriculture, des pêcheries et de l'alimentation - 2008-05-08 au 2010-12-31 Réf. 91082 Chercheur(s) participant(s) # projet Montant Ministère de l'agriculture, des pêcheries et de l'alimentation GQ091082 DC 47 160

  6. Rapport annuel des activits de recherche 2008-2009

    E-print Network

    Laval, Université

    de l'alimentation Rapport annuel des activités de recherche 2008-2009 #12;#12;Page 3Rapport annuel des activités de recherche Faculté des sciences de l'agriculture et de l'alimentation Vice-décanat à la recherche Madame, Monsieur, Les chercheurs de la Faculté des sciences de l'agriculture et de l'alimentation

  7. Rapport annuel des activits de recherche 2010-2011

    E-print Network

    Laval, Université

    'équilibre parfait #12; #12;Faculté des sciences de l'agriculture et de l'alimentation Rapport annuel des activités sciences de l'agriculture et de l'alimentation Vice-décanat à la recherche Madame, Monsieur, Je suis très des activités de recherche 2010-2011 de la Faculté des sciences de l'agriculture et de l'alimentation

  8. Implantation des Espaces de Travail I. Introduction.............................................................. 82

    E-print Network

    Donsez, Didier

    Chapitre 5 Implantation des Espaces de Travail I. Introduction Persistantes.....................................88 IV. Structure MultiThreadée des Espaces de Travail.... 105 : Implantation des Espaces de Travail - 82 - I. Introduction L'implantation des Espaces de Travail est basée sur

  9. PORTRAIT DES PERCEPTIONS RELATIVES L'ENVIRONNEMENT CONOMIQUE PAR

    E-print Network

    Asselin, Hugo

    PORTRAIT DES PERCEPTIONS RELATIVES À L'ENVIRONNEMENT ÉCONOMIQUE PAR LES COMMERÇANTS ET QUÉBEC EN ABITIBI-TÉMISCAMINGUE CHAIRE DESJARDINS EN DÉVELOPPEMENT DES PETITES COLLECTIVITÉS PORTRAIT DES;iii SOMMAIRE Cette enquête vise à tracer un portrait des perceptions relatives à l

  10. Journe des Nouveaux Entrants INEE, Paris, 4 Juillet 2013

    E-print Network

    van Tiggelen, Bart

    OHM & SEEG Journée des Nouveaux Entrants INEE, Paris, 4 Juillet 2013 1 Journée des Nouveaux Entrants INEE, Paris, 4 Juillet 2013 #12;Présenter deux outils de l'INEE pour l'étude des (socio INEE, Paris, 4 Juillet 2013 #12;3 Journée des Nouveaux Entrants INEE, Paris, 4 Juillet 2013 Ecologie

  11. Dplacer des tas de terre En 3 dimensions.

    E-print Network

    Pansu, Pierre

    le long d'un mur. #12;Monge : mémoire sur la théorie des déblais et des remblais (1776) A l'un marchand forain. A 14 ans, il invente une pompe à incendie. A 17 ans, il revient dans son collège enseigner froid de 1776 Machine à remonter les bateaux Théorie des torrents et des rivières et moyen d

  12. Repliement des protéines : exemple de l'?-lactalbumine

    NASA Astrophysics Data System (ADS)

    Bushmarina, N. A.; Blanchet, C.; Vernier, G.; Forge, V.

    2005-11-01

    Cette revue sur le repliement des protéines ne fait appel à aucune expérience propre de diffusion de neutrons. Elle décrit les aspects cinétiques et thermodynamiques de la structuration des protéines sur leur chemin de repliement, en faisant référence à des techniques biophysiques variées permettant d'échantillonner des changements conformationnels sur des échelles de temps longues (ms. à s.). Les neutrons constituent une sonde évidemment complémentaire des techniques usuellement employées pour l'étude du repliement des protéines. Nous avons choisi un modèle d'étude, l'?-lactalbumine, pour donner un état de l'art des connaissances acquises à ce jour dans le domaine, et pour ainsi inciter biophysiciens et spectroscopistes à développer des techniques en temps résolu sur des échelles plus rapides, afin de pouvoir détecter les étapes précoces du repliement. Les neutrons doivent trouver une place logique dans de tels développements.

  13. Etude du stockage de l'hydrogene sur des nanostructures de carbone microporeuses

    NASA Astrophysics Data System (ADS)

    Poirier, Eric

    2007-12-01

    Le stockage de l'hydrogene par adsorption sur des adsorbants nano-structures a ete etudie sous differentes conditions de pression et de temperature. Les adsorbants etudies sont principalement des nanotubes de carbone a simple paroi ainsi que des structures metallo-organiques. Les mesures ont ete realisees a l'aide de systemes gravimetriques et volumetriques tres sensibles specialement mis au point pour de petits echantillons necessitant un degazage in situ. Les appareils developpes, au nombre de quatre, comprennent deux systemes gravimetriques et deux systemes volumetriques. Ensemble, ces systemes couvrent la plage de pressions (0-100) bars ainsi que la plage de temperatures (77-295) K. Les differentes analyses montrent que l'adsorption d'hydrogene sur les adsorbants nano-structures etudies est maximale a 77 K et varie entre environ (1.5 et 4) % masse. A temperature ambiante, l'adsorption croit lineairement avec la pression et demeure sous les 1% masse pour des pressions inferieures a 100 bars. L'adsorption d'hydrogene sur ces materiaux dans ces conditions se compare notamment a celle obtenue sur des charbons actives. La modelisation de l'adsorption a egalement ete realisee dans des conditions cryogeniques a l'aide du modele de Dubinin-Astakhov sous une forme adaptee pour l'adsorption supercritique. Les enthalpies d'adsorption calculees a partir de ce modele varient sous les 6 kJ/mole et sont donc consistantes avec des processus de physisorption. L'applicabilite du modele de Dubinin-Astakhov suggere que l'adsorption d'hydrogene puisse etre representee par un processus de remplissage des pores par un pseudo-liquide. Ces travaux s'inscrivent dans un contexte ou la capacite d'adsorption reelle des nanostructures de carbone est sujette a la controverse. En consequence, l'approche experimentale adoptee se distingue par les differentes demarches mises de l'avant pour l'obtention de mesures fiables sur des echantillons de faibles masses ainsi que par son caractere comparatif. Ces demarches incluent le developpement, l'etalonnage et la contreverification de systemes de mesures volumetriques et gravimetriques sensibles au microgramme. Ces systemes sont de plus adaptes au degazage sous vide et a haute temperature des echantillons. La mise au point d'un systeme de controle de temperature sur un petit volume pour des mesures a hautes pressions et basses temperatures constitue egalement un aspect original de ces travaux. De plus, d'un point de vue davantage theorique, cette these se caracterise par la modelisation de l'adsorption supercritique d'hydrogene sur differents materiaux et la derivation d'une expression pour l'enthalpie d'adsorption independante de la temperature a l'aide du modele de Dubinin-Astakhov.

  14. Rpertoire des emplois en dcembre 2011 Des diplms de Licence Professionnelle

    E-print Network

    Jeanjean, Louis

    gestion des automatismes (VEGA) (IUT de Belfort-Montbéliard) - Energie et génie climatique spécialité énergies renouvelables (IUT de Belfort-Montbéliard) - Gestion de la production industrielle spécialité

  15. Liquid level detector

    DOEpatents

    Grasso, Albert P. (Vernon, CT)

    1986-01-01

    A liquid level detector for low pressure boilers. A boiler tank, from which apor, such as steam, normally exits via a main vent, is provided with a vertical side tube connected to the tank at the desired low liquid level. When the liquid level falls to the level of the side tube vapor escapes therethrough causing heating of a temperature sensitive device located in the side tube, which, for example, may activate a liquid supply means for adding liquid to the boiler tank. High liquid level in the boiler tank blocks entry of vapor into the side tube, allowing the temperature sensitive device to cool, for example, to ambient temperature.

  16. Liquid level detector

    DOEpatents

    Grasso, A.P.

    1984-02-21

    A liquid level detector for low pressure boilers. A boiler tank, from which vapor, such as steam, normally exits via a main vent, is provided with a vertical side tube connected to the tank at the desired low liquid level. When the liquid level falls to the level of the side tube vapor escapes therethrough causing heating of a temperature sensitive device located in the side tube, which, for example, may activate a liquid supply means for adding liquid to the boiler tank. High liquid level in the boiler tank blocks entry of vapor into the side tube, allowing the temperature sensitive device to cool, for example, to ambient temperature.

  17. Semiconductor nanorod liquid crystals

    SciTech Connect

    Li, Liang-shi; Walda, Joost; Manna, Liberato; Alivisatos, A. Paul

    2002-01-28

    Rodlike molecules form liquid crystalline phases with orientational order and positional disorder. The great majority of materials in which liquid crystalline phases have been observed are comprised of organic molecules or polymers, even though there has been continuing and growing interest in inorganic liquid crystals. Recent advances in the control of the sizes and shapes of inorganic nanocrystals allow for the formation of a broad class of new inorganic liquid crystals. Here we show the formation of liquid crystalline phases of CdSe semiconductor nanorods. These new liquid crystalline phases may have great importance for both application and fundamental study.

  18. Actes des Journes des Jeunes Chercheurs en Systmes Mmoire Logiquement Partage, Toulouse, Septembre 1993. Des Espaces de Travail Distribus

    E-print Network

    Donsez, Didier

    , Septembre 1993. WEA, Des Espaces de Travail Distribués à Objets Persistants Didier Donsez, Philippe Homond, Des Espaces de Travail Distribués à Objets Persistants 2 Le système WEA utilise ce deux techniques'architecture client-serveur. Ce modèle est fondé sur un graphe d'espaces de travail dont chacun peut être

  19. Prendre le virage des partenariats.

    PubMed

    Sebestyen, Norma; Sulatycky, Ron; Rondos, Spyro; Davis, Sheila

    2015-11-01

    Deux projets démontrent que la mise en œuvre de données colligées sur le terrain peut contribuer à régler des problèmes dans le milieu de la santé pour favoriser de meilleurs résultats et de plus grandes efficiences. Dans le premier exemple, une vaste coalition de partenaires publics et privés de l'Alberta recourt aux techniques de mesures améliorées et à la méthodologie du Triple objectif pour améliorer les résultats cliniques de populations de cas complexes et lourds du quartier Eastwood d'Edmonton. On espère que les conclusions novatrices qui en sont tirées seront adaptées à d'autres régions de la province. Dans le deuxième exemple, la Childhood Obesity Foundation s'associe à Merck au Canada et à Ayogo (une société de thérapies numériques située à Vancouver) et utilise le concept novateur de la « ludification » pour mobiliser les jeunes de plus en plus sédentaires du Canada et modifier leurs comportements. PMID:26482219

  20. Restauration des pelouses calcaires Les abeilles solitaires

    E-print Network

    Rasmont, Pierre

    régulièrement plusieurs nids au cours de la saison (Jacob-Remacle 1989, 1990; Westrich 1989, 1990). Une fois suite à la récente interruption de l'activité d'extraction dans le courant des années 1990 (A. Remacle

  1. Fachprfungsordnung des Masterstudiengangs Health Care Management

    E-print Network

    Greifswald, Ernst-Moritz-Arndt-Universität

    Fachprüfungsordnung des Masterstudiengangs Health Care Management an der Ernst-Moritz-Arndt-Universität Greifs- wald die folgende Prüfungsordnung für den Masterstudiengang (M. Sc.) ,,Health Care Management Prüfungsverfahren im Studiengang ,,Health Care Management". Ergänzend gilt die Gemeinsame Prüfungsord- nung für

  2. Christian Blanchette Responsable de la gestion des

    E-print Network

    Charette, André

    Directeur de la gestion des programmes Richard St-Onge Directrice de la Formation continue Florence Bordage technopédagogique Justine Castonguay-Payant Coordonnateurs MICC Christiane Labelle Bernard Lévesque et Marco Moraes

  3. Écologie des soins de santé au Canada

    PubMed Central

    Stewart, Moira; Ryan, Bridget

    2015-01-01

    Résumé Objectif Présenter un profil populationnel pancanadien des besoins en soins de santé et de leur utilisation, facile d’accès et permettant des comparaisons entre les provinces et avec d’autres instances internationales. Conception Une comparaison des taux d’utilisation des soins de santé entre les provinces en utilisant des données d’enquêtes et des renseignements administratifs sur la santé. Contexte Les provinces du Canada. Principaux paramètres à l’étude Les taux canadiens et provinciaux de personnes en mauvaise santé (présence de problèmes chroniques) et d’utilisation des soins de santé (contacts avec des médecins de famille, avec d’autres médecins spécialistes, avec des infirmières et hospitalisations) sous forme de proportions mensuelles par 1000 habitants normalisées en fonction de l’âge et du genre. Résultats La proportion mensuelle par 1000 habitants de personnes souffrant d’au moins 1 problème chronique variait de 524 au Québec à 638 en Nouvelle-Écosse; les contacts avec un médecin de famille se situaient entre 158 au Québec et 295 en Colombie-Britannique; les contacts avec d’autres médecins spécialistes variaient entre 53 en Saskatchewan et 79 en Ontario; et le nombre de contacts avec des infirmières se situait entre 23 en Colombie-Britannique et 41 au Québec. Le nombre de séjours à l’hôpital variait entre 8 et 11 par 1000 habitants et les proportions étaient semblables d’une province à l’autre. Conclusion Il est essentiel de reconnaître les distinctions entre les provinces pour éclairer les politiques sur la santé dans l’ensemble du pays. Les différences persistaient lorsque les taux étaient normalisés en fonction de la composition démographique variable selon l’âge et le genre dans les provinces. Cet article présente une méthodologie simple à l’aide de données publiquement accessibles qui peut servir dans chaque province à examiner, à l’avenir, l’évolution avec le temps de l’utilisation des soins de santé par les instances provinciales.

  4. Die Erheblichkeit Des Humanismus In Durftiger Zeit

    E-print Network

    Kohak, Erazim

    Objekts wie ihn auch Auguste Comte verstanden hat. Die Kritik ist aber nicht stichhaltig gegenüber dem Positivismus des sinnhaften Erlebnisses, den Edmund Husserl in seinem Entwurf der Phänomenologie hervorbringt. Daher sind wir zu dem Schluß gekommen... ganz deutlich in Masaryks Humanismus geäussert, aber nicht nur dort. Der Gründer des modernen Positivismus, Auguste Com te, war auch derjenige Philosoph, der einen "Kult der Humanität" vorgeschlagen hat. Der britische Empirizist John Locke hat die...

  5. Elements de mecanique des milieux continus

    E-print Network

    Hauret, Patrice

    Chapitre 2 El´ements de m´ecanique des milieux continus Afin de faciliter la lecture du pr´esent travail et de formuler en totalit´e le probl`eme m´ecanique qui le motive, nous rappelons ici quelques ´el´etail compl´ementaire en ce qui concerne la m´ecanique des milieux continus, on pourra consulter les ouvrages

  6. Une petite1 histoire des nombres premiers

    E-print Network

    Jeanjean, Louis

    Une petite1 histoire des nombres premiers Vieux probl`emes et perc´ees r´ecentes Jean-Robert Belliard IREM Franche-Comt´e 1 Merci `a Nicolas Jacon Jean-Robert Belliard (IREM Franche-Comt´e) Une petite petite histoire des nombres premiers 2 / 31 #12;Qu'est ce qu'un nombre premier ? Jean-Robert Belliard

  7. Caracterisation des proprietes acoustiques des materiaux poreux a cellules ouvertes et a matrice rigide ou souple

    NASA Astrophysics Data System (ADS)

    Salissou, Yacoubou

    L'objectif global vise par les travaux de cette these est d'ameliorer la caracterisation des proprietes macroscopiques des materiaux poreux a structure rigide ou souple par des approches inverses et indirectes basees sur des mesures acoustiques faites en tube d'impedance. La precision des approches inverses et indirectes utilisees aujourd'hui est principalement limitee par la qualite des mesures acoustiques obtenues en tube d'impedance. En consequence, cette these se penche sur quatre problemes qui aideront a l'atteinte de l'objectif global precite. Le premier probleme porte sur une caracterisation precise de la porosite ouverte des materiaux poreux. Cette propriete en est une de passage permettant de lier la mesure des proprietes dynamiques acoustiques d'un materiau poreux aux proprietes effectives de sa phase fluide decrite par les modeles semi-phenomenologiques. Le deuxieme probleme traite de l'hypothese de symetrie des materiaux poreux selon leur epaisseur ou un index et un critere sont proposes pour quantifier l'asymetrie d'un materiau. Cette hypothese est souvent source d'imprecision des methodes de caracterisation inverses et indirectes en tube d'impedance. Le critere d'asymetrie propose permet ainsi de s'assurer de l'applicabilite et de la precision de ces methodes pour un materiau donne. Le troisieme probleme vise a mieux comprendre le probleme de transmission sonore en tube d'impedance en presentant pour la premiere fois un developpement exact du probleme par decomposition d'ondes. Ce developpement permet d'etablir clairement les limites des nombreuses methodes existantes basees sur des tubes de transmission a 2, 3 ou 4 microphones. La meilleure comprehension de ce probleme de transmission est importante puisque c'est par ce type de mesures que des methodes permettent d'extraire successivement la matrice de transfert d'un materiau poreux et ses proprietes dynamiques intrinseques comme son impedance caracteristique et son nombre d'onde complexe. Enfin, le quatrieme probleme porte sur le developpement d'une nouvelle methode de transmission exacte a 3 microphones applicable a des materiaux ou systemes symetriques ou non. Dans le cas symetrique, on montre que cette approche permet une nette amelioration de la caracterisation des proprietes dynamiques intrinseques d'un materiau. Mots cles. materiaux poreux, tube d'impedance, transmission sonore, absorption sonore, impedance acoustique, symetrie, porosite, matrice de transfert.

  8. Zero gravity liquid mixer

    NASA Technical Reports Server (NTRS)

    Booth, F. W.; Bruce, R. A. (inventors)

    1973-01-01

    An apparatus for mixing liquids under conditions of zero gravity is disclosed. The apparatus is comprised of a closed reservoir for the liquids, with a means for maintaining a positive pressure on the liquids in the reservoir. A valved liquid supply line is connected to the reservoir for supplying the reservoir with the liquids to be mixed in the reservoir. The portion of the reservoir containing the liquids to be mixed is in communication with a pump which alternately causes a portion of the liquids to flow out of the pump and into the reservoir to mix the liquids. The fluids in the reservoir are in communication through a conduit with the pump which alternately causes a portion of the fluids to flow out of the pump and into the sphere. The conduit connecting the pump and sphere may contain a nozzle or other jet-forming structure such as a venturi for further mixing the fluids.

  9. Profil épidémiologique des tumeurs malignes primitives des glandes salivaires : à propos de 154 cas

    PubMed Central

    Setti, Khadija; Mouanis, Mohamed; Moumni, Abdelmounim; Maher, Mostafa; Harmouch, Amal

    2014-01-01

    Introduction Les tumeurs des glandes salivaires sont des tumeurs rares représentant 3à 5% des tumeurs de la tête et du cou. La classification de l'OMS 2005 distingue les tumeurs épithéliales, les tumeurs mésenchymateuses, les tumeurs hématologiques et les tumeurs secondaires. Méthodes Notre travail consiste en une étude rétrospective réalisée sur une période de 10 ans allant de janvier 2002 à janvier 2012. Les critères d'inclusion étaient: l'âge, le sexe, le siège de la tumeur et le type histologique. Résultats L'incidence annuelle des tumeurs malignes primitives des glandes salivaires dans notre série était de 15 cas par an. Cent cinquante quatre cas de tumeurs malignes primitives des glandes salivaires ont été colligés sans prédominance de sexe (78 femmes (50,6%) et 76 hommes (49,4%)). La moyenne d'âge était de 60 ans avec des extrêmes de 4 et 83 ans et un pic de fréquence entre 51et 70 ans. Deux tiers des cas (65%) avaient une localisation au niveau des glandes principales avec 66 cas au niveau de la parotide (43%) et 34 cas au niveau de la glande sous maxillaire (22%). Cinquante quatre patients avaient une tumeur maligne des glandes salivaires accessoires (35%) dont 61% au niveau du palais. Aucun cas de tumeur maligne de la glande sublinguale n'a été recensé dans notre étude. Le type histologique prédominant dans notre série était le carcinome adénoïde kystique et retrouvé chez 43 patients (27,9%), suivi de l'adénocarcinome sans autre indication chez 37 patients (24%) puis du carcinome mucoépidermoïde chez 16 patients (10,4%) et de l'adénocarcinome polymorphe de bas grade également chez 16 patients (10. 4%). Conclusion Les tumeurs malignes des glandes salivaires représentent un ensemble hétérogène de maladies de caractérisation complexe et de fréquence variable. PMID:25120861

  10. La microscopie ionique analytique des tissus biologiques

    NASA Astrophysics Data System (ADS)

    Galle, P.

    Proposed in 1960 by R. Castaing and G. Slodzian, secondary ion emission microanalysis is a microanalytical method which is now largely used for the study of inert material. The instrument called the analytical ion microscope can also be used for the study of biological spécimens ; images representing the distribution of a given stable or radioactive isotope in a tissue section are obtained with a resolution of 0.5 ?m. Among the characteristics of this method, two are of particular interest in biological research : its capacity for isotopic analysis and its very high sensitivity which makes possible for the first time a chemical analysis of element at a very low or even at a trace concentration in a microvolume. Proposé en 1960 par R. Castaing et G. Slodzian, la microanalyse par émission ionique secondaire est une méthode qui permet, entre autre, d'obtenir des images représentant la distribution des isotopes présents à la surface d'un échantillon solide avec une résolution de 0,5 ?m. D'intérêt très général, cette méthode a été d'abord largement utilisée pour l'étude des matériaux inertes. Elle offre en outre des possibilités entièrement nouvelles dans le domaine de la recherche biomédicale. L'instrument réalisé, le microscope ionique analytique présente deux caractéristiques particulièrement intéressantes pour la biologie : la possibilité d'analyse isotopique, et l'extrême sensibilité permettant de détecter et de localiser dans une coupe histologique des éléments à des concentrations très faibles voire à l'état de trace.

  11. Des ports, des ports, encore des ports ? En Mditerrane, le plateau continental est gnralement troit, de telle sorte que les fonds de

    E-print Network

    Boudouresque, Charles F.

    Des ports, des ports, encore des ports ? En Méditerranée, le plateau continental est généralement Sahara. Tous les aménagements littoraux (ports, endigages, plages artificielles) sont concentrés sur les port tous les 7 km de côte ; ce chiffre tombe à 5 km en région PACA, et à 3 km si l'on considère le

  12. Karen Wiebe, Ph. D. ur les rives des lacs, des tangs et des cours d'eau, les sols sont humides et fertiles et

    E-print Network

    Karen Wiebe, Ph. D. Chercheure S U s s s s photo of researcher ur les rives des lacs, des étangs et des cours d'eau, les sols sont humides et fertiles et la végétation est abondante et variée. Cet habitat est peuplé d'animaux de toutes sortes, qui peuvent y chercher refuge contre leurs prédateurs et y

  13. Elaboration d'un environnement d'experimentation en simulation incluant un cadre theorique pour l'apprentissage de l'energie des fluides

    NASA Astrophysics Data System (ADS)

    Cervera, Daniel

    Dans cette these, nous presentons la demarche et les diverses etapes qui nous ont conduits a l'elaboration d'un environnement d'experimentation en simulation assistee par ordinateur, incluant un cadre theorique, susceptible d'ameliorer l'apprentissage des concepts relies aux phenomenes qui se produisent dans les systemes technologiques fermes impliquant des fluides (gaz et liquides), tels les systemes hydrauliques et pneumatiques industriels, les systemes de refrigeration, de climatisation et de chauffage. Ces phenomenes ne sont pas directement observables et leur evolution obeit aux interactions complexes qui se produisent a l'interieur des systemes, ce qui leur confere un caractere particulierement abstrait et difficile a comprendre. Notre demarche a consiste a concevoir cet environnement d'apprentissage a partir d'une situation problematique qui se caracterise notamment par la presence de fausses representations conceptuelles chez les etudiants et par la complexite des phenomenes impliques dans les systemes en question. Nous avons conceptualise un environnement d'apprentissage interactif d'inspiration essentiellement constructiviste, base sur l'experimentation et la modelisation didactique et qui permet a l'etudiant d'observer simultanement et en temps reel le comportement des systemes et l'evolution des variables au moyen de graphiques. Aussi, nous avons elabore un cadre theorique pour l'apprentissage de l'energie des fluides, de nature semblable a celui qui existe pour les circuits electriques. Ce cadre theorique explicite les regles qui sous-tendent la maniere dont les fluides se distribuent dans les circuits et permet d'articuler une analyse du comportement des systemes. Nous avons realise deux prototypes de l'environnement d'apprentissage. Le premier a permis de verifier la faisabilite technologique et l'interet didactique des principales orientations du projet. Le deuxieme prototype a ete concu et realise dans le cadre d'une entente de partenariat de type industriel avec deux autres co-auteurs. Nous avons effectue les mimses a l'essai fonctionnelle et empirique des prototypes selon la demarche du modele de recherche-developpement technologique en education de Nonnon. Les resultats de ces mises a l'essai indiquent que l'environnement d'apprentissage illustre le comportement des systemes selon un degre de fidelite technologique suffisamment proche de celui des systemes reels, en plus d'offrir les avantages propres a la simulation assistee par ordinateur, c'est-a-dire notamment la possibilite de creer des situations et de les experimenter, d'en faire varier les parametres, d'illustrer les phenomenes caches et d'observer simultanement et en temps reel le comportement des systemes et l'evolution des graphiques des variables. Les caracteristiques technologiques qui decoulent des techniques avancees de modelisation utilisees pour la realisation du deuxieme prototype, conferent a l'environnement d'apprentissage des capacites reliees a la conception de systemes et au diagnostic de pannes en milieu industriel. Cet aspect, que nous n'avions pas poursuivi specifiquement au plan didactique, constitue, selon nous, un serieux indice de sa valeur en tant que milieu d'etude representatif des systemes reels.

  14. High Performance Liquid Chromatography

    E-print Network

    Nizkorodov, Sergey

    HPLC - 1 High Performance Liquid Chromatography HPLC MEASUREMENT OF POLYCYCLIC AROMATIC HYDROCARBONS IN CIGARETTE SMOKE Last updated: June 17, 2014 #12;HPLC - 2 High Performance Liquid Chromatography identify as many PAH as possible in cigarette smoke using high performance liquid chromatography (HPLC

  15. Making Liquid Oxygen

    E-print Network

    French, M M J

    2010-01-01

    In this article I explain in detail a method for making small amounts of liquid oxygen in the classroom if there is no access to a cylinder of compressed oxygen gas. I also discuss two methods for identifying the fact that it is liquid oxygen as opposed to liquid nitrogen.

  16. Breakup of Liquid Filaments

    E-print Network

    Castrejon-Pita, Alfonso A.; Castrejon-Pita, J. R.; Hutchings, I. M.

    2012-01-01

    Charles Babbage Road, Cambridge, CB3 0FS, U.K. Whether a thin filament of liquid separates into two or more droplets or eventually condenses lengthwise to form a single larger drop depends on the liquid’s density, viscosity and surface tension...

  17. Renewable liquid reflection grating

    DOEpatents

    Ryutov, Dmitri D.; Toor, Arthur

    2003-10-07

    A renewable liquid reflection grating. Electrodes are operatively connected to a conducting liquid in an arrangement that produces a reflection grating and driven by a current with a resonance frequency. In another embodiment, the electrodes create the grating by a resonant electrostatic force acting on a dielectric liquid.

  18. Liquid detection circuit

    DOEpatents

    Regan, Thomas O. (North Aurora, IL)

    1987-01-01

    Herein is a circuit which is capable of detecting the presence of liquids, especially cryogenic liquids, and whose sensor will not overheat in a vacuum. The circuit parameters, however, can be adjusted to work with any liquid over a wide range of temperatures.

  19. Influence de la dépendance en température des propriétés optiques des matériaux sur la force de Casimir

    NASA Astrophysics Data System (ADS)

    Joulain, K.; Henkel, C.; Greffet, J.-J.

    2006-10-01

    Nous évaluons la force de Casimir entre deux surfaces planes métalliques constituées d'argent. Nous prenons, pour effectuer cette évaluation, des propriétés optiques de l'argent à différentes températures [1]. Nous montrons que cette dépendance en température modifie la force de Casimir (de 0.2%) y compris à des distances inférieures à la longueur d'onde thermique.

  20. Polythiophènes substitués par des motifs tétrathiafulvalènes : vers des matériaux électroactifs à conductivité mixte

    NASA Astrophysics Data System (ADS)

    Huchet, L.; Roncali, J.

    1998-06-01

    Highly electroactive conjugated polymers have been synthesized by electropolymerisation of tetrathiafulvalene-derivatised bithiophenes. We report and discuss the electrochemical and optical properties of these new polymers. Des polymères conjugués fortement électroactifs ont été synthétisés par électropolymérisation de bithiophènes dérivés du tétrathiafulvalène. Nous présentons et discutons des caractéristiques électrochimiques et optiques de ces nouveaux polymères.

  1. BIO3515 -Biologie de la conservation des espces BIO 3515 Biologie de la conservation des espces

    E-print Network

    Blouin-Demers, Gabriel

    BIO3515 - Biologie de la conservation des espèces BIO 3515 ­ Biologie de la de Biologie Department of Biology Université d'Ottawa University of Ottawa 30 Marie-Curie Ottawa ! de !1 11 #12;BIO3515 - Biologie de la conservation des espèces 1 -- Après votre solide

  2. Premire pierre des futurs btiments de la Maison des sciences de l'homme et de

    E-print Network

    Jeanjean, Louis

    1 Première pierre des futurs bâtiments de la Maison des sciences de l'homme et de l par la Préfecture de Région et le Rectorat de l'Académie de Franche-Comté, préconisait : "Enfin, il faudrait structurer et dynamiser la recherche en sciences humaines et sociales à travers la création d

  3. DYNAMIQUE DES SYST`EMES D'ISOM'ETRIES : SUR LES BOUTS DES ORBITES

    E-print Network

    Gaboriau, Damien

    DYNAMIQUE DES SYST`EMES D'ISOM'ETRIES : SUR LES BOUTS DES ORBITES Damien Gaboriau Un syst`eme d'isom'etries (de dimension un) est une r'eunion finie D d'interv* *alles compacts de R, munie d'une famille finie '1, '2, . .,.'k d'isom

  4. Contrle pour des systmes gouverns par des quations aux drives partielles

    E-print Network

    Jeanjean, Louis

    à vapeurs (J. Watt en 1769), etc Voir l'article de James Clerk Maxwell dont l'article On governors), régulation de vitesse des machines à vapeurs (J. Watt en 1769), etc Voir l'article de James Clerk Maxwell vitesse des machines à vapeurs (J. Watt en 1769), etc Voir l'article de James Clerk Maxwell dont l

  5. Dtection robuste et automatique des contours myocardiques sur des squences IRM cardiaques marques

    E-print Network

    Histace, Aymeric

    Détection robuste et automatique des contours myocardiques sur des séquences IRM cardiaques et le suivi de patho- logies cardio-vasculaires. L'IRM cardiaque marquée (ou taggée) permet de satisfying results in term of precision but also in term of reproducibility. 1 Introduction L'IRM de marquage

  6. EXTRACTION DE CONNAISSANCES PARTIR DES DONNEES ET DES TEXTES (ECD ET ECT "DATA & TEXT MINING")

    E-print Network

    Spagnolo, Filippo

    1 EXTRACTION DE CONNAISSANCES � PARTIR DES DONNEES ET DES TEXTES (ECD ET ECT "DATA & TEXT MINING'Extraction de Connaissances à partir de Données (ECD, "Data Mining"). Le point fondamental qui distingue ces IN DATA AND TEXTS," defines Knowledge Discovery in Texts (KDT, or Text Mining, TM) as a continuation

  7. Communiqu de presse 17 fvrier 2015 Impact grande chelle des pesticides

    E-print Network

    attendu, mais aussi dans ceux traités par des herbicides. A l'inverse, ces insectes sont plus abondants-limaces. Si l'impact des insecticides sur les insectes est direct, celui des herbicides serait indirect, en sont moins abondants dans les parcelles agricoles traitées par des herbicides, des insecticides ou des

  8. Radiation monitor for liquids

    DOEpatents

    Koster, J.E.; Bolton, R.D.

    1999-03-02

    A radiation monitor for use with liquids that utilizes air ions created by alpha radiation emitted by the liquids as its detectable element. A signal plane, held at an electrical potential with respect to ground, collects these air ions. A guard plane or guard rings is used to limit leakage currents. In one embodiment, the monitor is used for monitoring liquids retained in a tank. Other embodiments monitor liquids flowing through a tank, and bodies of liquids, such as ponds, lakes, rivers and oceans. 4 figs.

  9. Developpement des betons semi autoplacants a rheologie adaptee pour des infrastructures

    NASA Astrophysics Data System (ADS)

    Sotomayor Cruz, Cristian Daniel

    Au cours des dernières décennies, les infrastructures canadiennes et québécoises comportent plusieurs structures en béton armé présentant des problèmes de durabilité dus aux conditions climatiques sévères, à la mauvaise conception des structures, à la qualité des matériaux, aux types des bétons choisis, aux systèmes de construction ou à l'existence d'événements incontrôlables. En ce qui concerne le choix du béton pour la construction des infrastructures, une vaste gamme de béton divisée en deux principaux types peut être utilisée: le béton conventionnel vibré (BCV) et le béton autoplaçant (BAP). Dans le cas d'un BCV, la consolidation inadéquate par vibration a été un problème récurrent, occasionnant des dommages structuraux. Ceci a conduit à une réduction de la durabilité et à une augmentation du coût d'entretien et de réparation des infrastructures. Rien que l'utilisation d'un BAP a des avantages tels que l'élimination de la vibration, la réduction des coûts de main d'oeuvre et l'amélioration de la qualité des structures, néanmoins, le coût initial d'un BAP par rapport à un BCV ne permet pas encore de généraliser son utilisation dans l'industrie de la construction. Ce mémoire présente la conception d'une nouvelle gamme de béton semi-autoplaçant pour la construction des infrastructures (BSAP-I) exigeant une vibration minimale. Il s'agit de trouver un équilibre optimal entre la rhéologie et le coût initial du nouveau béton pour conférer une bonne performance structurale et économique aux structures. Le programme expérimental établi a premièrement permis d'évaluer la faisabilité d'utilisation des BSAP-I pour la mise en place des piliers d'une infrastructure de pont à Sherbrooke. En plus, l'utilisation d'un plan d'expériences a permis l'évaluation de trois paramètres de formulation sur les propriétés des mélanges de BSAP-I à l'état frais et durci. Finalement, l'évaluation de la performance des BSAP-I optimisés à travers une caractérisation complète des propriétés mécaniques et de la durabilité a été réalisée. A la suite de cette étude, les résultats obtenus nous permettent de conclure que : (1) L'utilisation d'un BSAP-I avec un gros granulat de 5 - 14 mm, des rapports E/L = 0,37 et S/G = 0,52 et une teneur en air de 6 à 9% a été possible en conférant un équilibre optimal fluidité / stabilité à l'état frais, ainsi qu'un niveau de thixotropie adéquate au chantier permettant d'optimiser la conception du coffrage des piliers de pont et de conférer des qualités de surfaces très acceptables de ces infrastructures. (2) La méthode adaptée pour l'essai L-Box contenant 2 barres et une vibration de 5 secondes a permis de bien caractériser la capacité de remplissage d'un BSAP-I. (3) L'utilisation d'un plan factoriel 23 a permis d'obtenir des modèles statistiques fiables, capables de prédire les propriétés rhéologiques à l'état frais et les résistances en compression des BSAP-I avec des dosages en liant entre 370 et 420 kg/m3, des rapports E/L entre 0,34 et 0,40 et S/G entre 0,47 et 0,53. (4) Des mesures de vitesse d'écoulement T40 d'un BSAP-I sont très semblables à celles d'un BAP. En plus, des valeurs T40 montrent une bonne corrélation linéaire avec celles de T400 mesurés dans la boîte L-Box. (5) À la frontière du BAP et du BCV, une bande rhéologique possédant un ?0 entre 30 et 320 Pa et un ? entre 10 et 140 Pa.s a été trouvée pour la conception optimale des BSAP-I. (6) Les BSAP-I optimisés ont également conféré une très bonne performance à l'état frais, en permettant maintenir un bon équilibre entre la rhéologie et la stabilité dans le temps, lorsqu'on utilise une énergie de vibration minimale pour amorcer son écoulement. (7) À l'état durci Les BSAP-I ont conféré une bonne performance présentant des résistances mécaniques élevées et des niveaux négligeables de pénétration aux ions chlores, de perte de masse par écaillage et des attaques par le gel/dégel. (8) L'utilisation des cim

  10. Emulsification liquid-liquid microextraction based on deep eutectic solvent: An extraction method for the determination of benzene, toluene, ethylbenzene and seven polycyclic aromatic hydrocarbons from water samples.

    PubMed

    Khezeli, Tahere; Daneshfar, Ali; Sahraei, Reza

    2015-12-18

    In this study, for the first time, a simple, inexpensive and sensitive method named emulsification liquid-liquid microextraction based on deep eutectic solvent (ELLME-DES) was used for the extraction of benzene, toluene, ethylbenzene (BTE) and seven polycyclic aromatic hydrocarbons (PAHs) from water samples. In a typical experiment, 100?L of DES (as water-miscible extraction solvent) was added to 1.5mL of sample solution containing target analytes. A homogeneous solution was formed immediately. Injection of 100?L of THF (as emulsifier agent) into homogeneous solution provided a turbid state. After extraction, phase separation (aqueous phase/DES rich phase) was performed by centrifugation. DES rich phase was withdrawn by a micro-syringe and submitted to isocratic reverse-phase HPLC with UV detection. Under optimum conditions obtained by response surface methodology (RSM) and desirability function (DF), the calibration graphs were linear in the concentration range from 10 to 200?g/L for benzene, 10-400?g/L for toluene, 1-400?g/L for ethylbenzene, biphenyl, chrysene and fluorene, and 0.1-400?g/L for anthracene, benzo[a]pyrene, phenanthrene and pyrene. The coefficients of determination (r(2)) and limits of detection were 0.9924-0.9997 and 0.02-6.8?g/L, respectively. This procedure was successfully applied to the determination of target analytes in spiked water samples. The relative mean recoveries ranged from 93.1 to 103.3%. PMID:26614169

  11. Liquid Wall Chambers

    SciTech Connect

    Meier, W R

    2011-02-24

    The key feature of liquid wall chambers is the use of a renewable liquid layer to protect chamber structures from target emissions. Two primary options have been proposed and studied: wetted wall chambers and thick liquid wall (TLW) chambers. With wetted wall designs, a thin layer of liquid shields the structural first wall from short ranged target emissions (x-rays, ions and debris) but not neutrons. Various schemes have been proposed to establish and renew the liquid layer between shots including flow-guiding porous fabrics (e.g., Osiris, HIBALL), porous rigid structures (Prometheus) and thin film flows (KOYO). The thin liquid layer can be the tritium breeding material (e.g., flibe, PbLi, or Li) or another liquid metal such as Pb. TLWs use liquid jets injected by stationary or oscillating nozzles to form a neutronically thick layer (typically with an effective thickness of {approx}50 cm) of liquid between the target and first structural wall. In addition to absorbing short ranged emissions, the thick liquid layer degrades the neutron flux and energy reaching the first wall, typically by {approx}10 x x, so that steel walls can survive for the life of the plant ({approx}30-60 yrs). The thick liquid serves as the primary coolant and tritium breeding material (most recent designs use flibe, but the earliest concepts used Li). In essence, the TLW places the fusion blanket inside the first wall instead of behind the first wall.

  12. Liquid Metal Transformers

    E-print Network

    Sheng, Lei; Liu, Jing

    2014-01-01

    The room temperature liquid metal is quickly emerging as an important functional material in a variety of areas like chip cooling, 3D printing or printed electronics etc. With diverse capabilities in electrical, thermal and flowing behaviors, such fluid owns many intriguing properties that had never been anticipated before. Here, we show a group of unconventional phenomena occurring on the liquid metal objects. Through applying electrical field on the liquid metals immersed in water, a series of complex transformation behaviors such as self-assembling of a sheet of liquid metal film into a single sphere, quick mergences of separate metal droplets, controlled self-rotation and planar locomotion of liquid metal objects can be realized. Meanwhile, it was also found that two accompanying water vortexes were induced and reliably swirled near the rotating liquid metal sphere. Further, effects of the shape, size, voltage, orientation and geometries of the electrodes to control the liquid metal transformers were clar...

  13. Liquid Propellant Manipulated Acoustically

    NASA Technical Reports Server (NTRS)

    Oeftering, Richard C.; Chato, David J.; Mann, Adin, III

    2003-01-01

    Fluids are difficult to manage in the space environment. Without gravity, the liquid and gas do not always remain separated as they do in the 1g environment of Earth. Instead the liquid and gas volumes mix and migrate under the influence of surface tension, thermodynamic forces, and external disturbances. As a result, liquid propellants may not be in a useable location or may even form a chaotic mix of liquid and gas bubbles. In the past, mechanical pumps, baffles, and a variety of specialized passive devices have been used to control the liquid and gas volumes. These methods need to be carefully tuned to a specific configuration to be effective. With increasing emphasis on long-term human activity in space there is a trend toward liquid systems that are more flexible and provide greater control. We are exploring new methods of manipulating liquids by using the nonlinear acoustic effects achieved by using beams of highly directed high-intensity acoustic waves.

  14. Intensification of Liquid-Liquid Contacting Processes

    E-print Network

    Qiu, Zheyan

    2010-09-01

    transfer was intensified by the application of electric fields. As an alternative biofuel, biodiesel is produced through transesterification of vegetable oils, fat and algae lipids and alcohol with the help of acid or base. Transesterification is a liquid...

  15. Deep eutectic solvent (DES) as a pretreatment for oil palm empty fruit bunch (OPEFB) in production of sugar

    NASA Astrophysics Data System (ADS)

    Nor, Nur Atikah Md; Mustapha, Wan Aida Wan; Hassan, Osman

    2015-09-01

    Oil Palm Empty Fruit Bunch (OPEFB) was pretreated using Deep Eutectic Solvent (DES) at different parameters to enable a highest yield of sugar. DES is a combination of two or more cheap and safe components to form a eutectic mixture through hydrogen bond interaction, which has a melting point lower than that of each component. DES can be used to replace ionic liquids (ILs), which are more expensive and toxic. In this study, OPEFB was pretreated with DES mixture of choline chloride: urea in 1:2 molar ratio. The pretreatment was performed at temperature 110°C and 80°C for 4 hours and 1 hour. Pretreatment A (110°C, 4 hours), B (110°C, 1 hour), C (80°C, 4 hours) and D (80°C, 1 hour). Enzymatic hydrolysis was done by using the combination of two enzymes, namely, Cellic Ctec2 and Cellic Htec2. The treated fiber is tested for crystallinity using XRD and functional group analysis using FTIR, to check the effect of the pretreatment on the fiber and compared it with the untreated fiber. From XRD analysis, DES successfully gave an effect towards degree of crystallinity of cellulose. Pretreatment A (110°C, 4 hours) and B (110°C, 1 hour) successfully reduce the percentage of crystallinity while pretreatment C (80°C, 4 hours) and D (80°C, 1 hour) increased the percentage of crystallinity. From FTIR analysis, DES cannot remove the functional group of lignin and hemicellulose but it is believed that DES can expose the structure of cellulose. Upon enzymatic hydrolysis, DES-treated fiber successfully produced sugar but not significantly when compared with raw. Pretreatment A (110°C, 4 hours), B (110°C, 1 hour), C (80°C, 4 hours) and D (80°C, 1 hour) produced glucose at the amount of 60.47 mg/ml, 66.33 mg/ml, 61.96 mg/ml and 59.12 mg/ml respectively. However, pretreatment C gave the highest xylose (70.01 mg/ml) production compared to other DES pretreatments.

  16. Modeling Liquid-Liquid Equilibrium of Ionic Liquid Systems with NRTL, Electrolyte-NRTL, and UNIQUAC

    E-print Network

    Stadtherr, Mark A.

    temperature ionic liquids (ILs). ILs are generally defined as organic salts with melting temperatures belowModeling Liquid-Liquid Equilibrium of Ionic Liquid Systems with NRTL, Electrolyte-NRTL, and UNIQUAC: markst@nd.edu #12;Abstract Characterization of liquid-liquid equilibrium (LLE) in system containing ionic

  17. Kurzbericht ber die formative Evaluation des Lehrmittels Mathematik Primarstufe

    E-print Network

    Steiner, Daniel

    Kurzbericht über die formative Evaluation des Lehrmittels «Mathematik Primarstufe» «Das ist für CH-8090 Zürich Zürcher Fachhochschule Juli 2013 #12;Kurzbericht über die formative Evaluation des Lehrmittels «Mathematik Primarstufe» 2PH Zürich| Vorwort Dieser Bericht möchte Lehrpersonen über die

  18. Bemerkungen zu einem gewissen Auszug des Descartes, der sich auf

    E-print Network

    Leonhard Euler In den Auszügen aus den Manuskripten von Descartes wird zwar in we- nigen Worten eine Rahmen des Projektes ,,Euler-Kreis Mainz" 1 #12;dem vierten Teil des vorhergehenden; und auf dieselbe

  19. Le contrôle des infections au cabinet du pédiatre

    PubMed Central

    2008-01-01

    RÉSUMÉ La transmission des infections au cabinet du pédiatre est de plus en plus préoccupante. Le présent document expose les voies de transmission des infections et les principes sous-jacents aux mesures actuelles pour contrôler les infections. Pour prévenir les infections, il faut bien concevoir le cabinet et adopter des politiques administratives et de triage convenables, de même que des pratiques de base pour les soins de tous les patients (p. ex., hygiène des mains, port de gants, de masques, de lunettes de protection et d’une blouse d’hôpital pour des interventions précises; nettoyage, désinfection et stérilisation convenables des surfaces et du matériel, y compris les jouets, et techniques d’asepsie en cas d’interventions effractives) et des précautions additionnelles en cas d’infections précises. Le personnel doit avoir reçu les vaccins pertinents, et les personnes infectées doivent respecter les politiques de restriction au travail.

  20. Systemtherapie des metastasierten malignen Melanoms.

    PubMed

    Rauschenberg, Ricarda; Garzarolli, Marlene; Dietrich, Ursula; Beissert, Stefan; Meier, Friedegund

    2015-12-01

    Für Patienten mit metastasiertem Melanom stehen aktuell mehrere wirksame Therapieoptionen zur Verfügung. Die BRAF-Inhibitoren Vemurafenib und Dabrafenib zeichnen sich durch eine rasche Tumorkontrolle und hohe Ansprechraten aus. In Kombination mit den MEK-Inhibitoren Trametinib bzw. Cobimetinib erreichen sie Ansprechraten (CR + PR, komplette plus partielle Remissionen) von 70 %, wobei die Entwicklung einer Therapieresistenz verzögert wird, sowie ein medianes Gesamtüberleben von > 2 Jahren bei tolerablen Nebenwirkungen. Der CTLA-4-Antikörper Ipilimumab erzielte für Patienten mit metastasiertem Melanom als erste Substanz eine signifikante Verlängerung des Gesamtüberlebens (Langzeitüberlebensrate: 20-26 %). Verzögertes Therapieansprechen und schwere immunvermittelte Nebenwirkungen können den therapeutischen Benefit einschränken. Die Monotherapie mit den PD-1-Antikörpern Nivolumab oder Pembrolizumab erreicht Ansprechraten (CR + PR) bis zu 45 % und 1-Jahres-Überlebensraten von > 70 % bei meist guter Verträglichkeit. Die Kombination Ipilimumab plus Nivolumab zeigte Ansprechraten bis zu 58 % und ein medianes progressionsfreies Überleben von > 11 Monaten. Von dieser Kombination wird ein zeitnahes und lang anhaltendes Ansprechen erwartet. Dieser potenzielle Benefit wird durch eine hohe Toxizität erkauft. Aktuell werden in klinischen Studien Strategien für Therapiesequenz und -kombinationen geprüft. Insgesamt hat sich die Prognose für Patienten mit metastasiertem Melanom signifikant verbessert. In Anbetracht eines möglichen Langzeitüberlebens müssen neben akuten Nebenwirkungen auch die Langzeit-Nebenwirkungen einer Behandlung berücksichtigt werden. PMID:26612790

  1. Vice-dcanat la recherche Rpertoire des projets

    E-print Network

    Laval, Université

    ........................................................................................................................ 22 Département des sciences des aliments et nutrition projet Contrat - Ministère de l'agriculture, des pêcheries et de l'alimentation - 2011-03-15 au 2011 et de l'alimentation GQ098515 CC 11 000,00$ Financement global 11 000,00$ LAMBERT, Rémy Projet

  2. JARDIN DES PLANTES 57 RUE CUVIER, PARIS 5e

    E-print Network

    des adaptations humaines, en termes de locomotion et d'alimentation, au cours de l'évolution. Celles. 2. Alimentation et digestion. Diversité des régimes alimentaires et des niches écologiques, saisonnalité, alimentation et santé. Coévolution avec les plantes, automédication. 3. Comportement, vie sociale

  3. Accs au texte intgral des articles depuis Lyon1

    E-print Network

    Maume-Deschamps, Véronique

    Accès au texte intégral des articles depuis Lyon1 Accès au texte intégral par le résolveur de liens résolveur de liens en cliquant sur l'une des icônes : 1 #12;Accès au texte intégral des articles depuis Lyon texte intégral d'un article / portail de la BU 3 Référence de l'article Titre de la revue Site web de la

  4. www.cnrs.fr Des virus mergents aux virus pandmiques

    E-print Network

    van Tiggelen, Bart

    JACQUES-MONOD Institut des sciences biologiques Institut écologie et environnement Information Secrétariat des Conférences Jacques-Monod CNRS Institut des sciences biologiques 3, rue Michel-Ange, F-75794 Paris Cedex 16, France E-mail : conf.monod@cnrs-dir.fr http://www.cnrs.fr/insb/cjm/ #12;

  5. PLC IMPLEMENTATION OF A DES SUPERVISOR FOR A MANUFACTURING

    E-print Network

    Leduc, Ryan

    PLC IMPLEMENTATION OF A DES SUPERVISOR FOR A MANUFACTURING TESTBED: AN IMPLEMENTATION PERSPECTIVE Copyright by Ryan James Leduc 1996 #12;Title: PLC Implementation of A DES Supervisor for a Manufacturing, and issues involved in implementing DES supervisors on programmable logic controllers (PLC). A PLC based

  6. Geschftsordnung des Audit Committees der Universitt Zrich Geschftsordnung

    E-print Network

    Zürich, Universität

    Geschäftsordnung des Audit Committees der Universität Zürich Geschäftsordnung des Audit Committee der Universität Zürich (vom 20. August 2007) § 1 Ziel und Zweck Das Audit Committee unterstützt den Revision führt im Auftrag des Audit Committee die Revisionen durch. Sie ist fachlich dem Audit Committee

  7. 0. Informationen zur Vorlesung 0-1 Grundlagen des

    E-print Network

    Brass, Stefan

    . Stefan Brass Institut f¨ur Informatik ¨Ubungen: Dr. Henning Thielemann Stefan Brass: Grundlagen des World) · Suchmaschinen (kurz) Stefan Brass: Grundlagen des World Wide Web Universit¨at Halle, 2009 #12;0. Informationen Brass: Grundlagen des World Wide Web Universit¨at Halle, 2009 #12;0. Informationen zur Vorlesung 0

  8. 0. Informationen zur Vorlesung 0-1 Grundlagen des

    E-print Network

    Brass, Stefan

    . Stefan Brass Institut f¨ur Informatik ¨Ubungen: Dr. Henning Thielemann Stefan Brass: Grundlagen des World) · Suchmaschinen (kurz) Stefan Brass: Grundlagen des World Wide Web Universit¨at Halle, 2010 #12;0. Informationen Brass: Grundlagen des World Wide Web Universit¨at Halle, 2010 #12;0. Informationen zur Vorlesung 0

  9. Autour des services web Georges-Andr SILBER

    E-print Network

    Silber, Georges-André

    structures. #12;L'invention du Web · 1989:Tim Berners-Lee travaille au CERN et invente le Web · 1994'art des technologies Web : description- egypte.org #12;Tim Berners-Lee · Le père du WWW · Inventeur des de Tim en 1990 sur un ordinateur NeXT #12;HTML · Création d'un nouveau langage pour représenter des

  10. Electrically actuated liquid iris.

    PubMed

    Xu, Miao; Ren, Hongwen; Lin, Yi-Hsin

    2015-03-01

    We report an adaptive iris using dielectric liquids and a radial-interdigitated electrode. A black liquid is confined by a circular gasket with a donut shape. The surrounding of the black liquid is filled with an immiscible liquid. In the relaxing state, the black liquid obtains the largest clear aperture. By applying a voltage, the surface of the black liquid is stretched by the generated dielectric force, resulting in a reduction of its aperture. For the demonstrated iris, the diameter of the aperture can be changed from ?4.7??mm to ?1.2??mm when the voltage is applied from 0 to 70??V(rms). The aperture ratio is ?94%. Owing to the radial-interdigitated electrode, the aperture size of the iris can be effectively switched with a reasonably fast response time. The optical switch is polarization-insensitive. The potential applications of our iris are light shutters, optical attenuators, biomimicry, and wearable devices. PMID:25723444

  11. Liquid level detector

    DOEpatents

    Tshishiku, Eugene M. (Augusta, GA)

    2011-08-09

    A liquid level detector for conductive liquids for vertical installation in a tank, the detector having a probe positioned within a sheath and insulated therefrom by a seal so that the tip of the probe extends proximate to but not below the lower end of the sheath, the lower end terminating in a rim that is provided with notches, said lower end being tapered, the taper and notches preventing debris collection and bubble formation, said lower end when contacting liquid as it rises will form an airtight cavity defined by the liquid, the interior sheath wall, and the seal, the compression of air in the cavity preventing liquid from further entry into the sheath and contact with the seal. As a result, the liquid cannot deposit a film to form an electrical bridge across the seal.

  12. Monogroove liquid heat exchanger

    NASA Technical Reports Server (NTRS)

    Brown, Richard F. (Inventor); Edelstein, Fred (Inventor)

    1990-01-01

    A liquid supply control is disclosed for a heat transfer system which transports heat by liquid-vapor phase change of a working fluid. An assembly (10) of monogroove heat pipe legs (15) can be operated automatically as either heat acquisition devices or heat discharge sources. The liquid channels (27) of the heat pipe legs (15) are connected to a reservoir (35) which is filled and drained by respective filling and draining valves (30, 32). Information from liquid level sensors (50, 51) on the reservoir (35) is combined (60) with temperature information (55) from the liquid heat exchanger (12) and temperature information (56) from the assembly vapor conduit (42) to regulate filling and draining of the reservoir (35), so that the reservoir (35) in turn serves the liquid supply/drain needs of the heat pipe legs (15), on demand, by passive capillary action (20, 28).

  13. Liquid level sensor

    SciTech Connect

    Terhune, J. H.; Neissel, J. P.

    1985-06-04

    A liquid level detector, or detector array, for insertion into the pressure vessel of a nuclear reactor, or into any liquid-containing vessel, for that matter. A coaxial cable supports the detector, which includes a sensing element having a positive temperature-coefficient of electrical resistivity. The detector is driven by a constant current source of electricity and the presence of liquid is determined by making a resistance measurement.

  14. Liquid-Liquid Two-Phase Flow Systems Neima Brauner

    E-print Network

    Brauner, Neima

    2.22.2323 1 #12;Liquid-Liquid Two-Phase Flow Systems Neima Brauner School of Engineering, Tel-Aviv University Tel-Aviv 69978, Israel 1 General Description of Liquid-Liquid Flows: Flow Patterns Flows of two immiscible liquids are encountered in a diverse range of processes and equipments. In particular

  15. Checkliste: ERASMUS+, Dozentenmobilitt wei = Schritte des IO bzw. der ZUV orange = Schritte des/der Dozenten/-in

    E-print Network

    Meise, Reinhold

    Checkliste: ERASMUS+, Dozentenmobilität weiß = Schritte des IO bzw. der ZUV orange = Schritte des\\Dozentenmobilität\\Dozentenmobilität_STA_14_15\\Dozentenmobilität_Checkliste_2014_2015 Phasen wann?/ Frist was? wer? an wen? Formular, Dienstreisegenehmigung #12;Checkliste: ERASMUS+, Dozentenmobilität weiß = Schritte des IO bzw. der ZUV orange = Schritte

  16. Une unit motivante pour la mesure des aires : la fraise tagada ! Etude des rectangles de primtre 36 cm

    E-print Network

    Pansu, Pierre

    Une unité motivante pour la mesure des aires : la fraise tagada ! Etude des rectangles de périmètre plus grande aire. Etude des rectangles d'aire 36 cm² Propriété démontrée graphiquement : parmi tous les rectangles d'aire 36 cm², le carré est celui qui a le plus petit périmètre. Quadrilatères articulés Un défi

  17. Index des notations Certaines notations sont utilis'ees dans diff'erents domaines avec des significations dis

    E-print Network

    Ollivier, François

    le contexte des ensembles cract'eristiques) : p. 91. HC (C un ensemble de polynâ??omes diff'erentiels) : p. 93. AE C (C un ensemble de polynâ??omes diff'erentiels) : p. 93. C(`) (` un vecteur de paramIndex des notations Certaines notations sont utilis'ees dans diff'erents domaines avec des

  18. Liquid Metal Transformers

    E-print Network

    Lei Sheng; Jie Zhang; Jing Liu

    2014-01-30

    The room temperature liquid metal is quickly emerging as an important functional material in a variety of areas like chip cooling, 3D printing or printed electronics etc. With diverse capabilities in electrical, thermal and flowing behaviors, such fluid owns many intriguing properties that had never been anticipated before. Here, we show a group of unconventional phenomena occurring on the liquid metal objects. Through applying electrical field on the liquid metals immersed in water, a series of complex transformation behaviors such as self-assembling of a sheet of liquid metal film into a single sphere, quick mergences of separate metal droplets, controlled self-rotation and planar locomotion of liquid metal objects can be realized. Meanwhile, it was also found that two accompanying water vortexes were induced and reliably swirled near the rotating liquid metal sphere. Further, effects of the shape, size, voltage, orientation and geometries of the electrodes to control the liquid metal transformers were clarified. Such events are hard to achieve otherwise on rigid metal or conventional liquid spheres. This finding has both fundamental and practical significances which suggest a generalized way of making smart soft machine, collecting discrete metal fluids, as well as flexibly manipulating liquid metal objects including accompanying devices.

  19. Ultrasonic liquid level detector

    DOEpatents

    Kotz, Dennis M. (North Augusta, SC); Hinz, William R. (Augusta, GA)

    2010-09-28

    An ultrasonic liquid level detector for use within a shielded container, the detector being tubular in shape with a chamber at its lower end into which liquid from in the container may enter and exit, the chamber having an ultrasonic transmitter and receiver in its top wall and a reflector plate or target as its bottom wall whereby when liquid fills the chamber a complete medium is then present through which an ultrasonic wave may be transmitted and reflected from the target thus signaling that the liquid is at chamber level.

  20. Liquid Crystal Optofluidics

    SciTech Connect

    Vasdekis, Andreas E.; Cuennet, J. G.; Psaltis, D.

    2012-10-11

    By employing anisotropic fluids and namely liquid crystals, fluid flow becomes an additional degree of freedom in designing optofluidic devices. In this paper, we demonstrate optofluidic liquid crystal devices based on the direct flow of nematic liquid crystals in microfluidic channels. Contrary to previous reports, in the present embodiment we employ the effective phase delay acquired by light travelling through flowing liquid crystal, without analysing the polarisation state of the transmitted light. With this method, we demonstrate the variation in the diffraction pattern of an array of microfluidic channels acting as a grating. We also discuss our recent activities in integrating mechanical oscillators for on-chip peristaltic pumping.

  1. Liquid level detector

    DOEpatents

    Tokarz, Richard D. (West Richland, WA)

    1982-01-01

    A liquid level sensor having a pair of upright conductors spaced by an insulator defining a first high resistance path between the conductors. An electrically conductive path is interposed between the upright conductors at a discrete location at which liquid level is to be measured. It includes a liquid accessible gap of a dimension such that the electrical resistance across the conductor when the gap is filled with the liquid is detectably less than when the gap is emptied. The conductor might also be physically altered by temperature changes to serve also as an indicator of elevated temperature.

  2. Effets perturbateurs endocriniens des pesticides organochlores.

    PubMed

    Charlier, C; Plomteux, G

    2002-01-01

    Xenoestrogens such organochlorine pesticides are known to induce changes in reproductive development, function or behaviour in wildlife. Because these compounds are able to modify the estrogens metabolism, or to compete with estradiol for binding to the estrogen receptor, it may be possible that these products affect the risk of developing impaired fertility, precocious puberty or some kinds of cancer in man. Le plus ancien récit de lutte contre la pollution remonte à une légende indienne racontant que la divinité Sing-bonga était incommodée par les émanations des fours dans lesquels les Asuras fondaient leurs métaux (1). Evidemment depuis, la problématique n-a cessé de s-accroître et la contamination de la Terre par de nombreux polluants est devenue aujourd-hui un problème majeur de notre Société. La protection de notre environnement est une question capitale qui doit être respectée malgré la pression économique actuelle et qui ne cessera de croître au cours des prochaines années même si l-identification objective et indiscutable de ce qui est essentiel - donc devant être prioritairement garanti sur la planète - est difficile à cerner (2). « Un oiseau en mauvais état ne pond pas de bons oeufs » disait un proverbe grec. Mais ce n-est qu-à partir de la seconde moitié du XXème siècle que les toxicologues ont commencé à identifier les effets qu-avaient entraînés à l-échelle mondiale les pollutions émises aux XIXème siècle sur la faune sauvage et sur le cheptel (3). L-histoire contemporaine des pesticides industriels commence vers 1874 (synthèse des organochlorés) et se poursuit tout au long de ces 2 siècles en passant par la synthèse des organophosphorés (1950), des carbamates (1970) et des pyréthroïdes (1975) (4). Le dichlorodiphényltrichloroéthane (DDT) a été synthétisé pour la première fois par un étudiant en cours de préparation de sa thèse de doctorat : Othmer Zeidler. La production, reprise par les entreprises F.Mayo puis par la Geigy Co. a d-abord intéressé l-armée, puis l-agriculture. Dès la fin de la 2(ème) guerre mondiale, des mises en garde furent lancées à propos des effets nocifs du produit (4). Un déclin des populations de grives, d-aigles chauves, d-orfaies et de mammifères consommateurs de poissons fut constaté à partir des années 50 et dénoncé par Rachel Carson dans son célèbre appel du « Silent Spring » de 1962. Bien qu-il soit interdit en Occident depuis les années 70, ce produit a été tellement utilisé et présente une rémanence si longue qu-une contamination ubiquitaire existe aujourd-hui encore. De plus, ce produit continue à être produit aux USA pour être utilisé à des fins de démoustification dans les pays en voie de développement. Il en va de même de l-Hexachlorobenzène (HCB), un autre organochloré dont l-usage est interdit sous nos latitudes, mais reste fréquent dans d-autres pays. Ces deux exemples indiquent que le problème de la contamination continue à nous concerner, même pour des produits dont l-usage est aujourd-hui strictement réglementé ou interdit. Des effets sur la faune semblent encore actuellement devoir être attribués à ces produits. La diminution de la population des phoques dans la mer de Wadden pourrait être due à la forte contamination en composants organochlorés des poissons dont ces phoques se nourrissent (5). Exposé au DDT et à son métabolite dichlorodiphenyldichloroéthylène (DDE), le Seratherodon mossambicus présente une réduction de la sécrétion de cortisol par une action toxique cytospécifique sur l-axe hypothalamo-hypophysaire (6). Des travaux récents ont montré que le DDT et le DDE se lient chez les oiseaux et les mammifères au moyen de liaisons covalentes aux cellules de la zona fasciculata - homologue du tissu interrénal du poisson - induisant des microhémorragies. Cette « défaillance » cortisolique peut s-accompagner d-une perturbation du métabolisme glucidique et notamment d-un taux élevé de glycogène hépatique (7). Les pesticides organochlorés (

  3. Devenir des diplms Promotion 2009-2010

    E-print Network

    Sart, Remi

    de l'enquête. 66,4% occupent des fonctions cadres. Le salaire net mensuel moyen est de 1768 . Photo(s):©JérômePALL�-UniversitéBlaisePascal leur diplôme. Concernant les Masters de l'Université Blaise Pascal, les 908 diplômés de la promotion, une vue globalisée du devenir des diplômés de Master de l'Université Blaise Pascal, toutes spécialités

  4. Devenir des diplms Promotion 2010-2011

    E-print Network

    Sart, Remi

    de l'enquête. 74,6% occupent des fonctions cadres. Le salaire net mensuel moyen est de 1737 . Photo(s):©JérômePALL�-UniversitéBlaisePascal leur diplôme. Concernant les Masters de l'Université Blaise Pascal, les 1282 diplômés de la promotion, une vue globalisée du devenir des diplômés de Master de l'Université Blaise Pascal, toutes spécialités

  5. Une porte optique intensificatrice picoseconde a gain eleve: Caracterisation et application potentielle en imagerie de petits objets places dans des milieux diffusants

    NASA Astrophysics Data System (ADS)

    Marengo, Stephanie

    Dans cette etude, nous avons developpe un amplificateur a colorant possedant ces deux caracteristiques. Le colorant choisi, l'iodure de 3,3'-dimethyloxatricarbocyanine (methyl-DOTCI), possede un epaulement dans la bande d'absorption a 620 nm ce qui convient bien a notre pompe femtoseconde. De plus, son maximum de fluorescence est a 720 nm ce qui est particulierement interessant dans le cas des etudes avec des tissus biologiques humains. En effet, la fenetre dite "therapeutique" se situe dans les longueurs d'onde rouge et proche infrarouge. Le phenomene d'amplification, qui se produit dans des conditions experimentales precises, est en fait une emission stimulee du colorant qui est largement favorisee par rapport a sa fluorescence naturelle (emission spontanee). L'arrivee du signal incident, dont la longueur d'onde correspond au saut energetique entre l'etat fondamental et l'etat excite ou se trouvent les molecules, provoque une avalanche coherente de celles-ci vers l'etat fondamental generant ainsi l'emission stimulee. Une des conditions necessaires pour l'obtention d'un gain eleve est que la duree de l'impulsion de pompe soit inferieure au temps de relaxation des molecules ainsi qu'inferieure au temps requis pour effectuer un trajet dans la cellule de colorant. Ceci nous a permis d'amplifier un signal incident par un facteur entre 103 et 104. De plus, ce gain eleve n'est observe qu'a l'interieur d'une fenetre temporelle d'environ 10 picosecondes. Nous avons integre cet amplificateur a notre montage de transillumination afin d'acquerir des images d'un patron de lignes opaques immerge dans un milieu diffusant liquide. Des images de lignes ayant une resolution spatiale de 200 mum ont ete obtenues. La cible etait placee au centre d'un melange contenant des proportions variables de lait et d'eau. Deux longueurs de trajet optique dans la solution ont ete utilisees: 30 et 50 mm. Pour determiner les proprietes optiques de notre milieu diffusant, nous avons mis au point une technique de caracterisation basee sur la distribution radiale des photons transmis a travers le milieu. Deux parametres de transport, les coefficients de diffusion effectif (mus') et d'absorption (mu a), caracterisent la forme et l'amplitude du profil radial. Le fit des courbes experimentales a des courbes simulees nous a permis d'extraire ces coefficients. Les courbes simulees ont ete realisees grace a une simulation Monte Carlo qui incorpore les conditions experimentales de notre montage de caracterisation. (Abstract shortened by UMI.)

  6. Etude des etats electroniques en champ magnetique dans le niveau de Landau N=0 de la tricouche ABC de graphene

    NASA Astrophysics Data System (ADS)

    Rondeau, Maxime

    Dans cet ouvrage nous etudions les phases du gaz d'electrons bidimensionnel dans la tricouche de graphene en empilement ABC. En partant du modele des liaisons fortes et en faisant l'approximation du continuum autour des vallees K +, K-, nous obtenons un modele effectif a deux bandes qui permet de decrire la physique de basse energie des electrons en champ magnetique dans cette structure. Ce modele contient trois orbitales degenerees dans le niveau de Landau N = O. Ce dernier est donc 12N ?, fois degeneres en incluant les degres de liberte de spin et de vallee. En ajoutant l'interaction de Coulomb au systeme et en considerant seulement les remplissages v = -5, -4, -4, 5 afin d'avoir un systeme a trois niveaux, nous etudions le diagramme de phase du gaz d'electrons en fonction d'un biais electrique entre les couches externes. Nous trouvons une phase d'onde de densite de charge bidimensionnelle (ODC2D) comme etat fondamental du systeme. Cette ODC2D se nomme cristal dans ce memoire et nous derivons ses proprietes de transports et ses modes collectifs. Nous discutons egalement du caractere topologique de ce cristal. Notre etude englobe aussi les phases liquides avec ou sans coherence orbitale. Nous concluons notre memoire par l'etude de quelques signatures experimentales des phases du gaz d'electrons dans la tricouche.

  7. Rpertoire des emplois au 1er dcembre 2012 Des diplms de Master 2010

    E-print Network

    Jeanjean, Louis

    selon la nomenclature de l'INSEE · Le type de contrat · Le salaire en euros · Le type d'employeur · L management administratif et financier (CTU, IAE) - Management, spécialité management des relations humaines

  8. 86419 -Stage-Caractrisation des dimensions des filaments de cellulose (FC)

    E-print Network

    Leclercq, Remi

    concevoir une méthode pour mesurer directement les dimensions des FC et d'étudier les relations entre les(s) linguistique(s) : Français parlé. Anglais parlé. Français écrit. #12;Anglais écrit. Autre(s) exigence

  9. Scalability of mass transfer in liquid-liquid flow

    E-print Network

    Woitalka, A.

    We address liquid–liquid mass transfer between immiscible liquids using the system 1-butanol and water, with succinic acid as the mass transfer component. Using this system we evaluate the influence of two-phase flow ...

  10. Influence des défauts de la structure du verre sur la résistance mécanique des fibres optiques

    NASA Astrophysics Data System (ADS)

    Chmel, A.; Baptizmanski, V. V.; Kharshak, A. A.

    1992-12-01

    For silica (pure and doped) optical fibers prepared from preforms irradiated by thermal neutrons and Ar^+ ions, the measurements of lifetime under transverse stress were carried out. It is found that the neutron bombardment leads to decrease of the lifetime and the strength of fiber while the ion implantation results in increasing of these parameters. The influence of particle irradiation on the glass strength is explained by the generation of structural defects which were observed by the infrared an Raman spectroscopy methods. The direction of the change of mechanical properties of fibers is determined by the type of defects and their distribution in the cross-section of fiber. Des préformes de fibres optiques de silice ont été exposées à un bombardement par des faisceaux de neutrons thermiques et d'ions Ar^+ à énergie de 40 keV afin d'engendrer des défauts de la structure respectivement dans le volume ou dans la couche superficielle des échantillons. Les fibres obtenues des préformes irradiées et non irradiées ont été mises en charge de flexion. On a déterminé leur temps de rupture sous diverses contraintes de traction sur la surface extérieure de la fibre en flexion. On a observé une diminution du temps de rupture des fibres après le bombardement neutronique et une augmentation après l'implantation ionique. L'analyse de la nature des défauts en faisant appel à la spectroscopie infrarouge et Raman a fait ressortir que l'irradiation aux ions entraînait essentiellement des liaisons chimiques dans une fine couche superficielle de l'échantillon alors que l'irradiation aux neutrons occasionnait une déformation des zones du réseau silicique dans toute la section de la préforme et de la fibre. L'amélioration de la résistance mécanique s'explique par une augmentation de la mobilité des éléments structuraux de la matrice de verre par suite d'une rupture partielle des liaisons chimiques et sa diminution par l'apparition de concentrateurs supplémentaires de contraintes à l'échelle moléculaire.

  11. Quantification des besoins en intrants antipaludiques: contribution à l'actualisation des hypothèses pour la quantification des intrants de prise en charge des cas de paludisme grave en République Démocratique du Congo

    PubMed Central

    Likwela, Joris Losimba; Otokoye, John Otshudiema

    2015-01-01

    Les formes graves de paludisme à Plasmodium falciparum sont une cause majeure de décès des enfants de moins de 5 ans en Afrique Sub-saharienne. Un traitement rapide dépend de la disponibilité de médicaments appropriés au niveau des points de prestation de service. La fréquence des ruptures de stock des commodités antipaludiques, en particuliers celles utilisées pour le paludisme grave, avait nécessité une mise à jour des hypothèses de quantification. Les données issues de la collecte de routine du PNLP de 2007 à 2012 ont été comparées à celles rapportés par d'autres pays africains et utilisées pour orienter les discussions au cours d'un atelier organisé par le PNLP et ses partenaires techniques et financiers afin de dégager un consensus national. La proportion des cas de paludisme rapportés comme grave en RDC est resté autour d'une médiane de 7% avec un domaine de variation de 6 à 9%. Hormis la proportion rapportée au Kenya (2%), les pays africains ont rapporté une proportion de cas grave variant entre 5 et 7%. Il apparaît que la proportion de 1% précédemment utilisée pour la quantification en RDC a été sous-estimée dans le contexte de la gestion des cas graves sur terrain. Un consensus s'est dégagé autour de la proportion de 5% étant entendu que des efforts de renforcement des capacités seraient déployés afin d'améliorer le diagnostic au niveau des points de prestation des services. PMID:26213595

  12. Opération multimode transverse des OPOs: des structures classiques aux corrélations quantiques

    NASA Astrophysics Data System (ADS)

    Martinelli, M.; Ducci, S.; Gigan, S.; Treps, N.; Maître, A.; Fabre, C.

    2002-06-01

    Nous démontrons la formation de structures transverses sur les faisceaux émis par un oscillateur paramétrique optique (OPO) de type II en configuration confocale. D'un point de vue classique nous mettons en évidence le caractère multimode transverse de telles structures. A travers l'étude des corrélations spatiales des faisceaux générés nous montrons que ces structures sont également multimodes d'un point de vue quantique.

  13. Interaction des ions phosphate in vitro avec des particules inhalables d'oxyde de cerium

    NASA Astrophysics Data System (ADS)

    Matton, S.; Massiot, P.; Fritsch, P.

    1998-04-01

    Methods have been developed to quantify phosphorus in vitro adsorption on inhalable CeO2 particles. Two assays are potentially useful: adsorption measurement of 32P and X-ray spectrometry. Des méthodes in vitro pour quantifier l'adsorption du phosphore sur des particules inhalables de CeO2 ont été développées. Deux tests s'avèrent utilisables : la mesure de l'adsorption du 32P et la spectrométrie X.

  14. Etat des lieux des mycobactérioses atypiques au Burkina Faso: résultats d'une enquête régionale

    PubMed Central

    Zida, Sylvie; Tarnagda, Zékiba; Kaboré, Antoinette; Zingué, Dézémon; Hien, Hervé; Sanou, Adama; Michel Gomgnimbou, Kireopori; Nouctara, Moumini; Ouédraogo, Mamoudou; Ouédraogo, Oumarou; Godreuil, Sylvain; Méda, Nicolas

    2014-01-01

    Introduction L’étude avait pour but de déterminer la fréquence d'isolement des mycobactéries atypiques chez les patients déclarés tuberculeux pulmonaire à microscopie positive (TPM+) au Burkina Faso. Méthodes Il s'est agit d'une étude transversale qui s'est déroulée de mars 2011 à février 2012. Les patients TPM+ de plus de 15 ans ont été inclus dans l’étude de manière systématique dans les centres de diagnostic et de traitement (CDT) de la région sanitaire des Hauts Bassins. Une culture des mycobactéries et une identification biochimique ont été réalisées sur les échantillons des patients TPM+ La sérologie VIH a été réalisée par des tests rapides. Résultats Une fréquence de 11% (8/73) de mycobactéries atypiques et 89,0% (65/73) de mycobactéries du complexe tuberculosis ont été identifiées des 73 patients TPM+ inclus dans l’étude. La tranche d’âge de 20 à 40 ans était la plus touchée par les mycobactérioses en général et constituait 48% de l’échantillon. Nous avons trouvé 12,2% (8 / 66) de patients VIH positif, 83,3% (55 / 66) de patients VIH négatif et 4,5% (3 / 66) de patients dont le statut VIH était indéterminé. Conclusion Notre étude a mis en lumière l'implication des mycobactéries atypiques dans la pathogénie de certains patients déclarés TPM+. Le rôle des mycobactéries atypiques dans les infections pulmonaires est probablement sous estimé et devra être examiné avec plus de détails et sur un échantillon plus grand. PMID:25396014

  15. Traitement des fractures des plateaux externes par vissage percutané assisté par arthroscopie

    PubMed Central

    Abouchane, Merouane; Belmoubarik, Amine; Benameur, Hamza; Haddoun, Ahmed Reda; Nechad, Mohammed

    2015-01-01

    Le but de notre étude est d'évaluer les résultats de fractures des plateaux tibiaux externes traitées par ostéosynthèse percutanée assistée par arthroscopie. Dix patients (8 hommes et 2 femmes) de 32 ans en moyenne ont subi cette intervention afin de réparer des fractures des plateaux tibiaux Schatzker I-III. Après avoir appliqué un garrot pneumatique, nous avons réduit et fixé la fracture au moyen de vis cannelées souschondrales. Lésions associées retrouvent deux lésions partielles du ménisque externe ont été retrouvé, traitées par résection partielle. Une orthèse de genou été de mise à but antalgique et protectrice pendant six semaines avec béquillage et interdiction de l'appui pour une durée de douze semaines avec reprise d'appui partiel au delà. La durée d'hospitalisation été d'une moyenne de cinq jours. La rééducation passive a été commence le lendemain de l'intervention et continuait dans chez un kinésithérapeute à la sortie du patient du service. Le suivi été à J7, J15, 1mois, 3mois, 6 mois puis tous les 6 mois. Neuf de nos patients ont été revu régulièrement sauf un perdu de vue. Le recul moyen de notre série été de 16 mois (10 et 24 mois). Le score de Lysholm a été utilisé pour évaluer les résultats cliniques chez nos neuf patients: excellent chez trois patients bons chez trois moyen chez un seul et mauvais chez deux patients. Tous nos neuf patients ont consolidé (figure 10 contrôle scopique d un article). Aucune gonarthrose n'a été note chez nos neuf patients due essentiellement au recul moyen faible de 16 mois. Le traitement des fractures des plateaux tibiaux externes assisté par arthroscopie produit des résultats satisfaisants et peut être accepté comme solution de rechange efficace au traitement des fractures des plateaux tibiaux causées par un choc de faible énergie. PMID:26587137

  16. Dépistage des maladies cardiovasculaires chez des étudiants de l'Université de Douala et influence des activités physiques et sportives

    PubMed Central

    Ewane, Marielle Epacka; Mandengue, Samuel Honoré; Priso, Eugene Belle; Tamba, Stéphane Moumbe; Ahmadou; Fouda, André Bita

    2012-01-01

    Introduction Les maladies cardiovasculaires (MCV) constituent l'une des principales causes de mortalité dans les pays en développement. Le dépistage de ces dernières chez des jeunes est un défi dans la lutte contre leur expansion. Le but de cette étude était de dépister ces maladies au sein d'une population jeunes d’étudiants camerounais. Methodes Deux mille six cent cinquante-huit étudiants de l'Université de Douala (23,6 ± 2,9 ans, sex-ratio H/F = 0,9) ont en Avril - Mai 2011 participé à une campagne de dépistage gratuit du diabète, de l'hypertension artérielle (HTA) et de l'obésité. Ils ont également été soumis à une d'enquête évaluant leur niveau en activités physiques et sportives (APS). Resultats 12,7% des participants avaient une pression artérielle (PA) ? 140/90 mmHg, 3,6% étaient obèses et 0,9% avaient une glycémie ?1,26 g/L. Des corrélations ont été trouvées entre certains facteurs de risque (diabète, hypertension et obésité) et le niveau académique d'une part (r =0,366; p < 0,0001) et le temps passé devant la télévision d'autres part (r = 0,411; p < 0,0001). L‘APS était inversement corrélée à l‘âge (r =-0,015; p < 0,0001) et au temps passé devant la télévision (r = -0,059; p = 0,002). Conclusion La présence des MCV et leurs facteurs de risque mis en évidence dans cette étude réalisée en milieu estudiantin camerounais interpelle à une prévention et une éducation dans la lutte contre ces dernières. PMID:22655111

  17. Contrôle du marché informel à l’heure de la mondialisation des échanges. Le cas des antirétroviraux au Chili

    PubMed Central

    Brousselle, Astrid; Morales, Cristián

    2013-01-01

    Résumé Les nouveaux médicaments pour le VIH/sida ont créé des besoins d’accessibilité aux traitements que les gouvernements n’ont pas toujours réussi à couvrir. Il en résulte l’émergence d’un marché informel des ARV. Par l’analyse de la situation au Chili, nous traitons des différents créneaux d’approvisionnement, des conséquences de l’existence d’un tel marché, ainsi que des moyens envisageables pour réduire les effets indésirables. Les aspects tant microéconomiques que macroéconomiques concernant le marché et l’accessibilité aux médicaments sont abordés. PMID:23997580

  18. Liquid Chromatography in 1982.

    ERIC Educational Resources Information Center

    Freeman, David H.

    1982-01-01

    Reviews trends in liquid chromatography including apparatus, factors affecting efficient separation of a mixture (peak sharpness and speed), simplified problem-solving, adsorption, bonded phase chromatography, ion selectivity, and size exclusion. The current trend is to control chemical selectivity by the liquid phase. (Author/JN)

  19. Advanced proteomic liquid chromatography

    SciTech Connect

    Xie, Fang; Smith, Richard D.; Shen, Yufeng

    2012-10-26

    Liquid chromatography coupled with mass spectrometry is the predominant platform used to analyze proteomics samples consisting of large numbers of proteins and their proteolytic products (e.g., truncated polypeptides) and spanning a wide range of relative concentrations. This review provides an overview of advanced capillary liquid chromatography techniques and methodologies that greatly improve separation resolving power and proteomics analysis coverage, sensitivity, and throughput.

  20. Synthesis of ionic liquids

    DOEpatents

    Dai, Sheng [Knoxville, TN; Luo, Huimin [Knoxville, TN

    2008-09-09

    Ionic compounds which are liquids at room temperature are formed by the method of mixing a neutral organic liqand with the salt of a metal cation and its conjugate anion. The liquids are hydrophobic, conductive and stable and have uses as solvents and in electrochemical devices.

  1. Column Liquid Chromatography.

    ERIC Educational Resources Information Center

    Majors, Ronald E.; And Others

    1984-01-01

    Reviews literature covering developments of column liquid chromatography during 1982-83. Areas considered include: books and reviews; general theory; columns; instrumentation; detectors; automation and data handling; multidimensional chromatographic and column switching techniques; liquid-solid chromatography; normal bonded-phase, reversed-phase,…

  2. Guidance Document Cryogenic Liquids

    E-print Network

    have boiling points below -73°C (-100°F). The most common cryogenic liquids currently on campus conditions of temperature and pressure. But all have two very important properties in common. First, the liquids and their vapors are extremely cold. The risk of destructive freezing of tissues is always present

  3. Liquid heat capacity lasers

    DOEpatents

    Comaskey, Brian J. (Walnut Creek, CA); Scheibner, Karl F. (Tracy, CA); Ault, Earl R. (Livermore, CA)

    2007-05-01

    The heat capacity laser concept is extended to systems in which the heat capacity lasing media is a liquid. The laser active liquid is circulated from a reservoir (where the bulk of the media and hence waste heat resides) through a channel so configured for both optical pumping of the media for gain and for light amplification from the resulting gain.

  4. INEEL Liquid Effluent Inventory

    SciTech Connect

    Major, C.A.

    1997-06-01

    The INEEL contractors and their associated facilities are required to identify all liquid effluent discharges that may impact the environment at the INEEL. This liquid effluent information is then placed in the Liquid Effluent Inventory (LEI) database, which is maintained by the INEEL prime contractor. The purpose of the LEI is to identify and maintain a current listing of all liquid effluent discharge points and to identify which discharges are subject to federal, state, or local permitting or reporting requirements and DOE order requirements. Initial characterization, which represents most of the INEEL liquid effluents, has been performed, and additional characterization may be required in the future to meet regulations. LEI information is made available to persons responsible for or concerned with INEEL compliance with liquid effluent permitting or reporting requirements, such as the National Pollutant Discharge Elimination System, Wastewater Land Application, Storm Water Pollution Prevention, Spill Prevention Control and Countermeasures, and Industrial Wastewater Pretreatment. The State of Idaho Environmental Oversight and Monitoring Program also needs the information for tracking liquid effluent discharges at the INEEL. The information provides a baseline from which future liquid discharges can be identified, characterized, and regulated, if appropriate. The review covered new and removed buildings/structures, buildings/structures which most likely had new, relocated, or removed LEI discharge points, and at least 10% of the remaining discharge points.

  5. Precision liquid level sensor

    DOEpatents

    Field, Michael E. (Albuquerque, NM); Sullivan, William H. (Albuquerque, NM)

    1985-01-01

    A precision liquid level sensor utilizes a balanced R. F. bridge, each arm including an air dielectric line. Changes in liquid level along one air dielectric line imbalance the bridge and create a voltage which is directly measurable across the bridge.

  6. LIGHT NONAQUEOUS PHASE LIQUIDS

    EPA Science Inventory

    Nonaqueous phase liquids (NAPLS) are hydrocarbons that exist as a separate, immiscible phase when in contact with water and/or air. ifferences in the physical and chemical properties of water and NAPL result in the formation of a physical interface between the liquids which preve...

  7. Synthesis of ionic liquids

    SciTech Connect

    Dai, Sheng; Luo, Huimin

    2011-11-01

    Ionic compounds which are liquids at room temperature are formed by the method of mixing a neutral organic ligand with the salt of a metal cation and its conjugate anion. The liquids are hydrophobic, conductive and stable and have uses as solvents and in electrochemical devices.

  8. Precision liquid level sensor

    DOEpatents

    Field, M.E.; Sullivan, W.H.

    1985-01-29

    A precision liquid level sensor utilizes a balanced R. F. bridge, each arm including an air dielectric line. Changes in liquid level along one air dielectric line imbalance the bridge and create a voltage which is directly measurable across the bridge. 2 figs.

  9. Comprendre la maltraitance des aînés en pratique familiale

    PubMed Central

    Yaffe, Mark J.; Tazkarji, Bachir

    2012-01-01

    Résumé Objectif Présenter ce qui constitue la maltraitance des aînés, ce dont les médecins de famille devraient être au courant, les signes et les symptômes laissant présager de mauvais traitements chez des adultes plus âgés, comment l’outil Elder Abuse Suspicion Index peut aider à détecter la maltraitance et les options qui existent pour réagir en cas de soupçons de maltraitance. Sources des données On a fait une recension dans MEDLINE, PsycINFO et Social Work Abstracts pour trouver des publications en français ou en anglais, de 1970 à 2011, à l’aide des expressions elder abuse, elder neglect, elder mistreatment, seniors, older adults, violence, identification, detection tools et signs and symptoms. Les publications pertinentes ont fait l’objet d’un examen. Message principal La maltraitance des aînés est une cause importante de morbidité et de mortalité chez les adultes plus âgés. Si les médecins de famille sont bien placés pour détecter des mauvais traitements infligés aux aînés, leurs taux réels de signalement de cas de maltraitance sont plus faibles que dans d’autres professions. Cette situation pourrait s’améliorer s’ils comprenaient mieux les genres d’agissements qui constituent de la maltraitance des aînés, ainsi que les signes et les symptômes observés au bureau qui pourraient pointer vers des cas de mauvais traitements. La détection de tels cas pourrait être facilitée par le recours à un court outil validé, comme l’Elder Abuse Suspicion Index. Conclusion Les médecins de famille peuvent jouer un rôle plus important dans la détection d’une éventuelle maltraitance des aînés. Une fois qu’on soupçonne de mauvais traitements, il existe dans la plupart des communautés des services sociaux ou des forces de l’ordre accessibles pour effectuer des évaluations plus approfondies et intervenir.

  10. Effets des electrons secondaires sur l'ADN

    NASA Astrophysics Data System (ADS)

    Boudaiffa, Badia

    Les interactions des electrons de basse energie (EBE) representent un element important en sciences des radiations, particulierement, les sequences se produisant immediatement apres l'interaction de la radiation ionisante avec le milieu biologique. Il est bien connu que lorsque ces radiations deposent leur energie dans la cellule, elles produisent un grand nombre d'electrons secondaires (4 x 104/MeV), qui sont crees le long de la trace avec des energies cinetiques initiales bien inferieures a 20 eV. Cependant, il n'y a jamais eu de mesures directes demontrant l'interaction de ces electrons de tres basse energie avec l'ADN, du principalement aux difficultes experimentales imposees par la complexite du milieu biologique. Dans notre laboratoire, les dernieres annees ont ete consacrees a l'etude des phenomenes fondamentaux induits par impact des EBE sur differentes molecules simples (e.g., N2, CO, O2, H2O, NO, C2H 4, C6H6, C2H12) et quelques molecules complexes dans leur phase solide. D'autres travaux effectues recemment sur des bases de l'ADN et des oligonucleotides ont montre que les EBE produisent des bris moleculaires sur les biomolecules. Ces travaux nous ont permis d'elaborer des techniques pour mettre en evidence et comprendre les interactions fondamentales des EBE avec des molecules d'interet biologique, afin d'atteindre notre objectif majeur d'etudier l'effet direct de ces particules sur la molecule d'ADN. Les techniques de sciences des surfaces developpees et utilisees dans les etudes precitees peuvent etre etendues et combinees avec des methodes classiques de biologie pour etudier les dommages de l'ADN induits par l'impact des EBE. Nos experiences ont montre l'efficacite des electrons de 3--20 eV a induire des coupures simple et double brins dans l'ADN. Pour des energies inferieures a 15 eV, ces coupures sont induites par la localisation temporaire d'un electron sur une unite moleculaire de l'ADN, ce qui engendre la formation d'un ion negatif transitoire dans un etat electronique dissociatif, cette localisation est suivie d'une fragmentation. A plus haute energie, la dissociation dipolaire (i.e., la formation simultanee d'un ion positif et negatif) et l'ionisation jouent un role important dans le dommage de l'ADN. L'ensemble de nos resultats permet d'expliquer les mecanismes de degradation de l'ADN par les EBE et d'obtenir des sections efficaces effectives des differents types de dommages.

  11. Liquid metal enabled pump

    PubMed Central

    Tang, Shi-Yang; Khoshmanesh, Khashayar; Sivan, Vijay; Petersen, Phred; O’Mullane, Anthony P.; Abbott, Derek; Mitchell, Arnan; Kalantar-zadeh, Kourosh

    2014-01-01

    Small-scale pumps will be the heartbeat of many future micro/nanoscale platforms. However, the integration of small-scale pumps is presently hampered by limited flow rate with respect to the input power, and their rather complicated fabrication processes. These issues arise as many conventional pumping effects require intricate moving elements. Here, we demonstrate a system that we call the liquid metal enabled pump, for driving a range of liquids without mechanical moving parts, upon the application of modest electric field. This pump incorporates a droplet of liquid metal, which induces liquid flow at high flow rates, yet with exceptionally low power consumption by electrowetting/deelectrowetting at the metal surface. We present theory explaining this pumping mechanism and show that the operation is fundamentally different from other existing pumps. The presented liquid metal enabled pump is both efficient and simple, and thus has the potential to fundamentally advance the field of microfluidics. PMID:24550485

  12. Reprsentation des connaissances Traitement du langage naturel

    E-print Network

    Turenne, Nicolas

    items lexicaux ambigus. Si vous ne percevez pas l'ambiguïté, pensez à ('time flies' analogue à 'fruit de ce phénomène, tels que 'Times flies like an arrow', où 'time', 'flies' et 'like' sont tous des flies'. Une forme probablement plus ennuyeuse d'ambiguïté est connue sous le nom d' ambiguïté d

  13. L'exploitation des populations naturelles

    E-print Network

    Blouin-Demers, Gabriel

    ;Tragedy of the commons Les décisions sont prises par des individus... #12;· La simplicité de l est K/2 K K/2 rK/4 #12;Journal of the Fisheries Research Board of Canada (1967) 24: 145-190 #12;Modèle jeunes poissons en fonction d'un index de population de morue Journal of the Fisheries Research Board

  14. La dysplasie fibreuse: état des lieux

    PubMed Central

    Akasbi, Nessrine; Abourazzak, Fatima Ezzahra; Talbi, Sofia; Tahiri, Latifa; Harzy, Taoufik

    2015-01-01

    La dysplasie fibreuse des os est une affection osseuse bénigne congénitale mais non héréditaire, où l'os normal est remplacé par un tissu fibreux renfermant une ostéogenèse immature. Elle est due à une mutation du gène GNAS 1sur le chromosome 20q13, une mutation activatrice de la sous-unité ? de la protéine G. C'est une pathologie qui est le plus souvent silencieuse, de découverte fortuite sur une radiographie standard ou révélée par une douleur osseuse ou une fracture pathologique. L'imagerie et l'histologie, quand elle est nécessaire, permettent d’établir le diagnostic. Bien qu'il ne s'agisse pas d'une tumeur, elle est souvent classée dans la catégorie des tumeurs osseuses bénignes pour des raisons de diagnostic différentiel radiographique et anatomopathologique. Elle peut être monostotique ou polyostotique. L'approche thérapeutique est essentiellement symptomatique. Quelques publications récentes ont suggéré l'intérêt majeur d'un bisphosphonate, en particulier le pamidronate, qui diminuerait les douleurs et stimulerait une reminéralisation progressive des zones ostéolytiques chez les patients traités. D'autres traitements tels que la thérapie ciblée sont en cours d’évaluation. PMID:26401215

  15. Mechanik des Grun Fluoreszierenden Hendrik Dietz

    E-print Network

    Dietz, Hendrik

    .3 Wildtype-GFP und Cycle3-GFP . . . . . . . . . . . . . . . . . . . . . . . . 5 2.4 Fluoreszenz als Indikator des nativen GFP . . . . . . . . . . . . . . . . . . 6 3 Theoretische Grundlagen 9 3.1 Elastizit¨at von-Carlo Simulationen . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 5 Ig8-GFP und DdFLN(1-5)-GFP 27 5

  16. The "Conservatoire National des Arts et Metiers"

    ERIC Educational Resources Information Center

    Kuhn, Gerard

    2004-01-01

    The overall mission of the Conservatoire national des arts et metiers--(CNAM) [National Conservatory of Industrial Arts and Trades] is outlined. One of its centers, the "Centre national de l'entrepreneuriat"--(CNE) [National Center for Entrepreneurship] is described in greater detail. In particular, this center offers various services, notably…

  17. Etats financiers 2008 Table des matires

    E-print Network

    Halazonetis, Thanos

    supplémentaires du personnel administratif et technique 13 2.19. Fonds alloués par des tiers 13 2.20. Contrats de.2. Détention d'actif dans la société CIBM 23 20.3. Contrats de location 23 20.4. Contrats de leasing 23 21

  18. Bibliothque cole des Ponts ParisTech

    E-print Network

    Ghorbel, Amin

    mécanique et matériaux [ La Bibliothèque propose aux étudiants des espaces pour travailler seul ou en groupe://bibliotheque.enpc.fr Les espaces de travail Une équipe de documentalistes Les ressources pédagogiques #12;. Trois salles de travail en groupe peuvent être réservées à l'accueil de la bibliothèque. Chacune est

  19. Bibliothque cole des Ponts ParisTech

    E-print Network

    Ghorbel, Amin

    mécanique et matériaux [ La Bibliothèque propose aux étudiants des espaces pour travailler seul ou en groupe://bibliotheque.enpc.fr Les espaces de travail Une équipe de documentalistes Les ressources pédagogiques Vivien Girard Travaux. Quatre espaces projet peuvent être réservés à l'accueil de la bibliothèque. Chacun est équipé d'un écran

  20. Studienordnung des Masterstudiengangs ,,Health Care Management"

    E-print Network

    Greifswald, Ernst-Moritz-Arndt-Universität

    1 Studienordnung des Masterstudiengangs ,,Health Care Management" an der Ernst-Moritz-Arndt-Universität Greifswald die folgende Studienordnung für den Masterstudiengang ,,Health Care Management" als Satzung Master- studiengang (M.Sc.) ,,Health Care Management" an der Ernst-Moritz-Arndt-Universität Greifswald

  1. Studienordnung des Masterstudiengangs ,,Health Care Management"

    E-print Network

    Greifswald, Ernst-Moritz-Arndt-Universität

    Studienordnung des Masterstudiengangs ,,Health Care Management" an der Ernst-Moritz-Arndt-Universität Greifswald die fol- gende Studienordnung für den Masterstudiengang ,,Health Care Manage- ment" als Satzung Masterstudiengang (M.Sc.) ,,Health Care Management" an der Ernst-Moritz- Arndt-Universität Greifswald vom 15. März

  2. La conservation des phoques gris (Halichoerus grypus)

    E-print Network

    Blouin-Demers, Gabriel

    » · Pollution ­ Dégradation et perte d'habitat · Exploitation des ressources marines ­ Energie renouvelable Protection Act » de 1972 · Chasse interdite en 1987 (Pêche et Océan Canada) #12;Energie renouvelable marine (Exemple de l'Irlande) Marine Policy 35 (2011) 748­755 #12;Energie renouvelable marine #12;Pêches

  3. Modélisation macroscopique des milieux stratifiés conducteurs

    NASA Astrophysics Data System (ADS)

    Matagne, E.; Conard, J. Ph.

    1997-11-01

    Many laminated structures are recognised in Electrotechnics : magnetic cores, flat conductors windings, slotted surfaces... These structures exhibit macroscopic properties, as magnetic than electric ones. This paper shows how these characteristics can be obtained by homogenisation. It deals with linear materials but taking into account the effect of eddy currents, as well on the macroscopic magnetic permeability as on the macroscopic electric conductivity, which become then complex numbers. An example of use of the macroscopic properties is provided. On peut identifier en électrotechnique de nombreuses structures stratifiées: noyaux magnétiques, bobinages formés de conducteurs plats, surfaces encochées... Ces structures présentent des propriétés macroscopiques tant magnétiques qu'électriques. Cet article montre comment ces caractéristiques peuvent être obtenues par homogénéisation. Il se limite au cas de matériaux linéaires mais en prenant en compte l'effet des courants de Foucault aussi bien sur la perméabilité magnétique macroscopique que sur la conductivité électrique macroscopique, grandeurs qui deviennent alors des nombres complexes. Un exemple d'utilisation des caractéristiques macroscopiques est fourni.

  4. Le cynisme des chiens Jacky Dahomay.

    E-print Network

    Blondel, Corinne - Institut de Mathématiques de Jussieu, Université Paris 7

    'a littéralement bouleversé. Et j'ai pleuré. De rage bien entendu. Je suis un vieil enseignant, à la veille de la'indignation. Toutefois, des chiens, préservons-nous de leur rage et de leur cynisme. J'emprunte cette expression « le

  5. More About Spurious Numerical Solutions Of DEs

    NASA Technical Reports Server (NTRS)

    Yee, H. C.; Sweby, P. K.

    1995-01-01

    Paper discusses reliability of time-dependent approach to numerical solution of nonlinear differential equations (DEs) that describe steady-state behaviors of physical systems. Time-dependent approach followed in related study described in "Spurious Numerical Solutions of Differential Equations" (ARC-13209).

  6. 06seleccin de contenidos DES-IGUALES

    E-print Network

    Fernández Pascual, Ricardo

    06selección de contenidos IGUALDAD DES-IGUALES Laura Arroyo LA RESPUESTA PATRIARCAL A LA CRISIS: UN NUEVO TIMO A LAS MUJERES Laura Nuño DESIGUALDADES POR GÉNERO Y EDAD. LA DOBLE DESIGUALDAD DE LAS MUJERES. Universidad Rey Juan Carlos. Desigualdades por género y edad. La doble desigualdad de las mujeres jóvenes

  7. Etudes physiques des mélanges eau-cryoprotecteurs

    NASA Astrophysics Data System (ADS)

    Vassoille, R.; Perez, J.

    The aim of the following review is to present the most important studies concerning the physical properties of water-solutes mixtures used in cryobiology. Cryobiology is a branch of biology which deals with the very low temperature behaviour of cells. This technique is developed today in several directions. The creation of banks of cells and perhaps in a short time of small organs, is the purpose of much research in this domain. Before freezing, living cells are generally put in a solution containing one or more solutes. The role of these solutes is to protect the cells against damage due to crystallization of water (cryoprotectors). The mechanisms of cryoprotection are not well known ; nevertheless the vitreous state formation during cooling is often invoked. So, it is possible to avoid crystallization damage such as mechanical strain (due to an increase of volume of about 10 %) and salt effects (due to osmotic pressure). The conditions in which the vitreous state is obtained, maintained during cooling, storage at low temperature and rewarming can be defined by physical studies presented in the following review. Le présent travail est essentiellement une revue bibliographique des principales études physiques qui ont été réalisées avec des solutions de composés habituellement employés en cryobiologie. La cryobiologie est une branche de la biologie qui s'intéresse au comportement des cellules à basse température. Cette discipline est actuellement en plein développement dans des domaines très divers. Son principal but est la création de banques de cellules de plus en plus complexes avec comme perspective la conservation des organes. Les cellules vivantes sont généralement placées avant congélation dans une solution contenant divers composés dont le rôle est de protéger les cellules contre les effets de la cristallisation de l'eau. L'action protectrice de ces cryoprotecteurs est encore mal connue; cependant, la formation d'un état vitreux lors du refroidissement est souvent invoquée. Ainsi, il est possible d'éviter les dommages liés à la cristallisation : contrainte mécanique due à l'augmentation de volume, effets de sel dus à l'existence d'un gradient de pression osmotique de part et d'autre de la membrane cellulaire. Les conditions d'obtention et de maintien de cet état vitreux lors des opérations de congélation peuvent être définies par des études physiques dont nous proposons une revue.

  8. Noncavitating Pump For Liquid Helium

    NASA Technical Reports Server (NTRS)

    Hasenbein, Robert; Izenson, Michael; Swift, Walter; Sixsmith, Herbert

    1996-01-01

    Immersion pump features high efficiency in cryogenic service. Simple and reliable centrifugal pump transfers liquid helium with mass-transfer efficiency of 99 percent. Liquid helium drawn into pump by helical inducer, which pressurizes helium slightly to prevent cavitation when liquid enters impeller. Impeller then pressurizes liquid. Purpose of pump to transfer liquid helium from supply to receiver vessel, or to provide liquid helium flow for testing and experimentation.

  9. Des recommandations probantes pour surveiller l’innocuité des antipsychotiques de deuxième génération chez les enfants et les adolescents

    PubMed Central

    Pringsheim, Tamara; Panagiotopoulos, Constadina; Davidson, Jana; Ho, Josephine

    2012-01-01

    HISTORIQUE : Au Canada, l’utilisation d’antipsychotiques, notamment les antipsychotiques de deuxième génération (ADG), a augmenté de façon considérable depuis cinq ans chez les enfants ayant des troubles de santé mentale. Ces médicaments ont le potentiel de causer de graves complications métaboliques et neurologiques lorsqu’on les utilise de manière chronique. OBJECTIF : Synthétiser les données probantes relatives aux effets secondaires métaboliques et neurologiques précis associés à l’usage d’ADG chez les enfants et fournir des recommandations probantes sur la surveillance de ces effets secondaires. MÉTHODOLOGIE : Les auteurs ont procédé à une analyse systématique des essais cliniques contrôlés des ADG auprès d’enfants. Ils ont fait des recommandations à l’égard de la surveillance de l’innocuité des ADG d’après un modèle de classification fondé sur le système GRADE (système de notation de l’évaluation et de l’élaboration des recommandations). Lorsque les données probantes n’étaient pas suffisantes, ils fondaient leurs recommandations sur le consensus et l’avis d’experts. Un groupe consensuel multidisciplinaire a analysé toutes les données probantes pertinentes et est parvenu à un consensus à l’égard des recommandations. RÉSULTATS : Les recommandations probantes portant sur la surveillance de l’innocuité des ADG figurent dans les présentes lignes directrices. Les auteurs indiquent la qualité des recommandations relatives à des examens physiques et tests de laboratoire précis à l’égard de chaque ADG à des moments déterminés. CONCLUSION : De multiples essais aléatoires et contrôlés ont permis d’évaluer l’efficacité de bon nombre des ADG utilisés pour traiter les troubles de santé mentale en pédiatrie. Toutefois, leurs avantages ne sont pas sans risques : on observe à la fois des effets secondaires métaboliques et neurologiques chez les enfants traités au moyen d’ADG. Le risque de prise de poids, d’augmentation de l’indice de masse corporelle et de taux lipidiques anormaux est plus élevé à l’utilisation d’olanzapine, suivie de la clozapine et de la quétiapine. Quant au risque d’effets secondaires neurologiques des traitements, il est plus élevé à l’utilisation de rispéridone, d’olanzapine et d’aripiprazole. Des interventions de surveillance pertinentes des effets secondaires amélioreront la qualité des soins des enfants traités à l’aide de ces médicaments. PMID:24082813

  10. Animations proposes par le Jardin Botanique en fonction des programmes scolaires

    E-print Network

    Jeanjean, Louis

    Animations proposées par le Jardin Botanique en fonction des programmes scolaires des 3 cycles de d'une espèce et ses propres besoins. Exemple d'animation : Activité « le petit explorateur, colorier des silhouettes, des modèles. Pour les GS, écriture des nouveaux mots de la thématique. Devenir

  11. FONCTIONS DE PARTITION DU MODLE D'ISING ET DES ARBRES COUVRANTS CRITIQUES

    E-print Network

    Marckert, Jean-François

    cercle de rayon 1 et que les centres des cercles soient à l'intérieur des faces (Duffin plan de sorte que toutes ses faces soient inscrites dans un cercle de rayon 1 et que les centres des inscrites dans un cercle de rayon 1 et que les centres des cercles soient à l'intérieur des faces (Duffin

  12. [P-Demo1.4] Traitement Automatique des Langues Naturelles, Marseille, 2014

    E-print Network

    for criteria for text filtering. Mots-clés : arabe, automates, analyseurs, opérateurs linguistiques, mots'automates exprimant des règles morphosyntaxiques et des opérateurs de détection des relations discursives - 2 - des objectif de montrer : - a - la richesse des ressources linguistiques - b - le souplesse de leur utilisation

  13. Liquid metals. Concepts and theory.

    NASA Astrophysics Data System (ADS)

    March, N. H.

    A research level comprehensive introduction to the theory and concepts of liquid metals. The book begins with a survey of the basic experimental facts and reviews the concepts needed to understand the properties of liquid metals. The quantitative theory of liquid pair correlation functions, effective ion-ion interactions, thermodynamic properties, and electronic and atomic transport is then developed. The book goes on to discuss inelastic neutron scattering from bulk liquid metals, a discussion of critical behavior, magnetism, and present understanding of the liquid metal surface, binary liquid metal alloys, the two component theory of pure liquid metals, shock wave studies, liquid hydrogen plasmas, and the constitution of giant planets.

  14. Identification and quantification of neuropeptides in naïve mouse spinal cord using mass spectrometry reveals [des-Ser1]-cerebellin as a novel modulator of nociception.

    PubMed

    Su, Jie; Sandor, Katalin; Sköld, Karl; Hökfelt, Tomas; Svensson, Camilla I; Kultima, Kim

    2014-07-01

    Neuropeptide transmitters involved in nociceptive processes are more likely to be expressed in the dorsal than the ventral horn of the spinal cord. This study was designed to examine the relative distribution of neuropeptides between the dorsal and ventral spinal cord in naïve mice using liquid chromatography, high-resolution mass spectrometry. We identified and relatively quantified 36 well-characterized full-length neuropeptides and an additional 168 not previously characterized peptides. By extraction with organic solvents we identified seven additional full-length neuropeptides. The peptide [des-Ser1]-cerebellin (desCER), originating from cerebellin precursor protein 1 (CBLN1), was predominantly expressed in the dorsal horn. Immunohistochemistry showed the presence of CBLN1 immunoreactivity with a punctate cytoplasmic pattern in neuronal cell bodies throughout the spinal gray matter. The signal was stronger in the dorsal compared to the ventral horn, with most CBLN1 positive cells present in outer laminae II/III, colocalizing with calbindin, a marker for excitatory interneurons. Intrathecal injection of desCER induced a dose-dependent mechanical hypersensitivity but not heat or cold hypersensitivity. This study provides evidence for involvement of desCER in nociception and provides a platform for continued exploration of involvement of novel neuropeptides in the regulation of nociceptive transmission. Neuropeptides involved in nociceptive processes are more likely to be expressed in the dorsal than the ventral horn of spinal cord. Well-characterized full-length neuropeptides as well as uncharacterized neuropeptides were quantified by mass spectrometry. The CBLN1-derived peptide [des-Ser1]-cerebellin (desCER) is predominantly expressed in the dorsal horn, and intrathecal injection of desCER induced a dose-dependent mechanical hypersensitivity. PMID:24749662

  15. Liquid sampling system

    DOEpatents

    Larson, Loren L. (Idaho Falls, ID)

    1987-01-01

    A conduit extends from a reservoir through a sampling station and back to the reservoir in a closed loop. A jet ejector in the conduit establishes suction for withdrawing liquid from the reservoir. The conduit has a self-healing septum therein upstream of the jet ejector for receiving one end of a double-ended cannula, the other end of which is received in a serum bottle for sample collection. Gas is introduced into the conduit at a gas bleed between the sample collection bottle and the reservoir. The jet ejector evacuates gas from the conduit and the bottle and aspirates a column of liquid from the reservoir at a high rate. When the withdrawn liquid reaches the jet ejector the rate of flow therethrough reduces substantially and the gas bleed increases the pressure in the conduit for driving liquid into the sample bottle, the gas bleed forming a column of gas behind the withdrawn liquid column and interrupting the withdrawal of liquid from the reservoir. In the case of hazardous and toxic liquids, the sample bottle and the jet ejector may be isolated from the reservoir and may be further isolated from a control station containing remote manipulation means for the sample bottle and control valves for the jet ejector and gas bleed.

  16. Liquid sampling system

    DOEpatents

    Larson, L.L.

    1984-09-17

    A conduit extends from a reservoir through a sampling station and back to the reservoir in a closed loop. A jet ejector in the conduit establishes suction for withdrawing liquid from the reservoir. The conduit has a self-healing septum therein upstream of the jet ejector for receiving one end of a double-ended cannula, the other end of which is received in a serum bottle for sample collection. Gas is introduced into the conduit at a gas bleed between the sample collection bottle and the reservoir. The jet ejector evacuates gas from the conduit and the bottle and aspirates a column of liquid from the reservoir at a high rate. When the withdrawn liquid reaches the jet ejector the rate of flow therethrough reduces substantially and the gas bleed increases the pressure in the conduit for driving liquid into the sample bottle, the gas bleed forming a column of gas behind the withdrawn liquid column and interrupting the withdrawal of liquid from the reservoir. In the case of hazardous and toxic liquids, the sample bottle and the jet ejector may be isolated from the reservoir and may be further isolated from a control station containing remote manipulation means for the sample bottle and control valves for the jet ejector and gas bleed. 5 figs.

  17. Liquid metal drop ejection

    NASA Technical Reports Server (NTRS)

    Khuri-Yakub, B. T.

    1993-01-01

    The aim of this project was to demonstrate the possibility of ejecting liquid metals using drop on demand printing technology. The plan was to make transducers for operation in the 100 MHz frequency range and to use these transducers to demonstrate the ability to eject drops of liquid metals such as gallium. Two transducers were made by indium bonding piezoelectric lithium niobate to quartz buffer rods. The lithium niobate plates were thinned by mechanical polishing to a thickness of 37 microns for operation at 100 MHz. Hemispherical lenses were polished in the opposite ends of the buffer rods. The lenses, which focus the sound waves in the liquid metal, had an F-number equals 1. A mechanical housing was made to hold the transducers and to allow precise control over the liquid level above the lens. We started by demonstrating the ability to eject drops of water on demand. The drops of water had a diameter of 15 microns which corresponds to the wavelength of the sound wave in the water. A videotape of this ejection was made. We then used a mixture of Gallium and Indium (used to lower the melting temperature of the Gallium) to demonstrate the ejection of liquid metal drops. This proved to be difficult because of the oxide skin which forms on the surface of the liquid. In some instances, we were able to eject metal drops, however, this was not consistent and reproducible. An experiment was set up at NASA-Lewis to stabilize the process of drop on demand liquid metal ejection. The object was to place the transducer and liquid metal in a vacuum station so that no oxide would form on the surface. We were successful in demonstrating that liquid metals could be ejected on demand and that this technology could be used for making sheet metal in space.

  18. Liquid metal electric pump

    DOEpatents

    Abbin, J.P.; Andraka, C.E.; Lukens, L.L.; Moreno, J.B.

    1992-01-14

    An electrical pump for pumping liquid metals to high pressures in high temperature environments without the use of magnets or moving mechanical parts. The pump employs a non-porous solid electrolyte membrane, typically ceramic, specific to the liquid metal to be pumped. A DC voltage is applied across the thickness of the membrane causing ions to form and enter the membrane on the electrically positive surface, with the ions being neutralized on the opposite surface. This action provides pumping of the liquid metal from one side of the non-porous solid electrolyte membrane to the other. 3 figs.

  19. Liquid metal electric pump

    DOEpatents

    Abbin, Joseph P. (Albuquerque, NM); Andraka, Charles E. (Albuquerque, NM); Lukens, Laurance L. (Albuquerque, NM); Moreno, James B. (Albuquerque, NM)

    1992-01-01

    An electrical pump for pumping liquid metals to high pressures in high temperature environments without the use of magnets or moving mechanical parts. The pump employs a non-porous solid electrolyte membrane, typically ceramic, specific to the liquid metal to be pumped. A DC voltage is applied across the thickness of the membrane causing ions to form and enter the membrane on the electrically positive surface, with the ions being neutralized on the opposite surface. This action provides pumping of the liquid metal from one side of the non-porous solid electrolyte membrane to the other.

  20. Electrically Deformable Liquid Marbles

    E-print Network

    Edward Bormashenko; Roman Pogreb; Tamir Stein; Gene Whyman; Marcelo Schiffer; Doron Aurbach

    2011-02-17

    Liquid marbles, which are droplets coated with a hydrophobic powder, were exposed to a uniform electric field. It was established that a threshold value of the electric field, 15 cgse, should be surmounted for deformation of liquid marbles. The shape of the marbles was described as a prolate spheroid. The semi-quantitative theory describing deformation of liquid marbles in a uniform electric field is presented. The scaling law relating the radius of the contact area of the marble to the applied electric field shows a satisfactory agreement with the experimental data.

  1. Les effets des interfaces sur les proprietes magnetiques et de transport des multicouches nickel/iron et cobalt/silver

    NASA Astrophysics Data System (ADS)

    Veres, Teodor

    Cette these est consacree a l'etude de l'evolution structurale des proprietes magnetiques et de transport des multicouches Ni/Fe et nanostructures a base de Co et de l'Ag. Dans une premiere partie, essentiellement bibliographique, nous introduisons quelques concepts de base relies aux proprietes magnetiques et de transport des multicouches metalliques. Ensuite, nous presentons une breve description des methodes d'analyse des resultats. La deuxieme partie est consacree a l'etude des proprietes magnetiques et de transport des multicouches ferromagnetiques/ferromagnetiques Ni/Fe. Nous montrerons qu'une interpretation coherente de ces proprietes necessite la prise en consideration des effets des interfaces. Nous nous attacherons a mettre en evidence, a evaluer et a etudier les effets de ces interfaces ainsi que leur evolution, et ce, suite a des traitements thermiques tel que le depot a temperature elevee et l'irradiation ionique. Les analyses correlees de la structure et de la magnetoresistance nous permettront d'emettre des conclusions sur l'influence des couches tampons entre l'interface et le substrat ainsi qu'entre les couches elles-memes sur le comportement magnetique des couches F/F. La troisieme partie est consacree aux systemes a Magneto-Resistance Geante (MRG) a base de Co et Ag. Nous allons etudier l'evolution de la microstructure suite a l'irradiation avec des ions Si+ ayant une energie de 1 MeV, ainsi que les effets de ces changements sur le comportement magnetique. Cette partie debutera par l'analyse des proprietes d'une multicouche hybride, intermediaire entre les multicouches et les materiaux granulaires. Nous analyserons a l'aide des mesures de diffraction, de relaxation superparamagnetique et de magnetoresistance, les evolutions structurales produites par l'irradiation ionique. Nous etablirons des modeles qui nous aideront a interpreter les resultats pour une serie des multicouches qui couvrent un large eventail de differents comportements magnetiques et ceci en fonction de l'epaisseur de la couche magnetique de Co. Nous verrons que dans ces systemes les effets de l'irradiation ionique sont fortement influences par l'energie de surface ainsi que par l'enthalpie de formation, largement positive pour le systeme Co/Ag.

  2. 114. WEST SIDE OF LIQUID OXYGEN CONTROL ROOM (205). LIQUID ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    114. WEST SIDE OF LIQUID OXYGEN CONTROL ROOM (205). LIQUID NITROGEN (LN2) SUBCOOLER ON LEFT; SKID 8, LIQUID OXYGEN CONTROLLER FOR SWITCHING BETWEEN RAPID-LOAD AND TOPPING ON RIGHT. LIQUID OXYGEN LINE FROM SKID 9A AT RIGHT EDGE OF PHOTO. - Vandenberg Air Force Base, Space Launch Complex 3, Launch Pad 3 East, Napa & Alden Roads, Lompoc, Santa Barbara County, CA

  3. Theoretical Aspects of Liquid Crystals and Liquid Crystalline Polymers

    E-print Network

    Feng, James J.

    ­solid duality gives rise to much of the ``anomalous'' behavior of liquid crystal- line materials. WhenTheoretical Aspects of Liquid Crystals and Liquid Crystalline Polymers James J. Feng Department,'' while the lack of strong positional order allows the material to flow like ordinary fluids. This liquid

  4. Etude du processus de changement vecu par des familles ayant decide d'adopter volontairement des comportements d'attenuation des changements climatiques

    NASA Astrophysics Data System (ADS)

    Leger, Michel T.

    Les activites humaines energivores telles l'utilisation intensive de l'automobile, la surconsommation de biens et l'usage excessif d'electricite contribuent aux changements climatiques et autres problemes environnementaux. Bien que plusieurs recherches rapportent que l'etre humain est de plus en plus conscient de ses impacts sur le climat de la planete, ces memes recherches indiquent qu'en general, les gens continuent a se comporter de facon non ecologique. Que ce soit a l'ecole ou dans la communaute, plusieurs chercheurs en education relative a l'environnement estiment qu'une personne bien intentionnee est capable d'adopter des comportements plus respectueux de l'environnement. Le but de cette these etait de comprendre le processus d'integration de comportements d'attenuation des changements climatiques dans des familles. A cette fin, nous nous sommes fixe deux objectifs : 1) decrire les competences et les procedes qui favorisent l'adoption de comportements d'attenuation des changements climatiques dans des familles et 2) decrire les facteurs et les dynamiques familiales qui facilitent et limitent l'adoption de comportements d'attenuation des changements climatiques dans des familles. Des familles ont ete invitees a essayer des comportements personnels et collectifs d'attenuation des changements climatiques de sorte a integrer des modes de vie plus ecologiques. Sur une periode de huit mois, nous avons suivi leur experience de changement afin de mieux comprendre comment se produit le processus de changement dans des familles qui decident volontairement d'adopter des comportements d'attenuation des changements climatiques. Apres leur avoir fourni quelques connaissances de base sur les changements climatiques, nous avons observe le vecu de changement des familles durant huit mois d'essais a l'aide de journaux reflexifs, d'entretiens d'explicitation et du journal du chercheur. La these comporte trois articles scientifiques. Dans le premier article, nous presentons une recension des ecrits sur le changement de comportement en environnement. Nous explorons egalement la famille comme systeme fonctionnel de sorte a mieux comprendre ce contexte d'action environnementale qui est, a notre connaissance, peu etudie. Dans le deuxieme article, nous presentons nos resultats de recherche concernant les facteurs d'influence observes ainsi que les competences manifestees au cours du processus d'adoption de nouveaux comportements environnementaux dans trois familles. Enfin, le troisieme article presente les resultats du cas d'une quatrieme famille ou les membres vivent depuis longtemps des modes de vie ecologique. Dans le cadre d'une demarche d'analyse par theorisation ancree, l'etude de ce cas modele nous a permis d'approfondir les categories conceptuelles identifiees dans le deuxieme article de sorte a produire une modelisation de l'integration de comportements environnementaux dans le contexte de la famille. Les conclusions degagees grace a la recension des ecrits nous ont permis d'identifier les elements qui pourraient influencer l'adoption de comportements environnementaux dans des familles. La recension a aussi permis une meilleure comprehension des divers facteurs qui peuvent affecter l'adoption de comportements environnementaux et, enfin, elle a permis de mieux cerner le phenomene de changement de comportement dans le contexte de la famille consideree comme un systeme. En appliquant un processus d'analyse inductif, a partir de nos donnees qualitatives, les resultats de notre etude multi-cas nous ont indique que deux construits conceptuels semblent influencer l'adoption de comportements environnementaux en famille : 1) les valeurs biospheriques communes au sein de la famille et 2) les competences collectivement mises a profit collectivement durant l'essai de nouveaux comportements environnementaux. Notre modelisation du processus de changement dans des familles indique aussi qu'une dynamique familiale collaborative et la presence d'un groupe de soutien exterieur sont deux elements conceptuels qui tendent a influencer les deux princi

  5. Extensible automated dispersive liquid-liquid microextraction.

    PubMed

    Li, Songqing; Hu, Lu; Chen, Ketao; Gao, Haixiang

    2015-05-01

    In this study, a convenient and extensible automated ionic liquid-based in situ dispersive liquid-liquid microextraction (automated IL-based in situ DLLME) was developed. 1-Octyl-3-methylimidazolium bis[(trifluoromethane)sulfonyl]imide ([C8MIM]NTf2) is formed through the reaction between [C8MIM]Cl and lithium bis[(trifluoromethane)sulfonyl]imide (LiNTf2) to extract the analytes. Using a fully automatic SPE workstation, special SPE columns packed with nonwoven polypropylene (NWPP) fiber, and a modified operation program, the procedures of the IL-based in situ DLLME, including the collection of a water sample, injection of an ion exchange solvent, phase separation of the emulsified solution, elution of the retained extraction phase, and collection of the eluent into vials, can be performed automatically. The developed approach, coupled with high-performance liquid chromatography-diode array detection (HPLC-DAD), was successfully applied to the detection and concentration determination of benzoylurea (BU) insecticides in water samples. Parameters affecting the extraction performance were investigated and optimized. Under the optimized conditions, the proposed method achieved extraction recoveries of 80% to 89% for water samples. The limits of detection (LODs) of the method were in the range of 0.16-0.45 ng mL(-1). The intra-column and inter-column relative standard deviations (RSDs) were <8.6%. Good linearity (r>0.9986) was obtained over the calibration range from 2 to 500 ng mL(-1). The proposed method opens a new avenue for automated DLLME that not only greatly expands the range of viable extractants, especially functional ILs but also enhances its application for various detection methods. Furthermore, multiple samples can be processed simultaneously, which accelerates the sample preparation and allows the examination of a large number of samples. PMID:25892068

  6. Diet - clear liquid

    MedlinePLUS

    ... juices without pulp, such as grape juice, filtered apple juice, and cranberry juice Soup broth (bouillon or ... might ask you to avoid liquids that have red coloring for some tests, like a colonoscopy.

  7. Liquid metal boiling inception

    NASA Technical Reports Server (NTRS)

    Sabin, C. M.; Poppendiek, H. F.; Mouritzen, G.; Meckel, P. T.; Cloakey, J. E.

    1972-01-01

    An experimental study of the inception of boiling in potassium in forced convection is reported. The boiler consisted of a 0.19-inch inside diameter, niobium-1% zirconium boiler tube approximately six feet long. Heating was accomplished by direct electrical tube wall conduction. Experiments were performed with both all-liquid fill and two-phase fill startup sequences and with a range of flow rates, saturation temperatures, inert gas levels, and fill liquid temperatures. Superheat of the liquid above the equilibrium saturation temperature was observed in all the experiments. Incipient boiling liquid superheat ranged from a few degrees to several hundred. Comparisons of these data with other data and with several analytical treatments are presented.

  8. Safer Liquid Natural Gas

    NASA Technical Reports Server (NTRS)

    1976-01-01

    After the disaster of Staten Island in 1973 where 40 people were killed repairing a liquid natural gas storage tank, the New York Fire Commissioner requested NASA's help in drawing up a comprehensive plan to cover the design, construction, and operation of liquid natural gas facilities. Two programs are underway. The first transfers comprehensive risk management techniques and procedures which take the form of an instruction document that includes determining liquid-gas risks through engineering analysis and tests, controlling these risks by setting up redundant fail safe techniques, and establishing criteria calling for decisions that eliminate or accept certain risks. The second program prepares a liquid gas safety manual (the first of its kind).

  9. Liquid crystal bilayer wall

    E-print Network

    Aksay, Ilhan A.

    to a liquid crystal solution of hexanol, cetylpyridinium chloride, and 0.2 M hydrochloric acid, and our hexanol, cetylpyridinium chloride, and 1 wt % aqueous NaCl solution.[1] This phase, which is optically

  10. Liquidity facilities and signaling

    E-print Network

    Arregui, Nicolás

    2010-01-01

    This dissertation studies the role of signaling concerns in discouraging access to liquidity facilities like the IMF contingent credit lines (CCL) and the Discount Window (DW). In Chapter 1, I analyze the introduction of ...

  11. Liquid medication administration

    MedlinePLUS

    ... cooking are accurate, but they spill easily. Oral syringes have some advantages for giving liquid medications. They ... easy to use. You can take a capped syringe containing a dose of medication to your child's ...

  12. The Liquid Nitrogen Fountain

    NASA Astrophysics Data System (ADS)

    McRae, Robin; Rahn, Jeffrey A.; Beamer, Timothy W.; Lebret, Norm

    2002-10-01

    Details of a demonstration using liquid nitrogen are presented. The demonstration is based on a 500-mL transparent polyethylene soft-drink bottle with a screw-on pop-up drink top. Prior to the demonstration, a balloon is placed over the popped-up spout of the bottle top. The bottle is filled with liquid nitrogen and the top, with the balloon affixed, is quickly put in place and screwed on tightly. As the liquid nitrogen in the bottle boils, the balloon inflates. When the balloon bursts the noise produced is far greater than would ordinarily be expected, and a fountain of liquid nitrogen and condensing water vapor shoots into the air above the bottle.

  13. Capacitance cell for liquids

    NASA Astrophysics Data System (ADS)

    Jacobs, D. T.; Greer, S. C.

    1980-07-01

    We present a simple and chemically inert, guarded cylindrical capacitance cell for liquids in the temperature range 170 to 370 K and at pressures near atmospheric. A precision in the dielectric constant of 2 ppm is realizable with this cell.

  14. Liquid cooled garments

    NASA Technical Reports Server (NTRS)

    1975-01-01

    Liquid cooled garments employed in several applications in which severe heat is encountered are discussed. In particular, the use of the garments to replace air line cooling units in a variety of industrial processing situations is discussed.

  15. Diet - full liquid

    MedlinePLUS

    ... liquid when they are at room temperature, like ice cream. It also includes: Strained creamy soups Tea Juice ... Butter, margarine, oil, cream, custard, and pudding Plain ice cream, frozen yogurt, and sherbet. Fruit ices and popsicles ...

  16. Liquid blocking check valve

    DOEpatents

    Merrill, John T. (Pleasant Hill, CA)

    1984-01-01

    A liquid blocking check valve useful particularly in a pneumatic system utilizing a pressurized liquid fill chamber. The valve includes a floatable ball disposed within a housing defining a chamber. The housing is provided with an inlet aperture disposed in the top of said chamber, and an outlet aperture disposed in the bottom of said chamber in an offset relation to said inlet aperture and in communication with a cutaway side wall section of said housing.

  17. Applications of ionic liquids.

    PubMed

    Patel, Divia Dinesh; Lee, Jong-Min

    2012-06-01

    Ionic liquids have recently gained popularity in the scientific community owing to their special properties and characteristics. One of the reasons why ionic liquids have been termed "green solvents" is due to their negligible vapour pressure. Their use in electrochemical, biological and metal extraction applications is discussed. Wide research has been carried out for their use in batteries, solar panels, fuel cells, drug deliveries and biomass pretreatments. This work aims to consolidate the various findings from previous works in these areas. PMID:22711528

  18. Liquid cooled helmet

    NASA Technical Reports Server (NTRS)

    Elkins, William (Inventor); Williams, Bill A. (Inventor)

    1979-01-01

    Liquid cooled helmet comprising a cap of flexible material adapted to fit the head of a person, cooling panels mounted inside the cap forming passageways for carrying a liquid coolant, the panels being positioned to engage the cranium and neck of a person wearing the helmet, inlet and outlet lines communicating with the passageways, and releasable straps for securing the helmet about the neck of the wearer.

  19. Liquid Level Sensing System

    NASA Technical Reports Server (NTRS)

    Korman, Valentin (Inventor); Wiley, John T. (Inventor); Duffell, Amanda G. (Inventor)

    2014-01-01

    A liquid level sensing system includes waveguides disposed in a liquid and distributed along a path with a gap between adjacent waveguides. A source introduces electromagnetic energy into the waveguides at a first end of the path. A portion of the electromagnetic energy exits the waveguides at a second end of the path. A detector measures the portion of the electromagnetic energy exiting the second end of the path.

  20. Wahlfach II: Sonographie des Abdomens Modul-Code: MSE_WP 568

    E-print Network

    Manstein, Dietmar J.

    Wahlfach II: Sonographie des Abdomens Modul-Code: MSE_WP 568 Wahlpflichtveranstaltung mit 5, empfohlen im Freitertial Lernziele Praktische Sonographie des Abdomens: Grundkenntnisse Gerätetechnik. Bildoptimierung. Sonographische Anatomie in ausgewählten Standardebenen des Abdomens. Selbständige Durchführung

  1. Les tannins : Les tannins (ou tanins, du franais tan, corce, mot issu du gaulois) sont des

    E-print Network

    . Enfin, des tannins particuliers, ou phlorotannins, existent chez les algues hétérocontes (Phéophytes ou'astringence en bouche des végétaux verts et des vins trop jeunes (réaction tannins vacuolaires / protéines

  2. Liquid crystalline composites containing phyllosilicates

    DOEpatents

    Chaiko, David J.

    2004-07-13

    The present invention provides phyllosilicate-polymer compositions which are useful as liquid crystalline composites. Phyllosilicate-polymer liquid crystalline compositions of the present invention can contain a high percentage of phyllosilicate while at the same time be transparent. Because of the ordering of the particles liquid crystalline composite, liquid crystalline composites are particularly useful as barriers to gas transport.

  3. Formation en Aliments Sant et Technologie (FAST) Le programme FAST a comme mission de former des professionnels et des jeunes chercheurs

    E-print Network

    Formation en Aliments Santé et Technologie (FAST) Le programme FAST a comme mission de former des professionnels et des jeunes chercheurs ayant acquis non seulement une expertise de pointe en recherche, mais produits, de mise en marché et de réglementation. Le secteur des aliments santé et des technologies est

  4. Comportement rhéologique des systèmes mixtes biopolymères / protéines

    NASA Astrophysics Data System (ADS)

    Rebiha, M.; Moulai-Mostefa, N.; Sadok, A. Hadj; Sabri, N.

    2005-05-01

    Dans ce travail, on s'est intéressé à l'étude des effets du caséinate de sodium et du xanthane sur les propriétés rhéologiques des solutions aqueuses, préparées suivant un plan d'expériences. Les caractéristiques mécaniques obtenues sont traduites par les coefficients du modèle rhéologique de Casson, en l'occurrence la contrainte seuil, ? 0, et la viscosité plastique, ? _c. Ainsi, à l'issue de la modélisation en surface de réponses, il apparaît une interaction répulsive à l'échelle structurale entre le caséinate de sodium et le xanthane, traduite par un abaissement considérable de ? 0. Cet baissement de la rigidité peut conduire à une séparation de phases, phénomène conditionné par la viscosité limite de Casson,? _c.

  5. Plan stratgique 2015-2020 Facult des sciences

    E-print Network

    Laval, Université

    Plan stratégique 2015-2020 Faculté des sciences de l'agriculture et de l'alimentation #12;www.fsaa.ulaval.ca Notre mission La Faculté des sciences de l'agriculture et de l'alimentation est un acteur majeur dans le Faculté des sciences de l'agriculture et de l'alimentation par la richesse et l'expertise de ses membres

  6. BACCALAURAT COOPRATIF EN GNIE DES MINES ET DE LA MINRALURGIE

    E-print Network

    Laval, Université

    département GML-2002 Thermodynamique 3 H 4 PR : GML-1001 et MAT-1900 GGL-2601 Analyse et modélisation des, le cas échéant, aux exigences indiquées ci-après. I. COURS DE CONCENTRATION (15 crédits) Choisir l'une des deux concentrations (A ou B): A) EXPLOITATION MINI�RE (15 crédits) GCI-1002 Mécanique des sols I 3

  7. LE DEVENIR DES DOCTEURS DE L'UFC PROMOTION 2008

    E-print Network

    Jeanjean, Louis

    microtechniques (SPIM), Louis Pasteur, et Langages, espaces, temps, sociétés (LETS). Les profils différent selon première inscription en thèse. Louis Pasteur : deux tiers sont des hommes, la durée moyenne des thèses est, SPIM et Louis Pasteur, plus de 95 % des docteurs sont en emploi 3 ans après la soutenance de thèse

  8. Devenir des diplms de Master Recherche

    E-print Network

    Sart, Remi

    , une vue globalisée du devenir des diplômés de Master Recherche de l'Université Blaise Pascal, toutes spécialités confondues. Fiche 1 : Vue d'ensemble sur les Masters Recherche de l'Université Blaise Pascal Blaise Pascal #12;Région parisienne 3,8%(6) Limousin 2,5%(4) Rhône-Alpes 5,1%(8) Auvergne 67

  9. INAUGURATION DE LA CRECHE DES CEZEAUX

    E-print Network

    Sart, Remi

    INAUGURATION DE LA CRECHE DES CEZEAUX Clermont-Ferrand, le 13 octobre 2015 UNIVERSIT� BLAISE PASCAL porté par le PRES Clermont université, il est porté depuis janvier 2015 par l'Université Blaise Pascal. Tous les personnels et étudiants de l'Université Blaise Pascal sont éligibles à une place en crèche

  10. Devenir des diplms de Master Recherche

    E-print Network

    Sart, Remi

    leur diplôme. Concernant les Masters Recherche de l'Université Blaise Pascal, les 240 diplômés de la, une vue globalisée du devenir des diplômés de Master Recherche de l'Université Blaise Pascal, toutes spécialités confondues. Fiche 1 : Vue d'ensemble sur les Masters Recherche de l'Université Blaise Pascal

  11. Introduction l'architecture des ordinateurs

    E-print Network

    Silber, Georges-André

    be built on a single wafer." http://en.wikipedia.org/wiki/Moore's_law 1965 #12;Deuxième Loi de Moore 1975 Le nombre de transistors des microprocesseurs sur une puce de silicium double tous les deux ans. http://en.wikipedia.org/wiki/Moore's_law jusqu'à ce qu'il soit limité par la loi de Moore. Il n'atteindra jamais un stade de maturité

  12. Profil anthropometrique des enfants scolarises tananariviens

    PubMed Central

    Razafimanantsoa, Fetralinjiva; Razafindramaro, Notahiana; Raherimandimby, Hasina; Robinson, Annick; RakotoAlson, Olivat; Rasamindrakotroka, Andry

    2013-01-01

    Les enfants tananariviens sont en état de malnutrition chronique. Notre objectif est d’évaluer l'indice de masse corporelle (IMC) pour estimer les enfants apparemment "sains". Une enquête et une mesure de la taille et du poids des enfants scolarisés tananariviens de 6 à 11 ans ont été réalisées. Après leur accord, la taille et l'indice de masse corporelle des 442 enfants tirés au hasard ont été ainsi obtenus. L'analyse de la moyenne de la taille a révélé une différence significative à 8 ans, une différence non évidente sur l'indice de masse corporelle. La comparaison avec les valeurs de référence (OMS 2006) a montré un retard statural de 34% avec une tendance globale à la hausse et un déficit pondéral égal à 5,5% selon le z score. Ainsi, au sein d'une population malnutrie, l'indice de masse corporelle pourrait être utilisé comme un des paramètres à considérer dans l’évaluation de l’état de santé pour classer ces enfants en bonne santé apparente. PMID:24711862

  13. Newtons Universum. Materialien zur Geschichte des Kraftbegriffes.

    NASA Astrophysics Data System (ADS)

    Mit einem Vorwort von E. Seibold und einer Einführung von W. Neuser. This book is a selection of 15 articles published in the journal "Spektrum der Wissenschaft". The original English versions of the papers were first published in "Scientific American". Contents: 1. Impetustheorie und Intuition in der Physik (M. McCloskey). 2. Mittelalterliche Ursprünge der industriellen Revolution (T. S. Reynolds). 3. Leonardo da Vincis Beiträge zur theoretischen Mechanik (V. Foley, W. Soedel). 4. Nikolaus Kopernikus und Tycho Brahe (O. Gingerich). 5. Keplers Entdeckung der ersten beiden Planetengesetze (C. Wilson). 6. Galileis Entdeckung des Fallgesetzes (S. Drake). 7. Galileis Beobachtung des Neptun (S. Drake, C. T. Kowal). 8. Galileo Galilei und der Schatten des Giordano Bruno (L. S. Lerner, E. A. Gosselin). 9. Der Fall Galilei (O. Gingerich). 10. Newtons Apfel und Galileis "Dialog" (S. Drake). 11. Newtons Gravitationsgesetz - aus Formeln wird eine Idee (I. B. Cohen). 12. Christopher Wren: Astronom und Architekt (H. Dorn, R. Mark). 13. Atomismus und Kräfte in der Geschichte (L. Holliday). 14. Ein Elitezirkel vor 200 Jahren: Die Lunar Society von Birmingham (L. Ritchie-Calder). 15. Sadi Carnot: Technik und Theorie der Dampfmaschine (S. S. Wilson).

  14. Inhomogeneites dans le Vent des Etoiles Wolf-Rayet

    NASA Astrophysics Data System (ADS)

    Robert, Carmelle

    1992-01-01

    Des mesures spectroscopiques effectuees avec un haut rapport signal sur bruit et une bonne resolution ont demontre l'existence de regions perturbees en mouvement dans le vent d'etoiles Wolf-Rayet (WR). L'echantillon d'objets etudies ici comprend 9 etoiles WR couvrant differents sous-types WN et WC. De nombreuses petites structures variables superposees au profil des raies d'emission formees dans le vent stellaire signalent la presence des perturbations. L'etude des variations globales des raies et l'examen des micro-structures individuelles ont permis de decrire plusieurs caracteristiques des perturbations. Entre autres, on observe des correlations significatives entre le niveau de variabilite des raies et certains parametres des etoiles qui confirment que le phenomene de variabilite est intrinseque au vent stellaire. En comparant les changements des vitesses radiales et des largeurs equivalentes des differentes raies d'une meme etoile, on conclut que les regions perturbees ont une etendue finie par rapport a l'enveloppe des etoiles. On peut facilement suivre les structures individuelles sur une periode de temps couvrant ~eq8 heures (et peut etre meme 24 heures) avant qu'elles ne disparaissent. Durant ce temps les structures se deplacent en s'eloignant du centre de la raie. A partir des differents comportements notes lors de l'analyse des variations globales et lors de l'examen des structures individuelles, on propose de representer les perturbations par un modele d'inhomogeneites discretes en expansion dans le vent. On suppose simplement que les inhomogeneites emettent comme le vent global (et absorbent aussi si le vent global montre un profil P Cyg). La superposition du graphique de l'acceleration radiale moyenne des inhomogeneites de WR140 en fonction de leur vitesse radiale et du modele theorique d'inhomogeneites qui suivent la loi generale de vitesse donne un taux d'acceleration lent, avec beta >= 3 pour les inhomogeneites de cette etoile. On obtient, entre autres, une correlation entre le nombre d'inhomogeneites detectees et la vitesse terminale. Cette relation explique bien l'anti-correlation observee entre le niveau de variabilite spectroscopique, photometrique ou polarimetrique et la vitesse terminale. On estime pour toutes les etoiles une masse moyenne des inhomogeneites de 7 times 10^{ -10} Modot et un taux de perte de masse sous la forme d'inhomogeneites detectables qui correspond a 10% de la perte de masse du vent total. L'histogramme du nombre d'inhomogeneites en fonction du leur flux pourrait cependant predire l'existence d'un grand nombre de petites structures non-detectees ici a cause du rapport signal sur bruit relativement trop faible. Ce resultat interessant, qui demande cependant a etre verifie, suggere que le vent pourrait etre forme d'un ensemble quasi infini d'inhomogeneites. En ajustant une loi de puissance dans l'histogramme du flux de chaque etoile, on calcule, pour les plus grosses structures, un exposant = -2.4 +/- 0.2. On constate alors que cette valeur est compatible avec celle que predit la turbulence supersonique. Les structures observees dans les spectres des etoiles WR ont des caracteristiques tres semblables a celles des etoiles O. On propose alors que les perturbations observees chez ces 2 types d'etoiles ont une meme origine. Parmi les mecanismes deja proposes dans le passe pour expliquer les variations des etoiles O et WR (instabilites radiatives, pulsations et champ magnetique) on ne saurait encore dire <=uel, ou lesquels, correspondent le mieux aux observations. Dans les projets futurs, on propose de considerer aussi le role que pourrait avoir la turbulence pour expliquer les perturbations du vent stellaire.

  15. A novel dicationic phenoxaphosphino-modified xantphos-type ligand--a unique ligand specifically designed for a high activity, selectivity and recyclability.

    PubMed

    Bronger, Raymond P J; Silva, Silvana M; Kamer, Paul C J; van Leeuwen, Piet W N M

    2002-12-21

    A novel phenoxaphosphino-modified ligand has been prepared and successfully employed in the rhodium catalysed hydroformylation of 1-octene in ionic liquids showing unprecedented high selectivity and activity without detectable rhodium or phosphorus leaching during recycling experiments. PMID:12536808

  16. Prise en charge des complications des fistules artério-veineuses pour hémodialyse chronique

    PubMed Central

    Jiber, Hamid; Zrihni, Youssef; Zaghloul, Rachid; Hajji, Rita; Zizi, Othman; Bouarhroum, Abdellatif

    2015-01-01

    La fistule artério-veineuse native est l'accès vasculaire de choix pour l'hémodialyse chronique en raison de sa longévité, son taux faible de complication et de mortalité par rapport aux pontages artério-veineux et aux cathéters. Cependant, il arrive assez souvent que l'on assiste à des complications qui sont dominées par la sténose et la thrombose. C'est une étude rétrospective des complications ayants survenues pour 31 fistules artério-veineuses pour hémodialyse chronique des 200 fistules réalisées chez 200 patients au sein du service de chirurgie vasculaire du CHU Hassan II de Fès sur une période de trois ans, étendue de Janvier 2007 à Décembre 2009. Ces complications ont été présentés par les thromboses dans 14 cas soit 45,15% de l'ensemble des complications, les sténoses dans 4 cas (12,90%,) les anévrismes dans 4 cas (12,90%), les complications ischémiques dans 3 cas (9,67%), l'infection dans 3 cas (9,67%), l'hémorragie dans 2 cas (6,45%) et l’ hyperdébit dans un seul cas soit 3,22%. On a pu conserver 22 fistules soit 70,96% par traitement chirurgical ou endovasculaire, on a confectionné une nouvelle fistule dans 8 cas soit 25,80%, et on a adressé une patiente (3,22%) pour pose d'un cathéter veineux tunnelisé permanent. Les complications des fistules artério-veineuses pour l'hémodialyse chronique sont la principale cause de morbidité chez les patients hémodialysés, il est donc important de s'impliquer lors de leur création, et de donner un maximum d'attention quand ils sont manipulés. Ceci suggère la mise en place d'un programme de surveillance de ces fistules en raison de l'impact des complications sur la morbi-mortalité du patient hémodialysé et sur le plan financier. PMID:26113933

  17. Utilisation des matériaux luminescents pour la métrologie des faisceaux intenses UVX d'impulsions ultracourtes

    NASA Astrophysics Data System (ADS)

    Fedorov, N.; Nagirnyi, V.; Vasil'Ev, A.; Belsky, A.; Carré, B.; Feldbach, E.; Gaudin, J.; Geoffroy, G.; Guizard, S.; de Grazia, M.; Kirm, M.; Martin, P.; Merdji, H.

    2006-12-01

    Récemment nous avons débuté des séries d'expériences sur l'interaction d'impulsions intenses VUV avec les solides luminescents. Le but principal en est l'étude des mécanismes d'interaction et de transfert d'énergie entre les excitations électroniques dans les solides à large bande interdite. L'application directe de ces études sera le développement de matériaux et de méthodes de métrologie pour les faisceaux UVX intenses. Nous présentons les résultats obtenus pour CdWO{4} qui montrent que ce cristal pourra servir comme un scintillateur pour le rayonnement VUV intense.

  18. Que peut-on voir avec des neutrons? Une introduction pour des non spécialistes

    NASA Astrophysics Data System (ADS)

    Schweizer, J.

    2005-11-01

    Le neutron est une particule élémentaire qui a été découverte en 1932 par James Chadwick. Ses caractéristiques principales sont résumées dans le tableau I. Il a été utilisé pour la première fois par Clifford Shull en 1946 comme outil pour des expériences de diffusion. Cette technique s'est depuis constamment développée pour concerner tous les aspects de la matière condensée: physique, chimie, matériaux, biologie. Il s'agit d'un outil tout à fait exceptionnel car le neutron possède des propriétés uniques et particulièrement adaptées pour ces études.

  19. Les effets du travail en equipe dans l'apprentissage par projets sur la motivation des etudiantes et des etudiants en formation des ingenieurs

    NASA Astrophysics Data System (ADS)

    Fernandez, Nicolas

    Les representants des secteurs industriels et les, milieux professionnels en Amerique du Nord reprochaient aux universites de former des ingenieurs avec peu d'experience pratique en resolution de problemes et en conception. Quelques programmes de genie ont alors mis en place le travail en equipe dans l'apprentissage par projets. Beaucoup d'ecrits font valoir les benefices de l'apprentissage par projets sur la motivation des etudiants. Or, ces benefices commencent a peine a faire l'objet de recherches visant a produire des donnees probantes a ce sujet. Les travaux sur la motivation en contexte d'apprentissage et les modeles theoriques developpes sont issus d'environnements d'apprentissage marques par l'enseignement magistral. Le modele de la valeur attendue de la tache (Eccles et Wigfield, 1995; Neuville, 2004) et le modele du systeme-groupe (St-Arnaud, 2008) ont ete retenus pour mesurer les effets du travail en equipe dans l'apprentissage par projets sur la motivation. La recherche visait aussi a approfondir et a nuancer la comprehension de la motivation des etudiants universitaires apprenant en contexte innovant. Les sujets constituent des etudiants (n=100) travaillant sur des projets d'integration au cours des trois sessions initiales du programme de genie mecanique d'une universite canadienne. L'analyse de regression multiple revele que les construits de la motivation expliquent un tiers de la variance de l'engagement academique dans la realisation du projet d'integration. Les perceptions de l' "expectancy", de la valeur intrinseque et utilitaire sont les determinants principaux de l'engagement des etudiants. L'analyse de variance multivariee a mesures repetees indique que la motivation des etudiants pour le travail sur les projets d'integration a augmente au cours des trois sessions initiales du parcours de formation. Finalement, malgre l'absence d'interaction significative entre les variables de motivation et de l'equipe, les reponses des sujets indiquent une amelioration du travail en equipe au terme des trois sessions. Mots cle: 1. apprentissage par projet; 2. projets d'integration; 3. travail en equipe; 4. motivation; 5. valeur attendue de la tache; 6. expectancy; 7. valeur intrinseque; 8. valeur utilitaire; 9. formation d'ingenieurs; 10. analyse quantitative.

  20. Implications of liquid-liquid distribution coefficients to mineral-liquid partitioning

    NASA Technical Reports Server (NTRS)

    Ryerson, F. J.; Hess, P. C.

    1978-01-01

    In order to evaluate the influence of a silicate liquid structure on mineral-liquid partitioning, element partitioning data is obtained for coexisting anhydrous immiscible granitic and ferrobasaltic magmas. It is found that: (1) mineral-liquid distribution coefficients indicate the competition of crystal and liquid for cation incorporation, (2) increased polymerization of the residual liquid during crystal-liquid fractionation increases the mineral-liquid distribution coefficients for high-charge-density cations, (3) incompatible element ratios of low- and high-charge-density cations may vary during crystal-liquid fractionation because of changes in the melt composition and structure, (4) relative solubilities of REE's in melts do not vary with melt polymerization, (5) the changes of Sm/Eu ratios during crystal-liquid fractionation depend on the melt composition, and (6) minor components and volatiles can significantly influence the silicate melt structure and the mineral-liquid distribution coefficients.

  1. Control of the Liquid-Liquid Transition in a Molecular Liquid by Spatial Confinement Rei Kurita and Hajime Tanaka*

    E-print Network

    Weeks, Eric R.

    Control of the Liquid-Liquid Transition in a Molecular Liquid by Spatial Confinement Rei Kurita to nanotechnology. Here we report the first systematic experimental study on confinement effects on a liquid-liquid transition of a molecular liquid. We found that one liquid can be transformed into another purely by spatial

  2. Révision systématique des effets de la fréquence des repas en famille sur les résultats psychosociaux chez les jeunes

    PubMed Central

    Harrison, Megan E.; Norris, Mark L.; Obeid, Nicole; Fu, Maeghan; Weinstangel, Hannah; Sampson, Margaret

    2015-01-01

    Résumé Objectif Effectuer une révision systématique des effets de repas en famille fréquents sur les résultats psychosociaux chez les enfants et les adolescents et examiner s’il existe des différences dans les résultats selon le sexe. Sources des données Des études ont été cernées à la suite d’une recherche dans MEDLINE (de 1948 à la dernière semaine de juin 2011) et dans PsycINFO (de 1806 à la première semaine de juillet 2011) à l’aide de l’interface Ovide. Les expressions et mots clés MeSH utilisés seuls ou en combinaisons étaient les suivants : family, meal, food intake, nutrition, diets, body weight, adolescent attitudes, eating behaviour, feeding behaviour et eating disorders. Les bibliographies des articles jugés pertinents ont aussi été passées en revus. Sélection des études La recherche initiale a produit 1783 articles. Pour être incluses dans l’analyse, les études devaient répondre aux critères suivants : être publiées en anglais dans une revue révisée par des pairs; porter sur des enfants ou des adolescents; traiter de l’influence des repas en famille sur les paramètres psychosociaux (p. ex. consommation de drogues et autres substances, troubles de l’alimentation, dépression) chez les enfants ou les adolescents; avoir une conception d’étude appropriée, notamment des méthodes statistiques acceptables pour l’analyse des paramètres. Quatorze articles satisfaisaient aux critères d’inclusion. Deux examinateurs indépendants ont étudié et analysé les articles. Synthèse Dans l’ensemble, les résultats font valoir que la fréquence des repas en famille est inversement proportionnelle aux troubles de l’alimentation, à la consommation d’alcool et de drogues, aux comportements violents, aux sentiments de dépression ou aux pensées suicidaires chez les adolescents. Il existe une relation positive entre de fréquents repas en famille, une bonne estime de soi et la réussite scolaire. Les études révèlent des différences considérables dans les résultats chez les enfants et adolescents masculins et féminins, les sujets féminins ayant des résultats plus positifs. Conclusion Cette révision systématique vient confirmer davantage qu’il convient de préconiser de fréquents repas en famille. Tous les professionnels de la santé devraient renseigner les familles concernant les bienfaits de prendre régulièrement ensemble des repas.

  3. Nyomárka y Istv án: Rövid hor vát és szerb nyelvtörténet [Kurze Geschichte des Kroatischen und des Serbischen

    E-print Network

    Vig, Istvá n

    2009-01-01

    Mariboru, Filozofska fakulteta, blanka.bosnjak@uni-mb.si NyoMáRKAy ISTVáN: RöviD hORváT és szeRB NyeLvTöR- TéNeT [Kurze Geschichte des Kroatischen und des Serbischen]. Budapest: ELTE Szláv Filológiai Tanszék, 2007. opera Slavica Bu- dapestinensia... Nyomárkay veröffentlichtete schon mehrere Bücher, die als Neuheit in verschiedenen Forschungsbereichen gelten. Auch sein letztes Werk gehört zu dieser Tradition. Es handelt sich um die erste auf Ungarisch verfasste Geschich- te des Kroatischen und des...

  4. Une recension des écrits concernant la réalité psychoaffective des femmes ayant une vulvodynie : Difficultés rencontrées et stratégies développées

    PubMed Central

    Cantin-Drouin, Maude; Damant, Dominique; Turcotte, Daniel

    2008-01-01

    HISTORIQUE : Au cours des trois dernières décennies, une attention grandissante a été portée à l’étude du syndrome de vulvodynie, soit un inconfort vulvaire chronique inexpliqué, éprouvé en l’absence de pathologie précisée. En plus d’avoir des répercussions physiques, l’expérience de la vulvodynie comporte une dimension psychosociale. OBJECTIF : Cet article vise à faire une recension des écrits sur la réalité psychoaffective des femmes qui éprouvent une vulvodynie. MÉTHODE : Une recherche documentaire basée sur une exploration systématique de textes présentant des résultats de recherche et recensés dans les principales banques de données en sciences sociales, dont Dissertation Abstracts, Current Contents et PsycINFO, a été réalisée. RÉSULTATS : Cette recension des écrits révèle, malgré la présence de certains résultats divergents, que les femmes ayant une vulvodynie affrontent souvent des difficultés identitaires et psychologiques, qui sont influencées notamment par les normes sociales de sexualité et de féminité. Pour composer avec ces difficultés, les femmes développent différentes stratégies visant à diminuer le stress occasionné par la douleur et à améliorer leur bien-être psychologique. CONCLUSION : Les difficultés relationnelles et psychologiques vécues par les femmes ayant une vulvodynie ne découlent pas seulement de la douleur physique, mais aussi du sens qu’elles lui accordent, souvent influencé par les discours sociaux sur l’hétérosexualité et la féminité. Il importe donc d’intervenir auprès des femmes en tenant compte de l’influence du contexte social tout en poursuivant le développement des connaissances sur les aspects psychosociaux de cette expérience. PMID:18592063

  5. Microgravity liquid propellant management

    NASA Technical Reports Server (NTRS)

    Hung, R. J.

    1990-01-01

    The requirement to settle or to position liquid fluid over the outlet end of a spacecraft propellant tank prior to main engine restart, poses a microgravity fluid behavior problem. Resettlement or reorientation of liquid propellant can be accomplished by providing optimal acceleration to the spacecraft such that the propellant is reoriented over the tank outlet without any vapor entrainment, any excessive geysering, or any other undersirable fluid motion for the space fluid management under microgravity environment. The most efficient technique is studied for propellant resettling through the minimization of propellant usage and weight penalties. Both full scale and subscale liquid propellant tank of Space Transfer Vehicle were used to simulate flow profiles for liquid hydrogen reorientation over the tank outlet. In subscale simulation, both constant and impulsive resettling acceleration were used to simulate the liquid flow reorientation. Comparisons between the constant reverse gravity acceleration and impulsive reverse gravity acceleration to be used for activation of propellant resettlement shows that impulsive reverse gravity thrust is superior to constant reverse gravity thrust.

  6. Antiferromagnetic marginal Fermi liquid

    SciTech Connect

    Zimanyi, G.T. ); Bedell, K.S. )

    1993-09-01

    The infrared singularities of the marginal-Fermi-liquid theory are treated within a perturbative renormalization-group approach for the original, weakly-momentum-dependent model. Then an alternative framework is introduced: marginal Fermi liquids with strong antiferromagnetic fluctuations. The models in both cases are found to be stable in a limited range of parameters, otherwise non-Fermi-liquid behavior is obtained. Comparison with experiments on the conductivity and spin susceptibility yields quite reasonable agreement between theory and the data in the case of the antiferromagnetic formulation. Trends with the doping and differences between copper and oxygen relaxation rates also gain a natural explanation. Analogies with the Luttinger-liquid ideas are also explored. Finally the antiferromagnetic marginal Fermi liquid offers clues about the microscopic origin of the anomalous fluctuations as well, as we find that the antiferromagnetic model is the [ital minimal] [ital model] capable of supporting a fixed line of the scaling equations, making it a promising candidate for the microscopic foundation of high-temperature superconductivity.

  7. Proprietes Adiabatiques des Naines Blanches Pulsantes de Type ZZ Ceti

    NASA Astrophysics Data System (ADS)

    Brassard, Pierre

    1992-01-01

    Cette these a pour but d'etudier les proprietes des oscillation non-radiales des etoiles ZZ Ceti, appelees aussi etoiles DA variables, dans le contexte de la theorie adiabatique des petites oscillations. Ces oscillations sont observables, pour ce type d'etoiles, sous forme de variations periodiques de la luminosite. A partir d'une analyse de modeles stellaires, analyse qui consiste principalement a calculer et a interpreter les periodes d'oscillations des modeles, nous voulons mieux connai tre les proprietes physiques fondamentales des ZZ Ceti. Nous developpons tout d'abord divers outils pour entreprendre cette etude. Apres avoir presente le formalisme mathematique de base decrivant les oscillations non-radiales d'une etoile, nous discutons des difficultes pouvant etre rencontrees dans le calcul de la frequence de Brunt-Vaisala, une quantite fondamentale pour le calcul des periodes d'oscillations. Par la suite, nous developpons un modele theorique simple permettant d'analyser et d'interpreter la structure des periodes calculees (ou observees) en termes des proprietes de structure de l'etoile. Nous presentons aussi les outils numeriques tout a fait originaux utilises pour calculer nos periodes a partir de modeles stellaires. Finalement, nous presentons les resultats d'ensemble de l'analyse de nos modeles, et discutons de l'interpretation des observations de periodes et du taux de variation de ces periodes en termes de structure de l'etoile et de composition du noyau de l'etoile, respectivement. Ces resultats representent l'etude la plus complete a ce jour de la seismologie des naines blanches.

  8. Etude des phenomenes dynamiques ultrarapides et des caracteristiques impulsionnelles d'emission terahertz du supraconducteur YBCO

    NASA Astrophysics Data System (ADS)

    Savard, Stephane

    Les premieres etudes d'antennes a base de supraconducteurs a haute temperature critique emettant une impulsion electromagnetique dont le contenu en frequence se situe dans le domaine terahertz remontent a 1996. Une antenne supraconductrice est formee d'un micro-pont d'une couche mince supraconductrice sur lequel un courant continu est applique. Un faisceau laser dans le visible est focalise sur le micro-pont et place le supraconducteur dans un etat hors-equilibre ou des paires sont brisees. Grace a la relaxation des quasiparticules en surplus et eventuellement de la reformation des paires supraconductrices, nous pouvons etudier la nature de la supraconductivite. L'analyse de la cinetique temporelle du champ electromagnetique emis par une telle antenne terahertz supraconductrice s'est averee utile pour decrire qualitativement les caracteristiques de celle-ci en fonction des parametres d'operation tels que le courant applique, la temperature et la puissance d'excitation. La comprehension de l'etat hors-equilibre est la cle pour comprendre le fonctionnement des antennes terahertz supraconductrices a haute temperature critique. Dans le but de comprendre ultimement cet etat hors-equilibre, nous avions besoin d'une methode et d'un modele pour extraire de facon plus systematique les proprietes intrinseques du materiau qui compose l'antenne terahertz a partir des caracteristiques d'emission de celle-ci. Nous avons developpe une procedure pour calibrer le spectrometre dans le domaine temporel en utilisant des antennes terahertz de GaAs bombarde aux protons H+ comme emetteur et detecteur. Une fois le montage calibre, nous y avons insere une antenne emettrice dipolaire de YBa 2Cu3O7-delta . Un modele avec des fonctions exponentielles de montee et de descente du signal est utilise pour lisser le spectre du champ electromagnetique de l'antenne de YBa 2Cu3O7-delta, ce qui nous permet d'extraire les proprietes intrinseques de ce dernier. Pour confirmer la validite du modele choisi, nous avons mesure les proprietes intrinseques du meme echantillon de YBa2Cu3O7- delta avec la technique pompe-visible et sonde-terahertz donnant, elle aussi, acces aux temps caracteristiques regissant l'evolution hors-equilibre de ce materiau. Dans le meilleur scenario, ces temps caracteristiques devraient correspondre a ceux evalues grace a la modelisation des antennes. Un bon controle des parametres de croissance des couches minces supraconductrices et de fabrication du dispositif nous a permis de realiser des antennes d'emission terahertz possedant d'excellentes caracteristiques en terme de largeur de bande d'emission (typiquement 3 THz) exploitables pour des applications de spectroscopie resolue dans le domaine temporel. Le modele developpe et retenu pour le lissage du spectre terahertz decrit bien les caracteristiques de l'antenne supraconductrice pour tous les parametres d'operation. Toutefois, le lien avec la technique pompe-sonde lors de la comparaison des proprietes intrinseques n'est pas direct malgre que les deux techniques montrent que le temps de relaxation des porteurs augmente pres de la temperature critique. Les donnees en pompe-sonde indiquent que la mesure du temps de relaxation depend de la frequence de la sonde, ce qui complique la correspondance des proprietes intrinseques entre les deux techniques. De meme, le temps de relaxation extrait a partir du spectre de l'antenne terahertz augmente en s'approchant de la temperature critique (T c) de YBa2Cu 3O7-delta. Le comportement en temperature du temps de relaxation correspond a une loi de puissance qui est fonction de l'inverse du gap supraconducteur avec un exposant 5 soit 1/Delta 5(T). Le travail presente dans cette these permet de mieux decrire les caracteristiques des antennes supraconductrices a haute temperature critique et de les relier aux proprietes intrinseques du materiau qui les compose. De plus, cette these presente les parametres a ajuster comme le courant applique, la puissance de la pompe, la temperature d'operation, etc, afin d'optimiser l'emission et les performances de ces

  9. Redox chemistry at liquid/liquid interfaces

    NASA Technical Reports Server (NTRS)

    Volkov, A. G.; Deamer, D. W.

    1997-01-01

    The interface between two immiscible liquids with immobilized photosynthetic pigments can serve as the simplest model of a biological membrane convenient for the investigation of photoprocesses accompanied by spatial separation of charges. As it follows from thermodynamics, if the resolvation energies of substrates and products are very different, the interface between two immiscible liquids may act as a catalyst. Theoretical aspects of charge transfer reactions at oil/water interfaces are discussed. Conditions under which the free energy of activation of the interfacial reaction of electron transfer decreases are established. The activation energy of electron transfer depends on the charges of the reactants and dielectric permittivity of the non-aqueous phase. This can be useful when choosing a pair of immiscible solvents to decrease the activation energy of the reaction in question or to inhibit an undesired process. Experimental interfacial catalytic systems are discussed. Amphiphilic molecules such as chlorophyll or porphyrins were studied as catalysts of electron transfer reactions at the oil/water interface.

  10. Liquid lubrication in space

    NASA Technical Reports Server (NTRS)

    Zaretsky, Erwin V.

    1990-01-01

    The requirement for long-term, reliable operation of aerospace mechanisms has, with a few exceptions, pushed the state of the art in tribology. Space mission life requirements in the early 1960s were generally 6 months to a year. The proposed U.S. space station schedule to be launched in the 1990s must be continuously usable for 10 to 20 years. Liquid lubrication systems are generally used for mission life requirements longer than a year. Although most spacecraft or satellites have reached their required lifetimes without a lubrication-related failure, the application of liquid lubricants in the space environment presents unique challenges. The state of the art of liquid lubrication in space as well as the problems and their solutions are reviewed.

  11. Buckling of Liquid Columns

    NASA Astrophysics Data System (ADS)

    Habibi, M.; Rahmani, Y.; Bonn, Daniel; Ribe, N. M.

    2010-02-01

    Under appropriate conditions, a column of viscous liquid falling onto a rigid surface undergoes a buckling instability. Here we show experimentally and theoretically that liquid buckling exhibits a hitherto unsuspected complexity involving three different modes—viscous, gravitational, and inertial—depending on how the viscous forces that resist bending of the column are balanced. We also find that the nonlinear evolution of the buckling exhibits a surprising multistability with three distinct states: steady stagnation flow, “liquid rope coiling,” and a new state in which the column simultaneously folds periodically and rotates about a vertical axis. The transitions among these states are subcritical, leading to a complex phase diagram in which different combinations of states coexist in different regions of the parameter space.

  12. Alloying of liquid aluminum

    SciTech Connect

    Shafyei, A.; Guthrie, R.I.L.

    1996-10-01

    The addition of high melting point alloying elements is an integral component in the processing of molten aluminum alloys. In this research, the kinetics of dissolution of manganese and iron particles, freely dispersed in turbulently-stirred baths of liquid aluminum, has been investigated at a laboratory scale. First, the suspension behavior of alloying elements in liquid aluminum was studied via water modeling analogues, using dimensional analysis and similarity techniques. Second, mass transfer coefficients between particles of manganese or iron and stirred liquid aluminum were measured. These high temperature experiments showed that measured mass transfer coefficients of manganese and iron particles were strongly dependent on the intensity of the mixing, until the point at which particles became fully suspended. Further increases in the rate of mixing produced little further rises in mass transfer coefficients. From a practical point of view, therefore, these results suggested that very high rates of melt mixing are not recommended during an alloying process.

  13. La modelisation mathematique dans l'enseignement de la chimie des gaz a des eleves de la cinquieme annee du secondaire

    NASA Astrophysics Data System (ADS)

    Gauthier, Diane

    Les problemes d'enseignement de la chimie des gaz parfaits sont donc importants. Si plusieurs etudes ont ete realisees dans le but d'identifier et d'interpreter ces problemes, aucune recherche, a notre connaissance, n'a ete realisee sur l'enseignement des lois sur les gaz parfaits. Notre recherche sur l'enseignement est donc pionniere. Elle a pour objectif general de construire et d'analyser une sequence d'enseignement de la chimie des gaz comportant diverses situations de modelisation mathematique des conduites des gaz. Les principaux objectifs specifiques sont les suivants: (1) identifier et caracteriser les situations qui provoquent une evolution des conceptions naives des eleves, evolution vers des connaissances plus adequate sur les gaz; (2) identifier et caractEriser les situations qui provoquent une evolution des connaissances mathematiques des eleves leur permettant d'interpreter convenablement les resultats des experiences, d'eprouver leurs conceptions, de donner un sens aux notions et aux relations impliquees dans les lois des gaz parfaits, lois de Boyle-Mariotte et Gay-Lussac. Une sequence d'enseignement comportant huit situations est d'eleves de secondaire V. La construction de ces situations est orientee par les recherches sur les conceptions naives des eleves, par les etudes sur l'evolution historique des conceptions sur les gaz et des pratiques scientifiques, ainsi que par les etudes theoriques et empiriques realisees en didactique des sciences et des mathematiques. La methodologie de l'ingenierie didactique (Artigue, 1998) qui constitue une application de la theorie des situations didactiques (Brousseau, 1986) est utilisee dans la construction et l'analyse des situations d'enseignement. Une analyse a priori de chacune des situations d'enseignement est effectuee; elle a pour but dexpliquer les choix des taches qui font partie des situations et de preciser la gestion didactique des situations. Diverses situations d'enseignement de la chimie ont ainsi ete construites. L'analyse a posteriori des situations, analyse des interactions didactiques lors du deroulement en classe de ces situations, est confrontee a l'analyse a priori realisee lors de la construction de ces situations. La pertinence de ces situations est ainsi examinee, en regard des objectifs de la recherche. (Abstract shortened by UMI.)

  14. Traitement des séquelles de brûlures de la main dans les pays à ressources limitées ; notre expérience en république démocratique du Congo

    PubMed Central

    Kibadi, K.; Moutet, F.

    2015-01-01

    Summary Les séquelles de brûlures de la main sont encore fréquentes dans les pays à ressources limitées. Trente-deux patients, représentant 38 mains, ont été admis et traités, entre le 1er décembre 2010 et le 1er mai 2014 aux Cliniques Universitaires de Kinshasa en République Démocratique du Congo (RDC). nous avons observé 22 patients (69 %) dans le groupe de jeunes (patients âgés de moins de 18 ans), et 10 patients (31 %) chez les adultes (18 à 59 ans). Aucun patient dans le groupe de seniors (60 ans et plus) n’a été observé. Dans le groupe de jeunes, la tranche d’âge de 1 à 5 ans a été la plus atteinte avec 13 malades (40 %). l’accident à la maison était le plus fréquent (72 %). le mécanisme de la brûlure était le plus souvent thermique par flammes (51 %) ou par liquide chaud (34 %). les rétractions et brides sont les lésions le plus observées (84 %). la rétraction dorsale globale « main en griffe» est observée chez 40 % de patients traités, associée à des cicatrices hypertrophiques et chéloïdiennes dans 84 % de cas. Chez les 32 mains traitées chirurgicalement, des excision-greffes ont été réalisées dans 43,7 %, des lambeaux locaux dans 43,7 % et des lambeaux à distance dans 12,5 % de cas. A la sortie de l’hôpital, 84 % de « bons » résultats ont été observés. le suivi a été de 18 mois. le traitement des séquelles de brûlures de la main est possible dans ces pays, exemple de la rDC. Mais les défis à surmonter dans ces pays sont nombreux : la faible accessibilité aux techniques actuelles de la chirurgie plastique, la prise en charge initiale inadéquate des brûlures, la pauvreté. PMID:26668560

  15. Liquid metal fuel combustion mechanics

    NASA Astrophysics Data System (ADS)

    Duvvuri, Tirumalesa

    1990-07-01

    The modeling of the droplet formation at the gas/liquid boundary interface of a gaseous jet injected into a liquid metal bath and the turbulent mixing of the resultant two-phase (gas/liquid) mixture is presented as a preliminary to the analysis of the liquid metal fuel combustion problem. The model is used to predict velocity and liquid droplet fraction distributions across the mixing zone and along the centerline of the jet. These results show that the distribution of the liquid fuel droplets peaks away from the region of maximum oxidizer concentrations.

  16. Turbine meters for liquid measurement

    SciTech Connect

    Wass, D.J.; Allen, C.R.

    1995-12-01

    Liquid turbine meters operate in response to fundamental engineering principles, Operation with a single moving part produces excellent longevity and reliability. Liquid turbine meters display wide rangeability, high accuracy, excellent repeatability, low pressure drop and moderate cost. Liquid turbine meters may be applied to many different fluids with different physical properties and corrosive tendencies. The marriage of liquid turbine meters to electronic instruments allows instantaneous flow calculations and produces the flexibility to display data, store data, transmit data in the most convenient form. Liquid turbine meters should be the first flow measurement instrument considered for liquid measurement applications.

  17. Liquid fuel developments

    SciTech Connect

    Wise, D.L.; Carreira, L.H.; Ljungdahl, L.G.

    1983-01-01

    This book concerns the biosynthesis of ethanol fuels from biomass. Topics considered include anaerobic thermophilic bacteria, screening for cellulolytic mutants, the enzymatic hydrolysis of cellulose to fermentable sugars, process biotechnology for the conversion of biomass into liquid fuels, a flow reactor for acid hydrolysis or pretreatment of cellulosic biomass, the production of ethanol and chemicals from wood by the Georgia Tech process, liquid fuels and chemicals from cellulosic residues by acid hydrolysis, alkane fuels production from biomass, and the integration of production of corn-derived fuels with animal feed production.

  18. Liquid metal pump

    DOEpatents

    Pennell, William E. (Greensburg, PA)

    1982-01-01

    The liquid metal pump comprises floating seal rings and attachment of the pump diffuser to the pump bowl for isolating structural deflections from the pump shaft bearings. The seal rings also eliminate precision machining on large assemblies by eliminating the need for a close tolerance fit between the mounting surfaces of the pump and the seals. The liquid metal pump also comprises a shaft support structure that is isolated from the pump housing for better preservation of alignment of shaft bearings. The shaft support structure also allows for complete removal of pump internals for inspection and repair.

  19. Liquid metal pump

    SciTech Connect

    Pennell, W.E.

    1982-11-23

    The liquid metal pump comprises floating seal rings and attachment of the pump diffuser to the pump bowl for isolating structural deflections from the pump shaft bearings. The seal rings also eliminate precision machining on large assemblies by eliminating the need for a close tolerance fit between the mounting surfaces of the pump and the seals. The liquid metal pump also comprises a shaft support structure that is isolated from the pump housing for better preservation of alignment of shaft bearings. The shaft support structure also allows for complete removal of pump internals for inspection and repair.

  20. Improved Capacitive Liquid Sensor

    NASA Technical Reports Server (NTRS)

    Waldman, Francis A.

    1992-01-01

    Improved capacitive sensor used to detect presence and/or measure thickness of layer of liquid. Electrical impedance or admittance of sensor measured at prescribed frequency, and thickness of liquid inferred from predetermined theoretical or experimental relationship between impedance and thickness. Sensor is basically a three-terminal device. Features interdigitated driving and sensing electrodes and peripheral coplanar ground electrode that reduces parasitic effects. Patent-pending because first to utilize ground plane as "shunting" electrode. System less expensive than infrared, microwave, or refractive-index systems. Sensor successfully evaluated in commercial production plants to characterize emulsions, slurries, and solutions.