Sample records for liquids hydroformylation des

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

    SciTech Connect

    Yonker, Clement R. (BATTELLE (PACIFIC NW LAB)); Linehan, John C. (BATTELLE (PACIFIC NW LAB))

    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. [Argonne National Lab., IL (United States)

    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. 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.

  6. 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

  7. 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.

  8. 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

  9. 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.

  10. 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.

  11. Evolution of hydroformylation chemistry

    SciTech Connect

    Slaugh, L.H. [Shell Development Co., Houston, TX (United States)

    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.

  12. 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.

  13. 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.

  14. Regioselective Hydroformylation of Allylic Alcohols

    PubMed Central

    Lightburn, Thomas E.; De Paolis, Omar A.; Cheng, Ka H.; Tan, Kian L.

    2011-01-01

    A highly regioselective hydroformylation of allylic alcohols is reported towards the synthesis of ?-hydroxy-acid and aldehyde products. The selectivity is achieved through the use of a ligand that reversibly binds to alcohols in situ, allowing for a directed hydroformylation to occur. The application to trisubstituted olefins was also demonstrated, which yields a single diastereomer product consistent with a stereospecific addition of CO and hydrogen. PMID:21504208

  15. Enantioselective Hydroformylation of Aniline Derivatives

    PubMed Central

    Joe, Candice L.; Tan, Kian L.

    2011-01-01

    We have developed a ligand that reversibly binds to aniline substrates allowing for the control of regioselectivity and enantioselectivity in hydroformylation. In this paper we address how the electronics of the aniline ring affect both binding of the substrate to the ligand and the enantioselectivity in this reaction. PMID:21842847

  16. 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

  17. 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

    Accurate knowledge of the phase equilibria of CO2-expanded hydroformylation reaction mixtures is essential to rational process design and development. Vapor liquid equilibria of the following systems were measured in a variable volume view cell...

  18. 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 ...

  19. 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.

  20. 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.

  1. 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

  2. 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

  3. 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

  4. 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

  5. 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

  6. 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

  7. 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. (Virginia Polytechnic Institute and State Univ., Blacksburg (USA))

    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.

  8. 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.…

  9. 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 phosphorus ligand has been prepared starting from chiral NOBIN (2-amino-2- hydroxy-1,1-binaphthyl). Excellent phosphorus ligands bearing two different phosphorus groups are effective in asymmetric hydroformylation.2a

  10. 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.

  11. Kinetics and dynamics of heterogeneous hydroformylation Rh catalysts

    SciTech Connect

    Chuang, S.S.C.; Brundage, M.A.; Balakos, M.W. [Univ. of Akron, OH (United States)

    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.

  12. ORIGINAL PAPER Gas-Phase Hydroformylation of Propene over Silica-Supported

    E-print Network

    Iglesia, Enrique

    ORIGINAL PAPER Gas-Phase Hydroformylation of Propene over Silica-Supported PPh3-Modified Rhodium Hydroformylation Á Butanal Á Heterogeneous Á Rhodium Á Silica Á Supported 1 Introduction Aldehydes are produced industrially by hydroformylation of olefins with synthesis gas. Homogeneous complexes of Rh and Co

  13. Hydroformylation catalyzed by immobilized rhodium complex to polymer support

    SciTech Connect

    Yoneda, N.; Nakagawa, Y.; Mimami, T. [Chiyoda Corp., Yokohama (Japan)

    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.

  14. 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.

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

    SciTech Connect

    Katsnel`son, M.G.; Kagna, S.Sh.; Beilin, L.B. [All-Union Scientific Research Inst. of Petrochemical Processes, St. Petersburg (Russian Federation)

    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.

  16. Hydroformylation in aqueous biphasic media assisted by molecular receptors.

    PubMed

    Hapiot, Frédéric; Bricout, Hervé; Tilloy, Sébastien; Monflier, Eric

    2013-01-01

    The role of molecular receptors in aqueous biphasic hydroformylation of higher olefins is highlighted through a detailed analysis of their molecular recognition properties. The behavior of cyclodextrins and calixarenes as molecular receptors is especially emphasized and discussed. Their supramolecular interactions with the substrates and the water-soluble ligands proved to be an essential parameter guiding the reaction performances. The hydroformylation activity and chemo- and regio-selectivities can thus be accurately controlled by a suitable match between the receptor and the reaction components. Development outlooks are also presented. PMID:23563584

  17. 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

  18. 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

  19. 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

  20. 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

  1. D o s s i e r Discovery and Optimization of Catalysis and Solvents for Absorption Using High Throughput Experimentation

    E-print Network

    Paris-Sud XI, Université de

    débit Cobalt Hydroformylation of Olefins in a Biphasic System Using Ionic Liquids ­ Development.olivier-bourbigou@ifpen.fr * Corresponding author Re´ sume´ -- Hydroformylation des ole´ fines par le cobalt en milieu liquide ionique ­ De le de´ veloppement et l'optimisation de la re´ action d'hydroformylation des ole´ fines par le cobalt

  2. 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

  3. 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

  4. Hydroformylation of C 8 olefins catalyzed by rhodium–inorganic ammonium salt systems

    Microsoft Academic Search

    Dehua He; Dongcheng Pang; Lan Wei; Yu Chen; Tong-en Wang; Zhigang Tang; Jinyao Liu; Ye Liu; Qiming Zhu

    2002-01-01

    The effect of inorganic ammonium salts which contain group VIB metals of the periodic table (ammonium chromate, ammonium dichromate, ammonium molybdate and ammonium tungstate) as additives on the catalytic performance of Rh catalysts for the hydroformylation of C8-olefins and 1-dodecylene has been investigated. Modification of rhodium with ammonium salts could increase the yield of aldehydes in the hydroformylation of the

  5. 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

  6. Vitesse de passage des rsidus alimentaires et des liquides dans le tube digestif du mouton

    E-print Network

    Paris-Sud XI, Université de

    différents types de marqueurs : oxyde de chrome mordancé (Cr- mord.) ou imprégné sur poudre de cellulose (Cr le Cr-mord. (tabi. 11. Les différences entre marqueurs apparaissent essentiel- lement au niveau des du temps de séjour moyen doit être intermédiaire entre celle du Cr- mord et celles du Cr-cell ou de l

  7. Transonic liquid bells Laboratoire de Physique et Mecanique des Milieux Heteroge`nes--UMR 7636 CNRS Ecole

    E-print Network

    Brunet, Philippe

    Transonic liquid bells P. Brunet Laboratoire de Physique et Me´canique des Milieux He´te´roge`nes, France C. Clanet Institut de Recherche sur les Phe´nome`nes Hors Equilibre--UMR 6594, Technopo^le de Cha Physique et Me´canique des Milieux He´te´roge`nes--UMR 7636 CNRS Ecole Supe´rieure de Physique et Chimie

  8. 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.

  9. In situ spectroscopic studies in hydroformylation of olefins

    SciTech Connect

    Horvath, I.T. [Exxon Research & Engineering Co., Annandale, NJ (United States)

    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. 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

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

    SciTech Connect

    Koch, H.F.; Misquitta, B.J.; Stanley, G.G. [Louisiana State Univ., Baton Rouge, LA (United States)

    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}.

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

    SciTech Connect

    Imyanitov, N.S.; Tupitsyn, S.B. [VNIINeftekhim, St Petersburg (Russian Federation)

    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.

  13. 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

  14. Biphasic hydroformylation of olefins using a novel water soluble rhodium polyethylene glycolate catalyst

    Microsoft Academic Search

    Thomas Borrmann; Herbert W. Roesky; Uwe Ritter

    2000-01-01

    The highly reactive water-soluble hydroformylation catalyst, rhodium polyethylene glycolate (Rh(PEG)x), prepared by the reaction of polyethylene glycol and rhodium trichloride hydrate, was used as a catalyst for hydroformylation reactions of olefins, such as dodec-1-ene, 2.4.4-trimethylpent-1-ene and styrene, in biphasic systems. The reactions were done in a broad temperature range and at a pressure range from 7 to 12 MPa. Turnover

  15. 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

  16. 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

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

    SciTech Connect

    Korneyeva, G.A.; Chekhova, R.V.; Potarin, M.M. [A.V. Topchiyev Institute of Petrochemical Synthesis, Moscow (Russian Federation)

    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.

  19. 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. [Univ. of Ottawa, Ontario (Canada)

    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.

  20. Co-Co2C and Co-Co2C/AC Catalysts for Hydroformylation of 1Hexene under Low Pressure: Experimental and Theoretical Studies

    E-print Network

    Li, Weixue

    Co-Co2C and Co-Co2C/AC Catalysts for Hydroformylation of 1Hexene under Low Pressure: Experimental been first proven to be highly active for 1-hexene hydroformylation under low pressure (P = 3.0 MPa a highly catalytic stability for 1-hexene hydroformylation with a time stream of 140 h, indicating

  1. 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

  2. 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.

  3. Dynamic and LHHW kinetic analysis of heterogeneous catalytic hydroformylation

    SciTech Connect

    Balakos, M.W.; Chuang, S.S.C. [Univ. of Akron, OH (United States)] [Univ. of Akron, OH (United States)

    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.

  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. Phosphabenzenes as monodentate pi-acceptor ligands for rhodium-catalyzed hydroformylation.

    PubMed

    Breit, B; Winde, R; Mackewitz, T; Paciello, R; Harms, K

    2001-07-16

    A new class of phosphinine/rhodium catalysts for the hydroformylation of terminal and internal alkenes is presented in this study. A series of phosphabenzenes 1-14 has been prepared by condensation of phosphane or tris(trimethylsilyl)phosphane with the corresponding pyrylium salt. Trans-[(phosphabenzene)2RhCl(CO)] complexes 21-25 have been prepared and studied spectroscopically and by X-ray crystal-structure analysis. The hydroformylation of oct-1-ene has been used to identify optimal catalyst preformation and reaction conditions. Hydroformylation studies with 15 monophosphabenzenes have been performed. The catalytic performance is dominated by steric influences, with the phosphabenzene 8/rhodium system being the most active catalyst. Turnover frequencies of up to 45370 h(-1) for the hydroformylation of oct-1-ene have been determined. In further studies, hydroformylation activity toward more highly substituted alkenes was investigated and compared with the standard industrial triphenylphosphane/rhodium catalyst. The reactivity differences between the phosphabenzene and the triphenylphosphane catalyst increase on going to the more highly substituted alkenes. Even tetrasubstituted alkenes reacted with the phosphabenzene catalyst, whereas the triphenylphosphane system failed to give any product. In situ pressure NMR experiments have been performed to identify the resting state of the catalyst. A monophosphabenzene complex [(phosphinine 8)Ir(CO)3H] could be detected as the predominant catalyst resting state. PMID:11495438

  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. [and others

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

    SciTech Connect

    Hong, L.; Ruckenstein, E. (State Univ. of New York, Buffalo, NY (United States))

    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.

  9. Hydroformylation of 1-heptene catalyzed by ruthenium cluster

    SciTech Connect

    Li, Z.; Zhang, J.; Wang, C. [Taiyuan Univ. of Technology (China). Inst. of Coal Chemical Engineering

    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.

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

    SciTech Connect

    Horvath, I.T.; Rabai, J. [Exxon Research and Engineering Co., Annandale, NJ (United States)

    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. Tandem hydroformylation/hydrogenation of alkenes to normal alcohols using Rh/Ru dual catalyst or Ru single component catalyst.

    PubMed

    Takahashi, Kohei; Yamashita, Makoto; Nozaki, Kyoko

    2012-11-14

    The catalyst system for tandem hydroformylation/hydrogenation of terminal alkenes to the corresponding homologated normal alcohol was developed. The reaction mechanism for the Rh/Ru dual catalyst was investigated by real-time IR monitoring experiments and (31)P NMR spectroscopy, which proved the mutual orthogonality of Rh-catalyzed hydroformylation and Ru-catalyzed hydrogenation. Detailed investigation about Ru-catalyzed hydrogenation of undecanal under H(2)/CO pressure clarified different kinetics from the hydrogenation under H(2) and gave a clue to design more active hydrogenation catalysts under H(2)/CO atmosphere. The solely Ru-catalyzed normal selective hydroformylation/hydrogenation is also reported. PMID:23116366

  12. 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.

  13. 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

  14. 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

  15. 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

  16. 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

  17. 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

  18. 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

  19. 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.

  20. 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.

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

    SciTech Connect

    Tsoy, A.A.; Kayumov, F.F.; Grudtsyn, Yu.D. [Scientific Research and Design Inst. of Monomers, Tula (Russian Federation)] [and others

    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.

  2. 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

  3. 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.

  4. Recovery of solubilized rhodium from hydroformylated vegetable oils and their methyl esters

    Microsoft Academic Search

    E. J. Dufek; G. R. List

    1977-01-01

    and summary  Procedures were developed to extract rhodium from hydroformylated vegetables oils and methyl esters. Among the numerous reagents\\u000a surveyed, aqueous hydrogen cyanide with triethanolamine (TEA) was found to be most effective. The effects of time, temperature,\\u000a and concentration of reagents were studied. Over 98% of the solubilized rhodium was removed from crude methyl formylstearate\\u000a at 100 C for 1 hr

  5. 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

  6. 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

  7. Spiroketal-based phosphorus ligands for highly regioselective hydroformylation of terminal and internal olefins.

    PubMed

    Jia, Xiaofei; Wang, Zheng; Xia, Chungu; Ding, Kuiling

    2012-11-26

    A new class of bidentate phosphoramidite ligands, based on a spiroketal backbone, has been developed for the rhodium-catalyzed hydroformylation reactions. A range of short- and long-chain olefins, were found amenable to the protocol, affording high catalytic activity and excellent regioselectivity for the linear aldehydes. Under the optimized reaction conditions, a turnover number (TON) of up to 2.3×10(4) and linear to branched ratio (l/b) of up to 174.4 were obtained in the Rh(I)-catalyzed hydroformylation of terminal olefins. Remarkably, the catalysts were also found to be efficient in the isomerization-hydroformylation of some internal olefins, to regioselectively afford the linear aldehydes with TON values of up to 2.0×10(4) and l/b ratios in the range of 23.4-30.6. X-ray crystallographic analysis revealed the cis coordination of the ligand in the precatalyst [Rh(3d)(acac)], whereas NMR and IR studies on the catalytically active hydride complex [HRh(CO)(2)(3d)] suggested an eq-eq coordination of the ligand in the species. PMID:23135928

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

    SciTech Connect

    Natio, Shuichi (Univ. of Tokyo (Japan)); Tanimoto, Mitsutoshi (Shizuoka Univ. (Japan))

    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.

  9. 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. [A.V. Topchiyev Institute of Petrochemical Synthesis, Moscow (Russian Federation)] [and others

    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.

  10. Hydrogen bonding as a construction element for bidentate donor ligands in homogeneous catalysis: regioselective hydroformylation of terminal alkenes.

    PubMed

    Breit, Bernhard; Seiche, Wolfgang

    2003-06-01

    A new concept for the construction of bidentate ligands for homogeneous metal complex catalysis is described. The concept relies on the self-assembly of monodentate ligands through hydrogen bonding. As a prototype of such systems, 6-diphenylphosphanyl-2-pyridone (6-DPPon) was shown to form a chelate in the coordination sphere of a transition metal center through unusual pyridone/hydroxypyridine hydrogen bonding (X-ray). This hydrogen bonding stays intact in a catalytic reaction as proven upon highly regioselective hydroformylation of terminal alkenes. Regioselectivities and reactivities observed rank the 6-DPPon/rhodium system among the most active and regioselective catalysts for n-selective hydroformylation of terminal alkenes. PMID:12769551

  11. 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

  12. 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. [Univ. of California, Santa Barbara, CA (United States)

    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.

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

    SciTech Connect

    Izumi, Y.; Asakura, K.; Iwasawa Y. (Univ. of Tokyo (Japan))

    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.

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

    SciTech Connect

    Gao, H.; Angelici, R.J. [Iowa State Univ., Ames, IA (United States). Dept. of Chemistry] [Iowa State Univ., Ames, IA (United States). Dept. of Chemistry; [Ames Lab., IA (United States)

    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.

  15. 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

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

    SciTech Connect

    Izumi, Y.; Asakura, K.; Iwasawa, Y. (Univ. of Tokyo (Japan))

    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}.

  17. 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

  18. 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.

  19. 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

  20. 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

  1. 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 (Kitami Institute of Technology (Japan))

    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.

  2. 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

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

    SciTech Connect

    Otsuka, Kiyoshi; Ando, Ten; Yamanaka, Ichiro [Tokyo Institute of Technology, Meguro-ku (Japan)] [Tokyo Institute of Technology, Meguro-ku (Japan)

    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.

  4. Mechanistic insights into a supramolecular self-assembling catalyst system: evidence for hydrogen bonding during rhodium-catalyzed hydroformylation.

    PubMed

    Gellrich, Urs; Seiche, Wolfgang; Keller, Manfred; Breit, Bernhard

    2012-10-29

    The structural integrity and flexibility provided by intermolecular hydrogen bonds leads to the outstanding properties of the 6-diphenylphosphinopyridin-(2H)-1-one ligand (see scheme) in the rhodium-catalyzed hydroformylation of terminal alkenes, as demonstrated by the combination of spectroscopic methods and DFT computations. Hydrogen bonds were also detected in a competent intermediate of the catalytic cycle. PMID:23023718

  5. 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

  6. 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. [Union Carbide Technical Center, South Charleston, WV (United States)

    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.

  7. 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

  8. 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

  9. 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

  10. 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).

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

    SciTech Connect

    Brundage, M.A.; Chuang, S.S.C. [Univ. of Akron, OH (United States)] [Univ. of Akron, OH (United States)

    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.

  12. Isomerizing hydroformylation of trans-4-octene to n-nonanal in multiphase systems: acceleration effect of propylene carbonate

    Microsoft Academic Search

    Arno Behr; Dietmar Obst; Barbara Turkowski

    2005-01-01

    In this contribution we present the isomerizing hydroformylation of trans-4-octene to n-nonanal in a two-phase catalytic reaction system. Based on this two-phase system, the application of a thermomorphic multi-solvent catalytic reaction system will be presented which changes from a two-phase to a single-phase system by simply raising the temperature. This concept provides the possibility to overcome mass transport limitations which

  13. 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

  14. 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. [Laboratoire de Catalyse Heterogene et Homogene, Villeneuve d` Ascq (France)] [and others] [Laboratoire de Catalyse Heterogene et Homogene, Villeneuve d` Ascq (France); and others

    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.

  15. 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.

  16. 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. [A.V. Topchiev Inst. of Petrochemical Synthesis, Moscow (Russian Federation)] [and others

    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.

  17. 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

  18. 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.

  19. 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

  20. 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

  1. 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. [Universitat de Barcelona, Tarragona (Spain)] [and others

    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.

  2. 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

  3. 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

  4. 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

  5. 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

  6. 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

  7. 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. (Univ. of Akron, OH (United States))

    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.

  8. 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.

  9. 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

  10. 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

  11. 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.

  12. 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. [Univ. of Wisconsin, Madison, WI (United States)] [and others

    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.

  13. 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

  14. 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

  15. 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 [Takasago International Corp., Kanagawa (Japan)] [and others

    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.

  16. Colmatage des réacteurs gaz liquide à lit fixePlugging in two-phase flow packed beds

    NASA Astrophysics Data System (ADS)

    Iliuta, Ion; Larachi, Fa??çal

    A 1-D transient two-fluid deep-bed filtration model was formulated for the capture of colloidal fines in porous media experiencing gas-liquid trickling and dispersed bubble flow regimes. The deposit prediction resulted from solving the coupled volume-average fines' advection-dispersion, Navier-Stokes, volume and mass conservation equations for the three phases. To make the system solvable, it was augmented by auxiliary closures expressing the coupling between fluids and porous medium via the drag interfacial forces, the filter coefficient in the so-called mono- and multi-layer modes, and the growth of the specific surface area of the filter bed for liquid-solid drag. To cite this article: I. Iliuta, F. Larachi, C. R. Mecanique 330 (2002) 563-568.

  17. Influence des parametres hydrodynamiques sur le transfert de matiere dans un liquide en ecoulement pulsé dans une cathode cylindrique

    Microsoft Academic Search

    A. Gadri; A. Ratel; G. Lacoste

    1998-01-01

    L'étude de transfert de matière dans un liquide traversant un tube cylindrique sous un régime d'écoulement pulsé a été d'abord menée expérimentalement pour différentes valeurs de paramètres caractérisant les conditions hydrodynamiques et en mettant en oeuvre a réduction électrochimique de l'ion ferricyanure à une électrode de nickel dans la soude 1m. L'expérience montre que la surimposition de la pulsation à

  18. 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. (Korea Advanced Institute of Science and Technology, Taejon (Korea, Democratic People's Republic of))

    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.

  19. 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 [Hokkaido Univ., Sapporo (Japan)] [Hokkaido Univ., Sapporo (Japan)

    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.

  20. 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

  1. 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

  2. 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 (Jilin Univ., Changchun (China)); Ichikawa, Masaru (Hokkaido Univ., Sapporo (Japan))

    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.

  3. 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

  4. 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.

  5. 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

  6. 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

  7. Donnees experimentales sur la diffusion des elements majeurs entre verres ou liquides de compositions basaltique, rhyolitique et phonolitique, entre 900°C et 1300°C, a pression ordinaire

    Microsoft Academic Search

    Chantal Alibert; Jean-Paul Carron

    1980-01-01

    Un processus expérimental de diffusion entre cylindres coaxiaux a permis d'analyser à la microsonde électronique les profils de diffusion des éléments Si, Ti, Al, Na, K, Ca, Mg, Fe entre trois couples de matériaux provenant de la fusion de roches naturelles de compositions basaltique, rhyolitique et phonolitique. Les coefficients de diffusion calculés sont très voisins pour tous les cations et

  8. 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. (Univ. of Joensuu (Finland))

    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.

  9. 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. [A.V. Topchiev Inst. of Petrochemical Synthesis, Moscow (Russian Federation)] [and others

    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.

  10. 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

  11. Table des mati`eres Introduction 5

    E-print Network

    Paris-Sud XI, Université de

    Table des mati`eres Introduction 5 1 Le verre et l'alt´eration des verres 9 1.1 Le verre et les verres d'aluminosilicate de calcium . . . . . . . . . . . . . . . . 9 1.1.1 L'´etat vitreux . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 1.1.2 Le verre obtenu `a partir d'un liquide . . . . . . . . . . . . . . . . . . . 11 1.1.3 Propri

  12. Liquid-liquid equilibria for the ternary system (phosphonium based deep eutectic solvent-benzene-hexane) at different temperatures: A new solvent introduced

    Microsoft Academic Search

    Mukhtar A. Kareem; Farouq S. Mjalli; M. A. Hashim; Inas M. AlNashef

    2012-01-01

    In this work we studied the applicability of one ionic liquid analogues namely phosphonium based deep eutectic solvent (DES) in the extraction of aromatic hydrocarbons from aromatic\\/aliphatic mixtures. Experimental data for liquid-liquid equilibria (LLE) were obtained for various mixtures of (benzene. +. hexane. +. DES) at 27, 35 and 45 °C. Some of the mixtures showed excellent results in terms

  13. Etude Experimentale et Modelisation des Equilibres Solide—Liquide du Systeme Binaire H 2 O—UO 2 (NO 3 ) 2

    Microsoft Academic Search

    R. Tenu; S. Gentil; S. Baudu; J. J. Counioux

    1999-01-01

    The binary system H2O—UO2(NO3)2 was studied by solubility measurements and constant heat flow thermal analysis. Temperature and composition of the eutectic transformation between ice and uranyl nitrate hexahydrate were accurately defined. A new hydrate with 24 molecules of water decomposes at –21°C according to the peritectoid reaction2(NO3)2·24H2O> 2(NO3)2·6H2O> + 182O>The quasi-ideal model was applied to the solid—liquid equilibria, using the

  14. Prsente pour obtenir le titre de DOCTEUR DE L'ECOLE POLYTECHNIQUE

    E-print Network

    Paris-Sud XI, Université de

    . Synthèse de complexes 5 d'anions de phosphinine : application en hydroformylation des alcènes. 104 1) Introduction bibliographique : le ligand phosphinine en catalyse d'hydroformylation 104 2) Synthèse de

  15. Determination of Estrogens in Water Samples by Ionic Liquid-Based Dispersive Liquid-Liquid Microextraction Combined with High Performance Liquid Chromatography

    Microsoft Academic Search

    Cui-Qin Wu; Di-Yun Chen; Yin-Si Feng; Hong-Mei Deng; Yong-Hui Liu; Ai-Ju Zhou

    2012-01-01

    Using 1-hexyl-3-methylimidazolium hexafluorophosphate ([C6MIM][PF6]) ionic liquid as extraction solvent, five estrogens including estrone (E1), 17?-estradiol (E2), estriol (E3), 17? -ethynylestradiol (EE2), and diethylstilbestrol (DES) in water samples were determined by dispersive liquid-liquid microextraction (DLLME) followed by high performance liquid chromatography with a photodiode array detector and a fluorescence detector (HPLC-DAD-FLD). The extraction procedure was induced by the formation of cloudy

  16. Sociologie des prenoms... des chiens Baptiste Coulmont

    E-print Network

    Paris-Sud XI, Université de

    Sociologie des pr´enoms... des chiens Baptiste Coulmont 23 septembre 2011 Introduction L'´etude de donn´ees concernant plus de 10 millions de chiens (ann´ee de naissance, pr´enom, d´epartement de naissance, race), nous donne les infor- mations suivantes : 1. Les pr´enoms des chiens suivent des modes sp

  17. 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…

  18. Bordereau des Prix Unitaires produits proposs

    E-print Network

    Paris 7 - Denis Diderot, Université

    Bordereau des Prix Unitaires produits proposés produits conditionnement unité Hélium liquide 65 L Prix HT en euros Prix TTC en euros Cette liste n'est pas exhaustive. L'ESPCI PARISTECH peut commander seront inclus dans les prix du tableaux ci- dessus conditionn ement Prix HT en euros Prix TTC en euros

  19. 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. [Indiana Univ., Bloomington, IN (United States)] [and others

    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 +}.

  20. Journes Filtration des Arosols NANCY 7 & 8 juin 2007

    E-print Network

    Paris-Sud XI, Université de

    1ères Journées Filtration des Aérosols NANCY ­ 7 & 8 juin 2007 C9 / 1 FILTRATION CONTINUE ET résultats d'expériences de filtration d'un aérosol de DiEthylHexylSebaçate par un filtre à fibres à Très. Aérosol liquide, Filtration, Colmatage, Perméance, Modèle INTRODUCTION Les aérosols liquides sont à l

  1. 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.

  2. 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. (Univ. of Akron, OH (United States))

    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.

  3. 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 (Hokkaido Univ., Sapporo (Japan)); Kosugi, Nobuhiro; Kuroda, Haruo; Minai, Yoshitaka; Sakai, Yoichi; Tominaga, Tominaga (Univ. of Tokyo (Japan))

    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.

  4. LA REVUE DE L'EPI N 77 DES IMAGES, DES TROUS ET DES BOSSES DES IMAGES, DES TROUS ET DES BOSSES...

    E-print Network

    Paris-Sud XI, Université de

    images (fixes, car pour les images animées c'est encore une autre histoire, au format ".PCX", 320x200 en 256 couleurs). Qu'allons nous en faire ? Les idées ne manquent pas, car une fois numérisée l'image131 LA REVUE DE L'EPI N° 77 DES IMAGES, DES TROUS ET DES BOSSES DES IMAGES, DES TROUS ET DES BOSSES

  5. Fermi liquids and Luttinger liquids

    Microsoft Academic Search

    H. J. Schulz; G. Cuniberti; P. Pieri

    1998-01-01

    In these lecture notes, the basic physics of Fermi liquids and Luttinger liquids is presented. Fermi liquids are discussed both from a phenomenological viewpoint, in relation to microscopic approaches, and as renormalization group fixed points. Luttinger liquids are introduced using the bosonization formalism, and their essential differences with Fermi liquids are pointed out. Applications to transport effects, the effect of

  6. Facult des arts et des sciences Dpartement de communication

    E-print Network

    Parrott, Lael

    Faculté des arts et des sciences Département de communication Plans de cours cadre Cours des programmes de premier cycle en sciences de la communication Comité des études de premier cycle Adopté par l..................................................................................................................................3 COM 1150 Rédaction en communication 1

  7. 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

  8. Archives participatives Au milieu des ralisations remarquables de mdiation numrique des bibliothques et des

    E-print Network

    Paris-Sud XI, Université de

    Archives participatives Au milieu des réalisations remarquables de médiation numérique des bibliothèques et des musées sur les médias sociaux, les services d'archives ont un positionnement relativement en revanche des projets ambitieux de crowdsourcing, d'« archives participatives » (voir encart

  9. 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

  10. Structure des ADN complmentaires des lactoprotines : application la recherche des gnes et leur localisation chromosomique

    E-print Network

    Paris-Sud XI, Université de

    Structure des ADN complémentaires des lactoprotéines : application à la recherche des gènes et à entrepris. 1) Construction de banques ovine et bovine d ADN complémentaires !ADNcJ. Sélection et identification des clones recombinants contenant les ADN complé- mentaires des ARNm des 6 principales

  11. Diethylstilbestrol (DES) and Cancer

    MedlinePLUS

    ... idiopathic thrombocytopenia purpura between DES-exposed and unexposed women ( 10 ). Studies examining the risk of depression among DES daughters ... statistically significant. Researchers will continue to follow these women to study the risk of infertility. Recent studies have found ...

  12. TUDE DES NIVEAUX DE 3He PAR SPECTROSCOPIE OPTIQUE A TRS BASSE TEMPRATURE

    E-print Network

    Paris-Sud XI, Université de

    -cathode usually cooled by liquid helium below the 03BB-point (~ 1,8 °K). Results are as follows : Raies Thiswork et leur analyse, mais donne directement le dépla- cement isotopique. .20 ENREGISTREMENT DES

  13. Linguistique Des mots et Des hommes

    E-print Network

    Loewith, Robbie

    'applique en cas de conclusion d'un nouveau contrat ou de renouvellement de contrat pour un abonnement Orange éclairage nouveau. Des rubriques variées vous attendent, sur l'activité des chercheurs dans et hors les murs témoigne de cette catastrophe 6 Histoire de l'art A partir d'une vingtaine de toiles dont certains éléments

  14. Liquid-Liquid Extraction Processes 

    E-print Network

    Fair, J. R.; Humphrey, J. L.

    1983-01-01

    the two liquid phases, separation will result. This is the principle upon which separation by liquid-liquid extraction is based, and there are a number of important applications of this concept in industrial processes. This paper will review the basic...

  15. Fractal Liquids

    E-print Network

    Marco Heinen; Simon K. Schnyder; John F. Brady; Hartmut Löwen

    2015-05-05

    We introduce fractal liquids by generalizing classical liquids of integer dimensions $d = 1, 2, 3$ to a fractal dimension $d_f$. The particles composing the liquid are fractal objects and their configuration space is also fractal, with the same non-integer dimension. Realizations of our generic model system include microphase separated binary liquids in porous media, and highly branched liquid droplets confined to a fractal polymer backbone in a gel. Here we study the thermodynamics and pair correlations of fractal liquids by computer simulation and semi-analytical statistical mechanics. Our results are based on a model where fractal hard spheres move on a near-critical percolating lattice cluster. The predictions of the fractal Percus-Yevick liquid integral equation compare well with our simulation results.

  16. SURVEILLANCE ET CONTROLE DES ACTIVITES DES NAVIRES EN MER

    E-print Network

    Paris-Sud XI, Université de

    1 SURVEILLANCE ET CONTROLE DES ACTIVITES DES NAVIRES EN MER ScanMaris Michel MOREL (DCNS), Aldo administrations en mer. Toutefois, ils ne recueillent des informations que pour des zones maritimes ou des permanente, un recueil massif de données permettant de mieux gérer les situations en mer et les interventions

  17. 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 (Univ. of Tokyo (Japan)); Arakawa, Hironori (National Chemical Lab. for Industry, Ibaraki (Japan)); Isobe, Kiyoshi (Inst. for Molecular Science, Aichi (Japan))

    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.

  18. Triangle des vitesses Failles transformantes

    E-print Network

    Grigné, Cécile

    Triangle des vitesses ab Failles transformantes A B A B TD - UE Terre Profonde #12;Triangle des vitesses ab A B Dorsales A B TD - UE Terre Profonde #12;Triangle des vitesses ab B A B A Subduction TD - UE Terre Profonde #12;Triangle des vitesses B A A B C C TD - UE Terre Profonde #12;Triangle des vitesses B

  19. Liquid membranes

    SciTech Connect

    Araki, T. (Kyoto Inst. of Tech. (Japan)); Tsukube, H. (Okayama Univ. (Japan))

    1990-01-01

    This work describes newer applications of liquid membrane systems which contain molecular and/or ion recognizing carrier compounds and the related characteristic membrane materials. It focuses on the current knowledge about chemistry, biology and related technology of liquid membranes. It reviews the most recent advances in design and characteristics of synthetic liquid membrane transport. Up-to-date topics in the analytical and separation science, plus biomimetic membrane technology are discussed.

  20. CULTURE DES VIVRIERS. COMBINAISON DES SAVOIRS LOCAUX ET MODERNES. ANTHROPOLOGIE COMME CONSTRUCTION DES PONTS CULTURELS

    E-print Network

    Boyer, Edmond

    DES PONTS CULTURELS BAÏNILAGO L. ISDA 2010, Montpellier 28-30 Juin 2010 CULTURE DES VIVRIERS. COMBINAISON DES SAVOIRS LOCAUX ET MODERNES:ANTHROPOLOGIE COMME CONSTRUCTION DES PONTS CULTURELS LOUIS'anthropologie, construction des ponts culturels ABSTRACT : This paper tries to criticize the radical opposition established

  1. Expression des constantes de distorsion centrifuge des hexafluorures en fonction des frquences harmoniques.

    E-print Network

    Paris-Sud XI, Université de

    L-55 Expression des constantes de distorsion centrifuge des hexafluorures en fonction des de distorsion centrifuge des molécules XY6 en fonc- tion des fréquences harmoniques ; l for the centrifugal distortion constants as a function of harmonic frequencies ; application is made to SF6 and UF6. 4

  2. 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. (Brookhaven National Lab., Upton, NY (USA))

    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}.

  3. 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.

  4. Amputation des quatre membres

    PubMed Central

    Feruzi, Maruis Kitembo; Milindi, Cédrick Sangwa; Zabibu, Mireille Kakinga; Mulefu, Jules Panda; Katombe, Francois Tshilombo

    2014-01-01

    Les auteurs présentent les cas d'amputation des quatre membres réalisée chez trois patients différents. Ce sont des amputations réalisées pour chaque patient au cours d'une seule hospitalisation et en un seul temps opératoire. Deux patients pour gangrène sèche infectée et un pour amputation traumatique des quatre membres. L'amputation d'urgence a été pratiquée en premier temps suivie de remodelage des moignons d'amputation en second temps. L’évolution de tous les patients a été bonne. PMID:25469177

  5. Klinische Wertbestimmung des Convallatoxins

    Microsoft Academic Search

    Bruno Weicker

    1932-01-01

    Zusammenfassung Untersuchungen über die pharmakologische und klinische Auswertung des Convallatoxins, eines von Karrer aus der Convallaria majalis dargestellten kristallisierten Glykosids der Firma Hoffmann-La Roche erergeben:

  6. Étude des équilibres solide-liquide du système quaternaire réciproque H 2O?UO 2(NO 3) 2, H 2 O 2 ( HNO 3) 2 , UO 4. Partie 1. Méthodes et techniques d'étude

    Microsoft Academic Search

    J. J Counioux; S Gentil; R Tenu

    1995-01-01

    Hydrated uranium peroxide (UO4 · nH2O with n = 2, 4 or 92) can be obtained by the reaction between hydrogen peroxide and uranyl nitrate. The optimal conditions for obtaining these compounds in a nitric medium require knowledge of the solid-liquid equilibrium of the reciprocal quaternary system H2O?UO2(NO3)2, H2O2(HNO3)2, UO4. The spontaneous decomposition of hydrogen peroxide into water and oxygen

  7. 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.

  8. 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.

  9. 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

  10. Politique de gestion des documents administratifs et des archives

    E-print Network

    Politique de gestion des documents administratifs et des archives Préparation : Division de la gestion des documents administratifs et des archives Révision : Bureau du secrétaire général Entrée en vigueur : 15 février 2012 Approbation : (CA-2012-6) Cadre juridique : Loi sur les archives (L

  11. Des pionniers autoconstructeurs aux cooprateurs : histoire des Castors en Aquitaine

    E-print Network

    Boyer, Edmond

    Des pionniers autoconstructeurs aux coopérateurs : histoire des Castors en Aquitaine Julie ­ Histoire des Castors en Aquitaine - 2010 2 Préambule Ce travail est un manuscrit en cours de travail. Il Castors en Aquitaine, des pionniers autoconstructeurs aux coopérateurs (1948-1970) initialement traité

  12. MITTEILUNGSBLATT DES REKTORS

    E-print Network

    Gertz, Michael

    Landeshochschulgebühren- gesetzes (LHGebG) vom 1. Januar 2005 (GBl. S. 1, 56 ff.), zuletzt geändert durch Artikel 6 des Dritten Hochschulrechtsänderungsgesetz vom 1. April 2014 (GBl. S. 99, 167) in Verbindung mit § 19 Abs. 1 Nr. 10 Landeshochschulgesetz vom 1. Januar 2005 (GBl. S. 1), zuletzt geändert durch Artikel 1 des

  13. Echte Lipome des Meniscus

    Microsoft Academic Search

    G. Stedtfeld

    1955-01-01

    Es werden 2 Fälle beschrieben, bei denen ein echtes Lipom des Meniscus gefunden wurde. Nach kurzer Wiedergabe der Krankengeschichten und Operationsberichte werden Lokalisation, Form und histologischer Aufbau der Geschwülste in 5 Abbildungen gezeigt. In der abschließenden Epikrise wird auf die diagnostischen Schwierigkeiten hingewiesen und die Entfernung des ganzen Meniscus angeraten.

  14. Name des Akademischen Lehrkrankenhauses

    E-print Network

    Gollisch, Tim

    -5 99947 Bad Langensalza Name der / des PJ Beauftragten Kontaktaufnahme Frau Prof. Dr. Borg-von Zepelin Unterkunft In Absprache mit der Klinik Ansprechpartner: Frau Eva Ackermann Tel.: 03601- 41 1132 e Kontaktaufnahme Frau Dr. Christiane Först Sekretariat: Frau Rochner Tel.: 0441 / 9615-240 Treffpunkt am 1.Tag des

  15. Exploring Liquids

    NSDL National Science Digital Library

    2012-06-26

    Young learners investigate and observe the properties of three liquids -- water, vegetable oil, and corn syrup. They use their senses to collect data and ask and answer questions. This lesson for young learners introduces the scientific process.

  16. Eléments de comparaison internationale des patrimoines des ménages

    Microsoft Academic Search

    Dominique Strauss-Kahn

    1979-01-01

    [fre] A partir des bribes d'information existant sur les patrimoines de divers pays européens et des USA, une comparaison de la structure des patrimoines des inégalités de répartition et de leur évolution est tentée. Actifs financiers et actifs réels figurent de façon variable dans les patrimoines des différents pays. La Grande-Bretagne, avec une forte part d'actifs financiers, notamment de valeurs

  17. [Are liquid crystals living organisms?].

    PubMed

    Snelders, H A

    1997-01-01

    In 1888 the Austrian botanist F. Reinitzer made the observation that the solid compound cholesteryl-benzoate changes - when melting at 145.5 oC - into a cloudy liquid, that however, turns into a clear liquid at 178.5 oC and higher temperatures. The cloudy liquid seemed to be doubly refracting. Soon a number of these so-called 'liquid crystals' were discovered; in 1908 D. Vorländer, professor of organic chemistry at Halle, described more than 250 of these substances. It was O. Lehmann, professor of physics at Aachen (1885), Dresden (1888) and Karlsruhe (1889), who immediately after Reinitzer's observation began a systematic study of these liquid crystals. In The Netherlands the Amsterdam professor of physican chemistry H. W. Bakhuis Roozeboom was interested in liquid crystals, in particular because of their place in his phase system. F.M. Jaeger, at that time teaching chemistry in a secondary school in Zaandam (near Amsterdam) and working as an unpaid university lecturer at the Amsterdam university (by recommendation of Bakhuis Roozeboom), investigated liquid crystals (1906), as did a number of doctoral students (A.C. de Kock, 1903; A. Prins, 1907). At the university of Utrecht L.S. Ornstein, professor of physics, gave the study of liquid crystals a prominent place in his research programme. The discovery of liquid crystals, which seemed to be able to grow, move, divide, copulate, and so on, led to a discussion on the nature of these substances. Time and again Lehmann called them 'apparently living crystals', although without considering them as 'real living beings'. In his book Flüssige Kristalle und die Theorien des Lebens (1906), Lehmann proved to be an obvious adherent of the monistic views of the biologist E. Haeckel. Haeckel considered the existence of liquid crystals as proof of the unity between the inorganic and the organic world that he believed in so strongly. In his last book, Kristallseelen. Studien über das Anorganische Leben (1917), he considered liquid crystals a real form of life, as did F. Rinne, professor of mineralogy and petrography, as late as in the nineteen thirties. PMID:11625121

  18. INFLAMMATION DES NUAGES DE POUSSIERES PAR DES ETINCELLES ET DES SURFACES CHAUFFEES

    E-print Network

    Paris-Sud XI, Université de

    2001-74 INFLAMMATION DES NUAGES DE POUSSIERES PAR DES ETINCELLES ET DES SURFACES CHAUFFEES C. PROUST - M. BOUDALAA INERIS-BP 2- F60550 Veraeuil-en-Halatte Résumé. Les trois types de sources d'inflammation utilisé. Pour des délais d'inflammation relativement longs (1 à 2 mn), le paramètre caractéristique de l'inflammation

  19. Liquid marbles.

    PubMed

    Aussillous, P; Quéré, D

    2001-06-21

    The transport of a small amount of liquid on a solid is not a simple process, owing to the nature of the contact between the two phases. Setting a liquid droplet in motion requires non-negligible forces (because the contact-angle hysteresis generates a force opposing the motion), and often results in the deposition of liquid behind the drop. Different methods of levitation-electrostatic, electromagnetic, acoustic, or even simpler aerodynamic techniques-have been proposed to avoid this wetting problem, but all have proved to be rather cumbersome. Here we propose a simple alternative, which consists of encapsulating an aqueous liquid droplet with a hydrophobic powder. The resulting 'liquid marbles' are found to behave like a soft solid, and show dramatically reduced adhesion to a solid surface. As a result, motion can be generated using gravitational, electrical and magnetic fields. Moreover, because the viscous friction associated with motion is very small, we can achieve quick displacements of the droplets without any leaks. All of these features are of potential benefit in microfluidic applications, and also permit the study of a drop in a non-wetting situation-an issue of renewed interest following the recent achievement of super-hydrophobic substrates. PMID:11418851

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

    E-print Network

    Leclercq, Remi

    #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

  1. Le magazine Prsentation des

    E-print Network

    Le magazine Présentation des guides Abonnez-vous La lettre professionnelle Recevez la newsletter FINANCEMENT EUROPE ET MONDE FORMATION Innovation Online - L´actualité de l'économie de la croissance http://www.innovationonline.fr/articles-magazine

  2. Zur Pharmakologie des Cytisins

    Microsoft Academic Search

    J. Zachowski

    1938-01-01

    Zusammenfassung 1.Das goldregenalkaloid Cytisin bewirkt wie Nikotin Erregung der vegetativen Schaltganglien mit nachfolgender Lähmung. Die erregende Wirkung des Cytisins betrifft fast nur die sympathischen Schaltganglien.2.Vom Nikotin unterscheidet es sich wesentlich durch die bedeutend stärkere Erregung der sympathischen Schaltganglien und durch die stark abgeschwächte lähmende Wirkung.3.Die im Vergleich zu Nikotin vielfach stärkere adrenalinartige pressorische Wirkung des Cytisins beruht in erster Linie

  3. 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

  4. 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

  5. Layered Liquids

    NSDL National Science Digital Library

    John Eichinger

    2009-05-30

    This activity involves an exploration of density. Why does oil float on water? How does drain cleaner sink down into the clogged pipe right through standing water? These questions will be answered as students make a layered "parfait" of colored liquids ba

  6. PROPRITS MCANIQUES DES VERRES J. ZARZYCKI

    E-print Network

    Paris-Sud XI, Université de

    789 PROPRIÉTÉS MÉCANIQUES DES VERRES J. ZARZYCKI Université de Montpellier 2, Laboratoire des Verres du C. N. R. S., France Résumé. 2014 La résistance mécanique des verres usuels s'écarte très des propriétés mécaniques des verres. Après un brefrappel de la théorie des microfissures (Inglis

  7. Critical thickness of a hybrid aligned nematic liquid crystal cell G. Barbero (*) and R. Barberi

    E-print Network

    Paris-Sud XI, Université de

    609 Critical thickness of a hybrid aligned nematic liquid crystal cell G. Barbero (*) and R discuss the director deformation inside a hybrid aligned nematic (HAN) cell, assuming that the surface analysé la déformation des cristaux liquides nématiques dans une cellule avec alignement planaire sur une

  8. et discipline ou spcialit cole Nationale Suprieure des Mines d'Albi-Carmaux conjointement avec l'INP Toulouse

    E-print Network

    Paris-Sud XI, Université de

    conventionnels ont été sélectionnés : l'injection par transfert de résine (RTM : Resin Transfer Molding) et l'infusion de résine sous vide (LRI : Liquid Resin Infusion). Les constituants des composites sont d'une part composites : liquid molding and mechanical behavior Abstract : This research work is part

  9. 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.

  10. Convertisseur d'images a cristal liquide et photoconducteur

    Microsoft Academic Search

    M. Frappier; G. Assouline; M. Hareng; E. Leiba

    1971-01-01

    Un milieu nématique soumis à un champ électrique et traversé par un courant électrique devient fortement diffusant. La juxtaposition d'une couche photoconductive au nématique permet de moduler la diffusion du cristal liquide par des variations d'éclairement. On réalise ainsi un « relais de lumière » qui, par sa simplicité, remplace avantageusement les autres procédés de projection d'informations sur grand écran

  11. OSCILLATION D'UN JET LIQUIDE Par GUY LITTAYE.

    E-print Network

    Boyer, Edmond

    à l'extrémité d'un tube de verre court. Le liquide, l'eau en l'espèce, est amené au tube de verre par un tube de caoutchouc. Le tube de verre est fixé sur une lame d'acier qui effectue des observer exception- nellement un aspect semblable du jet alors que le tube de verre était soigneusement

  12. Optimisation du dimensionnement des alimentations des machines rluctance variable

    E-print Network

    Paris-Sud XI, Université de

    qui minimisent le dimensionnement du convertisseur tant en courant qu'en tension. Après un rappel des dimensionnement des convertisseurs prenant en compte les valeurs efficaces ou maximales des courant et tension adjoindre un convertisseur d'alimentation à fréquences élevées (jusqu'à quelques kHz). En général, il est à

  13. Qualit des composts et des digestats Fabienne MULLER

    E-print Network

    Boyer, Edmond

    Qualité des composts et des digestats Fabienne MULLER Direction consommation durable et déchets organiques se construit, avec aujourd'hui le développement important de la méthanisation. Les composts actuellement produits, peuvent l'être avec des digestats ou non. Les quantités de compost produit ne cessent d

  14. Facult des arts et des sciences Dpartement de psychologie

    E-print Network

    Parrott, Lael

    ) L'étudiant choisit les cours du profil Enfants/adolescents (Axe 1), ou du profil Adultes (Axe 2). Cours Axe 1 : Évaluation enfants - adolescents Crédits Inscription Annulation Trimestre Année PSY7236;Faculté des arts et des sciences Département de psychologie Secrétariat des études supérieures Cours Axe 2

  15. SURVEILLANCE ET CONTROLE DES ACTIVITES DES NAVIRES EN MER

    E-print Network

    Boyer, Edmond

    1 SURVEILLANCE ET CONTROLE DES ACTIVITES DES NAVIRES EN MER ScanMaris Michel MOREL (DCNS), Aldo) «Quiconque est maître sur la mer a un grand pouvoir sur la terre» Cardinal de Richelieu Il est donc Surveillance et de Sauvetage), sémaphores, moyens nautiques et aériens des administrations en mer. Toutefois

  16. Septembre 2012 Paludisme : des moustiques

    E-print Network

    pulvérisations intra domiciliaires d'autres insecticides, les carbamates. Ces derniers agissent différemment au aux pyré- thrinoïdes et pulvérisé des carbamates à l'intérieur des habitations, les scientifiques ont

  17. 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.

  18. Pump for Saturated Liquids

    NASA Technical Reports Server (NTRS)

    Elliott, D. G.

    1986-01-01

    Boiling liquids pumped by device based on proven components. Expanding saturated liquid in nozzle and diverting its phases along separate paths in liquid/vapor separator raises pressure of liquid. Liquid cooled in process. Pump makes it unnecessary to pressurize cryogenic liquids in order to pump them. Problems of introducing noncondensable pressurizing gas avoided.

  19. Déviance et contrôle des comportements

    Microsoft Academic Search

    Lionel Honoré

    2006-01-01

    (VF)Quel rôle joue le contrôle des comportements et que devient la place de la déviance lorsque les règles s’écartent et que l’autonomie, l’initiative, le progrès constant, deviennent des principes du fonctionnement de l’entreprise et de l’organisation du travail ? Pour tenter d’apporter des éléments de réponses à cette question, nous l’étudions sous l’angle des théories de la déviance. L’objectif est,

  20. 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

  1. Chiral liquids

    NASA Astrophysics Data System (ADS)

    Zakharov, V. I.

    2015-05-01

    We review briefly properties of chiral liquids, or liquids with massless fermionic constituents. We concentrate on three effects, namely, the low ratio of viscosity ? to entropy density s, chiral magnetic and vortical effects. We sketch standard derivations of these effects in the hydrodynamic approximation and then concentrate on possibile unifying approach which is based on consideration of the (anomalously) conserved axial current. The point is that the conservation of chirality is specific for the microscopic, field-theoretic description of massless fermions and their interactions. On the macroscopic side, the standard hydrodynamic equations are not consistent, generally speaking, with conservation of a helical macroscopic motion. Imposing extra constraints on the hydrodynamics might resolve this "clash-of-symmetries" paradox.

  2. NOTE TECHNIQUE RECHERCHE DES SALMONELLA

    E-print Network

    Paris-Sud XI, Université de

    NOTE TECHNIQUE RECHERCHE DES SALMONELLA PAR IMMUNOFLUORESCENCE M. CATSARAS J. ANANI Laboratoire Salmonella, 366 prélèvements, dans 125 boucheries, pour lesquels nous avons comparé les techniques d, dus à des coliformes. Ses avantages et ses inconvénients pour la recherche des Salmonella sont

  3. How S-DES Works

    Microsoft Academic Search

    Febiana Hanani; Indri Rahmayuni

    Data Encryption Standard (DES) is one of the most widely used symmetric key cryptography algorithm. Therefore, the susceptibility of DES to different kind of attacks has been a concern since the algorithm was first made public. The problem has escalated to the point that Electronic Frontier Foundation has now built a DES cracking machine, at a cost of less than

  4. Die pharmakologische Wirkung des Ephedrins

    Microsoft Academic Search

    H. Kreitmair

    1927-01-01

    Zusammenfassung 1.Die pharmakologische Wirkung des Ephedrins wurde zu analysieren versucht durch Studium der Beeinflussung des Blutdrucks, der Herzaktion und der Gefäße, des Effekts am Atemzentrum und an den Bronchien, der Wirkung auf die Pupillenweite, auf den Darm und den Uterus, auf die Sekretion verschiedener Drüsen und den Blutzuckerspiegel.2.Es wurden folgende Wirkungen gefunden: Der Blutdruck wird erhöht durch kleine Dosen, erniedrigt

  5. CIBLE DE TRITIUM LIQUIDE M. CHEMARIN, L. FEUVRAIS, M. GOUANRE, M. C. LEMAIRE et G. NICOLA,

    E-print Network

    Paris-Sud XI, Université de

    236. CIBLE DE TRITIUM LIQUIDE M. CHEMARIN, L. FEUVRAIS, M. GOUAN�RE, M. C. LEMAIRE et G. NICOLAÏ, Institut de Physique Nucléaire, Lyon. Résumé. - On présente une cible de tritium ou deutérium liquide de petite dimension : 0,4 cm3 de tritium liquide, soit une perte d'énergie de 1,4 MeV pour des deutons de 27

  6. Liquid air mixing system

    NASA Technical Reports Server (NTRS)

    Martin, Robert B. (Inventor)

    1997-01-01

    A device for mixing liquid nitrogen and liquid oxygen to form liquid air. The mixing device consists of a tube for transferring liquid oxygen positioned within a tube for transferring liquid nitrogen. Supply vessels for liquid oxygen and liquid nitrogen are equally pressurized and connected to the appropriate tubes. Liquid oxygen and nitrogen flow from the supply vessels through the respective tubes and are mixed to form liquid air upon exiting the outlets of the tube. The resulting liquid air is transferred to a holding vessel.

  7. TIC et commerce lectronique : laboratoires de la libralisation des changes et des volutions des rgles

    E-print Network

    Paris-Sud XI, Université de

    1 TIC et commerce électronique : laboratoires de la libéralisation des échanges et des évolutions/Département Sciences Economiques et Sociales Les échanges internationaux de produits TIC et le commerce électroniques à terme à l'abolition des droits de douane pour les produits de la filière TIC et les échanges

  8. Liquid Rainbow

    NSDL National Science Digital Library

    Mid-continent Research for Education and Learning (McREL)

    2004-01-01

    In this density activity, students determine the relative densities of five liquids and layer them atop one another in a straw. Directions for conducting the activity are included in addition to lists of the science process skills, complex reasoning strategies, and National Science Education Standards that relate to it. A brief explanation of the activity's science content and an assessment idea are also provided. This activity is part of a set called Whelmers that were designed to inspire students to think about science concepts.

  9. 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.

  10. Gestion processuelle des rsultats : Une tude pr-et post-IFRS des dpenses de R&D des

    E-print Network

    1 « Gestion processuelle des résultats » : Une étude pré- et post-IFRS des dépenses de R&D des'adoption des normes IFRS n'a pas neutralisé la capitalisation discrétionnaire des dépenses de R&D, mais que, à. Then the paper focuses on how accounting standards used (PCG/IFRS) alter earnings management based on R

  11. 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

  12. BULLITIONS NUIT DES SCIENCES

    E-print Network

    Gutkin, Boris

    partenariat avec TV5MONDE, Le Monde.fr, France culture Plus et l'Institut français, l'ENS a aussi souhaité de l'événement et des débats animés par Mohamed Kaci (TV5MONDE). Plusieurs thèmes seront abordés : la partager cette nuit avec le plus grand nombre, grâce à un plateau web-tv diffusé en direct dans le monde

  13. COMPORTEMENT SCURITAIRE DES

    E-print Network

    Paris-Sud XI, Université de

    , Robert Latour 1 Résumé Abstract Des données fournies par 109 utilisateurs de systèmes informatiques ont.., CA et Robert Latour L. SC. Com., C.S.E. stat., professeurs agrégés (avec la collaboration de Jacques-5633 Courrier électronique : andre.peres@hec.ca et robert.latour@hec.ca halshs-00587496,version1-20Apr2011

  14. Bilan des turbulences

    Microsoft Academic Search

    Françoise Milewski; Hervé Péléraux; Olivier Passet; Christine Rifflart; Jean-Marc Daniel

    1994-01-01

    [eng] Turbulences' check-up Département des diagnostics Western economies began their recovery one year ago, but it is still difficult to foresee jobs and capacities creations on the near term. National situations exhibit quite varied imprints of indebtedness and disindebtedness waves brought about by the deregulations and monetary policies. Continental Europe, Germany excepted, has achieved the curbing of corporate failures, but

  15. 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.

  16. ECOLE DOCTORALE Savoirs scientifiques : pistmologie, histoire des

    E-print Network

    Paris-Sud XI, Université de

    1 ECOLE DOCTORALE Savoirs scientifiques : épistémologie, histoire des sciences, didactique des-DIDEROT, PARIS 7 & DOCTEUR DE L'UNIVERSITE VIRTUELLE DE TUNIS Spécialité : Didactique des mathématiques Présentée'enseignement sur les possibilités d'apprentissage des étudiants Cas des notions ensemblistes fonctionnelles dans la

  17. EVALUATION DES INTERFACES UTILISATEUR : TAXONOMIE ET RECOMMANDATIONS

    E-print Network

    Nigay, Laurence

    'Assurance Qualité se pratique à façon, en fonction des ressources et des objectifs. A chaque cas, sa méthode. Nous Méthodes candidates Résultats souhaités Figure 1 : Choix d'une méthode d'évaluation en fonction des coûts (appel à des experts pratiquant par exemple la technique structurée des ``cognitive walkthrough'' [LEWIS

  18. fevrier 2012 Journes Francophones des Langages Applicatifs JFLA12 Separation des couleurs dans un -calcul bichrome

    E-print Network

    Paris-Sud XI, Université de

    AlligatorEggs3 cherche `a expliquer le -calcul `a des enfants. Pour cela il utilise la couleur pour relier des alligators affam´es et des oeufs afin de constituer des familles. La couleur sert `a expliciter les liaisons des variables dans les termes, des oeufs naissent de nouveaux alligators ou familles lors

  19. Guidance Document Cryogenic Liquids

    E-print Network

    are liquid nitrogen, liquid argon and liquid helium. The different cryogens become liquids under different oxygen could produce an oxygen-rich atmosphere which could accelerate combustion of other materials cryogenic liquid. But materials such as carbon steel, plastic and rubber become brittle and may fracture

  20. 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

  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. 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, ...

  4. 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 ...

  5. Liquid-liquid-solid transition in viscoelastic liquids

    PubMed Central

    Zubelewicz, Aleksander

    2013-01-01

    Liquid-liquid-solid transitions (LLST) are known to occur in confined liquids, exist in supercooled liquids and emerge in liquids driven from equilibrium. Molecular dynamics (MD) simulations claim many successes in forecasting the phenomena. The transitions are also studied in the framework of thermodynamics based methods and minimalistic models. In here, the proposed approach is derived in the framework of continuum and includes spatial and temporal dynamic heterogeneities; the approach is meant to capture the material behavior at small scales. We conjecture that the liquid-like and solid-like behaviors are dissimilar enough for the two to be governed by different constitutive relations. In this way, we gain additional degree of freedom, which is found essential when predicting the transitional phenomena. As a result, we derive the LLST criteria for liquids in equilibrium, during steady flow and at transient conditions. Lastly, we forecast short-lived LLSTs in human blood during cardiac cycle. PMID:23429528

  6. CARACTRES CYTOLOGIQUES DES CELLULES GONADOTROPES, THYROTROPES, CORTICOTROPES,

    E-print Network

    Boyer, Edmond

    , LTH, ACTH) et les distinguant du groupe des cellules à contenu glycoprotidique (FSH, LH, TSH). b) Bleu distribution très hétérogène des cellules TSH, à l'abondance des cellules ACTH, ces trois dernières catégories

  7. PHNOMNES DE TRANSPORT ATOMIQUE DANS LES ALLIAGES LIQUIDES INDIUM-PLOMB

    E-print Network

    Boyer, Edmond

    PAGE L-89 PHÉNOMÈNES DE TRANSPORT ATOMIQUE DANS LES ALLIAGES LIQUIDES INDIUM-PLOMB J. F. RIALLAND le système indium- plomb à l'aide d'un modèle de sphères dures. A partir des données expérimentales, on obtient des diamètres de c0153ur dur de 3,04 Å pour l'indium et 3,40 Å pour le plomb. Les distances entre

  8. Les mtiers des langues trangres

    E-print Network

    Jeanjean, Louis

    individuel, en groupe, en face à face ou à distance, par téléphone ou en ligne. Il doit être en mesure de s'adapter à des publics sans cesse renouvelé, il faut alors faire preuve de capacités de communication et d'adaptation enseigner les termes de la vie quotidienne à des migrants ou un français plus technique s'il s'adresse à des

  9. V-Durabilit des cramiques et des verres Ce chapitre se propose de traiter de la tenue long terme des cramiques et des verres.

    E-print Network

    V- Durabilité des céramiques et des verres Ce chapitre se propose de traiter de la tenue à long terme des céramiques et des verres. A partir d'exemples présentés dans une première partie, une démarche dans une démarche de conception fiabiliste de composants contenant des verres ou/et des céramiques. V.1

  10. Deep eutectic solvents formed between choline chloride and carboxylic acids: versatile alternatives to ionic liquids.

    PubMed

    Abbott, Andrew P; Boothby, David; Capper, Glen; Davies, David L; Rasheed, Raymond K

    2004-07-28

    Deep Eutectic Solvents (DES) can be formed between a variety of quaternary ammonium salts and carboxylic acids. The physical properties are significantly affected by the structure of the carboxylic acid but the phase behavior of the mixtures can be simply modeled by taking account of the mole fraction of carboxylic acid in the mixture. The physical properties such as viscosity, conductivity, and surface tension of these DES are similar to ambient temperature ionic liquids and insight into the cause of these properties is gained using hole-theory. It is shown that the conductivity and viscosity of these liquids is controlled by ion mobility and the availability of voids of suitable dimensions, and this is consistent with the fluidity of other ionic liquids and molten salts. The DES are also shown to be good solvents for metal oxides, which could have potential application for metal extraction. PMID:15264850

  11. Chemotherapie des metastasierten Nierenzellkarzinoms

    Microsoft Academic Search

    Hans-Joachim Beck; C. Huber

    1998-01-01

    Die Lebenserwartung des Patienten mit metastasiertem Nierenzellkarzinom (NZK) ist kurz, so liegt die 5-Jahresüberlebenszeit\\u000a im Stadium IV mit Fernmetastasen unter 10% [5]. Dennoch existiert eine kleine Gruppe von Patienten, die durch günstigeren\\u000a Spontanverlauf und lange Überlebenszeiten charakterisiert ist. Desweiteren kommt es beim NZK zu immer wieder beschriebenen\\u000a Spontanremissionen [12], die jedoch in den wenigen einschlägigen Studien mehrheitlich unter 1% liegen.  

  12. Seltene Tumoren des Integuments

    Microsoft Academic Search

    U. Hofmann; A. Stein; H. Helmbach; A. Philipp; D. Schadendorf

    1999-01-01

    An der Haut manifestieren sich die hufigsten Malignome des Menschen, die epidermalen Plattenepithel- und Basalzellkarzinome,\\u000a sowie auch maligne Melanome mit steigender Inzidenz. Darber hinausgehend sind eine betrchtliche Zahl weiterer, verschiedenartigster,\\u000a jedoch vergleichsweise seltener Tumore am Integument zu beobachten. Das vor allem histologisch bunte Bild resultiert aus Gewebsanteilen\\u000a meso- und ektodermalen Ursprungs, welche in ausgesprochener Differenzierungsvielfalt die Haut und Unterhaut konstituieren.

  13. Strukturanalyse des Hämoglobin Köln

    Microsoft Academic Search

    R. W. Carrell; H. Lehmann; W. Pribilla

    1967-01-01

    Zusammenfassung Obwohl das Hb Köln zuerst in Deutschland bei einer Familie aus Köln gefunden wurde, gelang die Aufklärung der molekularen Strukturanomalie erstmalig bei einer aus Glasgow stammenden Familie, die einige deutsche Vorfahren hat. Es konnte mit verschiedenen Methoden gezeigt werden, daß Hb Köln folgende Struktur hat: a2ß2 98 Val?Met. Die in dieser Arbeit dargestellten Untersuchungen zeigen, daß die Strukturanomalie des

  14. J.-T. BOTTOMI,EY. -On experiments with vacuum gold-leaf electroscopes on the mechanical temperature effects in rarefied gases (Sur des expriences avec

    E-print Network

    Boyer, Edmond

    (Frottement interne des liquides visqueux et sa variation avec la pression). - P. 287-310. Stokes a calculé la seulement du frotte- ment interne. Si R désigne la résistance ; k, le coefficient de frottement interne du:019070060073401 #12;735 Si le frottement extérieur, c'est-à-dire de la sphère sur le liquide, est assez grand pour

  15. Liquid annulus

    NASA Technical Reports Server (NTRS)

    Ludewig, Hans

    1991-01-01

    It is shown that the specific impulse varies with the square root of the temperature and inversely with the square root of the molecular weight of the propellant. Typical values for specific impulse corresponding to various rocket concepts are shown. The Liquid Annulus core concept consists of a fuel element which will be arranged in a moderator block. The advantages as seen for the system are: high specific impulse; structural material will all run at low temperature; and lower fission product inventory because of evaporation. It is felt that this concept is worth at least a first look because of the promise of very high specific impulse. Because of the low thrust, one would probably need a cluster of engines. This is not necessarily bad because there would be some redundancy, but because of the low thrust one might have to refuel while running. Depending on the fuel vaporization, material can be included in the uranium that is injected as one is running along.

  16. Minimizing liquid contaminants in natural gas liquids

    SciTech Connect

    Brown, R.L. [Pall Industrial Process Filtration, East Hills, NY (United States); Wines, T.H. [Pall Scientific and Laboratory Services, Port Washington, NY (United States); Williamson, K.M. [Pall Process Equipment Development, Cortland, NY (United States)

    1996-12-31

    In processing natural gas liquids, significant contamination occurs with liquid dispersions and emulsions. Natural gas liquids (NGL) and liquid petroleum gas (LPG) streams are treated with caustic to remove residual organic sulfur compounds such as mercaptans and with amines to remove hydrogen sulfide. In both cases a liquid/liquid contactor is used. Significant amounts of the caustic or amine can be carried over into the product stream in process units that are running at rates above design capacity, are treating high sulfur feed stocks, or have other operational problems. The carried over liquid results in off-spec products, excessive loses of caustic or amine, and can cause operating problems in downstream processes. In addition, water is a significant contaminant which can cause LPG and natural gasoline to be off-specification. This paper discusses a new technique for separating very stable liquid dispersions of caustic, amine, or water from natural gas liquids using liquid/liquid cartridge coalescers constructed with specially formulated polymer and fluoropolymer medium with enhanced surface properties. In addition, factors influencing the coalescer mechanism will be discussed including interfacial tension, concentration of surface active compounds, steric repulsion, and electrostatic charge affects. Results from field tests, operating data from commercial installations, and economic benefits will also be presented.

  17. Le temps des unes et le temps des autres

    E-print Network

    Paris-Sud XI, Université de

    Le temps des unes et le temps des autres ans une journée tout le monde dispose de vingt-quatre heures. De quelle manière le temps est-il compté, quantifié et analysé selon les institutions ? Les temps. Dans les couples, hommes et femmes se ressemblent dans leur usage du temps sauf dans deux

  18. Facult des arts et des sciences Dpartement de sciences biologiques

    E-print Network

    Parrott, Lael

    i Faculté des arts et des sciences Département de sciences biologiques Plan de cours Politique sur étudiants de déposer leur copie d'examen et de libérer la salle. Ex : examen d'une durée de 1h45 ou de 2h45 2014 2h45 B-442 Les examens comportent deux parties: une série de 30 questions objectives et 2

  19. Facult des arts et des sciences Dpartement de sciences biologiques

    E-print Network

    Parrott, Lael

    i Faculté des arts et des sciences Département de sciences biologiques Plan de cours Politique sur étudiants de déposer leur copie d'examen et de libérer la salle. Ex : examen d'une durée de 1h45 ou de 2h45 examens comportent deux parties: une série de 30 questions objectives et 2-3 questions de synthèse ou d

  20. Rles indirects des microtubules dans la morphogense nuclaire des spermatides

    E-print Network

    Paris-Sud XI, Université de

    Rôles indirects des microtubules dans la morphogenèse nucléaire des spermatides J.-L. COURTENS. Summary. The indirect roles of microtubules in the nuclear morphogenesis of spermatids. The depolymerization of the microtubules of the spermatid manchette was effective for 4 to 5 h in rat, starting 30 min

  1. Plan de cours Facult des arts et des sciences

    E-print Network

    Parrott, Lael

    'analyse phylogénétique. Les 3 domaines du vivant: Archées, Eubactéries et Eucaryotes. Origine évolutive des Eucaryotes leurs niches écologiques. Éléments de contenu : Chapitre 6 - Origine évolutive des Végétaux. Végétaux et al. 2005 et de Campbell et al. 2012) #12;CALENDRIER Date Local Pavillon Contenu Mer. 8 mai 1409 A

  2. Exploration des Ondelettes en Prtraitement des Documents Anciens Anis Kricha

    E-print Network

    Paris-Sud XI, Université de

    Exploration des Ondelettes en Prétraitement des Documents Anciens Anis Kricha 1 ­ Amina Ghardallou de numérisation posent un axe de recherche très récent particulièrement pour les documents anciens présente une étape incontournable pour la restauration et le nettoyage d'un document. Elle permet d

  3. FACULTE DES ARTS ET DES SCIENCES DEPARTEMENT DE PHYSIQUE

    E-print Network

    Parrott, Lael

    FACULT´E DES ARTS ET DES SCIENCES D´EPARTEMENT DE PHYSIQUE AUTOMNE 2013 PLAN DE COURS Sigle du cours: PHY 1234 Titre du cours: Introduction `a la physique num´erique Nombre de cr´edits: 3 Professeur est offert principalement aux ´etudiant(e)s inscrit(e)s au premier cycle en physique et au programme

  4. A novel deep eutectic solvent-based ionic liquid used as electrolyte for dye-sensitized solar cells

    Microsoft Academic Search

    Huei-Ru Jhong; David Shan-Hill Wong; Chi-Chao Wan; Yung-Yun Wang; Tzu-Chien Wei

    2009-01-01

    We utilize a quaternary ammonium salt-derivative ionic liquid called G.CI which is a eutectic mixture of glycerol and choline iodide as electrolyte for dye-sensitized solar cells. Such eutectic compound belongs to a new series of ionic liquid called deep eutectic solvents (DES), which possess many outstanding features compared to the traditional imidazolium-based ionic liquids including cheap raw materials, simple preparation

  5. Bulk Viscosity of Liquids

    Microsoft Academic Search

    Nishio Hirai; Henry Eyring

    1958-01-01

    The mechanisms for bulk viscosity are different between associated and nonassociated liquids. Here, a new mechanism for bulk viscosity is proposed from the standpoint of the hole theory of liquids and the rate process theory. This mechanism can explain the temperature and pressure dependencies of acoustic absorption for associated liquids and very viscous nonassociated liquids.

  6. Liquidity and capital structure

    Microsoft Academic Search

    Marc L. Lipson; Sandra Mortal

    2009-01-01

    We examine the relation between equity market liquidity and capital structure. We find that firms with more liquid equity have lower leverage and prefer equity financing when raising capital. For example, after sorting firms into size quintiles and then into liquidity quintiles, the average debt-to-asset ratio of the most liquid quintiles is about 38% while the average for the least

  7. 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.

  8. Traveling Through Different Liquids

    NSDL National Science Digital Library

    2012-06-26

    Learners observe and record what happens when they manipulate bottles containing a liquid (water or corn syrup) and one or more objects (screw, nail, paper clip). They should observe differences in how quickly the objects fall in the different liquids. This lesson builds on what learners have studied in previous lessons, Exploring Liquids and Exploring How Liquids Behave.

  9. Rekonstruktion des Gesichts bei Verbrennungen

    Microsoft Academic Search

    Michael Steen

    2003-01-01

    Zusammenfassung Die Rekonstruktion des Gesichts bei Schwerbrandverletzten ist ein komplexer Bereich, bei dem schon die primäre Versorgung und Transplantationstechnik wesentlichen Einfluss auf das Endergebnis haben. Neben funktionellen Rekonstruktionen bei Narbenkontrakturen, Ektropion und inkomplettem Lidschluss, narbiger Begrenzung der Mundöffnung und Verlegungen des Naseneingangs finden heute auch Techniken Anwendung, welche vorrangig aus der ästhetischen Chirurgie bekannt sind. Beispiele dafür sind Haartransplantationen, Glättung

  10. Ageismus – Sprachliche Diskriminierung des Alters

    Microsoft Academic Search

    Undine Kramer

    Daniel Sanders, einer der bedeutendsten Lexikografen des 19. Jahrhunderts, wertete für sein Wörterbuch Quellen seit der Lutherzeit aus und\\u000a vermerkt im Wörterbuchartikel zu alt eine „bald lobende, bald tadelnde“ Bedeutung des Adjektivs. Sein Zeit- und Berufsgenosse Jacob Grimm benennt in seiner Rede über das Alter die zeitgenössischen Synonyme zu alt und Alter: „aus einheimischen schriftstellern liesze sich eine lange reihe

  11. HABILITATION `A DIRIGER DES RECHERCHES

    E-print Network

    Paris-Sud XI, Université de

    HABILITATION `A DIRIGER DES RECHERCHES PR´ESENT´EE `A L'UNIVERSIT´E CLAUDE BERNARD LYON I INSTITUT dilogarithme de Rogers . . . . . . . . . . . . . . . 19 2.4 Carquois et cat´egories d cambriens et ´equivalences d´eriv´ees . . . . . . . . . . . . 23 2.7 Cat´egorification des op

  12. La pertinence informationnelle des chiffres comptables aprs l'adoption des Mise en vidence du rle des facteurs institutionnels

    E-print Network

    Paris-Sud XI, Université de

    1 La pertinence informationnelle des chiffres comptables après l'adoption des IFRS Mise en évidence informationnelle additionnelle des chiffres comptables due à l'adoption des IFRS. Les tests empiriques ont porté financière (Dyck et Zingales 2007) et les différences entre les normes locales et les IFRS (Bae et al. 2008

  13. POSTES DE GRAVURE HUMIDE MANUELS Ce sont des postes scuriss qui permettent le traitement manuel des plaquettes dans des rcipients

    E-print Network

    Ingrand, François

    POSTES DE GRAVURE HUMIDE MANUELS Ce sont des postes sécurisés qui permettent le traitement manuel des plaquettes dans des récipients contenant le réactif de gravure humide CARACTERISTIQUES PRINCIPALES conduire une gravure humide (attaque chimique) du matériau concerné dans des récipients adaptés posés sur

  14. Les marchs des investisseurs institutionnels sont-ils efficients : cas des fonds de pension et des unit trusts britanniques

    E-print Network

    Paris-Sud XI, Université de

    Les marchés des investisseurs institutionnels sont-ils efficients : cas des fonds de pension et des, nous proposons d'étudier la persistance de la performance de deux échantillons de fonds (de pension et long terme, et en investissant sur le marché des actions, les fonds de pension ne semblent pas avoir

  15. Exploring How Liquids Behave

    NSDL National Science Digital Library

    Sharon Janulaw

    2010-01-01

    Learners apply their knowledge from a previous study to identify different liquids--water, corn syrup, and vegetable oil. They also investigate combinations of liquids, two at a time, to see how they interact. This is meant as a follow-up lesson to the related activity, Exploring Liquids. As an extension, learners can continue their study of these liquids in the lesson, Traveling Through Different Liquids.

  16. PHI 1901 : Pense rationnelle et argumentation Dpartement de philosophie, Facult des arts et des sciences

    E-print Network

    Parrott, Lael

    PHI 1901 : Pensée rationnelle et argumentation Département de philosophie, Faculté des arts et des rationalité et de l'importance de l'argumentation. Analyse du concept, de la définition et de la proposition, acceptabilité des prémisses, nécessité et suffisance. Étude des sophismes et des erreurs de raisonnements

  17. Evaluation des proprits thermiques de surface de la neige par assimilation des

    E-print Network

    Ribes, Aurélien

    simulations Crocus/forçage ERA-interim, les réanalyses ERA-interim et les données MODIS. #12;Plan I. Cycles, des simulations Crocus et des réanalyses ERA-interim IV. Conclusion et travaux envisagés #12;I. Cycles partir des données MODIS, des simulations Crocus et des réanalyses ERA-iterim #12;Cartes mensuelles de

  18. Gestion des terminologies riches : l'exemple des et Mathieu MANGEOT

    E-print Network

    Paris-Sud XI, Université de

    Gestion des terminologies riches : l'exemple des acronymes Ying ZHANG 1 et Mathieu MANGEOT 1 (1 ______________________________________________________________________________________________________________ La gestion des terminologies pose encore des problèmes, en particulier pour des constructions____________________________________________________________________________________________________________ Complex terminologies management ­ the case of acronyms Terminology management is still problematic

  19. Des Moines Water Works

    NSDL National Science Digital Library

    2001-01-01

    Users can access information about educational programs and materials for teachers and students, including tours, traveling exhibits and presentations by the staff of the Des Moines Water Works. "Water Trunks", which contain water-related literature, books, science experiments, videos, games, CD-ROMs, hands-on activities, picture cards, career information, and a teacher resource book, are available to order. There are also links to other water websites, a teachers' newsletter and pollution prevention tips for classroom use and for the general public.

  20. Formation et intgration Mise jour des dossiers

    E-print Network

    Spino, Claude

    Formation et intégration Mise à jour des dossiers du personnel Intégration des nouveaux employés les moyennes et grandes entreprises, ainsi que dans les domaines publics et de la consultation privée affaires permet aux étudiants d'acquérir des connaissances et des qualités propres au domaine de la gestion

  1. Gntique formelle des pigmentations humaines variations continues

    E-print Network

    Boyer, Edmond

    Génétique formelle des pigmentations humaines à variations continues : beaucoup d'hypothèses, peu et de mesures sont actuellement disponibles concer- nant la biochimie des pigments humains, leur génétique physiologique, les répartitions mondiales des pigmentations de la peau et des cheveux. La

  2. ACTION DES ANTIBIOTIQUES SUR PORCELETS ALLAITS

    E-print Network

    Boyer, Edmond

    VII. - ACTION DES ANTIBIOTIQUES SUR PORCELETS ALLAITÉS E. SALMON LEGAGNEUR M. MICHEL Station de. - Technique de distribution. C. - Animaux. D. - Dosage des antibiotiques. E. - Etude des flores intestinales : a) mortalité ; b) diarrhées ; c) régularité. D. - Étude des flores intestinales : a) Examen

  3. Absorptionsspektrum des Sehpurpurs und des Sehgelb. „Nachbleichung des Sehgelb im Dunkeln“

    Microsoft Academic Search

    Yuji Hosoya

    1934-01-01

    Zusammenfassung Eine photoelektrische Versuchsanordnung, die aus einer Selen-Sperrschichtphotozelle, einemMollschen Spiegelgalvanometer und einem Monochromator besteht, ist sehr geeignet das Absorptionsspektrum der photosensiblen Substanz der Netzhaut ohne die Gefahr der Bleichung während der Messung zu bestimmen. Mit diesen Meßgeräten wurde die spektrale Absorption des mit früheren, sowie neuerlich von mir benutzten Extraktionsmitteln hergestellten Sehpurpurs und des Sehgelb genauer und viel schneller als

  4. Integrated continuous microfluidic liquid-liquid extraction.

    PubMed

    Kralj, Jason G; Sahoo, Hemantkumar R; Jensen, Klavs F

    2007-02-01

    We describe continuous flow liquid-liquid phase separation in microfluidic devices based on capillary forces and selective wetting surfaces. Effective liquid-liquid phase separation is achieved by using a thin porous fluoropolymer membrane that selectively wets non-aqueous solvents, has average pore sizes in the 0.1-1 microm range, and has a high pore density for high separation throughput. Pressure drops throughout the microfluidic network are modelled and operating regimes for the membrane phase separator are determined based on hydrodynamic pressure drops and capillary forces. A microfluidic extraction device integrating mixing and phase separation is realized by using silicon micromachining. Modeling of the phase separator establishes the operating limits. The device is capable of completely separating several organic-aqueous and fluorous-aqueous liquid-liquid systems, even with high fractions of partially miscible compounds. In each case, extraction is equivalent to one equilibrium extraction stage. PMID:17268629

  5. DOMAINE DE TEMPRATURE DES PHNOMNES PRTRANSITIONNELS DANS LA PHASE ISOTROPE DES CRISTAUX LIQUIDES NMATIQUES

    E-print Network

    Paris-Sud XI, Université de

    -Mouton. Pour un materiau donne, on pourrait s'attendre a trouver, dans les deux cas, la meme difference Tl - Tc'en est pas de meme de ceux qui ont une -constante de Kerr negative comme MBBA, EBBA, PAA ; leur.1s) est la meme que celle qui a deja e

  6. 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 ?

  7. Amlioration des plantes Evolution des caractristiques de la graine

    E-print Network

    Paris-Sud XI, Université de

    'évolution de l'humidité du capitule et des graines de 25 variétés de tournesol (Helianthus annuus L.), de la of 25 sunflower (Helianthus annuus L.) varieties were followed from flowering to maturity, the oil

  8. Structure des disques d'accretion autour des etoiles jeunes

    E-print Network

    `eme solaire et de la terre 98% du moment - 0.2% de la masse formation des exoplan`etes And = ´Etudier l`eles de disque stationnaires Couplage hydrostatique-rayonnement, sans B. multi- gris 2 couches 1 couche

  9. Introduction to DES Overview of the DES Algorithm

    E-print Network

    under influence of the National Security Agency (NSA), the design criteria for DES have not been of Standards and Technology (NIST) · Most popular block cipher for most of the last 30 years. · By far best

  10. Ecophysiologie Vitesse d'mission des feuilles des brins matres

    E-print Network

    Paris-Sud XI, Université de

    conditionnement initial des plantules. Hordeum vulgare L = orge / phyllochrone / altitude / type de tallage these fators seem to act through an initial conditioning of the seedlings. Hordeum vulgare L / leaf emergence

  11. Phosphorus Recovery by Liquid–Liquid Extraction

    Microsoft Academic Search

    Jia-Qian Jiang; Onesmus Mwabonje

    2009-01-01

    It is acknowledged that phosphorus removal is more crucial in comparison with nitrogen removal for preventing algae glooming and eutrophication. Chemical and biological methods are common methods for the P removal. Excessive sludge production and difficulties of recovering phosphorus are concerns in terms of sustainable waste management. A liquid-liquid extraction (LLE) process is thus considered for the study aiming at

  12. Factorisons la gestion des vnements des applications interactives !

    E-print Network

    , des périphériques d'entrée/sortie autre que le clavier ou la souris. Afin de pouvoir implémenter et plusieurs composants: un premier pour les éléments classiques d'interface graphique (e.g. Motif), un deuxième pour les éléments plus spécifiques (e.g. OpenGL), un troisième pour la communication avec des

  13. 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.

  14. Thermal conductivity of liquids

    Microsoft Academic Search

    D. S. Viswanath

    1967-01-01

    The Bridgman equation for thermal conductivity of liquids is examined and a relation between sonic velocity and latent heat of vaporization is given. A correlation based on the hole theory of liquids is presented. This correlation predicts thermal conductivity in the temperature range of -20° to +80°C for 16 liquids, and at 20°C for 50 liquids with an average absolute

  15. Fiche technique Dtail des panneaux

    E-print Network

    - Biodiversité des cultures Panneau 4 - Paysage à Madagascar Panneau 5 - Labour d'un champ au Maroc Panneau 6 9 - Récolte d'un essaim d'abeilles au Maroc Panneau 10 - L'innovation en marche Panneau 11

  16. 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

  17. Die fermentative Spaltung des Acetylcholins

    Microsoft Academic Search

    R. Ammon

    1934-01-01

    Zusammenfassung Es wird eine neue Methode zum Nachweis des Fermentes, das Acetylcholin in Cholin und Essigsäure hydrolysiert, die Cholinesterase, beschrieben. Das Verfahren ist nach derWarburgschen Methode aufgebaut.

  18. PERFORMANCE DES ORGANISATIONS TRANSVERSALES HOSPITALIERES

    E-print Network

    Boyer, Edmond

    organizations, the Mobile Geriatrics Teams (MGTs). The findings draw on action research involving the 14 MGTs, Intangible Capital, Mobile Geriatrics Teams. Au cours des années 2000, le législateur a affirmé sa volonté d

  19. Thorie des ensembles 1. Motivation

    E-print Network

    Dolecki, Szymon

    , comme Georg Cantor (1845-1918), Giuseppe Peano (1858-1932), Bertrand Russell (1872-1970) et autres. Nous de la démonstration (2). Figure I.1. Georg Cantor, Giuseppe Peano et Bertrand Russell La plupart des

  20. 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.

  1. Vitrification and levitation of a liquid droplet on liquid nitrogen

    E-print Network

    Demirci, Utkan

    Vitrification and levitation of a liquid droplet on liquid nitrogen Young S. Songa , Douglas Adlera the liquid, when the liquid droplet comes into direct contact with liquid nitrogen. This is distinct from.e., vitrification) and the levitation of droplets on liquid nitrogen (i.e., Leidenfrost phenomenon) take place

  2. JUS 13331 (*,) THESE DE DOCTORATDEL 'ECOLENATIONALE DES PONTS ET CHAUSSEES

    E-print Network

    Paris-Sud XI, Université de

    JUS 13331 (*,) THESE DE DOCTORATDEL 'ECOLENATIONALE DES PONTS ET CHAUSSEES Spécialité Central des Ponts et Chaussées. Je remercie Monsieur Jean-François COSTE, Directeur du Laboratoire Central des Ponts et Chaussées, Monsieur Alain BONNET, Directeur des Actions Scientifiques et Techniques

  3. DTERMINATION DE LA TENEUR EN CIRE MICROCRISTALLINE DES MLANGES

    E-print Network

    Paris-Sud XI, Université de

    obtenus au cours des différentes opérations de raffinage des huiles lu- brifiantes de pétrole. Des microcristallines étant obtenues en grande partie au cours du raffinage des huiles, un contenu huileux subsiste avec

  4. Beiträge zur Geochemie des Kupfers

    Microsoft Academic Search

    K. H. Wedepohl

    1962-01-01

    Zusammenfassung  Das Cu kommt in häufigen Eruptivgesteinen nicht wie das Pb und Zn großenteils im Gitter der mineralischen Hauptbestandteile, sondern als Kupferkies vor (Proportionalität zwischen Cu- und S-Werten). Basaltische Gesteine haben wesentlich höhere Kupfergehalte (Mittel: 88 ppm = g\\/t Cu) als granitische (Mittel: 8 ppm Cu). Das Verhalten des Cu bei der Verwitterung und hydrothermalen Gesteinszersetzung und die Begrenzung des Transports

  5. Frustration in bilayers and topologies of liquid crystals of amphiphilic molecules

    E-print Network

    Paris-Sud XI, Université de

    683 Frustration in bilayers and topologies of liquid crystals of amphiphilic molecules J. F. Sadoc dicembre 1985) Résumé. - Les molécules amphiphiles construisent des films fluides symétriques, bicouches. - Amphiphilic molecules are well-known for their ability to build symmetric fluid films, or bilayers, most often

  6. Modlisation didactique et informatique des connaissances des lves en algbre Marie-Caroline Croset MMOIRE DE MASTER 2 RECHERCHE

    E-print Network

    Boyer, Edmond

    Modélisation didactique et informatique des connaissances des élèves en algèbre Marie-Caroline Croset MÉMOIRE DE MASTER 2 RECHERCHE ENVIRONNEMENTS INFORMATIQUES D'APPRENTISSAGE HUMAIN ET DIDACTIQUE UNIVERSITE JOSEPH FOURIER Modélisation didactique et informatique des connaissances des élèves en algèbre

  7. Radiation monitor for liquids

    DOEpatents

    Koster, James E. (Los Alamos, NM); Bolton, Richard D. (Los Alamos, NM)

    1999-01-01

    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.

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

    Microsoft Academic Search

    Daniel Cervera

    1997-01-01

    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

  9. Liquid/Gas Vortex Separator

    NASA Technical Reports Server (NTRS)

    Morris, B. G.

    1986-01-01

    Liquid/gas separator vents gas from tank of liquid that contains gas randomly distributed in bubbles. Centrifugal force separates liquid and gas, forcing liquid out of vortex tube through venturi tube. Gas vented through exhaust port. When liquid detected in vent tube, exhaust port closed, and liquid/gas mixture in vent tube drawn back into tank through venturi.

  10. Altération des sulfures des granulats dans les chaussées

    NASA Astrophysics Data System (ADS)

    Jigorel, A.; Jauberthie, R.

    2002-07-01

    Sulfides present in hornsfeld aggregates, used in light pavanent construction in contact with humid air alter rapidly. Crystallisation of sulfates at the interface of bitumastic material and sub-base creates serious problems (intumescence and crazing) that can lead to a total reconstruction of the project (roads, sidewalks, sports areas, etc). The sulfides in the aggregates and the sulfates produced due to alteration are studied by SEM and XRD. The results show that the intensity of this phenomenon is linked to the nature and the crystallinity of the sulfides. The evolution of the sulfates formed during this alteration process is slow and complex. In new pavements (3 years) the sulfates have a pulverised appearance and consist mostly of epsomite, associated with pickeringite and halotrichite. In older pavements (20 years) the sulfates form a fibrous concretion consisting of pickeringite and small quantities of halotrichite. Les sulfures présents dans les granulats élaborés à partir de cornéen nes s'altèrent rapidement dans les chaussées légères en présence d'air humide. La cristallisation des sulfates à l'interface enrobé-couche de fondation crée des désordres si importants (intumescences, faiençage) qu'il est bien souvent nécessaire d'assurer la réfection totale des ouvrages (routes, trottoirs, plateaux sportifs...). Les sulfures des granulats et les sulfates issus du processus d'altération ont été étudiés par diffractométrie X et examen su Microscope Electronique à Balayage équipé de microanalyse X. Les résultats montrent que !intensité des désordres est liée à la nature et à la cristallinité des sulfures. Les sulfates formés évoluent su cours du processus d'altération qui est long et complexe. Dans les chaussées récentes (3 ans) ils ont un aspect pulvérulent et sont constitués d'epsomite dominante associée à de la pickeringite et à de l'halotrichite. Dans les chaussées plus anciennes (20 ans) ils forment des concrétions fibreuses constituées de pickeringite et d'une faible quantité d'halotrichite.

  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. Duality of liquids.

    PubMed

    Trachenko, K; Brazhkin, V V

    2013-01-01

    Liquids flow, and in this sense are close to gases. At the same time, interactions in liquids are strong as in solids. The combination of these two properties is believed to be the ultimate obstacle to constructing a general theory of liquids. Here, we adopt a new approach: instead of focusing on the problem of strong interactions, we zero in on the relative contributions of vibrational and diffusional motion. We show that liquid energy and specific heat are given, to a very good approximation, by their vibrational contributions as in solids over almost entire range of relaxation time in which liquids exist as such, and demonstrate that this result is consistent with liquid entropy exceeding solid entropy. Our analysis therefore reveals an interesting duality of liquids not hitherto known: they are close to solids from the thermodynamic perspective and to flowing gases. We discuss several implications of this result. PMID:23851971

  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. Modélisation des boucles d'immunisation magnétique des navires

    NASA Astrophysics Data System (ADS)

    Le Dorze, F.; Bongiraud, J. P.; Coulomb, J. L.; Meunier, G.; Brunotte, X.

    1998-02-01

    This paper presents the problem of the three-dimensional modeling of degaussing coils in ships with a finite elements method. We show that these current coils are so close to the ferromagnetic sheets of the ship that they require a local very fine mesh which would be unrealistic for the whole complex structure of a real ship. We propose an alternative to the expensive mesh refinement called "reduced scalar potential jump”. The idea is to previously solve the local problem by another method and to use the result in the whole FEM modelling. We present the method of implementation in the FEM software FLUX3D and comparative results on a simple geometry. Cet article présente le problème de la modélisation en trois dimensions des boucles d'immunisation des navires par la méthode des éléments finis. Nous montrons que ces boucles de courant sont si proches des tôles ferromagnétiques du navire que leur modélisation requiert un maillage localement très fin, ce qui est irréaliste pour la structure complexe d'un navire réel. Nous proposons une alternative à ce coûteux affinage du maillage, appelée "saut de potentiel réduit”. L'idée est de résoudre au préalable le problème local par une autre méthode que les éléments finis et d'utiliser le résultat dans la modélisation globale. Nous présentons la méthode utilisée pour l'implantation de cette technique dans le logiciel d'éléments finis FLUX3D, et des résultats comparatifs sur une géométrie simple.

  15. Impact de l'augmentation de la volatilit des prix des commodits sur les coopratives Sabine TRGUER

    E-print Network

    Paris-Sud XI, Université de

    Impact de l'augmentation de la volatilité des prix des commodités sur les coopératives laitières Sabine TRÉGUER Janvier 2008 Résumé L'envolée actuelle des prix des matières premières agricoles a des, a augmenté de près de 70% en un an. Cette augmentation du prix des produits industriels laitiers, répercutée

  16. Belles captives : une histoire des zoos du ct des btes Eric Baratay

    E-print Network

    Boyer, Edmond

    Belles captives : une histoire des zoos du côté des bêtes Eric Baratay Les artistes ont beaucoup représenté les bêtes exposées dans les zoos, se passionnant pour leurs beautés, leurs formes (fig. 147'émergeaient des interrogations sur la légitimité des zoos. Max Slevogt (fig. 150) et Otto Dill (Tigres dans une

  17. Universit des sciences et technologies de Lille cole Doctorale des Sciences Pour l'Ingnieur

    E-print Network

    Paris-Sud XI, Université de

    Université des sciences et technologies de Lille École Doctorale des Sciences Pour l'Ingénieur Thèse pour obtenir le grade de Docteur de l'Université des sciences et technologies de Lille EN'université Droit et Santé de Lille (Lille II) M. Salah Maouche - Professeur à l'Université des Sciences et

  18. 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

  19. L'Observatoire Jacques-Yves Cousteau des mers et des ctes du Mexique

    E-print Network

    L'Observatoire Jacques-Yves Cousteau des mers et des côtes du Mexique a été lancé en coopération Mer des Caraïbes, sur le Golfe du Mexique et sur le Pacifique. Son objectif est de valoriser les nécessaire pour: Identifier l'origine des changements opérés aux différentes échelles temporelles

  20. LA DIFFUSION DES NEUTRONS Physique des Solides, Universit Paris-Sud, 91405 Orsay, France

    E-print Network

    Boyer, Edmond

    82 LA DIFFUSION DES NEUTRONS A. GUINIER Physique des Solides, Université Paris-Sud, 91405 Orsay, France Résumé. 2014 On rappellera les bases physiques de la diffusion des neutrons en insistant sur les des neutrons liées à leur faible absorption dans la matière et leur interaction avec les moments

  1. Composition en acides amins des aliments et des rsidus de fermentation in vitro

    E-print Network

    Paris-Sud XI, Université de

    Composition en acides aminés des aliments et des résidus de fermentation in vitro M. ANTONGIOVANNI in vitro fermentation with rumen inoculum, and of the faeces relative to an in vivo digestibility trial run fermentation in vitro comme l'ont fait Dennison et Philips (1983) et des fèces. Pour des raisons de place, nous

  2. Les limites de la couverture des risques en aquaculture : le cas des

    E-print Network

    Paris-Sud XI, Université de

    EA 4272 Les limites de la couverture des risques en aquaculture : le cas des conchyliculteurs en limites de la couverture des risques en aquaculture : le cas des conchyliculteurs en France Véronique Le in defining risks in aquaculture and we propose a classification that takes the specificities into account. We

  3. Rollstuhlbasketball Rolling Devils vs. Promi-Team Im Rahmen des Sporttages des UNISPORT fand in den frhen Abendstunden des

    E-print Network

    Pinnau, René

    Rollstuhlbasketball Rolling Devils vs. Promi-Team Im Rahmen des Sporttages des UNISPORT fand in den Rolling Devils und ein Promi-Team im Rollstuhlbasketball gegenüber. Für das Team der Rolling Devils und der Erstligaspieler Viktor. Des Weiteren rollten Lukas Jung und Paul Nikolaus für die Devils an

  4. 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....

  5. Pathologie vgtale Maladies des plantes dues Rhizoctonia

    E-print Network

    Paris-Sud XI, Université de

    Pathologie végétale Maladies des plantes dues à Rhizoctonia solani (Kühn) : stratégie et techniques; Plant diseases induced by Rhizoctonia solani (Kuhn) : strategy and methods of study. Results profession agricole demandant de résoudre des problèmes posés par Rhizoctonia solani ont notablement augmenté

  6. Funktionelle Kernspintomographie des Affengehirns Logothetis, Nikos

    E-print Network

    Funktionelle Kernspintomographie des Affengehirns Logothetis, Nikos Max-Planck-Institut für Korrespondierender Autor: Logothetis, Nikos E-Mail: nikos.logothetis@tuebingen.mpg.de Zusammenfassung Unsere hand, Tätigkeitsbericht 2003 Logothetis, Nikos | Funktionelle Kernspintomographie des Affengehirns 1

  7. Gomodlisation et Informatique : Formalisation des reprsentations et

    E-print Network

    Prié, Yannick

    -francois.rainaud@ifp.fr Laura S. Mastella Petrobras 330, Republica do Chile 20031 Rio de Janeiro Brésil laura.mastella@ petrobras.com.br RESUME Dans les projets d'ingénierie associant des experts métier et des informaticiens

  8. Jahresberichte 1992 und 1993 des Lehrstuhls

    E-print Network

    Weske, Mathias

    Jahresberichte 1992 und 1993 des Lehrstuhls ``Theoretische Informatik'' (Prof. Dr. sc. Christoph Meinel) Fachbereich IV -- Informatik Universit¨ at Trier Universit¨ atsring 15 D­54286 Trier #12; Jahresberichte 1992 und 1993 des Lehrstuhls ``Theoretische Informatik'' (Prof. Dr. sc. Christoph Meinel

  9. DPARTEMENT D'INFORMATIQUE Facult des sciences

    E-print Network

    Spino, Claude

    DÉPARTEMENT D'INFORMATIQUE Faculté des sciences GGuuiiddee ddeess ééttuuddeess ddee 22ee eett 33ee...............................................................................................................................3 1.1 Les études supérieures au Département d'informatique............................................................................................6 4 Gestion des études supérieures au Département d'informatique

  10. Über das sogenannte Bauchdeckenhämatom des vorgerückten Lebensalters

    Microsoft Academic Search

    K. Blond

    1924-01-01

    Ftir die subkutanen Rupturen der Artcria epigastric~ und ihrer Aste oder des Musculus rectus finder man in der Literatur keine einheitliche Nomenklatur. Der Symptomenkomplex ist unter den )\\/amen Spontanruptur des :Rectus abdominis, Ruptur der Arteria epigastric~ oder spontanes Bauehdeckenhs zusammengefa6t. Wohlgemuth nennt c[as Leiden subkutane Ruptur des Mttsculus rectus abdominis. Hilgenreiner spricht von dem spontanen Bauchdeckenh~tma~om des worgertickten Alters und

  11. Les attitudes des ménages : leur signification

    Microsoft Academic Search

    Philippe lHardy

    1976-01-01

    [fre] Les attitudes des ménages : leur signification - Instrument privilégié d'analyse conjoncturelle, l'enquête de l'INSEE sur les « attitudes et intentions d'achats des particuliers» cherche également à connaître l'opinion des ménages sur la situation économique française récente et future. A la lumière d'une expérience de plus de quinze années, l'auteur, rapprochant l'évolution observée des opinions émises, s'interroge sur la

  12. Histaminausschüttende und antiallergischen Wirkung des Insulinshocks

    Microsoft Academic Search

    Heinrich Bartelheimer; Theodor Afendulis

    1938-01-01

    Zusammenfassung  Nachdem von uns in früheren Versuchen festgestellt worden war, daß Insulinshocks den anaphylaktischen Shock des Meerschweinchens\\u000a aufheben oder ihn in hemmendem Sinne beeinflussen, ließ sich jetzt zeigen, daß diese antiallergische Wirkung nicht durch den\\u000a Eiweißcharakter des Insulins oder etwa vorhandene Begleitsubstanzen erfolgt. Auch eine hemmend wirkende Veränderung im Tonus\\u000a des vegetativen Nervensystems während des Insulinshocks konnte, wenigstens beim Meerschweinchen, unwahrscheinlich

  13. Rentre des tudiants UNIVERSIT BLAISE PASCAL

    E-print Network

    Sart, Remi

    Rentrée des étudiants étrangers UNIVERSIT� BLAISE PASCAL www.univ-bpclermont.fr COMMUNIQU� DE PRESSE Accueil des étudiants étrangers de l'Université Blaise Pascal Les échanges internationaux, chaque année, l'université Blaise Pascal envoie des étudiants à l'étranger et accueille des étudiants d

  14. Neurologie et neuropathologie des tigres en captivité

    Microsoft Academic Search

    Ludo Bogaert; Amico Bignami

    1964-01-01

    1.Chez un tigre adulte, on a observé des signes de néphrite avec crises d'épilepsie, peut être des hallucinations visuelles, des mouvements de manège, un nystagmus, un syndrome méningé à prédominance cervico-thoracique avec opisthotonos et finalement une paralysie de l'avant-train. Il existait un engainement des vaisseaux rétiniens sans exsudats. Evolution en dix semaines avec cachexie importante.2.A l'examen anatomique: méningoencéphalite avec épendymite

  15. Le prix des attributs du logement

    Microsoft Academic Search

    Jean Cavailhès

    2005-01-01

    [fre] La méthode des « prix hédonistes » permet d'estimer le prix des différents attributs d'un logement (taille, confort, environnement proche ou lointain, etc.) à partir de son prix global. De tels prix ont été estimés pour 1996 pour le secteur locatif libre des villes, de leurs banlieue et de leurs couronnes périurbaines(« aires urbaines »). Ainsi, la surface habitable

  16. Remise des Prix du recteur 2013 Flicitations

    E-print Network

    Parrott, Lael

    Communiqué Remise des Prix du recteur 2013 Félicitations à Lorraine Vaillancourt, Prix Initiative, et à l'équipe de production des Affaires publiques, Prix Coup de coeur ! La direction, le corps de la Faculté qui ont été couronnés lors de la récente remise des Prix du recteur, tenue ce mercredi

  17. N. Gorse Oct. 2003 Gestion des Processus

    E-print Network

    Mignotte, Max

    N. Gorse ­ Oct. 2003 Gestion des Processus Introduction à UNIX N. Gorse ­ Oct. 2003Introduction à ordonnanceur N. Gorse ­ Oct. 2003Introduction à UNIX 71 Gestion des Processus Définitions Processus (job, tâche mémoire N. Gorse ­ Oct. 2003Introduction à UNIX 72 Gestion des Processus Définitions Composition de l

  18. 2. PERTURBATIONS ET RECUPERATION DES FONCTIONS COGNITIVES

    E-print Network

    Paris-Sud XI, Université de

    2. « PERTURBATIONS ET RECUPERATION DES FONCTIONS COGNITIVES CHEZ LE SUJET NORMAL ET CHEZ LE SUJET «Perturbations et récupération des fonctions cognitives chez le sujet normal et chez le sujet pathologique». Ce présenter des dysfonctionnements de la cognition en dehors de toute pathologie avérée. Ces

  19. CONSEIL GENERAL DES CTES D'ARMOR

    E-print Network

    Boyer, Edmond

    CONSEIL GENERAL DES CÔTES D'ARMOR LUTTE PREVENTIVE ET CURATIVE CONTRE LA PROLIFERATION DES MAREES-Michel-en-Grève (Côtes d'Armor) _________ GEOMER ­ LETG UMR 6554 C.N.R.S. Janvier 2005 hal-00271248,version1-12Aug2014 #12;Poche du Yar 2003-2004 ­ GEOMER-UMR 6554 CNRS -1- CONSEIL GENERAL DES COTES D'ARMOR LUTTE

  20. 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).

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

    E-print Network

    Brauner, Neima

    with a complete separation of the liquids may prevail for some limited range of relatively low flow rates where2.22.2323 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

  2. A EPR Study of Glass Forming Liquids and Liquid Crystals

    Microsoft Academic Search

    Johanan Isaac Spielberg

    1985-01-01

    This study has made use of electron paramagnetic resonance (EPR) probe techniques to explore the liquid phase, the supercooled liquid, the glass transition and the glass phase of isotropic and ordered liquid crystalline organic glass formers. Some surprising insights into supercooled liquid and glass state dynamics were discovered. Studies of an organic glass forming liquid, dibutyl phthalate, show a change

  3. Low Toxic Ionic Liquids, Liquid Catanionics, and Ionic Liquid Microemulsions

    Microsoft Academic Search

    Werner Kunz; Eva Maurer; Regina Klein; Didier Touraud; Doris Rengstl; Agnes Harrar; Susanne Dengler; Oliver Zech

    2011-01-01

    In the future the demand of sustainable and low toxic surfactants and solvents will constantly increase. In this article, we present some new approaches to meet these requirements. Whereas ionic liquids are often based on imidazolium ions, we will show that there are also much less toxic ones, especially with choline as cation. Choline salts, even if solid at room

  4. Liquid environmental stress screening

    NASA Astrophysics Data System (ADS)

    Walker, J. L.

    1992-05-01

    This report describes a method of performing Environmental Stress Screening in an inert fluid. Because the liquid has a high dielectric strength, the items being screened can be energized and operational while submerged. Transmitting vibrations through the liquid to the item being screened permits screening without the use of fixtures, and the liquid's high heat capacity allows very rapid temperature changes, either by pumping hot or cold liquid from remote reservoirs or by moving the device from a hot tank to a cold tank. A prototype screening system has been built at NRaD, and faults induced in a small (47 pieces) lot of printed wiring boards have been detected.

  5. 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.

  6. 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.

  7. Etude des Abondances de MG et de fe dans la Composante Stellaire des Disques des Galaxies Spirales

    NASA Astrophysics Data System (ADS)

    Beauchamp, Dominique

    Je presente ici une technique d'observation par imagerie des disques stellaires des galaxies spirales. Je tente, a l'aide d'un modele evolutif multiphase, de determiner les abondances de fer et de magnesium dans les disques. Dans ce but, je mesure les indices Mg2 et Fe5270 du systeme de Lick. Ces elements representent un choix judicieux d'indicateurs car ils sont formes par des supernovae de deux types differents ayant des durees de vie differentes. Le rapport d'abondances de ces deux elements est un indicateur du taux de formation des populations stellaires. Je decris, en premier lieu, les observations, la technique de mesure, ainsi que son application. J'analyse ensuite les indices mesures. A partir du modele multiphase, j'explore differents parametres physiques des spirales comme le taux de formation stellaire, l'evolution des abondances, les effets possibles de la presence de la barre, etc.

  8. Liquid crystals on modified surfaces

    Microsoft Academic Search

    Ishtiaque Moyeen Syed

    2006-01-01

    Although covering several diverse topics, the most common theme of this thesis is the control and understanding of liquid crystal phenomena at a non liquid crystal alignment layer. Experiments were performed to study different surface induced effects in liquid crystals. A polymer liquid crystal aligning layer was modified so that there is a non-zero tilt angle of the liquid crystal

  9. Plan de cours Facult des arts et des sciences

    E-print Network

    Parrott, Lael

    ., Richard, D. Les Cordés: anatomie comparée des Vertébrés, 9e éd. (2009) Hildebrand, M. & Goslow, G. Analysis of Vertebrate Structure, 5th ed. (2001) Kardong, KV. Vertebrates: Comparative Anatomy, Function, Evolution, 5th Ed. McGraw Hill (2008) Liem, K., Bemis, W., Walker, WF., Grande, L. Functional Anatomy

  10. Plan de cours Facult des arts et des sciences

    E-print Network

    Parrott, Lael

    Cordés: anatomie comparée des Vertébrés, 9e éd. (2009) Hildebrand, M. & Goslow, G. Analysis of Vertebrate Structure, 5th ed. (2001) Kardong, KV. Vertebrates: Comparative Anatomy, Function, Evolution, 5th Ed. McGraw Hill (2008) Liem, K., Bemis, W., Walker, WF., Grande, L. Functional Anatomy of the Vertebrates

  11. UNIVERSIT DE NANTES FACULT DES SCIENCES ET DES TECHNIQUES

    E-print Network

    Paris-Sud XI, Université de

    naturelle sur la reconnaissance des roches par télédétection V-IR : application à la cartographie de l'ophiolite............................................................. 51 2.2 Contexte géologique de l'ophiolite d ..................................................................................................................................... 54 2.2.2 Formation de l'ophiolite et unités lithologiques affleurant dans les montagnes d

  12. VALUATION EMPIRIQUE DES IMPACTS DES VNEMENTS AYANT ABOUTI

    E-print Network

    Paris-Sud XI, Université de

    toujours été appliqués par les entreprises françaises, est l'utilisation de la juste valeur comme principal. Notamment celles examinant l'effet de la comptabilité en juste valeur (i.e. : Barth, Landsman & Whalen (1995'allait représenter la mise en oeuvre des normes IAS/IFRS et notamment IAS 39, celle qui a suscité le plus de

  13. Dpartement de communication Facult des arts et des sciences

    E-print Network

    Parrott, Lael

    'occasion de tester et d'évaluer ses connaissances acquises en communication au Département dans le cadre d'étudiant doit être en mesure : d'évaluer ses habilités et ses compétences personnelles en communication; d'estimer la portée de ses connaissances, de ses aptitudes et de ses compétences vis-à-vis des exigences du

  14. Dpartement de communication Facult des arts et des sciences

    E-print Network

    Parrott, Lael

    'évaluer ses connaissances acquises en communication au Département dans le cadre d'une expérience concrète en : · d'évaluer ses habilités et ses compétences personnelles en communication; · d'estimer la portée de ses connaissances, de ses aptitudes et de ses compétences vis-à-vis des exigences du milieu

  15. Facult des arts et des sciences Dpartement de science politique

    E-print Network

    Parrott, Lael

    politique et politique comparée. Chaque champ dispose, en principe, de ses objets et de ses angles d'analyse privilégiés. La politique comparée est un des champs de la science politique. Cependant, si elle a ses objets la science politique avec ses méthodes propres, ses objets d'analyse et ses auteurs de référence. C

  16. Dpartement de communication Facult des arts et des sciences

    E-print Network

    Parrott, Lael

    'évaluer ses connaissances acquises en communication au Département dans le cadre d'une expérience concrète en : d'évaluer ses habiletés et ses compétences personnelles en communication; d'estimer la portée de ses connaissances, de ses aptitudes et de ses compétences vis-à-vis des exigences du milieu

  17. Techniken & Sprachen des Semantic Web Techniken & Sprachen des Semantic Web

    E-print Network

    Pfeifer, Holger

    World Wide Web (7) Tim Berners-Lee Proposal 1989: Hypertextsystem als Infrastrukturprinzp f Berners-Lee) 1989: An intriguing possibility, given a large hypertext database with typed links, Inst. f¨ur KI, Uni Ulm 3 - 10 Techniken & Sprachen des Semantic Web Aber ... CERN Proposal, (Tim

  18. II. DIGESTION DES PROTINES ET ABSORPTION INTESTINALE DES ACIDES AMINS

    E-print Network

    Paris-Sud XI, Université de

    'influence de la flore du tube digestif du monogastrique a été mise en évidence depuis plusieurs années au Laboratoire des Métabolismes du C.N.R.Z. La flore intes- tinale peut en effet désaminer ou décarboxyler les la présente action concer- tée et, en conséquence, ne sont rappelées ici que pour mémoire (cf. MICHEL

  19. Plan de cours Facult des arts et des sciences

    E-print Network

    Parrott, Lael

    fonctions des molécules du vivant ; expliquer la relation ADN - ARN - protéine ; connaître l'historique de C. Acides nucléiques Acides désoxyribonucléiques [ADN] Acides ribonucléiques [ARN] Réplication de l'ADN D. Transcription et traduction : synthèse protéique Transcription de l'ADN en ARN Traduction

  20. 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

  1. Chiral separation by enantioselective liquid-liquid extraction.

    PubMed

    Schuur, Boelo; Verkuijl, Bastiaan J V; Minnaard, Adriaan J; de Vries, Johannes G; Heeres, Hero J; Feringa, Ben L

    2011-01-01

    The literature on enantioselective liquid-liquid extraction (ELLE) spans more than half a century of research. Nonetheless, a comprehensive overview has not appeared during the past few decades. Enantioselective liquid-liquid extraction is a technology of interest for a wide range of chemists and chemical engineers in the fields of fine chemicals, pharmaceuticals, agrochemicals, fragrances and foods. In this review the principles and advances of resolution through enantioselective liquid-liquid extraction are discussed, starting with an introduction on the principles of enantioselective liquid-liquid extraction including host-guest chemistry, extraction and phase transfer mechanisms, and multistage liquid-liquid extraction processing. Then the literature on enantioselective liquid-liquid extraction systems is reviewed, structured on extractant classes. The following extractant classes are considered: crown ether based extractants, metal complexes and metalloids, extractants based on tartrates, and a final section with all other types of chiral extractants. PMID:21107491

  2. Nonequilibrium liquid theory for sheared granular liquids

    NASA Astrophysics Data System (ADS)

    Hayakawa, Hisao; Chong, Song-Ho; Otsuki, Michio

    2010-05-01

    A nonequilibrium liquid theory for uniformly sheared granular liquids is developed starting from SLLOD equations. We derive a generalized Green-Kubo formula and demonstrate that it yields the nonequilibrium steady-state average which is essentially independent of the choice of the initial condition. It is also shown that the fluctuating hydrodynamics can be derived from Mori-type equations for density and current-density fluctuations if one considers a weak-shear and small-dissipation limit along with the Markovian approximation.

  3. Synthesis of ionic liquids

    DOEpatents

    Dai, Sheng (Knoxville, TN); Luo, Huimin (Knoxville, TN)

    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.

  4. 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.

  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. In situ ionic-liquid-dispersive liquid-liquid microextraction of Sudan dyes from liquid samples.

    PubMed

    Xu, Bo; Song, Daqian; Wang, Yuanpeng; Gao, Yan; Cao, Bocheng; Zhang, Hanqi; Sun, Ying

    2014-08-01

    In situ ionic-liquid-dispersive liquid-liquid microextraction was introduced for extracting Sudan dyes from different liquid samples followed by detection using ultrafast liquid chromatography. The extraction and metathesis reaction can be performed simultaneously, the extraction time was shortened notably and higher enrichment factors can be obtained compared with traditional dispersive liquid-liquid microextraction. When the extraction was coupled with ultrafast liquid chromatography, a green, convenient, cheap, and efficient method for the determination of Sudan dyes was developed. The effects of various experimental factors, including type of extraction solvent, amount of 1-hexyl-3-methylimidazolium chloride, ratio of ammonium hexafluorophosphate to 1-hexyl-3-methylimidazolium chloride, pH value, salt concentration in sample solution, extraction time and centrifugation time were investigated and optimized for the extraction of four kinds of Sudan dyes. The limits of detection for Sudan I, II, III, and IV were 0.324, 0.299, 0.390, and 0.655 ng/mL, respectively. Recoveries obtained by analyzing the seven spiked samples were between 65.95 and 112.82%. The consumption of organic solvent (120 ?L acetonitrile per sample) was very low, so it could be considered as a green analytical method. PMID:24840862

  7. Liquid Crystal Thermometers

    NSDL National Science Digital Library

    Paul Doherty

    1999-01-01

    In this activity, learners explore liquid crystal thermometers to observe how heat flows by conduction, convection, radiation, and evaporation. This resource includes five mini-explorations in which learners use basic materials and observe color changes on a liquid crystal thermometer card.

  8. 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)

  9. Tunable liquid crystal lasers

    NASA Astrophysics Data System (ADS)

    Woltman, Scott J.

    Liquid crystal lasers are dye-doped distributed feedback lasing systems. Fabricated by coupling the periodic structure of a liquid crystal medium with a fluorescent dye, the emission from these systems is tunable by controlling the liquid crystal system---be it through electric or thermal field effects, photochemical reactions, mechanical deformations, etc. The laser action arises from an extended interaction time between the radiation field, the laser emission, and the matter field, the periodic liquid crystal medium, at the edge of the photonic band gap. In this thesis, several tunable liquid crystal laser systems are investigated: cholesteric liquid crystals, holographic-polymer dispersed liquid crystals and liquid crystal polarization gratings. The primary focus has been to fabricate systems that are tunable through electrical means, as applications requiring mechanical or thermal changes are often difficult to control. Cholesteric liquid crystal lasers are helical Bragg reflectors, with a band gap for circularly polarized light of equivalent handedness to their helix. These materials were doped with a laser dye and laser emission was observed. The use of an in-plane electric field tends to unwind the helical pitch of the film and in doing so tunable emission was demonstrated for ˜15 nm. Holographic-polymer dispersed liquid crystals (H-PDLCs) are grating structures consisting of alternating layers of polymer and liquid crystal, with different indices of refraction. The application of an electric field index matches these layers and switches off the grating. Thus, laser emission can be switched on and off through the use of an electric field. Spatially tunable H-PDLC lasers were fabricated by creating chirped gratings, formed by divergent beams. The emission was shown to tune ˜5 nm as the pump beam was translated across a 1 inch film. Liquid crystal polarization gratings use photo-patterned alignment layers, through a polarization holography exposure, to induce an alignment in a liquid crystal film. Electrically tunable emission was demonstrated in these systems. Applications of liquid crystal lasers include emissive substrates or backplanes for displays or tunable emission sources for biology and medicine. The potential for such applications are discussed.

  10. Renewable liquid reflecting zone plate

    SciTech Connect

    Toor, Arthur; Ryutov, Dmitri D.

    2003-12-09

    A renewable liquid reflecting zone plate. Electrodes are operatively connected to a dielectric liquid in a circular or other arrangement to produce a reflecting zone plate. A system for renewing the liquid uses a penetrable substrate.

  11. Conception des IHM Fabien Duchateau

    E-print Network

    Jean-Daubias, Stéphanie

    ) : confusion d'affichage des unités sur un cadran d'altimétrie Accident nucléaire de Three Mile Island (1979) : absence de prise en compte de la dimension humaine dans le processus de supervision http://en.wikipedia.org/wiki/Three_Mile_Island

  12. REVUE BIBLIOGRAPHIQUE EFFICACITE DES ANTIBIOTIQUES

    E-print Network

    Paris-Sud XI, Université de

    of the efficiency of antibiotics against bovine mastitis has been reviewed. Criteria for the choice of papersREVUE BIBLIOGRAPHIQUE EFFICACITE DES ANTIBIOTIQUES CONTRE LES MAMMITES BOVINES STAPHYLOCOCCIQUES ET. Introduction. De nombreux remèdes ont été essayés contre les mammites bovines depuis l'acide borique (Nocard et

  13. Die Macht des Krokodils1

    Microsoft Academic Search

    ANGELIKA LOHWASSER

    In der ägyptischen Mythologie hat das Krokodil einen höchst ambivalenten Charakter. Einerseits ist es das gefährliche Ungeheuer, das den Menschen im und am Nil tötet, andererseits wurde es in verschiedenen Regionen göttlich verehrt. Die Verehrung dürfte vor allem eine Besänftigung des Raubtieres zum Ziel haben - die Furcht vor dem todbringenden Wassertier bewirkte den Glauben an ein göttliches Wesen, dessen

  14. Journes Nationales des Cristaux pour

    E-print Network

    Canet, Léonie

    organisée par le Réseau CNRS-CMDO + « Cristaux Massifs, Micro-nano-structures et Dispositifs pour l nationales, les quatrièmes du genre, portent sur la méthodologie et la technologie dans les domaines de l'élaboration, de la mise en forme, de la micro-nano-structuration et de la caractérisation des cristaux pour l

  15. Habilitation Diriger des Recherches Prsente

    E-print Network

    Examinateur Colette Rolland Directeur tel-01003149,version1-10Jun2014 #12;tel-01003149,version1 celui des autres navires que j'ai pu croiser. Avant tout, je tiens à remercier le Professeur Colette ans, Colette m'a donné le modèle exceptionnel d'un esprit brillant, clairvoyant, dynamique, tenace. Sa

  16. DIVISION INFORMATIQUE Facult des lettres

    E-print Network

    Halazonetis, Thanos

    DIVISION INFORMATIQUE Faculté des lettres Inscriptions en ligne I E L 1/ aux cours et 2/ aux examens #12;DIVISION INFORMATIQUE 19.09.20112 · inscriptions aux cours dès la 2e (ou 3e) semaine du annoncées dès la rentrée sur le site de la Faculté Dates-clés #12;DIVISION INFORMATIQUE 19.09.20113 Le

  17. association des naturalistes de la

    E-print Network

    Paris-Sud XI, Université de

    du dimanche 25 avril 2004 Argiles kaoliniques et terres à foulon de la région de Provins : à la Lozère Calc. de Champigny Sable de Fontainebleau Calc. de St-Ouen Calcaire de Provins Sable d Argiles Plastiques de Provins du Sparnacien sont des dépôts continentaux de la base du Tertiaire, déposés

  18. Application of Ionic Liquids in Liquid Chromatography

    Microsoft Academic Search

    Micha? Piotr Marsza??; Roman Kaliszan

    2007-01-01

    Interest in ionic liquids (ILs) for their potential application in analytical chemistry continues to grow. Their usefulness can be due to favourable physicochemical properties, like the lack of vapour pressure, good thermal and chemical stability as well as very good dissolution properties regarding both organic and inorganic compounds. A specific feature of ILs is that these compounds provide strong proton

  19. 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.

  20. LES PROPRITS ACOUSTIQUES DES VERRES ISOLANTS A BASSE TEMPRATURE

    E-print Network

    Paris-Sud XI, Université de

    809 LES PROPRIÉTÉS ACOUSTIQUES DES VERRES ISOLANTS A BASSE TEMPÉRATURE P. DOUSSINEAU Laboratoire d verres isolants présentent à basse température des propriétés différentes de celles des cristaux. La couplage mesurés, l'utilisation des ondes acous- tiques permet l'étude de certaines propriétés des verres

  1. AU NORD DES BORGIA LA FAMILLE JOUFFROY ET

    E-print Network

    Paris-Sud XI, Université de

    AU NORD DES BORGIA LA FAMILLE JOUFFROY ET L'INTRODUCTION DE L'ART ITALIEN DE LA RENAISSANCE DANS L'auteur des célèbres décorations des appartements Borgia au Vatican et l'un des maît- 1 n° 222 -- Été 2011 La pape Alexandre VI Borgia au Vatican (v. 1494) tant ils présentent des similitudes qui ne peuvent pas

  2. ANALYSE DES DETERMINANTS DE LA GESTION DES RESULTATS : CAS DES FIRMES CANADIENNES FRANCAISES ET TUNISIENNES

    E-print Network

    Paris-Sud XI, Université de

    2011 Manuscrit auteur, publié dans "COMPTABILITE, CONTROLE, AUDIT ET INSTITUTION(S), Tunisie (2006 excessive est fortement déterminée par des motivations contextuelles rattachées à un marché financier to the Anglo-American and Euro-Continental accounting models. Canada and France, respectively, belong to those

  3. 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.

  4. 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.

  5. L'impact des normes IFRS sur la performance et le risque des compagnies d'assurance

    E-print Network

    Boyer, Edmond

    1 L'impact des normes IFRS sur la performance et le risque des compagnies d'assurance Jean IFRS, et en particuliers la comptabilisation des actifs à leur juste valeur et non plus au coût'impact de l'introduction des normes IFRS, notamment l'IAS 39, sur la performance financière et le risque des

  6. Le cycle des mares pourrait amplifier l'lvation du niveau des mers lie au rchauffement climatique

    E-print Network

    W Le cycle des marées pourrait amplifier l'élévation du niveau des mers liée au réchauffement climatique est l'élévation du niveau des mers liée à l'aug- mentation de la tem- pérature de l'océan, ce, le cycle des marées influence égale- ment la variation du ni- veau des mers. A partir d

  7. Liquid-level detector

    DOEpatents

    Not Available

    1981-01-29

    Aliquid level sensor is described which has 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.

  8. 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.

  9. Liquid propellant rockets.

    NASA Technical Reports Server (NTRS)

    Dipprey, D. F.

    1972-01-01

    A brief overview of the state of knowledge in liquid rocket technology is presented and examples are provided of instances where some fundamental principles of chemistry, fluid mechanics, and mathematics can be applied. A liquid propellant rocket classification is discussed together with rocket system performance, applications for liquid propellants, the effective exhaust velocity, aspects of simplified nozzle expansion, questions about theoretical propellant performance, the effect of chamber pressure on equilibrium performance, and the kinetic recombination in nozzles. Details of propellant combustion are examined, giving attention to propellant injection, evaporation-controlled combustion, combustion instability, and monopropellant decomposition.

  10. 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.

  11. Exploring Materials: Liquid Crystals

    NSDL National Science Digital Library

    Nanoscale Informal Science Education Network

    2010-01-01

    In this activity, learners discover that the way a material behaves on the macroscale is affected by its structure on the nanoscale. Learners investigate the properties of a heat sensitive liquid crystal and make their own liquid crystal sensor to take home. This is a fun and engaging activity, especially since liquid crystals are used in many consumer products, including cell phone displays, laptop computer screens, strip thermometers, and even "mood" rings! SAFETY: learners must be supervised when doing this activity. They must wear safety glasses to protect their eyes. Before doing this activity, read through the Material Safety Data Sheets.

  12. Liquid thickness gauge

    NASA Astrophysics Data System (ADS)

    Weinstein, Leonard M.

    1988-08-01

    A method and apparatus are developed to measure the thickness of a liquid on a surface independent of liquid conductivity. Two pairs of round, corrosion resistant wires are mounted in an insulating material such that the cross-sectional area of each wire is flush with and normal to the surface. The resistance between each pair of wires is measured using two ac resistance measuring circuits, in which the ratio of the outputs of the two resistance measuring circuits is indicative of the thickness of the liquid on the surface.

  13. 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

  14. Association Francophone de Comptabilit Tunis 2006 Raction des analystes financiers la publication des informations

    E-print Network

    Boyer, Edmond

    Association Francophone de Comptabilité Tunis 2006 1 Réaction des analystes financiers à la (2006)" #12;Association Francophone de Comptabilité Tunis 2006 2 Réaction des analystes financiers à la

  15. Morale et technique : la fin des Bruno Latour, CSI, Ecole des mines

    E-print Network

    Paris-Sud XI, Université de

    Morale et technique : la fin des moyens Bruno Latour, CSI, Ecole des mines Article préparé pour le et demi d'années (Latour et Lemonnier, 1994). On commence maintenant, après les travaux pionniers sur

  16. Direction des Ressources Humaines Service des Personnels Administratifs et

    E-print Network

    Sart, Remi

    logistique » CORPS : ATRF NATURE : AFFECTATION ETABLISSEMENT : Université Blaise Pascal ­ IUFM d'Auvergne, Université Blaise Pascal. Il est basé à Chamalières. La tâche principale sera d'assurer l'entretien des Responsable administrative de l'IUFM d'Auvergne, Université Blaise Pascal Tel : 04 73 31 71 52 #12;

  17. 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.

  18. 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

  19. 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

  20. Sur l'infimum des parties reelles des zeros des sommes partielles de la fonction z^eta de Riemann

    E-print Network

    Paris-Sud XI, Université de

    Sur l'infimum des parties r´eelles des z´eros des sommes partielles de la fonction z^eta de Riemann ) (on ne consid`ere ici que les z´eros r´eels). Observons d`es maintenant que k n,k est d´eries de Dirichlet ordinaires f(s) = m=1 a(m) ms et g(s) = m=1 b(m) ms sont dites ´equivalentes s

  1. motrice du couple. J'ai d'ailleurs remarqu que le zinc orclinaire donne partout des rsultats plus variables que le zinc amalgam.

    E-print Network

    Paris-Sud XI, Université de

    449 motrice du couple. J'ai d'ailleurs remarqué que le zinc orclinaire donne partout des résultats plus variables que le zinc amalgamé. Le liquide que j'ai choisi, au moins provisoirement, est la dis. La force électromotrice du couple zinc amalgamé-cuivre-eau salée est 0volt, 82 entre + 5° C. et + 40

  2. 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.

  3. 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

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

    SciTech Connect

    None

    2011-02-14

    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.

  5. Répartitions modales urbaines, externalités et instauration de péages. Le cas des externalités de congestion et des \\

    Microsoft Academic Search

    François Mirabel

    1999-01-01

    [fre] Répartitions modales urbaines, externalités et instauration de péages. Le cas des externalités de congestion et des « externalités modales croisées ». . Cet article se propose d'analyser les répartitions des usagers entre l'automobile et les bus dans le cadre des déplacements urbains domicile-travail. Dans ce contexte, l'objectif de cet article est de mettre en lumière deux types d'externalités générées

  6. Environnement des Systèmes Binaires Jeunes

    NASA Astrophysics Data System (ADS)

    Duchene, Gaspard

    2000-07-01

    La fréquence élevée des systèmes binaires, tant parmi les étoiles de la séquence principale que dans les régions de formation stellaire, a été largement mise en évidence au cours des dix dernières années. Cette constatation soulève naturellement la question de la nature du processus responsable de la formation préférentielle de ces systèmes multiples. Par ailleurs, les phénomènes d'interaction entre un compagnon et l'environnement complexe d'une étoile T Tauri sont encore trèsmal compris. C'est dans ce cadre que se place le travail conduit durant cette thèse, dont les principaux objectifs sont: i) la détermination de la fraction de binaires dans différentes populations pré-séquence principale, ii) l'étude quantitative du phénomène d'accrétion dans les systèmes binaires T Tauri, et iii) l'observation directe et la modélisation de disques circumstellaires et circumbinaires. Dans le cadre d'une recherche de binaires visuelles à l'aide du système d'optique adaptative du Télescope Canada-France-Hawaii, j'ai pris part à l'observation de plusieurs centaines d'objets situés dans différents amas stellaires jeunes. Je détaille ici l'analyse et les résultats concernant deux amas âgés de moins de deux millions d'années. Lorsqu'on considère l'ensemble des populations étudiées jusqu'à présent, on constate que la proportion de binaires visuelles parmi les étoiles de type solaire est la même dans les amas stellaires que sur la séquence principale. De plus, cette propriété ne dépend pas de l'âge de l'amas, ce qui implique que la fraction de binaires n'évolue pas après le premier million d'années dans ces amas. A l'opposé, les zones de formation peu denses, qui sont toutes très jeunes, possèdent une proportion de binaires sensiblement plus élevée. Les modèles les plus à même de reproduire ces observations sont ceux selon lesquels la fraction de binaires qui résulte de l'effondrement gravitationnel est proche de 100%. Dans les amas les plus denses, cette fraction peut ensuite être rapidement réduite du fait des nombreuses interactions gravitationnelles destructrices entre systèmes proches. D'autres interprétations restent toutefois envisageables. Je m'intéresse ensuite au phénomène d'accrétion dans les binaires T Tauri par la spectroscopie visible des composantes de ces systèmes. Cette approche révèle que le phénomène d'accrétion perdure aussi longtemps sur les deux composantes d'une même binaire. De plus, la comparaison des luminosités émises dans la raie H? montre que le primaire présente généralement le taux d'accrétion le plus élevé. Une interprétation possible de ces observations est que ces binaires possèdent des réservoirs circumbinaires de matière, probablement sous la forme d'une vaste enveloppe, qui alimentent simultanément les deux disques circumstellaires. Enfin, je présente des images à haute résolution angulaire des disques circumbinaires de GG Tau et UY Aur et des disques circumstellaires de HK Tau B et HV Tau C. Ces observations, obtenues dans le visible, le proche infrarouge et le domaine radio, permettent une description fine de l'environnement de ces binaires. Je détaille également l'analyse de cartes de polarisation des deux disques circumbinaires obtenues à 1 micron. Afin de déterminer les propriétés géométriques de ces disques et celles des grains de poussière qui s'y trouvent, j'ai entrepris une modélisation de la diffusion multiple de la lumière en utilisant une approche Monte-Carlo. Cette étude indique que l'anneau circumbinaire de GG Tau est géométriquement épais (avec un rapport d'aspect h/r~0.18), qu'il comporte des grains de poussière très petits (<1 micron) et que la masse totale de poussière dans l'anneau est au moins 10-3 masses solaires. L'environnement de UY Aur apparaît beaucoup plus complexe que celui de GG Tau: le disque circumbinaire, dont l'inclinaison est ré-évaluée à environ 60 degrés, coexiste avec un filament situé à proximité mais distinct, et plusieurs "branches&qu

  7. 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

  8. Ionic liquids in tribology.

    PubMed

    Minami, Ichiro

    2009-01-01

    Current research on room-temperature ionic liquids as lubricants is described. Ionic liquids possess excellent properties such as non-volatility, non-flammability, and thermo-oxidative stability. The potential use of ionic liquids as lubricants was first proposed in 2001 and approximately 70 articles pertaining to fundamental research on ionic liquids have been published through May 2009. A large majority of the cations examined in this area are derived from 1,3-dialkylimidazolium, with a higher alkyl group on the imidazolium cation being beneficial for good lubrication, while it reduces the thermo-oxidative stability. Hydrophobic anions provide both good lubricity and significant thermo-oxidative stability. The anions decompose through a tribochemical reaction to generate metal fluoride on the rubbed surface. Additive technology to improve lubricity is also explained. An introduction to tribology as an interdisciplinary field of lubrication is also provided. PMID:19553900

  9. Fractons and Luttinger liquids

    E-print Network

    Wellington da Cruz

    2000-10-05

    We consider the concept of fractons as particles or quasiparticles which obey a specific fractal statistics in connection with a one-dimensional Luttinger liquid theory. We obtain a dual statistics parameter ${\\tilde{\

  10. Liquid Phase Heating Systems 

    E-print Network

    Mordt, E. H.

    1979-01-01

    Temperature Water (HTW) central district heating systems are far superior to steam systems in large, spread out installations such as airports, universities and office complexes. Water, pressurized to keep it in the liquid state, is distributed at 400o...

  11. Basic Liquid Chromatography

    NSDL National Science Digital Library

    Dr. Yuri Kazakevich

    This online textbook offers a variety of information on high performance liquid chromatography (HPLC). Topics covered include instruments, detectors, theory, column selection, and pH effect. This website also contains links to a glossary, useful links, and manufacturer websites.

  12. Diet - full liquid

    MedlinePLUS

    ... any solids in them or on top – things like nuts, chocolate chips, and pieces of cookies. Try having a mix of 5 to 7 of the foods you can eat for breakfast, lunch, and dinner. Liquid foods do NOT ...

  13. Liquidity and Trading Dynamics

    E-print Network

    Guerrieri, Veronica

    In this paper, we build a model where the presence of liquidity constraints tends to magnify the economy's response to aggregate shocks. We consider a decentralized model of trade, where agents may use money or credit to ...

  14. 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 ...

  15. Ionic liquid ethanol sensor.

    PubMed

    Lee, Yuan Gee; Chou, Tse-Chuan

    2004-07-30

    Ionic liquids containing lithium methylsulfonyl group were prepared from the precursors poly(propylene glycol)-block-(ethylene glycol)-block-(propylene glycol)-bis(2-aminopropyl ether) with different molecular weight. These liquids revealed excellent electrical conductivity in the temperature range -25 to 85 degrees C. Also, they exhibited a high boiling temperature and hence a low vapor pressure in ambient condition. Additionally, they showed a high fluidity with their viscosities being comparative with that of water. To determine the sensitivity of an ethanol sensor by using these ionic liquids, these liquids were subjected into a sequential electrochemical tests with nickel electrodes which performed a high sensitivity for the ethanol sensor. It was found that only the derivative with low molecular weight could detect ethanol. Furthermore, a linear relationship between the response current and the concentration of ethanol was constructed. The detection limit was found to be 0.13% (v/v) and its response time was 336 s. PMID:15142574

  16. Liquid rocket engine injectors

    NASA Technical Reports Server (NTRS)

    Gill, G. S.; Nurick, W. H.

    1976-01-01

    The injector in a liquid rocket engine atomizes and mixes the fuel with the oxidizer to produce efficient and stable combustion that will provide the required thrust without endangering hardware durability. Injectors usually take the form of a perforated disk at the head of the rocket engine combustion chamber, and have varied from a few inches to more than a yard in diameter. This monograph treats specifically bipropellant injectors, emphasis being placed on the liquid/liquid and liquid/gas injectors that have been developed for and used in flight-proven engines. The information provided has limited application to monopropellant injectors and gas/gas propellant systems. Critical problems that may arise during injector development and the approaches that lead to successful design are discussed.

  17. Dynamics of liquid nanofilms

    E-print Network

    Henri Gouin; Sergey Gavrilyuk

    2008-09-20

    The van der Waals forces across a very thin liquid layer (nanofilm) in contact with a plane solid wall make the liquid nonhomogeneous. The dynamics of such flat liquid nanofilms is studied in isothermal case. The Navier-Stokes equations are unable to describe fluid motions in very thin films. The notion of surface free energy of a sharp interface separating gas and liquid layer is disqualified. The concept of disjoining pressure replaces the model of surface energy. In the nanofilm a supplementary free energy must be considered as a functional of the density. The equation of fluid motions along the nanofilm is obtained through the Hamilton variational principle by adding, to the conservative forces, the forces of viscosity in lubrication approximation. The evolution equation of the film thickness is deduced and takes into account the variation of the disjoining pressure along the layer.

  18. Liquid Assets: Wastewater

    NSDL National Science Digital Library

    2008-11-20

    This video segment from a WPSU documentary Liquid Assets describes the progression of wastewater management from its early days to present day wastewater treatment systems. The development of Boston’s first-ever waste management system is described.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. Compact Liquid Deaerator

    NASA Technical Reports Server (NTRS)

    Yamauchi, S. T.

    1982-01-01

    Gases are removed from liquids by a new deaerator that takes up only 5 inches (12.7 cm) at top of a medium-sized storage tank. Deaerator has a multiple cascading header that exposes more fluid at lower pressures than typical commercial deaerators. Potential applications are in hydraulic systems for aircraft and heavy machinery, in cooling systems where deaerated liquid is needed to prevent cavitation of pump.

  4. Photorheological ionic liquids.

    PubMed

    Avó, João; Cidade, M T; Rodriguez, Vincent; Lima, João C; Parola, A Jorge

    2015-06-01

    Two room temperature ionic liquids (ILs) bearing coumarin and p-hydroxycinnamic acid moieties are synthesized, and their photochemistry is studied in solution and neat conditions. Irradiation at absorption maxima leads to photochemical transformations and results in changes of their rheological properties which are evaluated by rotational rheometry. Samples of ionic liquids are also studied by Hyper-Rayleigh scattering, and the effect of their photochemistry on ionic nanoaggregation is discussed. PMID:25970078

  5. Etude des particularits de la poule Fayoumi. III. Ponte, caractristiques des œufs, efficacit alimentaire

    E-print Network

    Paris-Sud XI, Université de

    Etude des particularités de la poule Fayoumi. III. Ponte, caractéristiques des œufs, efficacité alimentaire et paramètres physiologiques de poules Fayoumi, Rhode-Island et F1 en batteries P'Hygiène alimentaire, F 22440 Ploufragan Résumé Des poules de la race Egyptienne Fayoumi ont été contrôlées pour la

  6. 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

  7. Proprits thermiques; matriaux pour haute temprature Facult des Sciences Appliques, Dpartement ASMA, Science des Matriaux

    E-print Network

    Liège, Université de

    , Département ASMA, Science des Matériaux Jacqueline LECOMTE-BECKERS & Yann GREDAY dans le cadre du Printemps pour haute température Faculté des Sciences Appliquées, Département ASMA, Science des Matériaux

  8. DIFFUSION DES ESSAIS DE MATRISE Procdure l'usage des facults

    E-print Network

    DIFFUSION DES ESSAIS DE MAÎTRISE Procédure à l'usage des facultés de l'Université Laval (UL) ENTRÉE bonifié en ce qui concerne la diffusion des essais de maîtrise. Ce document présente la procédure à suivre pour déposer une demande de diffusion d'un essai. La diffusion d'un format électronique rend les essais

  9. 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

  10. LISTE DES SECTIONS ET DES COMMISSIONS INTERDISCIPLINAIRES DU COMIT NATIONAL DE LA RECHERCHE SCIENTIFIQUE

    E-print Network

    van Tiggelen, Bart

    LISTE DES SECTIONS ET DES COMMISSIONS INTERDISCIPLINAIRES DU COMITÉ NATIONAL DE LA RECHERCHE laboratoire au cosmos Institut national de physique nucléaire et de physique des particules (IN2P3) 2 Théories physiques : méthodes, modèles et applications Institut de physique (INP) 3 Matière condensée : structures et

  11. RECHERCHES SUR LES TEXTURES DES TATS MSOMORPHES. 6 2014 DISLOCATIONS COINS ET SIGNIFICATION DES CLOISONS

    E-print Network

    Boyer, Edmond

    DES CLOISONS DE GRANDJEAN-CANO DANS LES CHOLESTÉRIQUES (*) Y. BOULIGAND Laboratoire de Zoologie, E suivants sont des paires de disinclinaisons (03C4 -, 03BB+) dans la terminologie de Kléman et de Friedel décrochements ± p/2 le long des paires (03C4 -, 03BB+) sont de courts segments présentant une configuration

  12. Dotation et disparités régionales des performances scolaires. Le cas des collèges au Burkina Faso

    Microsoft Academic Search

    Justine Coulidiati-Kiëlem

    2008-01-01

    Cette étude a pour but d'identifier les caractéristiques des régions stables dans la performance mesurée par la réussite au BEPC, et tenant compte des ressources qui leur ont été allouées pour leur fonctionnement. La stabilité dans le temps de la performance des établissements est abordée en considérant les scores obtenus au BEPC sur un certain nombre d'années. Les résultats saillants

  13. Matrise et usage des TIC : la situation des enseignants en Belgique francophone

    E-print Network

    Paris-Sud XI, Université de

    1 Maîtrise et usage des TIC : la situation des enseignants en Belgique francophone Henry Julie discours européen concernant la maîtrise des TIC par les enseignants, les auteurs pointent du doigt les complémentaires et présentent la seule certification TIC existant à l'heure d'écrire ce texte : form@TICEF. La

  14. La valorisation boursire des tats financiers des socits franaises : pertinence du rfrentiel IFRS

    E-print Network

    Paris-Sud XI, Université de

    IFRS Denis Cormier CIFO ESG UQAM Samira Demaria Université de Nice-Sophia Antipolis - GREDEG Pascale valorisation boursière des états financiers des sociétés françaises : pertinence du référentiel IFRS Résumé du référentiel comptable français et après l'adoption des IFRS. Les résultats sont les suivants

  15. L'EVALUATION DES PERFORMANCES : UNE COMPARAISON ENTRE LES PRATIQUES DES

    E-print Network

    Boyer, Edmond

    année à des entreprises américaines par L. Maisel en partenariat avec l'AICPA (American Institute'utiliser des indicateurs financiers et non monétaires dans l'évaluation de la performance des entreprises the use of financial and non-monetary information in the measurement and the analysis of firms

  16. Difficile convergence des archives ouvertes en SIC # Difficile convergence des archives ouvertes

    E-print Network

    Paris-Sud XI, Université de

    Difficile convergence des archives ouvertes en SIC # Difficile convergence des archives ouvertes en Paris RÉSUMÉ. L'article rend compte d'un test de moissonnage pour quatre archives ouvertes sélectionnées'identification des archives ouvertes SIC sur le répertoire international OpenDOAR, est ensuite approfondie à partir

  17. MTABOLISME DE LA FLORE INTESTINALE DU PORC DGRADATION DES FORMES L ET D DES ACIDES AMINS

    E-print Network

    Paris-Sud XI, Université de

    MÉTABOLISME DE LA FLORE INTESTINALE DU PORC DÉGRADATION DES FORMES L ET D DES ACIDES AMINÉS M. C. MICHEL Simone BOCHE Laboratoire des Métabolismes Centre national de Recheyches zootechniques, 78 - Jouy-en-Josas - -- SOMMAIRE In vitro, la flore microbienne intestinale du porc catabolise tous les acides aminés. L

  18. CONTRIBUTION A LA DTERMINATION DES PARAMTRES DES RSONANCES NEUTRONIQUES DE L'URANIUM 235

    E-print Network

    Paris-Sud XI, Université de

    712. CONTRIBUTION A LA DÉTERMINATION DES PARAMÈTRES DES RÉSONANCES NEUTRONIQUES DE L'URANIUM 235, OCTOBRE 1961, La mesure de la section efficace de fission de l'uranium-235, déjà publiée, et qui avait. venin du Service de Calcul Électronique de Saclay, pondant à une température de Debye des oxydes d'uranium

  19. Minorites, capacites cognitives et revenus des Canadiens

    Microsoft Academic Search

    Ross Meng Ronald Finnie

    2003-01-01

    A partir des donnees de l'Enquete sur les capacites de lecture et d'ecriture utilisees quotidiennement (ECLEUQ) de Statistique Canada, nous avons etudie les differences de revenus entre les minorites et les Blancs et l'importance des capacites cognitives dans les modeles de revenus observes. Certains groupes de minorites ont des capacites de lecture et de calcul considerablement inferieures (d'apres les tests)

  20. NOUVEL APPAREILLAGE DE MESURE DES AIMANTATIONS ;

    E-print Network

    Paris-Sud XI, Université de

    est suivant l'axe c à basse température et dans le plan de base à des températures. supérieures à 600 0 dans laquelle 0 désigne l'angle de l'aimantation spontanée Jg avec l'axe c. La déter- mination des'angle du champ extérieur He avec l'axe c ; nous avons mesuré pour différents angles cp, dans des champs

  1. Gesundheit als Sehnsucht — Religiöse Aspekte des Gesundheitsbegriffs

    Microsoft Academic Search

    Matthias Stiehler

    2001-01-01

    Zusammenfassung  Religiöse Aspekte des Gesundheitsbegriffs spielen innerhalb der Gesundheitswis-senschaft nur eine untergeordnete Rolle, obwohl\\u000a Sinn- und Wertefragen unser Ver-stdndnis von Gesundheit bis heute beeinflussen. Diese Fragen sind dabei weniger im Alltag\\u000a als mehr in Krisensituationen verortet, die das selbstverständlich Gege-bene aufheben. Eine Analyse des biblischen Befundes\\u000a eröffnet vier Themenfür eine Ausweitung des Gesundheitsbegriffs unter religiösen Gesichtspunkten, die in dieser Arbeit begin-nend

  2. Produire des actes juridiques David Pontille*

    E-print Network

    Paris-Sud XI, Université de

    'espace, c'est qu'on l'a partagée avec des non-humains. (Latour 1994, p. 604) Incarner la force du droit Deux'ensemble des professions juridiques, des conseillers d'Etat qui ont le pouvoir de dire le droit (Latour 2002'est au moins en partie parce qu'il prend une forme palpable et transportable. B. Latour (2002, chap. 2

  3. Iatrogénie Sexuelle des Médicaments: conduite à tenir

    Microsoft Academic Search

    Stéphane Droupy

    2005-01-01

    Résumé  Une des étapes primordiale de la prise en charge des troubles sexuelles est l’identification d’une éventuelle cause médicamenteuse.\\u000a De nombreux médicaments sont en fait probablement moins impliqués eux-mêmes dans la survenue de troubles sexuels que la maladie\\u000a pour laquelle ils ont été prescrits. Ainsi, l’analyse critique de la littérature, la standardisation des paramètres mesurables\\u000a de la sexualité utilisés en études

  4. CONSEIL GENERAL DES CTES D'ARMOR

    E-print Network

    Brest, Université de

    CONSEIL GENERAL DES CÔTES D'ARMOR LUTTE PREVENTIVE ET CURATIVE CONTRE LA PROLIFERATION DES MAREES-Michel-en-Grève (Côtes d'Armor) _________ GEOMER Septembre 2003 UMR LETG - 6554 du C.N.R.S. hal-00083706,version1-12Aug2014 #12;Poche du Yar 2002-2003 ­ GEOMER-UMR 6554 CNRS -1- CONSEIL GENERAL DES COTES D'ARMOR LUTTE

  5. Sur la théorie des perturbations en mécanique quantique (I)

    Microsoft Academic Search

    M. Schönberg

    1951-01-01

    Resumé  Nous donnons des formes modifiées des développements de la théorie quantique des perturbations pour des problèmes stationnaires\\u000a ou non stationnaires. Les formes modifiées du développement stationnaire de Schrödinger sont plus simples que le développement\\u000a original. La forme modifiée du développement non stationnaire de Dirac ne contient pas des termes séculaires et elle se rattache\\u000a étroitement à une des formes modifiées

  6. Der osmotische Druck des Serumalbumins

    Microsoft Academic Search

    Wolfgang Pauli; Paul Fent

    1934-01-01

    Zusammenfassung  \\u000a \\u000a \\u000a \\u000a 1. \\u000a \\u000a Die Methode von Krogh und Nakazawa wird durch einige Abnderungen der osmotischen Zelle, der Ablesung und der Gehaltsbestimmung\\u000a der gemessenen Flssigkeit zur genaueren Bestimmung des osmotischen Druckes von Kolloiden, insbesondere von Proteinen, mit\\u000a Mengen von 0,4 ccm verwendbar gemacht.\\u000a \\u000a \\u000a \\u000a \\u000a 2. \\u000a \\u000a Es werden die bisherigen Ergebnisse der ultrazentrifugalen und der osmotischen Druckmethode bei der Bestimmung des Molekulargewichtes\\u000a isoelektrischer Proteine

  7. Treatment of coal liquids

    SciTech Connect

    Gorbaty, M.L.; Liotta, R.

    1981-03-31

    Coal liquids are rendered compatible with petroleum liquids by selective oxygen alkylation or oxygen acylation of weakly acidic protons such as phenolic and carboxylic functionalities by means of a phase transfer reaction. Phenolic and carboxylic functional substituents, which are very polar, are converted to relatively non-polar ethers and esters, respectively. The o-alkylation or oacylation is carried out in a binary liquid phase solution (Organic/water). A quaternary ammonium or phosphonium salt is reacted with alkali or alkaline earth base (Caustic) to produce the corresponding quaternary ammonium or phosphonium base (An example of a phase transfer reagent). This quaternary base is non -nucleophilic and readily removes the phenolic and carboxylic protons, but does little else to the coal liquid molecules. After the removal of the weakly acidic protons by the quaternary base, the phenoxides and carboxylates which are produced then undergo O -alkylation or o-acylation. The alkylating or acylating agent comprises a carbon-bearing functionality and a displaceable leaving group. The o-alkylation or o-acylation reduces hydrogen bonding and therefore polarity, thereby rendering coal liquids more compatible with petroleum liquids.

  8. HACK Patrice Les coulisses des assistances tlphoniques

    E-print Network

    Paris-Sud XI, Université de

    HACK Patrice 1 ________________________________________________________________ Les coulisses des Criminologie et de Police Technique et Scientifique LXV (2012) 110" #12;HACK Patrice 2 1 ­ Données et méthode

  9. Methoden zur Diagnose und zum Monitoring des Trockenen Auges: Bericht des Diagnostic Methodology Subcommittee des International Dry Eye WorkShop (2007)

    Microsoft Academic Search

    J. Bron; Mark B. Abelson; George Ousler; E. Pearce; Alan Tomlinson; Norihiko Yokoi; Janine A. Smith; Carolyn Begley; Barbara Caffery; Kelly Nichols; Debra Schaumberg; Oliver Schein; Margarita Calonge; Christophe Baudouin; Eiki Goto; Franz Grus; Jerry Paugh

    ZUSAMMENFASSUNG Das Diagnostic Methodology Subcommittee des DEWS (Dry Eye Workshop) hatte folgende Ziele: 1) Identifi kation von Tests für Screening, Diagnose und Überwachung des Trockenen Auges, 2) Etablierung von Leistungskriterien für diese Tests und 3) Betrachtung des Nutzens von Tests in einer Vielzahl klinischer Situationen. Das Komitee erstellte eine Datenbank mit Tests zur Verwendung bei der Diagnose und Überwachung des

  10. Pour une histoire mtisse des sciences du monde physique

    E-print Network

    Aubin, David

    Pour une histoire métisse des sciences du monde physique (chaos, observatoire, guerre) Document de ....................................................................................................................... 47 e) six propositions pour une histoire métisse des sciences du monde physique

  11. 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

  12. 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.

  13. 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

  14. Etude cytophotomtrique de l'ADN et des nucloprotines des spermatozodes du blier : influence du sjour

    E-print Network

    Paris-Sud XI, Université de

    Etude cytophotométrique de l'ADN et des nucléoprotéines des spermatozoïdes du bélier : influence du'un complexe entre l'ADN et la protéine spécifique du spermatozoïde (BNSP) riche en cystéine et en arginine colorabi- lité de l'ADN par le Feulgen sans que la teneur en ADN des spermatozoïdes, mesurée en UV ne

  15. 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

  16. 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.

  17. Macromolecular sensing at the liquid-liquid interface

    NASA Astrophysics Data System (ADS)

    Herzog, Grégoire; Flynn, Shane; Arrigan, Damien W. M.

    2011-08-01

    We report here the electrochemical sensing of macromolecules, such as polyLysine dendrimers, at the polarised liquid | liquid interface. Electrochemistry at the liquid | liquid interface is a powerful analytical technique which allows the detection of non-redox active molecules via ion transfer reactions at a polarised water - oil interface. We demonstrate here that different parameters of the polyLysine dendrimers (charge number, molecular weight) have a strong influence on the sensitivity and limit of detection of these macromolecules. This work will help to the development of sensors based on charge transfer at the liquid | liquid interface.

  18. Structure, stability and behaviour of nucleic acids in ionic liquids

    PubMed Central

    Tateishi-Karimata, Hisae; Sugimoto, Naoki

    2014-01-01

    Nucleic acids have become a powerful tool in nanotechnology because of their conformational polymorphism. However, lack of a medium in which nucleic acid structures exhibit long-term stability has been a bottleneck. Ionic liquids (ILs) are potential solvents in the nanotechnology field. Hydrated ILs, such as choline dihydrogen phosphate (choline dhp) and deep eutectic solvent (DES) prepared from choline chloride and urea, are ‘green’ solvents that ensure long-term stability of biomolecules. An understanding of the behaviour of nucleic acids in hydrated ILs is necessary for developing DNA materials. We here review current knowledge about the structures and stabilities of nucleic acids in choline dhp and DES. Interestingly, in choline dhp, A–T base pairs are more stable than G–C base pairs, the reverse of the situation in buffered NaCl solution. Moreover, DNA triplex formation is markedly stabilized in hydrated ILs compared with aqueous solution. In choline dhp, the stability of Hoogsteen base pairs is comparable to that of Watson–Crick base pairs. Moreover, the parallel form of the G-quadruplex is stabilized in DES compared with aqueous solution. The behaviours of various DNA molecules in ILs detailed here should be useful for designing oligonucleotides for the development of nanomaterials and nanodevices. PMID:25013178

  19. Structure, stability and behaviour of nucleic acids in ionic liquids.

    PubMed

    Tateishi-Karimata, Hisae; Sugimoto, Naoki

    2014-08-01

    Nucleic acids have become a powerful tool in nanotechnology because of their conformational polymorphism. However, lack of a medium in which nucleic acid structures exhibit long-term stability has been a bottleneck. Ionic liquids (ILs) are potential solvents in the nanotechnology field. Hydrated ILs, such as choline dihydrogen phosphate (choline dhp) and deep eutectic solvent (DES) prepared from choline chloride and urea, are 'green' solvents that ensure long-term stability of biomolecules. An understanding of the behaviour of nucleic acids in hydrated ILs is necessary for developing DNA materials. We here review current knowledge about the structures and stabilities of nucleic acids in choline dhp and DES. Interestingly, in choline dhp, A-T base pairs are more stable than G-C base pairs, the reverse of the situation in buffered NaCl solution. Moreover, DNA triplex formation is markedly stabilized in hydrated ILs compared with aqueous solution. In choline dhp, the stability of Hoogsteen base pairs is comparable to that of Watson-Crick base pairs. Moreover, the parallel form of the G-quadruplex is stabilized in DES compared with aqueous solution. The behaviours of various DNA molecules in ILs detailed here should be useful for designing oligonucleotides for the development of nanomaterials and nanodevices. PMID:25013178

  20. Analyse des possibilités de fonctionnement en régime des désexcitation des moteurs à aimants permanents

    NASA Astrophysics Data System (ADS)

    Multon, Bernard; Lucidarme, Jean; Prévond, Laurent

    1995-05-01

    In this paper, we study the extending of speed range of motors (or generators) with permanent magnet inductor and supplied by electronic converter. The amplitude of phase voltage and current waveforms are limited by electronics supply. The aim of this study is to achieve a maximum power near of the base speed one on an extended speed range. This require an airgap flux weakening so called “flux weakening” above base speed. A parametric analysis of motor electromagnetic characteristics is made to show the influence of armature reaction and magnetic saliency on speed range. We show that exists an ideal condition to obtain a constant power speed range theoretically unlimited. Magnetic saliency permits to enhance the power factor especially when L_d> L_q. As main hypotheses, we consider no saturation, e.m.f. and current sine waveforms and a sinusoidal airgap flux density. Finally, we recapitulate the permanent magnet rotor structures able to obtain a flux-weakening operation. Cet article traite de l'extension de la plage de vitesse des moteurs (ou alternateurs) à excitation par aimants permanents et alimentés par convertisseur électronique. La tension et le courant sont limités en amplitude par l'alimentation électronique.L'objectif est d'obtenir une puissance proche de celle correspondant au régime de base sur une plage de vitesse étendue. Ceci nécessite une réduction de flux d'entrefer ou “désexition” au delà de la vitesse de base. Une analyse paramétrique des caractéristiques du moteur est effectuée pour mettre en évidence l'influence de la réaction d'induit et de la saillance magnétique. Nous montrons qu'il existe une condition idéale pour obtenir une plage de fonctionnement à puissance constante théoriquement illimitée. La saillance magnétique permet d'accroître le facteur de puissance surtout lorsque L_d> L_q. Les principales hypothèses de cette étude sont l'absence de saturation, des f.e.m. et des courants sinusoïdaux et une induction spatiale sinusoïdale dans l'entrefer. Enfin, nous effectuons un bilan des structures de rotors permettant un fonctionnement en régime de désexcitation.

  1. FACULT DES LETTRES PRIX MARCEL COMPAGNON

    E-print Network

    Halazonetis, Thanos

    [Texte] FACULTÉ DES LETTRES PRIX MARCEL COMPAGNON ... des sciences de l'Antiquité : récompense un mémoire de maîtrise dans un domaine qui ne bénéficie pas d'un prix spécifique. Montant 3'000 CHF pour chaque prix Conditions particulières Obtenir au mémoire de maîtrise la note minimale de 5,5. Le mémoire

  2. LETTRES A LA RDACTION MESURE DES MOBILITS

    E-print Network

    Boyer, Edmond

    verre et graphitage externe ( fcg. 1). 1/anode ne comporte pas de soudure, le fil étant terminé par des sont obtenus par ramollissement du verre (qualité B-24 des verreries de Choisy-le-Roi) ; les extrémités'introduisent aucune perturbation [5]. Les compteurs comportent un robinet en verre B-24 et un rodage conique

  3. HPC en Calcul des Structures Piotr Breitkopf

    E-print Network

    van Tiggelen, Bart

    HPC en Calcul des Structures Piotr Breitkopf UTC, Laboratoire Roberval, UMR (des solides) a été très présente à l'origine du HPC Aujourd'hui elle est quasi-absente Avons-nous encore besoin du HPC ? (queson provocatrice) Si oui

  4. Behandlung der Knocheninfektion im Bereich des Schädels

    Microsoft Academic Search

    P. Knöringer

    1986-01-01

    Zusammenfassung  Die Osteomyelitis im Bereich des Schdels tritt vorzugsweise postoperativ, aber auch posttraumatisch sowie fortgeleitet bei Nasenebenhhleninfektionen oder selten metastatisch hmatogen auf. Die bliche Behandlung besteht in einer exakten Wundsuberung mit Fistelexzision, der Resektion des osteomyelitischen Knochens und der Entfernung allen eitrigen und devitalen Gewebes, gegebenenfalls einschlielich der Sanierung einer infizierten Nasennebenhhle. Nach Beseitigung der Infektion wird sechs bis zwlf Monate

  5. Maligne, nichtepitheliale Tumoren des Corpus uteri

    Microsoft Academic Search

    Mathias K. Fehr; Daniel Fink

    ZusammenfassungUterine Sarkome stellen eine heterogene Gruppe von Neoplasien dar, welche etwa 8% der Malignome des Uterus ausmachen. Am häufigsten sind die Karzinosarkome [früher maligne, gemischte mesenchymale Tumoren (MMMT) des Uterus], die etwa 40–50% aller Sarkome stellen. Leiomyosarkome sind am zweithäufigsten und endometriale Stromasarkome am seltensten. Ein ausgedehntes operatives Staging inklusive Lymphadenektomie ist beim Karzinosarkom indiziert. Beim Leiomyosarkom wird eine abdominale

  6. Former des enseignants avec la visioconfrence

    E-print Network

    Paris-Sud XI, Université de

    visioconférence qui réunissent des enseignants novices en formation initiale, des enseignants experts sur le (beginners and experts) in the field and lecturers. Our study is based on the analysis of the participants be an enriching training auxiliary. MOTS-CLES : visioconférence, Technologies de l'Information et de la

  7. MISE AU POINT SYMTRIE DES INTERACTIONS FORTES

    E-print Network

    Paris-Sud XI, Université de

    sujet peut etre utile meme s'il est condamn6;k parattre mal equilibre d'ici quelque temps. Le nombre des. Le fait qu'on puisse aujour- d'hui rassembler 18 baryons dans un meme multiplet, et dans un autre 17 ainsi accumul6es fait ressortir des regularites remarquables. Plusieurs particules de meme spin et meme

  8. Verbreitung und Strukturen des Tabakkonsums in Deutschland

    Microsoft Academic Search

    T. Lampert; M. Burger

    2005-01-01

    Der Tabakkonsum erhöht die Auftretenswahrscheinlichkeit vieler chronisch-degenerativer Krankheiten und verursacht erhebliche gesellschaftliche Folgekosten. Die nach wie vor starke Verbreitung des Rauchens in der Bevölkerung verdeutlicht somit einen vordringlichen gesundheitspolitischen Handlungsbedarf. Nach Daten des telefonischen Gesundheitssurveys 2003 rauchen in Deutschland rund 37% der 18-jährigen und älteren Männer und 28% der gleichaltrigen Frauen. Fast die Hälfte der täglichen Raucher und ein Drittel

  9. DPARTEMENT DES RELATIONS EXTRIEURES Service Communication

    E-print Network

    Cerf, Nicolas

    dispositifs." 1 OMS, « Chronic and noncommunicable diseases: fact sheet », http://www-ingénieurs de l'ULB ont construit, au Vietnam, des dispositifs de purification de l'air des habitats. Ces dispositifs serviront dans le cadre d'une étude clinique destinée à déterminer le lien entre la pollution

  10. Le cynisme des chiens Jacky Dahomay.

    E-print Network

    Blondel, Corinne - Institut de Mathématiques de Jussieu, Université Paris 7

    Le cynisme des chiens Jacky Dahomay. Ecrivain, membre de la Ligue des Droits de l'Homme Professeur fait par un enseignant du Gers concernant l'intrusion dans sa classe de gendarmes et d'un chien, m'établissement, ni inspecteur, ni ministre et, à fortiori, ni gendarme ni chien. Impossible ! A moins d'un cas de

  11. Thorie des Jeux Et ses Applications

    E-print Network

    Giraud, Olivier

    relance »...) Importance de la théorie des probabilités #12;Un Peu d'Histoire John von Neumann (1903-1957 si cBJohn von Neumann (1944 économique et politique Quelques contributions de J. Von Neumann : Axiomatisation des mathématiques

  12. Ateliers Informatique TAL Traitement automatique des langues

    E-print Network

    Inkpen, Diana

    Ateliers Informatique TAL Traitement automatique des langues #12;Université d'Ottawa · Faculté de génie · Informatique #12;Faculté de génie | Faculty of Engineering · Nous enseignons quatre programmes à l'Ecole die SIGE ­ Informatique (CSI): Pour les étudiants qui désirent développer des applications

  13. Habilitation Diriger des Recherches Spcialits : Mathmatiques, Informatique

    E-print Network

    Poinsot, Laurent

    Habilitation à Diriger des Recherches Spécialités : Mathématiques, Informatique Le 8 novembre 2011 6139 Gérard H. E. Duchamp Professeur des Universités, Université Paris XIII, Rapporteur Laboratoire d'Informatique Universités, Université Paris-Est Marne-la-Vallée, Examinateur Institut d'électronique et d'informatique

  14. Grosplansurl'anne desMathspourlaTerre

    E-print Network

    Dambrine, Marc

    on le souhai tera ;c'estlatechniqueCAES(compressed air energy storage). « Pour le stockage à grande leur nombre, pour des raisons géographiques. Suivant la même logique, l'eau peut être remplacée par l'air primerl'air,quipourraêtredétenduulté rieurement dans des turbines afin de restituer l'électricité quand

  15. ce des stages 821-7747 | co

    E-print Network

    Spino, Claude

    _____ Servic 819 8 Pré sur Tous couve notam vacan Au be pour ___________ ce des stages 821 et d personne formation Nos stagi mais bien pas dans Un stage vertu d'u fois leur p un progra droit d profession aires ne fon n des stage leur cas. de formatio ne loi, qui p programme amme d'étu xercer une p de

  16. 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.

  17. Viscosity of liquid anorthite.

    NASA Technical Reports Server (NTRS)

    Cukierman, M.; Uhlmann, D. R.

    1973-01-01

    The viscosity of liquid anorthite has been determined over the temperature ranges between 1450 to 1620 C and 820 to 950 C. The high-temperature data agree well with previous experimental data and with predictions of the Bottinga and Weill model. The overall log (viscosity) versus 1/T relation exhibits pronounced and rather continuous curvature. The viscosity of anorthite is higher at any given temperature and more strongly temperature-dependent than that of the anorthite-rich lunar compositions 14259, 14310, and 15418. The room-temperature density of glassy anorthite (2.64 gm/cu cm) and the thermal expansion coefficients of glassy and liquid anorthite have also been determined. The volume expansion coefficient for the glass is about 0.000018 per deg C, and that for the liquid is about 0.000048 per deg C. These values are used to relate the high-temperature flow data to the predictions of free-volume theories.

  18. 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.

  19. 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

  20. 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.

  1. Breakup of Liquid Filaments

    E-print Network

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

    2012-01-01

    in the formation of droplets from a thin water stream trickling from a tap, and in the quite different behaviour of the more viscous threads of honey or syrup flowing from a spoon [1]. The break- up of liquid jets is important in several practical con- texts... , including the dispersion of liquid drugs into res- pirable droplets, microfluidics, crop- and paint-spraying, and ink-jet printing [2–4]. There are also biological sys- tems in which either long filaments remain intact, or many droplets are formed [5, 6...

  2. Liquid Crystals: LCD Displays

    NSDL National Science Digital Library

    In this activity, by the Concord Consortium's Molecular Literacy project, students will learn the history and applications of liquid crystal technology. This interactive presentation will allow students to not only learn about the technology, but it will actually allow them to analyze and work with examples. Everything from flat panel televisions to mood rings are used to show how liquid crystal plays an integral role in many products. The activity itself is a java-based interactive resource built upon the free, open source Molecular Workbench software. In addition, visitors will find an overview of the activity, assessments, and concepts and their correlation to AAAS and NSES standards.

  3. SLD liquid argon calorimeter

    SciTech Connect

    Vella, E.

    1992-10-01

    The liquid argon calorimeter (LAC) of the SLD detector is a parallel plate -- liquid argon sampling calorimeter, used to measure particle energies in Z[sup 0] decays at the Stanford Linear Collider. The LAC module design is based on a unique projective tower structure, in which lead plates and segmented lead tiles serve both as absorbers and electrodes. The LAC front end electronics incorporates several novel features, including extensive multiplexing and optical fiber readout, which take advantage of the low SLC beam crossing frequency. The operational performance of the LAC during the recently completed SLD physics run (which recorded over 10,000 Z[sup 0] events) is discussed.

  4. SLD liquid argon calorimeter

    SciTech Connect

    Vella, E.; SLD Collaboration

    1992-10-01

    The liquid argon calorimeter (LAC) of the SLD detector is a parallel plate -- liquid argon sampling calorimeter, used to measure particle energies in Z{sup 0} decays at the Stanford Linear Collider. The LAC module design is based on a unique projective tower structure, in which lead plates and segmented lead tiles serve both as absorbers and electrodes. The LAC front end electronics incorporates several novel features, including extensive multiplexing and optical fiber readout, which take advantage of the low SLC beam crossing frequency. The operational performance of the LAC during the recently completed SLD physics run (which recorded over 10,000 Z{sup 0} events) is discussed.

  5. Mixed Stationary Liquid Phases for Gas-Liquid Chromatography.

    ERIC Educational Resources Information Center

    Koury, Albert M.; Parcher, Jon F.

    1979-01-01

    Describes a laboratory technique for use in an undergraduate instrumental analysis course that, using the interpretation of window diagrams, prepares a mixed liquid phase column for gas-liquid chromatography. A detailed procedure is provided. (BT)

  6. 138. LIQUID NITROGEN INSTRUMENT PANEL ON EAST WALL OF LIQUID ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    138. LIQUID NITROGEN INSTRUMENT PANEL ON EAST WALL OF LIQUID NITROGEN CONTROL ROOM (115), LSB (BLDG. 770) - Vandenberg Air Force Base, Space Launch Complex 3, Launch Pad 3 West, Napa & Alden Roads, Lompoc, Santa Barbara County, CA

  7. L'valuation du prix des actions par les fondamentaux

    E-print Network

    Paris-Sud XI, Université de

    L'évaluation du prix des actions par les fondamentaux : analyse du marché français Dominique Pépin(*) Depuis 1920, le prix des actions en France, comme partout dans le monde, a connu d'importantes variations des banques centrales, et à se demander si ces dernières ne devaient pas prendre en compte le prix des

  8. Les disparits binoculaires des verres unifocaux Cline Devismea,b

    E-print Network

    Paris-Sud XI, Université de

    Les disparités binoculaires des verres unifocaux Céline Devismea,b , Björn Drobeb , Guillaume'apposition de verres ophtalmiques devant les yeux va engendrer une modification de la distribution des'analyse descriptive des disparités binoculaires, horizontales et verticales, produites par des verres ophtalmiques

  9. Journes Filtration des Arosols NANCY 7 & 8 juin 2007

    E-print Network

    Paris-Sud XI, Université de

    1ères Journées Filtration des Aérosols NANCY ­ 7 & 8 juin 2007 C11 / 1 FILTRATION DES rebond thermique. Mots Clés : Filtration, Nanoparticules, Rebond Thermique. INTRODUCTION Le développement spectaculaire des nanotechnologies ces dernières années a rendu la question de la filtration des

  10. GE.07-51666 (F) 240907 280907 des Nations Unies

    E-print Network

    Muðan, Uðurhan

    relatives à l'application des normes internationales d'information financière (IFRS) en vue d'élaborer des (IFRS). Dans la présente étude de cas, les questions pratiques relatives au cadre réglementaire, au'application des IFRS. La présente étude de cas a pour principal objectif de tirer des enseignements de l

  11. Changement de normes : la stabilit des choix comptables Samira DEMARIA

    E-print Network

    Boyer, Edmond

    comptables effectués par les groupes français lors de la première adoption des normes comptables IAS/IFRS questionnaire en ligne et des entretiens semi-directifs auprès des responsables de la migration vers les IFRS au normatif. Mots clés : normes IAS/IFRS, transition, choix d'options comptables, théorie des conventions

  12. TabledesMatiresServicesuniversitairesetservices Table des Matires Services

    E-print Network

    . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 180 · Zone de Central Square . . . . . . . . . . . . . . . . . . . . . . . . . 181 · Sports et loisirs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 181 · Installations sportives . . . . . . . . . . . . . . . . . . . . . . . . . . . 182 · Bureau des

  13. iovi* ^MAA-L ft} DES PONTS ET CHAUSSEES

    E-print Network

    Paris-Sud XI, Université de

    'Ecole Nationale Supérieure des Travaux Publics - Yamoussoukro" (ENSTP) du 3è r a e Projet de Développement Urbain motivation et de persévérance. J'exprime toute ma gratitude à M. Michel SAVY, Professeur à Ï'ENPC et des collègues et des personnes travaillant sur des questions similaires dans l'administration et dans

  14. RECHERCHES EXPRIMENTALES SUR LA DURE DE PASSAGE DES SPERMATOZODES

    E-print Network

    Boyer, Edmond

    pertes d'ADN au cours des extractions : - variations dans la teneur en ADN en fonction du nombre des lavages avec la solution de KREI3S-lIENSELEIT-RINGER, - variations dans la teneur en ADN des autres : - contamination par le plasma séminal des phospholipides,- contamination de l'ADN. 2. Dosage du

  15. Separation of Liquid Solutions by Contained Liquid Membranes

    Microsoft Academic Search

    A. Sengupta; R. Basu; R. Prasad; K. K. Sirkar

    1988-01-01

    The technique of contained liquid membranes (CLM) for liquid solution separation is discussed. The CLM is obtained by confining the membrane liquid between two sets of microporous hollow fibers (MHF). The lumen of the hollow fiber carries the feed or the strip solution under proper phase pressure condition vis-a-vis the membrane phase. Various possible structural configurations of the CLM are

  16. Polymorphism in glassy silicon: Inherited from liquid-liquid phase transition in supercooled liquid

    NASA Astrophysics Data System (ADS)

    Zhang, Shiliang; Wang, Li-Min; Zhang, Xinyu; Qi, Li; Zhang, Suhong; Ma, Mingzhen; Liu, Riping

    2015-02-01

    Combining molecular dynamics (MD) simulation and Voronoi polyhedral analyses, we discussed the microstructure evolution in liquid and glassy silicon during cooling by focusing on the fraction of various clusters. Liquid-liquid phase transition (LLPT) is detected in supercooled liquid silicon However, freezing the high-density liquid (HDL) to the glassy state is not achieved as the quenching rate goes up to 1014 K/s. The polyamorphism in glassy silicon is found to be mainly associated with low-density liquid (LDL).

  17. Liquid Cooled Garments

    NASA Technical Reports Server (NTRS)

    1979-01-01

    Astronauts working on the surface of the moon had to wear liquid-cooled garments under their space suits as protection from lunar temperatures which sometimes reach 250 degrees Fahrenheit. In community service projects conducted by NASA's Ames Research Center, the technology developed for astronaut needs has been adapted to portable cooling systems which will permit two youngsters to lead more normal lives.

  18. Transport in Luttinger Liquids

    NASA Astrophysics Data System (ADS)

    Rao, Sumathi

    We give a brief introduction to Luttinger liquids and to the phenomena of electronic transport or conductance in quantum wires. We explain why the subject of transport in Luttinger liquids is relevant and fascinating and review some important results on tunneling through barriers in a one-dimensional quantum wire and the phenomena of persistent currents in mesoscopic rings. We give a brief description of our own work on transport through doubly-crossed Luttinger liquids and transport in the Schulz-Shastry exactly solvable Luttinger-like model. With a view to making this article accessible to researchers in diverse fields such as nuclear physics, particle physics, formal field theory and condensed matter physics, we begin by first giving a brief introduction. In Sec. 1, we explain the words such as "Luttinger liquid" and "transport" in the title. We also motivate the study of this subject by showing that field is very important at the current time from the applications point of view and describe why it is theoretically fascinating. We then give a quick review of some of the important results in the field in Sec. 2, before we go on to describe some work that we have recently done and are doing in this field in Sec. 3. Finally, in Sec. 4, we conclude by re-emphasizing the importance of this area and drawing attention towards future possibilities.

  19. Liquid metal thermoacoustic engine

    Microsoft Academic Search

    G. W. Swift; A. Migliori; J. C. Wheatley

    1986-01-01

    We are studying a liquid metal thermoacoustic engine both theoretically and experimentally. This type of engine promises to produce large quantities of electrical energy from heat at modest efficiency with no moving parts. A sound wave is usually thought of as consisting of pressure oscillations, but always attendant to the pressure oscillation are temperature oscillations. The combination produces a rich

  20. Liquid Rocket Engine Testing

    NASA Technical Reports Server (NTRS)

    Rahman, Shamim

    2005-01-01

    Comprehensive Liquid Rocket Engine testing is essential to risk reduction for Space Flight. Test capability represents significant national investments in expertise and infrastructure. Historical experience underpins current test capabilities. Test facilities continually seek proactive alignment with national space development goals and objectives including government and commercial sectors.