Sample records for c-c bond-forming reaction

  1. Pd/C-mediated dual C-C bond forming reaction in water: synthesis of 2,4-dialkynylquinoline

    Energy Technology Data Exchange (ETDEWEB)

    Reddy, Ellanki A.; Islam, Aminul; Venu, Bolla K. [Dr. Reddy' s Laboratories Limited, Hyderabad, Andhra Pradesh (India); Mukkanti, K. [JNT University, Hyderabad, Andhra Pradesh (India). Inst. of Science and Technology. Chemistry Division; Pal, Manojit, E-mail: [Matrix Laboratories Ltd., Medak District, Andra Pradesh (India). New Drug Discovery. R and D Center


    Pd/C facilitated dual C-C bond forming reaction between 2,4-diiodoquinoline and terminal alkynes in water providing a practical and one-step synthesis of 2,4-dialkynylquinolines. A number of related quinoline derivatives were prepared in good to excellent yields using this water-based methodology. The use of other palladium catalysts and solvents was examined and the mechanism of the reaction has been discussed. (author)

  2. In Pursuit of an Ideal C-C Bond-Forming Reaction (United States)

    RajanBabu, T. V.


    Attempts to introduce the highly versatile vinyl group into other organic molecules in a chemo-, regio- and stereoselective fashion via catalytic activation of ethylene provided challenging opportunities to explore new ligand and salt effects in homogeneous catalysis. This review provides a personal account of the development of enantioselective reactions involving ethylene. PMID:19606231

  3. Bite angle effects of diphosphines in C-C and C-X bond forming cross coupling reactions

    NARCIS (Netherlands)

    Birkholz, M.N.; Freixa, Z.; van Leeuwen, P.W.N.M.


    Catalytic reactions of C-C and C-X bond formation are discussed in this critical review with particular emphasis on cross coupling reactions catalyzed by palladium and wide bite angle bidentate diphosphine ligands. Especially those studies have been collected that allow comparison of the ligand bite

  4. Pd-catalyzed autotandem C-C/C-C bond-forming reactions with tosylhydrazones: synthesis of spirocycles with extended π-conjugation. (United States)

    Barroso, Raquel; Valencia, Rocío A; Cabal, María-Paz; Valdés, Carlos


    A new Pd-catalyzed autotandem process is presented by the reaction of tosylhydrazones of cyclic ketones and 2,2'-dibromobiphenyls and related systems. The process involves cross-coupling with tosylhydrazone followed by an intramolecular Heck reaction and gives rise to spirocyclic structures. Noteworthy, two C-CAr bonds are formed on the hydrazonic carbon during the process. Depending on the starting dibromide, an array of spirofluorenes, spirodibenzofluorenes, spiroacridines, and spiroanthracenes have been prepared. Thus, this methodology may be applied for the preparation of interesting structures useful in the development of optoelectronic materials.

  5. Chiral Pd aqua complex-catalyzed asymmetric C-C bond-forming reactions: a Brønsted acid-base cooperative system. (United States)

    Sodeoka, Mikiko; Hamashima, Yoshitaka


    Chiral cationic Pd aqua complexes can function as acid-base catalysts, effectively activating active methylene and methine compounds to give chiral Pd enolates. It is noteworthy that such enolate formation occurs with concomitant formation of a strong protic acid. Although the reactivity of the Pd enolate itself is not sufficient for reactions with carbon-based electrophiles, its cooperative action with the protic acid to activate the electrophiles allows the desired C-C bond-forming reactions to proceed smoothly in a highly enantioselective manner. Based on this mechanistic feature, reactions with acetals have been developed; these are difficult to achieve using conventional basic enolate chemistry.

  6. Palladium complexes containing diphosphine and sulfonated phosphine ligands for c-c bond forming reactions. catalytic and mechanistic studies


    García Suárez, Eduardo José


    El uso de compuestos de paladio(II) para catalizar reacciones de copolimerización de monóxido de carbono y olefinas así como otros tipos de reacciones de formación de enlaces C-C muestra un creciente interés, prueba de ello es el importante numero de publicaciones realizadas en estos últimos años.En catálisis una de las mayores causas de baja productividad es la degradación del catalizador a especies menos activas. Por este motivo se dedican constantemente esfuerzos al diseño de ligandos capa...

  7. In Pursuit of an Ideal C-C Bond-Forming Reaction: Development and Applications of the Hydrovinylation of Olefins. (United States)

    Rajanbabu, T V


    Attempts to introduce the highly versatile vinyl group into other organic molecules in a chemo-, regio- and stereoselective fashion via catalytic activation of ethylene provided challenging opportunities to explore new ligand and salt effects in homogeneous catalysis. This review provides a personal account of the development of enantioselective reactions involving ethylene.

  8. General and Efficient C-C Bond Forming Photoredox Catalysis with Semiconductor Quantum Dots. (United States)

    Caputo, Jill A; Frenette, Leah C; Zhao, Norman; Sowers, Kelly L; Krauss, Todd D; Weix, Daniel J


    Photoredox catalysis has become an essential tool in organic synthesis because it enables new routes to important molecules. However, the best available molecular catalysts suffer from high catalyst loadings and rely on precious metals. Here we show that colloidal nanocrystal quantum dots (QDs) can serve as efficient and robust, precious-metal free, photoassisted redox catalysts. A single-sized CdSe quantum dot (3.0 ± 0.2 nm) can replace several different dye catalysts needed for five different photoredox reactions (β-alkylation, β-aminoalkylation, dehalogenation, amine arylation, and decarboxylative radical formation). Even without optimization of the QDs or the reaction conditions, efficiencies rivaling those of the best available metal dyes were obtained.

  9. An iron-catalysed C-C bond-forming spirocyclization cascade providing sustainable access to new 3D heterocyclic frameworks (United States)

    Adams, Kirsty; Ball, Anthony K.; Birkett, James; Brown, Lee; Chappell, Ben; Gill, Duncan M.; Lo, P. K. Tony; Patmore, Nathan J.; Rice, Craig. R.; Ryan, James; Raubo, Piotr; Sweeney, Joseph B.


    Heterocyclic architectures offer powerful creative possibilities to a range of chemistry end-users. This is particularly true of heterocycles containing a high proportion of sp3-carbon atoms, which confer precise spatial definition upon chemical probes, drug substances, chiral monomers and the like. Nonetheless, simple catalytic routes to new heterocyclic cores are infrequently reported, and methods making use of biomass-accessible starting materials are also rare. Here, we demonstrate a new method allowing rapid entry to spirocyclic bis-heterocycles, in which inexpensive iron(III) catalysts mediate a highly stereoselective C-C bond-forming cyclization cascade reaction using (2-halo)aryl ethers and amines constructed using feedstock chemicals readily available from plant sources. Fe(acac)3 mediates the deiodinative cyclization of (2-halo)aryloxy furfuranyl ethers, followed by capture of the intermediate metal species by Grignard reagents, to deliver spirocycles containing two asymmetric centres. The reactions offer potential entry to key structural motifs present in bioactive natural products.

  10. Mutability-landscape guided enzyme engineering : Improving the promiscuous C-C bond-forming activities of 4-oxalocrotonate tautomerase

    NARCIS (Netherlands)

    van der Meer, Jan Ytzen


    Enzymes do not only play a crucial role in nature, they are also increasingly used as biocatalysts for the production of complex molecules such as pharmaceuticals. However, some of the reactions that are widely used in organic synthesis have not been observed in biological systems. Hence, there is n

  11. Innovative Catalysis in Organic Synthesis Oxidation, Hydrogenation, and C-X Bond Forming Reactions

    CERN Document Server

    Andersson, Pher G


    Authored by a European team of leaders in the field, this book compiles innovative approaches for C-X bond forming processes frequently applied in organic synthesis. It covers all key types of catalysis, including homogeneous, heterogeneous, and organocatalysis, as well as mechanistic and computational studies. Special attention is focused on the improvement of efficiency and sustainability of important catalytic processes, such as selective oxidations, hydrogenation and cross-coupling reactions.The result is a valuable resource for both advanced researchers in academia and industry, as well a

  12. Acid-base bifunctional catalysis of silica-alumina-supported organic amines for carbon-carbon bond-forming reactions. (United States)

    Motokura, Ken; Tomita, Mitsuru; Tada, Mizuki; Iwasawa, Yasuhiro


    Acid-base bifunctional heterogeneous catalysts were prepared by the reaction of an acidic silica-alumina (SA) surface with silane-coupling reagents possessing amino functional groups. The obtained SA-supported amines (SA-NR2) were characterized by solid-state 13C and 29Si NMR spectroscopy, FT-IR spectroscopy, and elemental analysis. The solid-state NMR spectra revealed that the amines were immobilized by acid-base interactions at the SA surface. The interactions between the surface acidic sites and the immobilized basic amines were weaker than the interactions between the SA and free amines. The catalytic performances of the SA-NR2 catalysts for various carbon-carbon bond-forming reactions, such as cyano-ethoxycarbonylation, the Michael reaction, and the nitro-aldol reaction, were investigated and compared with those of homogeneous and other heterogeneous catalysts. The SA-NR2 catalysts showed much higher catalytic activities for the carbon-carbon bond-forming reactions than heterogeneous amine catalysts using other supports, such as SiO2 and Al2O3. On the other hand, homogeneous amines hardly promoted these reactions under similar reaction conditions, and the catalytic behavior of SA-NR2 was also different from that of MgO, which was employed as a typical heterogeneous base. An acid-base dual-activation mechanism for the carbon-carbon bond-forming reactions is proposed.

  13. Method for producing bio-fuel that integrates heat from carbon-carbon bond-forming reactions to drive biomass gasification reactions (United States)

    Cortright, Randy D.; Dumesic, James A.


    A low-temperature catalytic process for converting biomass (preferably glycerol recovered from the fabrication of bio-diesel) to synthesis gas (i.e., H.sub.2/CO gas mixture) in an endothermic gasification reaction is described. The synthesis gas is used in exothermic carbon-carbon bond-forming reactions, such as Fischer-Tropsch, methanol, or dimethylether syntheses. The heat from the exothermic carbon-carbon bond-forming reaction is integrated with the endothermic gasification reaction, thus providing an energy-efficient route for producing fuels and chemicals from renewable biomass resources.

  14. Method for producing bio-fuel that integrates heat from carbon-carbon bond-forming reactions to drive biomass gasification reactions (United States)

    Cortright, Randy D [Madison, WI; Dumesic, James A [Verona, WI


    A low-temperature catalytic process for converting biomass (preferably glycerol recovered from the fabrication of bio-diesel) to synthesis gas (i.e., H.sub.2/CO gas mixture) in an endothermic gasification reaction is described. The synthesis gas is used in exothermic carbon-carbon bond-forming reactions, such as Fischer-Tropsch, methanol, or dimethylether syntheses. The heat from the exothermic carbon-carbon bond-forming reaction is integrated with the endothermic gasification reaction, thus providing an energy-efficient route for producing fuels and chemicals from renewable biomass resources.

  15. Alkali metal mediated C-C bond coupling reaction. (United States)

    Tachikawa, Hiroto


    Metal catalyzed carbon-carbon (C-C) bond formation is one of the important reactions in pharmacy and in organic chemistry. In the present study, the electron and hole capture dynamics of a lithium-benzene sandwich complex, expressed by Li(Bz)2, have been investigated by means of direct ab-initio molecular dynamics method. Following the electron capture of Li(Bz)2, the structure of [Li(Bz)2](-) was drastically changed: Bz-Bz parallel form was rapidly fluctuated as a function of time, and a new C-C single bond was formed in the C1-C1' position of Bz-Bz interaction system. In the hole capture, the intermolecular vibration between Bz-Bz rings was only enhanced. The mechanism of C-C bond formation in the electron capture was discussed on the basis of theoretical results.

  16. Design and Synthesis of Chiral Zn2+ Complexes Mimicking Natural Aldolases for Catalytic C–C Bond Forming Reactions in Aqueous Solution

    Directory of Open Access Journals (Sweden)

    Susumu Itoh


    Full Text Available Extending carbon frameworks via a series of C–C bond forming reactions is essential for the synthesis of natural products, pharmaceutically active compounds, active agrochemical ingredients, and a variety of functional materials. The application of stereoselective C–C bond forming reactions to the one-pot synthesis of biorelevant compounds is now emerging as a challenging and powerful strategy for improving the efficiency of a chemical reaction, in which some of the reactants are subjected to successive chemical reactions in just one reactor. However, organic reactions are generally conducted in organic solvents, as many organic molecules, reagents, and intermediates are not stable or soluble in water. In contrast, enzymatic reactions in living systems proceed in aqueous solvents, as most of enzymes generally function only within a narrow range of temperature and pH and are not so stable in less polar organic environments, which makes it difficult to conduct chemoenzymatic reactions in organic solvents. In this review, we describe the design and synthesis of chiral metal complexes with Zn2+ ions as a catalytic factor that mimic aldolases in stereoselective C–C bond forming reactions, especially for enantioselective aldol reactions. Their application to chemoenzymatic reactions in aqueous solution is also presented.

  17. Efficient C-O and C-N bond forming cross-coupling reactions catalyzed by core-shell structured Cu/Cu2O nanowires

    KAUST Repository

    Elshewy, Ahmed M.


    Oxygen and Nitrogen containing compounds are of utmost importance due to their interesting and diverse biological activities. The construction of the C-O and C–N bonds is of significance as it opens avenues for the introduction of ether and amine linkages in organic molecules. Despite significant advancements in this field, the construction of C-O and C–N bonds is still a major challenge for organic chemists, due to the involvement of harsh reaction conditions or the use of expensive catalysts or ligands in many cases. Thus, it is a challenge to develop alternative, milder, cheaper and more reproducible methodologies for the construction of these types of bonds. Herein, we introduce a new efficient ligand free catalytic system for C-O and C-N bond formation reactions.

  18. Transition-metal-catalyzed C-N bond forming reactions using organic azides as the nitrogen source: a journey for the mild and versatile C-H amination. (United States)

    Shin, Kwangmin; Kim, Hyunwoo; Chang, Sukbok


    Owing to the prevalence of nitrogen-containing compounds in functional materials, natural products and important pharmaceutical agents, chemists have actively searched for the development of efficient and selective methodologies allowing for the facile construction of carbon-nitrogen bonds. While metal-catalyzed C-N cross-coupling reactions have been established as one of the most general protocols for C-N bond formation, these methods require starting materials equipped with functional groups such as (hetero)aryl halides or their equivalents, thus generating stoichiometric amounts of halide salts as byproducts. To address this aspect, a transition-metal-catalyzed direct C-H amination approach has emerged as a step- and atom-economical alternative to the conventional C-N cross-coupling reactions. However, despite the significant recent advances in metal-mediated direct C-H amination reactions, most available procedures need harsh conditions requiring stoichiometric external oxidants. In this context, we were curious to see whether a transition-metal-catalyzed mild C-H amination protocol could be achieved using organic azides as the amino source. We envisaged that a dual role of organic azides as an environmentally benign amino source and also as an internal oxidant via N-N2 bond cleavage would be key to develop efficient C-H amination reactions employing azides. An additional advantage of this approach was anticipated: that a sole byproduct is molecular nitrogen (N2) under the perspective catalytic conditions. This Account mainly describes our research efforts on the development of rhodium- and iridium-catalyzed direct C-H amination reactions with organic azides. Under our initially optimized Rh(III)-catalyzed amination conditions, not only sulfonyl azides but also aryl- and alkyl azides could be utilized as facile amino sources in reaction with various types of C(sp(2))-H bonds bearing such directing groups as pyridine, amide, or ketoxime. More recently, a new

  19. Observation of Spontaneous C=C Bond Breaking in the Reaction between Atomic Boron and Ethylene in Solid Neon. (United States)

    Jian, Jiwen; Lin, Hailu; Luo, Mingbiao; Chen, Mohua; Zhou, Mingfei


    A ground-state boron atom inserts into the C=C bond of ethylene to spontaneously form the allene-like compound H2 CBCH2 on annealing in solid neon. This compound can further isomerize to the propyne-like HCBCH3 isomer under UV light excitation. The observation of this unique spontaneous C=C bond insertion reaction is consistent with theoretical predictions that the reaction is thermodynamically exothermic and kinetically facile. This work demonstrates that the stronger C=C bond, rather than the less inert C-H bond, can be broken to form organoboron species from the reaction of a boron atom with ethylene even at cryogenic temperatures.

  20. Chiral BINOL-derived phosphoric acids: privileged Brønsted acid organocatalysts for C-C bond formation reactions. (United States)

    Zamfir, Alexandru; Schenker, Sebastian; Freund, Matthias; Tsogoeva, Svetlana B


    BINOL-derived phosphoric acids have emerged during the last five years as powerful chiral Brønsted acid catalysts in many enantioselective processes. The most successful transformations carried out with chiral BINOL phosphates include C-C bond formation reactions. The recent advances have been reviewed in this article with a focus being placed on hydrocyanations, aldol-type, Mannich, Friedel-Crafts, aza-ene-type, Diels-Alder, as well as cascade and multi-component reactions.

  1. Reactions of the alkoxy radicals formed following OH-addition to alpha-pinene and beta-pinene. C-C bond scission reactions. (United States)

    Dibble, T S


    The atmospheric degradation pathways of the atmospherically important terpenes alpha-pinene and beta-pinene are studied using density functional theory. We employ the correlation functional of Lee, Yang, and Parr and the three-parameter HF exchange functional of Becke (B3LYP) together with the 6-31G(d) basis set. The C-C bond scission reactions of the beta-hydroxyalkoxy radicals that are formed after OH addition to alpha-pinene and beta-pinene are investigated. Both of the alkoxy radicals formed from the alpha-pinene-OH adduct possess a single favored C-C scission pathway with an extremely low barrier (approximately 3 kcal/mol) leading to the formation of pinonaldehyde. Neither of these pathways produces formaldehyde, and preliminary computational results offer some support for suggestions that 1,5 or 1,6 H-shift (isomerization) reactions of alkoxy radicals contribute to formaldehyde production. In the case of the alkoxy radical formed following OH addition to the methylene group of beta-pinene, there exists two C-C scission reactions with nearly identical barrier heights (approximately 7.5 kcal/mol); one leads to known products (nopinone and formaldehyde) but the ultimate products of the competing reaction are unknown. The single C-C scission pathway of the other alkoxy radical from beta-pinene possesses a very low (approximately 4 kcal/mol) barrier. The kinetically favored C-C scission reactions of all four alkoxy radicals appear to be far faster than expected rates of reaction with O2. The rearrangement of the alpha-pinene-OH adduct, a key step in the proposed mechanism of formation of acetone from alpha-pinene, is determined to possess a barrier of 11.6 kcal/mol. This value is consistent with another computational result and is broadly consistent with the modest acetone yields observed in product yield studies.

  2. Cathodic Aromatic C,C Cross-Coupling Reaction via Single Electron Transfer Pathway. (United States)

    Qu, Yang; Tateno, Hiroyuki; Matsumura, Yoshimasa; Kashiwagi, Tsuneo; Atobe, Mahito


    We have successfully developed a novel cathodic cross-coupling reaction of aryl halides with arenes. Utilization of the cathodic single electron transfer (SET) mechanism for activation of aryl halides enables the cross-coupling reaction to proceed without the need for any transition metal catalysts or single electron donors in a mild condition. The SET from a cathode to an aryl halide initiates a radical chain by giving an anion radical of the aryl halide. The following propagation cycle also consists entirely of anion radical intermediates.

  3. Cathodic Aromatic C,C Cross-Coupling Reaction via Single Electron Transfer Pathway

    Directory of Open Access Journals (Sweden)

    Yang Qu


    Full Text Available We have successfully developed a novel cathodic cross-coupling reaction of aryl halides with arenes. Utilization of the cathodic single electron transfer (SET mechanism for activation of aryl halides enables the cross-coupling reaction to proceed without the need for any transition metal catalysts or single electron donors in a mild condition. The SET from a cathode to an aryl halide initiates a radical chain by giving an anion radical of the aryl halide. The following propagation cycle also consists entirely of anion radical intermediates.

  4. A sensitivity study of the neutral-neutral reactions C + C3 and C + C5 in cold dense interstellar clouds

    CERN Document Server

    Wakelam, Valentine; Herbst, Eric; Talbi, Dahbia; Quan, Dongui; Caralp, Françoise


    Chemical networks used for models of interstellar clouds contain many reactions, some of them with poorly determined rate coefficients and/or products. In this work, we report a method for improving the predictions of molecular abundances using sensitivity methods and ab initio calculations. Based on the chemical network osu.2003, we used two different sensitivity methods to determine the most important reactions as a function of time for models of dense cold clouds. Of these reactions, we concentrated on those between C and C3 and between C and C5, both for their effect on specific important species such as CO and for their general effect on large numbers of species. We then used ab initio and kinetic methods to determine an improved rate coefficient for the former reaction and a new set of products, plus a slightly changed rate coefficient for the latter. Putting our new results in a pseudo-time-dependent model of cold dense clouds, we found that the abundances of many species are altered at early times, ba...

  5. The nature of solid-state N-H triplebondO/O-H triplebond N tautomeric competition in resonant systems. Intramolecular proton transfer in low-barrier hydrogen bonds formed by the triplebond O=C-C=N-NH triple bond --> <-- triplebond HO-C=C-N=N triplebond Ketohydrazone-Azoenol system. A variable-temperature X-ray crystallographic and DFT computational study. (United States)

    Gilli, Paola; Bertolasi, Valerio; Pretto, Loretta; Lycka, Antonín; Gilli, Gastone


    The tautomeric.O=C-C=N-NH triplebond --> competition in these compounds is studied here through variable-temperature (100, 150, 200, and 295 K) crystal-structure determination of pF = 1-(4-F-phenylazo)2-naphthol and oF = 1-(2-F-phenylazo)2-naphthol, two molecules that, on the ground of previous studies (Gilli, P; Bertolasi, V.; Ferretti, V.; Gilli, G. J. Am. Chem. Soc. 2000, 122, 10405), were expected to represent an almost perfect balance of the two tautomers. According to predictions, the two molecules form remarkably strong bonds (d(N triplebond O) = 2.53-2.55 A) of double-minimum or LBHB type with dynamic N-H triplebond O/ O-H triplebond N exchange in the solid state. The enthalpy differences between the two minima, as measured by van't Hoff methods from the X-ray-determined proton populations, are very small and amount to DeltaH degrees = -0.120 and DeltaH degrees = -0.156 kcal mol(-)(1) in favor of the N-H triplebond O form for pF and oF, respectively. Successive emulation of pF by DFT methods at the B3LYP/6-31+G(d,p)//B3LYP/6-31+G(d,p) level has shown that both energetic and geometric experimental aspects can be almost perfectly reproduced. Generalization of these results was sought by performing DFT calculations at the same level of theory along the complete proton-transfer (PT) pathway for five test molecules designed in such a way that the RAHB formed changes smoothly from weak N-H triplebond O to strong O-H.N through very strong N-H triplebond O/O-H triplebond N bond of LBHB type. A systematic correlation analysis of H-bond energies, H-bond and pi-conjugated fragment geometries, and H-bond Bader's AIM topological properties performed along the PT-pathways leads to the following conclusions: (a) any X-H triplebond Y H-bonded system is fully characterized by its intrinsic PT-barrier, that is, the symmetric barrier occurring when the proton affinities of X and Y are identical; (b) the intrinsic X-H triplebond Y bond associated with the symmetric barrier is

  6. Extended reaction scope of thiamine diphosphate dependent cyclohexane-1,2-dione hydrolase: from C-C bond cleavage to C-C bond ligation. (United States)

    Loschonsky, Sabrina; Wacker, Tobias; Waltzer, Simon; Giovannini, Pier Paolo; McLeish, Michael J; Andrade, Susana L A; Müller, Michael


    ThDP-dependent cyclohexane-1,2-dione hydrolase (CDH) catalyzes the CC bond cleavage of cyclohexane-1,2-dione to 6-oxohexanoate, and the asymmetric benzoin condensation between benzaldehyde and pyruvate. One of the two reactivities of CDH was selectively knocked down by mutation experiments. CDH-H28A is much less able to catalyze the CC bond formation, while the ability for CC bond cleavage is still intact. The double variant CDH-H28A/N484A shows the opposite behavior and catalyzes the addition of pyruvate to cyclohexane-1,2-dione, resulting in the formation of a tertiary alcohol. Several acyloins of tertiary alcohols are formed with 54-94 % enantiomeric excess. In addition to pyruvate, methyl pyruvate and butane-2,3-dione are alternative donor substrates for CC bond formation. Thus, the very rare aldehyde-ketone cross-benzoin reaction has been solved by design of an enzyme variant.

  7. Hairy carbon nanotube@nano-Pd heterostructures: design, characterization, and application in Suzuki C-C coupling reaction. (United States)

    Mahouche Chergui, Samia; Ledebt, Alexandre; Mammeri, Fayna; Herbst, Frédéric; Carbonnier, Benjamin; Ben Romdhane, Hatem; Delamar, Michel; Chehimi, Mohamed M


    Poly(glycidyl methacrylate), PGMA, was prepared via ATRP in bulk solution, and its epoxy groups were further acid-hydrolyzed in order to obtain a polymer with glycerol moieties (noted POH). The POH chain end C-Br bonds were subjected to a nucleophilic attack by NaN(3), resulting in azide-terminated POH (POH-N(3)). The CNTs were modified by in-situ-generated alkynylated diazonium cations from the para-alkynylated aniline of the formulas H(2)N-C(6)H(4)-C≡C-H, yielding CNT-C(6)H(4)-C≡C-H nanotubes. The azide-functionalized polymer POH-N(3) was clicked to the alkynyl-modified CNTs giving CNT@POH hybrids, which were further subjected to an oxidation resulting in carboxylated polymer-modified CNTs (noted CNT@PCOOH). The as-designed hairy CNTs served as efficient platforms for the in-situ synthesis and massive loading of 3 nm sized palladium nanoparticles (NPs). The CNT@PCOOH@Pd heterostructures prepared so far exhibited an efficient catalytic effect in the C-C Suzuki coupling reaction and were regenerated up to four times without any significant loss of catalytic activity.

  8. Asymmetric carbon-carbon bond forming reactions catalyzed by chiral titanium complexes. Efficient synthesis of optically active secondary alcohols; Kiraru na chitan shokubai ni yoru fuseitanso-tanso ketsugo keisei. Kogaku kassei dainikyu arukoru no gosei

    Energy Technology Data Exchange (ETDEWEB)

    Hayashi, M. [Yamaguchi Univ., Yamaguchi (Japan). Faculty of Science


    For asymmetric metal complex catalysts with high catalytic activity and ability for recognizing asymmetry, it is most important to choose center metals and design asymmetric organic ligands. When the authors began to study on the title reactions, combination of titanium alkoxides as center metals and chiral Schiff bases as organic ligands was unknown, although two moieties had been used independently for asymmetric reactions with excellent results. Asymmetric silylcyanation of aldehydes and enantio-selective addition of diketone to aldehydes are introduced, that have been achieved by authors using titanium complexes of the above combination. In the silylcyanation, reactivity is remarkably improved, compared with a single catalyst of titanium isopropoxide. Cyanohydrin of R from was obtained preferentially with salicyladehyde, particularly having 3-tert butyl group, in an asymmetric yield of 85 % ee. In the latter addition reaction, 5-hydroxy-3-ketoesters were obtained from benzaldehyde in an asymmetric yield as high as 91 % ee. 9 refs., 2 figs.

  9. Roles of Fe-Nx and Fe-Fe3C@C Species in Fe-N/C Electrocatalysts for Oxygen Reduction Reaction. (United States)

    Kim, Jae Hyung; Sa, Young Jin; Jeong, Hu Young; Joo, Sang Hoon


    Iron and nitrogen codoped carbons (Fe-N/C) have emerged as promising nonprecious metal catalysts for the oxygen reduction reaction (ORR). While Fe-Nx sites have been widely considered as active species for Fe-N/C catalysts, very recently, iron and/or iron carbide encased with carbon shells (Fe-Fe3C@C) has been suggested as a new active site for the ORR. However, most of synthetic routes to Fe-N/C catalysts involve high-temperature pyrolysis, which unavoidably yield both Fe-Nx and Fe-Fe3C@C species, hampering the identification of exclusive role of each species. Herein, in order to establish the respective roles of Fe-Nx and Fe-Fe3C@C sites we rationally designed model catalysts via the phase conversion reactions of Fe3O4 nanoparticles supported on carbon nanotubes. The resulting catalysts selectively contained Fe-Nx, Fe-Fe3C@C, and N-doped carbon (C-Nx) sites. It was revealed that Fe-Nx sites dominantly catalyze ORR via 4-electron (4 e(-)) pathway, exerting a major role for high ORR activity, whereas Fe-Fe3C@C sites mainly promote 2 e(-) reduction of oxygen followed by 2 e(-) peroxide reduction, playing an auxiliary role.

  10. Palladium(II)-Catalyzed C-H Bond Activation/C-C and C-O Bond Formation Reaction Cascade: Direct Synthesis of Coumestans. (United States)

    Neog, Kashmiri; Borah, Ashwini; Gogoi, Pranjal


    A palladium catalyzed cascade reaction of 4-hydroxycoumarins and in situ generated arynes has been developed for the direct synthesis of coumestans. This cascade strategy proceeds via C-H bond activation/C-O and C-C bond formations in a single reaction vessel. This methodology affords moderate to good yields of coumestans and is tolerant of a variety of functional groups including halide. The methodology was applied to the synthesis of natural product flemichapparin C.

  11. Formación de enlaces C-C, C-N y N-N con catalizadores de óxido de cerio y de oro/óxido de cerio.


    Cómbita Merchán, Diego Fernando


    [EN] Heterogeneous catalysis is one of the most important tools in the advancement of green chemistry, understood it as one that efficiently uses (preferably renewable) raw materials, eliminate waste and avoids the use of toxic and/or dangerous reagents and solvents in chemicals production and application. In this thesis we have investigated the reaction mechanisms and the nature of the active centers in C-C, C-N and N-N bond forming reactions over cerium oxide and over gold nanoparticles...

  12. 27 CFR 26.68 - Bond, Form 2898-Beer. (United States)


    ... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Bond, Form 2898-Beer. 26... Liquors and Articles in Puerto Rico Bonds § 26.68 Bond, Form 2898—Beer. Where a brewer intends to withdraw, for purpose of shipment to the United States, beer of Puerto Rican manufacture from bonded storage...

  13. 27 CFR 26.67 - Bond, Form 2897-Wine. (United States)


    ... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Bond, Form 2897-Wine. 26... Liquors and Articles in Puerto Rico Bonds § 26.67 Bond, Form 2897—Wine. Where a proprietor intends to withdraw, for purpose of shipment to the United States, wine of Puerto Rican manufacture from...

  14. Structure and reactivity of bis(silyl) dihydride complexes (PMe(3))(3)Ru(SiR(3))(2)(H)(2): model compounds and real intermediates in a dehydrogenative C-Si bond forming reaction. (United States)

    Dioumaev, Vladimir K; Yoo, Bok R; Procopio, Leo J; Carroll, Patrick J; Berry, Donald H


    A series of stable complexes, (PMe(3))(3)Ru(SiR(3))(2)(H)(2) ((SiR(3))(2) = (SiH(2)Ph)(2), 3a; (SiHPh(2))(2), 3b; (SiMe(2)CH(2)CH(2)SiMe(2)), 3c), has been synthesized by the reaction of hydridosilanes with (PMe(3))(3)Ru(SiMe(3))H(3) or (PMe(3))(4)Ru(SiMe(3))H. Compounds 3a and 3c adopt overall pentagonal bipyramidal geometries in solution and the solid state, with phosphine and silyl ligands defining trigonal bipyramids and ruthenium hydrides arranged in the equatorial plane. Compound 3a exhibits meridional phosphines, with both silyl ligands equatorial, whereas the constraints of the chelate in 3c result in both axial and equatorial silyl environments and facial phosphines. Although there is no evidence for agostic Si-H interactions in 3a and 3b, the equatorial silyl group in 3c is in close contact with one hydride (1.81(4) A) and is moderately close to the other hydride (2.15(3) A) in the solid state and solution (nu(Ru.H.Si) = 1740 cm(-)(1) and nu(RuH) = 1940 cm(-)(1)). The analogous bis(silyl) dihydride, (PMe(3))(3)Ru(SiMe(3))(2)(H)(2) (3d), is not stable at room temperature, but can be generated in situ at low temperature from the 16e(-) complex (PMe(3))(3)Ru(SiMe(3))H (1) and HSiMe(3). Complexes 3b and 3d have been characterized by multinuclear, variable temperature NMR and appear to be isostructural with 3a. All four complexes exhibit dynamic NMR spectra, but the slow exchange limit could not be observed for 3c. Treatment of 1 with HSiMe(3) at room temperature leads to formation of (PMe(3))(3)Ru(SiMe(2)CH(2)SiMe(3))H(3) (4b) via a CH functionalization process critical to catalytic dehydrocoupling of HSiMe(3) at higher temperatures. Closer inspection of this reaction between -110 and -10 degrees C by NMR reveals a plethora of silyl hydride phosphine complexes formed by ligand redistribution prior to CH activation. Above ca. 0 degrees C this mixture converts cleanly via silane dehydrogenation to the very stable tris(phosphine) trihydride carbosilyl complex 4b

  15. Supramolecular gel-assisted synthesis of double shelled Co@CoO@N-C/C nanoparticles with synergistic electrocatalytic activity for the oxygen reduction reaction (United States)

    Wu, Zexing; Wang, Jie; Han, Lili; Lin, Ruoqian; Liu, Hongfang; Xin, Huolin L.; Wang, Deli


    Investigating active, stable, and low-cost materials for the oxygen reduction reaction is one of the key challenges in fuel-cell research. In this work, we describe the formation of N-doped carbon shell coated Co@CoO nanoparticles supported on Vulcan XC-72 carbon materials (Co@CoO@N-C/C) based on a simple supramolecular gel-assisted method. The double-shelled Co@CoO@N-C/C core-shell nanoparticles exhibit superior electrocatalytic activities for the oxygen reduction reaction compared to N-doped carbon and cobalt oxides, demonstrating the synergistic effect of the hybrid nanomaterials. Notably, the Co@CoO@N-C/C nanoparticles give rise to a comparable four-electron selectivity, long-term stability, and high methanol tolerance; all show a multi-fold improvement over the commercial Pt/C catalyst. The progress is of great importance in exploring advanced non-precious metal-based electrocatalysts for fuel cell applications.Investigating active, stable, and low-cost materials for the oxygen reduction reaction is one of the key challenges in fuel-cell research. In this work, we describe the formation of N-doped carbon shell coated Co@CoO nanoparticles supported on Vulcan XC-72 carbon materials (Co@CoO@N-C/C) based on a simple supramolecular gel-assisted method. The double-shelled Co@CoO@N-C/C core-shell nanoparticles exhibit superior electrocatalytic activities for the oxygen reduction reaction compared to N-doped carbon and cobalt oxides, demonstrating the synergistic effect of the hybrid nanomaterials. Notably, the Co@CoO@N-C/C nanoparticles give rise to a comparable four-electron selectivity, long-term stability, and high methanol tolerance; all show a multi-fold improvement over the commercial Pt/C catalyst. The progress is of great importance in exploring advanced non-precious metal-based electrocatalysts for fuel cell applications. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr07929b

  16. Pd loaded amphiphilic COF as catalyst for multi-fold Heck reactions, C-C couplings and CO oxidation. (United States)

    Mullangi, Dinesh; Nandi, Shyamapada; Shalini, Sorout; Sreedhala, Sheshadri; Vinod, Chathakudath P; Vaidhyanathan, Ramanathan


    COFs represent a class of polymers with designable crystalline structures capable of interacting with active metal nanoparticles to form excellent heterogeneous catalysts. Many valuable ligands/monomers employed in making coordination/organic polymers are prepared via Heck and C-C couplings. Here, we report an amphiphilic triazine COF and the facile single-step loading of Pd(0) nanoparticles into it. An 18-20% nano-Pd loading gives highly active composite working in open air at low concentrations (Conc. Pd(0) couplings and C-C couplings using 'non-boronic acid' substrates, and exhibits good recyclability with no sign of catalyst leaching. As an oxidation catalyst, it shows 100% conversion of CO to CO2 at 150 °C with no loss of activity with time and between cycles. Both vapor sorptions and contact angle measurements confirm the amphiphilic character of the COF. DFT-TB studies showed the presence of Pd-triazine and Pd-Schiff bond interactions as being favorable.

  17. Catalytic diastereoselective tandem conjugate addition-elimination reaction of Morita-Baylis-Hillman C adducts by C-C bond cleavage

    KAUST Repository

    Yang, Wenguo


    Through the cleavage of the C-C bond, the first catalytic tandem conjugate addition-elimination reaction of Morita-Baylis-Hillman C adducts has been presented. Various S N2′-like C-, S-, and P-allylic compounds could be obtained with exclusive E configuration in good to excellent yields. The Michael product could also be easily prepared by tuning the β-C-substituent group of the α-methylene ester under the same reaction conditions. Calculated relative energies of various transition states by DFT methods strongly support the observed chemoselectivity and diastereoselectivity. © 2012 Wiley-VCH Verlag GmbH&Co. KGaA, Weinheim.

  18. Microwave-Assisted Olefination Reaction of Alkylzinc with Aromatic Aldehyde Catalyzed by Nickel Complex

    Institute of Scientific and Technical Information of China (English)

    MEN Xiu-Qin; WANG Jin-Xian; SHI Xiao-Ning; WANG Ke-Hu


    @@ Carbon-carbon double bond-forming reactions have always been great importance in organic synthesis. Manymethods have been described for C =C bond formation. We[1] have reported the new method of C =C bond formation of nickel catalyzed organozinc with aromatic aldehydes in the presence of Me3SiC1.

  19. The new C-C bond formation in the reaction of o-amidophenolate indium(III) complex with alkyl iodides. (United States)

    Piskunov, Alexandr V; Meshcheryakova, Irina N; Fukin, Georgy K; Shavyrin, Andrei S; Cherkasov, Vladimir K; Abakumov, Gleb A


    The reaction of bis(4,6-di-tert-butyl-N-(2,6-di-iso-propylphenyl)-o-amidophenolato)indium(III) anion with alkyl iodides is reported. This process includes oxidative addition of two RI (R = Me, Et) molecules to the non-transition metal complex and results in an alkyl transfer to ring carbon atoms with the formation of two new C-C bonds. The interaction proceeds at mild conditions and gives new indium(III) derivatives containing iminocyclohexa-1,4-dienolate type ligands.

  20. A model for particle production in nuclear reactions at intermediate energies: application to C-C collisions at 95 MeV/nucleon

    CERN Document Server

    Dudouet, Jérémie


    A model describing nuclear collisions at intermediate energies is presented and the results are compared with recently measured double differential cross sections in C-C reactions at 95 MeV/nucleon. Results show the key role played by geometrical effects and the memory of the entrance channel, in particular the momentum distributions of the two incoming nuclei. Special attention is paid to the description of processes occurring at mid-rapidity. To this end, a random particle production mechanism by means of a coalescence process in velocity space is considered in the overlap region of the two interacting nuclei.

  1. Free-Radical Triggered Ordered Domino Reaction: An Approach to C-C Bond Formation via Selective Functionalization of α-Hydroxyl-(sp(3))C-H in Fluorinated Alcohols. (United States)

    Xu, Zhengbao; Hang, Zhaojia; Liu, Zhong-Quan


    A free-radical mediated highly ordered radical addition/cyclization/(sp(3))C-C(sp(3)) formation domino reaction is developed. Three new C-C bonds are formed one by one in a mixed system. Furthermore, it represents the first example of cascade C-C bond formation via selective functionalization of α-hydroxyl-C(sp(3))-H in fluorinated alcohols.

  2. Copper(I)- and copper(0)-promoted homocoupling and homocoupling-hydrodehalogenation reactions of dihalogenoclathrochelate precursors for C-C conjugated iron(II) bis-cage complexes. (United States)

    Varzatskii, Oleg A; Shul'ga, Sergey V; Belov, Alexander S; Novikov, Valentin V; Dolganov, Alexander V; Vologzhanina, Anna V; Voloshin, Yan Z


    Iron(II) dibromo- and diiodoclathrochelates undergo copper(I)-promoted reductive homocoupling in HMPA at 70-80 °C leading to C-C conjugated dibromo- and diiodo-bis-clathrochelates in high yields. Under the same conditions, their dichloroclathrochelate analog does not undergo the same homocoupling reaction, so the target dichloro-bis-cage product was obtained in high yield via dimerization of its heterodihalogenide iodochloromonomacrobicyclic precursor. The use of NMP as a solvent at 120-140 °C gave the mixture of bis-clathrochelates resulting from a tandem homocoupling-hydrodehalogenation reaction: the initial acetonitrile copper(I) solvato-complex at a high temperature underwent re-solvatation and disproportionation leading to Cu(II) ions and nano-copper, which promoted the hydrodehalogenation process even at room temperature. The most probable pathway of this reaction in situ includes hydrodehalogenation of the already formed dihalogeno-bis-clathrochelate via the formation of reduced anion radical intermediates. As a result, chemical transformations of the iron(II) dihalogenoclathrochelates in the presence of an acetonitrile copper(I) solvato-complex were found to depend both on the nature of halogen atoms in their ribbed chelate fragments and on reaction conditions (i.e. solvent and temperature). The C-C conjugated iron(II) dihalogeno-bis-clathrochelates easily undergo nucleophilic substitution with various N,S-nucleophiles giving ribbed-functionalized bis-cage species. These iron(II) complexes were characterized by elemental analysis, MALDI-TOF mass spectrometry, IR, UV-Vis, (1)H and (13)C NMR spectroscopy, and by X-ray diffraction; their electrochemical properties were studied by cyclic voltammetry. The isomeric shift values in (57)Fe Mössbauer spectra of such cage compounds allowed identifying them as low-spin iron(II) complexes, while those of the quadrupole splitting are the evidence for a significant TP distortion of their FeN6-coordination polyhedra

  3. Catalytic Upgrading of Biomass-Derived Compounds via C-C Coupling Reactions. Computational and Experimental Studies of Acetaldehyde and Furan Reactions in HZSM-5

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Cong [Argonne National Lab. (ANL), Argonne, IL (United States); Evans, Tabitha J. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Cheng, Lei [Argonne National Lab. (ANL), Argonne, IL (United States); Nimlos, Mark R. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Mukarakate, Calvin [National Renewable Energy Lab. (NREL), Golden, CO (United States); Robichaud, David J. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Assary, Rajeev S. [Argonne National Lab. (ANL), Argonne, IL (United States); Curtiss, Larry A. [Argonne National Lab. (ANL), Argonne, IL (United States)


    These catalytic C–C coupling and deoxygenation reactions are essential for upgrading of biomass-derived oxygenates to fuel-range hydrocarbons. Detailed understanding of mechanistic and energetic aspects of these reactions is crucial to enabling and improving the catalytic upgrading of small oxygenates to useful chemicals and fuels. Using periodic density functional theory (DFT) calculations, we have investigated the reactions of furan and acetaldehyde in an HZSM-5 zeolite catalyst, a representative system associated with the catalytic upgrading of pyrolysis vapors. Comprehensive energy profiles were computed for self-reactions (i.e., acetaldehyde coupling and furan coupling) and cross-reactions (i.e., acetaldehyde + furan) of this representative mixture. Major products proposed from the computations are further confirmed using temperature controlled mass spectra measurements. Moreover, the computational results show that furan interacts with acetaldehyde in HZSM-5 via an alkylation mechanism, which is more favorable than the self-reactions, indicating that mixing furans with aldehydes could be a promising approach to maximize effective C–C coupling and dehydration while reducing the catalyst deactivation (e.g., coke formation) from aldehyde condensation.

  4. Allele-specific oligonucleotide polymerase chain reaction for the determination of Rh C/c and Rh E/e antigens in thalassaemic patients (United States)

    Hojjati, Mohammad Taher; Einollahi, Nahid; Nabatchian, Fariba; Pourfathollah, Ali Akbar; Mahdavi, Mohammad Reza


    Background Thalassaemia is a genetic disease in which there is a relative or complete lack of alpha or beta globin chains. Patients with moderate to severe forms of thalassaemia need transfusions from the early years of life. Antibody production against blood group antigens may cause many problems in preparing compatible blood units for transfusion. The identification of definite blood group phenotypes by the haemagglutination method can be difficult because of the mixed population of red blood cells from the donor and recipient. Materials and methods Forty multiply transfused thalassaemic patients and ten healthy controls with no history of blood transfusion were enrolled in this study. Allele-specific oligonucleotide polymerase chain reaction (ASO-PCR) and haemagglutination methods were used to determine the presence of Rhesus (Rh) C, c, E and e antigens. Results In this study four primer sets were used for ASO-PCR amplification of RhC/c and RhE/e. Although PCR assays for RhC/c and RHE/e genotyping have been described previously, in this study we used a new condition for PCR by decreasing the annealing temperature from 63 °C to 58 °C in order to amplify all four genes in the same condition. In order to evaluate this single run molecular method, we used the haemagglutination test as the standard method and compared the results from the two methods. We found discrepancies between phenotype and genotype results among patients with beta thalassaemia, but complete agreement between phenotype and genotype in the control group. Conclusions The advantage of this new ASO-PCR method compared to a restriction fragment length polymorphism (RFLP) PCR method is that with the former all four genes can be amplified at the same time by PCR, and electrophoresis can be performed immediately to determine individual antigen profiles. The simplicity of the ASO-PCR method makes it suitable for routine use in medical centres and it is also cheaper than RFLP-PCR. Furthermore, as shown

  5. Building Bridges: Biocatalytic C-C-Bond Formation toward Multifunctional Products. (United States)

    Schmidt, Nina G; Eger, Elisabeth; Kroutil, Wolfgang


    Carbon-carbon bond formation is the key reaction for organic synthesis to construct the carbon framework of organic molecules. The review gives a selection of biocatalytic C-C-bond-forming reactions which have been investigated during the last 5 years and which have already been proven to be applicable for organic synthesis. In most cases, the reactions lead to products functionalized at the site of C-C-bond formation (e.g., α-hydroxy ketones, aminoalcohols, diols, 1,4-diketones, etc.) or allow to decorate aromatic and heteroaromatic molecules. Furthermore, examples for cyclization of (non)natural precursors leading to saturated carbocycles are given as well as the stereoselective cyclopropanation of olefins affording cyclopropanes. Although many tools are already available, recent research also makes it clear that nature provides an even broader set of enzymes to perform specific C-C coupling reactions. The possibilities are without limit; however, a big library of variants for different types of reactions is required to have the specific enzyme for a desired specific (stereoselective) reaction at hand.

  6. Efficient catalysis of Suzuki–Miyaura C-C coupling reactions with palladium(II) complexes of partially hydrolyzed bisimine ligands: A process important in environment context

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Arun; Rao, Gyandshwar Kumar; Saleem, Fariha; Kumar, Rupesh; Singh, Ajai K., E-mail:


    Graphical abstract: - Highlights: • Syntheses of hexadentate chalcogenated (S/Se/Te) bisimine ligands. • Reactions with Pd(II) resulted in their metal promoted partial hydrolysis to 1-[C(CH{sub 3})=N-(CH{sub 2}){sub 2}-EAr]-3-[C(CH{sub 3})=O]-4,6-[OH]{sub 2}C{sub 6}H{sub 2} and ArE-(CH{sub 2}){sub 2}-NH{sub 2}. • Isolation and characterization of Pd(II) complexes of products of hydrolysis. • Exploration of catalytic potential of Pd(II) complexes for Suzuki coupling. • Highest catalytic efficiency of complex of Se based ligand which shows activity for coupling aryl chlorides. - Abstract: Potentially hexadentante [O{sup −},N,E:E,N,O{sup −}] chalcogenated bisimine ligands L1–L3 have been synthesized by reaction of 1,1′-(4,6-dihydroxy-1,3-phenylene)bisethanone with H{sub 2}N-(CH{sub 2}){sub 2}-S-Ph, H{sub 2}N-(CH{sub 2}){sub 2}-Se-Ph and H{sub 2}N-(CH{sub 2}){sub 2}-Te-C{sub 6}H{sub 4}-4-OMe respectively. The L1–L3 react with Na{sub 2}PdCl{sub 4} resulting in their partial hydrolysis, which appears to be metal-promoted. Of the two [-(CH{sub 3})C=N-(CH{sub 2}){sub 2}-EAr] fragments of L1–L3, one is converted to -(CH{sub 3})C=O and H{sub 2}N-(CH{sub 2}){sub 2}-E-Ar eliminated. The hydrolysis products 1-[C(CH{sub 3})=N-(CH{sub 2}){sub 2}-SPh]-3-[C(CH{sub 3})=O]-4,6-[OH]{sub 2}C{sub 6}H{sub 2} (L1′), 1-[C(CH{sub 3})=N-(CH{sub 2}){sub 2}-SePh]-3-[C(CH{sub 3})=O]-4,6-[OH]{sub 2}C{sub 6}H{sub 2} (L2′) and 1-[C(CH{sub 3})=N-(CH{sub 2}){sub 2}-Te-C{sub 6}H{sub 4}-4-OMe]-3-[C(CH{sub 3})=O]-4,6-[OH]{sub 2}C{sub 6}H{sub 2} (L3′) have formed complexes [PdCl(L′–H)] (1, 3 and 5). The other product of hydrolysis H{sub 2}N-(CH{sub 2}){sub 2}-E-Ar (L″) reacted with Na{sub 2}PdCl{sub 4} yielding the complexes [PdL”Cl{sub 2}] (2, 4 and 6). All the complexes (1–6) were found thermally and air stable. Complexes 1, 3 and 5 have been investigated as catalysts for Suzuki–Miyaura C-C coupling reactions. The catalytic activities of 1 and 3 which are

  7. Copper-catalyzed asymmetric allylic substitution reactions with organozinc and Grignard reagents

    NARCIS (Netherlands)

    Geurts, Koen; Fletcher, Stephen P.; van Zijl, Anthoni W.; Minnaard, Adriaan J.; Feringa, Ben L.; Bignall, H. E.; Jauncey, D. L.; Lovell, J. E. J.; Tzioumis, A. K.; Kedziora-Chudczer, L. L.; MacQuart, J. P.; Tingay, S. J.; Rayner, D. P.; Clay, R. W.


    Asymmetric allylic alkylations (AAAs) are among the most powerful C-C bond-forming reactions. We present a brief overview of copper-catalyzed AAAs with organometallic reagents and discuss our own contributions to this field. Work with zinc reagents and phosphoramidite ligands provided a framework fo

  8. 46 CFR 308.532 - Release of surety bond, Form MA-312. (United States)


    ... 46 Shipping 8 2010-10-01 2010-10-01 false Release of surety bond, Form MA-312. 308.532 Section 308.532 Shipping MARITIME ADMINISTRATION, DEPARTMENT OF TRANSPORTATION EMERGENCY OPERATIONS WAR RISK..., Form MA-312. The Standard Form of Release of Surety bond, Form MA-312, may be obtained from...

  9. Nickel(II) complexes containing ONS donor ligands: Synthesis, characterization, crystal structure and catalytic application towards C-C cross-coupling reactions

    Indian Academy of Sciences (India)

    Panneerselvam Anitha; Rajendran Manikandan; Paranthaman Vijayan; Govindan Prakash; Periasamy Viswanathamurthi; Ray Jay Butcher


    Nickel(II) complexes containing thiosemicarbazone ligands [Ni(L)2] (1-3) (L = 9,10-phenanthrenequinonethiosemicarbazone (HL1), 9,10-phenanthrenequinone-N-methylthio semicarbazone (HL2) and 9, 10-phenanthrenequinone-N-phenylthiosemicarbazone (HL3)) have been synthesized and characterized by elemental analysis and spectroscopic (IR, UV-Vis, 1H, 13C-NMR and ESI mass) methods. The molecular structures of complexes 1 and 2 were identified by means of single-crystal X-ray diffraction analysis. The analysis revealed that the complexes possess a distorted octahedral geometry with the ligand coordinating in a uni-negative tridentate ONS fashion. The catalytic activity of complexes towards some C–C coupling reactions (viz., Kumada-Corriu, Suzuki-Miyaura and Sonogashira) has been examined. The complexes behave as efficient catalysts in the Kumada-Corriu and Sonogashira coupling reactions rather than Suzuki-Miyaura coupling.

  10. Synthesis, Crystal Structure of Ruthenium 1,2-Naphthoquinone-1-oxime Complex and Its Mediated C-C Coupling Reactions of Terminal Alkynes

    Institute of Scientific and Technical Information of China (English)

    SUN, Ke; WONG, Wing-Tak; LIU, Xiao-Xia; ZHANG, Bao-Yan


    Substituted decarbonylation reaction of ruthenium 1,2-naphthoquinone-1-oxime (1-nqo) complex, cis-, cis-[Ru{ η2-N(O)C10-H6O}2(CO)2] (1), with acetonitrile gave cis-, cis-[Ru { η2-N(O)C10H6O}2(CO)(NCMe)] (2). Complex 2 was fully characterized by 1H NMR, FAB MS, IR spectra and single crystal X-ray analysis. Complex 2 maintains the coordination structure of 1 with the two naphthoquinonic oxygen atoms, as well as the two oximato nitrogen atoms located cis to each other, showing that there is no ligand rearrangement of the 1-nqo ligands during the substitution reaction. The carbonyl group originally trans to the naphthoquinonic oxygen in one 1-nqo ligand is left in its original position [O(5)-Ru-C(1), 174.0(6)°], while the other one originally trans to the oximato group of the other 1-nqo llgand is substituted by NCMe [N(1)-Ru-N(3), 170.6(6)°].This shows that the carbonyl trans to oximato group is more labile than the one trans to naphthoquinonic O atom towards substitution. This is probably due to the comparatively stronger π back bonding from ruthenium metal to the carbonyl group trans to naphthoquinonic O atom, than the one trans to oximato group, resulting in the comparatively weaker Ru-CO bond for the latter and consequently easier replacement of this carbonyl. Selected coupling of phenylacetylene mediated by 2 gave a single trans-dimerization product 3, while 2 mediated coupling reaction of methyl propiolate produced three products:one trans-dimerization product 4 and two cyclotrimeric products 5 and 6.

  11. Solid-state Photochemical [2+2] Cycloaddition Reaction of Hydrogen-Bonded Zn(II) Metal Complex Containing Several Parallel C=C Bonds

    Indian Academy of Sciences (India)



    A 2D hydrogen-bonded dinuclear Zn(II) complex, [{Zn(H₂O) ₃ (bpe) ₂} ₂ (bpe)](NO₃) ₄・3bpe・14H₂O,1 (bpe = 4,4_-bipyridylethylene) containing coordination complex cations, [{Zn(H₂O) ₃ (bpe) ₂} ₂ (μ-bpe)] ⁴⁺and free bpe and lattice water molecules shows face-to-face, π ・ ・ ・ π stacking of two of the four free bpemolecules with coordinated bpe ligands. Out of eight bpe molecules, six are aligned in parallel fashion withshort C・ ・ ・ C distances of 3.663–3.814Å and they undergo photochemical [2+2] cycloaddition reaction. The photoreaction conducted on ground sample of 1 in the solid-state affords rctt-tetrakis(4-pyridyl)cyclobutane (rctt-tpcb) product in 75% yield. The molecular movement of free bpe molecules was tested by conducting thephotoreaction in ground sample and heated sample of single crystals. The photoreactivity study of 1 indicates that the free bpe molecules are locked between the cationic [{Zn(H₂O) ₃ (bpe) ₂} ₂ (bpe)] ⁴⁺ layers.

  12. 46 CFR 308.530 - Letter requesting increase or decrease in amount of surety bond, Form MA-310. (United States)


    ... surety bond, Form MA-310. 308.530 Section 308.530 Shipping MARITIME ADMINISTRATION, DEPARTMENT OF... Insurance § 308.530 Letter requesting increase or decrease in amount of surety bond, Form MA-310. An endorsement increasing or decreasing the amount of the surety bond, Form MA-310, shall be transmitted to...

  13. Reactions of a 16-electron Cp*Co half-sandwich complex containing a chelating 1,2-dicarba-closo-dodecaborane-1,2-dithiolate ligand with alkynones HC≡C-C(O)R (R=OMe,Me,Ph)

    Institute of Scientific and Technical Information of China (English)

    GUOYIQIBAYI; Gulnisa


    The reaction of the 16e half-sandwich complex Cp*Co(S2C2B10H10) (1) (Cp* = pentamethylcyclopentadienyl) with excess methyl acetylene monocarboxylate, HC≡C-CO2Me, affords the 18e complexes 2-6. Compound 2 bears a B-CH2 unit in which B-substitution occurs in the B(3)/B(6) position of the ortho-carborane cage. Complexes 3-6 are geometrical isomers, in which the alkyne is twofold inserted into one of the Co-S bonds in all the four possible ways. Treatment of 1 with excess 3-butyn-2-one or phenyl ethynyl ketone, HC≡C-C(O)R (R = Me, Ph), at ambient temperature leads to the 18e complexes 7-10, respectively, with two alkynes inserted into one of the Co-S bonds. All the new complexes were fully characterized by spectroscopic techniques and elemental analysis. The solid-state structures of 2, 3, 5, 7, 8, 9 and 10 were further characterized by X-ray structural analysis.

  14. Anomalous absorption in c-C_3H and c-C_3D radicals (United States)

    Chandra, S.; Shinde, S. V.; Kegel, W. H.; Sedlmayr, E.

    Yamamoto et al. (1987) reported the first detection of the c-C_3H radical in TMC-1 through its transition 2_1 2 rightarrow 1_1 1 at 91.5 GHz. The column density of c-C_3H in TMC-1 was estimated to be 6 times 10^12 cm^-2, which is about one order of magnitude lower than that of the c-C_3H_2 which is ubiquitous in galactic objects. Mangum & Wootten (1990) detected c-C_3H through the transition 1_1 0 rightarrow 1_1 1 at 14.8 GHz in 12 additional galactic objects. The most probable production mechanism of both the c-C_3H and c-C_3H_2 in dark clouds is a common dissociation reaction of the C_3H_3^+ ion (Adams & Smith 1987). Although the c-C_3H is 0.8 eV less stable than its isomer l-C_3H, finding of comparable column densities of both the isomers in TMC-1 suggests that the formation rate for both, c-C_3H and l-C_3H, are of about the same order in the cosmic objects. The existence of a metastable isomer under interstellar conditions is a well known phenomenon in astronomy. The aim of this investigation is a quantitative estimate of relative line intensities under NLTE conditions. For wide ranges of physical parameters, where these molecules may be found, we have solved a set of statistical equilibrium equations coupled with the equations of radiative transfer in an on-the-spot approximation. For c-C_3H, we accounted for 51 energy levels connected by 207 radiative transitions and for c-C_3D, we accounted for 51 energy levels connected by 205 radiative transitions. Our results show that the 3_3 1 rightarrow 3_3 0 transition of c-C_3H and c-C_3D may be found in absorption against the cosmic microwave background (CMB). Furthermore, we found population inversion for the 1_1 0 rightarrow 1_1 1 transition. These findings may be useful in identifying these molecules in other cosmic objects, as well as for the determination of physical parameters in these objects.

  15. Phenalenyl-based ligand for transition metal chemistry: Application in Henry reaction

    Indian Academy of Sciences (India)

    Arup Mukherjee; Tamal K Sen; Swadhin K Mandal; Daniel Kratzert; Dietmar Stalke; Alexander Döring; Carola Schulzke


    We report the synthesis and characterization of the first transition metal complex of a phenalenylbased ligand. The reaction of Cu(OAc)2.H2O with 9--methylamino-1-'-methylimino-phenalene (LH) in 1:1 stoichiometric ratio results in the formation of a mononuclear copper complex [LCu(OAc)] (1). The molecular structure of 1 was established by X-ray crystallography. The electrochemistry of 1 indicates the formation of an anionic radical by one electron reduction into the non-bonding molecular orbital of the phenalenyl system. The complex 1 efficiently catalyses the C-C bond forming Henry reaction.

  16. C/C-PAA与C/C-FA弯曲性能对比%Comparison of Flexural Properties Between C/C-PAA and C/C-FA

    Institute of Scientific and Technical Information of China (English)

    张万强; 赵英民; 王涛; 詹万初



  17. Ruthenium(II)-Catalyzed C-C Arylations and Alkylations: Decarbamoylative C-C Functionalizations. (United States)

    Moselage, Marc; Li, Jie; Kramm, Frederik; Ackermann, Lutz


    Ruthenium(II)biscarboxylate catalysis enabled selective C-C functionalizations by means of decarbamoylative C-C arylations. The versatility of the ruthenium(II) catalysis was reflected by widely applicable C-C arylations and C-C alkylations of aryl amides, as well as acids with modifiable pyrazoles, through facile organometallic C-C activation.

  18. T heoretical study of mechanism for C -C, C- H bond activation in spin-forbidden reaction betw een Zr and 2-butyne%Zr(F3)与2-丁炔分子自旋禁阻反应C-C,C-H键活化机理的理论研究

    Institute of Scientific and Technical Information of China (English)

    王永成; 马盼盼; 王文雪


    运用密度泛函理论(DFT )B3LYP方法研究了单重态和三重态势能面自旋禁阻反应Zr活化2‐丁炔分子的C—C和C— H键的反应机理.通过自旋‐轨道耦合的计算讨论了势能面交叉点和可能的自旋翻转过程.反应从基态三重态开始,在活化C—C键的反应过程中出现了自旋态的改变,使得过渡态3 T4g的活化能垒从-3.58降到-10.60 kJ· mol-1.在M ECP4处,单重态和三重态间的自旋‐轨道耦合常数为146.10 cm -1,反应发生有效的系间窜越,从三重态跃迁到单重态势能面,反应势垒有所下降.%The mechanism of the spin‐forbidden reaction Zr (3 F) and 2‐butyne on singlet and triplet potential energy surface(PESs) has been investigated by DFT of B3LYP .Crossing points between the different potential energy surfaces and the possible spin inversion process are discussed by spin‐orbit coupling (SOC) calculations . The reacting system starts in the triplet ground state , the changes of the spin state probably occur the activation of C—C , lead to a significant decrease in the barrier height of transition state 3 T4g from -3.58 to -10.60 kJ·mol-1 . The values of the SOC constants at minimum energy crossing point (MECP4) are 146.10 cm -1 between singlet and triplet PESs . The effective intersystem crossing (ISC) between different triplet and singlet PESs can occur and obviously reduce energy barriers .

  19. Rhodium-Catalyzed C-C Bond Formation via Heteroatom-Directed C-H Bond Activation

    Energy Technology Data Exchange (ETDEWEB)

    Colby, Denise; Bergman, Robert; Ellman, Jonathan


    Once considered the 'holy grail' of organometallic chemistry, synthetically useful reactions employing C-H bond activation have increasingly been developed and applied to natural product and drug synthesis over the past decade. The ubiquity and relative low cost of hydrocarbons makes C-H bond functionalization an attractive alternative to classical C-C bond forming reactions such as cross-coupling, which require organohalides and organometallic reagents. In addition to providing an atom economical alternative to standard cross - coupling strategies, C-H bond functionalization also reduces the production of toxic by-products, thereby contributing to the growing field of reactions with decreased environmental impact. In the area of C-C bond forming reactions that proceed via a C-H activation mechanism, rhodium catalysts stand out for their functional group tolerance and wide range of synthetic utility. Over the course of the last decade, many Rh-catalyzed methods for heteroatom-directed C-H bond functionalization have been reported and will be the focus of this review. Material appearing in the literature prior to 2001 has been reviewed previously and will only be introduced as background when necessary. The synthesis of complex molecules from relatively simple precursors has long been a goal for many organic chemists. The ability to selectively functionalize a molecule with minimal pre-activation can streamline syntheses and expand the opportunities to explore the utility of complex molecules in areas ranging from the pharmaceutical industry to materials science. Indeed, the issue of selectivity is paramount in the development of all C-H bond functionalization methods. Several groups have developed elegant approaches towards achieving selectivity in molecules that possess many sterically and electronically similar C-H bonds. Many of these approaches are discussed in detail in the accompanying articles in this special issue of Chemical Reviews. One approach

  20. Radical Reactions and Its Synthetic Application

    Institute of Scientific and Technical Information of China (English)

    Takeaki Naito


    @@ 1Introduction Strategies involving radical reactions have become preeminent tools in organic synthesis. Free radical-mediated cyclization has developed as a powerful method for preparing various types of cyclic compounds via carbon-carbon bond-forming processes. In order to develop effective and convenient methods for the synthesis of biologically active cyclic amines, we have focused our efforts on radical reactions using aldehydes, ketones,and C-C multiple bonds as a radical precursor and/or an oxime ether, hydrazone, and nitrone as a radical acceptor. In this lecture, I would like to talk on radical addition-cyclization of oxime ether and its application to the synthesis of martinellines.

  1. Pictet-Spengler condensation reactions catalyzed by a recyclable H~+-montmorillonite as a heterogeneous BrΦnsted acid

    Institute of Scientific and Technical Information of China (English)


    Catalytic performance of different cation-exchanged montmorillonite clays has been investigated in the Pictet-Spengler C-C bond forming reaction.H+-Montmorillonite was found to be a very efficient and reusable catalyst for the endo cyclization of β-phenylethylamine derivatives with aldehydes under solvent-free conditions.In addition,an aqueous condensation version for the synthesis of tetrahydro-β-carbolines using the H+-montmorillonite catalyst has been developed.In these environmentally friendly processes,the use of organic solvents was avoided and the catalyst was recycled with maintenance of high catalytic activity.

  2. N,N-bond-forming heterocyclization: synthesis of 3-alkoxy-2H-indazoles. (United States)

    Mills, Aaron D; Nazer, Musa Z; Haddadin, Makhluf J; Kurth, Mark J


    A one-step heterocyclization of o-nitrobenzylamines to 3-alkoxy-2H-indazoles is reported. The electronic nature of the nitrophenyl group, the steric and electronic nature of the R1-functionalized benzylic amine, and the nature of the alcoholic solvent affect the efficiency of this heterocyclization reaction (approximately 40-90%).

  3. Understanding reaction mechanisms in organic chemistry from catastrophe theory applied to the electron localization function topology. (United States)

    Polo, Victor; Andres, Juan; Berski, Slawomir; Domingo, Luis R; Silvi, Bernard


    Thom's catastrophe theory applied to the evolution of the topology of the electron localization function (ELF) gradient field constitutes a way to rationalize the reorganization of electron pairing and a powerful tool for the unambiguous determination of the molecular mechanisms of a given chemical reaction. The identification of the turning points connecting the ELF structural stability domains along the reaction pathway allows a rigorous characterization of the sequence of electron pair rearrangements taking place during a chemical transformation, such as multiple bond forming/breaking processes, ring closure processes, creation/annihilation of lone pairs, transformations of C-C multiple bonds into single ones. The reaction mechanism of some relevant organic reactions: Diels-Alder, 1,3-dipolar cycloaddition and Cope rearrangement are reviewed to illustrate the potential of the present approach.

  4. Exchanging Alkyl Groups through Unstrained C-C Bond Cleavage in the Presence of a Copper Catalyst. (United States)

    Wada, Masaru; Noda, Yushi; Nishikata, Takashi


    Although numerous reports exist on strained C-C bond cleavage reactions in aryl substitutions, the cleavage methodology for unstrained C-C bonds in alkylation reactions has not yet been established. We found that unstrained allylic C-C bonds can be cleaved using α-radicals to form C(sp(3) )-C(sp(3) ) bonds in the presence of a copper catalyst. In this reaction, the property of leaving and loading radicals is very important for radical fragmentations. In this paper, we investigated the effects of these properties in cleavage reactions for unstrained C-C bonds.

  5. Borane-catalyzed cracking of C-C bonds in coal; Boran-katalysierte C-C-Bindungungsspaltung in Steinkohle

    Energy Technology Data Exchange (ETDEWEB)

    Narangerel, J.; Haenel, M.W. [Max-Planck-Institut fuer Kohlenforschung, Muelheim an der Ruhr (Germany)


    Coal, especially coking coal, was reacted with hydrogen at comparatively mild reaction conditions (150-280 degrees centigrade, 20 MPa hydrogen pressure) in the presence of catalysts consisting of borange reagents and certain transition metal halides to obtaine more than 80 percent of pyridine-soluble products. The influence of the degree of coalification, catalyst and temperature on the borane-catalyzed hydrogenolysis of C-C bonds in coal was investigated. (orig.) [Deutsch] Steinkohlen, insbesondere im Inkohlungsbereich der Fettkohlen (Kokskohlen), werden in Gegenwart von Katalysatoren aus Boran-Reagentien und bestimmten Uebergangsmetallhalogeniden mit Wasserstoff bei vergleichsweise milden Reaktionsbedingungen (250-280 C, 20 MPa Wasserstoffdruck) in zu ueber 80% pyridinloesliche Produkte umgewandelt. Der Einfluss von Inkohlungsgrad, Katalysator und Temperatur auf die Boran-katalysierte C-C-Bindungshydrogenolyse in Kohle wurde untersucht. (orig.)

  6. Structural Phase Transformation (F. C. C. - B. C. C.) in F. C. C. Metals and Their Stability on the Path of Transformation (United States)

    Öztekýn, Yasemin; Çolakoðlu, Kemal


    Because of its importance in Solid-State Physics, Metalurgy, Solid Mechanics and geophysics, theoretical strength calculations are performed to locate the stress-free b.c.c phase on three f.c.c metals (Ca, Pb, Ir). Internal energies correspponding to the unstresed b.c.c. and f.c.c. phase, and the required stress and energy changes for f.c.c.-b.c.c. transformation for these crystals are computed. To determine the range of stability (G stability), the Born criterion is used by calculating the values of deformation connecting the stress-free b.c.c. and stress-free f.c.c. phases of Ca, Pb and Ir. The studied crystals are subjected to unconstrained (100) uniaxial tension in all computations, and E.G.E.P. (Extended generalized exponantial potential) model is used to carry out these calculations.

  7. Photoinduced C-C Cross-Coupling of Aryl Chlorides and Inert Arenes

    Directory of Open Access Journals (Sweden)

    Lele Wang


    Full Text Available Here we report a facile, efficient, and catalyst-free method to realize C-C cross-coupling of aryl chlorides and inert arenes under UV light irradiation. The aryl radical upon homolytic cleavage of C-Cl bond initiated the nucleophilic substitution reaction with inert arenes to give biaryl products. This mild reaction mode can also be applied to other synthetic reactions, such as the construction of C-N bonds and trifluoromethylated compounds.

  8. Thermoelectric properties of porous SiC/C composites

    NARCIS (Netherlands)

    Fujisawa, Masashi; Hata, Toshimitsu; Kitagawa, Hiroyuki; Bronsveld, Paul; Suzuki, Youki; Hasezaki, Kazuhiro; Noda, Yasutoshi; Imamura, Yuji


    We developed a porous SiC/C composite by oxidizing a SiC/C composite made from a mixed powder of wood charcoal and SiO2 (32-45 mu m) by pulse current sintering at 1600 and 1800 degrees C under a N-2 atmosphere. The microstructures of the porous SiC/C composites with oxidation and the SiC/C composite

  9. Manganese(I)-Catalyzed Dispersion-Enabled C-H/C-C Activation. (United States)

    Meyer, Tjark H; Liu, Weiping; Feldt, Milica; Wuttke, Axel; Mata, Ricardo A; Ackermann, Lutz


    C-H/C-C Functionalizations were achieved with the aid of a versatile manganese(I) catalyst. Thus, an organometallic manganese-catalyzed C-H activation set the stage for silver-free C-H/C-C transformations with ample substrate scope and excellent levels of chemo-, site-, and diastereo-selectivities. The robust nature of the manganese(I) catalysis regime was reflected by the first C-H/C-C functionalization on amino acids under racemization-free reaction conditions. Detailed experimental and computational mechanistic studies provided strong evidence for a facile C-H activation and a rate-determining C-C cleavage, with considerable contribution from London dispersion interactions.

  10. The Copper-nicotinamide complex: sustainable applications in coupling and cycloaddition reactions (United States)

    Crystalline copper (II)-nicotinamide complex, synthesized via simple mixing of copper chloride and nicotinamide solution at room temperature, catalyzes the C-S, C-N bond forming and cycloaddition reactions under a variety of sustainable reaction conditions.

  11. Stereoselectivities in α- and β-Amino Acids Catalyzed Mannich Reactions Involving Cyclohexanone

    Institute of Scientific and Technical Information of China (English)

    WANG Ying; FU Ai-ping; LI Hong-liang; TIAN Feng-hui; YUAN Shu-ping; SI Hong-zong; DUAN Yun-bo; WANG Zong-hua


    The effects of two different amino acid catalysts on the stereoselectivities in the direct Mannich reactions of cyclohexanone,p-anisidine and p-nitrobenzaldehyde were studied with the aid of density functional theory.Transition states of the stereo-determining C-C bond-forming step with the addition of enamine intermediate to the imine for the L-proline(α-amino acid) and (R)-3-pyrrolidinecarboxylic acid(β-amino acid)-catalyzed processes were reported.B3LYP/6-31G** calculations provide a good explanation for the opposite syn vs.anti diastereoselectivities of these two different kinds of catalysts(syn-selectivity for the α-amino acid catalysts,anti-selectivity for the β-amino acid catalysts).Calculated and observed diastereomeric ratio and enantiomeric excess values are in reasonable agreement.

  12. Understanding Rotation about a C=C Double Bond (United States)

    Barrows, Susan E.; Eberlein, Thomas H.


    In this article, twisting about the C=C double bond and the consequential pyramidalization of sp 2 carbon atoms in alkenes were examined in a molecular modeling study using trans -2-butene as a model system. According to our trans -2-butene model and other similar work, most of the strength of a π bond is retained upon twisting, even for remarkably large C C=C C dihedral angles (up to 90°). The phenomenon of sp 2 carbon atom pyramidalization and preservation of π bond strength upon twisting a C=C double bond is well established in the literature, but is rarely discussed in introductory textbooks. This absence is noteworthy because profound manifestations of this effect do occur in compounds that are covered in an introductory organic chemistry curriculum. We present a simple method of introducing the concept of a flexible C=C π bond into beginning organic chemistry courses. We report the energetic demands of partial twisting about the C=C bond in 2-butene as calculated using DFT, LMP2, and MCSCF methods. Finally, using the results of these calculations, we assessed the degree of strain introduced by the twisted nature of the C=C bond in trans cycloalkenes.

  13. Active Brazing of C/C Composite to Copper by AgCuTi Filler Metal (United States)

    Zhang, Kexiang; Xia, Lihong; Zhang, Fuqin; He, Lianlong


    Brazing between the carbon-fiber-reinforced carbon composite (C/C composite) and copper has gained increasing interest because of its important application in thermal management systems in nuclear fusion reactors and in the aerospace industry. In order to examine the "interfacial shape effect" on the mechanical properties of the joint, straight and conical interfacial configurations were designed and machined on the surface of C/C composites before joining to copper using an Ag-68.8Cu-4.5Ti (wt pct) alloy. The microstructure and interfacial microchemistry of C/C composite/AgCuTi/Cu brazed joints were comprehensively investigated by using high-resolution transmission electron microscopy. The results indicate that the joint region of both straight and conical joints can be described as a bilayer. Reaction products of Cu3Ti3O and γ-TiO were formed near the copper side in a conical interface joint, while no reaction products were found in the straight case. The effect of Ag on the interfacial reaction was discussed, and the formation mechanism of the joints during brazing was proposed. On the basis of the detailed microstructure presented, the mechanical performance of the brazed joints was discussed in terms of reaction and morphology across the joint.

  14. Synthesis of Stable Diarylpalladium(II) Complexes: Detailed Study of the Aryl-Aryl Bond-Forming Reductive Elimination. (United States)

    Gensch, Tobias; Richter, Nils; Theumer, Gabriele; Kataeva, Olga; Knölker, Hans-Joachim


    The synthesis of diarylpalladium(II) complexes by twofold aryl C-H bond activation was developed. These intermediates of oxidative cyclization reactions are stabilized by chelation with acetyl groups while still maintaining sufficient reactivity to study their reductive elimination. Four distinct triggers were found for the reductive elimination of these complexes to dibenzofurans and carbazoles. Thermal elimination occurs at very high temperatures, whereas ligand-promoted and oxidatively induced reductive eliminations proceed readily at room temperature. Under these conditions, no isomerization occurs. In contrast, weak Brønsted acids, such as acetic acid, lead to a sequence of proto-demetalation, isomerization to a κ(3) -diarylpalladium(II) complex, and reductive elimination to non-symmetrical cyclization products.

  15. Testing of DLR C/C-SiC and C/C for HIFiRE 8 Scramjet Combustor (United States)

    Glass, David E.; Capriotti, Diego P.; Reimer, Thomas; Kutemeyer, Marius; Smart, Michael K.


    Ceramic Matrix Composites (CMCs) have been proposed for use as lightweight hot structures in scramjet combustors. Previous studies have calculated significant weight savings by utilizing CMCs (active and passive) versus actively cooled metallic scramjet structures. Both a carbon/carbon (C/C) and a carbon/carbon-silicon carbide (C/C-SiC) material fabricated by DLR (Stuttgart, Germany) are being considered for use in a passively cooled combustor design for Hypersonic International Flight Research Experimentation (HIFiRE) 8, a joint Australia / Air Force Research Laboratory hypersonic flight program, expected to fly at Mach 7 for approximately 30 sec, at a dynamic pressure of 55 kilopascals. Flat panels of the DLR C/C and C/C-SiC materials were installed downstream of a hydrogen-fueled, dual-mode scramjet combustor and tested for several minutes at conditions simulating flight at Mach 5 and Mach 6. Gaseous hydrogen fuel was used to fuel the scramjet combustor. The test panels were instrumented with embedded Type K and Type S thermocouples. Zirconia felt insulation was used during some of the tests to reduce heat loss from the back surface and thus increase the heated surface temperature of the C/C-SiC panel approximately 177 C (350 F). The final C/C-SiC panel was tested for three cycles totaling over 135 sec at Mach 6 enthalpy. Slightly more erosion was observed on the C/C panel than the C/C-SiC panels, but both material systems demonstrated acceptable recession performance for the HIFiRE 8 flight.

  16. Tribological characteristics of C/C-SiC braking composites under dry and wet conditions

    Institute of Scientific and Technical Information of China (English)

    LI Zhuan; XIAO Peng; XIONG Xiang; ZHU Su-hua


    C/C-SiC braking composites, based on reinforcement of carbon fibers and rnatrices of carbon and silicon carbide, were fabricated by warm compaction and in situ reaction process. The tribological characteristics of C/C-SiC braking composites under dry and wet conditions were investigated by means of MM-1000 type of friction testing machine. The influence of dry and wet conditions on the tribological characteristics of the C/C-SiC composites was ascertained. Under dry condition, C/C-SiC braking composites show superior tribological characteristics, including high coefficient of friction (0.38), good abrasive resistance (thickness loss is 1.10 μm per cycle) and steady breaking. The main wear mechanism is plastic deformation and abrasion caused by plough. Under wet condition, frictional films form on the worn surface. The coefficient of friction (0.35) could maintain mostly, and the thickness loss (0.70 μm per cycle) reduces to a certain extent. Furthermore, braking curves are steady and adhesion and oxidation are the main wear mechanisms.

  17. Reaction design, discovery, and development as a foundation to function-oriented synthesis. (United States)

    Micalizio, Glenn C; Hale, Sarah B


    Convergent C-C bond-forming reactions define the fabric of organic synthesis and, when applied in complex molecule synthesis, can have a profound impact on efficiency by decreasing the longest linear sequence of transformations required to convert simple starting materials to complex targets. Despite their well-appreciated strategic significance, campaigns in natural product synthesis typically embrace only a small suite of reactivity to achieve such bond construction (i.e., nucleophilic addition to polarized π-bonds, nucleophilic substitution, cycloaddition, and metal-catalyzed "cross-coupling"), therefore limiting the sites at which convergent coupling chemistry can be strategically employed. In our opinion, it is far too often that triumphs in the field are defined by chemical sequences that do not address the challenges associated with discovery, development, and production of natural product-inspired agents. We speculated that advancing an area of chemical reactivity not represented in the few well-established strategies for convergent C-C bond formation may lead to powerful new retrosynthetic relationships that could simplify approaches to the syntheses of a variety of different classes of natural products. Our studies ultimately embraced the pursuit of strategies to control the course of metallacycle-mediated "cross-coupling" between substrates containing sites of simple π-unsaturation (ubiquitous functionality in organic chemistry including alkenes, alkynes, allenes, aldehydes, and imines, among others). In just eight years since our initial publication in this area, we have defined over 20 stereoselective intermolecular C-C bond-forming reactions that provide access to structural motifs of relevance for the synthesis of polyketides, fatty acids, alkaloids, and terpenes, while doing so in a direct and stereoselective fashion. These achievements continue to serve as the foundation of my group's activity in natural product and function-oriented synthesis

  18. Efficient C/C++ programming smaller, faster, better

    CERN Document Server

    Heller, Steve


    Efficient C/C++ Programming describes a practical, real-world approach to efficient C/C++ programming. Topics covered range from how to save storage using a restricted character set and how to speed up access to records by employing hash coding and caching. A selective mailing list system is used to illustrate rapid access to and rearrangement of information selected by criteria specified at runtime.Comprised of eight chapters, this book begins by discussing factors to consider when deciding whether a program needs optimization. In the next chapter, a supermarket price lookup system is used to

  19. Deformation microstructure and orientation of F.C.C. crystals

    DEFF Research Database (Denmark)

    Liu, Q.; Hansen, N.


    The effect of crystallographic orientation on the microstructural evolution in f.c.c. metals with medium to high stacking fault energy is analyzed. This analysis is based on a literature review of the behaviour of single crystals and polycrystals supplemented with an experimental study of cold...

  20. Oxidative electrochemical aryl C-C coupling of spiropyrans

    NARCIS (Netherlands)

    Ivashenko, Oleksii; van Herpt, Jochem T.; Rudolf, Petra; Feringa, Ben L.; Browne, Wesley R.


    The isolation and definitive assignment of the species formed upon electrochemical oxidation of nitro-spiropyran (SP) is reported. The oxidative aryl C-C coupling at the indoline moiety of the SP radical cation to form covalent dimers of the ring-closed SP form is demonstrated. The coupling is block

  1. Get more control over your C/C++ service

    CERN Document Server

    CERN. Geneva


    Are you looking for a way to better diagnose or monitor your C/C++ programs? Find out more about CMX - a neat, lightweight library (<32Kb) which targets this need. It allows to expose information from inside a process through a simple API, enabling pre-failure detection in combination with your favourite monitoring system.

  2. Interstellar detection of c-C3D2

    CERN Document Server

    Spezzano, S; Schilke, P; Caselli, P; Menten, K M; McCarthy, M C; Bizzocchi, L; Trevino-Morales, S P; Aikawa, Y; Schlemmer, S


    We report the first interstellar detection of c-C3D2. The doubly deuterated cyclopropenylidene, a carbene, has been detected toward the starless cores TMC- 1C and L1544 using the IRAM 30m telescope. The J(Ka,Kc) = 3(0,3)-2(1,2), 3(1,3)-2(0,2), and 2(2,1)-1(1,0) transitions of this species have been observed at 3 mm in both sources. The expected 1:2 intensity ratio has been found in the 3(0,3)-2(1,2) and 3(1,3)-2(0,2) lines, belonging to the para and ortho species respectively. We also observed lines of the main species, c-C3H2, the singly deuterated c-C3HD, and the species with one 13C off of the principal axis of the molecule, c-H13CC2H. The lines of c-C3D2 have been observed with high signal to noise ratio, better than 7.5 sigma in TMC-1C and 9 sigma in L1544. The abundance of doubly deuterated cyclopropenylidene with respect to the normal species is found to be (0.4 - 0.8)% in TMC-1C and (1.2 - 2.1)% in L1544. The deuteration of this small hydrocarbon ring is analysed with a comprehensive gas-grain model, ...

  3. Dynamic analysis of C/C composite finger seal

    Institute of Scientific and Technical Information of China (English)

    Chen Guoding; Wang Li’na; Yu Qiangpeng; Su Hua


    A seal device as an important component of aeroengines has decisive influence on per-formance, reliability, and working life of aeroengines. With the development of aeroengines, demands on the performance characteristics of seal devices are made strictly. Finger seal as a novel kind of sealing device, recently attracts more and more attentions in academic circles and engineer-ing fields at home and abroad. Research on finger seals has been extensively developed, especially on leakage and wear performances under dynamic conditions. However, it is a pity that the work on finger seals has been limited with a single approach that is improving the performance by structural optimization;in addition, the technology of dynamic analysis on finger seals is weak. Aiming at the problems mentioned above, a distributed mass equivalent dynamic model of finger seals considering the coupling effect of overlaid laminates is established in the present paper, the dynamic perfor-mance of 2.5 dimension C/C composite finger seal is analyzed with the model, and then the effects of fiber bundle density and fiber bundle preparation direction on finger seal’s dynamic performance are discussed, as well as compared with those of Co-based alloy finger seal. The current work is about dynamic analysis of finger seals and application of C/C composite in this paper may have much academic significance and many engineering values for improving research level of finger seal dynamics and exploring feasibility of C/C composite being used for finger seals.

  4. [Study on spectral emissivity of C/C composites]. (United States)

    Zhu, Bo; Cao, Wei-Wei; Jing, Min; Dong, Xing-Guang; Wang, Cheng-Guo


    Different types of C/C composites were prepared by conventional molding, and the changes in normal spectral emissivity of samples were tested. The testing results show that spectral emissivity of C/C composite reinforced by short cut carbon fibers is generally higher than the sample reinforced by carbon cloth in the entire 2500-13000nm wavelength region. The structure of short cut carbon fibers is relatively loose and the number of material particles is less than other samples in unit volume, which increases the penetration depth of electromagnetic waves. This is the reason for higher normal spectral emissivity and better heat radiation property. Meanwhile, the test results of normal spectral emissivity for fiber perform and C/C composite samples show that the spectral emissivity of resin carbon is better than fiber carbon because of the difference in microstructure for the two kinds of carbon materials. Laser Raman spectroscopy was employed to analyze the microstructures of different carbon materials, and the results show that because sp3 and sp2 hybrid states of carbon atoms in resin carbon produced more vibration modes, the resin carbon also has higher normal spectral emissivity and better characteristics of heat radiation.

  5. Microstructure of C/C Composites with Different Matrix Carbon

    Directory of Open Access Journals (Sweden)

    LIU Hao


    Full Text Available The microstructure of carbon/carbon(C/C composites with different matrix carbon was studied by polarized light microscopy (PLM, scanning electron microscopy (SEM, transmission electron microscopy (TEM and XRD techniques respectively. PLM results indicate that the different matrix carbon exhibits different optical reactivity, and the average optical reactivity is gradually enhanced from normal pitch carbon, smooth laminar of pyrocarbon, rough laminar of pyrocarbon to mesophase pitch carbon; SEM results show that the normal pitch carbon is mainly of grapy structure, the pyrocarbon exhibits like-crinkle lamellar structure, while the mesophase pitch carbon exhibits lamellar banded structure with different shapes. Under HRTEM, the lattice fringes of the mesophase pitch carbon are arranged regularly, is a long range ordered crystal structure, and the preferred orientation is high. The degree of the graphite and the interlayer spacing of the material B (mesophase pitch-based C/C composites are better than that of the material D (pyrocarbon-based C/C composites.

  6. Dynamic analysis of C/C composite finger seal

    Directory of Open Access Journals (Sweden)

    Chen Guoding


    Full Text Available A seal device as an important component of aeroengines has decisive influence on performance, reliability, and working life of aeroengines. With the development of aeroengines, demands on the performance characteristics of seal devices are made strictly. Finger seal as a novel kind of sealing device, recently attracts more and more attentions in academic circles and engineering fields at home and abroad. Research on finger seals has been extensively developed, especially on leakage and wear performances under dynamic conditions. However, it is a pity that the work on finger seals has been limited with a single approach that is improving the performance by structural optimization; in addition, the technology of dynamic analysis on finger seals is weak. Aiming at the problems mentioned above, a distributed mass equivalent dynamic model of finger seals considering the coupling effect of overlaid laminates is established in the present paper, the dynamic performance of 2.5 dimension C/C composite finger seal is analyzed with the model, and then the effects of fiber bundle density and fiber bundle preparation direction on finger seal’s dynamic performance are discussed, as well as compared with those of Co-based alloy finger seal. The current work is about dynamic analysis of finger seals and application of C/C composite in this paper may have much academic significance and many engineering values for improving research level of finger seal dynamics and exploring feasibility of C/C composite being used for finger seals.

  7. A new C=C embedded porphyrin sheet with superior oxygen reduction performance

    Institute of Scientific and Technical Information of China (English)

    Yawei Li[1; Shunhong Zhang[2; Jiabing Yu[1; Qian Wang[2; Qiang Sun[1,2,3; Puru Jena[3


    C2 is a well-known pseudo-oxygen unit with an electron affinity of 3.4 eV. We show that it can exhibit metal-ion like behavior when embedded in a porphyrin sheet and form a metal-free two-dimensional material with superior oxygen reduction performance. Here, the positively charged C=C units are highly active for oxygen reduction reaction (ORR) via dissociation pathways with a small energy barrier of 0.09 eV, much smaller than that of other non-platinum group metal (non-PGM) ORR catalysts. Using a microkinetics-based model we calculated the partial current density to be 3.0 mA/cm2 at 0.65 V vs. a standard hydrogen electrode (SHE), which is comparable to that of the state-of-the-art Pt/C catalyst. We further confirm that the C=C embedded porphyrin sheet is dynamically and thermally stable with a quasi-direct band gap of 1.14 eV. The superior catalytic performance and geometric stability make the metal-free C=C porphyrin sheet ideal for fuel cell applications.

  8. C-C bond formation and related reactions at the CNC backbone in (smif)FeX (smif = 1,3-di-(2-pyridyl)-2-azaallyl): dimerizations, 3 + 2 cyclization, and nucleophilic attack; transfer hydrogenations and alkyne trimerization (X = N(TMS)2, dpma = (di-(2-pyridyl-methyl)-amide)). (United States)

    Frazier, Brenda A; Williams, Valerie A; Wolczanski, Peter T; Bart, Suzanne C; Meyer, Karsten; Cundari, Thomas R; Lobkovsky, Emil B


    Molecular orbital analysis depicts the CNC(nb) backbone of the smif (1,3-di-(2-pyridyl)-2-azaallyl) ligand as having singlet diradical and/or ionic character where electrophilic or nucleophilic attack is plausible. Reversible dimerization of (smif)Fe{N(SiMe3)2} (1) to [{(Me3Si)2N}Fe]2(μ-κ(3),κ(3)-N,py2-smif,smif) (2) may be construed as diradical coupling. A proton transfer within the backbone-methylated, and o-pyridine-methylated smif of putative ((b)Me2(o)Me2smif)FeN(SiMe3)2 (8) provides a route to [{(Me3Si)2N}Fe]2(μ-κ(4),κ(4)-N,py2,C-((b)Me,(b)CH2,(o)Me2(smif)H))2 (9). A 3 + 2 cyclization of ditolyl-acetylene occurs with 1, leading to the dimer [{2,5-di(pyridin-2-yl)-3,4-di-(p-tolyl-2,5-dihydropyrrol-1-ide)}FeN(SiMe3)2]2 (11), and the collateral discovery of alkyne cyclotrimerization led to a brief study that identified Fe(N(SiMe3)2(THF) as an effective catalyst. Nucleophilic attack by (smif)2Fe (13) on (t)BuNCO and (2,6-(i)Pr2C6H3)NCO afforded (RNHCO-smif)2Fe (14a, R = (t)Bu; 14b, 2,6-(i)PrC6H3). Calculations suggested that (dpma)2Fe (15) would favorably lose dihydrogen to afford (smif)2Fe (13). H2-transfer to alkynes, olefins, imines, PhN═NPh, and ketones was explored, but only stoichiometric reactions were affected. Some physical properties of the compounds were examined, and X-ray structural studies on several dinuclear species were conducted.

  9. Organocatalytic Enantioselective Henry Reactions

    Directory of Open Access Journals (Sweden)

    Raquel P. Herrera


    Full Text Available A large number of interesting organocatalytic enantioselective protocols have been explored and successfully applied in the last decade. Among them, the Henry (nitroaldol reaction represents a powerful carbon-carbon bond-forming procedure for the preparation of valuable synthetic intermediates, such as enantioenriched nitro alcohols, which can be further transformed in a number of important nitrogen and oxygen-containing compounds. This area of research is still in expansion and a more complex version of this useful process has recently emerged, the domino Michael/Henry protocol, affording highly functionalized cycles with multiple stereogenic centers.

  10. Measurements of $\\psi(3686) \\to K^{-} \\Lambda \\bar{\\Xi}^{+} +c.c.$ and $\\psi(3686) \\to \\gamma K^{-} \\Lambda \\bar{\\Xi}^{+} +c.c$

    CERN Document Server

    Ablikim, M; Ai, X C; Albayrak, O; Albrecht, M; Ambrose, D J; Amoroso, A; An, F F; An, Q; Bai, J Z; Ferroli, R Baldini; Ban, Y; Bennett, D W; Bennett, J V; Bertani, M; Bettoni, D; Bian, J M; Bianchi, F; Boger, E; Bondarenko, O; Boyko, I; Briere, R A; Cai, H; Cai, X; Cakir, O; Calcaterra, A; Cao, G F; Cetin, S A; Chang, J F; Chelkov, G; Chen, G; Chen, H S; Chen, H Y; Chen, J C; Chen, M L; Chen, S J; Chen, X; Chen, X R; Chen, Y B; Cheng, H P; Chu, X K; Cibinetto, G; Cronin-Hennessy, D; Dai, H L; Dai, J P; Dbeyssi, A; Dedovich, D; Deng, Z Y; Denig, A; Denysenko, I; Destefanis, M; DeMori, F; Ding, Y; Dong, C; Dong, J; Dong, L Y; Dong, M Y; Du, S X; Duan, P F; Fan, J Z; Fang, J; Fang, S S; Fang, X; Fang, Y; Fava, L; Feldbauer, F; Felici, G; Feng, C Q; Fioravanti, E; Fritsch, M; Fu, C D; Gao, Q; Gao, X Y; Gao, Y; Gao, Z; Garzia, I; Geng, C; Goetzen, K; Gong, W X; Gradl, W; Greco, M; Gu, M H; Gu, Y T; Guan, Y H; Guo, A Q; Guo, L B; Guo, Y; Guo, Y P; Haddadi, Z; Hafner, A; Han, S; Han, Y L; Hao, X Q; Harris, F A; He, K L; He, Z Y; Held, T; Heng, Y K; Hou, Z L; Hu, C; Hu, H M; Hu, J F; Hu, T; Hu, Y; Huang, G M; Huang, G S; Huang, H P; Huang, J S; Huang, X T; Huang, Y; Hussain, T; Ji, Q; Ji, Q P; Ji, X B; Ji, X L; Jiang, L L; Jiang, L W; Jiang, X S; Jiao, J B; Jiao, Z; Jin, D P; Jin, S; Johansson, T; Julin, A; Kalantar-Nayestanaki, N; Kang, X L; Kang, X S; Kavatsyuk, M; Ke, B C; Kliemt, R; Kloss, B; Kolcu, O B; Kopf, B; Kornicer, M; Kühn, W; Kupsc, A; Lai, W; Lange, J S; Lara, M; Larin, P; Leng, C; Li, C H; Li, Cheng; Li, D M; Li, F; Li, G; Li, H B; Li, J C; Li, Jin; Li, K; Li, Lei; Li, P R; Li, T; Li, W D; Li, W G; Li, X L; Li, X M; Li, X N; Li, X Q; Li, Z B; Liang, H; Liang, Y F; Liang, Y T; Liao, G R; Lin, D X; Liu, B J; Liu, C X; Liu, F H; Liu, Fang; Liu, Feng; Liu, H B; Liu, H H; Liu, H M; Liu, J; Liu, J P; Liu, J Y; Liu, K; Liu, K Y; Liu, L D; Liu, P L; Liu, Q; Liu, S B; Liu, X; Liu, X X; Liu, Y B; Liu, Z A; Liu, Zhiqiang; Liu, Zhiqing; Loehner, H; Lou, X C; Lu, H J; Lu, J G; Lu, R Q; Lu, Y; Lu, Y P; Luo, C L; Luo, M X; Luo, T; Luo, X L; Lv, M; Lyu, X R; Ma, F C; Ma, H L; Ma, L L; Ma, Q M; Ma, S; Ma, T; Ma, X N; Ma, X Y; Maas, F E; Maggiora, M; Malik, Q A; Mao, Y J; Mao, Z P; Marcello, S; Messchendorp, J G; Min, J; Min, T J; Mitchell, R E; Mo, X H; Mo, Y J; Morales, C Morales; Moriya, K; Muchnoi, N Yu; Muramatsu, H; Nefedov, Y; Nerling, F; Nikolaev, I B; Ning, Z; Nisar, S; Niu, S L; Niu, X Y; Olsen, S L; Ouyang, Q; Pacetti, S; Patteri, P; Pelizaeus, M; Peng, H P; Peters, K; Pettersson, J; Ping, J L; Ping, R G; Poling, R; Pu, Y N; Qi, M; Qian, S; Qiao, C F; Qin, L Q; Qin, N; Qin, X S; Qin, Y; Qin, Z H; Qiu, J F; Rashid, K H; Redmer, C F; Ren, H L; Ripka, M; Rong, G; Ruan, X D; Santoro, V; Sarantsev, A; Savrié, M; Schoenning, K; Schumann, S; Shan, W; Shao, M; Shen, C P; Shen, P X; Shen, X Y; Sheng, H Y; Song, W M; Song, X Y; Sosio, S; Spataro, S; Sun, G X; Sun, J F; Sun, S S; Sun, Y J; Sun, Y Z; Sun, Z J; Sun, Z T; Tang, C J; Tang, X; Tapan, I; Thorndike, E H; Tiemens, M; Toth, D; Ullrich, M; Uman, I; Varner, G S; Wang, B; Wang, B L; Wang, D; Wang, D Y; Wang, K; Wang, L L; Wang, L S; Wang, M; Wang, P; Wang, P L; Wang, Q J; Wang, S G; Wang, W; Wang, X F; Wang, Y D; Wang, Y F; Wang, Y Q; Wang, Z; Wang, Z G; Wang, Z H; Wang, Z Y; Weber, T; Wei, D H; Wei, J B; Weidenkaff, P; Wen, S P; Wiedner, U; Wolke, M; Wu, L H; Wu, Z; Xia, L G; Xia, Y; Xiao, D; Xiao, Z J; Xie, Y G; Xiu, Q L; Xu, G F; Xu, L; Xu, Q J; Xu, Q N; Xu, X P; Yan, L; Yan, W B; Yan, W C; Yan, Y H; Yang, H X; Yang, L; Yang, Y; Yang, Y X; Ye, H; Ye, M; Ye, M H; Yin, J H; Yu, B X; Yu, C X; Yu, H W; Yu, J S; Yuan, C Z; Yuan, W L; Yuan, Y; Yuncu, A; Zafar, A A; Zallo, A; Zeng, Y; Zhang, B X; Zhang, B Y; Zhang, C; Zhang, C C; Zhang, D H; Zhang, H H; Zhang, H Y; Zhang, J J; Zhang, J L; Zhang, J Q; Zhang, J W; Zhang, J Y; Zhang, J Z; Zhang, K; Zhang, L; Zhang, S H; Zhang, X Y; Zhang, Y; Zhang, Y H; Zhang, Y T; Zhang, Z H; Zhang, Z P; Zhang, Z Y; Zhao, G; Zhao, J W; Zhao, J Y; Zhao, J Z; Zhao, Lei; Zhao, Ling; Zhao, M G; Zhao, Q; Zhao, Q W; Zhao, S J; Zhao, T C; Zhao, Y B; Zhao, Z G; Zhemchugov, A; Zheng, B; Zheng, J P; Zheng, W J; Zheng, Y H; Zhong, B; Zhou, L; Zhou, Li; Zhou, X; Zhou, X K; Zhou, X R; Zhou, X Y; Zhu, K; Zhu, K J; Zhu, S; Zhu, X L; Zhu, Y C; Zhu, Y S; Zhu, Z A; Zhuang, J; Zotti, L; Zou, B S; Zou, J H


    Using a sample of $1.06\\times10^8\\ \\psip$ events produced in $e^+e^-$ collisions at $\\sqrt{s}$ = 3.686 GeV and collected with the BESIII detector at the BEPCII collider, we present studies of the decays $\\klx+c.c.$ and $\\gklx+c.c.$. We observe two hyperons, $\\Xi(1690)^-$ and $\\Xi(1820)^-$, in the $K^-\\Lambda$ invariant mass distribution in the decay $\\klx+c.c.$ with significances of $4.9 \\sigma$ and $6.2 \\sigma$, respectively. The branching fractions of $\\klx+c.c.$, $\\ksx+c.c.$, $\\psip\\to\\gamma \\chi_{cJ}\\to \\gamma K^- \\Lambda \\bar{\\Xi}^+ +c.c.$ $(J=0,\\ 1,\\ 2)$, and $\\psip\\to \\Xi(1690/1820)^{-} \\bar{\\Xi}^++c.c$ with subsequent decay $\\Xi(1690/1820)^-\\to K^-\\Lambda$ are measured for the first time.

  11. Asymmetric Michael Reaction of Malononitrile Catalyzed by Chiral Ru(Ⅱ) Complex and Achiral Base

    Institute of Scientific and Technical Information of China (English)

    MA Ya-Ping; XING Zhi-Kui; ZHU Jin; CUI Xin; CUN Lin-Feng; DENG Jin-Gen


    @@ Michael addition reactions represent one of the most important carbon-carbon bond forming reactions in modern synthetic organic chemistry. [1 ~3] We achieved catalytic enantioselective Michael addition reactions of malononitrile with chiral vicinal diamine-Ru(Ⅱ) complex in the presence of achiral base. High yields and moderate ee were observed.

  12. Mirrors fabricated with slightly oxidized C/C composites (United States)

    Wang, Yongjie; Xu, Liang; Ding, Jiaoteng; Xie, Yongjie; Ma, Zhen


    Up to now, traditional materials, such as glass, metal and SiC ceramic, gradually begin to be unsatisfied development of the future mirrors. Designable carbon fiber reinforced composites became optimized material for large aperture lightweight mirrors. Carbon/carbon composites exhibit low thermal expansion and no moisture-absorption expansion problem, therefore, they get particular attention in the space reflector field. Ni was always employed as optical layer in the mirror, however, the coating behaved poor bond with substrate and often peeled off during optical processing. In order to solve this problem, slight oxidation was carried on the C/C composites before Ni plated. The Ni coating exhibited stronger coherence and better finish performance. Finally, a 100mm diameter plane mirror was successful fabricated.

  13. Microstructure characteristic and formation mechanism of crackfree TaC coating on C/C composite

    Institute of Scientific and Technical Information of China (English)

    LI Guo-dong; XIONG Xiang; HUANG Bai-yun


    The microstructure characteristic and formation mechanism of the crackfree and ablation-resistant TaC coating deposited on the C/C composite by Chemical Vapour Deposition(CVD) were investigated, using the reaction system of TaCl5-C3H6-H2-Ar. The results show that the nanosized pore structure formed in the TaC coating interior during CVD process is the main factor to reduce the hardness, elastic modulus, linear expansibility and inner thermal stress. Then crackfree coatings can be prepared and their thermal shock resistance can be enhanced. To obtain the dense and homogeneous matrix surface is necessary for the crackfree and low stress coating. The TaC coating structure that distributes from the dense matrix towards loose coating surface will result in the thick crackfree coating with good thermal shock resistance.

  14. Anti-oxidation mechanism of SiC-B4C-C composites

    Institute of Scientific and Technical Information of China (English)

    LIU Qi-cheng; XU Xie-wen; HUANG Qi-zhong; HUANG Bai-yun


    Mixture of green petroleum coke, B4C and SiC together with short carbon fiber were employed as starting materials, the mixture was press-formed without any binder after grinding, dense and homogeneous binderless SiC-B4C-C(carbon/ceramic) composites were then obtained after sintering. Composites thus prepared possess excellent anti-oxidation property, that is, mass loss less than 1% within the temperature range from 900 to 1100℃ for 10h. Anti-oxidation mechanism was also discussed from the viewpoint of thermodynamics, excellent anti-oxidation property of materials thus prepared can be discribed to 1) solid SiO2 formed from SiC, which restrains the filtering of oxygen and simultaneously, its volume expansion brought about by the reaction takes roles both walling up the original pores and making the material more compact; 2) liquid B2O3 from the reaction of B4C not only makes the combination with C, B4C and SiC tighter through forming solid solution, but also effect of reaction SiC(s)+2CO(g)=SiO2(s)+3C(s) is an expansive process, which improves the microstructure of the material.

  15. Carbonyl-Olefin Exchange Reaction and Related Chemistry (United States)

    Jossifov, Christo; Kalinova, Radostina

    A new carbon—carbon double bond forming reaction (carbonyl olefin exchange reaction) mediated by transition metal catalytic systems has been discovered. The catalytic systems used (transition metal halides or oxohalides alone or in combination with Lewis acids) are active only in the case when the two reacting groups are in one molecules and are conjugated. In addition these systems accelerate other reactions which run simultaneously with the carbonyl olefin metathesis rendering a detailed investigation of the process very complicated.

  16. C/C++预处理分析与改进%Improvement on C/C++ Preprocessor

    Institute of Scientific and Technical Information of China (English)




  17. Oxidation Behavior of C/C-SiC Gradient Matrix Composites

    Institute of Scientific and Technical Information of China (English)


    Oxidation behavior of C/C-SiC gradient matrix composites and C/C composites were compared in stationary air. The results show that oxidation threshold of C-SiC materials increases with the amount of SiC particles in the codeposition matrix. Oxidation rate of C/C-SiC gradient matrix composites is significantly lower than that of C/C material. The micro-oxidation process was observed by SEM.

  18. Determinación teórica de parámetros estructurales: Estudio de los isómeros [Al,C,C,C] y [Al,C,C,Si


    García Vivas, María Esmeralda


    Se ha llevado a cabo un estudio teórico-computacional sobre distintos isómeros [Al,C,C,C] y [Al,C,C,Si]. El estudio se ha realizado dentro del contexto de la Teoría del Funcional de la Densidad (DFT) empleando el funcional B3LYP y la base aug-cc-pVTZ. Para cada uno de los sistemas estudiados hemos caracterizado estructuras lineales (o cuasilineales), cíclicas bien romboidales o de tipo “fan” y estructuras que contienen un anillo de tres miembros. Además se ha llevado a cabo un análisi d...

  19. The Novel Selective Reduction of the C-C Triple Bond

    Institute of Scientific and Technical Information of China (English)


    A novel reduction system is reported here in which the compounds with terminal C-C triple bond and disubstituted C-C triple bond react with NaBH4/Pd(PPh3)4 in a base condition and only terminal C-C triple bond is reduced.

  20. A mild route to mesoporous Mo2C-C hybrid nanospheres for high performance lithium-ion batteries (United States)

    Gao, Qing; Zhao, Xinyu; Xiao, Ying; Zhao, Di; Cao, Minhua


    In this work, we have developed a mild route to fabricate typically mesoporous Mo2C-C hybrid nanospheres based on a solvothermal synthesis and reduction-carbonization process. This work opens a low-temperature route to synthesize valuable carbides. The resultant Mo2C-C hybrid, for the first time, is used as an anode material in lithium ion batteries (LIBs). Compared with bulk Mo2C, the Mo2C-C hybrid exhibits much better electrochemical performance. Remarkably, the hybrid electrode can deliver a specific capacity of over 670 mA h g-1 after 50 cycles at 100 mA g-1, which is much higher than that of the bulk material (113 mA h g-1). Even cycled at a high current density of 1000 mA g-1, high capacities of around 400-470 mA h g-1 can still be retained for the Mo2C-C hybrid. It might benefit from the synergistic effect of the nanohybridization, effectively relieving the volume change during the repeated lithium insertion-extraction reactions and maintaining the integrity of the electrical connections. It is expected that the present synthesis strategy for the Mo2C-C hybrid can be extended to other nanostructured carbides with good energy storage performance.In this work, we have developed a mild route to fabricate typically mesoporous Mo2C-C hybrid nanospheres based on a solvothermal synthesis and reduction-carbonization process. This work opens a low-temperature route to synthesize valuable carbides. The resultant Mo2C-C hybrid, for the first time, is used as an anode material in lithium ion batteries (LIBs). Compared with bulk Mo2C, the Mo2C-C hybrid exhibits much better electrochemical performance. Remarkably, the hybrid electrode can deliver a specific capacity of over 670 mA h g-1 after 50 cycles at 100 mA g-1, which is much higher than that of the bulk material (113 mA h g-1). Even cycled at a high current density of 1000 mA g-1, high capacities of around 400-470 mA h g-1 can still be retained for the Mo2C-C hybrid. It might benefit from the synergistic effect of

  1. Synthesis of 2,1-benzisoxazole-3(1H)-ones by base-mediated photochemical N–O bond-forming cyclization of 2-azidobenzoic acids (United States)

    Dzhons, Daria Yu


    Summary The base-mediated photochemical cyclization of 2-azidobenzoic acids with the formation of 2,1-benzisoxazole-3(1H)-ones is reported. The optimization and scope of this cyclization reaction is discussed. It is shown that an essential step of the ring closure of 2-azidobenzoic acids is the formation and photolysis of 2-azidobenzoate anions. PMID:27340478

  2. Stereochemistry of enzymatic water addition to C=C bonds. (United States)

    Chen, Bi-Shuang; Otten, Linda G; Hanefeld, Ulf


    Water addition to carbon-carbon double bonds using hydratases is attracting great interest in biochemistry. Most of the known hydratases are involved in primary metabolism and to a lesser extent in secondary metabolism. New hydratases have recently been added to the toolbox, both from natural sources or artificial metalloenzymes. In order to comprehensively understand how the hydratases are able to catalyse the water addition to carbon-carbon double bonds, this review will highlight the mechanistic and stereochemical studies of the enzymatic water addition to carbon-carbon double bonds, focusing on the syn/anti-addition and stereochemistry of the reaction.

  3. Aliphatic C-C Bond Cleavage in α-Hydroxy Ketones by a Dioxygen-Derived Nucleophilic Iron-Oxygen Oxidant. (United States)

    Bhattacharya, Shrabanti; Rahaman, Rubina; Chatterjee, Sayanti; Paine, Tapan K


    A nucleophilic iron-oxygen oxidant, formed in situ in the reaction between an iron(II)-benzilate complex and O2 , oxidatively cleaves the aliphatic C-C bonds of α-hydroxy ketones. In the cleavage reaction, α-hydroxy ketones without any α-C-H bond afford a 1:1 mixture of carboxylic acid and ketone. Isotope labeling studies established that one of the oxygen atoms from dioxygen is incorporated into the carboxylic acid product. Furthermore, the iron(II) complex cleaves an aliphatic C-C bond of 17-α-hydroxyprogesterone affording androstenedione and acetic acid. The O2 -dependent aliphatic C-C bond cleavage of α-hydroxy ketones containing no α-C-H bond bears similarity to the lyase activity of the heme enzyme, cytochrome P450 17A1 (CYP17A1).

  4. Bicyclic proline analogues as organocatalysts for stereoselective aldol reactions: an in silico DFT study. (United States)

    Shinisha, C B; Sunoj, Raghavan B


    Density functional theory has been employed in investigating the efficiency of a series of bicyclic analogues of proline as stereoselective organocatalysts for the aldol reaction. Three classes of conformationally restricted proline analogues, as part of either a [2.2.1] or [2.1.1] bicyclic framework, have been studied. Transition states for the stereoselective C-C bond formation between enamines derived from [2.2.1] and [2.1.1] bicyclic amino acids and p-nitrobenzaldehyde, leading to enantiomeric products, have been identified. Analysis of the transition state geometries revealed that the structural rigidity of catalysts, improved transition state organization as well as other weak interactions influence the relative stabilities of diastereomeric transition states and help contribute to the overall stereoselectivity in the aldol reaction. These bicyclic catalysts are predicted to be substantially more effective in improving the enantiomeric excess than the widely used organocatalyst proline. Enantiomeric excesses in the range 82-95% are predicted for these bicyclic catalysts when a sterically unbiased substrate such as p-nitrobenzaldehyde is employed for the asymmetric aldol reaction. More interestingly, introduction of substituents, as simple as a methyl group, at the ortho position of the aryl aldehyde bring about an increase in the enantiomeric excess to values greater than 98%. The reasons behind the vital energy separation between diastereomeric transition states has been rationalized with the help of a number of weak interactions such as intramolecular hydrogen bonding and Coulombic interactions operating on the transition states. These predictions could have wider implications for the rational design of improved organocatalysts for stereoselective carbon-carbon bond-forming reactions.

  5. Recent advances in N-heterocyclic carbene (NHC-catalysed benzoin reactions

    Directory of Open Access Journals (Sweden)

    Rajeev S. Menon


    Full Text Available N-Heterocyclic carbenes (NHCs have emerged as a powerful class of organocatalysts that mediate a variety of organic transformations. The Benzoin reaction constitutes one of the earliest known carbon–carbon bond-forming reactions catalysed by NHCs. The rapid growth of NHC catalysis in general has resulted in the development of a variety of benzoin and benzoin-type reactions. An overview of such NHC-catalysed benzoin reactions is presented.

  6. Thermoelectric properties of SiC/C composites from wood charcoal by pulse current sintering

    NARCIS (Netherlands)

    Fujisawa, M; Hata, T; Bronsveld, P; Castro, [No Value; Tanaka, F; Kikuchi, H; Imamura, Y


    SiC/C composites were investigated by sintering a mix of wood charcoal and SiO2 powder (32-45 mu m) at 1400, 1600 and 1800 degrees C under N-2 atmosphere with a pulse current sintering method. Thermoelectric properties of SiC/C composites were investigated by measuring the Seebeck coefficient and th

  7. 76 FR 44800 - Election of Reduced Research Credit Under Section 280C(c)(3) (United States)


    ... [TD 9539] RIN 1545-BI09 Election of Reduced Research Credit Under Section 280C(c)(3) AGENCY: Internal... dates of applicability, see Sec. 1.280C- 4(c). FOR FURTHER INFORMATION CONTACT: David Selig, (202) 622... research credit under section 280C(c)(3). On July 16, 2009, a notice of proposed rulemaking...

  8. Ablation Resistance of C/C Composites with Atmospheric Plasma-Sprayed W Coating (United States)

    Zhou, Zhe; Wang, Yuan; Gong, Jieming; Ge, Yicheng; Peng, Ke; Ran, Liping; Yi, Maozhong


    To improve the ablation resistance of carbon/carbon (C/C) composites, tungsten (W) coating with thickness of 1.2 mm was applied by atmospheric plasma spraying. The antiablation property of the coated composites was evaluated by oxyacetylene flame ablation experiments. The phase composition of the coating was investigated by a combination of x-ray diffraction analysis and scanning electron microscopy with energy-dispersive x-ray spectroscopy analysis. The ablation resistance of the coated C/C substrates was compared with that of uncoated C/C composites and C/C-CuZr composites after ablation for 30 s. The properties of the coated C/C composites after ablation time of 10, 30, 60, 90, 120, and 180 s were further studied. The results indicated that the mass and linear ablation rates of the W-coated C/C composites were lower than those of uncoated C/C or C/C-CuZr composites after ablation for 30 s. The coating exhibited heat stability after 120 s of ablation, with mass loss and linear ablation rates of 7.39 × 10-3 g/s and 3.50 × 10-3 mm/s, respectively. However, the W coating became ineffective and failed after ablation for 180 s. Three ablation regions could be identified, in which the ablation mechanism of the coating changed from thermochemical to thermophysical erosion to mechanical scouring with increasing ablation time.

  9. Proton stopping in C+C, d+C, C+Ta and d+Ta collisions at 4.2A GeV/c

    CERN Document Server

    Simic, L; Simic, Lj.


    The shape of proton rapidity distributions is analysed in terms of their Gaussian components, and the average rapidity loss is determined in order to estimate the amount of stopping in C+C, d+C, C+Ta and d+Ta collisions at 4.2A GeV/c. Three Gaussians correspond to the nuclear transparency and describe well all peripheral and also C+C central collisions. Two-component shape is obtained in case of d+C and C+Ta central collisions. Finally one Gaussian, found in d+Ta central collisions, corresponds to the full stopping. The calculated values of the average rapidity loss support the qualitative relationship between the number of Gaussian components and the corresponding stopping power. It is also observed, in central collisions, that the average rapidity loss increases with the ratio of the number of target and the number of projectile participants.

  10. Computational exploration of the reaction mechanism of the Cu(+)-catalysed synthesis of indoles from N-aryl enaminones. (United States)

    Bernardo, Carlos E P; Silva, Pedro J


    We have studied the role of Cu(+)-phenantroline as a catalyst in the cyclization of N-aryl-enaminones using density-functional theory computations. The catalyst was found to bind the substrate upon deprotonation of its eneaminone, and to dramatically increase the acidity of the carbon adjacent to the ketone functionality. The deprotonation of this carbon atom yields a carbanion which attacks the aryl moiety, thereby closing the heterocycle in the rate-determining step. This C-C bond forming reaction was found to proceed much more rapidly when preceded by re-protonation of the substrate N-atom (which had lost H(+) in the initial step). Hydride transfer to the catalyst then completes the indole synthesis, in a very fast step. The influence of Li(+) and K(+) on the regio-selectivity of the cyclization of bromo-substituted analogues could not, however, be reproduced by our model. Alternative pathways involving either single-electron transfer from the catalyst to the substrate or ring cyclization without previous carbon α-deprotonation were found to be kinetically or thermodynamically inaccessible.

  11. Bioinspired Syntheses of Dimeric Hydroxycinnamic Acids (Lignans and Hybrids, Using Phenol Oxidative Coupling as Key Reaction, and Medicinal Significance Thereof

    Directory of Open Access Journals (Sweden)

    George E. Magoulas


    Full Text Available Lignans are mainly dimers of 4-hydroxycinnamic acids (HCAs and reduced analogs thereof which are produced in Nature through phenol oxidative coupling (POC as the primary C-C or C-O bond-forming reaction under the action of the enzymes peroxidases and laccases. They present a large structural variety and particularly interesting biological activities, therefore, significant efforts has been devoted to the development of efficient methodologies for the synthesis of lignans isolated from natural sources, analogs and hybrids with other biologically interesting small molecules. We summarize in the present review those methods which mimic Nature for the assembly of the most common lignan skeleta by using either enzymes or one-electron inorganic oxidants to effect POC of HCAs and derivatives, such as esters and amides, or cross-POC of pairs of HCAs or HCAs with 4-hydrocycinnamyl alcohols. We, furthermore, provide outlines of mechanistic schemes accounting for the formation of the coupled products and, where applicable, indicate their potential application in medicine.

  12. 在MATLAB环境下创建C/C++外部应用程序的方法%The Method of Establishing C/C++ Exterior Application under MATLAB

    Institute of Scientific and Technical Information of China (English)




  13. An excursion from normal to inverted C-C bonds shows a clear demarcation between covalent and charge-shift C-C bonds. (United States)

    Shaik, Sason; Chen, Zhenhua; Wu, Wei; Stanger, Amnon; Danovich, David; Hiberty, Philippe C


    What is the nature of the C-C bond? Valence bond and electron density computations of 16 C-C bonds show two families of bonds that flesh out as a phase diagram. One family, involving ethane, cyclopropane and so forth, is typified by covalent C-C bonding wherein covalent spin-pairing accounts for most of the bond energy. The second family includes the inverted bridgehead bonds of small propellanes, where the bond is neither covalent nor ionic, but owes its existence to the resonance stabilization between the respective structures; hence a charge-shift (CS) bond. The dual family also emerges from calculated and experimental electron density properties. Covalent C-C bonds are characterized by negative Laplacians of the density, whereas CS-bonds display small or positive Laplacians. The positive Laplacian defines a region suffering from neighbouring repulsive interactions, which is precisely the case in the inverted bonding region. Such regions are rich in kinetic energy, and indeed the energy-density analysis reveals that CS-bonds are richer in kinetic energy than the covalent C-C bonds. The large covalent-ionic resonance energy is precisely the mechanism that lowers the kinetic energy in the bonding region and restores equilibrium bonding. Thus, different degrees of repulsive strain create two bonding families of the same chemical bond made from a single atomic constituent. It is further shown that the idea of repulsive strain is portable and can predict the properties of propellanes of various sizes and different wing substituents. Experimentally (M. Messerschmidt, S. Scheins, L. Bruberth, M. Patzel, G. Szeimies, C. Paulman, P. Luger, Angew. Chem. 2005, 117, 3993-3997; Angew. Chem. Int. Ed. 2005, 44, 3925-3928), the C-C bond families are beautifully represented in [1.1.1]propellane, where the inverted C-C is a CS-bond, while the wings are made from covalent C-C bonds. What other manifestations can we expect from CS-bonds? Answers from experiment have the potential

  14. Thermodynamic and kinetic studies of the equilibration reaction between the sulfur and carbon bonded forms of a cobalt(III) complex with the ligands 1,4,7-triazycyclononane and 1,4-diaza-7-thiacyclodecane

    DEFF Research Database (Denmark)

    Song, Y.S.; Becker, J.; Kofod, Pauli


    -sulfur complex to form the alkyl complex gave 100% loss of deuterium. It is concluded that the labile methylene proton is bound to the carbon atom which in the alkyl complex is bound to cobalt(III). From the kinetic data it is estd. that the carbanion reacts with water 270 times faster than it is captured......The new cyclic thioether 1,4-diaza-7-thiacyclodecane, dathicd, has been synthesized and used for the prepn. of the sulfur- and carbon-bonded cobalt(III) complexes: [Co(tacn)(S-dathicd)]Cl3.5H2O and [Co(tacn)(C-dathicd)](ClO4)2 (tacn, 1,4,7-triazacyclononane; C-dathicd, 1,4-diamino-7-thiacyclodecan...

  15. Thermodynamic and kinetic studies of the equilibration reaction between the sulfur and carbon bonded forms of a cobalt(III) complex with the ligands 2-aminoethyl-3-aminopropylsulfide and 1,1,1-tris(aminomethyl)ethane

    DEFF Research Database (Denmark)

    Springborg, J.; Kjellerup, S.; Kofod, Pauli


    A thermodn. and kinetic study of the equilibration between the Co-S bonded complex Co(tame)(S-aeaps)3+ and the Co-C bonded complex Co(tame)(C-aeaps)2+ is reported (tame = 1,1,1-tris(aminomethyl)ethane, aeaps = 2-aminoethyl-3-aminopropyl sulfide = 3-thiahexane-1,6-diamine and C-aeaps = 1,6-diamine-3...

  16. Preparation and use of samarium diiodide (SmI(2)) in organic synthesis: the mechanistic role of HMPA and Ni(II) salts in the samarium Barbier reaction. (United States)

    Sadasivam, Dhandapani V; Choquette, Kimberly A; Flowers, Robert A


    Although initially considered an esoteric reagent, SmI(2) has become a common tool for synthetic organic chemists. SmI(2) is generated through the addition of molecular iodine to samarium metal in THF.(1,2-3) It is a mild and selective single electron reductant and its versatility is a result of its ability to initiate a wide range of reductions including C-C bond-forming and cascade or sequential reactions. SmI(2) can reduce a variety of functional groups including sulfoxides and sulfones, phosphine oxides, epoxides, alkyl and aryl halides, carbonyls, and conjugated double bonds.(2-12) One of the fascinating features of SmI-(2)-mediated reactions is the ability to manipulate the outcome of reactions through the selective use of cosolvents or additives. In most instances, additives are essential in controlling the rate of reduction and the chemo- or stereoselectivity of reactions.(13-14) Additives commonly utilized to fine tune the reactivity of SmI(2) can be classified into three major groups: (1) Lewis bases (HMPA, other electron-donor ligands, chelating ethers, etc.), (2) proton sources (alcohols, water etc.), and (3) inorganic additives (Ni(acac)(2), FeCl(3), etc).(3) Understanding the mechanism of SmI(2) reactions and the role of the additives enables utilization of the full potential of the reagent in organic synthesis. The Sm-Barbier reaction is chosen to illustrate the synthetic importance and mechanistic role of two common additives: HMPA and Ni(II) in this reaction. The Sm-Barbier reaction is similar to the traditional Grignard reaction with the only difference being that the alkyl halide, carbonyl, and Sm reductant are mixed simultaneously in one pot.(1,15) Examples of Sm-mediated Barbier reactions with a range of coupling partners have been reported,(1,3,7,10,12) and have been utilized in key steps of the synthesis of large natural products.(16,17) Previous studies on the effect of additives on SmI(2) reactions have shown that HMPA enhances the

  17. Effects of Hydrogen Ion Implantation on TiC-C Coating of Stainless Steel

    Institute of Scientific and Technical Information of China (English)

    ZHANG Rui-qian; LIU Yao-guang; HUANG Ning-kang


    Titanium carbide coatings are widely used as various wear-resistant material.The hydrogen erosion resistance of TiC-C films and the effect of hydrogen participation on TiC-C films were studied.Seventy-five percent TiC-C films are prepared on stainless steel surface by using ion mixing,where TiC-C films are deposited by rf magnetron sputtering followed by argon ion bombardment.The samples are then submitted to hydrogen ion implantation at 1.2×10-3 Pa.Characterization for the 75% TiC-C films was done with SIMS,XRD,AES,and XPS.Secondary ion mass spectroscopy (SIMS) was used to analyze hydrogen concentration variation with depth,X-Ray diffraction (XRD) was used to identify the phases,and Auger electron spectra (AES) as well as X-ray photoelectron spectra (XPS) were used to check the effects of hydrogen on shifts of chemical bonding states of C and Ti in the TiC-C films.It is found that TiC-C films on stainless steel surface can prevent hydrogen from entering stainless steel.

  18. Synthesis of Quinoxaline Derivatives via Tandem Oxidative Azidation/Cyclization Reaction of N-Arylenamines. (United States)

    Ma, Haichao; Li, Dianjun; Yu, Wei


    A new method was developed for the synthesis of quinoxalines. This method employs N-arylenamines and TMSN3 as the starting materials and implements two oxidative C-N bond-forming processes in a tandem pattern by using (diacetoxyiodo)benzene as the common oxidant. The present reaction conditions are mild and simple and thus are useful in practical synthesis.

  19. Electron attachment properties of c-C4F8O in different environments (United States)

    Chachereau, A.; Fedor, J.; Janečková, R.; Kočišek, J.; Rabie, M.; Franck, C. M.


    The electron attachment properties of octafluorotetrahydrofuran (c-C4F8O) are investigated using two complementary experimental setups. The attachment and ionization cross sections of c-C4F8O are measured using an electron beam experiment. The effective ionization rate coefficient, electron drift velocity and electron diffusion coefficient in c-C4F8O diluted to concentrations lower than 0.6% in the buffer gases N2, CO2 and Ar, are measured using a pulsed Townsend experiment. A kinetic model is proposed, which combines the results of the two experiments.

  20. Mathematical Simulation of Graphene With Modified c-c Bond Length and Transfer Energy

    Directory of Open Access Journals (Sweden)

    P.A. Alvi


    Full Text Available In nanotechnology research, allotropes of carbon like Graphene, Fullerene (Buckyball and Carbon nanotubes are widely used due to their remarkable properties. Electrical and mechanical properties of those allotropes vary with their molecular geometry. This paper is specially based on modeling and simulation of graphene in order to calculate energy band structure in k space with varying the C-C bond length and C-C transfer energy. Significant changes have been observed in the energy band structure of graphene due to variation in C-C bond length and C-C transfer energy. In particular, this paper focuses over the electronic structure of graphene within the frame work of tight binding approximation. It has been reported that conduction and valence states in graphene only meet at two points in k-space and that dispersion around these special points is conical.

  1. Observation of the decay $\\psi(3686)$ $\\rightarrow$ $\\Lambda\\bar\\Sigma^{\\pm}\\pi^{\\mp}+c.c.$

    CERN Document Server

    Ablikim, M; Ai, X C; Albayrak, O; Ambrose, D J; An, F F; An, Q; Bai, J Z; A, R Baldini Ferroli; Ban, Y; Bennett, J V; A, M Bertani; Bian, J M; Boger, E; Bondarenko, O; Boyko, I; Braun, S; Briere, R A; Cai, H; Cai, X; A, O Cakir; A, A Calcaterra; Cao, G F; B, S A Cetin; Chang, J F; Chelkov, G; Chen, G; Chen, H S; Chen, J C; Chen, M L; Chen, S J; Chen, X; Chen, X R; Chen, Y B; Cheng, H P; Chu, X K; Chu, Y P; Cronin-Hennessy, D; Dai, H L; Dai, J P; Dedovich, D; Deng, Z Y; Denig, A; Denysenko, I; Destefanis, M; Ding, W M; Ding, Y; Dong, C; Dong, J; Dong, L Y; Dong, M Y; Du, S X; Fang, J; Fang, S S; Fang, Y; Fava, L; Feng, C Q; Fu, C D; Fu, J L; Fuks, O; Gao, Q; Gao, Y; Geng, C; Goetzen, K; Gong, W X; Gradl, W; Greco, M; Gu, M H; Gu, Y T; Guan, Y H; Guo, A Q; Guo, L B; Guo, T; Guo, Y P; Han, Y L; Harris, F A; He, K L; He, M; He, Z Y; Held, T; Heng, Y K; Hou, Z L; Hu, C; Hu, H M; Hu, J F; Hu, T; Huang, G M; Huang, G S; Huang, J S; Huang, L; Huang, X T; Hussain, T; Ji, C S; Ji, Q; Ji, Q P; Ji, X B; Ji, X L; Jiang, L L; Jiang, X S; Jiao, J B; Jiao, Z; Jin, D P; Jin, S; Jing, F F; Johansson, T; Kalantar-Nayestanaki, N; Kang, X L; Kavatsyuk, M; Kloss, B; Kopf, B; Kornicer, M; Kuehn, W; Kupsc, A; Lai, W; Lange, J S; Lara, M; Larin, P; Leyhe, M; Li, C H; Li, Cheng; Li, Cui; Li, D; Li, D M; Li, F; Li, G; Li, H B; Li, J C; Li, K; Li, Lei; Li, P R; Li, Q J; Li, T; Li, W D; Li, W G; Li, X L; Li, X N; Li, X Q; Li, X R; Li, Z B; Liang, H; Liang, Y F; Liang, Y T; Liao, G R; Lin, D X; Liu, B J; Liu, C L; Liu, C X; Liu, F H; Liu, Fang; Liu, Feng; Liu, H B; Liu, H H; Liu, H M; Liu, J; Liu, J P; Liu, K; Liu, K Y; Liu, P L; Liu, Q; Liu, S B; Liu, X; Liu, Y B; Liu, Z A; Liu, Zhiqiang; Liu, Zhiqing; Loehner, H; Lou, X C; Lu, G R; Lu, H J; Lu, H L; Lu, J G; Lu, X R; Lu, Y; Lu, Y P; Luo, C L; Luo, M X; Luo, T; Luo, X L; Lv, M; Ma, F C; Ma, H L; Ma, Q M; Ma, S; Ma, T; Ma, X Y; Maas, F E; Maggiora, M; Malik, Q A; Mao, Y J; Mao, Z P; Messchendorp, J G; Min, J; Min, T J; Mitchell, R E; Mo, X H; Moeini, H; Morales, C Morales; Moriya, K; Muchnoi, N Yu; Nefedov, Y; Nikolaev, I B; Ning, Z; Nisar, S; Niu, X Y; Olsen, S L; Ouyang, Q; B, S Pacetti; Pelizaeus, M; Peng, H P; Peters, K; Ping, J L; Ping, R G; Poling, R; Prencipe, E; Qi, M; Qian, S; Qiao, C F; Qin, L Q; Qin, X S; Qin, Y; Qin, Z H; Qiu, J F; Rashid, K H; Redmer, C F; Ripka, M; Rong, G; Ruan, X D; Sarantsev, A; Schinning, K; Schumann, S; Shan, W; Shao, M; Shen, C P; Shen, X Y; Sheng, H Y; Shepherd, M R; Song, W M; Song, X Y; Spataro, S; Spruck, B; Sun, G X; Sun, J F; Sun, S S; Sun, Y J; Sun, Y Z; Sun, Z J; Sun, Z T; Tang, C J; Tang, X; Tapan, I; Thorndike, E H; Toth, D; Ullrich, M; B, I Uman; Varner, G S; Wang, B; Wang, D; Wang, D Y; Wang, K; Wang, L L; Wang, L S; Wang, M; Wang, P; Wang, P L; Wang, Q J; Wang, S G; Wang, W; Wang, X F; A, Y D Wang; Wang, Y F; Wang, Y Q; Wang, Z; Wang, Z G; Wang, Z H; Wang, Z Y; Wei, D H; Wei, J B; Weidenkaff, P; Wen, S P; Werner, M; Wiedner, U; Wolke, M; Wu, G G; Wu, L H; Wu, N; Wu, W; Wu, Z; Xia, L G; Xia, Y; Xiao, D; Xiao, Z J; Xie, Y G; Xiu, Q L; Xu, G F; Xu, L; Xu, Q J; Xu, Q N; Xu, X P; Xue, Z; Yan, L; Yan, W B; Yan, W C; Yan, Y H; Yang, H X; Yang, Y; Yang, Y X; Ye, H; Ye, M; Ye, M H; Yu, B X; Yu, C X; Yu, H W; Yu, J S; Yu, S P; Yuan, C Z; Yuan, W L; Yuan, Y; Zafar, A A; A, A Zallo; Zang, S L; Zeng, Y; Zhang, B X; Zhang, B Y; Zhang, C; Zhang, C B; Zhang, C C; Zhang, D H; Zhang, H H; Zhang, H Y; Zhang, J J; Zhang, J L; Zhang, J Q; Zhang, J W; Zhang, J Y; Zhang, J Z; Zhang, S H; Zhang, X J; Zhang, X Y; Zhang, Y; Zhang, Y H; Zhang, Z H; Zhang, Z P; Zhang, Z Y; Zhao, G; Zhao, J W; Zhao, Lei; Zhao, Ling; Zhao, M G; Zhao, Q; Zhao, Q W; Zhao, S J; Zhao, T C; Zhao, X H; Zhao, Y B; Zhao, Z G; Zhemchugov, A; Zheng, B; Zheng, J P; Zheng, Y H; Zhong, B; Zhou, L; Zhou, Li; Zhou, X; Zhou, X K; Zhou, X R; Zhou, X Y; Zhu, K; Zhu, K J; Zhu, X L; Zhu, Y C; Zhu, Y S; Zhu, Z A; Zhuang, J; Zou, B S; Zou, J H


    Using a sample of $1.06\\times10^{8}$ $\\psi(3686)$ events collected with the BESIII detector, we present the first observation of the decays of $\\psi(3686)$ $\\rightarrow$ $\\Lambda\\bar\\Sigma^{+}\\pi^{-}+c.c.$ and $\\psi(3686)$ $\\rightarrow$ $\\Lambda\\bar\\Sigma^{-}\\pi^{+}+c.c.$. The branching fractions are measured to be $\\mathcal{B}(\\psi(3686) \\rightarrow \\Lambda\\bar\\Sigma^{+}\\pi^{-} + c.c.)=(1.40\\pm 0.03 \\pm 0.13)\\times10^{-4}$ and $\\mathcal{B}(\\psi(3686) \\rightarrow \\Lambda\\bar\\Sigma^{-}\\pi^{+}+c.c.)=(1.54\\pm 0.04 \\pm 0.13)\\times10^{-4}$, where the first errors are statistical and the second ones systematic.

  2. C,C- and N,C-coupled dimers of 2-aminotetraphenylporphyrins: regiocontrolled synthesis, spectroscopic properties, and quantum-chemical calculations. (United States)

    Bruhn, Torsten; Witterauf, Franziska; Götz, Daniel C G; Grimmer, Carina T; Würtemberger, Max; Radius, Udo; Bringmann, Gerhard


    β,β'-Bisporphyrins are intrinsically chiral porphyrin dimers with fascinating properties. The configurational stability at their axes can be directed by variation of the central metal atoms. Herein, we present a regioselective functionalization of the monomeric 2-amino-tetraphenyl-porphyrin as a versatile substrate for dimerization by oxidative coupling. By simple variation of the reaction conditions (solvent and oxidant), the oxidation selectively gave either the axially chiral C,C-coupled diaminobisporphyrin in high yields or, under Ullmann conditions, the twofold N,C-linked achiral dimer, also in good yields. A generalized mechanism for the coupling reaction is proposed based on DFT calculations. The axially chiral β,β'-coupled porphyrin dimers were isolated as racemic mixtures, but can be resolved by HPLC on a chiral phase. TDDFT and coupled-cluster calculations were used to explain the spectroscopic properties of the aminoporphyrins and their dimers and to elucidate the absolute configurations of the C,C-coupled bisporphyrins.

  3. Photocatalytic C-C Bond Cleavage and Amination of Cycloalkanols by Cerium(III) Chloride Complex. (United States)

    Guo, Jing-Jing; Hu, Anhua; Chen, Yilin; Sun, Jianfeng; Tang, Haoming; Zuo, Zhiwei


    A general strategy for the cleavage and amination of C-C bonds of cycloalkanols has been achieved through visible-light-induced photoredox catalysis utilizing a cerium(III) chloride complex. This operationally simple methodology has been successfully applied to a wide array of unstrained cyclic alcohols, and represents the first example of catalytic C-C bond cleavage and functionalization of unstrained secondary cycloalkanols.

  4. Mathematical Simulation of Graphene With Modified c-c Bond Length and Transfer Energy


    P.A. Alvi; S.Z. Hashmi; S. Dalela; Rahman, F.


    In nanotechnology research, allotropes of carbon like Graphene, Fullerene (Buckyball) and Carbon nanotubes are widely used due to their remarkable properties. Electrical and mechanical properties of those allotropes vary with their molecular geometry. This paper is specially based on modeling and simulation of graphene in order to calculate energy band structure in k space with varying the C-C bond length and C-C transfer energy. Significant changes have been observed in the energy band struc...

  5. Evaluation by Rocket Combustor of C/C Composite Cooled Structure Using Metallic Cooling Tubes (United States)

    Takegoshi, Masao; Ono, Fumiei; Ueda, Shuichi; Saito, Toshihito; Hayasaka, Osamu

    In this study, the cooling performance of a C/C composite material structure with metallic cooling tubes fixed by elastic force without chemical bonding was evaluated experimentally using combustion gas in a rocket combustor. The C/C composite chamber was covered by a stainless steel outer shell to maintain its airtightness. Gaseous hydrogen as a fuel and gaseous oxygen as an oxidizer were used for the heating test. The surface of these C/C composites was maintained below 1500 K when the combustion gas temperature was about 2800 K and the heat flux to the combustion chamber wall was about 9 MW/m2. No thermal damage was observed on the stainless steel tubes that were in contact with the C/C composite materials. The results of the heating test showed that such a metallic tube-cooled C/C composite structure is able to control the surface temperature as a cooling structure (also as a heat exchanger) as well as indicated the possibility of reducing the amount of coolant even if the thermal load to the engine is high. Thus, application of this metallic tube-cooled C/C composite structure to reusable engines such as a rocket-ramjet combined-cycle engine is expected.

  6. Controlling the ambiphilic nature of σ-arylpalladium intermediates in intramolecular cyclization reactions. (United States)

    Solé, Daniel; Fernández, Israel


    The reactivity of main group organometallics, such as organolithium compounds (RLi) and Grignard reagents (RMgX), is quite straightforward. In these species the R group usually exhibits nucleophilic reactivity without any possibility of inducing electrophilic character. In contrast, in organopalladium complexes, researchers can switch the reactivity from electrophilic to nucleophilic relatively simply. Although σ-aryl and σ-vinylpalladium complexes are commonly used as electrophiles in C-C bond-forming reactions, recent research has demonstrated that they can also react with carbon-heteroatom multiple bonds in a nucleophilic manner. Nevertheless, researchers have completely ignored the issue of controlling the ambiphilic nature of such species. This Account describes our efforts toward selectively promoting the same starting materials toward either electrophilic α-arylation or nucleophilic addition reactions to different carbonyl groups. We could tune the properties of the σ-arylpalladium intermediates derived from amino-tethered aryl halides and carbonyl compounds to achieve chemoselective transformations. Therefore, chemists can control the ambiphilic nature of such intermediates and, consequently, the competition between the alternative reaction pathways by the adequate selection of the reaction conditions and additives (base, presence/absence of phenol, bidentate phosphines). The nature of the carbonyl group (aldehydes, ketones, esters, and amides) and the length of the tether connecting it to the aniline moiety also play an important role in the outcome of these processes. Our joint computational and experimental efforts to elucidate the reaction mechanism of these palladium-catalyzed transformations suggest that beyond the formation of the four-membered azapalladacycle, two major factors help to control the dual character of the palladium(II) intermediates derived from 2-haloanilines. First, their high nucleophilicity strongly modifies the interaction of

  7. Linux平台C/C++和汇编昆合编程%C/C++ Language and Assemble Language Combination Programming Based on Linux

    Institute of Scientific and Technical Information of China (English)

    郝丽花; 张世禄; 张杨军



  8. 使用Visual Leak Detector检测c/c++程序内存泄漏%Memory Leak Detection in c/c++ Programs with Visual Leak Detector

    Institute of Scientific and Technical Information of China (English)

    杨磊; 汪仁煌; 刘洪江; 黄颖怡


    针对内存泄漏检测问题,本文通过示例说明使用软件Visual Leal Detector 来检测泄漏点的方法.通过实验说明该方法在检测一般的c/c++程序内存泄漏时,可以提高检测效率.

  9. The interface between C/C++ and assembler in gcc/g++%gcc/g++下C/C++和汇编的接口

    Institute of Scientific and Technical Information of China (English)

    陈付龙; 汪迅宝; 李明东



  10. Unique properties of C,C'-linked nido-biscarborane tetraanions. Synthesis, structure and bonding of ruthenium monocarbollide via unprecedented cage carbon extrusion. (United States)

    Zhao, Da; Zhang, Jiji; Lin, Zhenyang; Xie, Zuowei


    Four reaction pathways have been found in the reaction of a C,C'-linked nido-biscarborane tetraanionic salt with [Ru(p-cymene)Cl2]2, leading to the isolation and structural characterization of redox, triple cage B-H oxidative addition, cage expansion and cage carbon extrusion products. Among these, the unprecedented cage carbon extrusion results in the formation of a new 6π-electron carboranyl ligand [C2B10H10](2-). The bonding interactions between this ligand and the Ru(ii) center have also been discussed on the basis of DFT calculations.

  11. Direct C-C Coupling of CO2 and the Methyl Group from CH4 Activation through Facile Insertion of CO2 into Zn-CH3 σ-Bond. (United States)

    Zhao, Yuntao; Cui, Chaonan; Han, Jinyu; Wang, Hua; Zhu, Xinli; Ge, Qingfeng


    Conversion of CO2 and CH4 to value-added products will contribute to alleviating the green-house gas effect but is a challenge both scientifically and practically. Stabilization of the methyl group through CH4 activation and facile CO2 insertion ensure the realization of C-C coupling. In the present study, we demonstrate the ready C-C coupling reaction on a Zn-doped ceria catalyst. The detailed mechanism of this direct C-C coupling reaction was examined based on the results from density functional theory calculations. The results show that the Zn dopant stabilizes the methyl group by forming a Zn-C bond, thus hindering subsequent dehydrogenation of CH4. CO2 can be inserted into the Zn-C bond in an activated bent configuration, with the transition state in the form of a three-centered Zn-C-C moiety and an activation barrier of 0.51 eV. The C-C coupling reaction resulted in the acetate species, which could desorb as acetic acid by combining with a surface proton. The formation of acetic acid from CO2 and CH4 is a reaction with 100% atom economy, and the implementation of the reaction on a heterogeneous catalyst is of great importance to the utilization of the greenhouse gases. We tested other possible dopants including Al, Ga, Cd, In, and Ni and found a positive correlation between the activation barrier of C-C coupling and the electronegativity of the dopant, although C-H bond activation is likely the dominant reaction on the Ni-doped ceria catalyst.

  12. Characteristics of an optimized active metal cast joint between copper and C/C

    Energy Technology Data Exchange (ETDEWEB)

    Schedler, B [Technology Centre of PLANSEE SE, A-6600 Reutte (Austria); Huber, T [Technology Centre of PLANSEE SE, A-6600 Reutte (Austria); Friedrich, T [Technology Centre of PLANSEE SE, A-6600 Reutte (Austria); Eidenberger, E [Department of Physical Metallurgy and Materials Testing, Montanuniversitaet Leoben, A-8700 Leoben (Austria); Kapp, M [Austrian Academy of Sciences, Erich-Schmid-Institute of Material Science, A-8700 Leoben (Austria); Scheu, C [Department of Physical Metallurgy and Materials Testing, Montanuniversitaet Leoben, A-8700 Leoben (Austria); Pippan, R [Austrian Academy of Sciences, Erich-Schmid-Institute of Material Science, A-8700 Leoben (Austria); Clemens, H [Department of Physical Metallurgy and Materials Testing, Montanuniversitaet Leoben, A-8700 Leoben (Austria)


    In this paper, an optimized active metal cast copper to carbon composite (C/C) joint is examined. Mechanical characterization by means of shear and tensile tests as well as fracture toughness measurements at ambient temperature are employed, which show that the obtained values are above those of the reference joint that has been used so far. The phases occurring at the interface region and the fracture surface of the optimized joint are investigated in detail to explain the improved mechanical behaviour. The composition and the morphology at the interface region are analysed by means of scanning electron microscopy. In addition, the crack path is analysed by stereomicroscopy. The improved properties can be explained by the circumstance that the fracture of the optimized joint is not restricted to the interface between the occurring carbide and the C/C but changes between C/C, the carbide to C/C interface and the copper, depending on the local structure in the C/C composite.

  13. Identification of Possible Pathways for C-C Bond Formation during Electrochemical Reduction of CO2: New Theoretical Insights from an Improved Electrochemical Model. (United States)

    Goodpaster, Jason D; Bell, Alexis T; Head-Gordon, Martin


    We have carried out a periodic Kohn-Sham density functional theory investigation of the pathways by which carbon-carbon bonds could be formed during the electrochemical reduction of CO2 on Cu(100) using a model that includes the effects of the electrochemical potential, solvent, and electrolyte. The electrochemical potential was set by relating the applied potential to the Fermi energy and then calculating the number of electrons required by the simulation cell for that specific Fermi energy. The solvent was included as a continuum dielectric, and the electrolyte was described using a linearized Poisson-Boltzmann model. The calculated potential of zero charge for a variety of surfaces agrees with experiment to within a mean average error of 0.09 V, thereby validating the assumptions of the model. Analysis of the mechanism for C-C bond formation revealed that at low-applied potential, C-C bond formation occurs through a CO dimer. However, at high applied potentials, a large activation barrier blocks this pathway; therefore, C-C bond formation occurs through reaction of adsorbed CHO and CO. Rate parameters determined from our calculations were used to simulate the kinetics of ethene formation during the electrochemical reduction of CO over a Cu(100) surface. An excellent match was observed between previously reported measurements of the partial current for ethene formation as a function of applied voltage and the variation in the partial current for C-C bond formation predicted by our microkinetic model. The electrochemical model reported here is simple, fairly easy to implement, and involves only a small increase in computational cost over calculations neglecting the effects of the electrolyte and the applied field. Therefore, it can be used to study the effects of applied potential and electrolyte composition on the energetics of surface reactions for a wide variety of electrochemical reactions.

  14. Characterization of Brazed Joints of C-C Composite to Cu-clad-Molybdenum (United States)

    Singh, M.; Asthana, R.


    Carbon-carbon composites with either pitch+CVI matrix or resin-derived matrix were joined to copper-clad molybdenum using two active braze alloys, Cusil-ABA (1.75% Ti) and Ticusil (4.5% Ti). The brazed joints revealed good interfacial bonding, preferential precipitation of Ti at the composite/braze interface, and a tendency toward de-lamination in resin-derived C-C composite due to its low inter-laminar shear strength. Extensive braze penetration of the inter-fiber channels in the pitch+CVI C-C composites was observed. The relatively low brazing temperatures (Cu-clad-Mo/braze interface and higher hardness in Ticusil (approx.85-250 HK) than in Cusil-ABA (approx.50-150 HK). These C-C/Cu-clad-Mo joints with relatively low thermal resistance may be promising for thermal management applications.

  15. Monitoring and Diagnostics for C/C++ Real-Time Applications

    CERN Document Server

    Fischer, Yves

    Knowledge about the internal state of computational processes is essential for problem diagnostics as well as for constant monitoring and pre-failure recognition. The CMX li- brary provides monitoring capabilities similiar to the Java Management Extensions (JMX) for C and C++ applications. This thesis provides a detailed analysis of the requirements for monitoring and diagnos- tics of the C/C++ processes at CERN. The developed CMX library enables real-time C/C++ processes to expose values with- out harming their normal execution. CMX is portable and can be integrated in different monitoring architectures.

  16. Experimental study on thermophysical properties of C/C composites at high temperature

    Institute of Scientific and Technical Information of China (English)

    ZHANG Wei; YI Fa-jun; HAN Jie-cai; MENG Song-he


    The coefficient of thermal expansion, thermal diffusivity and specific heat of C/C composites from room temperature to ultra high temperature were experimentally investigated. Thermal conductivity and thermal stress resistance of the composites were therefore computed based on experimental results. The results show that the composite has a very low thermal expansion coefficient. Thermal diffusivity decreases exponentially with temperature increase. The specific heat increases linearly as the temperature rises, and the variation trend of thermal conductivity is similar to that of thermal diffusivity. The thermal stress coefficient of C/C composite has little change with temperature variation, and thermal stress resistance of the composite at high temperature is stable.

  17. Development of C/C composite for the core component of the high temperature gas cooled reactor

    Energy Technology Data Exchange (ETDEWEB)

    Park, J. Y.; Kim, W. J.; Ryu, W. S.; Jang, J. H


    This report reviewed a state of the art on development of C/C composite for the core components for VHTR and described the followings items. The fabrication methods of C/C composites. Summary on the JAERI report (JAERI-Res 2002-026) on the process screening test for the selection of a proper C/C composite material. Review of the proceedings presented at the GEN-IV VHTR material PMB meeting. A status of the domestic commercial C/C composite. The published property data and the characteristics of the commercial C/C composite.

  18. Measurement of low-mass e{sup +}e{sup -} pair production in 1 and 2 A GeV C-C collision with HADES

    Energy Technology Data Exchange (ETDEWEB)

    Sudol, M.; Boyard, J.L.; Hennino, T.; Moriniere, E.; Ramstein, B.; Roy-Stephan, M. [CNRS/IN2P3 - Univ. Paris Sud, Inst. de Physique Nucleaire (UMR 8608), Orsay Cedex (France); Agakishiev, G.; Destefanis, M.; Gilardi, C.; Kirschner, D.; Kuehn, W.; Lange, J.S.; Metag, V.; Novotny, R.; Pechenov, V.; Pechenova, O.; Perez Cavalcanti, T.; Spataro, S.; Spruck, B. [Justus Liebig Universitaet Giessen, II. Physikalisches Institut, Giessen (Germany); Agodi, C.; Bellia, G.; Coniglione, R.; Finocchiaro, P.; Maiolino, C.; Piattelli, P.; Sapienza, P. [Istituto Nazionale di Fisica Nucleare-Laboratori Nazionali del Sud, Catania (Italy); Balanda, A.; Dybczak, A.; Kozuch, A.; Otwinowski, J.; Przygoda, W.; Salabura, P.; Trebacz, R.; Wisniowski, M.; Wojcik, T. [Jagiellonian Univ. of Cracow, Smoluchowski Inst. of Physics, Krakow (Poland); Belver, D.; Cabanelas, P.; Duran, I.; Garzon, J.A.; Lamas-Valverde, J.; Marin, J. [Univ. of Santiago de Compostela, Santiago de Compostela (Spain); Belyaev, A.; Chernenko, S.; Fateev, O.; Ierusalimov, A.; Zanevsky, Y. [Joint Inst. of Nuclear Research, Dubna (Russian Federation); Bielcik, J.; Braun-Munzinger, P.; Galatyuk, T.; Gonzalez-Diaz, D.; Heinz, T.; Holzmann, R.; Koenig, I.; Koenig, W.; Kolb, B.W.; Lang, S.; Muench, M.; Palka, M.; Pietraszko, J.; Rustamov, A.; Schroeder, C.; Schwab, E.; Simon, R.; Traxler, M.; Yurevich, S.; Zumbruch, P. [Gesellschaft fuer Schwerionenforschung mbH, Darmstadt (Germany); Blanco, A.; Ferreira-Marques, R.; Fonte, P.; Lopes, L.; Mangiarotti, A. [LIP-Lab. de Instrumentacao e Fisica Experimental de Particulas, Coimbra (Portugal); Bortolotti, A.; Iori, I.; Michalska, B. [Sezione di Milano, Istituto Nazionale di Fisica Nucleare, Milano (Italy); Christ, T.; Eberl, T.; Fabbietti, L.; Friese, J.; Gernhaeuser, R.; Jurkovic, M.; Kruecken, R.; Maier, L.; Sailer, B.; Schmah, A.; Weber, M. [Technische Univ. Muenchen, Munich (Germany); Diaz, J.; Gil, A. [Univ. de Valencia-CSIC, Valencia (Spain)] [and others


    HADES is a secondary generation experiment operated at GSI Darmstadt with the main goal to study dielectron production in proton, pion and heavy ion induced reactions. The first part of the HADES mission is to reinvestigate the puzzling pair excess measured by the DLS collaboration in C+C and Ca+Ca collisions at 1 A GeV. For this purpose dedicated measurements with the C+C system at 1 and 2 A GeV were performed. The pair excess above a cocktail of free hadronic decays has been extracted and compared to the one measured by DLS. Furthermore, the excess is confronted with predictions of various model calculations. (orig.)

  19. Asymmetric C-C Bond-Formation Reaction with Pd: How to Favor Heterogeneous or Homogeneous Catalysis?

    DEFF Research Database (Denmark)

    Reimann, S.; Grunwaldt, Jan-Dierk; Mallat, T.


    The enantioselective allylic alkylation of (E)-1,3-diphenylallyl acetate was studied to clarify the heterogeneous or homogeneous character of the Pd/Al2O3-(R)-BINAP catalyst system. A combined approach was applied: the catalytic tests were completed with in situ XANES measurements to follow...

  20. Preparation of Biomorphic SiC/C Ceramics from Pine Wood via Supercritical Ethanol Infiltration

    Institute of Scientific and Technical Information of China (English)


    Biomorphic (wood derived) carbide ceramics with an overall composition in the SiC/C was produced by supercritical ethanol infiltration of low viscosity tetraethylorthosilicate/supercritical ethanol into biologically derived carbon templates (CB-templates) and in situ hydrolysis into Si(OH)4-gel, the Si(OH)4-gel was calcined at 1400℃ to promote the polycondensation of Si(OH)4-gel into SiO2-phase and then carbonthermal reduction of the SiO2 with the biocarbon template into highly porous, biomorphic SiC/C ceramics. The phases and morphology conversion mechanism of resulting porous SiC/C ceramics have been investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Fourier transform infrared spectroscopy (FT-IR). Experimental results showed that the biomorphic cellular morphology of pinewood charcoal was remained in the porous SiC/C ceramic with high precision that consisted of β-SiC with minority of α-SiC and the remain free carbon existed in amorphous phase.

  1. Revis\\~ao da Constru\\c{c}\\~ao de Modelos Supersim\\'etricos

    CERN Document Server

    Rodríguez, M C


    Foi com base neste estudo que fizemos a constru\\c{c}\\~ao da vers\\~ao supersim\\'etrica dos modelos de simetria $SU(3)_{C} \\otimes SU(3)_{L} \\otimes U(1)_{N}$ \\cite{susy331}, apresentado no final da minha tese de doutorado \\cite{mcr1}. Bem como dos estudos fenomenol\\'ogicos subsequente \\cite{mcr}.

  2. Extraction and Visualization of Call Dependencies for Large C/C++ Code Bases : A Comparative Study

    NARCIS (Netherlands)

    Telea, Alexandru; Hoogendorp, Hessel; Ersoy, Ozan; Reniers, Dennie; Lanza, M; Storey, M; Muller, H


    Investigating program dependencies such as function calls is challenging for very large systems. We present here an integrated pipeline for extraction and visualization of call-and-hierarchy graphs for C/C++ programs. We present several adaptions and enhancements of a recent visualization method for

  3. Al2O3-SiC-C Bricks for Hot Metal Pretreatment

    Institute of Scientific and Technical Information of China (English)


    @@ 1 Scope This standard specifies the classification,techni-cal requirements,test methods,inspection rules,packing,marking,transportation,storage and quality certificate of Al2O3-SiC-C bricks for hot metal pre-treatment.

  4. Al2O3 SiC-C Bricks for Hot Metal Pretreatment

    Institute of Scientific and Technical Information of China (English)

    Yu Lingyan; Peng Xigao


    @@ 1 Scope This standard specifies the classification,shape and dimensions,technical requirements,test methods,quality appraisal procedures,packing,marking,transportation,storage,and quality certificate of Al2O3SiC-C bricks for hot metal pretreatment.

  5. Re-mediated C-C coupling of pyridines and imidazoles. (United States)

    Espinal Viguri, Maialen; Huertos, Miguel A; Pérez, Julio; Riera, Lucía; Ara, Irene


    Rhenium tricarbonyl complexes with three N-heterocyclic ligands (N-alkylimidazoles or pyridines) undergo deprotonation with KN(SiMe(3))(2) and then oxidation with AgOTf to afford complexes with pyridylimidazole or bipyridine bidentate ligands resulting from deprotonation, C-C coupling and rearomatization.

  6. Imidazole-nitrile or imidazole-isonitrile C-C coupling on rhenium tricarbonyl complexes. (United States)

    Viguri, Maialen Espinal; Huertos, Miguel A; Pérez, Julio; Riera, Lucía


    Ligand activation: Deprotonation of the nitrile or isonitrile complexes [Re(CO)3(N-RIm)2(L)](+) (N-RIm = N-alkylimidazole; L = N≡CtBu, C≡NtBu) selectively afforded alkylidenamido or iminoacyl derivatives, respectively, in which C-C coupling has occurred. Protonation of the latter complex leads to aminocarbene products.

  7. 77 FR 10004 - C$ cMoney, Inc.; Order of Suspension of Trading (United States)


    ... COMMISSION C$ cMoney, Inc.; Order of Suspension of Trading February 16, 2012. It appears to the Securities... the opinion that the public interest and the protection of investors require a suspension of trading... the Securities Exchange Act of 1934, that trading in the securities of the above-listed company...

  8. Complex of 2-(methylthio)aniline with palladium(II) as an efficient catalyst for Suzuki–Miyaura C-C coupling in eco-friendly water

    Energy Technology Data Exchange (ETDEWEB)

    Rao, Gyandshwar K.; Kumar, Arun; Bhunia, Mrinal; Singh, Mahabir P.; Singh, Ajai Kumar, E-mail:


    Graphical abstract: - Highlights: • Synthesis of palladium complex of a bidentate ligand of (N, S) type. • Determination of single crystal structure of the complex. • Complex showed excellent activity for Suzuki–Miyaura coupling reactions in water. • TON values up to 93,000 were achieved. - Abstract: 2-(Methylthio)aniline (L1), a bidentate (S,N) ligand synthesized by the reaction of o-aminothiophenol with methyl iodide, on reacting with Na{sub 2}PdCl{sub 4} in acetone and water gives a complex [PdL1Cl{sub 2}] (1). Single crystal X-ray diffraction studies have revealed that the geometry of palladium in 1 is nearly square-planar and the ligand L1 is bound to the palladium through S and N in a bidentate coordination mode forming a five membered chelate ring. This complex functions as a thermally and air stable catalyst of high efficiency for Suzuki–Miyaura C-C coupling reactions in water. It catalyzes C-C coupling between various aryl bromides and phenylboronic acid under mild reaction conditions in water. TON value up to 93,000 has been obtained.

  9. Oxidation mechanisms and kinetics of 1D-SiC/C/SiC composite materials; 1: An experimental approach

    Energy Technology Data Exchange (ETDEWEB)

    Filipuzzi, L.; Camus, G.; Naslain, R. (Domaine Univ., Pessac (France). Lab. des Composites Thermostructuraux); Thebault, J. (Societe Europeenne de Propulsion, Saint Medard en Jalles (France))


    The oxidation of unidirectional SiC/C/SiC model composites has been investigated through thermogravimetric analysis, optical/electron microscopy, and electrical measurements. The influence of temperature and carbon interphase thickness on the oxidation of the composites is discussed. The oxidation involves three phenomena: (1) reaction of oxygen with the carbon interphase resulting in pores around the fibers, (2) diffusion of oxygen and carbon oxides along the pores, and (3) reaction of oxygen with the pore walls leading to the growth of silica layers on both the fibers and matrix. In composites with a thin carbon interphase treated at T > 1,000 C the pores are rapidly sealed by silica. Under such conditions, the oxidation damages are limited to the vicinity of the external surface and the materials exhibit a self-healing character. Conversely, long exposures at 900 C give rise to the formation of microcracks in the matrix related to mechanical stresses arising from the in situ SiC/SiO[sub 2] conversion. Finally, the self-heating character is not observed in composites with a thick interphase since carbon is totally consumed before silica can seal the pores.

  10. Inhibition of chemokine (C-C motif receptor 7 sialylation suppresses CCL19-stimulated proliferation, invasion and anti-anoikis.

    Directory of Open Access Journals (Sweden)

    Mei-Lin Su

    Full Text Available Chemokine (C-C motif receptor 7 (CCR7 is involved in lymph-node homing of naive and regulatory T cells and lymphatic metastasis of cancer cells. Sialic acids comprise a group of monosaccharide units that are added to the terminal position of the oligosaccharide chain of glycoproteins by sialyation. Recent studies suggest that aberrant sialylation of receptor proteins contributes to proliferation, motility, and drug resistance of cancer cells. In this study, we addressed whether CCR7 is a sialylated receptor protein and tried to elucidate the effect of sialylation in the regulation of signal transduction and biological function of CCR7. Our results demonstrated that α-2, 3-sialyltransferase which catalyze sialylation reaction in vivo was overexpressed in breast tumor tissues and cell lines. Lectin blot analysis clearly demonstrated that CCR7 receptor was sialyated in breast cancer cells. Chemokine (C-C motif ligand 19 (CCL19, the cognate ligand for CCR7, induced the activation of extracellular signal-regulated kinase (ERK and AKT signaling and increased the expression of cell cycle regulatory proteins and proliferation of breast cancer cells. When cells were pre-treated with a sialyltransferase inhibitor AL10 or sialidase, CCL19-induced cell growth was significantly suppressed. CCL19 also increased invasion and prevented anoikis by up-regulating pro-survival proteins Bcl-2 and Bcl-xL. Inhibition of sialylation by AL10 totally abolished these effects. Finally, we showed that AL10 inhibited tumorigenicity of breast cancer in experimental animals. Taken together, we demonstrate for the first time that CCR7 receptor is a sialylated protein and sialylation is important for the paracrine stimulation by its endogenous ligand CCL19. In addition, inhibition of aberrant sialylation of CCR7 suppresses proliferation and invasion and triggers anoikis in breast cancer cells. Targeting of sialylation enzymes may be a novel strategy for breast cancer treatment.

  11. Universal Brønsted-Evans-Polanyi Relations for C–C, C–O, C–N, N–O, N–N, and O–O Dissociation Reactions

    DEFF Research Database (Denmark)

    Wang, Shengguang; Temel, Burcin; Shen, Juan


    It is shown that for all the essential bond forming and bond breaking reactions on metal surfaces, the reactivity of the metal surface correlates linearly with the reaction energy in a single universal relation. Such correlations provide an easy way of establishing trends in reactivity among the ...

  12. Accurate Reaction Enthalpies and Sources of Error in DFT Thermochemistry for Aldol, Mannich, and α-Aminoxylation Reactions (United States)

    Wheeler, Steven E.; Moran, Antonio; Pieniazek, Susan N.; Houk, K. N.


    Enthalpies for bond-forming reactions that are subject to organocatalysis have been predicted using the high-accuracy CBS-QB3 model chemistry and six DFT functionals. Reaction enthalpies were decomposed into contributions from changes in bonding and other intramolecular effects via the hierarchy of homodesmotic reactions. The order of the reaction exothermicities (aldol < Mannich ≈ α-aminoxylation) arises primarily from changes in formal bond types mediated by contributions from secondary intramolecular interactions. In each of these reaction types, methyl substitution at the β- and γ-positions stabilizes the products relative to the unsubstituted case. The performance of six DFT functionals (B3LYP, B3PW91, B1B95, MPW1PW91, PBE1PBE, and M06-2X), MP2, and SCS-MP2 has been assessed for the prediction of these reaction enthalpies. Even though the PBE1PBE and M06-2X functionals perform well for the aldol and Mannich reactions, errors roughly double when these functionals are applied to the α-aminoxylation reactions. B3PW91 and B1B95, which offer modest accuracy for the aldol and Mannich reactions, yield reliable predictions for the two α-aminoxylation reactions. The excellent performance of the M06-2X and PBE1PBE functionals for aldol and Mannich reactions stems from the cancellation of sizable errors arising from inadequate descriptions of the underlying bond transformations and intramolecular interactions. SCS-MP2/cc-pVTZ performs most consistently across these three classes of reactions, although the reaction exothermicities are systematically underestimated by 1-3 kcal mol-1. Conventional MP2, when paired with the cc-pVTZ basis set, performs somewhat better than SCS-MP2 for some of these reactions, particularly the α-aminoxylations. Finally, the merits of benchmarking DFT functionals for the set of simple chemically meaningful transformations underlying all bond-forming reactions are discussed.

  13. Mo2C改性涂层制备温度对C/C-Cu复合材料组织和性能的影响%Influence of preparation temperature of Mo2C interlayer on microstructure and properties of C/C-Cu composites

    Institute of Scientific and Technical Information of China (English)

    周文艳; 易茂中; 冉丽萍; 彭可; 葛毅成


    In order to improve the wetting ability between molten copper and C/C preform, Mo2C interlayer was fabricated on the internal surface of C/C preform via molten salt deposition using ammonium paramolybdate as reactant. Then, C/C-Cu composites were prepared by pressureless infiltration. The influences of preparation temperature of Mo2C interlayer on the microstructure and properties of Mo2C interlayer and C/C-Cu composite were investigated. The results show that the Mo2C interlayer covered internal pore surface of the C/C preform uniformly has a good interface bonding with C/C substrate and Cu. With the increase of preparation temperature in the range of 950−1150℃, the thickness of the Mo2C interlayer increases from 2.0 μm to 6.5 μm, the density of C/C-Cu composite increases, the electrical resistivity decreases, the flexural strength firstly increases and then decreases, and reaches the maximum value (251.83 MPa) at 1000 ℃. The friction coefficient of the C/C-Cu composite firstly increases and then decreases to a stable value with friction time increasing. With the increase of the reaction temperature, the friction coefficient increases, the volume abrasion rate firstly decreases and then increases, and reaches the minimum value at 1000℃.%以仲钼酸铵为反应物,采用熔盐法在低密度C/C复合材料孔隙表面制备Mo2C涂层,改善Cu与C/C坯体的润湿性,然后通过无压熔渗Cu制备C/C-Cu复合材料,研究了Mo2C改性层制备温度对Mo2C涂层和C/C-Cu复合材料组织结构及性能的影响。结果表明:Mo2C涂层在坯体内部孔隙表面分布均匀,且与炭基体和Cu均有良好的界面结合。在950~1150℃范围内,随涂层反应温度的提高,Mo2C层厚度由2.0μm逐渐增大到6.5μm,C/C-Cu复合材料的密度逐渐增大,电阻率逐渐降低;抗弯强度呈现先增大后减小趋势,在涂层反应温度为1000℃时呈现最大值251.83 MPa。复合材料的摩擦因数均随磨损时

  14. Thermo-mechanical and tribological properties of phenolic polymers composites and C-C composites

    Directory of Open Access Journals (Sweden)

    Virgil MARINESCU


    Full Text Available Formaldehyde resin-based composites have been an inaugural step in obtaining and usingcomposite materials and they have grown rapidly because of their multiple uses, especially inelectrical and aeronautical field.Phenolic matrix composites represent a preliminary study to obtain mezophase carbon-carboncomposites for advanced materials as potential solutions for reentry shields of cosmic vehicles andlaunch subsystems, as elements of modern braking systems in aircraft or as potential solutions for thecomponents of the combustion chamber of rockets and also as hypersonic transport solutions for thefuture. Both phenolic matrix laminated composites and C-C mezophase matrix C-C composites wereobtained.This paper presents an evaluation of the mechanical and tribological behavior of the obtainedcomposites.

  15. Influence of additives on oxidation resistance of binderless C/C composite

    Institute of Scientific and Technical Information of China (English)

    周声劢; 刘其城; 胡晓凯


    Experiment of adding B4C, SiC, and Si powders to improve oxidation resistance of the C/C compositeswas carried out. The results show that the increase of oxidation resistance is remarkable when the contents of B4C,SiC, and Si powders are 10%, 10%, and 5% in the composites, respectively. The regularities and mechanism ofthe effects of the ceramic powders on the oxidation resistance of the composites were also discussed.

  16. Long-term tropospheric trend of octafluorocyclobutane (c-C4F8 or PFC-318

    Directory of Open Access Journals (Sweden)

    T. Röckmann


    Full Text Available Air samples collected at Cape Grim, Tasmania between 1978 and 2008 and during a series of more recent aircraft sampling programmes have been analysed to determine the atmospheric abundance and trend of octafluorocyclobutane (c-C4F8 or PFC-318. c-C4F8 has an atmospheric lifetime in excess of 3000 yr and a global warming potential (GWP of 10 300 (100 yr time horizon, making it one of the most potent greenhouse gases detected in the atmosphere to date. The abundance of c-C4F8 in the Southern Hemisphere has risen from 0.35 ppt in 1978 to 1.2 ppt in 2010, and is currently increasing at a rate of around 0.03 ppt yr−1. It is the third most abundant perfluorocarbon (PFC in the present day atmosphere, behind CF4 (~75 ppt and C2F6 (~4 ppt. Although a number of potential sources of c-C4F8 have been reported, including the electronics and semi-conductor industries, there remains a large discrepancy in the atmospheric budget. Using a 2-D global model to derive top-down global emissions based on the Cape Grim measurements yields a recent (2007 emission rate of around 1.1 Gg yr−1 and a cumulative emission up to and including 2007 of 38.1 Gg. Emissions reported on the EDGAR emissions database for the period 1986–2005 represent less than 1% of the top-down emissions for the same period, which suggests there is a large unaccounted for source of this compound. It is also apparent that the magnitude of this source has varied considerably over the past 30 yr, declining sharply in the late 1980s before increasing again in the mid-1990s.

  17. Monte Carlo Simulation of Electron Swarms Parameters in c-C4F8/CF4 Gas Mixtures

    Institute of Scientific and Technical Information of China (English)

    LIU Xue-li; XIAO Deng-ming; WANG Yan-an; ZHANG Zhou-sheng


    The swarm parametes for c-C4F8/CF4 mixtures, including the density-normalized effective ionization coefficient, drift velocity and mean energy were calculated using Monte-Carlo method with the null collision technique. The overall density-reduced electric field strength could be varied between 150 and 500 Td,while the c-C4F8 content in gas mixtures is varied in the range of 0-100%. The value of the density-normalize deffective ionization coefficient shows a strong dependence on the c-C4F8 content, becoming more electronegative as the content of c-C4F8 is increased. The drift velocity of c-C4F4/CF4 mixtures is more affected by CF4. The calculated limiting field strength for c-C4F8/CF4 mixtures is higher than that of SF6/CF4.

  18. C/C-SiC Composites for Nozzle of Solid Propellant Ramjet

    Directory of Open Access Journals (Sweden)

    WANG Lingling


    Full Text Available Carbon fiber reinforced carbon and silicon carbide matrix composites for nozzle inner of solid propellant ramjet were prepared by using the hybrid process of "chemical vapor infiltration + precursor impregnation pyrolysis (CVI+PIP". The microstructure, flexural and anti-ablation properties of the C/C-SiC composites and hydraulic test and rocket motor hot firing test for nozzle inner of solid propellant ramjet were comprehensively investigated. The results show that when the flexural strength of the composite reachs 197 MPa, the fracture damage behavior of the composites presents typical toughness mode.Also the composites has excellent anti-ablative property, i.e., linear ablation rate is only 0.0063 mm·s-1 after 200 s ablation. The C/C-SiC component have excellent integral bearing performance with the hydraulic bursting pressure of 6.5 MPa, and the high temperature combination property of the C/C-SiC composite nozzle inner is verified through motor hot firing of solid propellant ramjet.

  19. A C/C++ Build System Based On Maven for the LHC Controls System

    CERN Document Server

    Nguyen Xuan, J; Dönszelmann, M


    The CERN accelerator controls system, mainly written in Java and C/C++, consists nowadays of 50 projects and 150 active developers. The controls group has decided to unify the development process and standards (e.g. project layout) using Apache Maven and Sonatype Nexus. Maven is the de-facto build tool for Java, it deals with versioning and dependency management, whereas Nexus is a repository manager. C/C++ developers were struggling to keep their dependencies on other CERN projects, as no versioning was applied, the libraries have to be compiled and available for several platforms and architectures, and finally there was no dependency management mechanism. This results in very complex Makefiles which were difficult to maintain. Even if Maven is primarily designed for Java, a plugin (Maven NAR) adapts the build process for native programming languages for different operating systems and platforms. However C/C++ developers were not keen to abandon their current Makefiles. Hence our approach was to combine the ...

  20. Determination of material properties for short fibre reinforced C/C-SiC

    Directory of Open Access Journals (Sweden)

    Hausherr J.-M.


    Full Text Available Determining the mechanical properties of short fibre reinforced CMC using standard sized coupons has always been a challenge due to a high statistical scattering of the measured values. Although the random orientation of short fibres results in a quasi-isotropic material behavior of 2D-structures with a sufficiently large volume, the small volume typical for test coupons usually results in a non-isotropic fibre orientation in the tested volume. This paper describes a method for manufacturing unidirectional oriented short fibre reinforced CMC materials and presents material properties of UD-C/C-SiC. After verifying the fibre orientation of the CMC using micro-computed tomography, coupons were extracted to determine the orthotropic material properties. These orthotropic material properties were then used to predict the properties of C/C-SiC with randomly distributed short fibres. To validate the method, micro-computed tomography is used to quantitatively determine the fibre orientation within coupons extracted from randomly distributed short fibre C/C-SiC. After mechanical three-point-bending tests, the measured stiffness and bending strength is compared with the predicted properties. Finally, the data are used to devise a method suited for reducing the inherent large spread of material properties associated with the measurement of CMC materials with randomly distributed short fibres.

  1. Efficient anodic and direct phenol-arene C,C cross-coupling: the benign role of water or methanol. (United States)

    Kirste, Axel; Elsler, Bernd; Schnakenburg, Gregor; Waldvogel, Siegfried R


    C,C cross-coupling reactions for the synthesis of nonsymmetrical biaryls represent one of the most significant transformations in contemporary organic chemistry. A variety of useful synthetic methods have been developed in recent decades, since nonsymmetrical biaryls play an evident role in natural product synthesis, as ligand systems in homogeneous catalysis and materials science. Transformation of simple arenes by direct C,H activation belongs to the cutting-edge strategies for creating biaryls; in particular the 2-fold C,H activation is of significant interest. However, in most examples very costly noble metal catalysts, ligand systems, and significant amount of waste-producing oxidants are required. Electrochemical procedures are considered as inherently "green" methods, because only electrons are required and therefore, no reagent waste is produced. Here, we report a metal-free electrochemical method for cross-coupling between phenols and arenes using boron-doped diamond (BDD) anodes in fluorinated media. Our sustainable approach requires no leaving functionalities. Employing water or methanol as mediator represents the key improvement for achieving nonsymmetrical biaryls with superb selectivity and synthetic attractive yields.

  2. Long-term tropospheric trend of octafluorocyclobutane (c-C4F8 or PFC-318

    Directory of Open Access Journals (Sweden)

    T. Röckmann


    Full Text Available Air samples collected at Cape Grim, Tasmania between 1978 and 2008 and during a series of more recent aircraft sampling programmes have been analysed to determine the atmospheric abundance and trend of octafluorocyclobutane (-C4F8 or PFC-318. c-C4F8 has an atmospheric lifetime in excess of 3000 yr and a global warming potential (GWP of 10 300 (100 yr time horizon, making it one of the most potent greenhouse gases detected in the atmosphere to date. The abundance of c-C4F8 in the Southern Hemisphere has risen from 0.35 ppt in 1978 to 1.2 ppt in 2010, and is currently increasing at a rate of around 0.03 ppt yr−1. It is the third most abundant perfluorocarbon (PFC in the present day atmosphere, behind CF4 (~75 ppt and C2F6 (~4 ppt. The origin of c-C4F8 is unclear. Using a 2-D global model to derive top-down global emissions based on the Cape Grim measurements yields a recent (2007 emission rate of around 1.1 Gg yr−1 and a cumulative emission up to and including 2007 of 38.1 Gg. Emissions reported on the EDGAR emissions database for the period 1986–2005 represent less than 1 % of the top-down emissions for the same period, which suggests there is a large unaccounted for source of this compound. It is also apparent that the magnitude of this source has varied considerably over the past 30 yr, declining sharply in the late 1980s before increasing again in the mid-1990s.

  3. Measurement of Swarm Parameters of c-C4F8/CO2 and Its Insulation Characteristics Analysis

    Institute of Scientific and Technical Information of China (English)

    ZHANG Liu-chun; XIAO Deng-ming; ZHANG Dong; WU Bian-tao


    In c-C4F8 and c-C4F8/CO2 mixtures, the swarm parameters including ionization coefficient, attachment coefficient and effective ionization coefficient were obtained at the ratio of the electric field strength to the gas density between 150-550 Td by the steady-state Townsend (SST) method. Static breakdown voltages at each ratio were also measured at the SST condition. The limiting field strengths were obtained by two methods:computing the density-normalized effective ionization coefficient as a function of the overall density-reduced electric field strength; and measuring static breakdown voltages as a function of the product of gas density and electrode separation. Good agreement was obtained by these two methods, which ensures the correctness of the former method. The limiting field strengths of c-C4F8 and c-C4F8/CO2 mixtures were compared with those ofpure SF6, SF6/CO2 mixtures and pure c-C4Fs. It is found that buffer gas CO2 does not reduce the limiting field strengths of c-C4F8 greatly, the limiting field strengths of c-C4F8/CO2 mixtures are higher than those of SF6/CO2 mixtures or even pure SF6, and so c-C4F8/CO2 mixtures are suggested to be possible substitutes for SF6.

  4. The large 1 1Ag - 2 1Ag C=C stretching vibronic interaction in all-trans polyenes

    NARCIS (Netherlands)

    Buma, W.J.; Zerbetto, F.


    An ab initio theoretical approach at several levels of theory is employed to calculate the 11Ag--21Ag- (non)adiabatic vibronic couplings induced by the completely in-phase C=C and C-C bond stretching vibrations of five all-trans polyenes (from butadiene to dodecahexaene). The nonadiabatic couplings

  5. 77 FR 12578 - Notice of Intent To Grant Exclusive Patent License; C&C Ventures, Doing Business as Randolph... (United States)


    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF DEFENSE Department of the Navy Notice of Intent To Grant Exclusive Patent License; C&C Ventures, Doing Business as... hereby gives notice of its intent to grant to C&C Ventures, doing business as Randolph Products,...

  6. Charged pion production in C+C and Ar+KCl collisions measured with HADES

    CERN Document Server

    Tlustý, P; Balanda, A; Bellia, G; Belver, D; Belyaev, A; Blanco, A; Boehmer, M; Boyard, J L; Braun-Munzinger, P; Cabanelas, P; Castro, E; Chernenko, S; Christ, T; Destefanis, M; Díaz, J; Dohrmann, F; Dybczak, A; Fabbietti, L; Fateev, O; Finocchiaro, P; Fonte, P; Friese, J; Fröhlich, I; Galatyuk, T; Garzón, J A; Gernhäuser, R; Gil, A; Gilardi, C; Golubeva, M; Gonzalez-Diaz, D; Grosse, E; Guber, F; Heilmann, M; Hennino, T; Holzmann, R; Ierusalimov, A; Iori, I; Ivashkin, A; Jurkovic, M; Kämpfer, B; Kanaki, K; Karavicheva, T; Kirschner, D; König, I; König, W; Kolb, B W; Kotte, R; Kozuch, A; Krasa, A; Krizek, F; Krücken, R; Kühn, W; Kugler, A; Kurepin, A; Lamas-Valverde, J; Lang, S; Lange, J S; Lapidus, K; Liu, T; Lopes, L; Lorenz, M; Maier, L; Mangiarotti, A; Marin, J; Markert, J; Metag, V; Michalska, B; Michel, J; Mishra, D; Moriniere, E; Mousa, J; Müntz, C; Naumann, L; Novotny, R; Otwinowski, J; Pachmayer, Y C; Palka, M; Parpottas, Y; Pechenov, V; Pechenova, O; Cavalcanti, T Perez; Pietraszko, J; Przygoda, W; Ramstein, B; Reshetin, A; Rustamov, A; Sadovskii, A; Salabura, P; Schmah, A; Simon, R; Sobolev, Yu G; Spataro, S; Spruck, B; Ströbele, H; Stroth, J; Sturm, C; Sudol, M; Tarantola, A; Teilab, K; Traxler, M; Trebacz, R; Tsertos, H; Veretenkin, I; Wagner, V; Weber, M; Wisniowski, M; Wüstenfeld, J; Yurevich, S; Zanevsky, Y; Zhou, P; Zumbruch, P


    Results of a study of charged pion production in 12C+12C collisions at incident beam energies of 1A GeV and 2A GeV, and 40Ar+natKCl at 1.76AGeV, using the spectrometer HADES at GSI, are presented. We have performed a measurement of the transverse momentum distributions of pi+- mesons covering a fairly large rapidity interval, in case of the C+C collision system for the first time. The yields, transverse mass and angular distributions are compared with a transport model as well as with existing data from other experiments.

  7. Study of dielectron production in C+C collisions at 1 AGeV

    CERN Document Server

    Agakichiev, G; Pol, H Alvarez; Balanda, A; Bassini, R; Bellia, G; Belver, D; Belyaev, A; Blanco, A; Boehmer, M; Bortolotti, A; Boyard, J L; Braun-Munzinger, P; Cabanelas, P; Castro, E; Christ, T; Destefanis, M; Díaz, J; Dohrmann, F; Dybczak, A; Eberl, T; Fabbietti, L; Finocchiaro, P; Fonte, Paulo J R; Friese, J; Fröhlich, I; Galatyuk, T; Garzón, J A; Gernhäuser, R; Gil, A; Gilardi, C; Golubeva, M; Diaz, D Gonzalez; Grosse, E; Guber, F; Heilmann, M; Hennino, T; Holzmann, R; Ierusalimov, A; Iori, I; Ivashkin, A; Jurkovic, M; Kämpfer, B; Kanaki, K; Karavicheva, T; Kirschner, D; König, I; König, W; Kolb, B W; Kotte, R; Kozuch, A; Krasa, A; Krizek, F; Krücken, R; Kühn, W; Kugler, A; Kurepin, A; Valverde, J Lamas; Lang, S; Lange, J S; Lapidus, K; Lopes, L; Maier, L; Mangiarotti, A; Marin, J; Markert, J; Metag, V; Michalska, B; Mishra, D; Moriniere, E; Mousa, J; Münch, M; Müntz, C; Naumann, Lutz; Novotny, R; Otwinowski, J; Pachmayer, Y C; Palka, M; Parpottas, Y; Pechenov, V; Pechenova, O; Perez, T; Pietraszko, J; Pleskac, R; Przygoda, W; Ramstein, B; Reshetin, A; Stephan, M Roy; Rustamov, A; Sadovskii, A; Sailer, B; Salabura, P; Schmah, A; Simon, R; Sobolev, Y; Spataro, S; Spruck, B; Ströbele, H; Stroth, J; Sturm, C; Sudol, M; Tarantola, A; Teilab, K; Tlustý, P; Toia, A; Traxler, M; Trebacz, R; Tsertos, H; Veretenkin, I; Wagner, V; Weber, M; Wen, H; Wisniowski, M; Wojcik, T; Wüstenfeld, J; Yurevich, S; Zanevsky, Y; Zhou, P; Zumbruch, P


    The emission of e+e- pairs from C+C collisions at an incident energy of 1 GeV per nucleon has been investigated. The measured production probabilities, spanning from the pi0-Dalitz to the rho/omega! invariant-mass region, display a strong excess above the cocktail of standard hadronic sources. The bombarding-energy dependence of this excess is found to scale like pion production, rather than like eta production. The data are in good agreement with results obtained in the former DLS experiment.

  8. An erbium-based bifuctional heterogeneous catalyst: a cooperative route towards C-C bond formation. (United States)

    Oliverio, Manuela; Costanzo, Paola; Macario, Anastasia; De Luca, Giuseppina; Nardi, Monica; Procopio, Antonio


    Heterogeneous bifuctional catalysts are multifunctional synthetic catalysts enabling efficient organic transformations by exploiting two opposite functionalities without mutual destruction. In this paper we report the first Er(III)-based metallorganic heterogeneous catalyst, synthesized by post-calcination MW-assisted grafting and modification of the natural aminoacid L-cysteine. The natural acid-base distance between sites was maintained to assure the cooperation. The applicability of this new bifunctional heterogeneous catalyst to C-C bond formation and the supposed mechanisms of action are discussed as well.

  9. Microanalysis on the Hydrogen Ion Irradiated 50 wt pct TiC-C Films

    Institute of Scientific and Technical Information of China (English)

    Hui JIANG; Yaoguang LIU; Ningkang HUANG


    The 50 wt pct TiC-C films were prepared on stainless steel substrates by using a technique of ion beam mixing.These films were irradiated by hydrogen ion beam with a dose of 1×1018 ions/cm2 and an energy of 5 keV.Microanalysis of X-ray photoelectron spectroscopy (XPS) and secondary ion mass spectroscopy (SIMS) were used to analyze the films before and after hydrogen ion irradiation and to study the mechanism of hydrogen resistance.

  10. Homolytic Bond Dissociation Enthalpies of C C and C-H Bonds in Highly Crowded Alkanes

    Institute of Scientific and Technical Information of China (English)

    ZHU Chen; RUI Lei; FU Yao


    The homolytic C-C and C--H bond dissociation enthalpyies (BDE) of highly crowded alkanes were calcu- lated by using an ONIOM-G3B3 method. Geometric parameters such as bond length, bond angle and molecular volume were carefully investigated, as most of the acyclic alkanes in this study were not yet synthesized. These pa-rameters reflect the influence of steric effect on BDE. Good correlations were found between the rapid decrease of BDE and the increase of molecular volumes. The correlations can be applied to the prediction of the possible exis-tence of many highly strained compounds.

  11. An Erbium-Based Bifuctional Heterogeneous Catalyst: A Cooperative Route Towards C-C Bond Formation

    Directory of Open Access Journals (Sweden)

    Manuela Oliverio


    Full Text Available Heterogeneous bifuctional catalysts are multifunctional synthetic catalysts enabling efficient organic transformations by exploiting two opposite functionalities without mutual destruction. In this paper we report the first Er(III-based metallorganic heterogeneous catalyst, synthesized by post-calcination MW-assisted grafting and modification of the natural aminoacid L-cysteine. The natural acid–base distance between sites was maintained to assure the cooperation. The applicability of this new bifunctional heterogeneous catalyst to C-C bond formation and the supposed mechanisms of action are discussed as well.

  12. Activation of Aromatic C-C Bonds of 2,2'-Bipyridine Ligands. (United States)

    Fombona, Sergio; Espinal-Viguri, Maialen; Huertos, Miguel A; Díaz, Jesús; López, Ramón; Menéndez, M Isabel; Pérez, Julio; Riera, Lucía


    4,4'-Disubstituted-2,2'-bipyridine ligands coordinated to Mo(II) and Re(I) cationic fragments become dearomatized by an intramolecular nucleophilic attack from a deprotonated N-alkylimidazole ligand in cis disposition. The subsequent protonation of these neutral complexes takes place on a pyridine carbon atom rather than at nitrogen, weakening an aromatic C-C bond and affording a dihydropyridyl moiety. Computational calculations allowed for the rationalization of the formation of the experimentally obtained products over other plausible alternatives.

  13. Metal-catalyzed asymmetric aldol reactions

    Energy Technology Data Exchange (ETDEWEB)

    Dias, Luiz C.; Lucca Junior, Emilio C. de; Ferreira, Marco A. B.; Polo, Ellen C., E-mail: [Universidade de Campinas (UNICAMP), SP (Brazil). Inst. de Quimica


    The aldol reaction is one of the most powerful and versatile methods for the construction of C-C bonds. Traditionally, this reaction was developed in a stoichiometric version; however, great efforts in the development of chiral catalysts for aldol reactions were performed in recent years. Thus, in this review article, the development of metal-mediated chiral catalysts in Mukaiyama-type aldol reaction, reductive aldol reaction and direct aldol reaction are discussed. Moreover, the application of these catalysts in the total synthesis of complex molecules is discussed. (author)

  14. Tribological properties of C/C-SiC composites for brake discs (United States)

    Jang, G. H.; Cho, K. H.; Park, S. B.; Lee, W. G.; Hong, U. S.; Jang, H.


    This study examines the friction and wear of ceramic matrix composites designed for use in automotive brake discs. The composites are produced by reinforcing a SiC matrix with carbon fibers using a liquid silicon infiltration method. C/C-SiC composites with two different compositions are fabricated to examine the compositional effect on the tribological properties. The tribological properties are evaluated using a scale dynamometer with a low-steel type friction material. The results show that the coefficient of friction is determined by the composition of the composite, which affects the propensity of friction film formation on the disc surface. A stable friction film on the disc surface also improves the wear resistance by diminishing the abrasive action of the disc. On the other hand, the friction film formation on the disc is affected by the applied pressure, and stable films are obtained at high pressures. This trend is prominent with discs with high Si content. However, both C/C/-SiC composites show superior performance in terms of the friction force oscillation, which is closely related to brake-induced vibration.

  15. Effect of Treated Graphite on Properties of Al2 O3-SiC-C Castables

    Institute of Scientific and Technical Information of China (English)

    SHI Huiying; ZHANG Yang; BU Xiangjuan; CAO Xiying; HE Jiasong; WANG Lei


    Al2O3-SiC-C castables with 2 % pitch or 2 %,4% and 6% treated graphite,respectively,were prepared based on the basic formulation of traditional Al2O3-SiC-C castables.The flowability of castables,and bulk density,volume stability,strength,oxidation resistance and slag resistance of specimens fired at 110 ℃,1 100 ℃ and 1 500 ℃ respectively were comparatively studied.The results showed that:(1) With carbon source changing from pitch to treated graphite and the increase of treated graphite addition,water addition of castables increased,bulk density of specimens fired at different temperatures increased firstly and then decreased,strength after drying decreased obviously,strength after firing and oxidation resistance changed slightly,hot modulus of rupture increased obviously;(2) Slag resistance of specimen with treated graphite was worse than that of specimen with the same amount of pitch,but the former was obviously improved with the increase of treated graphite addition.

  16. Benefits of X-Ray CMT for the modeling of C/C composites

    Energy Technology Data Exchange (ETDEWEB)

    Coindreau, Olivia; Lachaud, Jean; Vignoles, Gerard L. [LCTS - UMR 5801 CNRS-Universite Bordeaux 1-Safran-CEA 3, Allee La Boetie, Pessac, F33600 (France); Mulat, Christianne [LCTS - UMR 5801 CNRS-Universite Bordeaux 1-Safran-CEA 3, Allee La Boetie, Pessac, F33600 (France); IMS - UMR5218 CNRS-Universite Bordeaux 1-IPB 351, Avenue de la Liberation, Talence, F33410 (France); Germain, Christian [IMS - UMR5218 CNRS-Universite Bordeaux 1-IPB 351, Avenue de la Liberation, Talence, F33410 (France)


    C/C composites have application in very demanding areas like aerospace, fusion technology, etc. and thus their optimization is crucial, both in the control of processing routes and in the prediction of their behavior in use. Intense modeling efforts have been performed in these directions. To help a direct application on actual materials, with possibly complex reinforcement architectures, X-ray computerized micro-tomography (CMT) is a beneficial technique, since it allows producing extremely detailed representations of these architectures. However, there is a long way from the crude X-ray projections to the information that is directly usable in C/C composite modeling. This paper summarizes several achievements in this domain and discusses the obtained results, concerning (i) composites imaging by phase contrast CMT and holographic CMT, (ii) evaluation of effective geometrical and transfer properties in fiber arrangements and actual fiber-reinforced composites, (iii) modeling of degradation by ablation, and (iv) modeling of processing by chemical vapor infiltration. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  17. Molecular dynamics prediction of phonon-mediated thermal conductivity of f.c.c. Cu (United States)

    Evteev, Alexander V.; Momenzadeh, Leila; Levchenko, Elena V.; Belova, Irina V.; Murch, Graeme E.


    The phonon-mediated thermal conductivity of f.c.c. Cu is investigated in detail in the temperature range 40-1300 K. The calculations are performed in the framework of equilibrium molecular dynamics making use of the Green-Kubo formalism and one of the most reliable embedded-atom method potentials for Cu. It is found that the temporal decay of the heat current autocorrelation function (HCACF) of the Cu model at low and intermediate temperatures demonstrate a more complex behaviour than the two-stage decay observed previously for the f.c.c. Ar model. After the first stage of decay, it demonstrates a peak in the temperature range 40-800 K. A decomposition model of the HCACF is introduced. In the framework of that model we demonstrate that a classical description of the phonon thermal transport in the Cu model can be used down to around one quarter of the Debye temperature (about 90 K). Also, we find that above 300 K the thermal conductivity of the Cu model varies with temperature more rapidly than ?, following an exponent close to -1.4 in agreement with previous calculations on the Ar model. Phonon thermal conductivity of Cu is found to be about one order of magnitude higher than Ar. The phonon contribution to the total thermal conductivity of Cu can be estimated to be about 0.5% at 1300 K and about 10% at 90 K.

  18. Metal-catalyzed C-C bond cleavage in alkanes: effects of methyl substitution on transition-state structures and stability. (United States)

    Flaherty, David W; Hibbitts, David D; Iglesia, Enrique


    Methyl substituents at C-C bonds influence hydrogenolysis rates and selectivities of acyclic and cyclic C2-C8 alkanes on Ir, Rh, Ru, and Pt catalysts. C-C cleavage transition states form via equilibrated dehydrogenation steps that replace several C-H bonds with C-metal bonds, desorb H atoms (H*) from saturated surfaces, and form λ H2(g) molecules. Activation enthalpies (ΔH(‡)) and entropies (ΔS(‡)) and λ values for (3)C-(x)C cleavage are larger than for (2)C-(2)C or (2)C-(1)C bonds, irrespective of the composition of metal clusters or the cyclic/acyclic structure of the reactants. (3)C-(x)C bonds cleave through α,β,γ- or α,β,γ,δ-bound transition states, as indicated by the agreement between measured activation entropies and those estimated for such structures using statistical mechanics. In contrast, less substituted C-C bonds involve α,β-bound species with each C atom bound to several surface atoms. These α,β configurations weaken C-C bonds through back-donation to antibonding orbitals, but such configurations cannot form with (3)C atoms, which have one C-H bond and thus can form only one C-M bond. (3)C-(x)C cleavage involves attachment of other C atoms, which requires endothermic C-H activation and H* desorption steps that lead to larger ΔH(‡) values but also larger ΔS(‡) values (by forming more H2(g)) than for (2)C-(2)C and (2)C-(1)C bonds, irrespective of alkane size (C2-C8) or cyclic/acyclic structure. These data and their mechanistic interpretation indicate that low temperatures and high H2 pressures favor cleavage of less substituted C-C bonds and form more highly branched products from cyclic and acyclic alkanes. Such interpretations and catalytic consequences of substitution seem also relevant to C-X cleavage (X = S, N, O) in desulfurization, denitrogenation, and deoxygenation reactions.

  19. Would be the photon a composed particle? / Sobre a possibilidade da quantiza\\c{c}\\~ao dos fluxos de campo na radia\\c{c}\\~ao eletromagn\\'etica

    CERN Document Server

    Duarte, Celso de Araujo


    Here it is made a comparative analysis between the classical and the quantum expressions for the energy of electromagnetic radiation (ER). The comparison points to the possibility of the quantization of the magnetic and the electric field fluxes in the ER. ----- Apresenta-se uma an\\'alise comparativa entre as express\\~oes cl\\'assica e qu\\^antica para a energia da radia\\c{c}\\~ao eletromagn\\'etica (RE). A compara\\c{c}\\~ao nos aponta para a possibilidade de haver uma quantiza\\c{c}\\~ao dos fluxos dos campos magn\\'etico e el\\'etrico na RE.

  20. Preliminary Discussion on C/C++Program Design Course Teaching in Higher Vocational Colleges%浅谈高职院校C/C++程序设计课程教学

    Institute of Scientific and Technical Information of China (English)



    The C/C++program design is a basic course of computer specialty. The course is difficult to teach and learn, perplexes largeness teachers and students. Based on analyzing many years of teaching experience, summarizing the problems in the course of teaching, and drawing aged teachers’teaching views, the author puts forward some sugges-tions on C/C++program design teaching.%C/C++程序设计是计算机专业的一门基础课程,该课程难教、难学一直困扰着广大师生,根据多年的教学经验,总结自己在教学过程中存在的问题,听取老教师的教学观点,提出C/C++程序设计教学的几点建议。

  1. Facile P-C/C-H Bond-Cleavage Reactivity of Nickel Bis(diphosphine) Complexes. (United States)

    Zhang, Shaoguang; Li, Haixia; Appel, Aaron M; Hall, Michael B; Bullock, R Morris


    Unusual cleavage of P-C and C-H bonds of the P2 N2 ligand, in heteroleptic [Ni(P2 N2 )(diphosphine)](2+) complexes under mild conditions, results in the formation of an iminium formyl nickelate featuring a C,P,P-tridentate coordination mode. The structures of both the heteroleptic [Ni(P2 N2 )(diphosphine)](2+) complexes and the resulting iminium formyl nickelate have been characterized by NMR spectroscopy and single-crystal X-ray diffraction analysis. Density functional theory (DFT) calculations were employed to investigate the mechanism of the P-C/C-H bond cleavage, which involves C-H bond cleavage, hydride rotation, Ni-C/P-H bond formation, and P-C bond cleavage.

  2. Mesophase formation of coal-tar pitches used for impregnant of C/C composites

    Institute of Scientific and Technical Information of China (English)

    巩前明; 黄启忠; 黄伯云; 张福勤; 陈腾飞


    By a polarized light optical microscopy with a hot stage, liquid-phase nuclear magnetic resonance 13 C-NMR and 1 H-NMR, X-ray diffractometry and scanning electron microscopy (SEM), the factors that affect the formation of mesophase in C/C composites, such as pressure, quinoline insolubles (QI) and heterocylic compounds, were analyzed. Further, the graphitizability of the resultant carbon was discussed. The results indicate that to some degree, QI contents accelerate the formation of mesophase at atmospheric pressure; while at high pressure, the coalescence and growth of mesophase spherules are impeded and the resultant coke produced from higher QI content pitch is harder to be graphitized. This is in agreement with the transfer of microstructure from domain anisotropy to fine-grained mosaics.

  3. Architectural Visualization of C/C++ Source Code for Program Comprehension

    Energy Technology Data Exchange (ETDEWEB)

    Panas, T; Epperly, T W; Quinlan, D; Saebjornsen, A; Vuduc, R


    Structural and behavioral visualization of large-scale legacy systems to aid program comprehension is still a major challenge. The challenge is even greater when applications are implemented in flexible and expressive languages such as C and C++. In this paper, we consider visualization of static and dynamic aspects of large-scale scientific C/C++ applications. For our investigation, we reuse and integrate specialized analysis and visualization tools. Furthermore, we present a novel layout algorithm that permits a compressive architectural view of a large-scale software system. Our layout is unique in that it allows traditional program visualizations, i.e., graph structures, to be seen in relation to the application's file structure.

  4. Diffusion and electrotransport of some transition elements in (B. C. C. ) thorium

    Energy Technology Data Exchange (ETDEWEB)

    Okafor, I.C.I.


    Diffusion and electrotransport parameters of the transition elements molybdenum, rhenium, tungsten and zirconium in ..beta.. thorium were measured for the temperature range 1660-1945 K. For each solute element, except zirconium, the measurement was made at four different temperatures, where as for zirconium, studies were performed for only two temperatures 1770 and 1870 K. The authors' results indicate that all four solute elements migrate to the anode in b.c.c. thorium with mean Z/sup */ values of -6.6 for Mo, -4.6 for Re, -8.2 for W and about -2.5 for Zr. The results also indicate that molybdenum, rhenium and tungsten diffuse much faster in ..beta.. thorium than zirconium.

  5. Two Photon Transition Form Factor of $\\bar{c}c $ Quarkonia

    CERN Document Server

    Chen, Jing; Chang, Lei; Liu, Yu-xin


    The two photon transition of $\\bar{c}c$ quarkonia are studied within a covariant approach based on the consistent truncation scheme of the quantum chromodynamics Dyson-Schwinger equation for the quark propagator and the Bethe--Salpeter equation for the mesons. We find the decay widths of $\\eta_{c}^{} \\to \\gamma\\gamma$ and $\\chi_{c0,2}^{} \\to \\gamma\\gamma$ in good agreement with experimental data. The obtained transition form factor of $\\eta_{c}^{} \\to \\gamma\\gamma^{\\ast}$ for a wide range of space-like photon momentum transfer squared is also in agreement with the experimental findings of the BABAR experiment. As a by-product, the decay widths of $\\eta_{b}^{},\\chi_{b0,2}^{} \\to \\gamma\\gamma$ and the transition form factor of $\\eta_{b}^{}, \\chi_{c0,b0}^{} \\to\\gamma\\gamma^{\\ast}$ are predicted, which await for experimental test.

  6. The 3D Lima\\c{c}on: Properties and Applications

    CERN Document Server

    Kreismann, Jakob; Sinzinger, Stefan


    We perform electromagnetic wave simulations of fully three-dimensional optical Lima\\c{c}on-microcavities, one basis for their future applications in microlasers and photonic devices. The analysis of the three-dimensional modes and far-fields reveals an increase of the quality factors as compared to the two-dimensional case. The structure of the far-field in the third dimension shows pronounced maxima in the emission directionality inclined to the resonator plane which may be exploited for coupling the resonator modes to the environment. This triggers ideas for technical applications, like the suggested sensor that can detect small changes in the environment based on changes in the emission profile.

  7. Iron-Catalyzed C-C Cross-Couplings Using Organometallics. (United States)

    Guérinot, Amandine; Cossy, Janine


    Over the last decades, iron-catalyzed cross-couplings have emerged as an important tool for the formation of C-C bonds. A wide variety of alkenyl, aryl, and alkyl (pseudo)halides have been coupled to organometallic reagents, the most currently used being Grignard reagents. Particular attention has been devoted to the development of iron catalysts for the functionalization of alkyl halides that are generally challenging substrates in classical cross-couplings. The high functional group tolerance of iron-catalyzed cross-couplings has encouraged organic chemists to use them in the synthesis of bioactive compounds. Even if some points remain obscure, numerous studies have been carried out to investigate the mechanism of iron-catalyzed cross-coupling and several hypotheses have been proposed.

  8. Fabrication of SiC-C composite from poycarbosilane, epoxy and polyvinyl butyral resin mixture

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Jin Wook; Park, Dong Won; Jeun, Joon Pyo; Kang, Phil Hyun [Korea Atomic Energy Research Institte, Jeongeup (Korea, Republic of)


    Silicon carbide (SiC) has wide application in various industrial fields because of their good high strength and modulus, low density, oxidation resistance and thermal stability. In this study, SiC-C composites were prepared from mixture of polycarbosilane (PCS), epoxy resin, and polyvinyl butyral (PVB) with weight ration of 2/1/1. PCS/epoxy/PVB mixture was cured by electron beam irradiation at 5,000 kGy. The cured composite was pyrolyzed by heat treatment in flowing argon at 1,300 .deg. C for 1 hr. As the result of TGA analysis, the oxidation resistance showed 95.2% residue at 1,500 .deg. C under air.

  9. Influence of substitutional atoms on the Snoek peak of carbon in b.c.c. iron

    Energy Technology Data Exchange (ETDEWEB)

    Saitoh, Hajime; Yoshinaga, Naoki; Ushioda, Kohsaku


    The influence of substitutional atoms (Mn, P, Si, Al, Cr, Co) on the C Snoek peak in b.c.c. iron was investigated. In the dilute range of the substitutes, the addition of Co, Mn, Cr, Si, P and Al resulted in the decreases in Snoek peak height in this ascending order. However, the addition of Mn to the Fe-C-P alloy hardly changes Snoek peak height. There is even a case that Snoek peak height is increased by further Mn addition to this alloy. They can be explained systematically by the proposed model wherein the solute carbon present in the influence region where the lattice distortion around the substitute is greater than the threshold value cannot contribute to the Snoek peak. The strain field generated by a substitutional atom due to the difference in atomic size is concluded to be the main reason for the reduction in Snoek peak height.

  10. Sintering Behaviour of Al2O3-SiC-C Ramming Mix

    Institute of Scientific and Technical Information of China (English)

    WUXingrong; CAOFeng


    Silicon fines, boron acid solid powders and microfine SiO2 as sintering agents were incorporated into Al2O3-SiC-C ramming mix in order to investigated their effects on the microstructure , mechanical properties and sintering behavior of the ramming mix. Results show that all the three agents could improved both densification and mehanical properties markedly, compared to that of non-agent specimens and the effect of the composite of boron acid solid powders and microfine SiO2 is the best. The oxidation resistance increased with the addition of agents, which is supported by densification. Microstructures showed that agent powders could fill pores or produce liquid phases at high temperature, therefore, improve the sintering of the ramming mix.

  11. Sintering Behaviour of Al2O3-SiC-C Ramming Mix

    Institute of Scientific and Technical Information of China (English)

    WU Xingrong; CAO Feng


    Silicon fines, boron acid solid powders and microfine SiO2 as sintering agents were incorporated into Al2O3-SiC-C ramming mix in order to investigated their effects on the microstructue,mechanical properties and sintering be-havior of the ramming mix.Results show that all the three agents could improved both densification and mehanical properties markedly,compared to that of non-agent speci-mens and the effect of the composite of boron acid solid powders and microfine SiO2 is the best.The oxidation re-sistance increased with the addition of agents,which is supported by densification.Microstructures shoued that a-gent powders could fill pores or produce liquid phases at high temperatuer,therefore,improve the sintering of the ramming mix.

  12. Overview of C/C-SiC Composite Development for the Orion Launch Abort System (United States)

    Allen, Lee R.; Valentine, Peter G.; Schofield, Elizabeth S.; Beshears, Ronald D.; Coston, James E.


    Past and present efforts by the authors to further understanding of the ceramic matrix composite (CMC) material used in the valve components of the Orion Launch Abort System (LAS) Attitude Control Motor (ACM) will be presented. The LAS is designed to quickly lift the Orion Crew Exploration Vehicle (CEV) away from its launch vehicle in emergency abort scenarios. The ACM is a solid rocket motor which utilizes eight throttleable nozzles to maintain proper orientation of the CEV during abort operations. Launch abort systems have not been available for use by NASA on manned launches since the last Apollo ]Saturn launch in 1975. The CMC material, carbon-carbon/silicon-carbide (C/C-SiC), is manufactured by Fiber Materials, Inc. and consists of a rigid 4-directional carbon-fiber tow weave reinforced with a mixed carbon plus SiC matrix. Several valve and full system (8-valve) static motor tests have been conducted by the motor vendor. The culmination of these tests was the successful flight test of the Orion LAS Pad Abort One (PA ]1) vehicle on May 6, 2010. Due to the fast pace of the LAS development program, NASA Marshall Space Flight Center assisted the LAS community by performing a series of material and component evaluations using fired hardware from valve and full ]system development motor tests, and from the PA-1 flight ACM motor. Information will be presented on the structure of the C/C-SiC material, as well as the efficacy of various non ]destructive evaluation (NDE) techniques, including but not limited to: radiography, computed tomography, nanofocus computed tomography, and X-ray transmission microscopy. Examinations of the microstructure of the material via scanning electron microscopy and energy dispersive spectroscopy will also be discussed. The findings resulting from the subject effort are assisting the LAS Project in risk assessments and in possible modifications to the final ACM operational design.

  13. C,C'-bis(benzodiazaborolyl)dicarba-closo-dodecaboranes: synthesis, structures, photophysics and electrochemistry. (United States)

    Weber, Lothar; Kahlert, Jan; Brockhinke, Regina; Böhling, Lena; Halama, Johannes; Brockhinke, Andreas; Stammler, Hans-Georg; Neumann, Beate; Nervi, Carlo; Harder, Rachel A; Fox, Mark A


    Six new C,C'-bis(benzodiazaborolyl)dicarba-closo-dodecaboranes, 1,A-R2-1,A-C2B10H10, where R represents the group 2-(1,3-Et2-1,3,2-N2BC6H4) or 2-(1,3-Ph2-1,3,2-N2BC6H4) and A is 2, 7 or 12, were synthesized from o-, m-, and p-dicarbadodecaboranes (carboranes) by lithiation and subsequent treatment with the respective 2-bromo-1,3,2-benzodiazaboroles. UV-visible and fluorescence spectra of all carboranes display low energy charge transfer emissions. While such emissions with Stokes shifts between 17,330 and 21,290 cm(-1) are typical for C,C'-bis(aryl)-ortho-carboranes, the observed low-energy emissions with Stokes shifts between 8320 and 15,170 cm(-1) for the meta- and para-isomers are unusual as high-energy emissions are typical for meta- and para-dicarbadodecaboranes. Fluorescence quantum yields (φF) for the novel 1,7- and 1,12-bis(benzodiazaborolyl)-carboranes depend on the substituents at the nitrogen atoms of the heterocycle. Thus, the para-carborane with N-ethyl substituents 1,12-(1',3'-Et2-1',3',2'-N2BC6H4)2-1,12-C2B10H10 has a φF value of 41% in cyclohexane solution and only of 9% in the solid state, whereas the analogous 1,12-(1',3'-Ph2-1',3',2'-N2BC6H4)2-1,12-C2B10H10 shows quantum yields of 3% in cyclohexane solution and 72% in the solid state. X-ray crystallographic, computational and cyclic voltammetry studies for these carboranes are also presented.

  14. Electrophilic Pt(II) complexes: precision instruments for the initiation of transformations mediated by the cation-olefin reaction. (United States)

    Felix, Ryan J; Munro-Leighton, Colleen; Gagné, Michel R


    A discontinuity exists between the importance of the cation-olefin reaction as the principal C-C bond forming reaction in terpene biosynthesis and the synthetic tools for mimicking this reaction under catalyst control; that is, having the product identity, stereochemistry, and functionality under the control of a catalyst. The main reason for this deficiency is that the cation-olefin reaction starts with a reactive intermediate (a carbocation) that reacts exothermically with an alkene to reform the reactive intermediate; not to mention that reactive intermediates can also react in nonproductive fashions. In this Account, we detail our efforts to realize catalyst control over this most fundamental of reactions and thereby access steroid like compounds. Our story is organized around our progress in each component of the cascade reaction: the metal controlled electrophilic initiation, the propagation and termination of the cyclization (the cyclase phase), and the turnover deplatinating events. Electrophilic Pt(II) complexes efficiently initiate the cation-olefin reaction by first coordinating to the alkene with selection rules that favor less substituted alkenes over more substituted alkenes. In complex substrates with multiple alkenes, this preference ensures that the least substituted alkene is always the better ligand for the Pt(II) initiator, and consequently the site at which all electrophilic chemistry is initiated. This control element is invariant. With a suitably electron deficient ligand set, the catalyst then activates the coordinated alkene to intramolecular addition by a second alkene, which initiates the cation-olefin reaction cascade and generates an organometallic Pt(II)-alkyl. Deplatination by a range of mechanisms (β-H elimination, single electron oxidation, two-electron oxidation, etc.) provides an additional level of control that ultimately enables A-ring functionalizations that are orthogonal to the cyclase cascade. We particularly focus on

  15. Chemokine (C-C motif ligand 20, a potential biomarker for Graves' disease, is regulated by osteopontin.

    Directory of Open Access Journals (Sweden)

    Xiaoli Li

    Full Text Available CONTEXT: Graves' disease (GD is a common autoimmune disease involving the thyroid gland. The altered balance of pro- and anti-inflammatory cytokines plays an important role in the pathogenesis of GD. Chemokine (C-C motif ligand 20 (CCL20 is important for interleukin-17 (IL-17 signal activation and a potent chemoattractant for Th17 cells. Meanwhile, Osteopontin (OPN, a broadly expressed pleiotropic cytokine, has been implicated in GD through inducing Th1-involved response to enhance the production of proinflammatory cytokines and chemokines, but little is known about the role of OPN in regulating CCL20 and IL-17 signaling. OBJECTIVE: This study sought to explore the possibility of CCL20 level as a biomarker for GD, as well as investigate the role of OPN in regulating CCL20 production. METHODS: Fifty untreated GD patients, fifteen euthyroid GD patients, twelve TRAb-negative GD patients and thirty-five healthy control donors were recruited. OPN, CCL20 and other clinical GD diagnosis parameters were measured. CD4+T cells were isolated from peripheral blood mononuclear cells (PBMCs using antibody-coated magnetic beads. Enzyme-linked immune-sorbent assay and quantitative polymerase chain reaction were used to determine CCL20 expression level. RESULTS: We found that the plasma CCL20 level was enhanced in GD patients and decreased in euthyroid and TRAb-negative GD patients. In addition, CCL20 level correlated with GD clinical diagnostic parameters and plasma OPN level. Moreover, we demonstrated that recombinant OPN and plasma from untreated GD patients increased the expression of CCL20 in CD4+T cells, which could be blocked by OPN antibody. Furthermore, we found that the effect of OPN on CCL20 expression was mediated by β3 integrin receptor, IL-17, NF-κB and MAPK pathways. CONCLUSIONS: These results demonstrated that CCL20 might serve as a biomarker for GD and suggested the possible role of OPN in induction of CCL20 expression.

  16. New Concept of the Biosynthesis of 4-Alkyl-L-proline Precursors of Lincomycin, Hormaomycin and Pyrrolobenzodiazepines: Could a γ-Glutamyltransferase Cleave the C-C Bond?

    Directory of Open Access Journals (Sweden)

    Petra eJiraskova


    Full Text Available Structurally different and functionally diverse natural compounds – antitumour agents pyrrolo[1,4]benzodiazepines, bacterial hormone hormaomycin and lincosamide antibiotic lincomycin – share a common building unit, 4-alkyl-L-proline derivative (APD. APDs arise from L-tyrosine through a special biosynthetic pathway. Its generally accepted scheme, however, did not comply with current state of knowledge. Based on gene inactivation experiments and in vitro functional tests with recombinant enzymes, we designed a new APD biosynthetic scheme for the model of lincomycin biosynthesis. In the new scheme at least one characteristic in each of five final biosynthetic steps has been changed: the order of reactions, assignment of enzymes and/or reaction mechanisms. First, we demonstrate that LmbW methylates a different substrate than previously assumed. Second, we propose a unique reaction mechanism for the next step, in which a putative γ-glutamyltransferase LmbA indirectly cleaves off the oxalyl residue by transient attachment of glutamate to LmbW product. This unprecedented mechanism would represent the first example of the C-C bond cleavage catalyzed by a γ-glutamyltransferase, i.e., an enzyme that appears unsuitable for such activity. Finally, the inactivation experiments show that LmbX is an isomerase indicating that it transforms its substrate into a compound suitable for reduction by LmbY, thereby facilitating its subsequent complete conversion to APD 4-propyl-L-proline. Elucidation of the APD biosynthesis has long time resisted mainly due to the apparent absence of relevant C-C bond cleaving enzymatic activity. Our proposal aims to unblock this situation not only for lincomycin biosynthesis, but generally for all above mentioned groups of bioactive natural products with biotechnological potential.

  17. Pomegranate-like N,P-Doped Mo2C@C Nanospheres as Highly Active Electrocatalysts for Alkaline Hydrogen Evolution. (United States)

    Chen, Yu-Yun; Zhang, Yun; Jiang, Wen-Jie; Zhang, Xing; Dai, Zhihui; Wan, Li-Jun; Hu, Jin-Song


    Well-defined pomegranate-like N,P-doped Mo2C@C nanospheres were prepared by simply using phosphomolybdic acid (PMo12) to initiate the polymerization of polypyrrole (PPy) and as a single source for Mo and P to produce N,P-doped Mo2C nanocrystals. The existence of PMo12 at the molecular scale in the polymer network allows the formation of pomegranate-like Mo2C@C nanospheres with a porous carbon shell as peel and Mo2C nanocrystals well-dispersed in the N-doped carbon matrix as seeds. This nanostructure provides several favorable features for hydrogen evolution application: (1) the conductive carbon shell and matrix effectively prevent the aggregation of Mo2C nanocrystals and facilitate electron transportation; (2) the uniform N,P-doping in the carbon shell/matrix and plenty of Mo2C nanocrystals provide abundant catalytically highly active sites; and (3) nanoporous structure allows the effective exposure of active sites and mass transfer. Moreover, the uniform distribution of P and Mo from the single source of PMo12 and N from PPy in the polymeric PPy-PMo12 precursor guarantees the uniform N- and P-co-doping in both the graphitic carbon matrix and Mo2C nanocrystals, which contributes to the enhancement of electrocatalytic performance. As a result, the pomegranate-like Mo2C@C nanospheres exhibit extraordinary electrocatalytic activity for the hydrogen evolution reaction (HER) in terms of an extremely low overpotential of 47 mV at 10 mA cm(-2) in 1 M KOH, which is one of the best Mo-based HER catalysts. The strategy for preparing such nanostructures may open up opportunities for exploring low-cost high-performance electrocatalysts for various applications.

  18. Direct conversion of cellulose using carbon monoxide and water on a Pt-Mo2C/C catalyst

    KAUST Repository

    Li, Jing


    CO and H2O were employed as the hydrogen source for cellulose conversion to polyols. Pt-Mo2C/C tandem catalyst with the Pt-Mo 2C domain responsible for H2 and/or H production and the Pt-C domain for cellulose conversion was fabricated. Considerable polyols were obtained over this tandem Pt-Mo2C/C catalyst. This journal is © 2014 The Royal Society of Chemistry.

  19. Simulation of chemical vapor infiltration of propylene into C/C composites%丙烯CVI致密C/C复合材料的模拟研究

    Institute of Scientific and Technical Information of China (English)

    刘育太; 白瑞成; 李红; 张家宝; 任慕苏; 孙晋良


    Chemical vapor infiltration of propylene into C/C composites was studied by numeric simulation and an improved model for homogeneous gas-phase reactions of propylene pyrolysis was proposed. The model consists of 34 elementary reactions of 16 species. Then a bipore model for describing the changes of the pore topology with the progress of densification and a computer code for simulation of surface reactions by other authors were coupled together to predict the process. The numerical simulation showed that the density distribution of C/C composites is dependent on residence time of gas, densification temperature and densification time. There are two infiltration stages (rapid densification of micro-pores and successive densification of macro-pores) which act closely with the concentration distributions of main homogeneous pyrolytic products of propylene. Among them the concentration distribution of benzene seems most apparently to influence the densification speed and C/C density uniformity. The infiltration would be terminated when the benzene rich region becomes narrow, and the surface crusting of C/C appears. The present model is validated by comparing the predicted densities with the experimental ones.%通过模拟法对丙烯化学气相渗透(cvI)制备炭/炭复合材料(C/c)的工艺过程进行研究.基于16种反应物,建立了由34个基元反应组成的均相反应模型.引用双孔隙演化模型、非均相反应模型,对整个丙烯CVI模型进行耦合模拟.模拟结果表明,CVI法C/C复合材料的密度均匀性受沉积气体滞留时间、致密温度和致密时间等因素影响;致密化过程可分为微孔隙快速致密和大孔隙致密两个阶段,丙烯初级热解产物的浓度分布与这两个阶段关系密切;其中大分子气体苯的浓度分布对CVI沉积速度和C/C复合材料密度均匀性的影响明显,当苯浓度分布最高区严重变窄时,表明致密化过程结束,致密表面将出现结壳现象.验

  20. Simulation for F.C.C. deformation texture by modified pencil glide theory[Face Centered Cubic

    Energy Technology Data Exchange (ETDEWEB)

    Masui, H.


    Inspired by the pencil glide theory for b.c.c. metal, modified pencil glide theory for f.c.c. metal was proposed, dividing the 12 glide systems of f.c.c. metal into three groups individually composed of eight {l{underscore}brace}111{r{underscore}brace}{l{underscore}angle}110{r{underscore}angle} glide systems around the principal axes X[100], Y[010] and Z[001]. These assumptions yielded two mathematical solutions {Omega}(3) and {Omega}(1). In {Omega}(3), from the three groups with four complete conjugated glide systems composed of, respectively, two glide systems of common {l{underscore}angle}110{r{underscore}angle} direction, only one group with the maximum plastic work may operate if the requirements are satisfied, otherwise glide systems in {Omega}(1) where one of the four conjugated glide systems is zero are activated. The model considering the 12 glide systems of f.c.c. as a whole explained many experimentally stable orientations in axisymmetric and rolling deformation. The differences between the two pencil glide theories for b.c.c. and f.c.c. are also discussed with data.

  1. CYP719B1 is salutaridine synthase, the C-C phenol-coupling enzyme of morphine biosynthesis in opium poppy. (United States)

    Gesell, Andreas; Rolf, Megan; Ziegler, Jörg; Díaz Chávez, María Luisa; Huang, Fong-Chin; Kutchan, Toni M


    Morphine is a powerful analgesic natural product produced by the opium poppy Papaver somniferum. Although formal syntheses of this alkaloid have been reported, the morphine molecule contains five stereocenters and a C-C phenol linkage that to date render a total synthesis of morphine commercially unfeasible. The C-C phenol-coupling reaction along the biosynthetic pathway to morphine in opium poppy is catalyzed by the cytochrome P450-dependent oxygenase salutaridine synthase. We report herein on the identification of salutaridine synthase as a member of the CYP719 family of cytochromes P450 during a screen of recombinant cytochromes P450 of opium poppy functionally expressed in Spodoptera frugiperda Sf9 cells. Recombinant CYP719B1 is a highly stereo- and regioselective enzyme; of forty-one compounds tested as potential substrates, only (R)-reticuline and (R)-norreticuline resulted in formation of a product (salutaridine and norsalutaridine, respectively). To date, CYP719s have been characterized catalyzing only the formation of a methylenedioxy bridge in berberine biosynthesis (canadine synthase, CYP719A1) and in benzo[c]phenanthridine biosynthesis (stylopine synthase, CYP719A14). Previously identified phenol-coupling enzymes of plant alkaloid biosynthesis belong only to the CYP80 family of cytochromes. CYP719B1 therefore is the prototype for a new family of plant cytochromes P450 that catalyze formation of a phenol-couple.

  2. CYP96T1 of Narcissus sp. aff. pseudonarcissus Catalyzes Formation of the Para-Para' C-C Phenol Couple in the Amaryllidaceae Alkaloids (United States)

    Kilgore, Matthew B.; Augustin, Megan M.; May, Gregory D.; Crow, John A.; Kutchan, Toni M.


    The Amaryllidaceae alkaloids are a family of amino acid derived alkaloids with many biological activities; examples include haemanthamine, haemanthidine, galanthamine, lycorine, and maritidine. Central to the biosynthesis of the majority of these alkaloids is a C-C phenol-coupling reaction that can have para-para', para-ortho', or ortho-para' regiospecificity. Through comparative transcriptomics of Narcissus sp. aff. pseudonarcissus, Galanthus sp., and Galanthus elwesii we have identified a para-para' C-C phenol coupling cytochrome P450, CYP96T1, capable of forming the products (10bR,4aS)-noroxomaritidine and (10bS,4aR)-noroxomaritidine from 4′-O-methylnorbelladine. CYP96T1 was also shown to catalyzed formation of the para-ortho' phenol coupled product, N-demethylnarwedine, as less than 1% of the total product. CYP96T1 co-expresses with the previously characterized norbelladine 4′-O-methyltransferase. The discovery of CYP96T1 is of special interest because it catalyzes the first major branch in Amaryllidaceae alkaloid biosynthesis. CYP96T1 is also the first phenol-coupling enzyme characterized from a monocot. PMID:26941773

  3. CYP96T1 of Narcissus sp. aff. pseudonarcissus Catalyzes Formation of the Para-Para’ C-C Phenol Couple in the Amaryllidaceae Alkaloids

    Directory of Open Access Journals (Sweden)

    Matthew eKilgore


    Full Text Available The Amaryllidaceae alkaloids are a family of amino acid derived alkaloids with many biological activities; examples include haemanthamine, haemanthidine, galanthamine, lycorine, and maritidine. Central to the biosynthesis of the majority of these alkaloids is a C-C phenol-coupling reaction that can have para-para’, para-ortho’, or ortho-para’ regiospecificity. Through comparative transcriptomics of Narcissus sp. aff. pseudonarcissus, Galanthus sp., and Galanthus elwesii we have identified a para-para’ C-C phenol coupling cytochrome P450, CYP96T1, capable of forming the products (10bR,4aS-noroxomaritidine and (10bS,4aR-noroxomaritidine from 4’-O-methylnorbelladine. CYP96T1 was also shown to catalyzed formation of the para-ortho’ phenol coupled product, N-demethylnarwedine, as less than 1 % of the total product. CYP96T1 co-expresses with the previously characterized norbelladine 4’-O-methyltransferase. The discovery of CYP96T1 is of special interest because it catalyzes the first major branch in Amaryllidaceae alkaloid biosynthesis. CYP96T1 is also the first phenol-coupling enzyme characterized from a monocot.

  4. Mechanistic Insights on C-O and C-C Bond Activation and Hydrogen Insertion during Acetic Acid Hydrogenation Catalyzed by Ruthenium Clusters in Aqueous Medium

    Energy Technology Data Exchange (ETDEWEB)

    Shangguan, Junnan; Olarte, Mariefel V.; Chin, Ya-Huei [Cathy


    Catalytic pathways for acetic acid (CH3COOH) and hydrogen (H2) reactions on dispersed Ru clusters in the aqueous medium and the associated kinetic requirements for C-O and C-C bond cleavages and hydrogen insertion are established from rate and isotopic assessments. CH3COOH reacts with H2 in steps that either retain its carbon backbone and lead to ethanol, ethyl acetate, and ethane (47-95 %, 1-23 %, and 2-17 % carbon selectivities, respectively) or break its C-C bond and form methane (1-43 % carbon selectivities) at moderate temperatures (413-523 K) and H2 pressures (10-60 bar, 298 K). Initial CH3COOH activation is the kinetically relevant step, during which CH3C(O)-OH bond cleaves on a metal site pair at Ru cluster surfaces nearly saturated with adsorbed hydroxyl (OH*) and acetate (CH3COO*) intermediates, forming an adsorbed acetyl (CH3CO*) and hydroxyl (OH*) species. Acetic acid turnover rates increase proportionally with both H2 (10-60 bar) and CH3COOH concentrations at low CH3COOH concentrations (<0.83 M), but decrease from first to zero order as the CH3COOH concentration and the CH3COO* coverages increase and the vacant Ru sites concomitantly decrease. Beyond the initial CH3C(O)-OH bond activation, sequential H-insertions on the surface acetyl species (CH3CO*) lead to C2 products and their derivative (ethanol, ethane, and ethyl acetate) and the competitive C-C bond cleavage of CH3CO* causes the eventual methane formation. The instantaneous carbon selectivities towards C2 species (ethanol, ethane, and ethyl acetate) increase linearly with the concentration of proton-type Hδ+ (derived from carboxylic acid dissociation) and chemisorbed H*. The selectivities towards C2 products decrease with increasing temperature, because of higher observed barriers for C-C bond cleavage than H-insertion. This study offers an interpretation of mechanism and energetics and provides kinetic evidence of carboxylic acid assisted proton-type hydrogen (Hδ+) shuffling during H

  5. Migrating C/C++ Software to Mobile Platforms in the ADM Context

    Directory of Open Access Journals (Sweden)

    Liliana Martinez


    Full Text Available Software technology is constantly evolving and therefore the development of applications requires adapting software components and applications in order to be aligned to new paradigms such as Pervasive Computing, Cloud Computing and Internet of Things. In particular, many desktop software components need to be migrated to mobile technologies. This migration faces many challenges due to the proliferation of different mobile platforms. Developers usually make applications tailored for each type of device expending time and effort. As a result, new programming languages are emerging to integrate the native behaviors of the different platforms targeted in development projects. In this direction, the Haxe language allows writing mobile applications that target all major mobile platforms. Novel technical frameworks for information integration and tool interoperability such as Architecture-Driven Modernization (ADM proposed by the Object Management Group (OMG can help to manage a huge diversity of mobile technologies. The Architecture-Driven Modernization Task Force (ADMTF was formed to create specifications and promote industry consensus on the modernization of existing applications. In this work, we propose a migration process from C/C++ software to different mobile platforms that integrates ADM standards with Haxe. We exemplify the different steps of the process with a simple case study, the migration of “the Set of Mandelbrot” C++ application. The proposal was validated in Eclipse Modeling Framework considering that some of its tools and run-time environments are aligned with ADM standards.

  6. Human C-C chemokine receptor 3 monoclonal antibody inhibits pulmonary inflammation in allergic mice

    Institute of Scientific and Technical Information of China (English)

    Kai WANG; Hua-hao SHEN; Wen LI; Hua-qiong HUANG


    Aim:To evaluate the effect of C-C chemokine receptor 3 (CCR3) blockade on pulmonary inflammation and mucus production in allergic mice. Methods:We used the synthetic peptide of the CCR3 NH2-terminal as the immunizing antigen and generated murine monoclonal antibody against the human CCR3. In addition,the generated antibody was administered to mice sensitized and challenged with ovalbumin. The inflammatory cells in bronchoalveolar lavage,cytokine levels,pulmonary histopathology,and mucus secretion were examined. Results:The Western blotting analysis indicated that the generated antibody bound to CCR3 specifically. The allergic mice treated with the antihuman CCR3 antibody exhibited a significant reduction of pulmonary inflammation accompanied with the alteration of cytokine. Conclusion:The antibody we generated was specific to CCR3. The inhibition of airway inflammation and mucus overproduction by the antibody suggested that the blockade of CCR3 is an appealing therapeutical target for asthma. The present research may provide an experimental basis for the further study of this agent.

  7. Effect of infiltrating Si on friction properties of C/C composites

    Institute of Scientific and Technical Information of China (English)

    马运柱; 黄伯云; 熊翔; 肖鹏; 李江鸿; 黄启忠; 易茂忠


    In order to improve the friction-wear properties of the C/C composites for aircraft brake pairs, the fric-tion behavior of samples with infiltrating Si was investigated. The influence of Si smearing thickness on frictionproperties was studied in detail. The results show that with the increase of Si smearing thickness and β-SiC content,the friction coefficient reduces from 0.40 to 0.30; the linear wear of stators increases from 2.0 μm to 18.9 μm percycle, and that of rotors increases from 1.4 μm to 22.6 μm per cycle; mass wear of stators increases from 20.6 mgto 126.9 mg per cycle, and that of rotors increases from 13.7 mg to 166.2 mg per cycle. On the other hand, whena large number of inhomogeneous β-SiC particulates are performed, friction surfaces of the samples flake off layer bylayer and many nicks are observed.

  8. The Infiltration Process and Texture Transition of 2D C/C Composites

    Institute of Scientific and Technical Information of China (English)

    Hejun Li; Guozhong Xu; Kezhi Li; Chuang Wang; Wei Li; Miaoling Li


    2D needle-punched fiber felt was infiltrated by a kind of rapid isothermal chemical vapor infiltration technique. The infiltration process and texture transition of the infiltrated C/C composites were investigated. The porosity and the variations of the cumulative pore volume were determined by mercury porosimetry. The texture of matrix carbon was studied under a polarized light microscope. The results show that the relative mass gain of the sample increases directly as the infiltration time at the initial stage until 20 h, and subsequently the increasing rate of the relative mass gain decreases gradually with the prolonging of infiltration time. Three layers of pyrocarbon were formed around fibers. Low-textured pyrocarbon was obtained at the initial stage. With the densification going on, high-textured pyrocarbon was formed on the surface of low-textured pyrocarbon. Then, low-textured pyrocarbon was produced again during the final stage of densification. The texture transition is ascribed to the variation of the ratio of cumulative inner surface area to volume of pores and the gas partial pressure in pores.

  9. Study of {lambda} hyperon production in C+C collisions at 2 AGeV beam energy with the HADES spectrometer

    Energy Technology Data Exchange (ETDEWEB)

    Kanaki, K.


    The HADES spectrometer is a high resolution detector installed at the SIS/GSI, Darmstadt. It was primarily designed for studying dielectron decay channels of vector mesons. However, its high accuracy capabilities make it an attractive tool for investigating other rare probes at these beam energies, like strange baryons. Development and investigation of Multiwire Drift Chambers for high spatial resolution have been provided. One of the early experimental runs of HADES was analyzed and the {lambda} hyperon signal was successfully reconstructed for the first time in C+C collisions at 2 AGeV beam kinetic energy. The total {lambda} production cross section is contrasted with expectations from simulations and compared with measurements of the {lambda} yield in heavier systems at the same energy. In addition, the result is considered in the context of strangeness balance and the relative strangeness content of the reaction products is determined. (orig.)

  10. Selective scission of C-O and C-C bonds in ethanol using bimetal catalysts for the preferential growth of semiconducting SWNT arrays. (United States)

    Zhang, Shuchen; Hu, Yue; Wu, Juanxia; Liu, Dan; Kang, Lixing; Zhao, Qiuchen; Zhang, Jin


    For the application of single-walled carbon nanotubes (SWNTs) to electronic and optoelectronic devices, techniques to obtain semiconducting SWNT (s-SWNT) arrays are still in their infancy. We have developed herein a rational approach for the preferential growth of horizontally aligned s-SWNT arrays on a ST-cut quartz surface through the selective scission of C-O and C-C bonds of ethanol using bimetal catalysts, such as Cu/Ru, Cu/Pd, and Au/Pd. For a common carbon source, ethanol, a reforming reaction occurs on Cu or Au upon C-C bond breakage and produces C(ads) and CO, while a deoxygenating reaction occurs on Ru or Pd through C-O bond breaking resulting in the production of O(ads) and C2H4. The produced C2H4 by Ru or Pd can weaken the oxidative environment through decomposition and the neutralization of O(ads). When the bimetal catalysts with an appropriate ratio were used, the produced C(ads) and C2H4 can be used as carbon source for SWNT growth, and O(ads) promotes a suitable and durable oxidative environment to inhibit the formation of metallic SWNTs (m-SWNTs). Finally, we successfully obtained horizontally aligned SWNTs on a ST-cut quartz surface with a density of 4-8 tubes/μm and an s-SWNT ratio of about 93% using an Au/Pd (1:1) catalyst. The synergistic effects in bimetallic catalysts provide a new mechanism to control the growth of s-SWNTs.

  11. A Numerical Study on the Thermal Conductivity of 3D Woven C/C Composites at High Temperature (United States)

    Shigang, Ai; Rujie, He; Yongmao, Pei


    Experimental data for Carbon/Carbon (C/C) constituent materials are combined with a three dimensional steady state heat transfer finite element analysis to demonstrate the average in-plane and out-of-plane thermal conductivities (TCs) of C/C composites. The finite element analysis is carried out at two distinct length scales: (a) a micro scale comparable with the diameter of carbon fibres and (b) a meso scale comparable with the carbon fibre yarns. Micro-scale model calculate the TCs at the fibre yarn scale in the three orthogonal directions ( x, y and z). The output results from the micro-scale model are then incorporated in the meso-scale model to obtain the global TCs of the 3D C/C composite. The simulation results are quite consistent with the theoretical and experimental counterparts reported in references. Based on the numerical approach, TCs of the 3D C/C composite are calculated from 300 to 2500 K. Particular attention is given in elucidating the variations of the TCs with temperature. The multi-scale models provide an efficient approach to predict the TCs of 3D textile materials, which is helpful for the thermodynamic property analysis and structure design of the C/C composites.

  12. Amide-directed photoredox-catalysed C-C bond formation at unactivated sp3 C-H bonds (United States)

    Chu, John C. K.; Rovis, Tomislav


    Carbon-carbon (C-C) bond formation is paramount in the synthesis of biologically relevant molecules, modern synthetic materials and commodity chemicals such as fuels and lubricants. Traditionally, the presence of a functional group is required at the site of C-C bond formation. Strategies that allow C-C bond formation at inert carbon-hydrogen (C-H) bonds enable access to molecules that would otherwise be inaccessible and the development of more efficient syntheses of complex molecules. Here we report a method for the formation of C-C bonds by directed cleavage of traditionally non-reactive C-H bonds and their subsequent coupling with readily available alkenes. Our methodology allows for amide-directed selective C-C bond formation at unactivated sp3 C-H bonds in molecules that contain many such bonds that are seemingly indistinguishable. Selectivity arises through a relayed photoredox-catalysed oxidation of a nitrogen-hydrogen bond. We anticipate that our findings will serve as a starting point for functionalization at inert C-H bonds through a strategy involving hydrogen-atom transfer.

  13. GCC(g++)编译环境下C(C++)和汇编的接口分析%C/C++ Language and Assemble Language Ombination Programming Based on Linux

    Institute of Scientific and Technical Information of China (English)

    郝丽花; 陈付龙



  14. C-C chemokine receptor-7 mediated endocytosis of antibody cargoes into intact cells

    Directory of Open Access Journals (Sweden)

    Xavier eCharest-Morin


    Full Text Available The C-C chemokine receptor-7 (CCR7 is a G protein coupled receptor that has a role in leukocyte homing, but that is also expressed in aggressive tumor cells. Preclinical research supports that CCR7 is a valid target in oncology. In view of the increasing availability of therapeutic monoclonal antibodies that carry cytotoxic cargoes, we studied the feasibility of forcing intact cells to internalize known monoclonal antibodies by exploiting the cycle of endocytosis and recycling triggered by the CCR7 agonist CCL19. Firstly, an anti-CCR7 antibody (CD197; clone 150503 labeled surface recombinant CCR7 expressed in intact HEK 293a cells and the fluorescent antibody was internalized following CCL19 treatment. Secondly, a recombinant myc-tagged CCL19 construction was exploited along the anti-myc monoclonal antibody 4A6. The myc-tagged ligand was produced as a conditioned medium of transfected HEK 293a cells that contained the equivalent of 430 ng/ml of immunoreactive CCL19 (average value, ELISA determination. CCL19-myc, but not authentic CCL19, carried the fluorophore-labeled antibody 4A6 into other recipient cells that expressed recombinant CCR7 (microscopy, cytofluorometry. The immune complexes were apparent in endosomal structures, colocalized well with the small GTPase Rab5 and progressed toward Rab7-positive endosomes. A dominant negative form of Rab5 (GDP-locked inhibited this endocytosis. Further, endosomes in CCL19-myc- or CCL19-stimulated cells were positive for β-arrestin2, but rarely for β-arrestin1. Following treatment with CCL19-myc and the 4A6 antibody, the melanoma cell line A375 that expresses endogenous CCR7 was specifically stained using a secondary peroxidase-conjugated antibody. Agonist-stimulated CCR7 can transport antibody-based cargoes, with possible therapeutic applications in oncology.

  15. Empirical Force Fields for Mechanistic Studies of Chemical Reactions in Proteins. (United States)

    Das, A K; Meuwly, M


    Following chemical reactions in atomistic detail is one of the most challenging aspects of current computational approaches to chemistry. In this chapter the application of adiabatic reactive MD (ARMD) and its multistate version (MS-ARMD) are discussed. Both methods allow to study bond-breaking and bond-forming processes in chemical and biological processes. Particular emphasis is put on practical aspects for applying the methods to investigate the dynamics of chemical reactions. The chapter closes with an outlook of possible generalizations of the methods discussed.

  16. Cloning and expression analysis of human reticulon 4c cDNA

    Institute of Scientific and Technical Information of China (English)


    RTNs (reticulons) is a gene family related to the growth and differentiation of neuroendocrine cell. This family is composed of several members such as RTN1, RTN2 and RTN3. RTN1 and RTN2 have been proved to have 3 transcripts with different length. Because the RTN1c cDNA was involved in the sologenesis of small cell lung carcinoma (SCLC), it was selected as a bioinformatic probe to clone novel members of RTN family with the electric hybridization assistant new-gene cloning method (EHAC). A 1677-bp cDNA was identified from human brain cDNA library. The cDNA contains an intact open reading frame (ORF) which encodes a protein of 199 amino acids. This deduced protein is highly homologous to RTN1c, RTN2c and RTN3 with identities of 64.4%, 45.8% and 50.0% respectively. This new gene was named RTN4c (GenBank accession number: AF087901). Northern hybridization showed that the full length of RTN4c transcript is about 1.8 kb. It is hardly expressed in heart, placenta, lung, spleen, thymus, testis, ovary, small intestine and peripheral blood white cells; but it is highly expressed in the tissues of skeletal muscle, brain, liver and kidney, and less expressed in the pancreas, prostate and colon. Furthermore, Northern results also showed that there is a 2.3 kb transcript expressed in 14 tissues except liver and skeletal muscle; while another 5.0 kb transcript in brain, skeletal muscle and testis. By the electric hybridization walking, we obtained two full-length contigs with a length of 4632 and 2235 bp respectively. The former encodes a protein with 1192 amino acids and was defined as RTN4a; the latter encodes another protein with 373 amino acids, and was named RTN4b. The RTN4 gene was mapped to human chromosome 2p14-p13 region by the radiation hybridization (RH).

  17. A domino palladium-catalyzed C-C and C-O bonds formation via dual O-H bond activation: synthesis of 6,6-dialkyl-6H-benzo[c]chromenes. (United States)

    Mahendar, Lodi; Krishna, Jonnada; Reddy, Alavala Gopi Krishna; Ramulu, Bokka Venkat; Satyanarayana, Gedu


    An efficient Pd-catalyzed domino reaction of α,α-dialkyl-(2-bromoaryl)methanols to 6,6-dialkyl-6H-benzo[c]chromenes is presented. Their formation can be explained via a five membered Pd(II)-cycle that efficiently involves a domino homocoupling with the second molecule, β-carbon cleavage, and finally intramolecular Buchwald-Hartwig cyclization. This domino process effectively involves breaking of five σ-bonds (2C-Br, 2O-H, and a C-C) and formation of two new σ-bonds (C-C and C-O). This mechanistic pathway is unprecedented and further illustrates the power of transition metal catalysis.

  18. Computer Simulation of the E.C.C.S. Buckling Curve using a Monte-Carlo Method

    NARCIS (Netherlands)

    Strating, J.; Vos, H.


    The application of a Monte-Carlo simulation procedure to obtain the distribution function of the maximum load of a hinged column with imperfections is discussed. Buckling tests carried out by the E.C.C.S. on IPE 160 sections have been simulated. Information concerning the column variables is obtaine

  19. Highly Conductive, Mechanically Robust, and Electrochemically Inactive TiC/C Nanofiber Scaffold for High-Performance Silicon Anode Batteries

    KAUST Repository

    Yao, Yan


    Silicon has a high specific capacity of 4200 mAh/g as lithium-ion battery anodes, but its rapid capacity fading due to >300% volume expansion and pulverization presents a significant challenge for practical applications. Here we report a core-shell TiC/C/Si inactive/active nanocomposite for Si anodes demonstrating high specific capacity and excellent electrochemical cycling. The amorphous silicon layer serves as the active material to store Li+, while the inactive TiC/C nanofibers act as a conductive and mechanically robust scaffold for electron transport during the Li-Si alloying process. The core-shell TiC/C/Si nanocomposite anode shows ∼3000 mAh g-1 discharge capacity and 92% capacity retention after 100 charge/discharge cycles. The excellent cycling stability and high rate performance could be attributed to the tapering of the nanofibers and the open structure that allows facile Li ion transport and the high conductivity and mechanical stability of the TiC/C scaffold. © 2011 American Chemical Society.

  20. Synthesis and systematic evaluation of symmetric sulfonated centrally C-C bonded cyanine near-infrared dyes for protein labelling

    NARCIS (Netherlands)

    Wal, Van Der Steffen; Kuil, Joeri; Valentijn, A.R.P.M.; Leeuwen, Van Fijs W.B.


    The most commonly used near-infrared cyanine dyes contain an aryl ether that is not fully stable towards nucleophiles. Replacement of the aryl ether by a more stable carbon-carbon bond can improve the stability. In this work we have synthesized a series of four negatively-charged symmetrical C-C

  1. Acid and base catalyzed Davis-Beirut reaction: experimental and theoretical mechanistic studies and synthesis of novel 3-amino-2H-indazoles. (United States)

    Avila, Belem; El-Dakdouki, Mohammad H; Nazer, Musa Z; Harrison, Jason G; Tantillo, Dean J; Haddadin, Makhluf J; Kurth, Mark J


    The Davis-Beirut reaction, which provides an efficient synthesis of 2H-indazoles and, subsequently, indazolones, is shown to proceed rapidly from o-nitrosobenzaldehyde and primary amines under both acid or base catalysis. Experimental and theoretical evidence in support of a reaction mechanism is provided in which o-nitrosobenzylidine imine is a pivotal intermediate in this N,N-bond forming heterocyclization reaction. The Davis-Beirut reaction is also shown to effectively synthesize a number of novel 3-amino-2H-indazole derivatives.

  2. Influence of adding Ti on molten NiAl intermetallic infiltration into C/C composites%添加Ti对C/C复合材料渗NiAl金属间化合物的影响

    Institute of Scientific and Technical Information of China (English)

    於广军; 肖鹏; 方华婵


    通过铺展实验研究添加Ti对NiAl金属间化合物与C/C复合材料润湿性的影响,发现添加Ti元素可改善熔融NiAl与C/C复合材料基体的润湿性。以低密度C/C复合材料为坯体,采用真空熔渗法制备C/C-NiAl复合材料,利用X射线衍射(XRD)和扫描电镜(SEM)对材料进行分析。结果表明:添加的Ti粉含量(质量分数)为15%时,C/C复合材料熔渗NiAl金属间化合物的效果最佳,且TiC颗粒与NiAl熔体在C/C复合材料内部呈网状分布;渗NiAl后材料的密度从1.35 g/cm3提高到2.47 g/cm3,开孔率从27%下降到15.1%,沿平行纤维排布面方向的洛氏硬度较未渗NiAl的C/C复合材料提高约30.7%。添加Ti能改善C/C复合材料渗NiAl性能的主要原因是Ti与C反应形成的TiC改善了NiAl在C/C复合材料中的化学吸附和物理吸附特性。%The influence of adding titanium on the wettability of molten NiAl intermetallic on the surface of C/C composites was investigated by spreading experiment. It is indicated that adding Ti can improve the wettability between C/C composites and NiAl intermetallic. Using the low-density C/C composite perform the C/C-NiAl composites were prepared by the vacuum molten infiltration. The composites were analyzed by X-ray diffraction(XRD) and scanning electronic microscope(SEM). The results show that NiAl with about 15%Ti (mass fraction) possesses good wettability on the surface of C/C composites. The TiC particles and NiAl melt present network distribution in C/C composites internal. The density increases from 1.35 g/cm3 to 2.47 g/cm3 while the porosity decreases from 27%to 15.1%after the infiltration of NiAl. On the other hand, the Rockwell hardness of C/C-NiAl composites increases by 30.7%in the direction parallel to fiber fabric plane compared with that of C/C composites. The improvement of adding Ti for molten NiAl infiltration into the C/C composites results from the improvement of the chemical and physical adsorption

  3. C/C++代码自动生成脚本语言接口的实现%Implementation of Automatic Generating Scripting Language Interfaces with C/C++ Code

    Institute of Scientific and Technical Information of China (English)

    官尚元; 张芝萍; 徐立锋; 缪敬



  4. Statically Detecting Likely Buffer Overflow Vulnerabilities in C/C++ Program%C/C++源程序缓冲区溢出漏洞的静态检测

    Institute of Scientific and Technical Information of China (English)

    杨小龙; 刘坚



  5. Deep Analysis and Application of the Function Pointer in the C/C++ Language Programming%C/C++语言中函数指针的深入分析与应用

    Institute of Scientific and Technical Information of China (English)




  6. A quantum informational approach for dissecting chemical reactions

    CERN Document Server

    Duperrouzel, Corinne; Boguslawski, Katharina; Barcza, Gergerly; Legeza, Örs; Ayers, Paul W


    We present a conceptionally different approach to dissect bond-formation processes in metal-driven catalysis using concepts from quantum information theory. Our method uses the entanglement and correlation among molecular orbitals to analyze changes in electronic structure that accompany chemical processes. As a proof-of-principle example, the evolution of nickel-ethene bond-formation is dissected which allows us to monitor the interplay of back-bonding and $\\pi$-donation along the reaction coordinate. Furthermore, the reaction pathway of nickel-ethene complexation is analyzed using quantum chemistry methods revealing the presence of a transition state. Our study supports the crucial role of metal-to-ligand back-donation in the bond-forming process of nickel-ethene.

  7. Asymmetric Organocatalytic Reactions of α,β-Unsaturated Cyclic Ketones

    Directory of Open Access Journals (Sweden)

    Giuseppe Bartoli


    Full Text Available The 1,4-conjugate addition of nucleophiles to α,β-unsaturated carbonyl compounds represents one fundamental bond-forming reaction in organic synthesis. The development of effective organocatalysts for the enantioselective conjugate addition of malonate, nitroalkane and other carbon and heteroatom nucleophiles to cycloenones constitutes an important research field and has been explored in recent years. At the same time, asymmetric Diels-Alder reactions have been developed and often a mechanism has been demonstrated to be a double addition rather than synchronous. This review aims to cover literature up to the end of 2010, describing all the different organocatalytic asymmetric 1,4-conjugate additions even if they are listed as transfer hydrogenation, cycloadditions or desymmetrization of aromatic compounds.

  8. Single-molecule chemical reactions on DNA origami

    DEFF Research Database (Denmark)

    Voigt, Niels Vinther; Tørring, Thomas; Rotaru, Alexandru


    as templates for building materials with new functional properties. Relatively large nanocomponents such as nanoparticles and biomolecules can also be integrated into DNA nanostructures and imaged. Here, we show that chemical reactions with single molecules can be performed and imaged at a local position...... on a DNA origami scaffold by atomic force microscopy. The high yields and chemoselectivities of successive cleavage and bond-forming reactions observed in these experiments demonstrate the feasibility of post-assembly chemical modification of DNA nanostructures and their potential use as locally......DNA nanotechnology and particularly DNA origami, in which long, single-stranded DNA molecules are folded into predetermined shapes, can be used to form complex self-assembled nanostructures. Although DNA itself has limited chemical, optical or electronic functionality, DNA nanostructures can serve...

  9. Ethane C-C clumping in natural gas : a proxy for cracking processes ? (United States)

    Clog, M. D.; Ferreira, A. A.; Santos Neto, E. V.; Eiler, J. M.


    Ethane (C2H6) is the second-most abundant alkane in most natural gas reservoirs, and is used to produce ethylene for petrochemical industries. It is arguably the simplest molecule that can manifest multiple 13C substitutions. There are several plausible controls on ∆13C2H6in natural gas: thermodynamically controlled homogeneous isotope exchange reactions analogous to those behind carbonate clumped isotope thermometry; inheritance from larger biomolecules that undergo thermal degradation to produce natural gas; mixing of natural gases that differ markedly in bulk isotopic composition; diffusive fractionation; or combinations of these and/or other, less expected fractionations. There is little basis for predicting which of these will control isotopic variations among natural ethanes, but we think it likely that addition of this new isotopic proxy will reveal new insights into the natural chemistry of ethane. We have developed a method to measure the abundance of 13C2H6 in natural samples, using high-resolution mass spectrometry. We define ∆13C2H6 as 1000 . ((13C2H6/12C2H6)measured/(13C2H6/12C2H6)stochastic -1). We studied several suites of natural gas samples and experimentally produced or modified ethane. Natural ethanes, including closely related samples from a single natural gas field, exhibit surprisingly large ranges in ∆13C2H6 (4 ‰ overall; up to 3 ‰ in one gas field). Such ranges cannot be explained by thermodynamic equilibrium at a range of different temperatures, or by diffusive fractionation. Kinetic isotope effects associated with 'cracking' reactions, and/or inheritance of non-equilibrium carbon isotope structures from source organics are more likely causes. We observe a correlation between ∆13C2H6 and the concentration of alkanes other than methane in several suites of natural gases, suggesting the causes of clumped isotope variations are tied to the controls on gas wetness. An experiment examining ethane residual to high

  10. ANP T2238C, C-664G Gene Polymorphism and Coronary Heart Diseasein Chinese Population

    Institute of Scientific and Technical Information of China (English)

    ZHANG Liyun; CHENG Longxian; HE Meian; HU Binchang; WU Tangchun


    The association between atrial natriuretic peptide (ANP) polymorphism and coronary heart disease (CHD) was studied in Chinese population. The genotypes of ANP T2238C and ANP C-664G were detected by polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP) methods in 158 consecutive CHD patients and 165 controls. It was found that the distribution of A2A2 genotype in CHD group was significantly higher than that in control group (P<0.05). Stepwise Logistic regression analysis revealed that male, smoking, history of hypertension,history of diabetes, family history of hypertension, high level of serum cholesterol, and ANP T2238C polymorphism were the possible risk factors in patients with CHD (P<0.05). However, there was no significant difference between the patients with CHD and the control group in the distribution of ANP C-664G polymorphism (P>0.05). The results suggest that A2A2 T2238C genotype could be one of the risk factors for CHD (P<0.05, OR: 1.80, 95% CI:1.03-3.15).

  11. 将Python嵌入到C/C++应用程序中的编程方法

    Institute of Scientific and Technical Information of China (English)




  12. Predicting the Dielectric Strength of c-C4F8 and SF6 Gas Mixtures by Monte Carlo Method

    Institute of Scientific and Technical Information of China (English)

    WU Bian-tao; XIAO Deng-ming


    An improved Monte Carlo method was used to simulate the motion of electrons in c-C4F8 and SF6 gas mixtures for pulsed townsend discharge. The electron swarm parameters such as effective ionization coefficient, (-α) and drift velocity over the E/N range from 280~700 Td(1Td= 10-21 V·m2) were calculated by employing a set of cross sections available in literature. From the variation cure of (-α) with SF6 partial pressure p, the limiting field (E/N)lim of gas mixture at different gas content was determined. It is found that the limiting field of c-C4F8 and SF6gas mixture is higher than that of pure SF6 at any SF6 mixture ratio. Simulation results show excellent agreement with experiment data available in previous literature.

  13. Application of Sol Self-Clean Bonded Al2O3-SiC-C Castable for Iron Runner

    Institute of Scientific and Technical Information of China (English)

    XU Guotao; ZHANG Honglei; CHEN Huasheng; WANG Yue; LI Huaiyuan; XIONG Yafei


    The properties and microstructure of sol self-clean bonded Al2O3-SiC-C castable in iron runner were studied, and the relation between the amount of sol selfclean binder and the properties of castable were discussed. It is believed that the addition of sol self-clean binder can improve the compressive strength, but has little effect on the bulk density and the apparent porosity,which enable the castable to be applicable in different conditions.

  14. Spheroidization behavior of dendritic b.c.c. phase in Zr-based モ-phase composite

    Directory of Open Access Journals (Sweden)

    Sun Guoyuan


    Full Text Available The spheroidization behavior of the dendritic b.c.c. phase dispersed in a bulk metallic glass (BMG matrix was investigated through applying semi-solid isothermal processing and a subsequent rapid quenching procedure to a Zr-based モ-phase composite. The Zr-based composite with the composition of Zr56.2Ti13.8Nb5.0Cu6.9Ni5.6Be12.5 was prefabricated by a water-cooled copper mold-casting method and characterized by X-ray diffraction (XRD and scanning electron microscope (SEM. The results show that the composite consists of a glassy matrix and uniformly distributed fine dendrites of the モ-Zr solid solution with the body-centered-cubic (b.c.c. structure. Based on the differential scanning calorimeter (DSC examination results, and in view of the b.c.c. モ-Zr to h.c.p. メ-Zr phase transition temperature, a semi-solid holding temperature of 900 ìC was determined. After reheating the prefabricated composite to the semi-solid temperature, followed by an isothermal holding process at this temperature for 5 min, and then quenching the semi-solid mixture into iced-water; the two-phase microstructure composed of a BMG matrix and uniformly dispersed spherical b.c.c. モ-Zr particles with a high degree of sphericity was achieved. The present spheroidization transition is a thermodynamically autonomic behavior, and essentially a diffusion process controlled by kinetic factors; and the formation of the BMG matrix should be attributed to the rapid quenching of the semi-solid mixture as well as the large glass-forming ability of the remaining melt in the semi-solid mixture.

  15. 76 FR 39254 - Airworthiness Directives; Schweizer Aircraft Corporation (Schweizer) Model 269A, A-1, B, C, C-1... (United States)


    ... Corporation (Schweizer) Model 269A, A-1, B, C, C-1, and TH-55 Series Helicopters AGENCY: Federal Aviation... reviewed Schweizer Service Bulletins No. B-295 for Model 269A, A-1, B, and C helicopters, and No. C1B-032... continues to read as follows: Authority: 49 U.S.C. 106(g), 40113, 44701. Sec. 39.13 0 2. The FAA amends...

  16. Search for the weak decays J/psi -> D-s(()*()-) e(+)nu(e) + c.c.

    NARCIS (Netherlands)

    Ablikim, M.; Achasov, M. N.; Ai, X. C.; Albayrak, O.; Albrecht, M.; Ambrose, D. J.; Amoroso, A.; An, F. F.; An, Q.; Bai, J. Z.; Ferroli, R. Baldini; Ban, Y.; Bennett, D. W.; Bennett, J. V.; Bertani, M.; Bettoni, D.; Bian, J. M.; Bianchi, F.; Boger, E.; Bondarenko, O.; Boyko, I.; Briere, R. A.; Cai, H.; Cai, X.; Cakir, O.; Calcaterra, A.; Cao, G. F.; Cetin, S. A.; Chang, J. F.; Chelkov, G.; Chen, G.; Chen, H. S.; Chen, H. Y.; Chen, J. C.; Chen, M. L.; Chen, S. J.; Chen, X.; Chen, X. R.; Chen, Y. B.; Cheng, H. P.; Chu, X. K.; Chu, Y. P.; Cibinetto, G.; Cronin-Hennessy, D.; Dai, H. L.; Dai, J. P.; Dedovich, D.; Deng, Z. Y.; Denig, A.; Denysenko, I.; Destefanis, M.; De Mori, F.; Ding, Y.; Dong, C.; Dong, J.; Dong, L. Y.; Dong, M. Y.; Du, S. X.; Duan, P. F.; Fan, J. Z.; Fang, J.; Fang, S. S.; Fang, X.; Fang, Y.; Fava, L.; Feldbauer, F.; Felici, G.; Feng, C. Q.; Fioravanti, E.; Fu, C. D.; Gao, Q.; Gao, Y.; Garzia, I.; Goetzen, K.; Gong, W. X.; Gradl, W.; Greco, M.; Gu, M. H.; Gu, Y. T.; Guan, Y. H.; Guo, A. Q.; Guo, L. B.; Guo, T.; Guo, Y.; Guo, Y. P.; Haddadi, Z.; Hafner, A.; Han, S; Han, Y. L.; Harris, F. A.; He, K. L.; He, Z. Y.; Held, T.; Heng, Y. K.; Hou, Z. L.; Hu, C.; Hu, H. M.; Hu, J. F.; Hu, T.; Hu, Y.; Huang, G. M.; Huang, G. S.; Huang, H. P.; Huang, J. S.; Huang, X. T.; Huang, Y.; Hussain, T.; Ji, Q.; Ji, Q. P.; Ji, X. B.; Ji, X. L.; Jiang, L. L.; Jiang, L. W.; Jiang, X. S.; Jiao, J. B.; Jiao, Z.; Jin, D. P.; Jin, S.; Johansson, T.; Julin, A.; Kalantar-Nayestanaki, N.; Kang, X. L.; Kang, X. S.; Kavatsyuk, M.; Ke, B. C.; Kliemt, R.; Kloss, B.; Kolcu, O. B.; Kopf, B.; Kornicer, M.; Kuehn, W.; Kupsc, A.; Lai, W.; Lange, J. S.; Lara, M.; Larin, P.; Li, C. H.; Li, Cheng; Li, D. M.; Li, F.; Li, G.; Li, H. B.; Li, J. C.; Li, Jin; Li, K.; Li, K.; Li, P. R.; Li, T.; Li, W. D.; Li, W. G.; Li, X. L.; Li, X. M.; Li, X. N.; Li, X. Q.; Li, Z. B.; Liang, H.; Liang, Y. F.; Liang, Y. T.; Liao, G. R.; Lin, D. X.; Liu, B. J.; Liu, C. L.; Liu, C. X.; Liu, F. H.; Liu, Fang; Liu, Feng; Liu, H. B.; Liu, H. H.; Liu, H. H.; Liu, H. M.; Liu, J.; Liu, J. P.; Liu, J. Y.; Liu, K.; Liu, K. Y.; Liu, L. D.; Liu, Q.; Liu, S. B.; Liu, X.; Liu, X. X.; Liu, Y. B.; Liu, Z. A.; Liu, Zhiqiang; Liu, Zhiqing; Loehner, H.; Lou, X. C.; Lu, H. J.; Lu, J. G.; Lu, R. Q.; Lu, Y.; Lu, Y. P.; Luo, C. L.; Luo, M. X.; Luo, T.; Luo, X. L.; Lv, M.; Lyu, X. R.; Ma, F. C.; Ma, H. L.; Ma, L. L.; Ma, Q. M.; Ma, S.; Ma, T.; Ma, X. N.; Ma, X. Y.; Maas, F. E.; Maggiora, M.; Malik, Q. A.; Mao, Y. J.; Mao, Z. P.; Marcello, S.; Messchendorp, J. G.; Min, J.; Min, T. J.; Mitchell, R. E.; Mo, X. H.; Mo, Y. J.; Moeini, H.; Morales, C. Morales; Moriya, K.; Muchnoi, N. Yu.; Muramatsu, H.; Nefedov, Y.; Nerling, F.; Nikolaev, I. B.; Ning, Z.; Nisar, S.; Niu, S. L.; Niu, X. Y.; Olsen, S. L.; Ouyang, Q.; Pacetti, S.; Patteri, P.; Pelizaeus, M.; Peng, H. P.; Peters, K.; Ping, J. L.; Ping, R. G.; Poling, R.; Pu, Y. N.; Qi, M.; Qian, S.; Qiao, C. F.; Qin, L. Q.; Qin, N.; Qin, X. S.; Qin, Y.; Qin, Z. H.; Qiu, J. F.; Rashid, K. H.; Redmer, C. F.; Ren, H. L.; Ripka, M.; Rong, G.; Ruan, X. D.; Santoro, V.; Sarantsev, A.; Savrie, M.; Schoenning, K.; Schumann, S.; Shan, W.; Shao, M.; Shen, C. P.; Shen, P. X.; Shen, X. Y.; Sheng, H. Y.; Shepherd, M. R.; Song, W. M.; Song, X. Y.; Sosio, S.; Spataro, S.; Spruck, B.; Sun, G. X.; Sun, J. F.; Sun, S. S.; Sun, Y. J.; Sun, Y. Z.; Sun, Z. J.; Sun, Z. T.; Tang, C. J.; Tang, X.; Tapan, I.; Thorndike, E. H.; Tiemens, M.; Toth, D.; Ullrich, M.; Uman, I.; Varner, G. S.; Wang, B.; Wang, B. L.; Wang, D.; Wang, D. Y.; Wang, K.; Wang, L. L.; Wang, L. S.; Wang, M.; Wang, P.; Wang, P. L.; Wang, Q. J.; Wang, S. G.; Wang, W.; Wang, X. F.; Wang, Y. D.; Wang, Y. F.; Wang, Y. Q.; Wang, Z.; Wang, Z. G.; Wang, Z. H.; Wang, Z. Y.; Wei, D. H.; Wei, J. B.; Weidenkaff, P.; Wen, S. P.; Wiedner, U.; Wolke, M.; Wu, L. H.; Wu, Z.; Xia, L. G.; Xia, Y.; Xiao, D.; Xiao, Z. J.; Xie, Y. G.; Xiu, Q. L.; Xu, G. F.; Xu, L.; Xu, Q. J.; Xu, Q. N.; Xu, X. P.; Yan, L.; Yan, W. B.; Yan, W. C.; Yan, Y. H.; Yang, H. X.; Yang, L.; Yang, Y.; Yang, Y. X.; Ye, H.; Ye, M.; Ye, M. H.; Yin, J. H.; Yu, B. X.; Yu, C. X.; Yu, H. W.; Yu, J. S.; Yuan, C. Z.; Yuan, W. L.; Yuan, Y.; Yuncu, A.; Zafar, A. A.; Zallo, A.; Zeng, Y.; Zhang, B. X.; Zhang, B. Y.; Zhang, C.; Zhang, C. C.; Zhang, D. H.; Zhang, H. H.; Zhang, H. Y.; Zhang, J. J.; Zhang, J. L.; Zhang, J. Q.; Zhang, J. W.; Zhang, J. Y.; Zhang, J. Z.; Zhang, K.; Zhang, L.; Zhang, S. H.; Zhang, X. J.; Zhang, X. Y.; Zhang, Y.; Zhang, Y. H.; Zhang, Z. H.; Zhang, Z. P.; Zhang, Z. Y.; Zhao, G.; Zhao, J. W.; Zhao, J. Y.; Zhao, J. Z.; Zhao, Lei; Zhao, Ling; Zhao, M. G.; Zhao, Q.; Zhao, Q. W.; Zhao, S. J.; Zhao, T. C.; Zhao, Y. B.; Zhao, Z. G.; Zhemchugov, A.; Zheng, B.; Zheng, J. P.; Zheng, W. J.; Zheng, Y. H.; Zhong, B.; Zhou, L.; Zhou, Li; Zhou, X.; Zhou, X. K.; Zhou, X. R.; Zhou, X. Y.; Zhu, K.; Zhu, K. J.; Zhu, S.; Zhu, X. L.; Zhu, Y. C.; Zhu, Y. S.; Zhu, Z. A.; Zhuang, J.; Zou, B. S.; Zou, J. H.


    Using a sample of 2.25 x 10(8) J/psi events collected with the BESIII detector at the BEPCII collider, we search for the J/psi semileptonic weak decay J/psi -> D-s(-) e(+)nu(e) +c.c. with a much higher sensitivity than previous searches. We also perform the first search for J/psi -> D-s(*-) e(+) nu(

  17. Transfer Hydrogenation of C= C Double Bonds Catalyzed by Ruthenium Amido-Complexes:Scopes, Limitation and Enantioselectivity

    Institute of Scientific and Technical Information of China (English)

    XUE,Dong; CHENG,Ying-Chun; CUI,Xin; WANG,Qi-Wei; ZHU,Jin; DENG,Jin-Gen


    @@ The reduction of C = C double bonds is one of the most fundamental synthetic transformations and plays a key role in the manufacturing of a wide variety of bulk and fine chemicals. Hydrogenation of olefinic substrates can be achieved readily with molecular hydrogen in many cases, but transfer hydrogenation methods using suitable donor molecules such as formic acid or alcohols are receiving increasing attention as possible synthetic alternatives because it requires no special equipment and avoids the handling of potentially hazardous gaseous hydrogen.

  18. The use of ultrasmall iron(0) nanoparticles as catalysts for the selective hydrogenation of unsaturated C-C bonds. (United States)

    Kelsen, Vinciane; Wendt, Bianca; Werkmeister, Svenja; Junge, Kathrin; Beller, Matthias; Chaudret, Bruno


    The performance of well-defined ultrasmall iron(0) nanoparticles (NPs) as catalysts for the selective hydrogenation of unsaturated C-C and C=X bonds is reported. Monodisperse iron nanoparticles of about 2 nm size are synthesized by the decomposition of {Fe(N[Si(CH3)3]2)2}2 under dihydrogen. They are found to be active for the hydrogenation of various alkenes and alkynes under mild conditions and weakly active for C=O bond hydrogenation.

  19. Effects of Preform Density on Structure and Property of C/C-SiC Composites Fabricated by Gaseous Silicon Infiltration

    Directory of Open Access Journals (Sweden)

    CAO Yu


    Full Text Available The 3-D needled C/C preforms with different densities deposited by chemical vapor infiltration (CVI method were used to fabricate C/C-SiC composites by gaseous silicon infiltration (GSI. The porosity and CVI C thickness of the preforms were studied, and the effects of preform density on the mechanical and thermal properties of C/C-SiC composites were analyzed. The results show that with the increase of preform density, the preform porosity decreases and the CVI C thickness increases from several hundred nanometers to several microns. For the C/C-SiC composites, as the preform density increases, the residual C content increases while the density and residual Si content decreases. The SiC content first keeps at a high level of about 40% (volume fraction, which then quickly reduces. Meanwhile, the mechanical properties increase to the highest values when the preform density is 1.085g/cm3, with the flexure strength up to 308.31MP and fracture toughness up to 11.36MPa·m1/2, which then decrease as the preform density further increases. The thermal conductivity and CTE of the composites, however, decrease with the increase of preform density. It is found that when the preform porosity is too high, sufficient infiltration channels lead to more residual Si, and thinner CVI C thickness results in the severe corrosion of the reinforcing fibers by Si and lower mechanical properties. When the preform porosity is relatively low, the contents of Si and SiC quickly reduce since the infiltration channels are rapidly blocked, resulting in the formation of large closed pores and not high mechanical properties.

  20. Cu6Sn5-TiC-C nanocomposite anodes for high-performance sodium-ion batteries (United States)

    Kim, Il Tae; Allcorn, Eric; Manthiram, Arumugam


    Cu6Sn5 alloy nanoparticles dispersed in a TiC and C conductive matrix have been developed via high energy mechanical milling (HEMM), and the resulting Cu6Sn5-TiC-C nanocomposite has been assessed as anodes for sodium-ion batteries. Composite anodes of Sn-C exhibit poor cyclic performance even with the introduction of 2 vol. % fluoroethylene carbonate (FEC) additive into the electrolyte. In contrast, Cu6Sn5-TiC-C nanocomposite anodes exhibit stable cycle life corresponding to a capacity retention of ∼80% at 40 cycles and high-rate performance with a capacity retention of ∼62% at 3000 mA g-1. These superior performance metrics is ascribed to the well-developed electrochemically active nanocrystalline material (Cu6Sn5) as well as a hybrid conductive matrix (TiC and C). The incorporation of 2 vol. % FEC additive into the electrolyte further improves the performance of Cu6Sn5-TiC-C nanocomposite to display a capacity retention of ∼94% at 250 cycles and high-rate capacity retention of ∼82% at 5000 mA g-1, which are attributed to the formation of a thin and stable SEI layer in presence of FEC.

  1. A method of quantitative characterization for the component of C/C composites based on the PLM video (United States)

    Li, Y. X.; Qi, L. H.; Song, Y. S.; Li, H. J.


    PLM video is used for studying the microstructure of C/C composites, because it contains the structure and motion information at the same time. It means that PLM video could provide more comprehensive microstructure features of C/C composites, and then the microstructure could be quantitatively characterized by image processing. However, several unavoidable displacements still exist in the PLM video, which could occur during the process of image acquisition. Therefore, an image registration method was put forward to correct the displacements by the phase correlation, and further to achieve the quantitative characterization of component combined with image fusion and threshold segmentation based on the PLM video of C/C composites. Specifically, PLM video was decomposed to a frame sequence firstly. Then a series of processes was carried out on this basis, including selecting the frame as equal interval, segmenting the static and dynamic regions and correcting the relative displacements between the adjacent frames. Meanwhile, the result of image registration was verified through image fusion, and it indicates that the proposed method could eliminate the displacements effectively. Finally, some operations of image processing were used to segment the components and calculate their fractions, thus the quantitative calculation was achieved successfully.

  2. Phenomenological description of a three-center insertion reaction: an information-theoretic study. (United States)

    Esquivel, Rodolfo O; Flores-Gallegos, Nelson; Dehesa, Jesús S; Angulo, Juan Carlos; Antolín, Juan; López-Rosa, Sheila; Sen, K D


    Information-theoretic measures are employed to describe the course of a three-center chemical reaction in terms of detecting the transition state and the stationary points unfolding the bond-forming and bond-breaking regions which are not revealed in the energy profile. The information entropy profiles for the selected reactions are generated by following the intrinsic-reaction-coordinate (IRC) path calculated at the MP2 level of theory from which Shannon entropies in position and momentum spaces at the QCISD(T)/6-311++G(3df,2p) level are determined. Several complementary reactivity descriptors are also determined, such as the dipole moment, the molecular electrostatic potential (MEP) obtained through a multipole expansion (DMA), the atomic charges and electric potentials fitted to the MEP, the hardness and softness DFT descriptors, and several geometrical parameters which support the information-theoretic analysis. New density-based structures related to the bond-forming and bond-breaking regions are proposed. Our results support the concept of a continuum of transient of Zewail and Polanyi for the transition state rather than a single state, which is also in agreement with reaction-force analyses.

  3. 27 CFR 28.64 - Bond, Form 2737. (United States)


    ... provided in § 28.51, a continuing bond on Form 2737 (5110.67). The bond shall be executed in a penal sum... wines which may remain unaccounted for at any one time: Provided, That the maximum penal sum of such bond shall not exceed $200,000, but in no case shall the penal sum be less than $1,000....

  4. Reaction Graph

    Institute of Scientific and Technical Information of China (English)



    The paper proposes reaction graphs as graphical representations of computational objects.A reaction graph is a directed graph with all its arrows and some of its nodes labeled.Computations are modled by graph rewriting of a simple nature.The basic rewriting rules embody the essence of both the communications among processes and cut-eliminations in proofs.Calculi of graphs are ideentified to give a formal and algebraic account of reaction graphs in the spirit of process algebra.With the help of the calculi,it is demonstrated that reaction graphs capture many interesting aspects of computations.

  5. Effectiveness of Diffusion Barrier Coatings for Mo-Re Embedded in C/SiC and C/C (United States)

    Glass, David E.; Shenoy, Ravi N.; Wang, Zeng-Mei; Halbig, Michael C.


    Advanced high-temperature cooling applications may often require the elevated-temperature capability of carbon/silicon carbide or carbon/carbon composites in combination with the hermetic capability of metallic tubes. In this paper, the effects of C/SiC and C/C on tubes fabricated from several different refractory metals were evaluated. Though Mo, Nb, and Re were evaluated in the present study, the primary effort was directed toward two alloys of Mo-Re, namely, arc cast Mo-41Re and powder metallurgy Mo-47.5Re. Samples of these refractory metals were subjected to either the PyC/SiC deposition or embedding in C/C. MoSi2(Ge), R512E, and TiB2 coatings were included on several of the samples as potential diffusion barriers. The effects of the processing and thermal exposure on the samples were evaluated by conducting burst tests, microhardness surveys, and scanning electron microscopic examination (using either secondary electron or back scattered electron imaging and energy dispersive spectroscopy). The results showed that a layer of brittle Mo-carbide formed on the substrates of both the uncoated Mo-41Re and the uncoated Mo-47.5Re, subsequent to the C/C or the PyC/SiC processing. Both the R512E and the MoSi2(Ge) coatings were effective in preventing not only the diffusion of C into the Mo-Re substrate, but also the formation of the Mo-carbides. However, none of the coatings were effective at preventing both C and Si diffusion without some degradation of the substrate.

  6. 基于C & C08-Q的UniCenter2013中间层的设计与实现%Design and implementation of UniCenter2013 intermediate layer based on C & C08-Q

    Institute of Scientific and Technical Information of China (English)



    基于C&C08-Q的UniCenter2013呼叫中心项目,将强大的互联网同固定电话网统一起来,为客户提供了一个功能完备且全天候服务的客户中心。中间层是整个呼叫中心系统构建中的基础模块,本文为用户提供了一个完善的数据库访问解决方案,从而增强了系统的扩展性和可维护性。%The UniCenter2013 Call Center project is based on C&C08-Q,integrating powerful Internet and fixed telephone network,providing a feature complete and all whether service customer center.The intermediate layer is the basic module in the whole call center system, this chapter providing a perfect solution for accessing the database,so enhanced the system extensibility and maintainability.

  7. Method 446.0: In Vitro Determination of Chlorophylls a, b, c + c and Pheopigments in 1 2Marine And Freshwater Algae by Visible Spectrophotometry (United States)

    This method provides a procedure for determination of chlorophylls a (chl a), b (chl b), c + c 1 2 (chl c + c ) and pheopigments of chlorophyll a (pheo a) 1 2 found in marine and freshwater phytoplankton. Chlorophyllide a is determined as chl a. Visible wavelength spectrophotomet...

  8. The Academic and Remedial Placement of Students Entering B. C. C. in September 1975 by Curriculum Group. Research Report BCC-9-75. (United States)

    Bronx Community Coll., NY.

    This report describes the Bronx Community College (B.C.C.) freshmen class entering in September 1975, in terms of high school grade average and scores on reading-English and mathematics placement tests. As of the fall of 1974, B.C.C. enrolled a markedly higher proportion of students with high school averages below 70 percent than any other college…

  9. Dielectron Production in C+C Collisions at 1 GeV/u and the Solution to the DLS Puzzle

    CERN Document Server

    Pachmayer, Y C; Agodi, C; Balanda, A; Bellia, G; Belver, D; Belyaev, A; Blanco, A; Bhömer, M; Boyard, J L; Braun-Munzinger, P; Cabanelas, P; Castro, oE; Chernenko, S; Christ, T; Destefanis, M; Daz, J; Dohrmann, F; Dybczak, A; Eberl, T; Fabbietti, L; Fateev, O; Finocchiaro, P; Fonte, Paulo J R; Friese, J; Fröhlich, I; Galatyuk, T; Garzn, J A; Gernhuser, R; Gil, A; Gilardi, C; Golubeva, M; Gonzalez-Diaz, D; Grosse, E; Guber, F; Heilmann, M; Hennino, T; Holzmann, R; Ierusalimov, A; Iori, I; Ivashkin, A; Jurkovic, M; Kmpfer, B; Kanaki, K; Karavicheva, T; Kirschner, D; König, I; König, W; Kolb, B W; Kotte, R; Kozuch, A; Krsa, A; Krizek, F; Krücken, R; Kühn, W; Kugler, A; Kurepin, A; Lamas-Valverde, J; Lang, S; Lange, J S; Lapidus, K; Lopes, L; Lorenz, M; Maier, L; Mangiarotti, A; Marn, J; Markert, J; Metag, V; Michalska, B; Michel, J; Mishra, D; Moriniere, E; Mousa, J; Müntz, C; Naumann, Lutz; Novotny, R; Otwinowski, J; Palka, M; Parpottas, Y; Pechenov, V; Pechenova, O; Prez Cavalcanti, T; Pietraszko, J; Przygoda, W; Ramstein, B; Reshetin, A; Roy-Stephan, M; Rustamov, A; Sadovskii, A; Sailer, B; Salabura, P; Schmah, A; Simon, R; Sobolev, Yu G; Spataro, S; Spruck, B; Strbele, H; Stroth, J; Sturm, C; Sudol, M; Tarantola, A; Teilab, K; Tlustý, P; Traxler, M; Trebacz, R; Tsertos, H; Veretenkin, I; Wagner, V; Wen, H; Wisniowski, M; Wojcik, T; Wüstenfeld, J; Yurevich, S; Zanevsky, Y; Zhou, P; Zumbruch, P


    The production of e+e- pairs in C+C collisions at 1 GeV/u was investigated with the HADES experiment at GSI, Darmstadt. In the invariant-mass region $ 0.15\\: GeV/c^{2} \\leq M_{ee} \\leq 0.5\\: GeV/c^{2}$ the measured pair yield shows a strong excess above the contribution expected from hadron decays after freeze-out. The data are in good agreement with the results of the former DLS experiment for the same system and energy.


    Institute of Scientific and Technical Information of China (English)

    X.G. Luan; L.F. Cheng; S.R. Qiao; J. Zhang


    The samples made from a SiC-C/SiC composite were pretreated in Ar under creep,fatigue, creep and fatigue interaction, as well as in dry oxygen and wet oxygen under fatigue at 1300℃ for 15 hours. The fracture behaviors of the pretreated samples were investigated at 1300℃. The loading-strain curves and the microstructures of the sample were compared with each other. The various of high temperature tensile behaviors was attributed to the different microstructures resulted from different high temperature pretreatments.

  11. Numerical modelling of micro-machining of f.c.c. single crystal: Influence of strain gradients

    KAUST Repository

    Demiral, Murat


    A micro-machining process becomes increasingly important with the continuous miniaturization of components used in various fields from military to civilian applications. To characterise underlying micromechanics, a 3D finite-element model of orthogonal micro-machining of f.c.c. single crystal copper was developed. The model was implemented in a commercial software ABAQUS/Explicit employing a user-defined subroutine VUMAT. Strain-gradient crystal-plasticity and conventional crystal-plasticity theories were used to demonstrate the influence of pre-existing and evolved strain gradients on the cutting process for different combinations of crystal orientations and cutting directions. Crown Copyright © 2014.

  12. Bonding and Integration of C-C Composite to Cu-Clad-Molybdenum for Thermal Management Applications (United States)

    Asthana, R.; Singh, M.; Shpargel, T.P.


    Two- and three-dimensional carbon-carbon composites with either resin-derived matrix or CVI matrix were joined to Cu-clad-Mo using active Ag-Cu braze alloys for thermal management applications. The joint microstructure and composition were examined using Field-Emission Scanning Electron Microscopy and Energy-Dispersive Spectroscopy, and the joint hardness was characterized using the Knoop microhardness testing. Observations on the infiltration of the composite with molten braze, dissolution of metal substrate, and solute segregation at the C-C surface have been discussed. The thermal response of the integrated assembly is also briefly discussed.

  13. Measurement of low-mass e{sup +}e{sup -} pair production in 2 AGeV C-C collisions with HADES

    Energy Technology Data Exchange (ETDEWEB)

    Sudol, Malgorzata


    The search for a modification of hadron properties inside nuclear matter at normal and/or high temperature and density is one of the most interesting issues of modern nuclear physics. Dilepton experiments, give insight into the properties of strong interaction and the nature of hadron mass generation. One of these research tools is the HADES spectrometer. HADES is a high acceptance dilepton spectrometer installed at the heavy-ion synchrotron (SIS) at GSI, Darmstadt. The main physics motivation of HADES is the measurement of e{sup +}e{sup -} pairs in the invariant-mass range up to 1 GeV/c{sup 2} in pion- and proton-induced reactions, as well as in heavy-ion collisions. The goal is to investigate the properties of the vector mesons {rho}, {omega} and of other hadrons reconstructed from e{sup +}e{sup -} decay pairs. Dileptons are penetrating probes allowing to study the in-medium properties of hadrons. However, the measurement of such dilepton pairs is difficult because of a very large background from other processes in which leptons are created. This thesis presents the analysis of the data provided by the first physics run with the HADES spectrometer. For the first time e{sup +}e{sup -} pairs produced in C+C collisions at an incident energy of 2 GeV per nucleon have been collected with sufficient statistics. This experiment is of particular importance since it allows to address the puzzling pair excess measured by the former DLS experiment at a beam energy 1.04 AGeV. The thesis consists of five chapters. The first chapter presents the physics case which is addressed in the work. In the second chapter the HADES spectrometer is introduced with the characteristic of specific detectors which are part of the spectrometer. Chapter three focusses on the issue of charged-particle identification. The fourth chapter discusses the reconstruction of the di-electron spectra in C+C collisions. In this part of the thesis a comparison with theoretical models is included as well

  14. Diversification of ortho-Fused Cycloocta-2,5-dien-1-one Cores and Eight- to Six-Ring Conversion by σ Bond C-C Cleavage. (United States)

    Eccleshare, Lee; Lozada-Rodríguez, Leticia; Cooper, Phillippa; Burroughs, Laurence; Ritchie, John; Lewis, William; Woodward, Simon


    Sequential treatment of 2-C6 H4 Br(CHO) with LiC≡CR(1) (R(1) =SiMe3 , tBu), nBuLi, CuBr⋅SMe2 and HC≡CCHClR(2) [R(2) =Ph, 4-CF3 Ph, 3-CNPh, 4-(MeO2 C)Ph] at -50 °C leads to formation of an intermediate carbanion (Z)-1,2-C6 H4 {CA (=O)C≡CB R(1) }{CH=CH(CH(-) )R(2) } (4). Low temperatures (-50 °C) favour attack at CB leading to kinetic formation of 6,8-bicycles containing non-classical C-carbanion enolates (5). Higher temperatures (-10 °C to ambient) and electron-deficient R(2) favour retro σ-bond C-C cleavage regenerating 4, which subsequently closes on CA providing 6,6-bicyclic alkoxides (6). Computational modelling (CBS-QB3) indicated that both pathways are viable and of similar energies. Reaction of 6 with H(+) gave 1,2-dihydronaphthalen-1-ols, or under dehydrating conditions, 2-aryl-1-alkynylnaphthlenes. Enolates 5 react in situ with: H2 O, D2 O, I2 , allylbromide, S2 Me2 , CO2 and lead to the expected C-E derivatives (E=H, D, I, allyl, SMe, CO2 H) in 49-64 % yield directly from intermediate 5. The parents (E=H; R(1) =SiMe3 , tBu; R(2) =Ph) are versatile starting materials for NaBH4 and Grignard C=O additions, desilylation (when R(1) =SiMe) and oxime formation. The latter allows formation of 6,9-bicyclics via Beckmann rearrangement. The 6,8-ring iodides are suitable Suzuki precursors for Pd-catalysed C-C coupling (81-87 %), whereas the carboxylic acids readily form amides under T3P® conditions (71-95 %).

  15. Tandem Catalysis Utilizing Olefin Metathesis Reactions. (United States)

    Zieliński, Grzegorz K; Grela, Karol


    Since olefin metathesis transformation has become a favored synthetic tool in organic synthesis, more and more distinct non-metathetical reactions of alkylidene ruthenium complexes have been developed. Depending on the conditions applied, the same olefin metathesis catalysts can efficiently promote isomerization reactions, hydrogenation of C=C double bonds, oxidation reactions, and many others. Importantly, these transformations can be carried out in tandem with olefin metathesis reactions. Through addition of one portion of a catalyst, a tandem process provides structurally advanced products from relatively simple substrates without the need for isolation of the intermediates. These aspects not only make tandem catalysis very attractive from a practical point of view, but also open new avenues in (retro)synthetic planning. However, in the literature, the term "tandem process" is sometimes used improperly to describe other types of multi-reaction sequences. In this Concept, a number of examples of tandem catalysis involving olefin metathesis are discussed with an emphasis on their synthetic value.

  16. Chemokine (C-C motif ligand 2 mediates direct and indirect fibrotic responses in human and murine cultured fibrocytes

    Directory of Open Access Journals (Sweden)

    Ekert Jason E


    Full Text Available Abstract Background Fibrocytes are a population of circulating bone-marrow-derived cells that express surface markers for leukocytes and mesenchymal cells, and are capable of differentiating into myofibroblasts. They have been observed at sites of active fibrosis and increased circulating numbers correlate with mortality in idiopathic pulmonary fibrosis (IPF. Inhibition of chemokine (C-C motif receptor 2 (CCR2 during experimental models of lung fibrosis reduces lung collagen deposition, as well as reducing lung fibrocyte accumulation. The aim of the present study was to determine whether human and mouse fibrocytes express functional CCR2. Results Following optimized and identical human and murine fibrocyte isolation, both cell sources were shown to be positive for CCR2 by flow cytometry and this expression colocalized with collagen I and CD45. Human blood fibrocytes stimulated with the CCR2 ligand chemokine (C-C motif ligand 2 (CCL2, demonstrated increased proliferation (P P P Conclusions This study directly compares the functional responses of human and murine fibrocytes to CCR2 ligands, and following comparable isolation techniques. We have shown comparable biological effects, strengthening the translatability of the murine models to human disease with respect to targeting the CCR2 axis to ameliorate disease in IPF patients.

  17. Shear and Flexural Behaviour of R.C.C. Beam With Circular Opening Strengthened By CFRP Sheets

    Directory of Open Access Journals (Sweden)



    Full Text Available This paper explores the behavior of R.C.C. beam with circular opening strengthened by CFRP sheets. In this experimental work five beams were casted, one beam without opening (i.e. solid beam and one with circular post opening and considered as control beams. The remaining three beams were externally strengthened by Carbon fiber reinforced polymer (CFRP sheets with different strengthening schemes i.e. around the opening, inside the opening. These beams were simply supported and tested less than two points loading in the loading frame. The behaviors of such beams were studied in terms of load carrying capacity, load-deflection behavior and cracking patterns. From the test results it is concluded that the ultimate load carrying capacity of the R.C.C. beam strengthened with CFRP sheets increased in the range of 13.01% to 55.32%. Among all the strengthening schemes, the strengthening with CFRP around and inside the opening was found very effective in improving the ultimate load carrying capacity of beam.

  18. NIBLES - an HI census of stellar mass selected SDSS galaxies: I. The Nan\\c{c}ay HI survey

    CERN Document Server

    van Driel, W; Schneider, S; Lehnert, M D; Minchin, R; Blyth, S-L; Chemin, L; Hallet, N; Joseph, T; Kotze, P; Kraan-Korteweg, R C; Olofsson, A O H; Ramatsoku, M


    To investigate galaxy properties as a function of their total stellar mass, we obtained 21cm HI line observations at the 100-m class Nan\\c{c}ay Radio Telescope of 2839 galaxies from the Sloan Digital Sky Survey (SDSS) in the Local Volume (900c{c}ay Interstellar Baryons Legacy Extragalactic Survey (NIBLES) sample. They were selected evenly over their entire range of absolute SDSS z-band magnitudes (-13.5 to -24 mag), which were used as a proxy for their stellar masses. Here, a first, global presentation of the observations and basic results is given, their further analysis will be presented in other papers in this series. The galaxies were selected based on their properties, as listed in SDSS DR5. Comparing this photometry to their total HI masses, we noted that, for a few percent, the SDSS magnitudes appeared severely misunderestimated, as confirmed by our re-measurements for selected objects. Although using the later DR9 results eliminated this problem in most cases, 38...

  19. Preparation and characteristics of C/C composite brake disc by multi-cylindrical chemical vapor deposition processes

    Institute of Scientific and Technical Information of China (English)

    YUAN Yi-dong; ZHANG Fu-kuan; ZHOU Wan-cheng


    The C/C composite brake discs were prepared by tri-cylindrical chemical vapor deposition (CVD) process. The optimum processing parameters were as follows: deposition temperature was 830-930 ℃, the gas-flow rates of N2 and propylene were 4.8-5.2 m3/h and 5.8-6.2 m3/h, respectively, the furnace pressure was 4.5-5.5 kPa and the deposition time was 200 h.The effects of processing parameters on the densified rates, thermal-physical property and mechanical performance of C/C composite brake discs were studied. The results show that density, heat conductivity, bend strength and abrasion ratio of the multi-cylindrica brake discs are 1.02-1.78 g/cm3, 31 W/(m·K), 114 MPa and 7 μm/s, respectively, which are approximately similar to those of the single-cylindrical ones. The gas flow rate has no relation to the number of the cylinder and furnace loading. The utilization ratio of carbon can be improved by multi-cylinder CVD process without changing the characteristics of brake disc.

  20. First observation of the isospin violating decay $J/\\psi\\rightarrow \\Lambda\\bar{\\Sigma}^{0}+c.c.$

    CERN Document Server

    Ablikim, M; Ambrose, D J; An, F F; An, Q; An, Z H; Bai, J Z; Ban, Y; Becker, J; Berger, N; Bertani, M; Bian, J M; Boger, E; Bondarenko, O; Boyko, I; Briere, R A; Bytev, V; Cai, X; Cakir, O; Calcaterra, A; Cao, G F; Cetin, S A; Chang, J F; Chelkov, G; Chen, G; Chen, H S; Chen, J C; Chen, M L; Chen, S J; Chen, Y; Chen, Y B; Cheng, H P; Chu, Y P; Cronin-Hennessy, D; Dai, H L; Dai, J P; Dedovich, D; Deng, Z Y; Denig, A; Denysenko, I; Destefanis, M; Ding, W M; Ding, Y; Dong, L Y; Dong, M Y; Du, S X; Fang, J; Fang, S S; Fava, L; Feldbauer, F; Feng, C Q; Ferroli, R B; Fu, C D; Fu, J L; Gao, Y; Geng, C; Goetzen, K; Gong, W X; Gradl, W; Greco, M; Gu, M H; Gu, Y T; Guan, Y H; Guo, A Q; Guo, L B; Guo, Y P; Han, Y L; Hao, X Q; Harris, F A; He, K L; He, M; He, Z Y; Held, T; Heng, Y K; Hou, Z L; Hu, H M; Hu, J F; Hu, T; Huang, B; Huang, G M; Huang, J S; Huang, X T; Huang, Y P; Hussain, T; Ji, C S; Ji, Q; Ji, X B; Ji, X L; Jia, L K; Jiang, L L; Jiang, X S; Jiao, J B; Jiao, Z; Jin, D P; Jin, S; Jing, F F; Kalantar-Nayestanaki, N; Kavatsyuk, M; Kuehn, W; Lai, W; Lange, J S; Li, C H; Li, Cheng; Li, Cui; Li, D M; Li, F; Li, G; Li, H B; Li, J C; Li, K; Li, Lei; Li, N B; Li, Q J; Li, S L; Li, W D; Li, W G; Li, X L; Li, X N; Li, X Q; Li, X R; Li, Z B; Liang, H; Liang, Y F; Liang, Y T; Liao, G R; Liao, X T; Liu, B J; Liu, C L; Liu, C X; Liu, C Y; Liu, F H; Liu, Fang; Liu, Feng; Liu, H; Liu, H B; Liu, H H; Liu, H M; Liu, H W; Liu, J P; Liu, K Y; Liu, Kai; Liu, Kun; Liu, P L; Liu, S B; Liu, X; Liu, X H; Liu, Y; Liu, Y B; Liu, Z A; Liu, Zhiqiang; Liu, Zhiqing; Loehner, H; Lu, G R; Lu, H J; Lu, J G; Lu, Q W; Lu, X R; Lu, Y P; Luo, C L; Luo, M X; Luo, T; Luo, X L; Lv, M; Ma, C L; Ma, F C; Ma, H L; Ma, Q M; Ma, S; Ma, T; Ma, X Y; Ma, Y; Maas, F E; Maggiora, M; Malik, Q A; Mao, H; Mao, Y J; Mao, Z P; Messchendorp, J G; Min, J; Min, T J; Mitchell, R E; Mo, X H; Morales, C Morales; Motzko, C; Muchnoi, N Yu; Muramatsu, H; Nefedov, Y; Nicholson, C; Nikolaev, I B; Ning, Z; Olsen, S L; Ouyang, Q; Pacetti, S; Park, J W; Pelizaeus, M; Peng, H P; Peters, K; Ping, J L; Ping, R G; Poling, R; Prencipe, E; Qi, M; Qian, S; Qiao, C F; Qin, X S; Qin, Y; Qin, Z H; Qiu, J F; Rashid, K H; Rong, G; Ruan, X D; Sarantsev, A; Schaefer, B D; Schulze, J; Shao, M; Shen, C P; Shen, X Y; Sheng, H Y; Shepherd, M R; Song, X Y; Spataro, S; Spruck, B; Sun, D H; Sun, G X; Sun, J F; Sun, S S; Sun, X D; Sun, Y J; Sun, Y Z; Sun, Z J; Sun, Z T; Tang, C J; Tang, X; Tapan, X F Tang I; Thorndike, E H; Tian, H L; Toth, D; Ullrich, M; Varner, G S; Wang, B; Wang, B Q; Wang, K; Wang, L L; Wang, L S; Wang, M; Wang, P; Wang, P L; Wang, Q; Wang, Q J; Wang, S G; Wang, X L; Wang, Y D; Wang, Y F; Wang, Y Q; Wang, Z; Wang, Z G; Wang, Z Y; Wei, D H; Weidenkaff, P; Wen, Q G; Wen, S P; Werner, M; Wiedner, U; Wu, L H; Wu, N; Wu, S X; Wu, W; Wu, Z; Xia, L G; Xiao, Z J; Xie, Y G; Xiu, Q L; Xu, G F; Xu, G M; Xu, H; Xu, Q J; Xu, X P; Xu, Z R; Xue, F; Xue, Z; Yan, L; Yan, W B; Yan, Y H; Yang, H X; Yang, Y; Yang, Y X; Ye, H; Ye, M; Ye, M H; Yu, B X; Yu, C X; Yu, J S; Yu, S P; Yuan, C Z; Yuan, W L; Yuan, Y; Zafar, A A; Zallo, A; Zeng, Y; Zhang, B X; Zhang, B Y; Zhang, C C; Zhang, D H; Zhang, H H; Zhang, H Y; Zhang, J; Zhang, J Q; Zhang, J W; Zhang, J Y; Zhang, J Z; Zhang, S H; Zhang, T R; Zhang, X J; Zhang, X Y; Zhang, Y; Zhang, Y H; Zhang, Y S; Zhang, Z P; Zhang, Z Y; Zhao, G; Zhao, H S; Zhao, J W; Zhao, K X; Zhao, Lei; Zhao, Ling; Zhao, M G; Zhao, Q; Zhao, S J; Zhao, T C; Zhao, X H; Zhao, Y B; Zhao, Z G; Zhemchugov, A; Zheng, B; Zheng, J P; Zheng, Y H; Zheng, Z P; Zhong, B; Zhong, J; Zhou, L; Zhou, X K; Zhou, X R; Zhu, C; Zhu, K; Zhu, K J; Zhu, S H; Zhu, X L; Zhu, X W; Zhu, Y C; Zhu, Y M; Zhu, Y S; Zhu, Z A; Zhuang, J; Zou, B S; Zou, J H; Zuo, J X


    Using a sample of $(225.2\\pm 2.8)\\times 10^6$ $J/\\psi$ events collected with the BESIII detector, we present results of a study of $J/\\psi\\rightarrow \\gamma\\Lambda\\bar{\\Lambda}$ and report the first observation of the isospin violating decay $J/\\psi\\rightarrow\\Lambda\\bar{\\Sigma}^{0}+c.c.$, in which $\\bar{\\Sigma}^{0}$ decays to $\\gamma \\bar{\\Lambda}$. The measured branching fractions are $\\mathcal{B}(J/\\psi\\rightarrow\\bar{\\Lambda}\\Sigma^{0}$) = $(1.46\\pm0.11\\pm0.12) \\times10^{-5}$ and $\\mathcal{B}(J/\\psi\\rightarrow\\Lambda\\bar{\\Sigma^{0}}$) = $(1.37\\pm0.12\\pm0.11) \\times10^{-5}$. We search for $\\Lambda(1520) \\rightarrow \\gamma \\Lambda$ decay, and find no evident signal, and an upper limit for the product branching fraction $\\mathcal{B}(J/\\psi\\rightarrow\\Lambda\\bar{\\Lambda}(1520)+c.c.)\\times \\mathcal{B}(\\Lambda(1520)\\rightarrow\\gamma\\Lambda)<4.1 \\times10^{-6}$ is set at the 90% confidence level. We also report the observation of $\\eta_{c}\\rightarrow\\Lambda\\bar{\\Lambda}$ in $J/\\psi \\rightarrow \\gamma \\eta_{c}$...

  1. [Lipases in catalytic reactions of organic chemistry]. (United States)

    Bezborodov, A M; Zagustina, N A


    Aspects of enzymatic catalysis in lipase-catalyzed reactions of organic synthesis are discussed in the review. The data on modern methods of protein engineering and enzyme modification allowing a broader range of used substrates are briefly summarized. The application of lipase in the preparation of pharmaceuticals and agrochemicals containing no inactive enantiomers and in the synthesis of secondary alcohol enantiomers and optically active amides is demonstrated. The subject of lipase involvement in the C-C bond formation in the Michael reaction is discussed. Data on the enzymatic synthesis of construction materials--polyesters, siloxanes, etc.--are presented. Examples demonstrating the application of lipase enzymatic catalysis in industry are given.

  2. Chiral 4-substituted 2-oxetanones : catalytic stereoselective synthesis, properties and applications

    NARCIS (Netherlands)

    Staring, Aemilianus Gradus Johannes


    In this thesis the catalytic stereoselective synthesis of chiral 4-substituted 2-oxetanones described. Chiral 4-substituted 2-oxetanones are formed by a C,C-bond forming cycloaddition reaction of ketene and reactive, alfa-halogenated aldehydes and ketones. The cycloaddition reaction is catalyzed by

  3. Dendrimer-encapsulated Pd nanoparticles as catalysts for C-C cross-couplings in flow microreactors

    NARCIS (Netherlands)

    Ricciardi, R.; Huskens, J.; Verboom, W.


    The inner walls of glass microreactors were functionalized with dendrimer-encapsulated Pd nanoparticles. The catalysts were efficient for the Heck–Cassar (copper-free Sonogashira) and Suzuki–Miyaura (SMC) cross-coupling reactions. For the Heck–Cassar reaction between iodobenzene and phenylacetylene,

  4. Mechanical and Chemical Characterization of a TiC/C System Synthesized Using a Focus Plasma Arc.

    Directory of Open Access Journals (Sweden)

    Reza Mahmoodian

    Full Text Available Titanium carbide-graphite (TiC/C composite was successfully synthesized from Ti and C starting elemental powders using self-propagating high-temperature synthesis technique in an ultra-high plasma inert medium in a single stage. The TiC was exposed to a high-temperature inert medium to allow recrystallization. The product was then characterized using field emission scanning electron microscopy (FESEM coupled with energy dispersive X-ray analysis (EDX, X-ray diffraction (XRD, Rietveld refinement, nanoindentation, and micro-hardness to determine the product's properties. The recorded micro-hardness of the product was 3660 HV, which is a 14% enhancement and makes is comparable to TiC materials.

  5. Developing conjugated polymers with high electron affinity by replacing a C-C unit with a B←N unit. (United States)

    Dou, Chuandong; Ding, Zicheng; Zhang, Zijian; Xie, Zhiyuan; Liu, Jun; Wang, Lixiang


    The key parameters of conjugated polymers are lowest unoccupied molecular orbital (LUMO) and highest occupied molecular orbital (HOMO) energy levels. Few approaches can simultaneously lower LUMO and HOMO energy levels of conjugated polymers to a large extent (>0.5 eV). Disclosed herein is a novel strategy to decrease both LUMO and HOMO energy levels of conjugated polymers by about 0.6 eV through replacement of a C-C unit by a B←N unit. The replacement makes the resulting polymer transform from an electron donor into an electron acceptor, and is proven by fluorescence quenching experiments and the photovoltaic response. This work not only provides an effective approach to tune the LUMO/HOMO energy levels of conjugated polymers, but also uses organic boron chemistry as a new toolbox to develop conjugated polymers with high electron affinity for polymer optoelectronic devices.

  6. When ab ≠ c - c': published errors in the reports of single-mediator models. (United States)

    Petrocelli, John V; Clarkson, Joshua J; Whitmire, Melanie B; Moon, Paul E


    Accurate reports of mediation analyses are critical to the assessment of inferences related to causality, since these inferences are consequential for both the evaluation of previous research (e.g., meta-analyses) and the progression of future research. However, upon reexamination, approximately 15% of published articles in psychology contain at least one incorrect statistical conclusion (Bakker & Wicherts, Behavior research methods, 43, 666-678 2011), disparities that beget the question of inaccuracy in mediation reports. To quantify this question of inaccuracy, articles reporting standard use of single-mediator models in three high-impact journals in personality and social psychology during 2011 were examined. More than 24% of the 156 models coded failed an equivalence test (i.e., ab = c - c'), suggesting that one or more regression coefficients in mediation analyses are frequently misreported. The authors cite common sources of errors, provide recommendations for enhanced accuracy in reports of single-mediator models, and discuss implications for alternative methods.

  7. Efeito da resina fenólica nas propriedades de tijolos de Al2O3-SiC-C


    Sá,Geraldo Majela de; Cardoso,Antônio Valadão


    Os tijolos refratários do sistema Al2O3-SiC-C foram introduzidos nos revestimentos para carros-torpedo na década de 80. A formação de trincas paralelas à face quente desses tijolos com posterior lascamento da porção afetada é o principal motivo da redução da vida útil desse revestimento. As modificações microestruturais nesses tijolos, combinadas com esforços de natureza mecânica e térmica, são apontadas como a causa mais freqüente da fratura desses refratários. Os resultados da caracterizaçã...

  8. Preparation of Bioactive Calcium Phosphate Coating on Porous C/C Substrate by a Novel Deposition Technique

    Institute of Scientific and Technical Information of China (English)

    XIONG Xinbo; ZENG Xierong; LI Xiaohua; Xie Shenghui; ZOU Chunli


    A novel heat substrate technique,high frequency inductive heat deposition(IHD),was introduced to coat porous carbon materials,C/C and carbon felt to improve their bioactivity.The morphologies,composition and microstructure of the resulting coatings were examined by scanning electron microscopy(SEM),energy dispersive spectra(EDS),X-ray diffractometer(XRD)and Fourier transform infrared spectroscopy (FTIR).The results show that,the calcium phosphate consisted of non-stoichiometric,CO3-containing and plate-like octacalcium phosphate(Ca8-xH2(PO4)6,OCP)could uniformly cover the entire porous surfaces of carbon materials.Good adhesion of the coating to carbon material substrates was observed.

  9. First principles study of the electronic and magnetic structures and bonding properties of UCoC2 ternary, characteristic of C-C units (United States)

    Matar, Samir F.


    The electronic structure of UCoC2, a di-carbide with the C-C units is examined from ab initio with an assessment of the properties of chemical bonding. The energy-volume equation of state shows large anisotropy effects due to C-C alignment along tetragonal c-axis leading to high linear incompressibility. Relevant features of selective bonding of uranium and cobalt with carbon at two different Wyckoff sites and strong C-C interactions are remarkable. The vibrational frequencies for C⋯C stretching modes indicate closer behavior to aliphatic C-C rather than Cdbnd C double bond. A ferromagnetic ground state is proposed from the calculations.

  10. Van Der Waals heterogeneous layer-layer carbon nanostructures involving π···H-C-C-H···π···H-C-C-H stacking based on graphene and graphane sheets. (United States)

    Yuan, Kun; Zhao, Rui-Sheng; Zheng, Jia-Jia; Zheng, Hong; Nagase, Shigeru; Zhao, Sheng-Dun; Liu, Yan-Zhi; Zhao, Xiang


    Noncovalent interactions involving aromatic rings, such as π···π stacking, CH···π are very essential for supramolecular carbon nanostructures. Graphite is a typical homogenous carbon matter based on π···π stacking of graphene sheets. Even in systems not involving aromatic groups, the stability of diamondoid dimer and layer-layer graphane dimer originates from C - H···H - C noncovalent interaction. In this article, the structures and properties of novel heterogeneous layer-layer carbon-nanostructures involving π···H-C-C-H···π···H-C-C-H stacking based on [n]-graphane and [n]-graphene and their derivatives are theoretically investigated for n = 16-54 using dispersion corrected density functional theory B3LYP-D3 method. Energy decomposition analysis shows that dispersion interaction is the most important for the stabilization of both double- and multi-layer-layer [n]-graphane@graphene. Binding energy between graphane and graphene sheets shows that there is a distinct additive nature of CH···π interaction. For comparison and simplicity, the concept of H-H bond energy equivalent number of carbon atoms (noted as NHEQ), is used to describe the strength of these noncovalent interactions. The NHEQ of the graphene dimers, graphane dimers, and double-layered graphane@graphene are 103, 143, and 110, indicating that the strength of C-H···π interaction is close to that of π···π and much stronger than that of C-H···H-C in large size systems. Additionally, frontier molecular orbital, electron density difference and visualized noncovalent interaction regions are discussed for deeply understanding the nature of the C-H···π stacking interaction in construction of heterogeneous layer-layer graphane@graphene structures. We hope that the present study would be helpful for creations of new functional supramolecular materials based on graphane and graphene carbon nano-structures. © 2017 Wiley Periodicals, Inc.

  11. Capture reactions

    NARCIS (Netherlands)

    Endt, P.M.


    Capture reactions will be considered here from the viewpoint of the nuclear spectroscopist. Especially important to him are the capture of neutrons, protons, and alpha particles, which may proceed through narrow resonances, offering a well defined initial state for the subsequent deexcitation proces

  12. The Prowess of Photogenerated Amine Radical Cations in Cascade Reactions: From Carbocycles to Heterocycles. (United States)

    Morris, Scott A; Wang, Jiang; Zheng, Nan


    with alkynes. In our work on electrophilic addition reactions to alkenes, we reveal that photogenerated amine radical cations are capable of undergoing the electrophilic addition reactions to alkenes to form a variety of indoles and indolines. This chemistry represents a rare oxidative C-N bond-forming reaction using visible light. Conclusions drawn from observational results and proposed mechanisms are outlined in this Account. Additionally, open discussion of our successes and deficiencies in our experiences will give readers helpful insights as to how these species tend to react. The overall utility of photogenerated amine radical cations has yet to reach its full potential. With our current results, we anticipate more new transformations can still be derived from the ring opening processes of cyclopropylanilines and cyclobutylanilines under visible light photocatalysis. Additionally, since utilizing photogenerated amine radical cations in C-N bond-forming reactions has practically been absent in literature, we are confident more new reactions have yet been exploited.

  13. 碳布铺层方式对C/C-SiC薄壁喉衬性能的影响%Effect of Carbon Cloth Spreading Means on Performance of C/C-SiC Thin-Wall Throat

    Institute of Scientific and Technical Information of China (English)

    王玲玲; 嵇阿琳; 纪伶伶; 闫联生; 韩明


    通过CVI+PIP制备了准三维针刺C/C-SiC薄壁喉衬,预制体碳布铺层方式分别采用与喉衬内型面形状相同的仿形铺层以及与喉衬入口端角度相同30°铺层.研究了两种铺层方式对最终构件层间弯曲性能、整体承压性能以及抗烧蚀抗冲刷的影响.结果表明,构件的弯曲强度分别为205和152 MPa;水压爆破压力分别为6.5和4.9 MPa.用与材料表面夹角为30°的氧乙炔气流考查材料的抗烧蚀及冲刷性能,同角度铺层成型材料抗冲刷能力明显较好,200 s其线烧蚀率为仿形铺层成型材料的70%.

  14. Microwave-Assisted Synthesis of 5-Phenyl-2-Hydroxyacetophenone Derivatives by a Green Suzuki Coupling Reaction (United States)

    Soares, Pedro; Fernandes, Carlos; Chavarria, Daniel; Borges, Fernanda


    In recent years, the use of boron-containing reagents in palladium-assisted C-C coupling reactions (the Suzuki reaction) has gained prominence due to the vast array of reagents commercially available. Consequently, the generation of carbon-carbon bonds, namely of functionalized biphenyl systems, is at present considered the backbone of organic…

  15. C-C stretching Raman spectra and stabilities of hydrocarbon molecules in natural gas hydrates: a quantum chemical study. (United States)

    Liu, Yuan; Ojamäe, Lars


    The presence of specific hydrocarbon gas molecules in various types of water cavities in natural gas hydrates (NGHs) are governed by the relative stabilities of these encapsulated guest molecule-water cavity combinations. Using molecular quantum chemical dispersion-corrected hybrid density functional computations, the interaction (ΔE(host--guest)) and cohesive energies (ΔE(coh)), enthalpies, and Gibbs free energies for the complexes of host water cages and hydrocarbon guest molecules are calculated at the ωB97X-D/6-311++G(2d,2p) level of theory. The zero-point energy effect of ΔE(host-guest) and ΔE(coh) is found to be quite substantial. The energetically optimal host-guest combinations for seven hydrocarbon gas molecules (CH4, C2H6, C3H6, C3H8, C4H8, i-C4H10, and n-C4H10) and various water cavities (D, ID, T, P, H, and I) in NGHs are found to be CH4@D, C2H6@T, C3H6@T, C3H8@T, C4H8@T/P/H, i-C4H10@H, and n-C4H10@H, as the largest cohesive energy magnitudes will be obtained with these host-guest combinations. The stabilities of various water cavities enclosing hydrocarbon molecules are evaluated from the computed cohesive Gibbs free energies: CH4 prefers to be trapped in a ID cage; C2H6 prefer T cages; C3H6 and C3H8 prefer T and H cages; C4H8 and i-C4H10 prefer H cages; and n-C4H10 prefer I cages. The vibrational frequencies and Raman intensities of the C-C stretching vibrational modes for these seven hydrocarbon molecules enclosed in each water cavity are computed. A blue shift results after the guest molecule is trapped from gas phase into various water cages due to the host-guest interactions between the water cage and hydrocarbon molecule. The frequency shifts to the red as the radius of water cages increases. The model calculations support the view that C-C stretching vibrations of hydrocarbon molecules in the water cavities can be used as a tool to identify the types of crystal phases and guest molecules in NGHs.

  16. HCO, c-C3H and CF+ : three new molecules in diffuse, translucent and "spiral-arm'' clouds

    CERN Document Server

    Liszt, H; Gerin, M; Lucas, R


    %methods {We used the EMIR receiver and FTS spectrometer at the IRAM 30m to construct absorption spectra toward bright extra-galactic background sources at 195 kHz spectral resolution ($\\approx$ 0.6 \\kms). We used the IRAM Plateau de Bure interferometer to synthesize absorption spectra of \\hthcop\\ and HCO toward the galactic HII region W49.} %results {HCO, \\cc3h\\ and CF\\p\\ were detected toward the blazars \\bll\\ and 3C111 having \\EBV\\ = 0.32 and 1.65 mag. HCO was observed in absorption from ``spiral-arm'' clouds in the galactic plane occulting W49. The complement of detectable molecular species in the 85 - 110 GHz absorption spectrum of diffuse/translucent gas is now fully determined at rms noise level $\\delta_\\tau \\approx 0.002$ at \\EBV\\ = 0.32 mag (\\AV\\ = 1 mag) and $\\delta_\\tau$/\\EBV\\ $\\approx\\ 0.003$ mag$^{-1}$ overall.} %conclusions {As with OH, \\hcop\\ and \\cch, the relative abundance of \\cc3h\\ varies little between diffuse and dense molecular gas, with N(\\cc3h)/N({\\it o-c}-\\c3h2) $\\approx$ 0.1. We find N...

  17. Eco-Friendly Smokeless Al2O3-SiC-C Brick for Hot Metal Ladle

    Institute of Scientific and Technical Information of China (English)



    Hot metal transfer ladles were historically lined with high alumina refractories because of compatibility of high alumina refractories with the highly acidic slag, which is transferred from the iron making plant along with hot metal. With the introduction of higher capacity ladles, technological advancement in the process and increased productivity, calls for a higher campaign life of hot metal ladles, which could not be performed by ordinary high alumina refractories. Resin bonded Al2O3-SiC-C(hereinafter ASC)bricks gradually developed which at present taking place replacing the conventional refractories. Considerable work has been carried out in developing the ASC refractory to reach the present state. However, for higher capacity ladles still there is a lot of scope for improvement The present paper deals with the newly developed ASC bricks, which was used in 165 ton capacity hot metal ladles in one European plant and has given a substantial increase in performance. But, the customer was not fully satisfied since the brick was reported to produce smokes during preheating of the ladle. In the subsequent supply the smoke generation problem was taken care by adjusting the binders and additives and eco-friendly bricks were re-engineered and supplied to the same plant, which also performed splendidly and created all time record in their plant history.

  18. Lead Screening for HIV of C-C Chemokine Receptor Type 5 Receptor Inhibited by Traditional Chinese Medicine

    Directory of Open Access Journals (Sweden)

    Tzu-Chieh Hung


    Full Text Available The acquired immunodeficiency syndrome (AIDS, caused by the human immunodeficiency virus (HIV, has become a serious world-wide problem because of this disease's rapid propagation and incurability. Recent research has pointed out that the C-C chemokine receptor type 5 (CCR5 is an important target for HIV infection. The traditional Chinese medicine (TCM database ( has been screened for molecular compounds that, by simulating molecular docking and molecular dynamics, may protect CCR5 against HIV. Saussureamine C, 5-hydroxy-L-tryptophan, and abrine are selected based on the docking score being higher than Maraviroc and other TCM compounds. The molecular dynamics are helpful in the analysis and detection of protein-ligand interactions. According to the docking poses, hydrophobic interactions, and hydrogen bond variations, this research surmises TRP86, TYR108, GLN194, TYR251, and GLU283 are the main regions of important amino acids in CCR5. In addition to the detection of TCM compound efficacy, we suggest saussureamine C is better than the others for maintaining protein composition during protein-ligand interaction, based on the structural variation.

  19. Influence of load on sliding tribology of C/C composite with 40Cr steel couple coated by Cr

    Institute of Scientific and Technical Information of China (English)

    GE Yi-cheng; YI Mao-zhong; LI Li-ya


    With the 40Cr steel couple coated by Cr, the sliding tribology behavior of two kinds of C/C composites with different matrix was tested using a M2000 wear tester. The results show that with the increasing of load, the friction coefficients of the composite with resin carbon matrix(RC) decrease quickly from 0.156 under 60 N to 0.123 under 150 N, while those of the composite with rough lamination/smooth lamination /resin carbon (RL/SL/RC) change only between 0.122 and 0.101. The wear volume loss of the two composites increases except for under 100 N. The SEM morphology shows that with the increasing of load, the worn surface of the composite with RC becomes more and more integrated while the size of the debris becomes less and less. The Raman spectrum shows that the graphitization on the worn surface of the fibers draws down after 100 N, the graphitization of the boundary between the fiber and the matrix carbon rises up to 150 N, but the graphitization of the matrix carbon draws down all the while. With the increasing of load, the graphitization on the worn surface of all the worn areas becomes closer and closer, which indicates the worn surface of the different component has the similar friction ability. The composites with RL/SL/RC have better tribological characteristic than the composite with RC.

  20. Association of TNF -1031 C/C as a potential protection marker for leprosy development in Amazonas state patients, Brazil. (United States)

    Silva, G A V; Ramasawmy, R; Boechat, A L; Morais, A C; Carvalho, B K S; Sousa, K B A; Souza, V C; Cunha, M G S; Barletta-Naveca, R H; Santos, M P; Naveca, F G


    Polymorphisms present in the TNF promoter region has shown to influence the gene transcription. Leprosy displays different clinical manifestations according to the immune responses of the individual infected with Mycobacterium leprae. In this study, we evaluated the single nucleotide polymorphisms (SNPs) -238 G/A (rs361525), -308 G/A (rs1800629), -857 C/T (rs1799724), -863 A/C (rs1800630) and -1031 T/C (rs1799964) in the promoter region of the TNF to see whether these SNPs influence host-susceptibility to leprosy and the different clinical manifestation. Nucleotide sequencing was performed with DNA samples from 108 leprosy patients and 253 control subjects. An association between -1031 C/C genotype and protection from leprosy was observed when leprosy patients were compared to controls (OR 0.11; 95% CI=0.01-0.82; p=0.012). The -857 C/T genotype may be associated with susceptibility to leprosy (OR=1.81; 95% CI=1.09-3.00; p=0.028). Similar genotype and allele frequencies for the SNPs -308 G/A and -238 G/A were observed between leprosy patients and control subjects. Altogether, TNF polymorphisms in the promoter region may be predictive of leprosy outcome.

  1. Density Functional Study on the Reaction Mechanism for the Reaction of Ni+ with Ethane

    Institute of Scientific and Technical Information of China (English)

    ZHANG,Dong-Ju(张冬菊); LIU,Cheng-Bu(刘成卜); LIU,Yong-Jun(刘永军); HU,Hai-Quan(胡海泉)


    The mechanism of the reaction of Ni+ (2D) with ethane in the gas-phase was studied by using density functional theory. Both the B3LYP and BLYP functionals with standard all-electron basis sets are used to give the detailed information of the potential energy surface (PES) of [Ni, C2, H6 ] +. Tne mechanisms forming the products CH4 and H2 in the reaction of Ni+with ethane are proposed. The reductive eliminations of CH4and H2 are typical addition-elimination reactions. Each of the two reactions consists of two elementary steps: C-C or CH bond activations to form inserted species followed by isomerizations to form product-like intermediate. The rate determining steps for the elimination reatcions of forming CH4 and H2 are the isomerizations of the inserted species rather than C-C or C-H bond activations. The elimination reaction of forming H2 was found to be thermodynamically favored compared to that of CH4.

  2. Hierarchical MoO2/Mo2C/C Hybrid Nanowires as High-Rate and Long-Life Anodes for Lithium-Ion Batteries. (United States)

    Yang, Lichun; Li, Xiang; Ouyang, Yunpeng; Gao, Qingsheng; Ouyang, Liuzhang; Hu, Renzong; Liu, Jun; Zhu, Min


    Hierarchical MoO2/Mo2C/C hybrid nanowires (MoO2/Mo2C/C HNWs) have been fabricated through facile calcination of Mo3O10(C6H5NH3)2·2H2O nanowires which serve as both precursors and self-templates. In the MoO2/Mo2C/C HNWs, nanoparticles dispersed in the nanowires are beneficial for Li(+) transportation due to the decreased diffusion paths. Moreover, hybridization with Mo2C and carbon facilitates the electron transfer and increases the structural stability without sacrifice of capacity. As anode materials for lithium-ion batteries, the MoO2/Mo2C/C HNWs exhibit a reversible capacity of 950 mA h g(-1) after 320 cycles at a current density of 200 mA g(-1). Even when cycled at 2000 mA g(-1), they maintained a reversible capacity of 602 mA h g(-1) after 500 cycles. By incorporation of Mo2C and C with MoO2, the MoO2/Mo2C/C HNWs show high-rate capability and long cycle life and can be a promising candidate for lithium-ion battery anodes.

  3. Reactivity of Tp(Me2) -supported yttrium alkyl complexes toward aromatic N-heterocycles: ring-opening or C-C bond formation directed by C-H activation. (United States)

    Yi, Weiyin; Zhang, Jie; Huang, Shujian; Weng, Linhong; Zhou, Xigeng


    Unusual chemical transformations such as three-component combination and ring-opening of N-heterocycles or formation of a carbon-carbon double bond through multiple C-H activation were observed in the reactions of Tp(Me2) -supported yttrium alkyl complexes with aromatic N-heterocycles. The scorpionate-anchored yttrium dialkyl complex [Tp(Me2) Y(CH2 Ph)2 (THF)] reacted with 1-methylimidazole in 1:2 molar ratio to give a rare hexanuclear 24-membered rare-earth metallomacrocyclic compound [Tp(Me2) Y(μ-N,C-Im)(η(2) -N,C-Im)]6 (1; Im=1-methylimidazolyl) through two kinds of C-H activations at the C2- and C5-positions of the imidazole ring. However, [Tp(Me2) Y(CH2 Ph)2 (THF)] reacted with two equivalents of 1-methylbenzimidazole to afford a C-C coupling/ring-opening/C-C coupling product [Tp(Me2) Y{η(3) -(N,N,N)-N(CH3 )C6 H4 NHCHC(Ph)CN(CH3 )C6 H4 NH}] (2). Further investigations indicated that [Tp(Me2) Y(CH2 Ph)2 (THF)] reacted with benzothiazole in 1:1 or 1:2 molar ratio to produce a C-C coupling/ring-opening product {(Tp(Me2) )Y[μ-η(2) :η(1) -SC6 H4 N(CHCHPh)](THF)}2 (3). Moreover, the mixed Tp(Me2) /Cp yttrium monoalkyl complex [(Tp(Me2) )CpYCH2 Ph(THF)] reacted with two equivalents of 1-methylimidazole in THF at room temperature to afford a trinuclear yttrium complex [Tp(Me2) CpY(μ-N,C-Im)]3 (5), whereas when the above reaction was carried out at 55 °C for two days, two structurally characterized metal complexes [Tp(Me2) Y(Im-Tp(Me2) )] (7; Im-Tp(Me2) =1-methyl-imidazolyl-Tp(Me2) ) and [Cp3 Y(HIm)] (8; HIm=1-methylimidazole) were obtained in 26 and 17 % isolated yields, respectively, accompanied by some unidentified materials. The formation of 7 reveals an uncommon example of construction of a CC bond through multiple C-H activations.

  4. Unusual C-C bond cleavage in the formation of amine-bis(phenoxy) group 4 benzyl complexes: Mechanism of formation and application to stereospecific polymerization

    KAUST Repository

    Gowda, Ravikumar R.


    Group 4 tetrabenzyl compounds MBn4 (M = Zr, Ti), upon protonolysis with an equimolar amount of the tetradentate amine-tris(phenol) ligand N[(2,4-tBu2C6H2(CH 2)OH]3 in toluene from -30 to 25 °C, unexpectedly lead to amine-bis(phenoxy) dibenzyl complexes, BnCH2N[(2,4- tBu2C6H2(CH2)O] 2MBn2 (M = Zr (1), Ti (2)) in 80% (1) and 75% (2) yields. This reaction involves an apparent cleavage of the >NCH2-ArOH bond (loss of the phenol in the ligand) and formation of the >NCH 2-CH2Bn bond (gain of the benzyl group in the ligand). Structural characterization of 1 by X-ray diffraction analysis confirms that the complex formed is a bis(benzyl) complex of Zr coordinated by a newly derived tridentate amine-bis(phenoxy) ligand arranged in a mer configuration in the solid state. The abstractive activation of 1 and 2 with B(C6F 5)3·THF in CD2Cl2 at room temperature generates the corresponding benzyl cations {BnCH2N[(2,4- tBu2C6H2(CH2)O] 2MBn(THF)}+[BnB(C6F5) 3]- (M = Zr (3), Ti, (4)). These cationic complexes, along with their analogues derived from (imino)phenoxy tri- and dibenzyl complexes, [(2,6-iPr2C6H3)N=C(3,5- tBu2C6H2)O]ZrBn3 (5) and [2,4-Br2C6H2(O)(6-CH2(NC 5H9))CH2N=CH(2-adamantyl-4-MeC 6H2O)]ZrBn2 (6), have been found to effectively polymerize the biomass-derived renewable β-methyl-α-methylene- γ-butyrolactone (βMMBL) at room temperature into the highly stereoregular polymer PβMMBL with an isotacticity up to 99% mm. A combined experimental and DFT study has yielded a mechanistic pathway for the observed unusual C-C bond cleavage in the present protonolysis reaction between ZrBn4 and N[(2,4-tBu2C 6H2(CH2)OH]3 for the formation of complex 1, which involves the benzyl radical and the Zr(III) species, resulting from thermal and photochemical decomposition of ZrBn4, followed by a series of reaction sequences consisting of protonolysis, tautomerization, H-transfer, oxidation, elimination, and radical coupling. © 2014 American Chemical Society.

  5. Heavy quark symmetry and weak decays of the b baryons in pentaquarks with a c c xAF component (United States)

    Ali, Ahmed; Ahmed, Ishtiaq; Aslam, M. Jamil; Rehman, Abdur


    The discovery of the baryonic states Pc+(4380 ) and Pc+(4450 ) by the LHCb collaboration in the process p p →b b ¯→Λb0X , followed by the decay Λb0→J /ψ p K- has evoked a lot of theoretical interest. These states have the minimal quark content c c ¯u u d , as suggested by their discovery mode J /ψ p , and the preferred JP assignments are 5/2+ for the Pc+(4450 ) and 3/2- for the Pc+(4380 ). In the compact pentaquark hypothesis, in which they are interpreted as hidden charm diquark-diquark-antiquark baryons, the assigned spin and angular momentum quantum numbers are Pc+(4380 )={c ¯ [c u ]s =1[u d ]s =1;LP=0 ,JP=3/2-} and Pc+(4450 )={c ¯[c u ]s=1[u d ]s=0;LP=1 ,JP=5/2+}. The subscripts denote the spin of the diquarks and LP=0 , 1 are the orbital angular momentum quantum numbers of the pentaquarks. We point out that in the heavy quark limit, the spin of the light diquark in heavy baryons becomes a good quantum number, which has consequences for the decay Λb0→J /ψ p K-. With the quantum numbers assigned above for the two pentaquarks, this would allow only the higher mass pentaquark state Pc+(4450 ) having [u d ]s=0 to be produced in Λb0 decays, whereas the lower mass state Pc+(4380 ) having [u d ]s=1 is disfavored, requiring a different interpretation. Pentaquark spectrum is rich enough to accommodate a JP=3/2- state, which has the correct light diquark spin {c ¯[c u ]s=1[u d ]s=0;LP=0 ,JP=3/2-} to be produced in Λb0 decays. Assuming that the mass difference between the charmed pentaquarks which differ in the orbital angular momentum L by one unit is similar to the corresponding mass difference in the charmed baryons, m [Λc+(2625 );JP=3/2-]-m [Λc+(2286 );JP=1/2+]≃341 MeV , we estimate the mass of the lower pentaquark JP=3 /2- state to be about 4110 MeV and suggest to reanalyze the LHCb data to search for this third state. Extending these considerations to the pentaquark states having a c c ¯ pair and three light quarks (u , d , s ) in their

  6. Cyclic Trinuclear Gold(I) Clusters with N,N and Unusual C,C Mixed-Ligand Bridges. (United States)

    Melgarejo, Doris Y; Chiarella, Gina M; Fackler, John P


    Three crystalline trinuclear gold(I) clusters, [Au3f2y] (1), [Au3fy2] (2), and [Au3y3] (3), where f = N,N'-bis(2,6-dimethylphenyl)methanimidamidate and y = dimethylendiphenylphosphinate, exhibit bridges from the N,N-formamidinate and/or from the ylide anion ligand whose P-methylene groups chelate in an unusual fashion, where the chelate CPC unit is perpendicular to the trigonal plane of the metal atoms. Assemblies 1 and 2 are the first gold(I) trinuclear clusters featuring mixed-ligand bridges from different N,N and C,C donors; 3 is a previously unknown homoleptic ylide anion cyclic trinuclear assembly. Formamidinate bridges in 1 and 2 connect gold(I) atoms at aurophilic distances of 3.084(2) and 3.0543(4) Å, whereas an out-of-plane (perpendicular) P-ylide anion bite produces Au(I)-Au(I) distances of as large as 3.900(2) Å in 3. The crystal space groups for 1 and 2 are triclinic P1̅ and that for 3 is monoclinic P21/c, with Z = 2 for 1 and 2 and Z = 4 for 3. Compounds are synthesized under Schlenk conditions at -20 °C in toluene by reacting the proper ratios of the gold(I) formamidinate [Au2f2] with the phosphorus ylide [Hy] under basic conditions (KOH), followed by extraction with ether. This synthesis also produces a dinuclear cation, [Au2f(Hy)2](+), previously reported by our group. A neutral mixed-ligand dinuclear complex, [Au2fy], was not observed. Under UV light, 1 and 2 display a bright-green luminescence at room temperature and in frozen methyltetrahydrofuran solutions under liquid nitrogen, with microsecond lifetimes. All three complexes 1-3 are characterized by their X-ray crystal structures, (1)H NMR, IR, UV-visible, and luminescence spectroscopies, and elemental analysis.

  7. Effects of Electro-fused Magnesia on Properties of Al2O3 - SiC - C Castable

    Institute of Scientific and Technical Information of China (English)

    NAN Bingqiang; LI Yousheng; LI Nan


    Al2O3- SiC - C castables for iron trough with fused magnesia powder (0, 3% , 6% , 9% and 12% ) were prepared with brown fused corundum particles (5 -3 mm, 3-1 mm, ≤1 mm), white fused corundum powder (≤0. 088 mm), SiC particle (≤1 mm) and powder (≤0. 088 mm ) , fused magnesia powder (≤ 0.088 mm ), reactive α-Al2O3 micropowder, ultrafine SiO2, Si powder and sphere pitch as main starting mate-rials and calcium aluminate cement as binder. The spec-imens were fired at 1 100 ℃ and 1 450 ℃ for 3 h after vibrating moulding, curing, demoulding and drying at 110 ℃ for 24 h. Bulk density, apparent porosity, line-ar change rate, modulus of rupture, resistance to blast furnace slag, oxidation resistance, phase composition and microstructure of the specimens were analyzed. The results show that : ( 1 ) With fused magnesia addition increasing, apparent porosity increases, while bulk den-sity, modulus of rupture and oxidation resistance de-cline, slag resistance varies slightly; (2) The main crystal phases in the specimens fired at 1 450 ℃ for 3 h are 3C-SiC, 6H - SiC, corundum, periclase, reac-tion-synthesized spinel and mullite; the quantity of the formed spinel and mullite increases with the increase of fased magnesite addition; (3) Along the corroded side, spinel layer with about 80 μm thickness forms at the co-rundum particles boundary.

  8. Production of $Y(4260)$ as a hadronic molecule state of $\\bar{D}D_1 +c.c.$ in $e^+e^-$ annihilations

    CERN Document Server

    Qin, Wen; Zhao, Qiang


    We investigate the $Y(4260)$ production in $e^+e^-$ annihilations and probe its structure as the $\\bar{D}D_1+c.c.$ hadronic molecule state. By introducing a compact $c\\bar{c}$ component into the wavefunction in addition to the long-ranged molecular one, we show that the compositeness relation can still provide a reasonable constraint on the wavefunction renormalization parameter. This study confirms the earlier work that the $Y(4260)$ contains predominantly a $\\bar{D}D_1+c.c.$ molecular component, and its decays into the $\\bar{D}D^*\\pi+c.c.$ channel should have a nontrivial lineshape. It provides a natural explanation for the production of $Y(4260)$ in $e^+e^-$ annihilations in the same framework. It also allows us to predict the $Y(4260)$ leptonic decay width of which the upper limit is about 500 eV.

  9. Acid-base bifunctional catalytic surfaces for nucleophilic addition reactions. (United States)

    Motokura, Ken; Tada, Mizuki; Iwasawa, Yasuhiro


    This article illustrates the modification of oxide surfaces with organic amine functional groups to create acid-base bifunctional catalysts, summarizing our previous reports and also presenting new data. Immobilization of organic amines as bases on inorganic solid-acid surfaces afforded highly active acid-base bifunctional catalysts, which enabled various organic transformations including C--C coupling reactions, though these reactions did not proceed with either the homogeneous amine precursors or the acidic supports alone. Spectroscopic characterization, such as by solid-state MAS NMR and FTIR, revealed not only the interactions between acidic and basic sites but also bifunctional catalytic reaction mechanisms.

  10. Variability of the preC/C region of hepatitis B virus genotype A from a South African cohort predominantly infected with HIV. (United States)

    Mayaphi, Simnikiwe H; Martin, Desmond J; Mphahlele, M Jeffrey; Blackard, Jason T; Bowyer, Sheila M


    Hepatitis B virus (HBV) is a serious global health problem, and HBV genotype is an important determinant of disease progression and treatment outcome. The aim of this study was to assess variations of the precore/core (preC/C) region in HBV genotype A. Sequencing of the preC/C and surface (S) genes of HBV was performed on plasma samples from 20 HBV/HIV co-infected and 5 HBV mono-infected individuals. All preC/C study sequences clustered with subgenotype A1, except for two which clustered with subgenotype D4 reference strains. The nucleotide and amino acid variability was far higher in the preC/C region than in the S region. Mutations associated with reduction or failure of HBV e-antigen (HBeAg) production were observed, with a preC start codon mutation being common (24%). Other mutations (e.g., P5H/L and I97L) associated with severe liver disease were also noticed, some of which were located in the major histocompatibility restricted sites. PreC/C intergenotype nucleotide divergence was >7%, while subgenotypes differed by 2.5-7%. Several study sequences were highly divergent from other African subgenotype A1 strains. This study showed that HBeAg-negative chronic hepatitis B is underestimated in subgenotype A1, and also highlighted the variant South African A1 strains. The major advantage of preC/C sequencing is that it informs patient management as HBeAg-negative chronic hepatitis B responds poorly to conventional interferon-α therapy, and some guidelines treat HBeAg-negative chronic hepatitis B differently from HBeAg-positive chronic hepatitis B. These data suggest that subgenotype A1 may be more involved in severe HBV-related diseases.

  11. Transition Path Sampling Study of the Reaction Catalyzed by Purine Nucleoside Phosphorylase (United States)

    Saen-oon, Suwipa; Schramm, Vern L.; Schwartz, Steven D.


    The Transition Path Sampling (TPS) method is a powerful technique for studying rare events in complex systems, that allows description of reactive events in atomic detail without prior knowledge of reaction coordinates and transition states. We have applied TPS in combination with a hybrid Quantum Mechanical/Molecular Mechanical (QM/MM) method to study the enzyme human purine nucleoside phosphorylase (hPNP). This enzyme catalyzes the reversible phosphorolysis of 6-oxypurine (deoxy)nucleosides to generate the corresponding purine base and (deoxy)ribose 1-phosphate. Hundreds of reactive trajectories were generated. Analysis of this transition path ensembles provides insight into the detailed mechanistic dynamics of reaction in the enzyme. Our studies have indicated a reaction mechanism involving the cleavage of the N-ribosidic bond to form transition states with substantial ribooxacarbenium ion character, that is then followed by conformational changes in the enzyme and the ribosyl group leading to migration of the anomeric carbon of the ribosyl group toward phosphate to form the product ribose 1-phosphate. This latter process is crucial in PNP, because several strong H-bonds form between active site residues in order to capture and align the phosphate nucleophile. Calculations of the commitment probability along reactive paths demonstrated the presence of a broad energy barrier at the transition state. Analysis of these transition state structures showed that bond-breaking and bond-forming distances are not a good choice for the reaction coordinate, but that the pseudorotational phase of the ribose ring is also a significant variable. PMID:20664707

  12. First observation of J/\\psi and \\psi(2S) decaying to n K^0_S\\bar\\Lambda +c.c

    CERN Document Server

    Bai, J Z; Cai, X; Chen, H F; Chen, H S; Chen, H X; Chen, J C; Chen, Jin; Chen, Y B; Chu, Y P; Dai, Y S; Diao, L Y; Deng, Z Y; Dong, Q F; Du, S X; Fang, J; Fang, S S; Fu, C D; Gao, C S; Gao, Y N; Gotzen, K; Gu, S D; Gu, Y T; Guo, Y N; Guo, Z J; Harris, F A; He, K L; He, M; Heng, Y K; Hou, J; Hu, H M; Hu, J H; Hu, T; Huang, G S; Huang, X T; Ji, X B; Jiang, X S; Jiang, X Y; Jiao, J B; Jin, D P; Jin, S; Lai, Y F; Li, G; Li, H B; Li, J; Li, R Y; Li, S M; Li, W D; Li, W G; Li, X L; Li, X N; Li, X Q; Liang, Y F; Liao, H B; Liu, B J; Liu, C X; Liu, F; Liu, Fang; Liu, H H; Liu, H M; Liu, J; Liu, J B; Liu, J P; Liu, Jian; Liu, Q; Liu, R G; Liu, Z A; Lou, Y C; Lu, F; Lu, G R; Lu, J G; Luo, C L; Ma, F C; Ma, H L; Ma, L L; Ma, Q M; Mao, Z P; Mo, X H; Nie, J; Olsen, S L; Peters, K J; Ping, R G; Qi, N D; Qin, H; Qiu, J F; Ren, Z Y; Rong, G; Ruan, X D; Shan, L Y; Shang, L; Shen, C P; Shen, D L; Shen, X Y; Sheng, H Y; Sun, H S; Sun, S S; Sun, Y Z; Sun, Z J; Tang, X; Tong, G L; Varner, G S; Wang, D Y; Wang, L; Wang, L L; Wang, L S; Wang, M; Wang, P; Wang, P L; Wang, W F; Wang, Y F; Wang, Z; Wang, Z Y; Wang, Zheng; Wei, C L; Wei, D H; Weng, Y; Wu, N; Xia, X M; Xie, X X; Xu, G F; Xu, X P; Xu, Y; Yan, M L; Yang, H X; Yang, Y X; Ye, M H; Ye, Y X; Yu, G W; Yuan, C Z; Yuan, Y; Zang, S L; Zeng, Y; Zhang, B X; Zhang, B Y; Zhang, C C; Zhang, D H; Zhang, H Q; Zhang, H Y; Zhang, J W; Zhang, J Y; Zhang, S H; Zhang, X Y; Zhang, Yiyun; Zhang, Z X; Zhang, Z P; Zhao, D X; Zhao, J W; Zhao, M G; Zhao, P P; Zhao, W R; Zhao, Z G; Zheng, H Q; Zheng, J P; Zheng, Z P; Zhou, L; Zhu, K J; Zhu, Q M; Zhu, Y C; Zhu, Y S; Zhu, Z A; Zhuang, B A; Zhuang, X A; Zou, B S


    The decays of $\\jpsi$ and $\\psip$ to ${n}{K^0_S}\\bar{\\Lambda}+c.c.$ are observed and measured for the first time, and the perturbative QCD ``12%'' rule is tested, based on $5.8 \\times 10^7$ $\\jpsi$ and $1.4 \\times 10^7$ $\\psip$ events collected with BESII detector at the Beijing Electron-Positron Collider. No obvious enhancement near $n\\bar{\\Lambda}$ threshold in $\\jpsi \\to {n}{K^0_S}\\bar{\\Lambda}+c.c.$ is observed, and the upper limit on the branching ratio of $\\jpsi \\to {K^0_S} X, X \\to n \\bar \\Lambda$ is determined.

  13. Efficient C-F and C-C activation by a novel N-heterocyclic carbene-nickel(0) complex. (United States)

    Schaub, Thomas; Radius, Udo


    The NHC-stabilized complex [Ni2(iPr2Im)4(cod)] (1) was isolated in good yield from the reaction of [Ni(cod)2] with 1,3-diisopropylimidazole-2-ylidene (iPr2Im). Compound 1 is a source of the [Ni(iPr2Im)2] complex fragment in stoichiometric and catalytic transformations. The reactions of 1 with ethylene and CO under atmospheric pressure or with equimolar amounts of diphenylacetylene lead to the compounds [Ni(iPr2Im)2(eta2-C2H4)] (2), [Ni(iPr2Im)2(eta2-C2Ph2)] (3), and [Ni(iPr2Im)2(CO)2] (4) in good yields. In all cases the [Ni(iPr2Im)2] complex fragment is readily transferred without decomposition or fragmentation. In the infrared spectrum of carbonyl complex 4, the CO stretching frequencies are observed at 1847 and 1921 cm(-1), and are significantly shifted to lower wavenumbers compared with other nickel(0) carbonyl complexes of the type [NiL2(CO)2]. Complex 1 activates the C--F bond of hexafluorobenzene very efficiently to give [Ni(iPr2Im)2(F)(C6F5)] (5). Furthermore, [Ni2(iPr2Im)4(cod)] (1) is also an excellent catalyst for the catalytic insertion of diphenylacetylene into the 2,2' bond of biphenylene. The reaction of 1 with equimolar amounts of biphenylene at low temperature leads to [Ni(iPr2Im)2(2,2'-biphenyl)] (6), which is formed by insertion into the strained 2,2' bond. The reaction of diphenylacetylene and biphenylene at 80 degrees C in the presence of 2 mol % of 1 as catalyst yields diphenylphenanthrene quantitatively and is complete within 30 minutes.

  14. Organic chemistry on surfaces: Direct cyclopropanation by dihalocarbene addition to vinyl terminated self-assembled monolayers (SAMs). (United States)

    Adamkiewicz, Malgorzata; O'Hagan, David; Hähner, Georg


    C11-Vinyl-terminated self-assembled monolayers (SAMs) on silica surfaces are successfully modified in C-C bond forming reactions with dihalocarbenes to generate SAMs, terminated with dihalo- (fluoro, chloro, bromo) cyclopropane motifs with about 30% surface coverage.

  15. Mechanical performance of Hi-Nicalon/CVI-SiC composites with multilayer SiC/C interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Halverson, H.G.; Carter, R.H.; Curtin, W.A. [Virginia Polytechnic Inst. and State Univ., Blacksburg, VA (United States). Dept. of Engineering Science and Mechanics


    The mechanical properties and interfacial characteristics of new SiC/SiC ceramic composites, composed of Hi-Nicalon fibers in a CVI-SiC matrix and having a variety of multilayer SiC/C coatings between the fibers and the matrix, are studied in detail to elucidate the roles of the coatings and fibers. Axial tension tests and unload/reload hysteresis loop measurements are performed to determine mechanical performance. All materials exhibit the strong and tough behavior characteristic of good ceramic composites, with all multilayer variants performing quite similarly. SEM microscopy demonstrates that matrix cracks penetrate through the multilayers and debond at the fiber/inner-coating interface. Analysis of the hysteretic behavior leads to values for interfacial sliding resistance {tau} {approx} 11 ksi and interfacial toughness {Gamma}{sub i} {approx} 2 J/m{sup 2} that are nearly independent of multilayer structure, and are similar to values obtained for standard pyrolitic carbon interfaces. These results all indicate debonding at the fiber surface for all coating structures, which provides a common roughness, {tau}, and {Gamma}{sub i}. Analysis of fiber fracture mirrors provides an estimate of the in-situ strength of the fibers and demonstrates the high strength retention of the Hi-Nicalon fibers. The in-situ fiber strengths are combined with the measured pullout lengths to obtain an independent determination of {tau} = 8.5 ksi that agrees well with the value found from the hysteretic behavior. Predictions of composite strength using the derived fiber strengths agree well with the measured value although the predicted failure strain is too large. This study demonstrates that Hi-Nicalon fiber/CVI-SiC composites perform well for a wide range of multilayer interface structures and that the interfaces present relatively high values of {tau} and {Gamma}{sub i}, both of which are beneficial to strength and toughness. The small carbon layer thicknesses in these multilayer

  16. Chemokine signaling involving chemokine (C-C motif) ligand 2 plays a role in descending pain facilitation

    Institute of Scientific and Technical Information of China (English)

    Wei Guo; Hu Wang; Shiping Zou; Ronald Dubner; Ke Ren


    Objective Despite accumulating evidence on a role of immune cells and their associated chemicals in mechanisms of pain,few studies have addressed the potential role of chemokines in the descending facilitation of persistent pain.The present study was undertaken to test the hypothesis that the chemokine (C-C motif) ligand 2 (CCL2) (commonly known as monocyte chemoattractant protein-1) signaling in the rostral ventromedial medulla (RVM),a pivotal structure in brainstem pain modulatory circuitry,is involved in descending pain facilitation in rats.Methods An L5 spinal nerve ligation (SNL) was produced in rats under pentobarbital anesthesia.Western blot and immunohistochemistry were used to detect the expression levels of CCL2 and CCL2 receptor (CCR2),and examine their distributions compared with the neuronal marker NeuN as well as glial markers glial fibrillary acidic protein (GFAP,astroglial) and CD11b (microglial),respectively.Results SNL induced an increase in CCL2 expression in the RVM,and this returned to the control level at 4 weeks after injury.The induced CCL2 colocalized with NeuN,but not with GFAP and CD11b.CCR2 was also upregulated by SNL in the RVM,and this increase lasted for at least 4 weeks.CCR2 was colocalized with CD1 1b but not GFAP.Few RVM neurons also exhibited CCR2 staining.Neutralizing CCL2 with an anti-CCL2 antibody (0.2-20 ng) or injecting RS-102895 (0.1-10 pmol),a CCR2b chemokine receptor antagonist,into the RVM on day 1 after SNL,significantly attenuated the established thermal and mechanical hypersensitivity.In addition,injection of recombinant rat CCL2 (0.03-3pmol) into the RVM induced dose-dependent hyperalgesia,which was prevented by pretreatment with RS-102895 (10pmol).Interleukin-1β (IL-1β),a potent inducer of neuronal CCL2,was also selectively upregulated in RVM reactive astrocytes.Injection of IL-1β (120 fmol) into the RVM induced behavioral hyperalgesia,which was blocked by RS-102895(10 pmol).However,an IL-1 receptor antagonist (3

  17. 碳纤维增强碳与碳化硅双基体陶瓷基复合材料作为口腔种植体材料的细胞毒性%Cytotoxicity of Carbon Fiber-reinforced C-SiC Binary Matrix Composite (C/C-SiC) for Dental Implant Materials

    Institute of Scientific and Technical Information of China (English)

    方铁钧; 周群; 狄丽莎; 谭兆军; 邓景屹


    目的 通过体外细胞培养法评价碳纤维增强碳与碳化硅双基体陶瓷基复合材料(C/C-SiC)对细胞生长和凋亡的影响.方法 用实验材料不同浓度浸提液培养小鼠成纤维细胞L929,采用MTT法检测细胞的相对增殖度;采用急性溶血试验检测材料对血细胞的溶血作用,计算溶血率;采用流式细胞仪、Annexin V-FITC/PI双染法检测阴性对照组、100%C/C-SiC组、纯钛组、阳性对照组的细胞散点图,计算正常细胞、早期凋亡、晚期凋亡和坏死细胞的比例.结果 C/C-SiC复合材料的细胞毒性为1级,溶血率为0.156%,无明显溶血反应,与阴性对照组和纯钛组的差异无统计学意义(P>0.05).C/C-SiC组4个象限细胞比例与纯钛组和阴性对照组比较差异无统计学意义(P>0.05),阳性对照组的早期凋亡、正常细胞比例与其他任一组比较差异均有统计学意义(P<0.05).结论 C/C-SiC复合材料有生物安全性基础,无细胞毒性,无溶血反应.%Objective To evaluate the effect of C/C-SiC composite on the growth and apoptosis of mouse fibroblast cells. Methods Mouse fibroblasts (L929) were cultured in a series of elution of specimen, MTT assay was performed to investigate the relative growth rates;Hemolytic reaction of specimen to blood cells was detected by acute hemolysis test; Cell scatter diagrams of elutes of negative control group,100%C/C-SiC group,ti tanium group,positive control group was detected by Annexin V-FITC/PI double staining,the viable,early apoptotic,late apoptotic and necrosis cells were calculated. Results The cytotoxicity of C/C-SiC composite was grade 1,acute hemolysis rate was 0.156%. There were no significant differences between the negative control group and C/C-SiC group or between the titanium group and C/CSiC group (P > 0.05 );The FACS images showed that the proportions of cells in four quadrants of titanium group,negative control group were not statistically different from C/C

  18. Toward an Automatic Determination of Enzymatic Reaction Mechanisms and Their Activation Free Energies. (United States)

    Zinovjev, Kirill; Ruiz-Pernía, J Javier; Tuñón, Iñaki


    We present a combination of the string method and a path collective variable for the exploration of the free energy surface associated to a chemical reaction in condensed environments. The on-the-fly string method is employed to find the minimum free energy paths on a multidimensional free energy surface defined in terms of interatomic distances, which is a convenient selection to study bond forming/breaking processes. Once the paths have been determined, a reaction coordinate is defined as a measure of the advance of the system along these paths. This reaction coordinate can be then used to trace the reaction Potential of Mean Force from which the activation free energy can be obtained. This combination of methodologies has been here applied to the study, by means of Quantum Mechanics/Molecular Mechanics simulations, of the reaction catalyzed by guanidinoacetate methyltransferase. This enzyme catalyzes the methylation of guanidinoacetate by S-adenosyl-l-methionine, a reaction that involves a methyl transfer and a proton transfer and for which different reaction mechanisms have been proposed.

  19. Applying Improved Electrical Breakdown Model to Study Insulating Property of c-C4F8/N2 Gas Mixture%Applying Improved Electrical Breakdown Model to Study Insulating Property of c-C4F8/N2Gas Mixture

    Institute of Scientific and Technical Information of China (English)

    LI Xue-wen; XIAO Deng-ming


    Perfluorocyclobutane(c-C4F8) has been recently considered as a potential alternative to SF6,because of its high electro-negativity and extremely low environmental effect.However,due to its high boiling point,c-C4F8 should mixed with buffer gases such as N2 or CO2 in order to avoid the liquefaction at low temperature.This paper investigates insulating properties of c-C4F8/N2 gas mixtures from two aspects including electrical strength,and Global Warming Potential(GWP).Moreover,improved electrical breakdown model of gas mixtures is founded.Breakdown temperature and breakdown electrical field in gas mixtures can be obtained from rigorous Townsend criterion expression according to gas mixtures ratio and cross section data of gas mixtures in this model.Under the condition of different gas pressure (0.1~0.4 Mpa),gas mixtures ratio(0~30%),and electrode gap(2~10 mm),breakdown voltages of gas mixtures are calculated by using of this model.Insulation strength of SF6/N2 mixed gas is compared with c-C4F8/N2 mixed gas in the same conditions.Research results show that theoretical computation corresponds with experiment.If the content of c-C4F8 or SF6 in mixtures is less than 30%,insulation strength between c-C4F8/N2 and SF6/N2 is very close.Considering two indexes (breakdown voltage,GWP),it is suitable for c-C4F8 content being 15%~20% in c-C4F8/N2 gas mixtures.

  20. Computational Study of Low-Temperature Catalytic C-C Bond Activation of Alkanes for Portable Power (United States)


    the RhCl3 system. Our initial computations regarding this system showed that • RhII chloride salts are stable in a mixture of RhI and RhIII, so that...inhibiting the reaction. We found that Fluorinated phosphines are sufficiently π-accepting to satisfy this role. In our next step, we wanted to determine...flames” Proc. Comb. Inst. 2005, 30, 439–446 4. A. Onopchenko, J.G.D. Schulz “Oxidation of butane with cobalt salts and oxygen via electron

  1. FeCl2-promoted cleavage of the unactivated C-C bond of alkylarenes and polystyrene: direct synthesis of arylamines. (United States)

    Qin, Chong; Shen, Tao; Tang, Conghui; Jiao, Ning


    Ironing it out: an efficient and convenient nitrogenation strategy involving C-C bond cleavage for the straightforward synthesis of versatile arylamines is presented. Various alkyl azides and alkylarenes, including the common industrial by-product cumene, react using this protocol. Moreover, this method provides a potential strategy for the degradation of polystyrene.

  2. SiC/C composites prepared from wood-based carbons by pulse current sintering with SiO2 : Electrical and thermal properties

    NARCIS (Netherlands)

    Fujisawa, M; Hata, T; Bronsveld, P; Castro, [No Value; Tanaka, F; Kikuchi, H; Furuno, T; Imamura, Y


    A powder mix of wood charcoal and SiO2 was sintered into a SiC/C composite. The heat treatment temperatures were 1400-1800 degreesC, the SiO2 concentration 0, 10, 30 and 50 wt.% with respect to the dry weight of wood charcoal. The microstructure, electrical resistance and thermal conductivity were s

  3. The electric Kool-Aid NBOMe test: LC-TOF/MS confirmed 2C-C-NBOMe (25C) intoxication at Burning Man. (United States)

    Armenian, Patil; Gerona, Roy R


    Designer drugs are constantly evolving, with the NBOMe derivatives of the 2C class of phenethylamines recently emerging in the US market. Cases of 2C-I-NBOMe toxicity have recently been reported in the literature. No reports to date describe the clinical effects 2C-C-NBOMe toxicity.

  4. Effect of temperature on the low-energy (≲1eV) electron attachment to perfluorocyclobutane ( c-C 4F 8) (United States)

    Christodoulides, A. A.; Christophorou, L. G.; Mccorkle, D. L.


    A large decrease in the total electron attachment rate constant Kfor cC 4F 8 with increasing temperature T (300 to 560 K) has been observed for mean electron energies ≲ 0.8 eV, where the electron attachment is non-dissociative. Possible origins for the observed large negative effect of temperature on Ka() are discussed.

  5. Intramolecular hydroalkoxylation of non-activated C=C bonds catalysed by zeolites: an experimental and theoretical study. (United States)

    Pérez-Mayoral, Elena; Matos, Ines; Nachtigall, Petr; Položij, Miroslav; Fonseca, Isabel; Vitvarová-Procházková, Dana; Čejka, Jiří


    The high activity and selectivity of zeolites in the cyclisation of unsaturated alcohols is reported for the first time; the details of a reaction mechanism based on quantum chemical calculations are also provided. The high efficiency of zeolites MFI, BEA and FAU in the cyclisation of unsaturated alcohols (cis-decen-1-ol, 6-methylhept-5-en-2-ol and 2-allylphenol) to afford oxygen-containing heterocyclic rings is demonstrated. The best catalytic performance is found for zeolites with the optimum concentration of Brønsted acid sites (ca. 0.2 mmol g(-1)) and the minimum number of Lewis acid sites. It is proposed that the efficiency of the catalysts is reduced by the existence of the so-called dual site, at which a molecule of unsaturated alcohol can simultaneously interact with two acid sites (an OH group with one and the double bond with the other Brønsted site), which increases the interaction strength. The formation of such adsorption complexes leads to a decrease in the catalyst activity because of (i) an increase in the reaction barrier, (ii) an unfavourable conformation and (iii) diffusion limitations. A new procedure for the preparation of tetrahydrofurans and pyrans over zeolite catalysts provides important oxygen-containing heterocycles with numerous applications.

  6. Alkynyl functionalized Al/P-based frustrated Lewis pairs - aluminium alkynide elimination and evidence for the formation of 3H-phosphaallenes [R-P=C=C(H)-(t)Bu]. (United States)

    Klöcker, Hans; Roters, Steffi; Hepp, Alexander; Uhl, Werner


    Hydroalumination of dialkynylphosphines, aryl-P(C≡C-(t)Bu)2 (aryl = 2,4,6-Me3C6H2 (1), Ph (2)), with the bulky dialkylaluminium hydride H-Al[CH(SiMe3)2]2 afforded mixed alkenyl-alkynyl phosphines (3 and 4) with aluminium atoms in geminal positions to phosphorus. These compounds contain coordinatively unsaturated aluminium and phosphorus atoms and may be applicable as alkynyl functionalised frustrated Lewis pairs. Their unique constitution with dialkylaluminium and alkynyl groups in close proximity favours unusual secondary reactions with the elimination of an aluminium alkynide and formation of reactive 3H-phosphaallenes, aryl-P=C=C(H)-(t)Bu (5 and 6), which depending on the steric shielding by the aryl groups, oligomerize at room temperature over days or weeks. The mesityl derivative 5 is formed in a very selective reaction, but the relatively unstable phenyl compound 6 was only detected in a mixture of several components. One of these (7) was isolated as orange-red crystals and identified as a heterocyclic zwitterionic compound with a central AlC2P2 ring. One of its phosphorus atoms is bonded to a terminal alkynyl group.

  7. A Novel Strategy for Preparation of Si-HA Coatings on C/C Composites by Chemical Liquid Vaporization Deposition/Hydrothermal Treatments. (United States)

    Xin-Bo, Xiong; Xin-Ye, Ni; Ya-Yun, Li; Cen-Cen, Chu; Ji-Zhao, Zou; Xie-Rong, Zeng


    A novel strategy for the preparation of Si-doped hydroxyapatite (Si-HA) coatings on H2O2-treated carbon/carbon composites (C/C) was developed. HA coating was prepared on C/C through chemical liquid vaporization deposition (CLVD)/hydrothermal treatment. HA coating was immersed in an H2SiO3 solution at an autoclave at 413 K for transformation into Si-HA coating. The effects of H2SiO3 mass contents on the phase, morphology, and composition of the Si-HA coatings were studied through SEM, EDS,XRD, and FTIR. Their bonding performance to C/C was measured through a scratch test. Under the optimal content condition, the in vitro skull osteoblast response behaviors of the Si-HA coating were evaluated. Results showed that SiO3(2-) could enter into the HA lattice and occupy the PO4(3-) sites. Doped SiO3(2-) significantly improved the bonding performance of the HA coating to C/C in comparison with the untreated HA. The adhesive strength of the coatings initially increased and then decreased with increasing H2SiO3 content. Meanwhile, the cohesive strength of the Si-HA coatings was almost nearly identical. The Si-HA coating achieved at a content of 90% H2SiO3 exhibited the best bonding performance, and its osteoblast compatibility in vitro was superior to that of the untreated HA coating on C/C through CLVD/hydrothermal treatment.

  8. A Novel Strategy for Preparation of Si-HA Coatings on C/C Composites by Chemical Liquid Vaporization Deposition/Hydrothermal Treatments (United States)

    Xin-Bo, Xiong; Xin-Ye, Ni; Ya-Yun, Li; Cen-Cen, Chu; Ji-Zhao, Zou; Xie-Rong, Zeng


    A novel strategy for the preparation of Si-doped hydroxyapatite (Si-HA) coatings on H2O2-treated carbon/carbon composites (C/C) was developed. HA coating was prepared on C/C through chemical liquid vaporization deposition (CLVD)/hydrothermal treatment. HA coating was immersed in an H2SiO3 solution at an autoclave at 413 K for transformation into Si-HA coating. The effects of H2SiO3 mass contents on the phase, morphology, and composition of the Si-HA coatings were studied through SEM, EDS,XRD, and FTIR. Their bonding performance to C/C was measured through a scratch test. Under the optimal content condition, the in vitro skull osteoblast response behaviors of the Si-HA coating were evaluated. Results showed that SiO32‑ could enter into the HA lattice and occupy the PO43‑ sites. Doped SiO32‑ significantly improved the bonding performance of the HA coating to C/C in comparison with the untreated HA. The adhesive strength of the coatings initially increased and then decreased with increasing H2SiO3 content. Meanwhile, the cohesive strength of the Si-HA coatings was almost nearly identical. The Si-HA coating achieved at a content of 90% H2SiO3 exhibited the best bonding performance, and its osteoblast compatibility in vitro was superior to that of the untreated HA coating on C/C through CLVD/hydrothermal treatment.

  9. Preparation of High Thermal Conductivity C/C Composite%高导热碳/碳复合材料的制备

    Institute of Scientific and Technical Information of China (English)

    冯志海; 樊桢; 孔清; 余立琼; 徐林


    以中间相沥青和中间相沥青基碳纤维为原料,采用碳布热压法、液相浸渍法制备了二维和三维高导热碳/碳复合材料,且所制得复合材料的热导率分别高达443和340 W/(m·K)。依据碳/碳复合材料的热导率模型,分析了不同结构特征参数对材料热导率的影响。结果表明,基体碳热导率、孔隙率以及界面相厚度均会在一定程度上影响材料的导热性能。%2D high thermal conductivity C/C composite and 3D high thermal conductiv-ity C/C composite were produced through hot pressing and liquid impregnating method, with mesophase pitch-based carbon fiber and mesophase pitch as raw materials. Ther-mal conductivity as high as 443 W/(m·K) and 340 W/(m·K) was achieved for 2D high thermal conductivity C/C composite and 3D high thermal conductivity C/C composite, respectively. The effects of structure parameters on the thermal conductivity were ana-lyzed according to the analytical thermal model of C/C composites. The results show that thermal conductivity of carbon matrix, porosity and interface have different effects on the thermal conductivity of composites.

  10. A biomolecule-compatible visible-light-induced azide reduction from a DNA-encoded reaction-discovery system. (United States)

    Chen, Yiyun; Kamlet, Adam S; Steinman, Jonathan B; Liu, David R


    Using a system that accelerates the serendipitous discovery of new reactions by evaluating hundreds of DNA-encoded substrate combinations in a single experiment, we explored a broad range of reaction conditions for new bond-forming reactions. We discovered reactivity that led to a biomolecule-compatible, Ru(II)-catalysed azide-reduction reaction induced by visible light. In contrast to current azide-reduction methods, this reaction is highly chemoselective and is compatible with alcohols, phenols, acids, alkenes, alkynes, aldehydes, alkyl halides, alkyl mesylates and disulfides. The remarkable functional group compatibility and mild conditions of the reaction enabled the azide reduction of nucleic acid and oligosaccharide substrates, with no detectable occurrence of side reactions. The reaction was also performed in the presence of a protein enzyme without the loss of enzymatic activity, in contrast to two commonly used azide-reduction methods. The visible-light dependence of this reaction provides a means of photouncaging functional groups, such as amines and carboxylates, on biological macromolecules without using ultraviolet irradiation.

  11. Temperature Dependence of a Period of the Modulated Structurein Atom-Vacancy Solid Solution Based on F.C.C. Nickel

    Directory of Open Access Journals (Sweden)

    V.A. Tatarenko


    Full Text Available The effective vacancy–vacancy interaction is considered. Based on the continuum approximation for the Fourier components of strain-induced vacancy–vacancy-interaction energies, approximating expressions for their expansion coefficients are obtained, depending on the elasticity moduli, longitudinal and transverse phonon frequencies, and vacancy-concentration-dependent lattice parameter. A non-analytical behaviour of the k-dependent Fourier components of the strain-induced vacancy–vacancy-interaction energies near the Brillouin zone centre, Avv(n + Bvv(n|k|2, is analysed. As shown, Avv(n  0 and Bvv(n  0 along all the high-symmetry [100], [110], [111] directions in reciprocal space for f.c.c. crystals with negative anisotropy factor. The criterion of modulated-structure formation for interacting vacancies in f.c.c. crystals is considered. Dependence of the f.c.c.-Ni–vacancies modulated-structure period on temperature is plotted. The effective vacancy–vacancy interaction is considered. Based on the continuum approximation for the Fourier components of strain-induced vacancy–vacancy-interaction energies, approximating expressions for their expansion coefficients are obtained, depending on the elasticity moduli, longitudinal and transverse phonon frequencies, and vacancy-concentration-dependent lattice parameter. A non-analytical behaviour of the k-dependent Fourier components of the strain-induced vacancy–vacancy-interaction energies near the Brillouin zone centre, Avv(n + Bvv(n|k|2, is analysed. As shown, Avv(n  0 and Bvv(n  0 along all the high-symmetry [100], [110], [111] directions in reciprocal space for f.c.c. crystals with negative anisotropy factor. The criterion of modulated-structure formation for interacting vacancies in f.c.c. crystals is considered. Dependence of the f.c.c.-Ni–vacancies modulated-structure period on temperature is plotted. The effective vacancy–vacancy interaction is considered

  12. 钎焊工艺参数对C/C复合材料/Cu/Mo/TC4钎焊接头微观组织的影响%Effects of Brazing Parameters on Microstructures of C/C Composite/Cu/Mo/TC4 Brazed Joints

    Institute of Scientific and Technical Information of China (English)

    秦优琼; 于治水


    在钎焊温度为820~940℃,钎焊时间为1~30min的条件下,采用TiZrNiCu钎料、Cu/Mo复合中间层对C/C复合材料和TC4进行了钎焊实验.利用扫描电镜及能谱仪对接头的界面组织进行了研究.结果表明:在较低工艺参数下,Cu/C/C复合材料界面结构为Cu/Cu51Zr14/Ti2 (Cu,Ni)+ Ti(Cu,Ni)+ TiCu+ Cu2TiZr/TiC/C/C复合材料.随着工艺参数的提高,TiCu和Cu2TiZr反应相逐渐消失,Ti(Cu,Ni)2新相生成,此时的界面结构为Cu/Cu51Zr14/Ti2 (Cu,Ni)+ Ti(Cu,Ni)+Ti(Cu,Ni)2/TiC/C/C复合材料.钎焊工艺参数较高时界面结构为Cu/Cu51Zr14/Cu(s.s)+Ti(Cu,Ni)2/TiC/C/C复合材料.随着钎焊温度的增加以及保温时间的延长,界面反应层Cu51Zr14和TiC反应层厚度增加.%C/C composite and TC4 were brazed using TiZrNiCu filler metal and Cu/Mo composite in-terlayers at 820-940℃ for l-30min. The interfacial microstructures were investigated by scanning electron microscopy and electron energy spectrum analysis. The results showed that the sequence of the interface structure at low brazing parameters can be described as the following: Cu/Cu51Zr14/Ti2 (Cu, Ni)+Ti(Cu,Ni)+TiCu+Cu2TiZr/TiC/C/C composite. With the increased brazing parameter, TiCu and Cu2TiZr disappeared, and Ti(Cu,Ni)2 appeared. The interface structure was changed to Cu/Cu5i Zri4/Ti2 (Cu,Ni)+Ti(Cu,Ni)+ Ti(Cu,Ni)2/TiC/C/C composite. For high brazing parameters, the interface structure was composed of Cu/Cu51 Zr14/Cu(s. s) + Ti(Cu, Ni)2/TiC/C/C composite. The thickness of Cu51Zr14and TiC reaction layers increased with the increased brazing temperature and the prolonged holding time.

  13. Application of C/C Composites in Rocket Engine Nozzles in Japan%日本火箭发动机喷管用C/C复合材料

    Institute of Scientific and Technical Information of China (English)

    李崇俊; 崔红; 李瑞珍


    The application state of C/C composites in solid rocket motor nozzle in Japan.The components include a rosetta carbon fabric laminated 2D-C/C exit cone for satellite apogee boost motor,and 3D-C/C throat inserts for solid rocket booster and launch vehicle.The rayon based carbon fiber is adopted to make the 2D-C/C exit cone.The 3D-C/C throat insert,used as the 1st stage of M-V solid rocket launch vehicle,has a dimension of Фll00 mm in outer diameter and a density of 1.95 g/em3.The 3 D preform is orthogonally weaved in a cylinder structure,and then densified by a repeating heat isostatic pressure-graphitization cycles.Applications of C/C composites in both solid and liquid rocket motor nozzle extendable exit cones are future development trend in this area.%介绍了C/C复合材料在日本固体火箭发动机喷管的应用情况,主要包括卫星远地点助推发动机用螺旋形状碳布铺层的2D-C/C扩张段、固体助推器及固体运载用3D-C/C喉衬.2D-C/C扩张段采用黏胶丝基碳纤维成型,M-V固体运载一级发动机C/C喉衬采用碳纤维三向正交圆筒编织结构,热等静压-石墨化致密,外径Ф1100 mm,密度达1.95 g/cm3.C/C复合材料在固体及液体火箭发动机喷管延伸出口锥的应用是未来的发展方向.

  14. What factors influence the reactivity of C-H hydroxylation and C=C epoxidation by [Fe(IV)(L(ax))(1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane)(O)](n+). (United States)

    Yi, Wang; Yuan, Liu; Kun, Yang; Zhengwen, He; Jing, Tian; Xu, Fei; Hong, Guo; Yong, Wang


    Density functional theory is used to investigate geometric structures and mechanisms for hydroxylation and epoxidation from propene for four non-heme iron complexes, [Fe(IV)(L(ax))(TMC)(O)](n+), which are the inverted isomers of [Fe(IV)(O)(TMC)(Lax)](n+) (Lax = acetonitrile (AN), monoanionic trifluoroacetate (TF), azide (N3), thiolate (SR)). The Fe(IV)O unit is found to be sterically less hindered in [Fe(IV)(L(ax))(TMC)(O)](n+) than that in [Fe(IV)(O)(TMC)(L(ax))](n+). Becke, three-parameter, Lee-Yang-Parr (B3LYP) calculations show that hydroxylation and epoxidation proceed via a two-state-reactivity on competing triplet and quintet spin surfaces; and the reactions have been invariably mediated by the S = 2 state. The reaction pathways computed reveal that 2-AN is the most reactive in the four [Fe(IV)(L(ax))(TMC)(O)](n+) complexes; along the reaction pathway, the axial ligand moves away from the iron center, and thus, the energy of the LUMO decreases. The anionic axial ligand, which is more electron releasing than neutral AN, shows a strong overlap of iron orbitals. Thus, the anionic ligand does not move away from the iron center. The H-abstraction is affected by the tunneling contribution, the more electron donation power of the axial ligand, the more effect of the tunneling contribution. Adding the tunneling correction, the relative reactivity of the hydroxylation follows the trend: 2-AN > 2-SR ≈ 2-N3 > 2-TF. However, for the epoxidation, the reactivity is in the following order of 2-AN > 2-TF > 2-N3 > 2-SR. Except for 2-AN, 2-X (L(ax) = TF, N3, SR) complexes chemoselectively hydroxylate even in the presence of a C=C double bond.

  15. The effect of applied stress on damage mode of 3D C/C composites under bend-bend fatigue loading

    Institute of Scientific and Technical Information of China (English)

    LIAO XiaoLing; LI HeJun; XU WenFeng; LI KeZhi


    The bend-bend fatigue behavior of 3D integral braided carbon/carbon composites (3D C/C) was examined. Fatigue test was conducted under load control at a sinusoidal frequency of 10 Hz to obtain stress-fracture cycles (S-N) relationship. The fatigue limit of the C/C was found to be 203 MPa (92% of the static flexural strength), the lag loops of fatigue load-displacement were transformed from elasticity to anelasticity and the flexibility of specimens were enhanced with increase in applied stress. It is revealed that the interfacial sliding abrasion played an important role in the fatigue failure process, and the extent and speed of sliding abrasion were controlled by the level of applied stress.

  16. Isolation and characterization of Exodus-2, a novel C-C chemokine with a unique 37-amino acid carboxyl-terminal extension. (United States)

    Hromas, R; Kim, C H; Klemsz, M; Krathwohl, M; Fife, K; Cooper, S; Schnizlein-Bick, C; Broxmeyer, H E


    Chemokines are a group of small, homologous proteins that regulate leukocyte migration, hemopoiesis, and HIV-1 absorption. We report here the cloning and characterization of a novel murine and human C-C chemokine termed Exodus-2 for its similarity to Exodus-1/MIP-3alpha/LARC, and its chemotactic ability. This novel chemokine has a unique 36 or 37 (murine and human, respectively) amino acid carboxyl-terminal extension not seen in any other chemokine family member. Purified recombinant Exodus-2 was found to have two activities classically associated with chemokines: inhibiting hemopoiesis and stimulating chemotaxis. However, Exodus-2 also had unusual characteristics for C-C chemokines. It selectively stimulated the chemotaxis of T-lymphocytes and was preferentially expressed in lymph node tissue. The combination of these characteristics may be a functional correlate for the unique carboxyl-terminal structure of Exodus-2.

  17. Esercizio dell’attività di impresa in forma societaria e disciplina di cui all’art. 230-bis c.c.: sull’asserita incompatibilità

    Directory of Open Access Journals (Sweden)

    Luigi Balestra


    Full Text Available Le Sezioni Unite (Cass., sez un., 6 novembre 2014, n. 23676 Rel. Bernabai già segnalata in questa Rivista hanno risolto il conflitto, profilatosi innanzi alla Sezione lavoro agli inizi del nuovo millennio, in ordine alla portata applicativa dell’art. 230-bis c.c., essendo state chiamate a stabilire se la fattispecie compendiata dalla norma in questione presupponga necessariamente un imprenditore persona fisica – elemento per vero non enunciato esplicitamente dalla disposizione, ma ricavabile dal comma 3 dell’art. 230-bis c.c. ove v’è il riferimento a un vincolo (di coniugio, parentela o affinità configurabile solo tra persone fisiche – o se, invece, sia prospettabile anche quando l’attività di impresa venga svolta in forma societaria.

  18. Tests of C P T symmetry in B0-B¯ 0 mixing and in B0→c c ¯K0 decays (United States)

    Lees, J. P.; Poireau, V.; Tisserand, V.; Grauges, E.; Palano, A.; Eigen, G.; Brown, D. N.; Kolomensky, Yu. G.; Koch, H.; Schroeder, T.; Hearty, C.; Mattison, T. S.; McKenna, J. A.; So, R. Y.; Blinov, V. E.; Buzykaev, A. R.; Druzhinin, V. P.; Golubev, V. B.; Kravchenko, E. A.; Onuchin, A. P.; Serednyakov, S. I.; Skovpen, Yu. I.; Solodov, E. P.; Todyshev, K. Yu.; Lankford, A. J.; Gary, J. W.; Long, O.; Eisner, A. M.; Lockman, W. S.; Panduro Vazquez, W.; Chao, D. S.; Cheng, C. H.; Echenard, B.; Flood, K. T.; Hitlin, D. G.; Kim, J.; Miyashita, T. S.; Ongmongkolkul, P.; Porter, F. C.; Röhrken, M.; Huard, Z.; Meadows, B. T.; Pushpawela, B. G.; Sokoloff, M. D.; Sun, L.; Smith, J. G.; Wagner, S. R.; Bernard, D.; Verderi, M.; Bettoni, D.; Bozzi, C.; Calabrese, R.; Cibinetto, G.; Fioravanti, E.; Garzia, I.; Luppi, E.; Santoro, V.; Calcaterra, A.; de Sangro, R.; Finocchiaro, G.; Martellotti, S.; Patteri, P.; Peruzzi, I. M.; Piccolo, M.; Zallo, A.; Passaggio, S.; Patrignani, C.; Bhuyan, B.; Mallik, U.; Chen, C.; Cochran, J.; Prell, S.; Ahmed, H.; Gritsan, A. V.; Arnaud, N.; Davier, M.; Le Diberder, F.; Lutz, A. M.; Wormser, G.; Lange, D. J.; Wright, D. M.; Coleman, J. P.; Gabathuler, E.; Hutchcroft, D. E.; Payne, D. J.; Touramanis, C.; Bevan, A. J.; di Lodovico, F.; Sacco, R.; Cowan, G.; Banerjee, Sw.; Brown, D. N.; Davis, C. L.; Denig, A. G.; Fritsch, M.; Gradl, W.; Griessinger, K.; Hafner, A.; Schubert, K. R.; Barlow, R. J.; Lafferty, G. D.; Cenci, R.; Jawahery, A.; Roberts, D. A.; Cowan, R.; Cheaib, R.; Robertson, S. H.; Dey, B.; Neri, N.; Palombo, F.; Cremaldi, L.; Godang, R.; Summers, D. J.; Taras, P.; de Nardo, G.; Sciacca, C.; Raven, G.; Jessop, C. P.; Losecco, J. M.; Honscheid, K.; Kass, R.; Gaz, A.; Margoni, M.; Posocco, M.; Rotondo, M.; Simi, G.; Simonetto, F.; Stroili, R.; Akar, S.; Ben-Haim, E.; Bomben, M.; Bonneaud, G. R.; Calderini, G.; Chauveau, J.; Marchiori, G.; Ocariz, J.; Biasini, M.; Manoni, E.; Rossi, A.; Batignani, G.; Bettarini, S.; Carpinelli, M.; Casarosa, G.; Chrzaszcz, M.; Forti, F.; Giorgi, M. A.; Lusiani, A.; Oberhof, B.; Paoloni, E.; Rama, M.; Rizzo, G.; Walsh, J. J.; Smith, A. J. S.; Anulli, F.; Faccini, R.; Ferrarotto, F.; Ferroni, F.; Pilloni, A.; Piredda, G.; Bünger, C.; Dittrich, S.; Grünberg, O.; Heß, M.; Leddig, T.; Voß, C.; Waldi, R.; Adye, T.; Wilson, F. F.; Emery, S.; Vasseur, G.; Aston, D.; Cartaro, C.; Convery, M. R.; Dorfan, J.; Dunwoodie, W.; Ebert, M.; Field, R. C.; Fulsom, B. G.; Graham, M. T.; Hast, C.; Innes, W. R.; Kim, P.; Leith, D. W. G. S.; Luitz, S.; Luth, V.; Macfarlane, D. B.; Muller, D. R.; Neal, H.; Ratcliff, B. N.; Roodman, A.; Sullivan, M. K.; Va'Vra, J.; Wisniewski, W. J.; Purohit, M. V.; Wilson, J. R.; Randle-Conde, A.; Sekula, S. J.; Bellis, M.; Burchat, P. R.; Puccio, E. M. T.; Alam, M. S.; Ernst, J. A.; Gorodeisky, R.; Guttman, N.; Peimer, D. R.; Soffer, A.; Spanier, S. M.; Ritchie, J. L.; Schwitters, R. F.; Izen, J. M.; Lou, X. C.; Bianchi, F.; de Mori, F.; Filippi, A.; Gamba, D.; Lanceri, L.; Vitale, L.; Martinez-Vidal, F.; Oyanguren, A.; Albert, J.; Beaulieu, A.; Bernlochner, F. U.; King, G. J.; Kowalewski, R.; Lueck, T.; Nugent, I. M.; Roney, J. M.; Tasneem, N.; Gershon, T. J.; Harrison, P. F.; Latham, T. E.; Prepost, R.; Wu, S. L.; Babar Collaboration


    Using the eight time dependences e-Γ t(1 +Cicos Δ m t +Sisin Δ m t ) for the decays Υ (4 S )→B0B¯0→fjfk, with the decay into a flavor-specific state fj=ℓ±X before or after the decay into a C P eigenstate fk=c c ¯KS ,L, as measured by the BABAR experiment, we determine the three C P T -sensitive parameters Re (z ) and Im (z ) in B 0-B¯ 0 mixing and |A ¯/A | in B0→c c ¯K0 decays. We find Im (z )=0.010 ±0.030 ±0.013 , Re (z )=-0.065 ±0.028 ±0.014 , and |A ¯/A |=0.999 ±0.023 ±0.017 , in agreement with C P T symmetry.

  19. The effect of applied stress on damage mode of 3D C/C composites under bend-bend fatigue loading

    Institute of Scientific and Technical Information of China (English)


    The bend-bend fatigue behavior of 3D integral braided carbon/carbon composites (3D C/C) was examined. Fatigue test was conducted under load control at a sinu-soidal frequency of 10 Hz to obtain stress-fracture cycles (S-N) relationship. The fatigue limit of the C/C was found to be 203 MPa (92% of the static flexural strength), the lag loops of fatigue load-displacement were transformed from elasticity to anelasticity and the flexibility of specimens were enhanced with increase in applied stress. It is revealed that the interfacial sliding abrasion played an important role in the fatigue failure process, and the extent and speed of sliding abrasion were con-trolled by the level of applied stress.

  20. Effects of C/C composites on the irradiation of activation foil%炭/炭复合材料对活化片辐照的影响

    Institute of Scientific and Technical Information of China (English)

    周雪梅; 孟令杰; 赖伟


    Background: C/C composites coated with SiC were introduced for the irradiation measurement at high temperature in Thorium Molten Salt Reactor-Solid Fuel (TMSR-SF) due to their excellent performance as an irradiation carrier of activation foil.Purpose:This study aims at the effects of C/C composites to activation foils. Methods:Based on the characteristics and service environment of C/C composites, component test and thermos analysis were carried out by element gravimetric density (GD) and calorimeter respectively to verify whether they would have influence on the irradiation results. Neutron irradiation experiment for activation foils with/without C/C composites was performed in a horizontal radial hole of uranium zirconium hydride reactor. And the activation rates of mononuclear were calculated respectively. Results: Experimental results show that SiC coating is essential for C/C composites to enhance oxidation resistance. The activation rate of mononuclear with C/C compositeswas reduced slightly. When the thickness of C/Cwas of mm-level, the decrement ofactivation rate for mononuclear was less than 10%.Conclusion:C/C composites coated with SiC could be used as carrier materials for activation foils at high temperature when the carrier wall is thin. The results of irradiation could be corrected based on the measurement of C/C composites.%根据钍基熔盐堆高温环境辐射测量需求,采用具有高温抗氧化SiC涂层的炭/炭复合材料作为待测活化片的载体材料,介绍了采用炭/炭复合材料作为辐照载体的优越性,对其进行了成分和热分析测试,并详细描述了带有炭/炭复合材料的一组活化片和不带有炭/炭复合材料的另一组活化片同时在铀氢锆脉冲堆的径向实验孔道中进行中子辐照的实验过程.通过比较两组活化片的单核反应率,详细分析了炭/炭复合材料对活化片辐照结果的影响.结果表明,载体采用涂层为SiC的炭/炭复合材料,并且壁厚

  1. Log ASCII Standard (LAS) Files for Geophysical (Gamma Ray) Wireline Well Logs and Their Application to Geologic Cross Section C-C' Through the Central Appalachian Basin (United States)

    Trippi, Michael H.; Crangle, Robert D.


    U.S. Geological Survey (USGS) regional geologic cross section C-C' (Ryder and others, 2008) displays key stratigraphic intervals in the central Appalachian basin. For this cross section, strata were correlated by using descriptions of well cuttings and gamma ray well log traces. This report summarizes the procedures used to convert gamma ray curves on paper well logs to the digital Log ASCII (American Standard Code for Information Interchange) Standard (LAS) format using the third-party software application Neuralog. The procedures could be used with other geophysical wireline logs also. The creation of digital LAS files from paper well logs by using Neuralog is very helpful, especially when dealing with older logs with limited or nonexistent digital data. The LAS files from the gamma ray logs of 11 wells used to construct cross section C-C' are included in this report. They may be downloaded from the index page as a single ZIP file.

  2. Chemokine (C-C motif) Ligand 2 is a potential biomarker of inflammation & physical fitness in obese children: a cross-sectional study


    Samaan, M Constantine; Obeid, Joyce; Nguyen, Thanh,; Thabane, Lehana; Timmons, Brian W


    Background Obesity is a global epidemic that is impacting children around the world. Obesity is a chronic inflammatory state with enhanced production of multiple cytokines and chemokines. Chemokine (C-C motif) Ligand 2 (CCL2) is produced by immune and metabolic cells and attracts immune cells into liver, muscle and adipose tissue, resulting in initiation and propagation of the inflammatory response in obesity. How obesity and fitness affect the production of this chemokine in children is unkn...

  3. Highly stable organic monolayers for reacting silicon with further functionalities: the effect of the C-C bond nearest the silicon surface. (United States)

    Puniredd, Sreenivasa Reddy; Assad, Ossama; Haick, Hossam


    Crystalline Si(111) surfaces have been alkylated in a two-step chlorination/alkylation process using various organic molecules having similar backbones but differing in their C-C bond closest to the silicon surface (i.e., C-C vs C=C vs C[triple bond]C bonds). X-ray photoelectron spectroscopic (XPS) data show that functionalization of silicon surfaces with propenyl magnesium bromide (CH3-CH=CH-MgBr) organic molecules gives nearly full coverage of the silicon atop sites, as on methyl- and propynyl-terminated silicon surfaces. Propenyl-terminated silicon surface shows less surface oxidation and is more robust against solvent attacks when compared to methyl- and propynyl-terminated silicon surfaces. We also show a secondary functionalization process of propenyl-terminated silicon surface with 4'-[3-Trifluoromethyl-3H-diazirin-3-yl]-benzoic acid N-hydroxysuccinimide ester [TDBA-OSu] cross-linker. The Si-CH=CH-CH3 surfaces thus offer a means of attaching a variety of chemical moieties to a silicon surface through a short linking group, enabling applications in molecular electronics, energy conversion, catalysis, and sensing.

  4. Active Metal Brazing and Characterization of Brazed Joints in C-C and C-SiC Composites to Copper-Clad-Molybdenum System (United States)

    Singh, M.; Asthana, R.


    Carbon/carbon composites with CVI and resin-derived matrices, and C/SiC composites reinforced with T-300 carbon fibers in a CVI SiC matrix were joined to Cu-clad Mo using two Ag-Cu braze alloys, Cusil-ABA (1.75% Ti) and Ticusil (4.5% Ti). The brazed joints revealed good interfacial bonding, preferential precipitation of Ti at the composite/braze interface, and a tendency toward delamination in resin-derived C/C composite. Extensive braze penetration of the inter-fiber channels in the CVI C/C composites was observed. The Knoop microhardness (HK) distribution across the C/C joints indicated sharp gradients at the interface, and a higher hardness in Ticusil than in Cusil-ABA. For the C/SiC composite to Cu-clad-Mo joints, the effect of composite surface preparation revealed that ground samples did not crack whereas unground samples cracked. Calculated strain energy in brazed joints in both systems is comparable to the strain energy in a number of other ceramic/metal systems. Theoretical predictions of the effective thermal resistance suggest that such joined systems may be promising for thermal management applications.

  5. Robust electrodes based on coaxial TiC/C-MnO2 core/shell nanofiber arrays with excellent cycling stability for high-performance supercapacitors. (United States)

    Zhang, Xuming; Peng, Xiang; Li, Wan; Li, Limin; Gao, Biao; Wu, Guosong; Huo, Kaifu; Chu, Paul K


    A coaxial electrode structure composed of manganese oxide-decorated TiC/C core/shell nanofiber arrays is produced hydrothermally in a KMnO4 solution. The pristine TiC/C core/shell structure prepared on the Ti alloy substrate provides the self-sacrificing carbon shell and highly conductive TiC core, thus greatly simplifying the fabrication process without requiring an additional reduction source and conductive additive. The as-prepared electrode exhibits a high specific capacitance of 645 F g(-1) at a discharging current density of 1 A g(-1) attributable to the highly conductive TiC/C and amorphous MnO2 shell with fast ion diffusion. In the charging/discharging cycling test, the as-prepared electrode shows high stability and 99% capacity retention after 5000 cycles. Although the thermal treatment conducted on the as-prepared electrode decreases the initial capacitance, the electrode undergoes capacitance recovery through structural transformation from the crystalline cluster to layered birnessite type MnO2 nanosheets as a result of dissolution and further electrodeposition in the cycling. 96.5% of the initial capacitance is retained after 1000 cycles at high charging/discharging current density of 25 A g(-1). This study demonstrates a novel scaffold to construct MnO2 based SCs with high specific capacitance as well as excellent mechanical and cycling stability boding well for future design of high-performance MnO2-based SCs.

  6. Improvement of MS (multiple sclerosis) CAD (computer aided diagnosis) performance using C/C++ and computing engine in the graphical processing unit (GPU) (United States)

    Suh, Joohyung; Ma, Kevin; Le, Anh


    Multiple Sclerosis (MS) is a disease which is caused by damaged myelin around axons of the brain and spinal cord. Currently, MR Imaging is used for diagnosis, but it is very highly variable and time-consuming since the lesion detection and estimation of lesion volume are performed manually. For this reason, we developed a CAD (Computer Aided Diagnosis) system which would assist segmentation of MS to facilitate physician's diagnosis. The MS CAD system utilizes K-NN (k-nearest neighbor) algorithm to detect and segment the lesion volume in an area based on the voxel. The prototype MS CAD system was developed under the MATLAB environment. Currently, the MS CAD system consumes a huge amount of time to process data. In this paper we will present the development of a second version of MS CAD system which has been converted into C/C++ in order to take advantage of the GPU (Graphical Processing Unit) which will provide parallel computation. With the realization of C/C++ and utilizing the GPU, we expect to cut running time drastically. The paper investigates the conversion from MATLAB to C/C++ and the utilization of a high-end GPU for parallel computing of data to improve algorithm performance of MS CAD.

  7. Construction and identification of recombinant Mycobacterium smegmatis vaccine expressing Cysticercus cellulosae cC1 antigen%猪囊尾蚴特异性抗原cC1重组耻垢分枝杆菌疫苗的构建与鉴定

    Institute of Scientific and Technical Information of China (English)

    王雪梅; 骆江坤; 李倩; 李江艳; 陈勇; 陶志勇; 夏惠; 方强


    Objective To construct recombinant Mycobacterium smegmatis vaccine expressing Cysticercus cellulosae cC1 anti-gen. Methods The recombinant pET28a-cC1 plasmid was extracted and double digested by Xho I and BamH I restriction en-zymes,and shuttle plasmid pMV261 was extracted and double digested by Hind III and BamH I restriction enzymes. Both frag-ments were modified by Klenow fragment to form blunt end,then the large fragments of cC1 and pMV261 plasmid were purified and ligated by T4 ligase enzyme. The recombinant pMV261-cC1 plasmid was constructed and sequenced. Then the pMV261-cC1 plasmid was transformed into Mycobacterium smegmatis by the electrotransformation method. The recombinant cC1-Mycobacterium smegmatis was induced by heat and identified by the Western blotting method with the sera of cysticercosis patients. In addition, the growth states of the Mycobacterium smegmatis and the recombinant cC1-Mycobacterium smegmatis were compared and the growth curves were drawn. Results The restriction enzyme and sequencing results showed that the recombinant pMV261-cC1 plasmid was successfully constructed. After heat induction,a 40 kD band was showed by PAGE analysis of cC1-Mycobacterium smegmatis. The Western blotting results showed that the sera of cysticercosis patients could recognize the 40 kDa band,which sug-gested that cC1 protein was expressed in Mycobacterium smegmatis. Compared with the Mycobacterium smegmatis,the recombi-nant cC1-Mycobacterium smegmatis showed no significant difference in proliferation characteristics. Conclusion The recombi-nant cC1-Mycobacterium smegmatis vaccine has been successfully constructed.%目的:构建表达猪囊尾蚴cC1抗原的重组耻垢分枝杆菌疫苗。方法提取pET28a-cC1质粒DNA,用xho I和BamH I双酶切,用Klenow酶补平xho I酶切末端,同时提取pMV261穿梭质粒载体,用Hind III和BamH I双酶切,用Klenow酶补平Hind III酶切末端,纯化后的酶切产物通过T4

  8. A Substrate-Assisted Mechanism of Nucleophile Activation in a Ser-His-Asp Containing C-C Bond Hydrolase

    Energy Technology Data Exchange (ETDEWEB)

    Ruzzini, Antonio C.; Bhowmik, Shiva; Ghosh, Subhangi; Yam, Katherine C.; Bolin, Jeffrey T.; Eltis, Lindsay D. [Purdue; (UBC)


    The meta-cleavage product (MCP) hydrolases utilize a Ser–His–Asp triad to hydrolyze a carbon–carbon bond. Hydrolysis of the MCP substrate has been proposed to proceed via an enol-to-keto tautomerization followed by a nucleophilic mechanism of catalysis. Ketonization involves an intermediate, ESred, which possesses a remarkable bathochromically shifted absorption spectrum. We investigated the catalytic mechanism of the MCP hydrolases using DxnB2 from Sphingomonas wittichii RW1. Pre-steady-state kinetic and LC ESI/MS evaluation of the DxnB2-mediated hydrolysis of 2-hydroxy-6-oxo-6-phenylhexa-2,4-dienoic acid to 2-hydroxy-2,4-pentadienoic acid and benzoate support a nucleophilic mechanism catalysis. In DxnB2, the rate of ESred decay and product formation showed a solvent kinetic isotope effect of 2.5, indicating that a proton transfer reaction, assigned here to substrate ketonization, limits the rate of acylation. For a series of substituted MCPs, this rate was linearly dependent on MCP pKa2nuc ~ 1). Structural characterization of DxnB2 S105A:MCP complexes revealed that the catalytic histidine is displaced upon substrate-binding. The results provide evidence for enzyme-catalyzed ketonization in which the catalytic His–Asp pair does not play an essential role. The data further suggest that ESred represents a dianionic intermediate that acts as a general base to activate the serine nucleophile. This substrate-assisted mechanism of nucleophilic catalysis distinguishes MCP hydrolases from other serine hydrolases.

  9. Temperature dependent product yields for the spin forbidden singlet channel of the C(3P) + C2H2 reaction (United States)

    Hickson, Kevin M.; Loison, Jean-Christophe; Wakelam, Valentine


    The atomic hydrogen formation channels of the C + C2H2 reaction have been investigated using a continuous supersonic flow reactor over the 52-296 K temperature range. H-atoms were detected directly at 121.567 nm by vacuum ultraviolet laser induced fluorescence. Absolute H-atom yields were determined by comparison with the H-atom signal generated by the C + C2H4 reaction. The product yields agree with earlier crossed beam experiments employing universal detection methods. Incorporating these branching ratios in a gas-grain model of dense interstellar clouds increases the c-C3H abundance. This reaction is a minor source of C3-containing molecules in the present simulations.

  10. Temperature Dependent Product Yields for the Spin Forbidden Singlet Channel of the C(3P) + C2H2 Reaction

    CERN Document Server

    Hickson, Kevin M; Wakelam, Valentine


    The atomic hydrogen formation channels of the C + C2H2 reaction have been investigated using a continuous supersonic flow reactor over the 52 K 296 K temperature range. H-atoms were detected directly at 121.567 nm by vacuum ultraviolet laser induced fluorescence. Absolute H-atom yields were determined by comparison with the H-atom signal generated by the C + C2H4 reaction. The product yields agree with earlier crossed beam experiments employing universal detection methods. Incorporating these branching ratios in a gas-grain model of dense interstellar clouds increases the cC3H abundance. This reaction is a minor source of C3 containing molecules in the present simulations.

  11. Reaction of β-enaminones and acetylene dicarboxylates: synthesis of substituted 1,2-dihydropyridinones. (United States)

    Nagaraju, Vemu; Purnachander, Dalovai; Mangina, N S V M Rao; Suresh, Surisetti; Sridhar, Balasubramanian; Karunakar, Galla V


    Synthesis of substituted 1,2-dihydropyridinones is described in a one pot reaction of β-enaminones and acetylene dicarboxylates where new C-C and C-N bonds were formed. The title compounds were obtained in moderate to good yields.

  12. Catalysis of Photochemical Reactions. (United States)

    Albini, A.


    Offers a classification system of catalytic effects in photochemical reactions, contrasting characteristic properties of photochemical and thermal reactions. Discusses catalysis and sensitization, examples of catalyzed reactions of excepted states, complexing ground state substrates, and catalysis of primary photoproducts. (JM)

  13. Chiral amide from (1, 2)-(+)-norephedrine and furoic acid: An efficient catalyst for asymmetric Reformatsky reaction

    Indian Academy of Sciences (India)

    Nallamuthu Ananthi; Sivan Velmathi


    Chiral amide derived from (1, 2)-(+)-norephedrine and 2-furoic acid was found to catalyse the asymmetric Reformatsky reaction between prochiral aldehydes and α-bromo ethylacetate with diethylzinc as zinc source. The corresponding chiral -hydroxy esters were formed in 99% yield with over 80% enantiomeric excess. The presence of air was found to be essential for the effective C-C bond formation. The mechanism for the catalytic reaction was proposed.

  14. [Allergic reactions to transfusion]. (United States)

    Hergon, E; Paitre, M L; Coeffic, B; Piard, N; Bidet, J M


    Frequent allergic reactions following transfusion are observed. Usually, they are benign but sometimes we observe severe allergic reactions. Adverse reactions may be brought about by least two mechanisms. First, immediate-type hypersensibility reactions due to IgE. Secondly, anaphylactic-type reactions due to interaction between transfused IgA and class specific anti IgA in the recipient's plasma. They are characterized by their severest form (anaphylactic shock). The frequency of severe reactions following the transfusion blood plasma is very low. These transfusion reactions are complement-mediated and kinins-mediated. Prevention of allergic reactions is necessary among blood donors and recipients.

  15. Insights into the Competing Mechanisms and Origin of Enantioselectivity for N-Heterocyclic Carbene-Catalyzed Reaction of Aldehyde with Enamide (United States)

    Qiao, Yan; Chen, Xinhuan; Wei, Donghui; Chang, Junbiao


    Hydroacylation reactions and aza-benzoin reactions have attracted considerable attention from experimental chemists. Recently, Wang et al. reported an interesting reaction of N-heterocyclic carbene (NHC)-catalyzed addition of aldehyde to enamide, in which both hydroacylation and aza-benzoin reactions may be involved. Thus, understanding the competing relationship between them is of great interest. Now, density functional theory (DFT) investigation was performed to elucidate this issue. Our results reveal that enamide can tautomerize to its imine isomer with the assistance of HCO3‑. The addition of NHC to aldehydes formed Breslow intermediate, which can go through cross-coupling with enamide via hydroacylation reaction or its imine isomer via aza-benzoin reaction. The aza-benzoin reaction requires relatively lower free energy barrier than the hydroacylation reaction. The more polar characteristic of C=N group in the imine isomers, and the more advantageous stereoelectronic effect in the carbon-carbon bond forming transition states in aza-benzoin pathway were identified to determine that the imine isomer can react with the Breslow intermediate more easily. Furthermore, the origin of enantioselectivities for the reaction was explored and reasonably explained by structural analyses on key transition states. The work should provide valuable insights for rational design of switchable NHC-catalyzed hydroacylation and aza-benzoin reactions with high stereoselectivity.



    Castaño-Molina, Jorge Eliecer


    En el mercado de artes gráficas de la ciudad Santiago de Cali, con la empresa C&C GRÁFICAS Ltda. ha entrado en el reto de asumir, la propuesta documental de su organización, desde la concepción de su planeación estratégica para seguridad y salud ocupacional, la política, la caracterización de procesos y procedimientos estandarizados e instrucciones técnicas para cumplir con un sistema de gestión en S&SO Se analiza el contexto organizacional, el entorno, la legislación nacional (colombiana), l...

  17. Measurement of forward t t ‾, W + b b bar and W + c c bar production in pp collisions at √{ s} = 8 TeV (United States)

    Aaij, R.; Adeva, B.; Adinolfi, M.; Ajaltouni, Z.; Akar, S.; Albrecht, J.; Alessio, F.; Alexander, M.; Ali, S.; Alkhazov, G.; Alvarez Cartelle, P.; Alves, A. A.; Amato, S.; Amerio, S.; Amhis, Y.; An, L.; Anderlini, L.; Andreassi, G.; Andreotti, M.; Andrews, J. E.; Appleby, R. B.; Archilli, F.; d'Argent, P.; Arnau Romeu, J.; Artamonov, A.; Artuso, M.; Aslanides, E.; Auriemma, G.; Baalouch, M.; Babuschkin, I.; Bachmann, S.; Back, J. J.; Badalov, A.; Baesso, C.; Baker, S.; Baldini, W.; Barlow, R. J.; Barschel, C.; Barsuk, S.; Barter, W.; Baszczyk, M.; Batozskaya, V.; Batsukh, B.; Battista, V.; Bay, A.; Beaucourt, L.; Beddow, J.; Bedeschi, F.; Bediaga, I.; Bel, L. J.; Bellee, V.; Belloli, N.; Belous, K.; Belyaev, I.; Ben-Haim, E.; Bencivenni, G.; Benson, S.; Benton, J.; Berezhnoy, A.; Bernet, R.; Bertolin, A.; Betti, F.; Bettler, M.-O.; van Beuzekom, M.; Bezshyiko, Ia.; Bifani, S.; Billoir, P.; Bird, T.; Birnkraut, A.; Bitadze, A.; Bizzeti, A.; Blake, T.; Blanc, F.; Blouw, J.; Blusk, S.; Bocci, V.; Boettcher, T.; Bondar, A.; Bondar, N.; Bonivento, W.; Bordyuzhin, I.; Borgheresi, A.; Borghi, S.; Borisyak, M.; Borsato, M.; Bossu, F.; Boubdir, M.; Bowcock, T. J. V.; Bowen, E.; Bozzi, C.; Braun, S.; Britsch, M.; Britton, T.; Brodzicka, J.; Buchanan, E.; Burr, C.; Bursche, A.; Buytaert, J.; Cadeddu, S.; Calabrese, R.; Calvi, M.; Calvo Gomez, M.; Camboni, A.; Campana, P.; Campora Perez, D.; Campora Perez, D. H.; Capriotti, L.; Carbone, A.; Carboni, G.; Cardinale, R.; Cardini, A.; Carniti, P.; Carson, L.; Carvalho Akiba, K.; Casse, G.; Cassina, L.; Castillo Garcia, L.; Cattaneo, M.; Cauet, Ch.; Cavallero, G.; Cenci, R.; Charles, M.; Charpentier, Ph.; Chatzikonstantinidis, G.; Chefdeville, M.; Chen, S.; Cheung, S.-F.; Chobanova, V.; Chrzaszcz, M.; Cid Vidal, X.; Ciezarek, G.; Clarke, P. E. L.; Clemencic, M.; Cliff, H. V.; Closier, J.; Coco, V.; Cogan, J.; Cogneras, E.; Cogoni, V.; Cojocariu, L.; Collazuol, G.; Collins, P.; Comerma-Montells, A.; Contu, A.; Cook, A.; Coombs, G.; Coquereau, S.; Corti, G.; Corvo, M.; Costa Sobral, C. M.; Couturier, B.; Cowan, G. A.; Craik, D. C.; Crocombe, A.; Cruz Torres, M.; Cunliffe, S.; Currie, R.; D'Ambrosio, C.; Da Cunha Marinho, F.; Dall'Occo, E.; Dalseno, J.; David, P. N. Y.; Davis, A.; De Aguiar Francisco, O.; De Bruyn, K.; De Capua, S.; De Cian, M.; De Miranda, J. M.; De Paula, L.; De Serio, M.; De Simone, P.; Dean, C.-T.; Decamp, D.; Deckenhoff, M.; Del Buono, L.; Demmer, M.; Dendek, A.; Derkach, D.; Deschamps, O.; Dettori, F.; Dey, B.; Di Canto, A.; Dijkstra, H.; Dordei, F.; Dorigo, M.; Dosil Suárez, A.; Dovbnya, A.; Dreimanis, K.; Dufour, L.; Dujany, G.; Dungs, K.; Durante, P.; Dzhelyadin, R.; Dziurda, A.; Dzyuba, A.; Déléage, N.; Easo, S.; Ebert, M.; Egede, U.; Egorychev, V.; Eidelman, S.; Eisenhardt, S.; Eitschberger, U.; Ekelhof, R.; Eklund, L.; Elsasser, Ch.; Ely, S.; Esen, S.; Evans, H. M.; Evans, T.; Falabella, A.; Farley, N.; Farry, S.; Fay, R.; Fazzini, D.; Ferguson, D.; Fernandez Prieto, A.; Ferrari, F.; Ferreira Rodrigues, F.; Ferro-Luzzi, M.; Filippov, S.; Fini, R. A.; Fiore, M.; Fiorini, M.; Firlej, M.; Fitzpatrick, C.; Fiutowski, T.; Fleuret, F.; Fohl, K.; Fontana, M.; Fontanelli, F.; Forshaw, D. C.; Forty, R.; Franco Lima, V.; Frank, M.; Frei, C.; Fu, J.; Furfaro, E.; Färber, C.; Gallas Torreira, A.; Galli, D.; Gallorini, S.; Gambetta, S.; Gandelman, M.; Gandini, P.; Gao, Y.; Garcia Martin, L. M.; García Pardiñas, J.; Garra Tico, J.; Garrido, L.; Garsed, P. J.; Gascon, D.; Gaspar, C.; Gavardi, L.; Gazzoni, G.; Gerick, D.; Gersabeck, E.; Gersabeck, M.; Gershon, T.; Ghez, Ph.; Gianì, S.; Gibson, V.; Girard, O. G.; Giubega, L.; Gizdov, K.; Gligorov, V. V.; Golubkov, D.; Golutvin, A.; Gomes, A.; Gorelov, I. V.; Gotti, C.; Grabalosa Gándara, M.; Graciani Diaz, R.; Granado Cardoso, L. A.; Graugés, E.; Graverini, E.; Graziani, G.; Grecu, A.; Griffith, P.; Grillo, L.; Gruberg Cazon, B. R.; Grünberg, O.; Gushchin, E.; Guz, Yu.; Gys, T.; Göbel, C.; Hadavizadeh, T.; Hadjivasiliou, C.; Haefeli, G.; Haen, C.; Haines, S. C.; Hall, S.; Hamilton, B.; Han, X.; Hansmann-Menzemer, S.; Harnew, N.; Harnew, S. T.; Harrison, J.; Hatch, M.; He, J.; Head, T.; Heister, A.; Hennessy, K.; Henrard, P.; Henry, L.; Hernando Morata, J. A.; van Herwijnen, E.; Heß, M.; Hicheur, A.; Hill, D.; Hombach, C.; Hopchev, H.; Hulsbergen, W.; Humair, T.; Hushchyn, M.; Hussain, N.; Hutchcroft, D.; Idzik, M.; Ilten, P.; Jacobsson, R.; Jaeger, A.; Jalocha, J.; Jans, E.; Jawahery, A.; Jiang, F.; John, M.; Johnson, D.; Jones, C. R.; Joram, C.; Jost, B.; Jurik, N.; Kandybei, S.; Kanso, W.; Karacson, M.; Kariuki, J. M.; Karodia, S.; Kecke, M.; Kelsey, M.; Kenyon, I. R.; Kenzie, M.; Ketel, T.; Khairullin, E.; Khanji, B.; Khurewathanakul, C.; Kirn, T.; Klaver, S.; Klimaszewski, K.; Koliiev, S.; Kolpin, M.; Komarov, I.; Koopman, R. F.; Koppenburg, P.; Kosmyntseva, A.; Kozachuk, A.; Kozeiha, M.; Kravchuk, L.; Kreplin, K.; Kreps, M.; Krokovny, P.; Kruse, F.; Krzemien, W.; Kucewicz, W.; Kucharczyk, M.; Kudryavtsev, V.; Kuonen, A. K.; Kurek, K.; Kvaratskheliya, T.; Lacarrere, D.; Lafferty, G.; Lai, A.; Lambert, D.; Lanfranchi, G.; Langenbruch, C.; Latham, T.; Lazzeroni, C.; Le Gac, R.; van Leerdam, J.; Lees, J.-P.; Leflat, A.; Lefrançois, J.; Lefèvre, R.; Lemaitre, F.; Lemos Cid, E.; Leroy, O.; Lesiak, T.; Leverington, B.; Li, Y.; Likhomanenko, T.; Lindner, R.; Linn, C.; Lionetto, F.; Liu, B.; Liu, X.; Loh, D.; Longstaff, I.; Lopes, J. H.; Lucchesi, D.; Lucio Martinez, M.; Luo, H.; Lupato, A.; Luppi, E.; Lupton, O.; Lusiani, A.; Lyu, X.; Machefert, F.; Maciuc, F.; Maev, O.; Maguire, K.; Malde, S.; Malinin, A.; Maltsev, T.; Manca, G.; Mancinelli, G.; Manning, P.; Maratas, J.; Marchand, J. F.; Marconi, U.; Marin Benito, C.; Marino, P.; Marks, J.; Martellotti, G.; Martin, M.; Martinelli, M.; Martinez Santos, D.; Martinez Vidal, F.; Martins Tostes, D.; Massacrier, L. M.; Massafferri, A.; Matev, R.; Mathad, A.; Mathe, Z.; Matteuzzi, C.; Mauri, A.; Maurin, B.; Mazurov, A.; McCann, M.; McCarthy, J.; McNab, A.; McNulty, R.; Meadows, B.; Meier, F.; Meissner, M.; Melnychuk, D.; Merk, M.; Merli, A.; Michielin, E.; Milanes, D. A.; Minard, M.-N.; Mitzel, D. S.; Mogini, A.; Molina Rodriguez, J.; Monroy, I. A.; Monteil, S.; Morandin, M.; Morawski, P.; Mordà, A.; Morello, M. J.; Moron, J.; Morris, A. B.; Mountain, R.; Muheim, F.; Mulder, M.; Mussini, M.; Müller, D.; Müller, J.; Müller, K.; Müller, V.; Naik, P.; Nakada, T.; Nandakumar, R.; Nandi, A.; Nasteva, I.; Needham, M.; Neri, N.; Neubert, S.; Neufeld, N.; Neuner, M.; Nguyen, A. D.; Nguyen, T. D.; Nguyen-Mau, C.; Nieswand, S.; Niet, R.; Nikitin, N.; Nikodem, T.; Novoselov, A.; O'Hanlon, D. P.; Oblakowska-Mucha, A.; Obraztsov, V.; Ogilvy, S.; Oldeman, R.; Onderwater, C. J. G.; Otalora Goicochea, J. M.; Otto, A.; Owen, P.; Oyanguren, A.; Pais, P. R.; Palano, A.; Palombo, F.; Palutan, M.; Panman, J.; Papanestis, A.; Pappagallo, M.; Pappalardo, L. L.; Parker, W.; Parkes, C.; Passaleva, G.; Pastore, A.; Patel, G. D.; Patel, M.; Patrignani, C.; Pearce, A.; Pellegrino, A.; Penso, G.; Pepe Altarelli, M.; Perazzini, S.; Perret, P.; Pescatore, L.; Petridis, K.; Petrolini, A.; Petrov, A.; Petruzzo, M.; Picatoste Olloqui, E.; Pietrzyk, B.; Pikies, M.; Pinci, D.; Pistone, A.; Piucci, A.; Playfer, S.; Plo Casasus, M.; Poikela, T.; Polci, F.; Poluektov, A.; Polyakov, I.; Polycarpo, E.; Pomery, G. J.; Popov, A.; Popov, D.; Popovici, B.; Poslavskii, S.; Potterat, C.; Price, E.; Price, J. D.; Prisciandaro, J.; Pritchard, A.; Prouve, C.; Pugatch, V.; Puig Navarro, A.; Punzi, G.; Qian, W.; Quagliani, R.; Rachwal, B.; Rademacker, J. H.; Rama, M.; Ramos Pernas, M.; Rangel, M. S.; Raniuk, I.; Raven, G.; Redi, F.; Reichert, S.; dos Reis, A. C.; Remon Alepuz, C.; Renaudin, V.; Ricciardi, S.; Richards, S.; Rihl, M.; Rinnert, K.; Rives Molina, V.; Robbe, P.; Rodrigues, A. B.; Rodrigues, E.; Rodriguez Lopez, J. A.; Rodriguez Perez, P.; Rogozhnikov, A.; Roiser, S.; Rollings, A.; Romanovskiy, V.; Romero Vidal, A.; Ronayne, J. W.; Rotondo, M.; Rudolph, M. S.; Ruf, T.; Ruiz Valls, P.; Saborido Silva, J. J.; Sadykhov, E.; Sagidova, N.; Saitta, B.; Salustino Guimaraes, V.; Sanchez Mayordomo, C.; Sanmartin Sedes, B.; Santacesaria, R.; Santamarina Rios, C.; Santimaria, M.; Santovetti, E.; Sarti, A.; Satriano, C.; Satta, A.; Saunders, D. M.; Savrina, D.; Schael, S.; Schellenberg, M.; Schiller, M.; Schindler, H.; Schlupp, M.; Schmelling, M.; Schmelzer, T.; Schmidt, B.; Schneider, O.; Schopper, A.; Schubert, K.; Schubiger, M.; Schune, M.-H.; Schwemmer, R.; Sciascia, B.; Sciubba, A.; Semennikov, A.; Sergi, A.; Serra, N.; Serrano, J.; Sestini, L.; Seyfert, P.; Shapkin, M.; Shapoval, I.; Shcheglov, Y.; Shears, T.; Shekhtman, L.; Shevchenko, V.; Shires, A.; Siddi, B. G.; Silva Coutinho, R.; Silva de Oliveira, L.; Simi, G.; Simone, S.; Sirendi, M.; Skidmore, N.; Skwarnicki, T.; Smith, E.; Smith, I. T.; Smith, J.; Smith, M.; Snoek, H.; Sokoloff, M. D.; Soler, F. J. P.; Souza De Paula, B.; Spaan, B.; Spradlin, P.; Sridharan, S.; Stagni, F.; Stahl, M.; Stahl, S.; Stefko, P.; Stefkova, S.; Steinkamp, O.; Stemmle, S.; Stenyakin, O.; Stevenson, S.; Stoica, S.; Stone, S.; Storaci, B.; Stracka, S.; Straticiuc, M.; Straumann, U.; Sun, L.; Sutcliffe, W.; Swientek, K.; Syropoulos, V.; Szczekowski, M.; Szumlak, T.; T'Jampens, S.; Tayduganov, A.; Tekampe, T.; Tellarini, G.; Teubert, F.; Thomas, E.; van Tilburg, J.; Tilley, M. J.; Tisserand, V.; Tobin, M.; Tolk, S.; Tomassetti, L.; Tonelli, D.; Topp-Joergensen, S.; Toriello, F.; Tournefier, E.; Tourneur, S.; Trabelsi, K.; Traill, M.; Tran, M. T.; Tresch, M.; Trisovic, A.; Tsaregorodtsev, A.; Tsopelas, P.; Tully, A.; Tuning, N.; Ukleja, A.; Ustyuzhanin, A.; Uwer, U.; Vacca, C.; Vagnoni, V.; Valassi, A.; Valat, S.; Valenti, G.; Vallier, A.; Vazquez Gomez, R.; Vazquez Regueiro, P.; Vecchi, S.; van Veghel, M.; Velthuis, J. J.; Veltri, M.; Veneziano, G.; Venkateswaran, A.; Vernet, M.; Vesterinen, M.; Viaud, B.; Vieira, D.; Vieites Diaz, M.; Vilasis-Cardona, X.; Volkov, V.; Vollhardt, A.; Voneki, B.; Vorobyev, A.; Vorobyev, V.; Voß, C.; de Vries, J. A.; Vázquez Sierra, C.; Waldi, R.; Wallace, C.; Wallace, R.; Walsh, J.; Wang, J.; Ward, D. R.; Wark, H. M.; Watson, N. K.; Websdale, D.; Weiden, A.; Whitehead, M.; Wicht, J.; Wilkinson, G.; Wilkinson, M.; Williams, M.; Williams, M. P.; Williams, M.; Williams, T.; Wilson, F. F.; Wimberley, J.; Wishahi, J.; Wislicki, W.; Witek, M.; Wormser, G.; Wotton, S. A.; Wraight, K.; Wright, S.; Wyllie, K.; Xie, Y.; Xing, Z.; Xu, Z.; Yang, Z.; Yin, H.; Yu, J.; Yuan, X.; Yushchenko, O.; Zarebski, K. A.; Zavertyaev, M.; Zhang, L.; Zhang, Y.; Zhang, Y.; Zhelezov, A.; Zheng, Y.; Zhokhov, A.; Zhu, X.; Zhukov, V.; Zucchelli, S.


    The production of t t ‾, W + b b ‾ and W + c c ‾ is studied in the forward region of proton-proton collisions collected at a centre-of-mass energy of 8 TeV by the LHCb experiment, corresponding to an integrated luminosity of 1.98 ± 0.02 fb-1. The W bosons are reconstructed in the decays W → ℓν, where ℓ denotes muon or electron, while the b and c quarks are reconstructed as jets. All measured cross-sections are in agreement with next-to-leading-order Standard Model predictions.

  18. Measurement of the D{*}(+/-) meson production cross section and F-2(c(c)over-bar) at high Q(2) in ep scattering at HERA

    CERN Document Server

    Schmitt, S; Rizvi, E; Campbell, A J; Bruncko, D; Li, G; Kiesling, C; Sankey, D P C; Horisberger, R; Trinh, T N; Rostovtsev, A; Pejchal, O; Pascaud, C; Feltesse, J; Buschhorn, G; Bozovic-Jelisavcic, I; Marti, Ll; Shtarkov, L N; Pandurovic, M; Newman, P R; Staykova, Z; Povh, B; Efremenko, V; De Wolf, E A; Nowak, G; Raspiareza, A; Gabathuler, E; Kogler, R; Raicevic, N; Mudrinic, M; Polifka, R; Cvach, J; Habib, S; Morris, J V; Lendermann, V; Landon, M P J; Thompson, P D; Barrelet, E; Sauvan, E; Begzsuren, K; Zacek, J; Henderson, R C W; Sauter, M; von den Driesch, M; Schoeffel, L; Nikiforov, A; Steder, M; Mozer, M U; Naumann, Th; Cantun Avila, K B; Alexa, C; Henschel, H; Cozzika, G; Kleinwort, C; Roland, B; Pahl, P; Wegener, D; Boudry, V; Shaw-West, R N; Turnau, J; Gogitidze, N; Piec, S; Olsson, J E; Martyn, H -U; Niebuhr, C; Kostka, P; Marage, P; Zomer, F; Malinovski, E; Dainton, J B; Brinkmann, M; Fedotov, A; Greenshaw, T; Liptaj, A; Kropivnitskaya, A; Mikocki, S; Meyer, A B; Rahmat, A J; Dodonov, V; Hildebrandt, M; Tran, T H; Lopez-Fernandez, R; Glazov, A; Salek, D; Sefkow, F; Zalesak, J; Grab, C; Haidt, D; Lastovicka-Medin, G; Tseepeldorj, B; Toll, T; Van Mechelen, P; Schultz-Coulon, H -C; Goerlich, L; Bystritskaya, L; Katzy, J; Picuric, I; Ghazaryan, S; Specka, A; Laycock, P; Spaskov, V; Bizot, J C; Kluge, T; Sloan, T; Fleischer, M; Rotaru, M; Vazdik, Y; Ravdandorj, T; Baghdasaryan, A; Patel, G D; Panagoulias, I; Kutak, K; Deak, M; Felst, R; Lipka, K; Tsakov, I; Delcourt, B; Shushkevich, S; Roosen, R; Hreus, T; Lebedev, A; Tchoulakov, V; Mehta, A; Vallee, C; Andreev, V; Herbst, M; Dubak, A; Schoning, A; Zhokin, A; Stella, B; Hennekemper, E; Ferencei, J; Rusakov, S; Murin, P; Brisson, V; Osman, S; Sunar, D; Sopicki, P; Soloviev, Y; Zohrabyan, H; Smiljanic, I; List, B; Maxfield, S J; Perez, E; Milcewicz-Mika, I; List, J; Bracinik, J; Dossanov, A; Traynor, D; Volchinski, V; Elsen, E; Contreras, J G; Klein, M; Kraemer, M; Jung, A W; Jung, H; Mueller, K; Eckerlin, G; Pitzl, D; Petrukhin, A; Hiller, K H; Gayler, J; Jacquet, M; Delvax, J; Jonsson, L; Grindhammer, G; Bunyatyan, A; Falkiewicz, A; Chekelian, V; Helebrant, C; Cerny, V; Placakyte, R; Urban, K; Cerny, K; Palichik, V; Fomenko, A; Antunovic, B; Nowak, K; Pokorny, B; Kapichine, M; Kretzschmar, J; Backovic, S; Morozov, A; Glushkov, I; Loktionova, N; Thompson, G; Brandt, G; Sykora, T; Diaconu, C; Nikitin, D; Kruger, K; Wissing, Ch; Robmann, P; Vinokurova, S; Tomasz, F; Wuensch, E; Daum, K; Stoicea, G; Cholewa, A; Truoel, P; Alimujiang, K; Meyer, J; Meyer, H; Moreau, F; Krastev, K; Straumann, U; Bartel, W; Reimer, P; Zimmermann, T; Kenyon, I R; Coughlan, J A; South, D; Herrer, G; Eliseev, A; Papadopoulou, Th; Knutsson, A; Belousov, A; Makankine, A; Ozerov, D; Hoffmann, D; Aaron, F D; Grell, B R; Janssen, X; Trevino, A Vargas; Valkarova, A; Zhang, Z; Lange, W; Fischer, D -J; Egli, S; Gouzevitch, M; Levonian, S; Radescu, V; Favart, L; Lubimov, V


    The inclusive production of D{*}(+/-)(2010) mesons in deep-inelastic e(+/-)p scattering is measured in the kinematic region of photon virtuality 100 1 5 GeV The data were collected by the H1 experiment during the period from 2004 to 2007 and correspond to an integrated luminosity of 351 pb(-1) The charm contribution. F-2(c (c) over bar), to the proton structure function F-2 is determined. The measurements are compared with QCD predictions. (C) 2010 Elsevier B V All rights reserved

  19. The cause of anomaly of temperature dependence of electroresistance of the ordering nonstoichiometric FeCo compounds based on a b.c.c. lattice

    Energy Technology Data Exchange (ETDEWEB)

    Repetsky, S.P. [Taras Shevchenko Kyiv National University, 2 Acad. Glushkov Prosp., 03022 Kyiv (Ukraine); Melnyk, I.M. [Taras Shevchenko Kyiv National University, 2 Acad. Glushkov Prosp., 03022 Kyiv (Ukraine)], E-mail:; Tatarenko, V.A. [Taras Shevchenko Kyiv National University, 2 Acad. Glushkov Prosp., 03022 Kyiv (Ukraine); G.V. Kurdyumov Institute for Metal Physics, N.A.S.U., 36 Acad. Vernadsky Blvd., 03142 Kyiv (Ukraine); Len, E.G. [G.V. Kurdyumov Institute for Metal Physics, N.A.S.U., 36 Acad. Vernadsky Blvd., 03142 Kyiv (Ukraine); Vyshivanaya, I.G. [Taras Shevchenko Kyiv National University, 2 Acad. Glushkov Prosp., 03022 Kyiv (Ukraine)


    A theory of energy spectrum and electrical conductivity, which takes into account the electron scattering by the potentials of ions and fluctuations of both the spin and charge densities of electrons in disordered substitutional alloys, is developed. Calculations of temperature-concentration dependence of electrical resistance were performed for b.c.c.-Fe{sub 1-c}Co{sub c} alloys. The causes of weak temperature dependence of electrical resistance of the Fe-Co alloys are governed by the presence of a quasi-gap in the electron-energy spectrum, which appears due to strong electron correlations as well as atomic and magnetic orders.

  20. Reactions of a stable dialkylsilylene and their mechanisms

    Indian Academy of Sciences (India)

    Mitsuo Kira


    Various reactions for a stable dialkylsilylene, 2,2,5,5-tetrakis(trimethylsilyl)silacyclopentane-1,1-diyl (1), are summarized and their mechanisms are discussed. Silylene 1 isomerizes to the corresponding silaethene via the 1,2-trimethylsilyl migration. Reduction of 1 with alkali metals affords the corresponding radical anion 1.− with a relatively small 29Si hfs constant (2.99 mT) and a large g-factor (g = 2.0077) compared with those for trivalent silyl radicals. Photo-excitation of 1 generates the corresponding singlet excited state (11*) with the lifetime of 80.5 ns. The excited state reacts with C=C double bond compounds including benzene, naphthalene, and ()- and ()-2-butenes. Although the thermal reactions of 1 with haloalkanes occur via radical mechanisms, the insertion into O-H, Si-H and Si-Cl bonds proceeds concertedly via the threemembered cyclic transition states. The reaction of 1 with H2SiCl2 gives the Si-Cl insertion product exclusively, while the quantitative insertion to Si-H bond occurs when Me2SiHCl is used as a substrate. The origin of the rather unusual Si-H/Si-Cl selectivity is elucidated using DFT calculations. Silylene 1 adds to C=C, C≡C, and C=O bonds to afford the corresponding silacycles as stable compounds. The importance of the carbonyl silaylides during the reactions of silylenes with aldehydes and ketones is emphasized.

  1. Synthesis and characterization of Yb and Er based monosilicate powders and durability of plasma sprayed Yb{sub 2}SiO{sub 5} coatings on C/C-SiC composites

    Energy Technology Data Exchange (ETDEWEB)

    Khan, Zuhair S.; Zou Binglin; Huang Wenzhi; Fan Xizhi; Gu Lijian; Chen Xiaolong; Zeng Shuibing; Wang Chunjie [State Key Laboratory of Rare Earth Resources Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, Jilin (China); Cao Xueqiang, E-mail: [State Key Laboratory of Rare Earth Resources Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, Jilin (China)


    Highlights: Black-Right-Pointing-Pointer Ultra-pure rare-earth monosilicate powders based on Er and Yb have been fabricated by solid-state reaction. Black-Right-Pointing-Pointer Spray-drying treatment results in powders with free flowing characteristics and rounded surface morphologies. Black-Right-Pointing-Pointer CTEs are found to be 7.1 ppm/ Degree-Sign C for Yb{sub 2}SiO{sub 5} and 7.5 ppm/ Degree-Sign C for Er{sub 2}SiO{sub 5}. Black-Right-Pointing-Pointer Plasma spraying has been used to deposit Yb{sub 2}SiO{sub 5} coatings on C/C-SiC substrate. Black-Right-Pointing-Pointer Coatings remain strongly intact with the substrate on thermal cycling between {approx}400 Degree-Sign C and 1500 Degree-Sign C in gas burner rig experiment. - Abstract: Rare-earth silicates such as Yb{sub 2}SiO{sub 5} and Er{sub 2}SiO{sub 5} are promising environmental barrier coating materials for ceramic matrix composites. In this work, Yb{sub 2}SiO{sub 5} and Er{sub 2}SiO{sub 5} ceramic powders have been synthesized by solid-state reaction using Yb{sub 2}O{sub 3}, Er{sub 2}O{sub 3} and SiO{sub 2} as starting materials. The fabricated powders were subjected to spray drying treatment for subsequent synthesis of coatings by plasma spraying. The spray drying resulted in well-dispersed and spherical powder particles with good flowability. Analytical techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetry and differential scanning calorimetry (TGA/DSC) and dilatometry were applied to study the microstructural and thermal characteristics of the powders. Ultra-high purity monosilicate powders formed as a result of heating treatments at 1400 Degree-Sign C in a box furnace for 20 h. TG/DSC revealed the genesis temperatures of the silicate formation (low temperature polymorphs) and also showed that the solid-state reactions to form Yb and Er based monosilicates proceeded without any weight-loss in the tested temperature range. The values of coefficients of

  2. Luminescent pincer platinum(II) complexes with emission quantum yields up to almost unity: photophysics, photoreductive C-C bond formation, and materials applications. (United States)

    Chow, Pui-Keong; Cheng, Gang; Tong, Glenna So Ming; To, Wai-Pong; Kwong, Wai-Lun; Low, Kam-Hung; Kwok, Chi-Chung; Ma, Chensheng; Che, Chi-Ming


    Luminescent pincer-type Pt(II)  complexes supported by C-deprotonated π-extended tridentate RC^N^NR' ligands and pentafluorophenylacetylide ligands show emission quantum yields up to almost unity. Femtosecond time-resolved fluorescence measurements and time-dependent DFT calculations together reveal the dependence of excited-state structural distortions of [Pt(RC^N^NR')(CC-C6 F5 )] on the positional isomers of the tridentate ligand. Pt complexes [Pt(R-C^N^NR')(CC-Ar)] are efficient photocatalysts for visible-light-induced reductive CC bond formation. The [Pt(R-C^N^NR')(CC-C6 F5 )] complexes perform strongly as phosphorescent dopants for green- and red-emitting organic light-emitting diodes (OLEDs) with external quantum efficiency values over 22.1 %. These complexes are also applied in two-photon cellular imaging when incorporated into mesoporous silica nanoparticles (MSNs).

  3. Influence of relaxation of the atomic order in f.c.c.-Ni-Al alloys on X-ray diffuse scattering

    Energy Technology Data Exchange (ETDEWEB)

    Bokoch, S.M.; Kulish, M.P. [Taras Shevchenko Kyyiv National University (Ukraine); Leonov, D.S.; Kunitsky, Yu.A. [Technical Centre, N.A.S.U., Kyyiv (Ukraine); Tatarenko, V.A. [G.V. Kurdyumov Institute for Metal Physics, N.A.S.U., Kyyiv (Ukraine)


    The atomic short-range order (SRO) for the substitutional f.c.c.-Ni-9 at.% Al single-crystal solution is investigated using the X-ray diffuse-scattering method (supplemented by Monte Carlo simulation studies) and analyzing the salient features of the second-order phonon diffuse scattering of X-rays. As shown, in quenched state, the SRO corresponds to the presence in alloy of the static concentration waves with k{sub X}(001) and k(000.2) wave vectors. Initial SRO-kinetics stage is attended by the noticeable increasing of the diffuse-scattering intensities for wave vectors close to structural (Bragg) reflexes. Parameters of the time dependence of X-ray diffuse-scattering intensity for f.c.c.-Ni-9 at.% Al alloy (after quenching) at low annealing temperature (373 K) are significantly different for different wave vectors generating the ordering and/or clustering processes. (Abstract Copyright [2009], Wiley Periodicals, Inc.)

  4. A new, double-inversion mechanism of the F(-) + CH3Cl SN2 reaction in aqueous solution. (United States)

    Liu, Peng; Wang, Dunyou; Xu, Yulong


    Atomic-level, bimolecular nucleophilic substitution reaction mechanisms have been studied mostly in the gas phase, but the gas-phase results cannot be expected to reliably describe condensed-phase chemistry. As a novel, double-inversion mechanism has just been found for the F(-) + CH3Cl SN2 reaction in the gas phase [Nat. Commun., 2015, 6, 5972], here, using multi-level quantum mechanics methods combined with the molecular mechanics method, we discovered a new, double-inversion mechanism for this reaction in aqueous solution. However, the structures of the stationary points along the reaction path show significant differences from those in the gas phase due to the strong influence of solvent and solute interactions, especially due to the hydrogen bonds formed between the solute and the solvent. More importantly, the relationship between the two double-inversion transition states is not clear in the gas phase, but, here we revealed a novel intermediate complex serving as a "connecting link" between the two transition states of the abstraction-induced inversion and the Walden-inversion mechanisms. A detailed reaction path was constructed to show the atomic-level evolution of this novel double reaction mechanism in aqueous solution. The potentials of mean force were calculated and the obtained Walden-inversion barrier height agrees well with the available experimental value.

  5. Effect of short fiber content on mechanical properties of C/C-SiC composites prepared by WP-LSI%短碳纤维含量对温压-熔渗工艺制备C/C-SiC复合材料力学性能的影响

    Institute of Scientific and Technical Information of China (English)

    李金伟; 肖鹏; 李专; 曾志伟


    以短切碳纤维为增强体,采用温压-熔渗工艺(WP-LSI)制备纤维体积分数分别为20%、25%和30%的C/C-SiC复合材料,研究纤维含量对C/C-SiC复合材料力学性能的影响,并与国外同类产品进行对比。结果表明:随碳纤维含量增加,复合材料的开孔率降低,抗弯强度和抗压强度均提高,纤维体积分数为30%的复合材料密度达2.00 g/cm3,开孔率仅2.88%,其抗弯和垂直抗压强度分别为104.63 MPa和167.99 MPa,比纤维体积分数为20%的材料分别提高86.04%和44.76%,比国外同类产品分别提高2.03%和11.99%;随碳纤维含量增加,复合材料的破坏形式由假塑性破坏向脆性破坏转变。%C/C-SiC composite strengthened with short carbon fiber of volume fraction of 20%, 25% and 30%respectively were prepared by Warm Compressing-Liquid Silicon Infiltration (WC-LSI). The effect of fiber content on the mechanical properties of C/C-SiC was studied and compared with similar product on the market. The results show that, with increasing the carbon fiber content from 20% to 30%, the open porosity decreases, flexure strength and compressive strength of the composite increase. The density and open porosity of the C/C-SiC composite with carbon fiber content of 30%are 2.00 g/cm3 and 2.88%, respectively, the bending and vertical compressive strength are 104.63 MPa and 167.99 MPa, which are 86.04% and 44.76% higher than that of the C/C-SiC composite with carbon fiber of 20%, and are 2.03% and 11.99% higher than that of foreign sample. The failure process changes from pseudo plastic destruction to brittle failure with increasing carbon fiber content.

  6. Interpretation and application of reaction class transition state theory for accurate calculation of thermokinetic parameters using isodesmic reaction method. (United States)

    Wang, Bi-Yao; Li, Ze-Rong; Tan, Ning-Xin; Yao, Qian; Li, Xiang-Yuan


    We present a further interpretation of reaction class transition state theory (RC-TST) proposed by Truong et al. for the accurate calculation of rate coefficients for reactions in a class. It is found that the RC-TST can be interpreted through the isodesmic reaction method, which is usually used to calculate reaction enthalpy or enthalpy of formation for a species, and the theory can also be used for the calculation of the reaction barriers and reaction enthalpies for reactions in a class. A correction scheme based on this theory is proposed for the calculation of the reaction barriers and reaction enthalpies for reactions in a class. To validate the scheme, 16 combinations of various ab initio levels with various basis sets are used as the approximate methods and CCSD(T)/CBS method is used as the benchmarking method in this study to calculate the reaction energies and energy barriers for a representative set of five reactions from the reaction class: R(c)CH(R(b))CR(a)CH2 + OH(•) → R(c)C(•)(R(b))CR(a)CH2 + H2O (R(a), R(b), and R(c) in the reaction formula represent the alkyl or hydrogen). Then the results of the approximate methods are corrected by the theory. The maximum values of the average deviations of the energy barrier and the reaction enthalpy are 99.97 kJ/mol and 70.35 kJ/mol, respectively, before correction and are reduced to 4.02 kJ/mol and 8.19 kJ/mol, respectively, after correction, indicating that after correction the results are not sensitive to the level of the ab initio method and the size of the basis set, as they are in the case before correction. Therefore, reaction energies and energy barriers for reactions in a class can be calculated accurately at a relatively low level of ab initio method using our scheme. It is also shown that the rate coefficients for the five representative reactions calculated at the BHandHLYP/6-31G(d,p) level of theory via our scheme are very close to the values calculated at CCSD(T)/CBS level. Finally, reaction

  7. Thermal degradation reaction mechanism of xylose: A DFT study (United States)

    Huang, Jinbao; He, Chao; Wu, Longqin; Tong, Hong


    The thermal degradation reaction mechanism of xylose as hemicellulose model compound was investigated by using density functional theory methods M062X with the 6-31++G(d,p) basis set. Eight possible pyrolytic reaction pathways were proposed and the standard kinetic and thermodynamic parameters in all reaction pathways were calculated at different temperatures. In reaction pathway (1), xylose is first transformed into acyclic containing-carbonyl isomer, and then the isomer further decomposes through four possible pyrolysis pathways (1-1)-(1-4). Pathways (2) and (3) depict an immediate ring-opening process through the simultaneous breaking of C-O and C-C bonds. Pathways (4)-(7) describe the pyrolysis processes of various anhydro-xyloses through a direct ring-opening process. Pathway (8) gives the evolutionary process of pyranones. The calculation results show that reaction pathways (1), (2) and (5) are the major reaction channels and reaction pathways (3), (4), and (6)-(8) are the competitive reaction channels in pyrolysis of xylose. The major products of xylose pyrolysis are low molecular products such as 2-furaldehyde, glycolaldehyde, acetaldehyde, methylglyoxal and acetone, and the main competitive products are formaldehyde, formic acid, acetic acid, CO2, CH4, acetol, pyranone, and so on.

  8. FeF(3) catalyzed cascade C-C and C-N bond formation: synthesis of differentially substituted triheterocyclic benzothiazole functionalities under solvent-free condition. (United States)

    Atar, Amol B; Jeong, Yeon Tae


    A series of diverse polyfunctionalized triheterocyclic benzothiazoles were easily prepared in excellent yields via the Biginelli reaction of 2-aminobenzothiazole with substituted benzaldehydes and α-methylene ketones using FeF(3) as an expeditious catalyst under solvent-free conditions. The protocol provides a practical and straightforward approach toward highly functionalized triheterocyclic benzothiazole derivatives in excellent yields. The reaction was conveniently promoted by FeF(3) and the catalyst could be recovered easily after the reaction and reused without any loss of its catalytic activity. The advantageous features of this methodology are high atom economy, operational simplicity, shorter reaction time, convergence, and facile automation.

  9. Double Pion Production Reactions

    CERN Document Server

    Oset, E; Cano, F; Hernández, E; Kamalov, S S; Nacher, J C; Tejedor, J A G


    We report on reactions producing two pions induced by real and virtual photons or nucleons. The role of different resonances in these reactions is emphasized. Novel results on coherent two pion photoproduction in nuclei are also reported.

  10. Microfluidic chemical reaction circuits (United States)

    Lee, Chung-cheng; Sui, Guodong; Elizarov, Arkadij; Kolb, Hartmuth C.; Huang, Jiang; Heath, James R.; Phelps, Michael E.; Quake, Stephen R.; Tseng, Hsian-rong; Wyatt, Paul; Daridon, Antoine


    New microfluidic devices, useful for carrying out chemical reactions, are provided. The devices are adapted for on-chip solvent exchange, chemical processes requiring multiple chemical reactions, and rapid concentration of reagents.

  11. Microscale Thermite Reactions. (United States)

    Arnaiz, Francisco J.; Aguado, Rafael; Arnaiz, Susana


    Describes the adaptation of thermite (aluminum with metal oxides) reactions from whole-class demonstrations to student-run micro-reactions. Lists detailed directions and possible variations of the experiment. (WRM)

  12. A review of the irradiation evolution of dispersed oxide nanoparticles in the b.c.c. Fe-Cr system: Current understanding and future directions (United States)

    Wharry, Janelle P.; Swenson, Matthew J.; Yano, Kayla H.


    Thus far, a number of studies have investigated the irradiation evolution of oxide nanoparticles in b.c.c. Fe-Cr based oxide dispersion strengthened (ODS) alloys. But given the inconsistent experimental conditions, results have been widely variable and inconclusive. Crystal structure and chemistry changes differ from experiment to experiment, and the total nanoparticle volume fraction has been observed to both increase and decrease. Furthermore, there has not yet been a comprehensive review of the archival literature. In this paper, we summarize the existing studies on nanoparticle irradiation evolution. We note significant observations with respect to oxide nanoparticle crystallinity, composition, size, and number density. We discuss four possible contributing mechanisms for nanoparticle evolution: ballistic dissolution, Ostwald ripening, irradiation-enhanced diffusion, and homogeneous nucleation. Finally, we propose future directions to achieve a more comprehensive understanding of irradiation effects on oxide nanoparticles in ODS alloys.

  13. Chemical transport reactions

    CERN Document Server

    Schäfer, Harald


    Chemical Transport Reactions focuses on the processes and reactions involved in the transport of solid or liquid substances to form vapor phase reaction products. The publication first offers information on experimental and theoretical principles and the transport of solid substances and its special applications. Discussions focus on calculation of the transport effect of heterogeneous equilibria for a gas motion between equilibrium spaces; transport effect and the thermodynamic quantities of the transport reaction; separation and purification of substances by means of material transport; and


    Institute of Scientific and Technical Information of China (English)

    陶朝阳; 易杨华; 许强芝


    AIM To research the chemical constituents from dried roots of Uncaria yunanensis Hsia.C.C. METHODS Modern chromatography was used to isolate chemical components. Their structure were identified by spectral analysis. RESULTS Seven compounds were isolated and identified as 3β,6β,19α-trihydroxyurs-12-en-28 oic acid (I), 23-nor-24-esomethylene-3β,6β-19α-trihydroxyurs-12-en-28 oic acid (II), 3-oxo-6β,19α-dihydroxyurs-12-en-28 oic acid (III), oleanic acid (IV), 5,7,3′,4′-tetrahydroxy-flavan-3-ol (V), β-yohimbine (VI) and diangoutengjian I (VII). CONCLUSION All of the above compounds were isolated for the first time from the root of this plant. Among them, compound VII is a new one.%目的 研究滇钩藤(Uncaria yunnanensis Hsia.C.C)根的化学成分。方法 运用各种色谱技术进行分离,用IR,MS,1HNMR,13CNMR,2DNMR等光谱技术鉴定化合物。结果 得到7个化合物,分别鉴定为:3β,6β,19α-三羟基乌苏酸(I),23,-去甲基24烯-3β,6β,19α-乌苏酸(II),6β,19α-二羟基-乌苏酸-3-酮(III),齐墩果酸(IV),5,7,3′,4′-四羟基-黄烷-3-醇(V),β-育亨宾(VI)和滇钩藤碱I(VII)。结论 VII为新化合物,其余化合物均为首次从该植物中分得。

  15. Metathesis of alkanes and related reactions

    KAUST Repository

    Basset, Jean-Marie


    (Figure Presented) The transformation of alkanes remains a difficult challenge because of the relative inertness of the C-H and C-C bonds. The rewards for asserting synthetic control over unfunctionalized, saturated hydrocarbons are considerable, however, because converting short alkanes into longer chain analogues is usually a value-adding process. Alkane metathesis is a novel catalytic and direct transformation of two molecules of a given alkane into its lower and higher homologues; moreover, the process proceeds at relatively low temperature (ambient conditions or higher). It was discovered through the use of a silica-supported tantalum hydride, (=SiO)2TaH, a multifunctional catalyst with a single site of action. This reaction completes the story of the metathesis reactions discovered over the past 40 years: olefin metathesis, alkyne metathesis, and ene-yne cyclizations. In this Account, we examine the fundamental mechanistic aspects of alkane metathesis as well as the novel reactions that have been derived from its study. The silica-supported tantalum hydride catalyst was developed as the result of systematic and meticulous studies of the interaction between oxide supports and organometallic complexes, a field of study denoted surface organometallic chemistry (SOMC). A careful examination of this surface-supported tantalum hydride led to the later discovery of aluminasupported tungsten hydride, W(H)3/Al 2O3, which proved to be an even better catalyst for alkane metathesis. Supported tantalum and tungsten hydrides are highly unsaturated, electron-deficient species that are very reactive toward the C-H and C-C bonds of alkanes. They show a great versatility in various other reactions, such as cross-metathesis between methane and alkanes, cross-metathesis between toluene and ethane, or even methane nonoxidative coupling. Moreover, tungsten hydride exhibits a specific ability in the transformation of isobutane into 2,3-dimethylbutane as well as in the metathesis of

  16. Reaction systems with precipitation

    Directory of Open Access Journals (Sweden)

    Marek Rogalski


    Full Text Available This article proposes expanding Reaction Systems of Ehrenfeucht and Rozenberg by incorporating precipitation reactions into it. This improves the computing power of Reaction Systems by allowing us to implement a stack. This addition enables us to implement a Deterministic Pushdown Automaton.

  17. Unconventional exo selectivity in thermal normal-electron-demand Diels–Alder reactions (United States)

    Ho, Guo-Ming; Huang, Ci-Jhang; Li, Elise Yu-Tzu; Hsu, Sheng-Kai; Wu, Ti; Zulueta, Medel Manuel L.; Wu, Kevin Binchia; Hung, Shang-Cheng


    The Diels–Alder reaction is a useful tool for generating functionalized chiral molecules through the concerted cycloaddition of dienes and dienophiles leading to six-membered rings. Traditionally, the selective predictions of the products rely heavily on consideration of the secondary orbital interactions that stabilize the endo pathway. However, there remain some basic examples defying this notion and produce the exo-isomer as major product. Here we systematically evaluated of the structural features driving exo selectivity in thermal normal-electron-demand Diels–Alder reactions. Substitution at the Cβ position and the size and electronegativity of the electron-withdrawing group of the dienophile are contributing factors. Experimental and computational studies both point toward the steric and electrostatic forces between the substituents in both the diene and the dienophile that increase the likelihood of the exo pathway. For these substrates, the dominance of the endo pathway is reduced by transition state distortions and poor structural alignments of the reacting partners. We also noted the tilt of the dienophile with respect to the diene causing steric strain on the functionalities at the more advanced bond forming carbon-carbon position of the endo transition state. Insights into such factors may benefit synthetic planning and asserting control over this important named reaction.

  18. Synergistic chiral iminium and palladium catalysis: Highly regio- and enantioselective [3 + 2] annulation reaction of 2-vinylcyclopropanes with enals (United States)

    Zhu, Haipan; Du, Peile; Li, Jianjun; Liao, Ziyang; Liu, Guohua


    Summary A cooperative catalytic strategy of chiral iminium catalysis by regioselective activation of the C=C bond in enals and a transition metal promoting to open the 2-vinylcyclopropanes for highly regio- and enantioselective [3 + 2] cycloaddition reaction of 2-vinylcyclopropanes with α,β-unsaturated aldehydes has been developed. PMID:27559383

  19. The Application of Helicopter Flying Quality System with Tcl/Tk%直升机飞行品质评估系统的Tcl/Tk和C/C++混合编程

    Institute of Scientific and Technical Information of China (English)

    戴维康; 孙传伟; 李靖谊


    Tcl/Tk(Tool Command Language/TCLToolkit)是一种跨平台、可扩展、具有C/C++接口的图形用户界面开发语言.基于Linux,运用Tel/Tk和C/C++,结合Gnuplot共享工具库,本文开发了直升机飞行品质评估系统.本文主要阐述Tcl/Tk特点,讨论Tcl/Tk与C/C++混合编程主要问题及其问题的解决.该研究对发展Tcl/Tk和C/C++混合编程技术起积极推动作用.

  20. $X(3872)$ production from reactions involving $D$ and $D^*$ mesons

    CERN Document Server

    Torres, A Martinez; Navarra, F S; Nielsen, M; Abreu, Luciano M


    In this proceeding we show the results found for the cross sections of the processes $\\bar D D\\to\\pi X(3872)$, $\\bar D^* D\\to \\pi X(3872)$ and $\\bar D^* D^*\\to\\pi X(3872)$, information needed for calculations of the $X(3872)$ abundance in heavy ion collisions. Our formalism is based on the generation of $X(3872)$ from the interaction of the hadrons $\\bar D^0 D^{*0} - \\textrm{c.c}$, $D^- D^{*+} - \\textrm{c.c}$ and $D^-_s D^{*+}_s - \\textrm{c.c}$. The evaluation of the cross section associated with processes having $D^*$ meson(s) involves an anomalous vertex, $X\\bar D^* D^*$, which we have determined by considering triangular loops motivated by the molecular nature of $X(3872)$. We find that the contribution of this vertex is important. Encouraged by this finding we estimate the $X\\bar D^* D^*$ coupling, which turns out to be $1.95\\pm 0.22$. We then use it to obtain the cross section for the reaction $\\bar D^* D^*\\to\\pi X$ and find that the $X\\bar D^* D^*$ vertex is also relevant in this case. We also discuss t...


    Institute of Scientific and Technical Information of China (English)

    刘伟; 刘荣军; 曹英斌; 杨会永


    建立了C/C预制体孔隙率与C/SiC复合材料组成的关系模型,并通过表征不同孔隙率的C/C预制体气相硅浸渗制备的C/SiC复合材料的组成和力学性能对模型进行了验证.研究发现,实验结果与模型预测结果基本一致.随着C/C预制体孔隙率的增大,C/SiC复合材料的密度出现先上升后下降的规律,力学性能也遵从同样的规律.XRD分析和相含量测试结果均表明复合材料的相含量与模型预测结果基本一致.实验结果与模型预测结果产生偏差的主要原因是裂解碳反应不完全.%A model used to in search of the relationship between the porosity of C/C preforms and the constitute of C/SiC composites was established and validated, where the C/SiC composites was fabricated by the gaseous silicon infiltration process with the C/C preforms possessed different porosities. The results showed that the value derived from the experiment in accord with predicted ones mostly. With the increase of porosity of C/C perform, the density of C/SiC composites also increased at first and then decreased after a critical value, so are the mechanical properties and phase content which derived from XRD analysis. The main reason for the deviation between the model and experiment is the un-totally reaction of pyrolysis carbon.

  2. Direct Catalytic Asymmetric Mannich-Type Reaction of Alkylamides. (United States)

    Arteaga, Fernando Arteaga; Liu, Zijian; Brewitz, Lennart; Chen, Jianyang; Sun, Bo; Kumagai, Naoya; Shibasaki, Masakatsu


    Direct enolate formation coupled with subsequent enantioselective C-C bond formation remains a topic of intense interest in asymmetric catalysis. This methodology is achieved even with low acidic amides without an electron-withdrawing group at the α-position in the context of a Mannich-type reaction. Acetate-, propionate-, and butyrate-type 7-azaindoline amides served as enolate precursors to afford the desired Mannich adducts with high stereoselectivity, and ligand-enabled diastereo-divergency provided access to both anti/syn diastereomers. The facile transformation of the amide moiety ensures the synthetic utility of the Mannich adducts.

  3. One-Dimensional Stacking of Bifunctional Dithia- and Diselenadiazolyl Radicals : Preparation and Structural and Electronic Properties of 1,3-[(E2N2C)C6H4(CN2E2)] (E = S, Se)

    NARCIS (Netherlands)

    Andrews, M.P.; Douglass, D.C.; Fleming, R.M.; Glarum, S.H.; Haddon, R.C.; Marsh, P.; Oakley, R.T.; Palstra, T.T.M.; Schneemeyer, L.F.; Trucks, G.W.; Tycko, R.; Waszczak, J.V.; Young, K.M.; Zimmerman, N.M.; Cordes, A.W.


    The preparation and solid-state characterization of the 1,3-phenylene-bridged bis(dithiadiazolyl) and bis(diselenadiazolyl) diradicals 1,3-[(E2N2C)C6H4(CN2E2)] (E = S, Se) are reported. The isomorphous crystals of 1,3-[(E2N2C)C6H4(CN2E2)] so obtained are tetragonal, space group I41/a. Stacks of dira

  4. C&C08信令转接点接入网管系统的方法%The Method of C & C08 STPAccess Network Management System

    Institute of Scientific and Technical Information of China (English)

    柴智; 赵虎生


    介绍了 C&C08 STP接入天津本地电话网网管系统的组网方式和具体的接入方法,以及应注意的问题等。%The paper introduces the network arrangrment way and access method of C&C08 STP accessed Tianjin area telephone networks network management system and the problems for attention et al.

  5. Anomalous hydrocracking of triglycerides over CoMo-catalyst-influence of reaction intermediates

    Indian Academy of Sciences (India)

    M Anand; M G Sibi; D Verma; A K Sinha


    Reaction intermediates have been identified and followed to understand anomalous cracking of jathropha oil triglycerides in the presence of sulphided Co-Mo/Al2O3 catalyst. Undesirable C-C coupling reactions are favoured at temperatures between 320° and 340°C, giving waxy oligomerization products, whereas at temperatures above 340°C, direct hydrocracking of triglycerides to lighter and middle distillates were favoured. To minimize undesirable waxy oligomerization products, higher pressures (>80 bar) and higher H2/feed ratios (>1500) were necessary. Aldol condensation and ketonization reactions between the reaction intermediates are counter-productive as they result in waxy long chain oxygenated products which tend to accumulate on the catalyst surface, choke the reactor and cause rapid catalyst deactivation. Reaction conditions have to be optimized to minimize condensation reaction during this process.

  6. SurfKin: an ab initio kinetic code for modeling surface reactions. (United States)

    Le, Thong Nguyen-Minh; Liu, Bin; Huynh, Lam K


    In this article, we describe a C/C++ program called SurfKin (Surface Kinetics) to construct microkinetic mechanisms for modeling gas-surface reactions. Thermodynamic properties of reaction species are estimated based on density functional theory calculations and statistical mechanics. Rate constants for elementary steps (including adsorption, desorption, and chemical reactions on surfaces) are calculated using the classical collision theory and transition state theory. Methane decomposition and water-gas shift reaction on Ni(111) surface were chosen as test cases to validate the code implementations. The good agreement with literature data suggests this is a powerful tool to facilitate the analysis of complex reactions on surfaces, and thus it helps to effectively construct detailed microkinetic mechanisms for such surface reactions. SurfKin also opens a possibility for designing nanoscale model catalysts.

  7. A Highly Efficient and Inexpensive Palladium-Salen Complex for Room Temperature Suzuki-Miyaura Reaction

    Energy Technology Data Exchange (ETDEWEB)

    Dewan, Anindita [Dibrugarh Univ., Dibrugrah (India)


    We developed simple and efficient catalytic system based on Pd salen complex for Suzuki-Miyaura cross-coupling reaction using greener solvent. The same catalytic system is also effective for Suzuki Miyaura Cross-Coupling reaction of less reactive aryl chlorides with aryl boronic acids. The palladium catalysed Suzuki-Miyaura cross-coupling reaction is one of the most important strategy for the synthesis of biaryls, which are building blocks of numerous vital organic compounds used in pharmaceuticals, fine- and agro-chemical industries. The Suzuki-Miyaura reaction relies on the cross-coupling between aryl halides and easily accessible organoborons in presence of catalytic amount of palladium-based salts or complexes. Many ideal developments have been attained till now to improve the efficiency of this reaction and to minimize the issues related to environment pollution. Conventionally, the C-C bond formation reactions are performed using phosphine ligated palladium complexes, which show excellent activity in this transformation.

  8. Ab initio and density functional theory evidence on the rate-limiting step in the Morita-Baylis-Hillman reaction. (United States)

    Roy, Dipankar; Sunoj, Raghavan B


    The first ab initio and DFT studies on the mechanism of the MBH reaction show that the rate-limiting step involves an intramolecular proton transfer in the zwitterionic intermediate generated by the addition of enolate to electrophile. The activation barrier for the C-C bond-formation is found to be 20.2 kcal/mol lower than the proton-transfer step for the MBH reaction between methyl vinyl ketone and benzaldehyde catalyzed by DABCO.

  9. Projeto da reologia de concretos refratários zero-cimento no sistema Al2O3-SiC-C

    Directory of Open Access Journals (Sweden)

    Oliveira I. R. de


    Full Text Available Concretos refratários no sistema Al2O3-SiC-C vêm sendo utilizados principalmente no revestimento de canais de corrida de altos-fornos. A associação dessas matérias-primas tem elevado o desempenho dos concretos refratários frente às severas condições de trabalho, devido ao aumento da resistência ao choque térmico e ao ataque por escória e metal fundido. Apesar disso, o nível de conhecimento científico sobre a dispersão das partículas desse sistema multifásico é limitado. Neste trabalho, suspensões representativas da matriz de concretos refratários zero-cimento no sistema Al2O3-SiC-C foram preparadas para a avaliação da eficiência de aditivos na dispersão simultânea de diferentes matérias-primas, bem como para a análise do comportamento reológico da matriz em função do pH e teor de aditivo. Os ácidos poliacrílico e cítrico e um surfactante não iônico foram usados como dispersantes. Os valores de viscosidade aparente e tensão de escoamento obtidos foram usados para construir mapas de estabilidade da matriz. Medidas de pH e fluidez de concretos preparados com diferentes teores de aditivo mostraram que as condições iniciais de pH não foram correspondentes à região ótima de dispersão estabelecida pelos mapas de estabilidade. O uso de altos teores de ácido cítrico, bem como, o deslocamento do pH do concreto na direção da região ótima de dispersão foram eficientes para otimizar a sua fluidez.

  10. A comparative study of the DR reactions of c-C{sub 3}H{sup +}{sub 3} and l-C{sub 3}H{sup +}{sub 3}: Preliminary theoretical studies

    Energy Technology Data Exchange (ETDEWEB)

    Talbi, D [Universite Montpellier II - GRAAL, CNRS - UMR 5024, place Eugene Bataillon, 34095 Montpellier (France); Hickman, A P; Kashinski, D; Malenda, R F [Department of Physics, Lehigh University, 16 Memorial Dr. E, Bethlehem, PA, 18015 (United States); Redondo, P, E-mail: Dahbia.Talbi@graal.univ-montp2.f, E-mail: aph2@lehigh.ed [Departamento de Quimica Fisica, Facultad de Ciencias, Universidad de Valladolid, 47005 Valladolid (Spain)


    Preliminary calculations related to the dissociative recombination (DR) of electrons with C{sub 3}H{sup +}{sub 3} have been carried out. Both the linear and cyclic isomers of this ion exist in the interstellar medium, and accurate DR rate constants for both isomers are needed for astrophysical models. The electronic structure calculations reported here yield quasi-diabatic potential energy curves that can be used to assess the efficiency of dissociation of a CH bond. The calculations confirm a favorable position of a dissociative state for the cyclic isomer and suggest that dissociation of the linear isomer is less probable. More detailed dynamical studies are planned, and a normal mode analysis of the vibrational modes of C{sub 3}H{sup +}{sub 3} is reported as the first step in that direction.

  11. Effect of Electrical Current on Tribological Property of the Mo2C Modified C/C-Cu Composite%电流对Mo2C改性C/C-Cu复合材料载流摩擦磨损性能的影响

    Institute of Scientific and Technical Information of China (English)

    周文艳; 彭可; 冉丽萍; 葛毅成; 易茂中


    Mo2C modified C/C-Cu composites were fabricated by infiltrating Cu into Mo2C modified C/C performs.Tribological properties of the composites were tested and the effect of electrical current on tribological properties was studied.The results indicate that the friction coefficient first increased then decreased and reached the minimum value at 5 A with the electrical current increased from 0 to 15 A.Volume wear rate of C/C-Cu composite increased gradually with the increase of current.The wear loss of the counterpart was low in the range of 0~7.5 A and then it increased as current increased.Wear mechanism was mainly abrasive wear under low current.Degree of oxidative wear increased with the increase of current and obvious arc erosion appeared at a current of 15 A.%通过对炭/炭坯体Mo2C涂层改性并熔渗Cu制备了Mo2C改性C/C-Cu复合材料,测试复合材料的载流摩擦磨损性能,研究电流强度对复合材料载流摩擦磨损性能的影响.结果表明电流由0增大至15A时,摩擦系数先减小后增大,5A时达最小值;复合材料体积磨损率逐渐增大;对偶磨损量在0~7.5A范围内较低,然后随电流增大而逐渐增大.电流较低时,磨损机制以磨粒磨损为主,随电流增大氧化磨损及黏着磨损程度提高,电流高至15A时,表现出了较明显的电弧侵蚀作用.

  12. Noncanonical Reactions of Flavoenzymes

    Directory of Open Access Journals (Sweden)

    Pablo Sobrado


    Full Text Available Enzymes containing flavin cofactors are predominantly involved in redox reactions in numerous cellular processes where the protein environment modulates the chemical reactivity of the flavin to either transfer one or two electrons. Some flavoenzymes catalyze reactions with no net redox change. In these reactions, the protein environment modulates the reactivity of the flavin to perform novel chemistries. Recent mechanistic and structural data supporting novel flavin functionalities in reactions catalyzed by chorismate synthase, type II isopentenyl diphosphate isomerase, UDP-galactopyranose mutase, and alkyl-dihydroxyacetonephosphate synthase are presented in this review. In these enzymes, the flavin plays either a direct role in acid/base reactions or as a nucleophile or electrophile. In addition, the flavin cofactor is proposed to function as a “molecular scaffold” in the formation of UDP-galactofuranose and alkyl-dihydroxyacetonephosphate by forming a covalent adduct with reaction intermediates.

  13. Reaction kinetics of polybutylene terephthalate polycondensation reaction

    NARCIS (Netherlands)

    Darda, P. J.; Hogendoorn, J. A.; Versteeg, G. F.; Souren, F.


    The kinetics of the forward polycondensation reaction of polybutylene terephthalate (PBT) has been investigated using thermogravimetric analysis (TGA). PBT - prepolymer with an initial degree of polymerization of 5.5 was used as starting material. The PBT prepolymer was prepared from dimethyl tereph

  14. Metal-mullite reactions

    Energy Technology Data Exchange (ETDEWEB)

    Loehman, R.E. [Sandia National Labs., Albuquerque, NM (United States); Tomsia, A.P. [Pask Research and Engineering, Berkeley, CA (United States)


    Mullite was reacted with pure Al and with Ti or Zr dissolved in Ag-Cu eutectic alloys at 1100 C in Ar. Analysis of the Ti and Zr-containing specimens showed reaction zones with compositions of Ti{sub 50}Cu{sub 3O}O{sub 20} and ZrO{sub 2}, respectively. The Al-mullite specimen showed much more extensive penetration into the ceramic and a more diffuse reaction zone than the other two systems. Al{sub 2}O{sub 3} and Si were the main reaction products for Al-mullite reaction.

  15. Reactions at Solid Surfaces

    CERN Document Server

    Ertl, Gerhard


    Expanding on the ideas first presented in Gerhard Ertl's acclaimed Baker Lectures at Cornell University, Reactions at Solid Surfaces comprises an authoritative, self-contained, book-length introduction to surface reactions for both professional chemists and students alike. Outlining our present understanding of the fundamental processes underlying reactions at solid surfaces, the book provides the reader with a complete view of how chemistry works at surfaces, and how to understand and probe the dynamics of surface reactions. Comparing traditional surface probes with more modern ones, and brin

  16. Desosamine in multicomponent reactions

    NARCIS (Netherlands)

    Achatz, Sepp; Dömling, Alexander


    Desosamine occurring ubiquitously in natural products is introduced into isocyanide based multicomponent reaction chemistry. Corresponding products are of potential interest for the design of novel antibiotics. © 2006.

  17. Facile synthesis of a MoO2-Mo2C-C composite and its application as favorable anode material for lithium-ion batteries (United States)

    Zhu, Yanping; Wang, Shaofeng; Zhong, Yijun; Cai, Rui; Li, Li; Shao, Zongping


    A composite of MoO2-Mo2C-C is fabricated through a facile ion-exchange route for the first time as an alternative anode material for lithium-ion batteries (LIBs). A macroporous cinnamic anion-exchange resin interacts with ammonium molybdate tetrahydrate in aqueous solution, and the product is then calcined under an inert gas atmosphere. The interaction between the resin and ammonium molybdate tetrahydrate results in an atomic level dispersion of the molybdenum over the organic carbon precursor (resin), while the calcination process allows the formation of MoO2 and Mo2C as well as the pyrolysis of resin to solid carbon. According to field-emission scanning electron microscopy (SEM) and transmission electron microscopy (TEM) measurements, ultrafine MoO2 and Mo2C nanoparticles are uniformly dispersed but firmly attached within an amorphous carbon framework. When evaluated as an anode material, the as-synthesized sample exhibits superior electrochemical performance. The specific discharge capacity is as high as 1491 mA h g-1 in the first cycle and 724 mA h g-1 over 50 cycles at a current density of 0.2 A g-1. This simple, environmentally friendly, low-cost and easily scaled up method, has significant potential for mass industrial production of MoO2-based material as next-generation anode material of LIBs with wide application capability.

  18. C-C chemokine receptor 2 inhibitor ameliorates hepatic steatosis by improving ER stress and inflammation in a type 2 diabetic mouse model.

    Directory of Open Access Journals (Sweden)

    Hong-Min Kim

    Full Text Available Hepatic steatosis is the accumulation of excess fat in the liver. Recently, hepatic steatosis has become more important because it occurs in the patients with obesity, type 2 diabetes, and hyperlipidemia and is associated with endoplasmic reticulum (ER stress and insulin resistance. C-C chemokine receptor 2 (CCR2 inhibitor has been reported to improve inflammation and glucose intolerance in diabetes, but its mechanisms remained unknown in hepatic steatosis. We examined whether CCR2 inhibitor improves ER stress-induced hepatic steatosis in type 2 diabetic mice. In this study, db/db and db/m (n = 9 mice were fed CCR2 inhibitor (2 mg/kg/day for 9 weeks. In diabetic mice, CCR2 inhibitor decreased plasma and hepatic triglycerides levels and improved insulin sensitivity. Moreover, CCR2 inhibitor treatment decreased ER stress markers (e.g., BiP, ATF4, CHOP, and XBP-1 and inflammatory cytokines (e.g., TNFα, IL-6, and MCP-1 while increasing markers of mitochondrial biogenesis (e.g., PGC-1α, Tfam, and COX1 in the liver. We suggest that CCR2 inhibitor may ameliorate hepatic steatosis by reducing ER stress and inflammation in type 2 diabetes mellitus.

  19. Design and Testing of a C/C-SiC Nozzle Extension Manufactured via Filament Winding Technique and Adapted Liquid Silicon Infiltration (United States)

    Breede, F.; Koch, D.; Frieß, M.


    Nozzle extensions made of ceramic matrix composites (CMC) have the potential to improve the performance of liquid fueled rocket engines. Gas permeability and delamination have been reported to be still critical aspects in the manufacture of CMC nozzle structures. This work shows the development and manufacture of a radiation cooled C/C-SiC nozzle for a full ceramic thrust chamber. The green body was produced via advanced wet filament winding technique using multi-angle fiber architectures which were adapted to reduce the affinity of delamination during subsequent high temperature processing steps. In order to improve the final gas-tightness additional efforts were made to adjust the carbon matrix by re-infiltration for complete conversion to a dense SiC matrix with reduced amount of residual silicon after liquid silicon infiltration process. Microstructural characterization and flaw detection were performed by CT and REM analysis. Prototype nozzle extensions were manufactured and preliminary results of the structural characterization before the hot firing tests are presented.

  20. Potential Hazards Relating to Pyrolysis of c-C{sub 4}F{sub 8} in Selected Gaseous Diffusion Plant Operations

    Energy Technology Data Exchange (ETDEWEB)

    Trowbridge, L.D.


    As part of a program intended to replace the present evaporative coolant at the gaseous diffusion plants (GDPs) with a non-ozone-depleting alternate, a series of investigations of the suitability of candidate substitutes in under way. One issue concerning a primary candidate, c-C4F8, is the possibility that it might produce the highly toxic perfluoroisobutylene (PFIB) in high temperature environments. This study was commissioned to determine the likelihood and severity of decomposition under two specific high temperature thermal environments, namely the use of a flame test for the presence of coolant vapors and welding in the presence of coolant vapors. The purpose of the study was to develop and evaluate available data to provide information that will allow the technical and industrial hygiene staff at the GDPs to perform appropriate safety evaluations and to determine the need for field testing or experimental work. The scope of this study included a literature search and an evaluation of the information developed therefrom. Part of that evaluation consists of chemical kinetics modeling of coolant decomposition in the two operational environments. The general conclusions are that PFIB formation is unlikely in either situation but that it cannot be ruled out completely under extreme conditions. The presence of oxygen, moisture, and combustion products will tend to lead to formation of oxidation products (COF2, CO, CO2, and HF) rather than PFIB.

  1. Size and symmetry of the superconducting gap in the f.c.c. Cs3C60 polymorph close to the metal-Mott insulator boundary. (United States)

    Potočnik, Anton; Krajnc, Andraž; Jeglič, Peter; Takabayashi, Yasuhiro; Ganin, Alexey Y; Prassides, Kosmas; Rosseinsky, Matthew J; Arčon, Denis


    The alkali fullerides, A(3)C(60) (A = alkali metal) are molecular superconductors that undergo a transition to a magnetic Mott-insulating state at large lattice parameters. However, although the size and the symmetry of the superconducting gap, Δ, are both crucial for the understanding of the pairing mechanism, they are currently unknown for superconducting fullerides close to the correlation-driven magnetic insulator. Here we report a comprehensive nuclear magnetic resonance (NMR) study of face-centred-cubic (f.c.c.) Cs(3)C(60) polymorph, which can be tuned continuously through the bandwidth-controlled Mott insulator-metal/superconductor transition by pressure. When superconductivity emerges from the insulating state at large interfullerene separations upon compression, we observe an isotropic (s-wave) Δ with a large gap-to-superconducting transition temperature ratio, 2Δ0/k(B)T(c) = 5.3(2) [Δ0 = Δ(0 K)]. 2Δ0/k(B)T(c) decreases continuously upon pressurization until it approaches a value of ~3.5, characteristic of weak-coupling BCS theory of superconductivity despite the dome-shaped dependence of Tc on interfullerene separation. The results indicate the importance of the electronic correlations for the pairing interaction as the metal/superconductor-insulator boundary is approached.

  2. The most common mutation of KRT9, c.C487T (p.R163W), in epidermolytic palmoplantar keratoderma in two large Chinese pedigrees. (United States)

    Liu, Wen-Ting; Ke, Hai-Ping; Zhao, Yan; Chen, Xiao-Ling; Lu, Jia-Jun; Du, Zheng-Fang; Yu, Dan; Zhang, Xian-Ning


    Epidermolytic palmoplantar keratoderma (EPPK) is generally associated with dominant-negative mutations of the Keratin 9 gene (KRT9), and rarely with the Keratin 1 gene (KRT1). To date, a myriad of mutations has been reported with a high frequency of codon 163 mutations within the first exon of KRT9 in different populations. Notably, a distinct phenotypic heterogeneity, digital mutilation, was found recently in a 58-year-old female Japanese EPPK patient with p.R163W. Here, we report the most common mutation, c.C487T (p.R163W) of KRT9, in two large EPPK pedigrees from southeast China. The arginine residue in peptide position 163 remains almost constant in at least 47 intermediate filament proteins ranging from snail to human. A substitution in arginine alters both the charge and shape of the 1A rod domain and disrupts the function of the helix initiation motif of keratins, finally compromising the integrity of filaments and weakening their stability in the epidermis of palms and soles. We summarize the clinical symptoms of EPPK in Chinese and show that knuckle pads are associated with KRT9 mutations. We suggest that the frequency of p.R163W in Chinese EPPK patients (31.03%) is consistent with that in the general population (29.33%), and that codon 163 is truly a hotspot mutational site of KRT9.

  3. Changes in plasma chemokine C-C motif ligand 2 levels during treatment with eicosapentaenoic acid predict outcome in patients undergoing surgery for colorectal cancer liver metastasis (United States)

    Volpato, Milene; Perry, Sarah L; Marston, Gemma; Ingram, Nicola; Cockbain, Andrew J.; Burghel, Heather; Jake, Mann; Lowes, David; Wilson, Erica; Droop, Alastair; Randerson-Moor, Juliette; Coletta, P Louise; Hull, Mark A


    The mechanism of the anti-colorectal cancer (CRC) activity of the omega-3 fatty acid eicosapentaenoic acid (EPA) is not understood. We tested the hypothesis that EPA reduces expression of chemokine C-C motif ligand 2 (CCL2), a pro-inflammatory chemokine with known roles in metastasis. We measured CCL2 in clinical samples from a randomized trial of EPA in patients undergoing liver surgery for CRC liver metastasis (LM) and preclinical models. Genome-wide transcriptional profiling of tumors from EPA-treated patients was performed. EPA decreased CCL2 synthesis by CRC cells in a dose-dependent manner. CCL2 was localized to malignant epithelial cells in human CRCLM. EPA did not reduce CCL2 content in human or mouse tumors compare to control. However, EPA treatment was associated with decreased plasma CCL2 levels compared with controls (P=0.04). Reduction in plasma CCL2 following EPA treatment predicted improved disease-free survival (HR 0.32; P=0.003). Lack of ‘CCL2 response’ was associated with a specific CRCLM gene expression signature. In conclusion, reduction in plasma CCL2 in patients with CRCLM treated with EPA predicts better clinical outcome and a specific tumor gene expression profile. Further work is needed to validate CCL2 as a therapeutic response biomarker for omega-3 fatty acid treatment of CRC patients. PMID:27058904

  4. Ubiquitous transgenic overexpression of C-C chemokine ligand 2: a model to assess the combined effect of high energy intake and continuous low-grade inflammation. (United States)

    Rodríguez-Gallego, Esther; Riera-Borrull, Marta; Hernández-Aguilera, Anna; Mariné-Casadó, Roger; Rull, Anna; Beltrán-Debón, Raúl; Luciano-Mateo, Fedra; Menendez, Javier A; Vazquez-Martin, Alejandro; Sirvent, Juan J; Martín-Paredero, Vicente; Corbí, Angel L; Sierra-Filardi, Elena; Aragonès, Gerard; García-Heredia, Anabel; Camps, Jordi; Alonso-Villaverde, Carlos; Joven, Jorge


    Excessive energy management leads to low-grade, chronic inflammation, which is a significant factor predicting noncommunicable diseases. In turn, inflammation, oxidation, and metabolism are associated with the course of these diseases; mitochondrial dysfunction seems to be at the crossroads of mutual relationships. The migration of immune cells during inflammation is governed by the interaction between chemokines and chemokine receptors. Chemokines, especially C-C-chemokine ligand 2 (CCL2), have a variety of additional functions that are involved in the maintenance of normal metabolism. It is our hypothesis that a ubiquitous and continuous secretion of CCL2 may represent an animal model of low-grade chronic inflammation that, in the presence of an energy surplus, could help to ascertain the afore-mentioned relationships and/or to search for specific therapeutic approaches. Here, we present preliminary data on a mouse model created by using targeted gene knock-in technology to integrate an additional copy of the CCl2 gene in the Gt(ROSA)26Sor locus of the mouse genome via homologous recombination in embryonic stem cells. Short-term dietary manipulations were assessed and the findings include metabolic disturbances, premature death, and the manipulation of macrophage plasticity and autophagy. These results raise a number of mechanistic questions for future study.

  5. Ubiquitous Transgenic Overexpression of C-C Chemokine Ligand 2: A Model to Assess the Combined Effect of High Energy Intake and Continuous Low-Grade Inflammation

    Directory of Open Access Journals (Sweden)

    Esther Rodríguez-Gallego


    Full Text Available Excessive energy management leads to low-grade, chronic inflammation, which is a significant factor predicting noncommunicable diseases. In turn, inflammation, oxidation, and metabolism are associated with the course of these diseases; mitochondrial dysfunction seems to be at the crossroads of mutual relationships. The migration of immune cells during inflammation is governed by the interaction between chemokines and chemokine receptors. Chemokines, especially C-C-chemokine ligand 2 (CCL2, have a variety of additional functions that are involved in the maintenance of normal metabolism. It is our hypothesis that a ubiquitous and continuous secretion of CCL2 may represent an animal model of low-grade chronic inflammation that, in the presence of an energy surplus, could help to ascertain the afore-mentioned relationships and/or to search for specific therapeutic approaches. Here, we present preliminary data on a mouse model created by using targeted gene knock-in technology to integrate an additional copy of the CCl2 gene in the Gt(ROSA26Sor locus of the mouse genome via homologous recombination in embryonic stem cells. Short-term dietary manipulations were assessed and the findings include metabolic disturbances, premature death, and the manipulation of macrophage plasticity and autophagy. These results raise a number of mechanistic questions for future study.

  6. Effect of Al Addition on Properties of Al2O3 - SiC - C Dry Ramming Mixes for BF Trough

    Institute of Scientific and Technical Information of China (English)

    WANG Zhanmin; WANG Qiang; CAO Xiying


    Aluminium powders were introduced to Al2O3 -SiC-C dry ramming mixes in order to improve sintering properties and oxidation resistance according to their serv-ice conditions and installation methods. Properties such as bulk density, porosity, modulus of rupture, crushing strength and hot modulus of rupture as a function of alu-minium addition were investigated in the present work. The microstructure and thermodynamics for the heat trea-ted specimens were also analyzed. The results show that as aluminium addition increasing, the bulk density of the specimen treated at 220 ℃ tends to decrease and the ap-parent porosity increases, the strength of the specimens treated at 1 100 ℃ and 1 450 ℃ increases markedly, the bulk density tends to increase, apparent porosity and line-ar shrinkage decrease. The HMOR at 1 400 ℃ is en-hanced from 1.0 MPa to 3. 5 MPa with 3% aluminium. Aluminium is served as sintering agent and anti-oxidant and it will react with CO and CO2 forming Al2O3, which is helpful to enhance the strength, densify the structure and improve the overall properties.

  7. Raman spectroscopic determination of the length, strength, compressibility, Debye temperature, elasticity, and force constant of the C-C bond in graphene. (United States)

    Yang, X X; Li, J W; Zhou, Z F; Wang, Y; Yang, L W; Zheng, W T; Sun, Chang Q


    From the perspective of bond relaxation and bond vibration, we have formulated the Raman phonon relaxation of graphene, under the stimuli of the number-of-layers, the uni-axial strain, the pressure, and the temperature, in terms of the response of the length and strength of the representative bond of the entire specimen to the applied stimuli. Theoretical unification of the measurements clarifies that: (i) the opposite trends of the Raman shifts, which are due to the number-of-layers reduction, of the G-peak shift and arises from the vibration of a pair of atoms, while the D- and the 2D-peak shifts involve the z-neighbor of a specific atom; (ii) the tensile strain-induced phonon softening and phonon-band splitting arise from the asymmetric response of the C(3v) bond geometry to the C(2v) uni-axial bond elongation; (iii) the thermal softening of the phonons originates from bond expansion and weakening; and (iv) the pressure stiffening of the phonons results from bond compression and work hardening. Reproduction of the measurements has led to quantitative information about the referential frequencies from which the Raman frequencies shift as well as the length, energy, force constant, Debye temperature, compressibility and elastic modulus of the C-C bond in graphene, which is of instrumental importance in the understanding of the unusual behavior of graphene.

  8. Theoretical study on the reaction mechanism of CN radical with ketene

    Institute of Scientific and Technical Information of China (English)


    The bimolecular single collision reaction potential energy surface of CN radical with ketene (CH2CO) was investigated by means of B3LYP and QCISD(T) methods. The calculated results indicate that there are three possible channels in the reaction. The first is an attack reaction by the carbon atom of CN at the carbon atom of the methylene of CH2CO to form the intermediate NCCH2CO followed by a rupture reaction of the C-C bond combined with -CO group to the products CH2CN+CO. The second is a direct addition reaction between CN and CH2CO to form the intermediate CH2C(O)CN followed by its isomerization into NCCH2CO via a CN-shift reaction, and subsequently, NCCH2CO dissociates into CH2CN+CO through a CO-loss reaction. The last is a direct hydrogen abstraction reaction of CH2CO by CN radical. Because of the existence of a 15.44 kJ/mol reaction barrier and higher energy of reaction products, the path can be ruled out as an important channel in the reaction kinetics. The present theoretical computation results, which give an available suggestion on the reaction mechanism, are in good agreement with previous experimental studies.

  9. Friction and wear properties of C/C composites under electricity%沥青炭基C/C复合材料的载流摩擦磨损性能

    Institute of Scientific and Technical Information of China (English)

    胡聪聪; 刘洪波; 何月德; 邵南子


    通过对纯沥青炭基C/C复合材料、含炭黑沥青炭基C/C复合材料和添加氯化铁的沥青炭基C/C复合材料的载流摩擦磨损实验,发现含炭黑沥青炭基C/C复合材料的摩擦系数和磨损量最大,纯沥青炭基C/C复合材料的摩擦系数和磨损量次之,添加氯化铁的沥青炭基C/C复合材料的摩擦系数和磨损量最小,并对3种沥青炭基C/C复合材料的摩擦磨损机理进行了讨论.%The wear resistances under electricity for pitch-based C/C composites, pitch-based C/C composites containing carbon black and pitch-based C/C composites with an additive of ferric chloride have been studied. It is found that pitch-based C/C composites containing carbon black possess the largest friction coefficient and wear extent, however the pitch -based C/C composites with an additive of ferric chloride show the smallest values in the three composites. While the friction coefficient and the wear extent of the pitch-based C/C composites is in the middle. Wear mechanism of these three kinds of C/C composites is discussed.

  10. Hybrid quantum and classical methods for computing kinetic isotope effects of chemical reactions in solutions and in enzymes. (United States)

    Gao, Jiali; Major, Dan T; Fan, Yao; Lin, Yen-Lin; Ma, Shuhua; Wong, Kin-Yiu


    A method for incorporating quantum mechanics into enzyme kinetics modeling is presented. Three aspects are emphasized: 1) combined quantum mechanical and molecular mechanical methods are used to represent the potential energy surface for modeling bond forming and breaking processes, 2) instantaneous normal mode analyses are used to incorporate quantum vibrational free energies to the classical potential of mean force, and 3) multidimensional tunneling methods are used to estimate quantum effects on the reaction coordinate motion. Centroid path integral simulations are described to make quantum corrections to the classical potential of mean force. In this method, the nuclear quantum vibrational and tunneling contributions are not separable. An integrated centroid path integral-free energy perturbation and umbrella sampling (PI-FEP/UM) method along with a bisection sampling procedure was summarized, which provides an accurate, easily convergent method for computing kinetic isotope effects for chemical reactions in solution and in enzymes. In the ensemble-averaged variational transition state theory with multidimensional tunneling (EA-VTST/MT), these three aspects of quantum mechanical effects can be individually treated, providing useful insights into the mechanism of enzymatic reactions. These methods are illustrated by applications to a model process in the gas phase, the decarboxylation reaction of N-methyl picolinate in water, and the proton abstraction and reprotonation process catalyzed by alanine racemase. These examples show that the incorporation of quantum mechanical effects is essential for enzyme kinetics simulations.

  11. Selective Covalent Chemistry via Gas-Phase Ion/ion Reactions: An Exploration of the Energy Surfaces Associated with N-Hydroxysuccinimide Ester Reagents and Primary Amines and Guanidine Groups (United States)

    Bu, Jiexun; Fisher, Christine M.; Gilbert, Joshua D.; Prentice, Boone M.; McLuckey, Scott A.


    Selective covalent bond forming reactions (referred to as covalent reactions) can occur in gas-phase ion/ion reactions and take place via the formation of a long-lived chemical complex. The gas-phase ion/ion reactivity between sulfo- N-hydroxysuccinimide (sulfo-NHS) ester reagent anions and peptide cations containing a primary amine or guanidine group has been examined via DFT calculations and complex dissociation rate measurements. The results reveal insights regarding the roles of the barriers of competing processes within the complex. When the covalent reaction is exothermic, two prototypical cases, determined by the nature of the energy surface, are apparent. The product partitioning between covalent reaction and simple proton transfer upon dissociation of the long-lived complex is sensitive to activation conditions when the transition state barrier for covalent reaction is relatively high ( case 1) but is insensitive to activation conditions when the transition state barrier is relatively low ( case 2). Covalent reaction efficiencies are very high in case 2 scenarios, such as when the reactive site is a guanidine and the anion attachment site is a guanidinium ion. Covalent reaction efficiencies are variable, and generally low, in case 1 scenarios, such as when an amine is the reactive site and an ammonium ion is the site of anion attachment. A relatively long slow-heating step prior to the complex dissociation step, however, can dramatically increase covalent reaction yield in case 1 scenarios.

  12. Hydrogen evolution reaction catalyst (United States)

    Subbaraman, Ram; Stamenkovic, Vojislav; Markovic, Nenad; Tripkovic, Dusan


    Systems and methods for a hydrogen evolution reaction catalyst are provided. Electrode material includes a plurality of clusters. The electrode exhibits bifunctionality with respect to the hydrogen evolution reaction. The electrode with clusters exhibits improved performance with respect to the intrinsic material of the electrode absent the clusters.

  13. Reactions to Attitudinal Deviancy. (United States)

    Levine, John M.; Allen, Vernon L.

    This paper presents a critical review of empirical and theoretical treatments of group reaction to attitudinal deviancy. Inspired by Festinger's (1950) ideas on resolution of attitudinal discrepancies in groups, Schachter (1951) conducted an experiment that has greatly influenced subsequent research and theory concerning reaction to attitudinal…

  14. Chemical burn or reaction (United States)

    ... this page: // Chemical burn or reaction To use the sharing features on this page, please enable JavaScript. Chemicals that touch skin can lead to a reaction on the skin, throughout the body, or both. ...

  15. Chemical reaction and separation method

    NARCIS (Netherlands)

    Jansen, J.C.; Kapteijn, F.; Strous, S.A.


    The invention is directed to process for performing a chemical reaction in a reaction mixture, which reaction produces water as by-product, wherein the reaction mixture is in contact with a hydroxy sodalite membrane, through which water produced during the reaction is removed from the reaction mixtu

  16. Tabletop imaging of structural evolutions in chemical reactions

    CERN Document Server

    Ibrahim, Heide; Beaulieu, Samuel; Schmidt, Bruno E; Thiré, Nicolas; Bisson, Éric; Hebeisen, Christoph T; Wanie, Vincent; Giguére, Mathieu; Kieffer, Jean-Claude; Sanderson, Joseph; Schuurman, Michael S; Légaré, François


    The introduction of femto-chemistry has made it a primary goal to follow the nuclear and electronic evolution of a molecule in time and space as it undergoes a chemical reaction. Using Coulomb Explosion Imaging we have shot the first high-resolution molecular movie of a to and fro isomerization process in the acetylene cation. So far, this kind of phenomenon could only be observed using VUV light from a Free Electron Laser [Phys. Rev. Lett. 105, 263002 (2010)]. Here we show that 266 nm ultrashort laser pulses are capable of initiating rich dynamics through multiphoton ionization. With our generally applicable tabletop approach that can be used for other small organic molecules, we have investigated two basic chemical reactions simultaneously: proton migration and C=C bond-breaking, triggered by multiphoton ionization. The experimental results are in excellent agreement with the timescales and relaxation pathways predicted by new and definitively quantitative ab initio trajectory simulations.

  17. Organolanthanide reagents and the Mukaiyama reaction

    Energy Technology Data Exchange (ETDEWEB)

    Gong, L.


    The bis(pentamethylcyclopentadienyl) lutetium halide complex ((C/sub 5/Me/sub 5/)/sub 2/LuCl/center dot/THF) was synthesized and characterized. The crystal structure of this complex shows that the Lu is at the center of a distorted tetrahedron consisting of the centroids of two cyclopentadienyl rings, the oxygen atom of a tetrahydrofuran molecule and a chlorine atom. /sup 1/H NMR studies of toluene-d/sub 8/ solutions of (C/sub 5/Me/sub 5/LuCl(THF) + THF, (TMS/sub 2/CP)/sub 2/LuCl(THF) + THF, and (MeCp)/sub 2/LuCl(THF) + THF at various temperatures showed exchange processes between co- ordinated THF and free THF with average values of ne/ of 13.0 /+-/ 0.3 kcal/mol, 11.1 /+-/ 0.1 kcal/mol and <11 kcal/mol at 0/degree/C, respectively. It has been found that under the influence of a catalytic amount (1--5 mol %) of (TMS/sub 2/Cp)/sub 2/YbCl dimer, silyl enol ethers (R/sub 1/R/sub 2/C = C(OR/sub 3/)OSiMe/sub 3/)) react with benzaldehyde smoothly in dichloromethane at room temperature, giving >99% of the aldol silyl ether (isolated yield: 90%) within 3 h. At /minus/78/degrees/C, the reaction gives kinetically controlled diastereoselectivity, which was not observed in the TiCl/sub 4/-mediated aldol reaction. The use of organoytterbium enolates shows promise result with respect to increased stereoselectivity, and indicates the importance of the bulky ligands on the metal center. In addition, Yb(III) species can retard retroaldol reaction owing to its mild Lewis acidity. 118 refs., 14 figs., 30 tabs.

  18. Preparation of specific polyclonal antibodies to a C-C chemokine receptor, CCR1, and determination of CCR1 expression on various types of leukocytes. (United States)

    Su, S B; Mukaida, N; Wang, J; Nomura, H; Matsushima, K


    cDNA cloning has revealed the presence of at least three distinct human receptors for macrophage inflammatory protein-1alpha (MIP-1alpha) and RANTES: C-C chemokine receptor (CCR) 1, 4, and 5. To clarify the physiological role of CCR1, we prepared specific antibodies to CCR1 by immunizing rabbits with recombinant glutathione-S-transferase (GST) fused with its NH2-terminal portion. The resultant antibodies stained positively 293 cells transfected with CCR1 cDNA but neither parental cells nor cells transfected with CXCR1 [interleukin-8 (IL-8) receptor type A] cDNA, confirming its specificity. Immunofluorescence analysis revealed that peripheral blood lymphocytes and monocytes but not neutrophils express CCR1. Positive staining of transfectants, monocytes, and lymphocytes was inhibited by the GST protein fused with the NH2-terminal portion of CCR1, further indicating that this antibody recognized the NH2-terminal portion of CC CKR1. A majority of CD3+, CD4+, CD8+, or CD16+ peripheral blood lymphocytes but not CD19+ lymphocytes expressed CCR1. Among CD4+ peripheral blood lymphocytes, CD45RO+ cells expressed a larger number of CCR1 compared with CD45RO-. Moreover, CD34+ cells in human bone marrow as well as cord blood were uniformly stained with this antibody. Furthermore, the antibody inhibited calcium mobilization in CCR1 transfectants stimulated with human rMIP-1alpha, suggesting that its NH2-terminal portion is critically involved in ligand binding or signaling. Finally, the antibody partially inhibited monocyte chemotactic activities of human rMIP-1alpha, suggesting that CCR1 is a functional receptor for MIP-1alpha on human peripheral blood monocytes.

  19. Deficiency of C-C chemokine receptor 5 suppresses tumor development via inactivation of NF-κB and upregulation of IL-1Ra in melanoma model.

    Directory of Open Access Journals (Sweden)

    Ju Kyoung Song

    Full Text Available To evaluate the relevance of C-C chemokine receptor type 5 (CCR5 expression and tumor development, we compared melanoma growth in CCR5 knockout (CCR5(-/- mice and wild type (CCR5(+/+ mice. CCR5(-/- mice showed reduced tumor volume, tumor weight, and increased survival rate when compared to CCR5(+/+ mice. We investigated the activation of NF-κB since it is an implicated transcription factor in the regulation of genes involving cell growth, apoptosis, and tumor growth. Significant inhibition of DNA binding activity of NF-κB, and translocation of p50 and p65 into the nucleus through the inhibition of phosphorylation of IκB was found in the melanoma tissues of CCR5(-/- mice compared to melanoma tissues of CCR5(+/+ mice. NF-κB target apoptotic protein expression, such as cleaved caspase-3, cleaved PARP, and Bax, was elevated, whereas the survival protein expression levels, such as Bcl-2, C-IAP1, was decreased in the melanoma tissues of CCR5(-/- mice. Interestingly, we found that the level of IL-1Ra, a tumor growth suppressive cytokine, was significantly elevated in tumor tissue and spleen of CCR5(-/- mice compared to the level in CCR5(+/+ mice. Moreover, infiltration of CD8(+ cytotoxic T cell and CD57(+ natural killer cells was significantly increased in melanoma tumor and spleen tissue of CCR5(-/- mice compared to that of CCR5(+/+ mice. Therefore, these results showed that CCR5 deficiency caused apoptotic cell death of melanoma through inhibition of NF-κB and upregulation of IL-1Ra.

  20. DIFLUORPHOS and SYNPHOS in asymmetric catalysis: Synthetic applications

    Indian Academy of Sciences (India)

    Sebastien Prevost; Tahar Ayad; Jean-Pierre Genet; Phannarath Phansavath; Virginie Ratovelomanana-Vidal


    Enantiomerically pure diphosphines play an important role in various homogeneous metalcatalyzed asymmetric reactions. Over the last few years, our group has been involved in the design and synthesis of atropisomeric ligands named SYNPHOS and DIFLUORPHOS with complementary stereoelectronic properties. This paper shows the high catalytic performances of DIFLUORPHOS, SYNPHOS and SYNPHOS analogues for some C-H and C-C bond forming processes as well as for the synthesis of biorelevant targets.

  1. Degradation Behaviour of C/C Composites by Atomic Oxygen Irradiation%C/C复合材料在原子氧辐照下的结构性能演变

    Institute of Scientific and Technical Information of China (English)

    田聪; 成来飞; 栾新刚


    Erosion mechanisms of C/C composite and C/C-SiC composite (matrix modification for C/C composite using SiC) irradiated by atomic oxygen (AO) were studied by analyzing erosion morphology and mass loss rate.Thermal diffusivity coefficient,thermal expansion coefficient and flexural strength were determined before and after AO exposure test to discuss thermal physics and mechanics of AO damage.The results show that the erosion of C/C composite is the cooperation of chemical oxidation and mechanical erosion,which can be termed bombardment-induced surface chemical etching.The SiC components show good resistance to atomic oxygen erosion and hinder internal erosion.However,SiC components can also be damaged mechanically as the exposure time increasing.The mass loss rate of C/C composite is approximately proportional to the exposure time,while the mass loss rate of C/C-SiC composite is smaller than that of C/C composites and the increase of the mass loss rate slows down as the exposure time increasing.The changes of thermophysical property and mechanical property show that the overall performances of C/C and C/C-SiC have been changed to some extent after the AO exposure testing.%通过分析失重率、显微形貌变化讨论了原子氧辐照对C/C复合材料以及SiC基体改性C/C复合材料(C/C-SiC)的损伤机制;并通过热膨胀系数(CTE)、热扩散率(TD)以及弯曲强度等性能的变化,进一步讨论了原子氧辐照损伤对材料热物理及力学性能影响.结果表明,C/C复合材料受原子氧辐照损伤是物理化学综合作用,属于冲击诱发-增强表面化学刻蚀;SiC组元表现出良好的抗原子氧侵蚀性能,阻碍了原子氧向材料内部侵蚀,但是SiC组元在更长时间辐照后出现机械破损;C/C复合材料在原子氧辐照下失重率呈线性增加,而C/C-SiC复合材料失重率小于C/C复合材料且增长幅度越来越小;C/C复合材料和C/C-SiC复合材料的整体结构性能在辐照损伤后发生了一定变化.

  2. The Reaction Wheel Pendulum

    CERN Document Server

    Block, Daniel J; Spong, Mark W


    This monograph describes the Reaction Wheel Pendulum, the newest inverted-pendulum-like device for control education and research. We discuss the history and background of the reaction wheel pendulum and other similar experimental devices. We develop mathematical models of the reaction wheel pendulum in depth, including linear and nonlinear models, and models of the sensors and actuators that are used for feedback control. We treat various aspects of the control problem, from linear control of themotor, to stabilization of the pendulum about an equilibrium configuration using linear control, t

  3. Electron transfer reactions

    CERN Document Server

    Cannon, R D


    Electron Transfer Reactions deals with the mechanisms of electron transfer reactions between metal ions in solution, as well as the electron exchange between atoms or molecules in either the gaseous or solid state. The book is divided into three parts. Part 1 covers the electron transfer between atoms and molecules in the gas state. Part 2 tackles the reaction paths of oxidation states and binuclear intermediates, as well as the mechanisms of electron transfer. Part 3 discusses the theories and models of the electron transfer process; theories and experiments involving bridged electron transfe

  4. 基体炭种类对C/C复合材料电导率的影响分析%Effect of different matrix on C/C composites conductivity

    Institute of Scientific and Technical Information of China (English)

    曾光登; 刘建军; 邹武


    Pyrocarbon-matrix, resin-matrix, pitch-matrix C/C composite and pyrocarbon/pitch dual-matrix , resin/ pitch dual-matrix C/C composites were prepared respectively with needle-punched carbon felt as reinforcement. The relation was researched and compared between content of different precursor matrix antl conductivity, The. results showed that C/C composites with different precursor matrix exhibit a great difference on conductive properties, the conductivities of resin-matrix C/C composite and pitch-matrix C/C composite are three times bigger than that of pyrocarbon C/C composites. Pyrocarbon and pitch dual-matrix C/C composite conductivity accords with the simple parallel connection principle. Pitch and resin dual-matrix C/C composite conductivity is the linear function of the resin carbon mass percent.%使用炭毡为增强体分别制备了热解炭基、树脂炭基、沥青炭基和热解炭/树脂炭双基体、树脂炭/沥青炭双基体C/C复合材料,比较研究了复合材料的电导率与不同先驱体含量的关系.结果表明,不同前驱体C/C复合材料电导率有较大的差异,热解炭基C/C复合材料的电导率是沥青炭基C/C复合材料和树脂炭基C/C复合材料电导率近3倍,热解炭和沥青炭双基体C/C复合材料的电导率符合简单并联混合法则,树脂炭和沥青炭双基体C/C复合材料的电导率随树脂炭质量分数的增加而减小.

  5. Chemisorption And Precipitation Reactions (United States)

    The transport and bioavailability of chemical components within soils is, in part, controlled by partitioning between solids and solution. General terms used to describe these partitioning reactions include chemisorption and precipitation. Chemisorption is inclusive of the suit...

  6. Autocatalysis in reaction networks. (United States)

    Deshpande, Abhishek; Gopalkrishnan, Manoj


    The persistence conjecture is a long-standing open problem in chemical reaction network theory. It concerns the behavior of solutions to coupled ODE systems that arise from applying mass-action kinetics to a network of chemical reactions. The idea is that if all reactions are reversible in a weak sense, then no species can go extinct. A notion that has been found useful in thinking about persistence is that of "critical siphon." We explore the combinatorics of critical siphons, with a view toward the persistence conjecture. We introduce the notions of "drainable" and "self-replicable" (or autocatalytic) siphons. We show that: Every minimal critical siphon is either drainable or self-replicable; reaction networks without drainable siphons are persistent; and nonautocatalytic weakly reversible networks are persistent. Our results clarify that the difficulties in proving the persistence conjecture are essentially due to competition between drainable and self-replicable siphons.

  7. Translated chemical reaction networks. (United States)

    Johnston, Matthew D


    Many biochemical and industrial applications involve complicated networks of simultaneously occurring chemical reactions. Under the assumption of mass action kinetics, the dynamics of these chemical reaction networks are governed by systems of polynomial ordinary differential equations. The steady states of these mass action systems have been analyzed via a variety of techniques, including stoichiometric network analysis, deficiency theory, and algebraic techniques (e.g., Gröbner bases). In this paper, we present a novel method for characterizing the steady states of mass action systems. Our method explicitly links a network's capacity to permit a particular class of steady states, called toric steady states, to topological properties of a generalized network called a translated chemical reaction network. These networks share their reaction vectors with their source network but are permitted to have different complex stoichiometries and different network topologies. We apply the results to examples drawn from the biochemical literature.

  8. Oral Hypersensitivity Reactions (United States)

    ... food, food additives, drugs, oral hygiene products, and dental materials. Q: Are there any specific foods that are ... dental treatment trigger a hypersensitivity reaction? A: Some dental materials used by the dentist can cause a hypersensitivity ...

  9. Response reactions: equilibrium coupling. (United States)

    Hoffmann, Eufrozina A; Nagypal, Istvan


    It is pointed out and illustrated in the present paper that if a homogeneous multiple equilibrium system containing k components and q species is composed of the reactants actually taken and their reactions contain only k + 1 species, then we have a unique representation with (q - k) stoichiometrically independent reactions (SIRs). We define these as coupling reactions. All the other possible combinations with k + 1 species are the coupled reactions that are in equilibrium when the (q - k) SIRs are in equilibrium. The response of the equilibrium state for perturbation is determined by the coupling and coupled equilibria. Depending on the circumstances and the actual thermodynamic data, the effect of coupled equilibria may overtake the effect of the coupling ones, leading to phenomena that are in apparent contradiction with Le Chatelier's principle.

  10. Ofloxacin induced hypersensitivity reaction

    Directory of Open Access Journals (Sweden)

    Hari Babu Ramineni


    Full Text Available Ofloxacin is a commonly used antimicrobial agent to combat various infections. The adverse profile of quinolones includes gastrointestinal symptoms, which are the most frequent, neuropsychiatric symptoms, hematologic abnormalities are less common. We report a rare case of ofloxacin induced hypersensitivity reaction in a 57 year old female patient with complaints of rashes over the axilla, upper limb and back, abdomen, thorax associated with exfoliation of skin all over the axilla associated with severe itching. Based on history and clinical examination patient was diagnosed as ofloxacin induced hypersensitivity reaction and was successfully treated with antihistamines and corticosteroids. Pharmacovigilance should be a part of patient care in order to reduce occurrence of adverse drug reaction and also encourage practitioners in reporting so as to gather more and more data regarding adverse drug reactions. [Int J Res Med Sci 2015; 3(1.000: 349-351

  11. Allergic reactions in anaesthesia

    DEFF Research Database (Denmark)

    Krøigaard, M; Garvey, L H; Menné, T;


    BACKGROUND: The aim of this retrospective survey of possible allergic reactions during anaesthesia was to investigate whether the cause suspected by anaesthetists involved corresponded with the cause found on subsequent investigation in the Danish Anaesthesia Allergy Centre (DAAC). METHODS: Case...... notes and anaesthetic charts from 111 reactions in 107 patients investigated in the DAAC were scrutinized for either suspicions of or warnings against specific substances stated to be the cause of the supposed allergic reaction. RESULTS: In 67 cases, one or more substances were suspected. In 49...... match, the right substance being suspected, but investigations showed an additional allergen or several substances, including the right substance being suspected. CONCLUSIONS: An informed guess is not a reliable way of determining the cause of a supposed allergic reaction during anaesthesia and may put...

  12. Potential Hazards Relating to Pyrolysis of c-C{sub 4}F{sub 8}O, n-C{sub 4}F{sub 10}, and c-C{sub 4}F{sub 8} in Selected Gaseous Diffusion Plant Operations

    Energy Technology Data Exchange (ETDEWEB)

    Trowbridge, L.D.


    As part of a program intended to replace the present evaporative coolant at the gaseous diffusion plants (GDPs) with a non-ozone-depleting alternate, a series of investigations of the suitability of candidate substitutes is under way. This report summarizes studies directed at estimating the chemical and thermal stability of three candidate coolants, c-C{sub 4}F{sub 8}, n-C{sub 4}F{sub 10}, and c-C{sub 4}F{sub 8}O, in a few specific environments to be found in gaseous diffusion plant operations. One issue concerning the new coolants is the possibility that they might produce the highly toxic compound perfluoroisobutylene (PFIB) in high-temperature environments. Two specific high-temperature thermal environments are examined, namely the use of a flame test for the presence of coolant vapors and welding in the presence of coolant vapors. A second issue relates to the thermal or chemical decomposition of the coolants in the gaseous diffusion process environment. The primary purpose of the study was to develop and evaluate available data to provide information that will allow the technical and industrial hygiene staff at the GDPs to perform appropriate safety evaluations and to determine the need for field testing or experimental work. The scope of this study included a literature search and an evaluation of the information developed therefrom. Part of that evaluation consists of chemical kinetics modeling of coolant decomposition in the two operational environments. The general conclusions are that PFIB formation is unlikely in either situation but that it cannot be ruled out completely under extreme conditions. The presence of oxygen, moisture, and combustion products will tend to lead to the formation of CF{sub 4} and oxidation products (COF{sub 2}, CO, CO{sub 2}, and HF) rather than PFIB.

  13. Oxygen evolution reaction catalysis (United States)

    Haber, Joel A.; Jin, Jian; Xiang, Chengxiang; Gregoire, John M.; Jones, Ryan J.; Guevarra, Dan W.; Shinde, Aniketa A.


    An Oxygen Evolution Reaction (OER) catalyst includes a metal oxide that includes oxygen, cerium, and one or more second metals. In some instances, the cerium is 10 to 80 molar % of the metals in the metal oxide and/or the catalyst includes two or more second metals. The OER catalyst can be included in or on an electrode. The electrode can be arranged in an oxygen evolution system such that the Oxygen Evolution Reaction occurs at the electrode.

  14. Meson production in + reactions

    Indian Academy of Sciences (India)

    H Machner; M Betigeri; J Bojowald; A Budzanowski; A Chatterjee; J Ernst; L Freindl; D Frekers; W Garske; K Grewer; A Hamacher; J Ilieva; L Jarczyk; K Kilian; S Kliczewski; W Klimala; D Kolev; T Kutsarova; J Lieb; H Machner; A Magiera; H Nann; L Pentchev; H S Plendl; D Protić; B Razen; P Von Rossen; B J Roy; R Siudak; J Smyrski; R V Srikantiah; A Strzałkowski; R Tsenov; K Zwoll


    Total and differential cross sections for the reactions $p+d → 3He + 0 with = ; and + → 3H + + were measured with the GEM detector at COSY for beam momenta between threshold and the maximum of the corresponding baryon resonance. For both reactions a strong forward–backward asymmetry was found. The data were compared with model calculations. The aspect of isospin symmetry breaking is studied.

  15. Catalytic activation of carbohydrates as formaldehyde equivalents for Stetter reaction with enones. (United States)

    Zhang, Junmin; Xing, Chong; Tiwari, Bhoopendra; Chi, Yonggui Robin


    We disclose the first catalytic activation of carbohydrates as formaldehyde equivalents to generate acyl anions as one-carbon nucleophilic units for a Stetter reaction. The activation involves N-heterocyclic carbene (NHC)-catalyzed C-C bond cleavage of carbohydrates via a retro-benzoin-type process to generate the acyl anion intermediates. This Stetter reaction constitutes the first success in generating formal formaldehyde-derived acyl anions as one-carbon nucleophiles for non-self-benzoin processes. The renewable nature of carbohydrates, accessible from biomass, further highlights the practical potential of this fundamentally interesting catalytic activation.

  16. 27 CFR 28.63 - Bond, Form 2736 (5100.12). (United States)


    ... penal sum of such bond shall be not less than the tax prescribed by law on the quantity of distilled spirits or wines to be withdrawn: Provided, That the maximum penal sum of such bond shall not exceed $200,000, but in no case shall the penal sum be less than $1,000. (Sec. 201, Pub. L. 85-859, 72 Stat....

  17. 27 CFR 28.65 - Bond, Form 2738 (5110.68). (United States)


    ... Form 2738 (5110.68) as provided in § 28.51. The penal sum of the bond shall be sufficient to cover the... maximum penal sum shall not exceed $200,000, but in no case shall the penal sum be less than...

  18. 27 CFR 28.62 - Bond, Form 2735 (5100.30). (United States)


    ...), as provided in § 28.51. (b) Penal sum of bond. The penal sum of the bond shall be sufficient to cover... one time. However, the maximum penal sum of the bond shall not exceed $200,000, but in no case shall the penal sum be less than $1,000. Distilled spirits and wine withdrawn for exportation, use...

  19. 27 CFR 28.61 - Bond, Form 2734 (5100.25). (United States)


    ... filed by the exporter, as provided in § 28.51. The penal sum of the bond shall not be less than the tax prescribed by law on the quantity of spirits or wine to be withdrawn. However, the maximum penal sum of the bond shall not exceed $200,000 but in no case shall the penal sum be less than $1,000. (Sec. 201,...

  20. Proposal of a new hydrogen-bonding form to maintain curdlan triple helix. (United States)

    Miyoshi, Kentaro; Uezu, Kazuya; Sakurai, Kazuo; Shinkai, Seiji


    Curdlan and other beta-1,3-D-glucans form right-handed triple helices, and it has been believed that the intermolecular H-bond is present at the center of the helix to maintain the structure. In this H-bond model, three secondary OH groups form an inequilateral hexagonal shape perpendicular to the helix axis. This hexagonal form seems to be characteristic for beta-1,3-D-glucans and is widely accepted. We carried out MOPAC and ab initio calculations for the curdlan helix, and we propose a new intermolecular H-bonding model. In our model, the H-bonds are formed between the O2-atoms on different x-y planes along the curdlan helix, hence the H-bonds are not perpendicular to the helix axis. The new H-bonds are connected along the helix, traversing three curdlan chains to make a left-handed helix. Therefore, the H-bonding array leads to a reverse helix of the main chain. According to our MOPAC calculation, this model is more stable than the previous one. We believe that the continuous H-bonding array is stabilized by cooperative phenomena in the polymeric system.

  1. C-C扩张段材料性能设计%Material properties design of C/C nozzle divergent section

    Institute of Scientific and Technical Information of China (English)

    胡江华; 常新龙; 孟松鹤; 许承海; 朱燕伟; 陈慧


    在相同的喷管结构中,通过正交试验和喷管结构有限元热应力分析,获得径向弹性模量、母线方向(环向)弹性模量、径向热导率、母线方向(环向)热导率、径向热膨胀系数、母线方向(环向)热膨胀系数、密度和比定压热客等八因素三水平情况下的母线方向拉应力极值、环向压应力极值和层间剪切应力极值.通过极差分析,初步获得优化的材料参数设计方案,然后对试验结果进行方差分析,得出母线方向弹性模量、径向热导率和母线方向热膨胀系数这3个因素是非常显著的;结合喷管扩张段C/C复合材料的应用环境和工艺条件,得出最终的材料优化设计方案,并进行有限元热应力分析,发现应力极值都远小于现有针刺C/C复合材料的许用应力.%In a nozzle structure, through orthogonal experiment and finite element analysis, the generatrix direction maximum tension stress,hoop direction maximun eompressive stress and interlaminar maximum shear stress under three levels of radial elastic modulus, generatrix (hoop) elastic modulus, radial thermal conductivity, generatrix ( hoop ) therma! conductivity, radial thermal expansion, generatrix (hoop) thermal expansion,specific heat and density,etc. were obtained through range analysis,and optimum design scheme of parameters was preliminarily obtained. Then though variance analysis,it is found that the generatrix elastic modulus, the radial thermal conductivity and generatrix thermal expansion are three significant factors. Last, combined with C/C material application environment and technological process, the final material optimum design is presented and through finite element thermal stress analysis,it is found that the extreme stresses are far lower than allowable stresses.

  2. Bifunctional heterogeneous catalysis of silica-alumina-supported tertiary amines with controlled acid-base interactions for efficient 1,4-addition reactions. (United States)

    Motokura, Ken; Tanaka, Satoka; Tada, Mizuki; Iwasawa, Yasuhiro


    We report the first tunable bifunctional surface of silica-alumina-supported tertiary amines (SA-NEt(2)) active for catalytic 1,4-addition reactions of nitroalkanes and thiols to electron-deficient alkenes. The 1,4-addition reaction of nitroalkanes to electron-deficient alkenes is one of the most useful carbon-carbon bond-forming reactions and applicable toward a wide range of organic syntheses. The reaction between nitroethane and methyl vinyl ketone scarcely proceeded with either SA or homogeneous amines, and a mixture of SA and amines showed very low catalytic activity. In addition, undesirable side reactions occurred in the case of a strong base like sodium ethoxide employed as a catalytic reagent. Only the present SA-supported amine (SA-NEt(2)) catalyst enabled selective formation of a double-alkylated product without promotions of side reactions such as an intramolecular cyclization reaction. The heterogeneous SA-NEt(2) catalyst was easily recovered from the reaction mixture by simple filtration and reusable with retention of its catalytic activity and selectivity. Furthermore, the SA-NEt(2) catalyst system was applicable to the addition reaction of other nitroalkanes and thiols to various electron-deficient alkenes. The solid-state magic-angle spinning (MAS) NMR spectroscopic analyses, including variable-contact-time (13)C cross-polarization (CP)/MAS NMR spectroscopy, revealed that acid-base interactions between surface acid sites and immobilized amines can be controlled by pretreatment of SA at different temperatures. The catalytic activities for these addition reactions were strongly affected by the surface acid-base interactions.

  3. Le répertoire fran\\c{c}ais sur la scéne du Théatre de Boheme du Sud (1945 - 2003)


    DOSKOČILOVÁ, Kateřina


    As a lead-up this dissertation briefly describes the history of the Southbohemian Theatre. The main subject of this work is the French theatre repertory in the time period between 1945 and 2003. The work is aimed to assess the repertory especially from the point of genre structure (comedy, drama, tragedy), the proportion of French, Czech and other national literature plays and last but not least it considers reactions of critics in respect to the mentioned French plays. Part of the work is al...

  4. Indole-3-carbinol and 3’, 3’-diindolylmethane modulate androgen effect up-regulation on C-C chemokine ligand 2 and monocyte attraction to prostate cancer cells (United States)

    Inflammation has a role in prostate tumorigenesis. Recruitment of inflammatory monocytes to the tumor site is mediated by C-C chemokine ligand 2 (CCL2) through binding to its receptor CCR2. We hypothesized that androgen could modulate CCL2 expression in hormone-responsive prostate cancer cells, and ...

  5. Magnetic C-C@Fe3O4 double-shelled hollow microspheres via aerosol-based Fe3O4@C-SiO2 core-shell particles. (United States)

    Zhu, Yangzhi; Li, Xiangcun; He, Gaohong; Qi, Xinhong


    Magnetic C-C@Fe3O4 hollow microspheres were prepared by using aerosol-based Fe3O4@C-SiO2 core-shell particles as templates. The magnetic double-shelled microspheres efficiently worked as carriers to load Pt nanoparticles, thus making the catalyst recyclable and reusable.

  6. Immediate reaction to clarithromycin. (United States)

    Gangemi, S; Ricciardi, L; Fedele, R; Isola, S; Purello-D'Ambrosio, F


    We present the case of bronchospastic reaction to clarithromycin had during a drug challenge test. Personal allergic history was negative for respiratory allergies and positive for adverse drug reactions to general and regional anesthesia and to ceftriaxone. After the administration of 1/4 of therapeutic dose of clarithromycin the patient showed dyspnea, cough and bronchospasm in all the lung fields. The positivity of the test was confirmed by the negativity to the administration of placebo. The quickness and the clinical characteristic of the adverse reaction suggest a pathogenic mechanism of immediate-type hypersensitivity. On reviewing the literature we have found no reports of bronchospastic reaction to clarithromycin. Macrolides are a class of antibiotics mainly used in the last years in place of beta-lactams because of a broad spectrum of action and a low allergic power. In fact, there are few reports on allergic reactions to these molecules. Clarithromycin is one of the latest macrolides, characterised by the presence of a 14-carbon-atom lactone ring as erythromycin, active on a wide spectrum of pathogens.

  7. Chemical kinetics of gas reactions

    CERN Document Server

    Kondrat'Ev, V N


    Chemical Kinetics of Gas Reactions explores the advances in gas kinetics and thermal, photochemical, electrical discharge, and radiation chemical reactions. This book is composed of 10 chapters, and begins with the presentation of general kinetic rules for simple and complex chemical reactions. The next chapters deal with the experimental methods for evaluating chemical reaction mechanisms and some theories of elementary chemical processes. These topics are followed by discussions on certain class of chemical reactions, including unimolecular, bimolecular, and termolecular reactions. The rema

  8. 1,2-Dichlorohexafluoro-Cyclobutane (1,2-c-C4F6Cl2, R-316c) a Potent Ozone Depleting Substance and Greenhouse Gas: Atmospheric Loss Processes, Lifetimes, and Ozone Depletion and Global Warming Potentials for the (E) and (Z) stereoisomers (United States)

    Papadimitriou, Vassileios C.; McGillen, Max R.; Smith, Shona C.; Jubb, Aaron M.; Portmann, Robert W.; Hall, Bradley D.; Fleming, Eric L.; Jackman, Charles H.; Burkholder, James B.


    The atmospheric processing of (E)- and (Z)-1,2-dichlorohexafluorocyclobutane (1,2-c-C4F6Cl2, R-316c) was examined in this work as the ozone depleting (ODP) and global warming (GWP) potentials of this proposed replacement compound are presently unknown. The predominant atmospheric loss processes and infrared absorption spectra of the R-316c isomers were measured to provide a basis to evaluate their atmospheric lifetimes and, thus, ODPs and GWPs. UV absorption spectra were measured between 184.95 to 230 nm at temperatures between 214 and 296 K and a parametrization for use in atmospheric modeling is presented. The Cl atom quantum yield in the 193 nm photolysis of R- 316c was measured to be 1.90 +/- 0.27. Hexafluorocyclobutene (c-C4F6) was determined to be a photolysis co-product with molar yields of 0.7 and 1.0 (+/-10%) for (E)- and (Z)-R-316c, respectively. The 296 K total rate coefficient for the O(1D) + R-316c reaction, i.e., O(1D) loss, was measured to be (1.56 +/- 0.11) × 10(exp -10)cu cm/ molecule/s and the reactive rate coefficient, i.e., R-316c loss, was measured to be (1.36 +/- 0.20) × 10(exp -10)cu cm/molecule/s corresponding to a approx. 88% reactive yield. Rate coefficient upper-limits for the OH and O3 reaction with R-316c were determined to be global annually averaged lifetimes for the (E)- and (Z)-R-316c isomers were calculated using a 2-D atmospheric model to be 74.6 +/- 3 and 114.1 +/-10 years, respectively, where the estimated uncertainties are due solely to the uncertainty in the UV absorption spectra. Stratospheric photolysis is the predominant atmospheric loss process for both isomers with the O(1D) reaction making a minor, approx. 2% for the (E) isomer and 7% for the (Z) isomer, contribution to the total atmospheric loss. Ozone depletion potentials for (E)- and (Z)-R-316c were calculated using the 2-D model to be 0.46 and 0.54, respectively. Infrared absorption spectra for (E)- and (Z)-R-316c were measured at 296 K and used to estimate their

  9. Functionalization of methyl (R)-phenylglycinate through orthopalladation: C-Hal, C-O, C-N, and C-C bond coupling. (United States)

    Nieto, Sonia; Arnau, Palmira; Serrano, Elena; Navarro, Rafael; Soler, Tatiana; Cativiela, Carlos; Urriolabeitia, Esteban P


    The ortho functionalization of methyl R-phenylglycinate has been easily achieved using the known orthopalladated complex [Pd(mu-Cl){R-C(6)H(4)(CH(CO(2)Me)NH(2))-2}](2) (1) as synthetic tool. Different functional groups have been introduced at the ortho position of the aryl ring. The reaction of (R)-1 with X(2) or PhI(OAc)(2) gives XC(6)H(4)(CH(CO(2)Me)NH(2))-2 (X = I, Br, OMe, OEt) through oxidative coupling, while the reaction with CO gives an isoindolone. (R)-1 also reacts with one, two, or three alkyne molecules to give different metal-containing or metal-free heterocycles. The resulting functionalized amino esters or heterocycles retain the chirality of (R)-1, according with the values of the optical rotation and the obtained ee values ranging from 22%-87%. The X-ray structures of six representative compounds have also been determined.

  10. Nanoparticle Reactions on Chip (United States)

    Köhler, J. M.; Kirner, Th.; Wagner, J.; Csáki, A.; Möller, R.; Fritzsche, W.

    The handling of heterogenous systems in micro reactors is difficult due to their adhesion and transport behaviour. Therefore, the formation of precipitates and gas bubbles has to be avoided in micro reaction technology, in most cases. But, micro channels and other micro reactors offer interesting possibilities for the control of reaction conditions and transport by diffusion and convection due to the laminar flow caused by small Reynolds numbers. This can be used for the preparation and modification of objects, which are much smaller than the cross section of microchannels. The formation of colloidal solutions and the change of surface states of nano particles are two important tasks for the application of chip reactors in nanoparticle technology. Some concepts for the preparation and reaction of nanoparticles in modular chip reactor arrangements will be discussed.

  11. Inflammatory reaction in chondroblastoma

    Energy Technology Data Exchange (ETDEWEB)

    Yamamura, Sigeki [Dept. of Orthopedic Surgery, Nagoya Univ. School of Medicine (Japan); Sato, Keiji [Dept. of Orthopedic Surgery, Nagoya Univ. School of Medicine (Japan); Sugiura, Hideshi [Dept. of Orthopedic Surgery, Nagoya Univ. School of Medicine (Japan); Iwata, Hisashi [Dept. of Orthopedic Surgery, Nagoya Univ. School of Medicine (Japan)


    The objective of this study was to evaluate the inflammatory reaction accompanying chondroblastoma and to define the value of the finding in clinical practice. We reviewed the clinical, radiographic, and magnetic resonance (MR) findings in six patients with histologically proven chondroblastoma. In all cases, MR imaging showered marrow and soft tissue edema. In four of six cases, periosteal reaction related to intra-osseous edema was more clearly demonstrated on MR imaging than on radiographs. Follow-up MR studies after surgery were available in three patients and all showed disappearance of inflammatory responses such as marrow and soft tissue edema, and reactive synovitis. We propose that these inflammatory reactions of chondroblastomas are inportant signs for detecting residual tumor in recurrences after surgery, as well as for making a precise diagnosis. The MR changes may also be valuable in demonstrating eradication of the tumor. (orig./MG)

  12. Adverse reactions to cosmetics

    Directory of Open Access Journals (Sweden)

    Dogra A


    Full Text Available Adverse reaction to cosmetics constitute a small but significant number of cases of contact dermatitis with varied appearances. These can present as contact allergic dermatitis, photodermatitis, contact irritant dermatitis, contact urticaria, hypopigmentation, hyperpigmentotion or depigmentation, hair and nail breakage. Fifty patients were included for the study to assess the role of commonly used cosmetics in causing adverse reactions. It was found that hair dyes, lipsticks and surprisingly shaving creams caused more reaction as compared to other cosmetics. Overall incidence of contact allergic dermatitis seen was 3.3% with patients own cosmetics. Patch testing was also done with the basic ingredients and showed positive results in few cases where casual link could be established. It is recommended that labeling of the cosmetics should be done to help the dermatologists and the patients to identify the causative allergen in cosmetic preparation.

  13. Theoretical Study of Reaction Mechanism of 1-Propenyl Radical with NO

    Institute of Scientific and Technical Information of China (English)

    Xue-li Cheng; Yan-yun Zhao; Feng Li; Ren-tao Wu


    The reaction system of 1-propenyl radical with NO is an ideal model for studying the intermolecu- lax and intramolecular reactions of complex organic free radicals containing C=C double bonds. On the basis of the full optimization of all species with the Gaussian 98 package at the B3LYP/6- 311++G** level, the reaction mechanism was elucidated extensively using the vibrational mode analy- sis. There are seven reaction pathways and five sets of small molecule end products: CH2O+CH3CN, CH2CHCN+H2O, CH3CHO+HCN, CH3CHO+HNC, and CH3CCH+HNO. The channel of C3H5·+NO→IM1→TS1→IM2→TS2→IM3→TS3→CH3CHO+HCN is thermodynamically most favorable.

  14. Single-Site Palladium(II) Catalyst for Oxidative Heck Reaction: Catalytic Performance and Kinetic Investigations

    Energy Technology Data Exchange (ETDEWEB)

    Duan, Hui; Li, Mengyang; Zhang, Guanghui; Gallagher, James R.; Huang, Zhiliang; Sun, Yu; Luo, Zhong; Chen, Hongzhong; Miller, Jeffrey T.; Zou, Ruqiang; Lei, Aiwen; Zhao, Yanli


    ABSTRACT: The development of organometallic single-site catalysts (SSCs) has inspired the designs of new heterogeneous catalysts with high efficiency. Nevertheless, the application of SSCs in certain modern organic reactions, such as C-C bond formation reactions, has still been less investigated. In this study, a single-site Pd(II) catalyst was developed, where 2,2'-bipyridine-grafted periodic mesoporous organosilica (PMO) was employed as the support of a Pd(II) complex. The overall performance of the single-site Pd(II) catalyst in the oxidative Heck reaction was then investigated. The investigation results show that the catalyst displays over 99% selectivity for the product formation with high reaction yield. Kinetic profiles further confirm its high catalytic efficiency, showing that the rate constant is nearly 40 times higher than that for the free Pd(II) salt. X-ray absorption spectroscopy reveals that the catalyst has remarkable lifetime and recyclability.

  15. Knockout reactions: experimental aspects

    Energy Technology Data Exchange (ETDEWEB)

    Cortina Gil, D. [Santiago de Compostela Univ. (Spain)


    The availability of radioactive beams has given rise to intense activity in the field of direct reactions. The removal of one(two)-nucleon (referred to as nucleon knockout in this text) from a fast exotic projectile has been extensively investigated. This lecture provides a general overview of the experimental results achieved using this technique. The sensitivity of the method to different experimental aspects is illustrated with a few examples. Special attention is given to the application of nucleon-knockout reactions as a general purpose spectroscopic tool. (author)

  16. Reaction Qualifications Revisited

    DEFF Research Database (Denmark)

    Lippert-Rasmussen, Kasper


      When, in a competitive sphere, people are selected on the basis of qualifications only, their chances of acquiring positions of advantage may seem to depend entirely upon their abilities, not discriminatory bias. However, if reaction qualifications - i.e. characteristics which contribute...... preferences, recipients should not respond to the applicant actually hired on the basis of their (the recipients') racial preferences. My account decomposes the meritocratic ideal into four separate norms, one of which applies to recipients rather than to selectors. Finally, it defends the view that reaction...


    Energy Technology Data Exchange (ETDEWEB)

    Abplanalp, Matthew J.; Borsuk, Aleca; Jones, Brant M.; Kaiser, Ralf I., E-mail: [W. M. Keck Research Laboratory in Astrochemistry, University of Hawaii at Manoa, Honolulu, Hawaii, HI, 96822 (United States)


    The formation routes of two structural isomers—propenal (C{sub 2}H{sub 3}CHO) and cyclopropanone (c-C{sub 3}H{sub 4}O)—were investigated experimentally by exposing ices of astrophysical interest to energetic electrons at 5.5 K thus mimicking the interaction of ionizing radiation with interstellar ices in cold molecular clouds. The radiation-induced processing of these ices was monitored online and in situ via Fourier Transform Infrared spectroscopy and via temperature programmed desorption exploiting highly sensitive reflectron time-of-flight mass spectrometry coupled with single photon ionization in the post irradiation phase. To selectively probe which isomer(s) is/are formed, the photoionization experiments were conducted with 10.49 and 9.60 eV photons. Our studies provided compelling evidence on the formation of both isomers—propenal (C{sub 2}H{sub 3}CHO) and cyclopropanone (c-C{sub 3}H{sub 4}O)—in ethylene (C{sub 2}H{sub 4})—carbon monoxide (CO) ices forming propenal and cyclopropanone at a ratio of (4.5 ± 0.9):1. Based on the extracted reaction pathways, the cyclopropanone molecule can be classified as a tracer of a low temperature non-equilibrium chemistry within interstellar ices involving most likely excited triplet states, whereas propenal can be formed at ultralow temperatures, but also during the annealing phase via non-equilibrium as well as thermal chemistry (radical recombination). Since propenal has been detected in the interstellar medium and our laboratory experiments demonstrate that both isomers originated from identical precursor molecules our study predicts that the hitherto elusive second isomer—cyclopropanone—should also be observable toward those astronomical sources such as Sgr B2(N) in which propenal has been detected.

  18. Unraveling high precision stereocontrol in a triple cascade organocatalytic reaction. (United States)

    Shinisha, C B; Sunoj, Raghavan B


    The mechanism and stereoselectivity in an organocatalyzed triple cascade reaction between an aldehyde, electron deficient olefin and an alpha,beta-unsaturated aldehyde are investigated for the first time using density functional theory. The factors responsible for high levels of observed stereoselectivity (Enders et al., Nature, 2006, 441, 861) towards the generation of cyclohexene carbaldehyde with four contiguous stereocentres are unravelled. The triple cascade reaction, comprising a Michael, Michael and aldol sequence as the key elementary reactions, is studied by identifying the corresponding transition states for the stereoselective C-C bond-formation. In the first Michael addition step between the enamine (derived from the chiral catalyst and propanal) and nitrostyrene, energetically the most preferred mode of addition is found to be between the si-face of (E)-anti-enamine on the si-face of nitrostyrene. The addition of the si-face of the nitroalkane anion on the re-face of the iminium ion (formed between the enal and the catalyst) is the lowest energy pathway for the second Michael addition step. The high level of asymmetric induction is rationalized with the help of relative activation barriers associated with the competitive diastereomeric pathways. Interesting weak interactions, along with the steric effects offered by the bulky alpha-substituent on the pyrrolidine ring, are identified as critical to the stereoselectivity in this triple cascade reaction. The predicted stereoselectivities using computed energetics are found to be in perfect harmony with the experimental stereoselectivities.

  19. The Gewald multicomponent reaction

    NARCIS (Netherlands)

    Huang, Yijun; Doemling, Alexander


    The Gewald reaction of sulfur, cyanoacetic acid derivatives, and oxo-component (G-3CR) yielding highly substituted 2-aminothiophene derivatives has seen diverse applications in combinatorial and medicinal chemistry. Its products are of great use in pharmaceutical industry mainly as small molecular w

  20. Chemical Reactions at Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Michael Henderson and Nancy Ryan Gray


    Chemical reactions at surfaces underlie some of the most important processes of today, including catalysis, energy conversion, microelectronics, human health and the environment. Understanding surface chemical reactions at a fundamental level is at the core of the field of surface science. The Gordon Research Conference on Chemical Reactions at Surfaces is one of the premiere meetings in the field. The program this year will cover a broad range of topics, including heterogeneous catalysis and surface chemistry, surfaces in environmental chemistry and energy conversion, reactions at the liquid-solid and liquid-gas interface, electronic materials growth and surface modification, biological interfaces, and electrons and photons at surfaces. An exciting program is planned, with contributions from outstanding speakers and discussion leaders from the international scientific community. The conference provides a dynamic environment with ample time for discussion and interaction. Attendees are encouraged to present posters; the poster sessions are historically well attended and stimulate additional discussions. The conference provides an excellent opportunity for junior researchers (e.g. graduate students or postdocs) to present their work and interact with established leaders in the field.

  1. Reactions of Negative Ions (United States)


    2 + H2 SO 4 + HS04 (HNO 3 ) 2 + HNO 3 1.1 0.6 * defined as 1 The most important results from an atmospheric viewpoint are the reactions of H SO with NO...constant HS04 >4.5 bracketing 22 0 C1 , 1.95 * 0.25 bracketlng 32 -4 __.. . .___,_=____,,_______... . . . -- . . . . One particularly interesting aspect of

  2. Cluster knockout reactions

    Indian Academy of Sciences (India)

    Arun K Jain; B N Joshi


    Cluster knockout reactions are expected to reveal the amount of clustering (such as that of , d and even of heavier clusters such as 12C, 16O etc.) in the target nucleus. In simple terms, incident medium high-energy nuclear projectile interacts strongly with the cluster (present in the target nucleus) as if it were existing as a free entity. Theoretically, the relatively softer interactions of the two outgoing particles with the residual nucleus lead to optical distortions and are treated in terms of distorted wave (DW) formalism. The long-range projectile–cluster interaction is accounted for, in terms of the finite range (FR) direct reaction formalism, as against the more commonly adopted zero-range (ZR) distorted wave impulse approximation (DWIA) formalism. Comparison of the DWIA calculations with the observed data provide information about the momentum distribution and the clustering spectroscopic factor of the target nucleus. Interesting results and some recent advancements in the area of (, 2) reactions and heavy cluster knockout reactions are discussed. Importance of the finite-range vertex and the final-state interactions are brought out.

  3. Explaining competitive reaction effects

    NARCIS (Netherlands)

    Leeflang, P.S.H.; Wittink, D.R.


    Changes in promotional expenditure decisions for a brand, as in other marketing decisions, should be based on the expected impact on purchase and consumption behavior as well as on the likely reactions by competitors. Purchase behavior may be predicted from estimated demand functions. Competitive re

  4. Reaction Formulation: A Bibliography. (United States)

    Pedrini, D. T.; Pedrini, Bonnie C.

    Reaction formation was studied by Sigmund Freud. This defense mechanism may be related to repression, substitution, reversal, and compensation (or over-compensation). Alfred Adler considered compensation a basic process in his individual psychology. Anna Freud discussed some defense mechanisms, and Bibring, Dwyer, Huntington, and Valenstein…

  5. Reaction product imaging

    Energy Technology Data Exchange (ETDEWEB)

    Chandler, D.W. [Sandia National Laboratories, Livermore, CA (United States)


    Over the past few years the author has investigated the photochemistry of small molecules using the photofragment imaging technique. Bond energies, spectroscopy of radicals, dissociation dynamics and branching ratios are examples of information obtained by this technique. Along with extending the technique to the study of bimolecular reactions, efforts to make the technique as quantitative as possible have been the focus of the research effort. To this end, the author has measured the bond energy of the C-H bond in acetylene, branching ratios in the dissociation of HI, the energetics of CH{sub 3}Br, CD{sub 3}Br, C{sub 2}H{sub 5}Br and C{sub 2}H{sub 5}OBr dissociation, and the alignment of the CD{sub 3} fragment from CD{sub 3}I photolysis. In an effort to extend the technique to bimolecular reactions the author has studied the reaction of H with HI and the isotopic exchange reaction between H and D{sub 2}.

  6. Enantioselective Vinylogous Organocascade Reactions. (United States)

    Hepburn, Hamish B; Dell'Amico, Luca; Melchiorre, Paolo


    Cascade reactions are powerful tools for rapidly assembling complex molecular architectures from readily available starting materials in a single synthetic operation. Their marriage with asymmetric organocatalysis has led to the development of novel techniques, which are now recognized as reliable strategies for the one-pot enantioselective synthesis of stereochemically dense molecules. In recent years, even more complex synthetic challenges have been addressed by applying the principle of vinylogy to the realm of organocascade catalysis. The key to the success of vinylogous organocascade reactions is the unique ability of the chiral organocatalyst to transfer reactivity to a distal position without losing control on the stereo-determining events. This approach has greatly expanded the synthetic horizons of the field by providing the possibility of forging multiple stereocenters in remote positions from the catalyst's point of action with high selectivity, while simultaneously constructing multiple new bonds. This article critically describes the developments achieved in the field of enantioselective vinylogous organocascade reactions, charting the ideas, the conceptual advances, and the milestone reactions that have been essential for reaching highly practical levels of synthetic efficiency.


    Directory of Open Access Journals (Sweden)



    Full Text Available OBJECTIVES: Physical exercise provides multiple benefits to an individual. It is known that exercising regularly can prevent coronary heart disease, hypertension and obesity and improve flexibility. The effect of exercise on visual reaction time needs to be studied, a s the existing data on the benefit of aerobic exercise on psychomotor functions is insufficient. MATERIALS AND METHODS: Online Visual reaction time is measured before and after exercise. Subjects were instructed to run on the spot with a springy step in ex aggerated motion for 50 to 60 counts at 2 counts per second, maintaining a constant rhythm. RESULTS: We observed that reaction time was significantly lower after performance of exercise. Individuals reported improved mental alertness, feel good factor, bet ter mood and increase circulation. CONCLUSION: Improving reaction times in sports can help the athlete to optimize his performance in making decisions and increasing attention span for example getting off the starting blocks sooner or successfully making c ontact with the ball. In addition this study shows that use of physical exercise helps improve cognitive function. Exercise proves to be a cheap non pharmacological alternative to improve cognitive performance.

  8. 新致病基因在颅缝早闭Crouzon综合征中的初步机制研究%Fgfr2cC342Y/+ Mouse Model of Crouzon Syndrome in Craniosynostosis

    Institute of Scientific and Technical Information of China (English)

    杨娴娴; Jodie T Hatfield; Susan J Hinze; 穆雄铮; Peter J Anderson; Barry C Powell


    目的 研究Rbp4(Retinol binding protein 4)、Gpc3 (Glypican family of growth factor binding protein 3)、Clqtnf3 (Collagenous repeat-containing sequence of 26 KDa protein)等新致病基因在颅缝早闭症中的发病机制,为疾病非手术治疗奠定理论基础.方法 以Crouzon综合征Fgfr2cC342Y/+小鼠为实验模型,应用MicroCT和组织学染色,研究小鼠颅缝闭合模式;以Fgfr2cC342Y/+模型,RT-qPCR研究Rbp4、Gpc3、C1qtnf3等新致病基因的表达差异,初步探讨其在颅缝闭合过程中的调控作用;以体外培养的Fgfr2cC342Y/+小鼠颅缝细胞为模型,研究基因突变动物细胞增殖与代谢改变.结果 获得Fgfr2cC342Y/+小鼠后额缝、冠状缝、人字缝、矢状缝等颅缝闭合模式,随颅骨发育、颅缝闭合,OC (Osteocalcin)、ALP(Alkaline phosphatase)表达增加,目的基因Rbp4、Gpc3、Clqtnf3表达下降,Msx2(Muscle segment homeobox gene 2)表达增加,杂合子与野生型小鼠之间均存在显著统计学差异,与前期人颅缝组织Microarray研究结果一致.Gpc1 (Glypican family of growth factor binding protein 1)、FliⅠ(Flightless Ⅰ)在颅缝闭合中的表达较恒定,野生型与杂合子之间未见明显统计学差异.体外培养Fgfr2cC342Y/+小鼠颅缝细胞,CellTiter96 MTS和Quant-iT Picogreen dsDNA细胞增殖与代谢分析结果显示,Fgfr2功能获得性突变可促进冠状缝细胞的增殖,从而导致成骨增加,颅缝早闭.结论 Fgfr2cC342Y/+模型新致病基因表达趋势与前期人颅缝组织Microarray研究结果一致,Rbp4、Gpc3、C1qtnf3可能在颅缝早闭中具重要调控作用.%Objective To investigate a number of novel genes and their molecular mechanisms at play during the premature suture fusion using Fgfr2cC342Y/+ mouse model. Methods The pattern of cranial suture fusion in Fgfr2cC342Y/+ mice (a Cys342Tyr replacement into Fgfr2c to create a gain -of -function mutation equivalent to a mutation in human Crouzon syndromes) were analyzed using

  9. The human acrosome reaction

    Institute of Scientific and Technical Information of China (English)

    H.W.G.Baker; D.Y.Liu; C.Garrett; M.Martic


    We developed tests of sperm-oocyte interaction: sperm-zona binding, zona-induced acrosome reaction, spermzona penetration and sperm-oolemma binding, using oocytes which failed to fertilise in clinical in vitro fertilization (IVF). Although oocyte defects contribute to failure of sperm oocyte interaction, rarely are all oocytes from one woman affected. Low or zero fertilization in standard IVFwas usually caused by sperm abnormalities. Poor sperm-zona pellucida binding was frequently associated with failure of standard IVF and obvious defects of sperm motility or morphology. The size and shape of the acrosome is particularly important for sperm binding to the oocyte. The proportion of acrosome intact sperm in the insemination medium was related to the IVF rate. Inducing the acrosome reaction with a calcium ionophore reduced sperm-zona binding. Blocking acrosome dispersal with an acrosin inhibitor prevented spermzona penetration. Sperm-zona penetration was even more highly related to IVF rates than was sperm-zona binding. Some patients had low or zero fertilization rates with standard IVF but normal sperm by conventional tests and normal sperm-zona binding. Few of their sperm underwent the acrosome reaction on the surface of the zona and none penetrated the zona. In contrast, fertilization and pregnancy rates were high with intracytoplasmic sperm injection. We call thiscondition defective zona pellucida induced acrosome reaction. Discovery of the nature of the abnormalities in the signal transduction and effector pathways of the human zona pellucida induced acrosome reaction should result in simpler tests and treatments for the patients and also provide new leads for contraceptive development.

  10. Kinetics of Bio-Reactions

    DEFF Research Database (Denmark)


    his chapter predicts the specific rates of reaction by means of a mathematical expression, the kinetics of the reaction. This expression can be derived through a mechanistic interpretation of an enzymatically catalyzed reaction, but it is essentially of empirical nature for cell reactions. The mo...

  11. Inorganic Reaction Mechanisms. Part I (United States)

    Cooke, D. O.


    Provides a collection of data on the mechanistic aspects of inorganic chemical reactions. Wherever possible includes procedures for classroom demonstration or student project work. The material covered includes gas phase reactions, reactions in solution, mechanisms of electron transfer, the reaction between iron III and iodine, and hydrolysis. (GS)

  12. Understanding the domino reaction between 3-chloroindoles and methyl coumalate yielding carbazoles. A DFT study. (United States)

    Domingo, Luis R; Sáez, José A; Emamian, Saeed R


    The molecular mechanism of the reaction between N-methyl-3-chloroindole and methyl coumalate yielding carbazole has been studied using DFT methods at the MPWB1K/6-311G(d,p) level in toluene. This reaction is a domino process that comprises three consecutive reactions: (i) a polar Diels-Alder (P-DA) reaction between indole and methyl coumalate yielding two stereoisomeric [2 + 4] cycloadducts (CAs); (ii) the elimination of HCl from these CAs affording two stereoisomeric intermediates; and (iii) the extrusion of CO2 in these intermediates, finally yielding the carbazole. This P-DA reaction proceeds in a completely regioselective and slightly exo selective fashion. In spite of the highly polar character of this P-DA reaction, it presents a high activation enthalpy of 21.8 kcal mol(-1) due to the loss of the aromatic character of the indole during the C-C bond formation. Thermodynamic calculations suggest that the P-DA reaction is the rate-determining step of this domino reaction; in addition, the initial HCl elimination in the formal [2 + 4] CAs is kinetically favoured over the extrusion of CO2. Although the P-DA reaction is kinetically and thermodynamically very unfavourable, the easier HCl and CO2 elimination from the [2 + 4] CAs together with the strong exergonic character of the CO2 extrusion makes the P-DA reaction irreversible. An ELF topological analysis of the bonding changes along the P-DA reaction supports a two-stage one-step mechanism. An analysis of the global DFT reactivity indices at the ground state of the reagents confirms the highly polar character of this P-DA reaction. Finally, the complete regioselectivity of the studied reactions can be explained using the Parr functions.

  13. Switching on elusive organometallic mechanisms with photoredox catalysis. (United States)

    Terrett, Jack A; Cuthbertson, James D; Shurtleff, Valerie W; MacMillan, David W C


    Transition-metal-catalysed cross-coupling reactions have become one of the most used carbon-carbon and carbon-heteroatom bond-forming reactions in chemical synthesis. Recently, nickel catalysis has been shown to participate in a wide variety of C-C bond-forming reactions, most notably Negishi, Suzuki-Miyaura, Stille, Kumada and Hiyama couplings. Despite the tremendous advances in C-C fragment couplings, the ability to forge C-O bonds in a general fashion via nickel catalysis has been largely unsuccessful. The challenge for nickel-mediated alcohol couplings has been the mechanistic requirement for the critical C-O bond-forming step (formally known as the reductive elimination step) to occur via a Ni(III) alkoxide intermediate. Here we demonstrate that visible-light-excited photoredox catalysts can modulate the preferred oxidation states of nickel alkoxides in an operative catalytic cycle, thereby providing transient access to Ni(III) species that readily participate in reductive elimination. Using this synergistic merger of photoredox and nickel catalysis, we have developed a highly efficient and general carbon-oxygen coupling reaction using abundant alcohols and aryl bromides. More notably, we have developed a general strategy to 'switch on' important yet elusive organometallic mechanisms via oxidation state modulations using only weak light and single-electron-transfer catalysts.

  14. Reaction chemistry of cerium

    Energy Technology Data Exchange (ETDEWEB)



    It is truly ironic that a synthetic organic chemist likely has far greater knowledge of the reaction chemistry of cerium(IV) than an inorganic colleague. Cerium(IV) reagents have long since been employed as oxidants in effecting a wide variety of organic transformations. Conversely, prior to the late 1980s, the number of well characterized cerium(IV) complexes did not extend past a handful of known species. Though in many other areas, interest in the molecular chemistry of the 4f-elements has undergone an explosive growth over the last twenty years, the chemistry of cerium(IV) has for the most part been overlooked. This report describes reactions of cerium complexes and structure.

  15. Photooxidative reactions of psoralens

    Energy Technology Data Exchange (ETDEWEB)

    Potapenko, A.Ya.; Sukhorukov, V.L. (Vtoroj Moskovskij Gosudarstvennyj Meditsinskij Inst. (USSR))


    The mechanism and biological significance of photooxidative reactions of psoralens are reviewed. Skin-photosensitizing activities of bifunctional and monofunctional psoralens are compared. Antioxidants tocopherols and butilated hydroxytoluene inhibit photochemical reactions of psoralens responsible for induction of erythema. The same antioxidants do not inhibit PUVA-therapy of psriasis. Though psoralens can generate singlet oxygen under UVA-irradiation (315 - 400 nm), nevertheless singlet oxygen does not play a significant role in 8-methoxypsoralen (8-MOP) sensitized photooxidation of tocopherol or dihydroxyphenylalanine (DOPA). SH-compounds enhance the rate of 8-MOP sensitized photooxidation of DOPA by a factor of four, simultaneously the rate of oxidation of SH-groups is enhanced many fold in the presence of DOPA. Under UVA-irradiation in organic solvents psoralens are photooxidized. Dimeric photooxidized psoralens are easily destructed in water medium, their destruction induce oxidation of unsaturated lipids and DOPA.

  16. Photochemical reaction dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Moore, B.C. [Lawrence Berkeley Laboratory, Livermore, CA (United States)


    The purpose of the program is to develop a fundamental understanding of unimolecular and bimolecular reaction dynamics with application in combustion and energy systems. The energy dependence in ketene isomerization, ketene dissociation dynamics, and carbonyl substitution on organometallic rhodium complexes in liquid xenon have been studied. Future studies concerning unimolecular processes in ketene as well as energy transfer and kinetic studies of methylene radicals are discussed.


    Institute of Scientific and Technical Information of China (English)

    段晓东; 李贵华; 代小明; 谢长清; 王峰


    Taking high-aluminous agglomerate, carbofrax, scalelike graphite as raw materials, the effect of SiC and C on thermal shock resistance, erosion resistance, mechanical strength and oxygenproof property of Al203-SiC-C brick are analysed, and unburned Al203-SiC-C brick are developed with good properties fitting for ferroalloy works' ladles.%采用高铝矾土熟料、碳化硅、鳞片石墨为原料,通过调整加入量,研究了SiC、C对Al2O3-SiC-C不烧砖的抗热震性、抗侵蚀性、机械强度及防氧化性等性能的影响,开发出了性能优良的适用于铁合金厂铁水包的Al203-SiC-C不烧砖。

  18. Converting ultrasonic induction heating deposited monetite coating to Na-doped HA coating on H 2O 2-treated C/C composites by a two-step hydrothermal method (United States)

    Xin-bo, Xiong; Jian-feng, Hung; Xie-rong, Zeng; Cen-cen, Chu


    a monetite coating on H 2O 2-treated C/C composites was prepared by ultrasonic induction heating (UIH) technology. Subsequently, this coating was subjected to an ammonia hydrothermal treatment to form a undoped hydroxyapatite (U-HA) coating. Finally, the as-prepared U-HA coating was placed in a NaOH solution and hydrothermally treated to produce the other hydroxyapatite (Na-HA) coating. The structure, morphology and chemical composition of the two HA coatings were characterized by XRD, FTIR, SEM and EDS, the adhesiveness and local mechanical properties, e.g. nanohardness and Young's modulus of the two HA coatings to C/C composites was evaluated by a scratch test and nanoindentation technique respectively. The results showed that the two HA coatings had the alike morphology and crystallization. But, compared with the U-HA coating, the Na-HA coating was doped with Na ions, and gave a Ca/P ratio close to a stoichiometric hydroxyapatite, and thus showed a higher nano-indentation value, Young's modulus, and larger bonding strength. These results verified the strengthened effect of Na ion in hydroxyapatite coating on carbon/carbon (C/C) composities.

  19. Well sealing via thermite reactions

    Energy Technology Data Exchange (ETDEWEB)

    Lowry, William Edward; Dunn, Sandra Dalvit


    A platform is formed in a well below a target plug zone by lowering a thermite reaction charge into the well and igniting it, whereby the products of the reaction are allowed to cool and expand to form a platform or support in the well. A main thermite reaction charge is placed above the platform and ignited to form a main sealing plug for the well. In some embodiments an upper plug is formed by igniting an upper thermite reaction charge above the main thermite reaction charge. The upper plug confines the products of ignition of the main thermite reaction charge.

  20. Insect bite reactions

    Directory of Open Access Journals (Sweden)

    Sanjay Singh


    Full Text Available Insects are a class of living creatures within the arthropods. Insect bite reactions are commonly seen in clinical practice. The present review touches upon the medically important insects and their places in the classification, the sparse literature on the epidemiology of insect bites in India, and different variables influencing the susceptibility of an individual to insect bites. Clinical features of mosquito bites, hypersensitivity to mosquito bites Epstein-Barr virus NK (HMB-EBV-NK disease, eruptive pseudoangiomatosis, Skeeter syndrome, papular pruritic eruption of HIV/AIDS, and clinical features produced by bed bugs, Mexican chicken bugs, assassin bugs, kissing bugs, fleas, black flies, Blandford flies, louse flies, tsetse flies, midges, and thrips are discussed. Brief account is presented of the immunogenic components of mosquito and bed bug saliva. Papular urticaria is discussed including its epidemiology, the 5 stages of skin reaction, the SCRATCH principle as an aid in diagnosis, and the recent evidence supporting participation of types I, III, and IV hypersensitivity reactions in its causation is summarized. Recent developments in the treatment of pediculosis capitis including spinosad 0.9% suspension, benzyl alcohol 5% lotion, dimethicone 4% lotion, isopropyl myristate 50% rinse, and other suffocants are discussed within the context of evidence derived from randomized controlled trials and key findings of a recent systematic review. We also touch upon a non-chemical treatment of head lice and the ineffectiveness of egg-loosening products. Knockdown resistance (kdr as the genetic mechanism making the lice nerves insensitive to permethrin is discussed along with the surprising contrary clinical evidence from Europe about efficacy of permethrin in children with head lice carrying kdr-like gene. The review also presents a brief account of insects as vectors of diseases and ends with discussion of prevention of insect bites and some

  1. Bipodal surface organometallic complexes with surface N-donor ligands and application to the catalytic cleavage of C-H and C-C bonds in n -Butane

    KAUST Repository

    Bendjeriou-Sedjerari, Anissa


    We present a new generation of "true vicinal" functions well-distributed on the inner surface of SBA15: [(Sî - Si-NH 2)(≡Si-OH)] (1) and [(≡Si-NH2)2] (2). From these amine-modified SBA15s, two new well-defined surface organometallic species [(≡Si-NH-)(≡Si-O-)]Zr(CH2tBu) 2 (3) and [(≡Si-NH-)2]Zr(CH2tBu) 2 (4) have been obtained by reaction with Zr(CH2tBu) 4. The surfaces were characterized with 2D multiple-quantum 1H-1H NMR and infrared spectroscopies. Energy-filtered transmission electron microscopy (EFTEM), mass balance, and elemental analysis unambiguously proved that Zr(CH2tBu)4 reacts with these vicinal amine-modified surfaces to give mainly bipodal bis(neopentyl)zirconium complexes (3) and (4), uniformly distributed in the channels of SBA15. (3) and (4) react with hydrogen to give the homologous hydrides (5) and (6). Hydrogenolysis of n-butane catalyzed by these hydrides was carried out at low temperature (100 C) and low pressure (1 atm). While (6) exhibits a bis(silylamido)zirconium bishydride, [(≡Si-NH-)2]Zr(H) 2 (6a) (60%), and a bis(silylamido)silyloxozirconium monohydride, [(≡Si-NH-)2(≡Si-O-)]ZrH (6b) (40%), (5) displays a new surface organometallic complex characterized by an 1H NMR signal at 14.46 ppm. The latter is assigned to a (silylimido)(silyloxo)zirconium monohydride, [(≡Si-Nî)(≡Si-O-)]ZrH (5b) (30%), coexistent with a (silylamido)(silyloxo)zirconium bishydride, [(≡Si-NH-)(≡Si-O-)] Zr(H)2 (5a) (45%), and a silylamidobis(silyloxo)zirconium monohydride, [(≡Si-NH-)(≡Si-O-)2]ZrH (5c) (25%). Surprisingly, nitrogen surface ligands possess catalytic properties already encountered with silicon oxide surfaces, but interestingly, catalyst (5) with chelating [N,O] shows better activity than (6) with chelating [N,N]. © 2013 American Chemical Society.

  2. Multispecies pair annihilation reactions. (United States)

    Deloubrière, Olivier; Hilhorst, Henk J; Täuber, Uwe C


    We consider diffusion-limited reactions A(i)+A(j)--> (12 and d> or =2, we argue that the asymptotic density decay for such mutual annihilation processes with equal rates and initial densities is the same as for single-species pair annihilation A+A-->. In d=1, however, particle segregation occurs for all q< infinity. The total density decays according to a q dependent power law, rho(t) approximately t(-alpha(q)). Within a simplified version of the model alpha(q)=(q-1)/2q can be determined exactly. Our findings are supported through Monte Carlo simulations.

  3. Low Energy Nuclear Reactions?

    CERN Document Server

    CERN. Geneva; Faccini, R.


    After an introduction to the controversial problem of Low Energy Nuclear Reactions (LENR) catalyzed by neutrons on metallic hydride surfaces we present the results of an experiment, made in collaboration with ENEA Labs in Frascati, to search neutrons from plasma discharges in electrolytic cells. The negative outcome of our experiment goes in the direction of ruling out those theoretical models expecting LENR to occur in condensed matter systems under specific conditions. Our criticism on the theoretical foundations of such models will also be presented.

  4. 天然气定向渗透制备C/C复合材料致密化研究%Directional infiltration densification of C/C composites using natural gas as carbon source

    Institute of Scientific and Technical Information of China (English)

    庞菲; 崔红; 李瑞珍; 李晋; 孙建涛; 解惠贞


    Carbon fiber integral felt and needled felt with non-woven cloth with an initial density of 0.20 g/cm3 and 0.5 g/cm3 respectively were densified by taking natural gas( NG) as main resource gas, and the penetration depth is about 60 mm. The density of needled felt with non-woven cloth reinforced Carbon/Carbon (C/C) composites could reach 1. 39 g/cm3 in 144 hours. After 504 h infiltration, integral felt reinforced C/C composites is densified to gain 1.50 g/cm3 density, while density of needled felt with non-woven cloth reinforced C/C composites is 1.71 g/cm3. The deposition rate using natural gas as precursor is about twice the rate of deposition using propylene. The density distribution of C/C composites was studied by industrial CT qualitatively. The results show that with the increase of infiltration time, the density gradient of C/C composites decreases, and the density gradient of needled felt with non-woven cloth reinforced C/C composites is almost uniform and lower than that of integral felt reinforced C/C composites. The microstructure of matrix carbon was investigated by polarized-light microscopy, indicating that pyrolytic carbon belongs to rough laminar. With the increase of heat treatment temperature, the pyrocarbon layer becomes straight and densified.%研究以天然气为主要碳源气体、渗透深度为60 mm、密度分别为0.20、0.56 g/cm3的整体毡和针刺无纬布预制体的致密化;144 h后,针刺无纬布试样的密度达到1.39 g/cm3;504 h后,整体毡试样密度为1.50 g/cm3,针刺无纬布试样密度为1.71 g/cm3,与丙烯沉积速率相比,至少高出1倍.利用工业CT对试样密度分布进行定性分析.结果表明,随着致密化周期的增加,整体毡试样和针刺无纬布试样的内外密度梯度减小;针刺无纬布的密度梯度比整体毡小,其最终密度接近均匀分布.偏光显微镜观察测试表明,两试样的热解炭结构均为粗糙层,随着高温石墨化(HTT)处理温度的升高,热

  5. Organic chemistry: Reactions triggered electrically (United States)

    Xiang, Limin; Tao, N. J.


    Single-molecule experiments have revealed that chemical reactions can be controlled using electric fields -- and that the reaction rate is sensitive to both the direction and the strength of the applied field. See Letter p.88

  6. Theoretical Studies of Reaction Surfaces (United States)


    Similar levels of agreement are being found in studies of water clusters12 , the Menshutkin reaction 13 (ion separation reaction ), a prototypical SN2 ...of both reactants and products. These analyses reveal that Bery pseudorotation occurs repeatedly during the side attack, whereas the SN2 reaction H...31 Aug 97 4. TITLE AND SUBTITLE 5. FUNDING NUMBERS AASERT93 THEORETICAL STUDIES OF REACTION SURFACES F49620-93-1-0556 3484/XS 6. AUTHOR(S) 61103D DR

  7. Primary photodissociation pathways of epichlorohydrin and analysis of the C-C bond fission channels from an O((3)P)+allyl radical intermediate. (United States)

    Fitzpatrick, Benjamin L; Alligood, Bridget W; Butler, Laurie J; Lee, Shih-Huang; Lin, Jim Jr-Min


    This study initially characterizes the primary photodissociation processes of epichlorohydrin, c-(H(2)COCH)CH(2)Cl. The three dominant photoproduct channels analyzed are c-(H(2)COCH)CH(2)+Cl, c-(H(2)COCH)+CH(2)Cl, and C(3)H(4)O+HCl. In the second channel, the c-(H(2)COCH) photofission product is a higher energy intermediate on C(2)H(3)O global potential energy surface and has a small isomerization barrier to vinoxy. The resulting highly vibrationally excited vinoxy radicals likely dissociate to give the observed signal at the mass corresponding to ketene, H(2)CCO. The final primary photodissociation pathway HCl+C(3)H(4)O evidences a recoil kinetic energy distribution similar to that of four-center HCl elimination in chlorinated alkenes, so is assigned to production of c-(H(2)COC)=CH(2); the epoxide product is formed with enough vibrational energy to isomerize to acrolein and dissociate. The paper then analyzes the dynamics of the C(3)H(5)O radical produced from C-Cl bond photofission. When the epoxide radical photoproduct undergoes facile ring opening, it is the radical intermediate formed in the O((3)P)+allyl bimolecular reaction when the O atom adds to an end C atom. We focus on the HCO+C(2)H(4) and H(2)CO+C(2)H(3) product channels from this radical intermediate in this report. Analysis of the velocity distribution of the momentum-matched signals from the HCO+C(2)H(4) products at m/e=29 and 28 shows that the dissociation of the radical intermediate imparts a high relative kinetic energy, peaking near 20 kcal/mol, between the products. Similarly, the energy imparted to relative kinetic energy in the H(2)CO+C(2)H(3) product channel of the O((3)P)+allyl radical intermediate also peaks at high-recoil kinetic energies, near 18 kcal/mol. The strongly forward-backward peaked angular distributions and the high kinetic energy release result from tangential recoil during the dissociation of highly rotationally excited nascent radicals formed photolytically in this

  8. Orbital Energy-Based Reaction Analysis of SN2 Reactions

    Directory of Open Access Journals (Sweden)

    Takao Tsuneda


    Full Text Available An orbital energy-based reaction analysis theory is presented as an extension of the orbital-based conceptual density functional theory. In the orbital energy-based theory, the orbitals contributing to reactions are interpreted to be valence orbitals giving the largest orbital energy variation from reactants to products. Reactions are taken to be electron transfer-driven when they provide small variations for the gaps between the contributing occupied and unoccupied orbital energies on the intrinsic reaction coordinates in the initial processes. The orbital energy-based theory is then applied to the calculations of several S N2 reactions. Using a reaction path search method, the Cl− + CH3I → ClCH3 + I− reaction, for which another reaction path called “roundabout path” is proposed, is found to have a precursor process similar to the roundabout path just before this SN2 reaction process. The orbital energy-based theory indicates that this precursor process is obviously driven by structural change, while the successor SN2 reaction proceeds through electron transfer between the contributing orbitals. Comparing the calculated results of the SN2 reactions in gas phase and in aqueous solution shows that the contributing orbitals significantly depend on solvent effects and these orbitals can be correctly determined by this theory.

  9. Mass Transfer with Chemical Reaction. (United States)

    DeCoursey, W. J.


    Describes the organization of a graduate course dealing with mass transfer, particularly as it relates to chemical reactions. Discusses the course outline, including mathematics models of mass transfer, enhancement of mass transfer rates by homogeneous chemical reaction, and gas-liquid systems with chemical reaction. (TW)

  10. A crossed beam and ab initio investigation of the reaction of boron monoxide ((11)BO; X(2)Σ+) with acetylene (C2H2; X(1)Σ(g)+). (United States)

    Parker, Dorian S N; Zhang, Fangtong; Maksyutenko, Pavlo; Kaiser, Ralf I; Chang, Agnes H H


    The reaction dynamics of boron monoxide (BO; X(2)Σ(+)) with acetylene (C(2)H(2); X(1)Σ(g)(+)) were investigated under single collision conditions at a collision energy of 13 kJ mol(-1) employing the crossed molecular beam technique; electronic structure RRKM calculations were conducted to complement the experimental data. The reaction was found to have no entrance barrier and proceeded via indirect scattering dynamics initiated by an addition of the boron monoxide radical with its boron atom to the carbon-carbon triple bond forming the O(11)BHCCH intermediate. The latter decomposed via hydrogen atom emission to form the linear O(11)BCCH product through a tight exit transition state. The experimentally observed sideways scattering suggests that the hydrogen atom leaves perpendicularly to the rotational plane of the decomposing complex and almost parallel to the total angular momentum vector. RRKM calculations indicate that a minor micro channel could involve a hydrogen migration in the initial collision to form an O(11)BCCH(2) intermediate, which in turn can also emit atomic hydrogen. The overall reaction to form O(11)BCCH plus atomic hydrogen from the separated reactants was determined to be exoergic by 62 ± 8 kJ mol(-1). The reaction dynamics were also compared with the isoelectronic reaction of the cyano radical (CN; X(2)Σ(+)) with acetylene (C(2)H(2); X(1)Σ(g)(+)) studied earlier.

  11. Effect of surface reactions on steel, Al{sub 2}O{sub 3} and Si{sub 3}N{sub 4} counterparts on their tribological performance with polytetrafluoroethylene filled composites

    Energy Technology Data Exchange (ETDEWEB)

    Shen, J.T.; Top, M. [Materials Innovation Institute M2i, Department of Applied Physics, Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen (Netherlands); Ivashenko, O.; Rudolf, P. [Department of Surfaces and Thin Films, Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen (Netherlands); Pei, Y.T., E-mail: [Materials Innovation Institute M2i, Department of Applied Physics, Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen (Netherlands); Department of Advanced Production Engineering, Engineering and Technology Institute Groningen, University of Groningen, Nijenborgh 4, 9747 AG Groningen (Netherlands); De Hosson, J.Th.M., E-mail: [Materials Innovation Institute M2i, Department of Applied Physics, Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen (Netherlands)


    Highlights: • The influence of surface reactions with PTFE on the tribo-performance of different counterparts is revealed. • Experiments confirm that friction can be greatly reduced by two F-terminated surfaces sliding over each other. • Al−F and Fe−F chemical bonding form on the surface of alumina and steel counterpart balls during sliding against PTFE-containing composite. • No Si−F bonding formed on Si{sub 3}N{sub 4} ball under the same condition, leading to higher friction and wear. - Abstract: The influence of surface reactions on the tribo-performance of steel, Al{sub 2}O{sub 3} and Si{sub 3}N{sub 4} balls sliding against polytetrafluoroethylene/SiO{sub 2}/epoxy composites was investigated. Al{sub 2}O{sub 3} ball were found to exhibit the best tribo-performance, namely a low coefficient of friction and the lowest wear rates of both the composites and the counterpart ball, when sliding against the PTFE filled composites. The difference in the tribo-performance of the Al{sub 2}O{sub 3} ball and the Si{sub 3}N{sub 4} ball can neither be attributed to the different morphology of the worn composite surfaces nor to the amount of PTFE transferred onto the wear surfaces. Instead we found that the friction is greatly reduced in the case of the Al{sub 2}O{sub 3} ball because two fluoro-terminated surfaces are sliding over each other; in fact, the formation of Al−F bonding was confirmed by X-ray photoelectron spectroscopy.

  12. The Glaser–Hay reaction

    DEFF Research Database (Denmark)

    Vilhelmsen, Mie Højer; Jensen, Jonas; Tortzen, Christian


    . This unfavorable change in reaction profile could be avoided by adding molecular sieves to the reaction mixture, thereby removing the water that is accumulated from the air and produced in the reaction in which dioxygen acts as the oxidizing agent. Not unexpectedly, the stirring rate, and hence uptake of air (O2...... on the scope of this reaction by using both 13C NMR and UV/Vis spectroscopic methods. The former method was used to study the kinetics of the coupling of aryl-substituted alkynes as the aryl carbon resonances of the reactants and products have similar NOEs and relaxation times. The reaction was found...

  13. Nuclear reactions in astrophysics

    Energy Technology Data Exchange (ETDEWEB)

    Arnould, M.; Rayet, M. (Universite Libre de Bruxelles (BE))


    At all times and at all astrophysical scales, nuclear reactions have played and continue to play a key role. This concerns the energetics as well as the production of nuclides (nucleosynthesis). After a brief review of the observed composition of various objects in the universe, and especially of the solar system, the basic ingredients that are required in order to build up models for the chemical evolution of galaxies are sketched. Special attention is paid to the evaluation of the stellar yields through an overview of the important burning episodes and nucleosynthetic processes that can develop in non-exploding or exploding stars. Emphasis is put on the remaining astrophysical and nuclear physics uncertainties that hamper a clear understanding of the observed characteristics, and especially compositions, of a large variety of astrophysical objects.

  14. Hypersensitivity reaction with deferasirox

    Directory of Open Access Journals (Sweden)

    Atul Sharma


    Full Text Available Thalassemias comprise a group of hereditary blood disorders. Thalassemia major presents with anemia within the first 2 years of life requiring frequent blood transfusions for sustaining life. Regular blood transfusions lead to iron overload-related complications. Prognosis of thalassemia has improved because of the availability of iron-chelating agents. Oral iron chelators are the mainstay of chelation therapy. Deferasirox is a new-generation oral iron chelator for once daily usage. We herein describe a patient of beta thalassemia major who developed an allergic manifestation in the form of erythematous pruritic skin rashes to the oral iron chelator deferasirox. This is a rare adverse reaction reported with deferasirox that led to a therapeutic dilemma in this particular case.

  15. Hypersensitivity reaction with deferasirox. (United States)

    Sharma, Atul; Arora, Ekta; Singh, Harmanjit


    Thalassemias comprise a group of hereditary blood disorders. Thalassemia major presents with anemia within the first 2 years of life requiring frequent blood transfusions for sustaining life. Regular blood transfusions lead to iron overload-related complications. Prognosis of thalassemia has improved because of the availability of iron-chelating agents. Oral iron chelators are the mainstay of chelation therapy. Deferasirox is a new-generation oral iron chelator for once daily usage. We herein describe a patient of beta thalassemia major who developed an allergic manifestation in the form of erythematous pruritic skin rashes to the oral iron chelator deferasirox. This is a rare adverse reaction reported with deferasirox that led to a therapeutic dilemma in this particular case.

  16. Eikonal reaction theory

    CERN Document Server

    Yahiro, Masanobu; Minomo, Kosho


    We present an accurate method of treating the one-neutron removal reaction at intermediate incident energies induced by both nuclear and Coulomb interactions. In the method, the nuclear and Coulomb breakup processes are consistently treated by the method of continuum discretized coupled channels without making the adiabatic approximation to the Coulomb interaction, so that the removal cross section calculated never diverges. This method is applied to recently measured one-neutron removal cross section for $^{31}$Ne+$^{12}$C scattering at 230 MeV/nucleon and $^{31}$Ne+$^{208}$Pb scattering at 234 MeV/nucleon. The spectroscopic factor and the asymptotic normalization coefficient of the last neutron in $^{31}$Ne are evaluated.

  17. Nuclear reactions an introduction

    CERN Document Server

    Paetz gen. Schieck, Hans


    Nuclei and nuclear reactions offer a unique setting for investigating three (and in some cases even all four) of the fundamental forces in nature. Nuclei have been shown – mainly by performing scattering experiments with electrons, muons, and neutrinos – to be extended objects with complex internal structures: constituent quarks; gluons, whose exchange binds the quarks together; sea-quarks, the ubiquitous virtual quark-antiquark pairs and, last but not least, clouds of virtual mesons, surrounding an inner nuclear region, their exchange being the source of the nucleon-nucleon interaction.   The interplay between the (mostly attractive) hadronic nucleon-nucleon interaction and the repulsive Coulomb force is responsible for the existence of nuclei; their degree of stability, expressed in the details and limits of the chart of nuclides; their rich structure and the variety of their interactions. Despite the impressive successes of the classical nuclear models and of ab-initio approaches, there is clearly no ...

  18. Growth of fluorocarbon macromolecules in the gas phase: IV. Li{sup +}-attachment mass spectrometric investigation of high-mass neutral radicals in the downstream region of Ar/c-C{sub 4}F{sub 8} plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Okumura, Hiroshi; Furuya, Kenji; Harata, Akira, E-mail: [Department of Molecular and Material Sciences, Kyushu University, Kasuga, Fukuoka 816-8580 (Japan)


    Mass analysis has been conducted on neutral species in the downstream region of Ar/c-C{sub 4}F{sub 8} plasmas by Li{sup +}-attachment mass spectrometry. Various peaks appeared in the mass spectrum observed in the case of 29% c-C{sub 4}F{sub 8}, and many of them have unambiguously been assigned to the Li{sup +} adducts of neutral radicals with odd-numbered fluorine atoms from 2n + 1 to 2n - 5, where n means the number of carbon atoms, as well as neutral species with even-numbered fluorine atoms from 2n + 2 to 2n - 10. In contrast, only the peaks due to C{sub n}F{sub 2n+2} (n = 1-7), C{sub n}F{sub 2n} (n = 1, 4-8), C{sub n}F{sub 2n-2} (n = 3, 5-8) and C{sub 9}F{sub 14} appeared in the case of 2.2% c-C{sub 4}F{sub 8}. These findings demonstrate that the Li{sup +}-attachment ionization is fragment-free, not only for relatively stable perfluorocarbon species but also for their neutral radicals, and therefore effective for the identification of high-mass neutral perfluorocarbon radicals. The analysis of the growth mechanisms of C{sub n}F{sub 2n+2} and C{sub n}F{sub 2n} on the basis of thermochemistry has proposed CF{sub 3}CF as an important reactant.

  19. Evidence for the existence of $u d \\bar{b} \\bar{b}$ and the non-existence of $s s \\bar{b} \\bar{b}$ and $c c \\bar{b} \\bar{b}$ tetraquarks from lattice QCD

    CERN Document Server

    Bicudo, Pedro; Peters, Antje; Wagenbach, Björn; Wagner, Marc


    We combine lattice QCD results for the potential of two static antiquarks in the presence of two quarks $q q$ of finite mass and quark model techniques to study possibly existing $q q \\bar{b} \\bar{b}$ tetraquarks. While there is strong indication for a bound four-quark state for $q q = (ud-du) / \\sqrt{2}$, i.e. isospin $I=0$, we find clear evidence against the existence of corresponding tetraquarks with $q q \\in \\{ uu , (ud+du) / \\sqrt{2} , dd \\}$, i.e. isospin $I=1$, $q q = s s$ and $q q = c c$.

  20. 近年のハニーポット取得データ解析による C&C トラフィック分類評価



    インターネットの普及に伴い,マルウェアへの感染被害の増加が世界中で深刻な問題となっている.その中でもボットネットによる被害が顕著である.一般的なボットネットでは踏み台となるコンピュータの制御や命令を行なうためにCommand and Control(C&C)サーバを利用しており,ボットネット対策手法の1つとしてC&C サーバの検知が注目されている.従来のボットネットにおいてC&Cサーバを制御するプロトコルとしてInternet Relay Chat(IRC)を利用するものが多かった.しかし,近年ではHTTP,P2P のようなユーザへの普及率が高いプロトコルを利用したボットネットも出現しており,解析するべきトラフィック量が多くなるために検知が難しい.故にIRC プロトコルに特化したボットネット検知手法には限界がある.本研究では,近年採取されたハニーポットデータの解析結果を基に,C&C サーバの利用するプロトコルに特化しない検出手法を提案する.この手法を用いてC&C サーバの検出を行いC&C サーバとボットの通信を遮断することでボットネットからの攻撃を未然に防ぐことが我々の目的である...

  1. 機械学習を用いたセッション分類による C&C トラフィック抽出



    インターネットの普及に伴い,マルウェアへの感染被害の増加が,世界中で深刻な問題となっている.その中でも,遠隔により操作されるマルウェアを使った,ボットネットによる被害が顕著である.ボットネットが脅威となる原因の一つに,Command and Control(C&C)サーバを利用することが挙げられる.C&C サーバは踏み台となるコンピュータであるボットの制御や,命令を行なう.これにより,同時に多数のコンピュータから攻撃させることや,ハーダーの特定を困難にすることを可能にする.C&C サーバに利用されるプロトコルとして,主にInternet Relay Chat(IRC)や,HTTP などがある.従来のボットネットは,IRC サーバを利用したものが主流であったが,近年HTTP を利用したボットネットが増えており,対策をより困難にしている.本研究では,ボットネットの中でもHTTP 型ボットネットに焦点を置く.そのために,C&C サーバとボットの通信特性の調査を行い,それを基にセッション分類によるC&C トラフィック抽出を行なう.具体的には,トラフィック観測により得られたデータをセッショ...

  2. Recycling of used Al2O3-SiC-C bricks%用后Al2O3-SiC-C砖的回收再利用

    Institute of Scientific and Technical Information of China (English)

    王落霞; 沈明科; 高斌


    对铁水包和混铁车用后的Al2O3-SiC-C(简称ASC)砖进行再生处理,然后以高铝矾土熟料、电熔刚玉、叶蜡石、SiC粉和鳞片石墨为原料,分别掺加质量分数为10%、20%、30%的Al2O3-SiC-C再生料制备了铁水包用和混铁车用再生Al2O3-SiC-C砖.与原砖相比,再生砖的体积密度和常温耐压强度较高,显气孔率较低,而高温抗折强度、抗氧化性、抗渣性与原砖的差距不大.过多添加ASC再生料对再生Al2O3-SiC-C砖的高温抗折强度和抗渣侵蚀性能不利,以统料形式添加时,混铁车用Al2O3-SiC-C衬砖中ASC再生料的添加量(w)不宜超过30%.%Recycled AI2O3-SiC-C bricks for iron ladle and torpedo ladle were prepared using high alumina bauxite clinker,fused corundum,pyrauxite,SiC powder and flake graphite as starting materials,adding 10%,20% and 30% (mass percent) of recycled materials made from used AI2O3-SiC-C bricks,respectively. Compared with the original bricks,the recycled bricks have high bulk density and cold crushing strength,low apparent porosity,but similar hot modulus of rupture,oxidation resistance and slag corrosion resistance. The excessive recycled AI2O3-SiC-C material is harmful to hot modulus of rupture and slag corrosion resistance of the recycled bricks,and its proper addition in working lining bricks of torpedo ladle should not exceed 30%.

  3. Resonance Reaction in Diffusion-Influenced Bimolecular Reactions

    CERN Document Server

    Kolb, Jakob J; Dzubiella, Joachim


    We investigate the influence of a stochastically fluctuating step-barrier potential on bimolecular reaction rates by exact analytical theory and stochastic simulations. We demonstrate that the system exhibits a new resonant reaction behavior with rate enhancement if an appropriately defined fluctuation decay length is of the order of the system size. Importantly, we find that in the proximity of resonance the standard reciprocal additivity law for diffusion and surface reaction rates is violated due to the dynamical coupling of multiple kinetic processes. Together, these findings may have important repercussions on the correct interpretation of various kinetic reaction problems in complex systems, as, e.g., in biomolecular association or catalysis.

  4. NIF Gamma Reaction History (United States)

    Herrmann, H. W.; Kim, Y.; Young, C. S.; Mack, J. M.; McEvoy, A. M.; Hoffman, N. M.; Wilson, D. C.; Langenbrunner, J. R.; Evans, S.; Batha, S. H.; Stoeffl, W.; Lee, A.; Horsfield, C. J.; Rubery, M.; Miller, E. K.; Malone, R. M.; Kaufman, M. I.


    The primary objective of the NIF Gamma Reaction History (GRH) diagnostics is to provide bang time and burn width information based upon measurement of fusion gamma-rays. This is accomplished with energy-thresholded Gas Cherenkov detectors that convert MeV gamma-rays into UV/visible photons for high-bandwidth optical detection. In addition, the GRH detectors can perform γ-ray spectroscopy to explore other nuclear processes from which additional significant implosion parameters may be inferred (e.g., plastic ablator areal density). Implementation is occurring in 2 phases: 1) four PMT-based channels mounted to the outside of the NIF target chamber at ˜6 m from TCC (GRH-6m) for the 3e13-3e16 DT neutron yield range expected during the early ignition-tuning campaigns; and 2) several channels located just inside the target bay shield wall at ˜15 m from TCC (GRH-15m) with optical paths leading through the wall into well-shielded streak cameras and PMTs for the 1e16-1e20 yield range expected during the DT ignition campaign. This suite of diagnostics will allow exploration of interesting γ-ray physics well beyond the ignition campaign. Recent data from OMEGA and NIF will be shown.

  5. Hemolytic Transfusion Reactions

    Directory of Open Access Journals (Sweden)

    Fatih Mehmet Azık


    Full Text Available The prevalence of fatal hemolytic transfusion reactions (HTRs is approximately 1:200000 per unit. Acute HTRs occur during or within 24 h after administration of a blood product. Transfusion of incompatible red blood cells (RBCs, and, more rarely, of a large volume of incompatible plasma usually are the causative agents. Delayed HTRs are caused by a secondary immune response to an antigen on the donor’s RBCs. Different mechanisms lead to intra- and extravascular hemolysis, such as complete complement activation, phagocytosis of RBCs covered with C3b by macrophages after incomplete complement activation, or destruction of RBCs covered only with IgG by direct cell to cell contact with K cells. The clinical consequences of HTRs are triggered via several pathophysiological pathways. Formation of anaphylatoxins, release of cytokines causing a systemic inflammatory response syndrome, activation of the kinin system, the intrinsic clotting cascade and fibrinolysis result in hypotension, disseminated intravascular coagulation, diffuse bleeding, and disruption of microcirculation leading to renal failure and shock. In this review, the symptoms of HTR are introduced, laboratory investigations and treatment are described, and some recommendations for prevention are given. (Journal of Current Pediatrics 2011; 9: 127-32

  6. Microwave-Accelerated Organic Reactions

    Institute of Scientific and Technical Information of China (English)

    LU TaJung


    @@ The use of microwave technology in accelerating organic reactions has received intense attention leading to immense growth recently. Accordingly, we have been interested in improving the efficacy of organic processes by microwave irradiation. Here we report our results on the microwave assisted 1,3-dipolar cycloaddition reaction of nitrile oxides with allylic alcohols, the cleavage reaction of 1,3-diketones under alkaline conditions, and the formation of carbamates from isocyanates with alcohols. The reactions carried out under microwave irradiation, in general, required considerably less reaction time and afforded the desired products in higher yields than those under classical conditions. In all the cases we have studied, the procedures are simplified, the purity of the products are higher, and the cost of reaction is greatly reduced employing microwave.

  7. Microwave-Accelerated Organic Reactions

    Institute of Scientific and Technical Information of China (English)

    LU; TaJung


    The use of microwave technology in accelerating organic reactions has received intense attention leading to immense growth recently. Accordingly, we have been interested in improving the efficacy of organic processes by microwave irradiation. Here we report our results on the microwave assisted 1,3-dipolar cycloaddition reaction of nitrile oxides with allylic alcohols, the cleavage reaction of 1,3-diketones under alkaline conditions, and the formation of carbamates from isocyanates with alcohols. The reactions carried out under microwave irradiation, in general, required considerably less reaction time and afforded the desired products in higher yields than those under classical conditions. In all the cases we have studied, the procedures are simplified, the purity of the products are higher, and the cost of reaction is greatly reduced employing microwave.  ……

  8. Dinuclear Tetrapyrazolyl Palladium Complexes Exhibiting Facile Tandem Transfer Hydrogenation/Suzuki Coupling Reaction of Fluoroarylketone

    KAUST Repository

    Dehury, Niranjan


    Herein, we report an unprecedented example of dinuclear pyrazolyl-based Pd complexes exhibiting facile tandem catalysis for fluoroarylketone: Tetrapyrazolyl di-palladium complexes with varying Pd-Pd distances efficiently catalyze the tandem reaction involving transfer hydrogenation of fluoroarylketone to the corresponding alcohol and Suzuki-Miyaura cross coupling reaction of the resulting fluoroarylalcohol under moderate reaction conditions, to biaryl alcohol. The complex with the shortest Pd-Pd distance exhibits the highest tandem activity among its di-metallic analogues, and exceeds in terms of activity and selectivity the analogous mononuclear compound. The kinetics of the reaction indicates clearly that reductive transformation of haloarylketone into haloaryalcohol is the rate determining step in the tandem reaction. Interestingly while fluoroarylketone undergoes the multistep tandem catalysis, the chloro- and bromo-arylketones undergo only a single step C-C coupling reaction resulting in biarylketone as the final product. Unlike the pyrazole based Pd compounds, the precursor PdCl2 and the phosphine based relevant complexes (PPh3)2PdCl2 and (PPh3)4Pd are found to be unable to exhibit the tandem catalysis.

  9. Radiation reaction in fusion plasmas. (United States)

    Hazeltine, R D; Mahajan, S M


    The effects of a radiation reaction on thermal electrons in a magnetically confined plasma, with parameters typical of planned burning plasma experiments, are studied. A fully relativistic kinetic equation that includes the radiation reaction is derived. The associated rate of phase-space contraction is computed and the relative importance of the radiation reaction in phase space is estimated. A consideration of the moments of the radiation reaction force show that its effects are typically small in reactor-grade confined plasmas, but not necessarily insignificant.

  10. Kinematically complete chemical reaction dynamics (United States)

    Trippel, S.; Stei, M.; Otto, R.; Hlavenka, P.; Mikosch, J.; Eichhorn, C.; Lourderaj, U.; Zhang, J. X.; Hase, W. L.; Weidemüller, M.; Wester, R.


    Kinematically complete studies of molecular reactions offer an unprecedented level of insight into the dynamics and the different mechanisms by which chemical reactions occur. We have developed a scheme to study ion-molecule reactions by velocity map imaging at very low collision energies. Results for the elementary nucleophilic substitution (SN2) reaction Cl- + CH3I → ClCH3 + I- are presented and compared to high-level direct dynamics trajectory calculations. Furthermore, an improved design of the crossed-beam imaging spectrometer with full three-dimensional measurement capabilities is discussed and characterization measurements using photoionization of NH3 and photodissociation of CH3I are presented.

  11. Speeding chemical reactions by focusing

    CERN Document Server

    Lacasta, A M; Sancho, J M; Lindenberg, K


    We present numerical results for a chemical reaction of colloidal particles which are transported by a laminar fluid and are focused by periodic obstacles in such a way that the two components are well mixed and consequently the chemical reaction is speeded up. The roles of the various system parameters (diffusion coefficients, reaction rate, obstacles sizes) are studied. We show that focusing speeds up the reaction from the diffusion limited rate (t to the power -1/2) to very close to the perfect mixing rate, (t to the power -1).

  12. Pathophysiology of hemolytic transfusion reactions. (United States)

    Davenport, Robertson D


    Hemolytic transfusion reactions (HTR) are systemic reactions provoked by immunologic red blood cell (RBC) incompatibility. Clinical and experimental observations of such reactions indicate that they proceed through phases of humoral immune reaction, activation of phagocytes, productions of cytokine mediators, and wide-ranging cellular responses. HTR have many features in common with the systemic inflammatory response syndrome (SIRS). Knowledge of the pathophysiologic mechanisms in HTR suggest that newer biological agents that target complement intermediates or proinflammatory cytokines may be effective agents in the treatment of severe HTRs.

  13. Dynamic Reaction Figures: An Integrative Vehicle for Understanding Chemical Reactions (United States)

    Schultz, Emeric


    A highly flexible learning tool, referred to as a dynamic reaction figure, is described. Application of these figures can (i) yield the correct chemical equation by simply following a set of menu driven directions; (ii) present the underlying "mechanism" in chemical reactions; and (iii) help to solve quantitative problems in a number of different…

  14. Microscopic effective reaction theory for deuteron-induced reactions (United States)

    Neoh, Yuen Sim; Yoshida, Kazuki; Minomo, Kosho; Ogata, Kazuyuki


    The microscopic effective reaction theory is applied to deuteron-induced reactions. A reaction model space characterized by a p +n +A three-body model is adopted, where A is the target nucleus, and the nucleon-target potential is described by a microscopic folding model based on an effective nucleon-nucleon interaction in nuclear medium and a one-body nuclear density of A . The three-body scattering wave function in the model space is obtained with the continuum-discretized coupled-channels (CDCC) method, and the eikonal reaction theory (ERT), an extension of CDCC, is applied to the calculation of neutron removal cross sections. Elastic scattering cross sections of deuteron on 58Ni and 208Pb target nuclei at several energies are compared with experimental data. The total reaction cross sections and the neutron removal cross sections at 56 MeV on 14 target nuclei are calculated and compared with experimental values.

  15. Microscopic effective reaction theory for deuteron-induced reactions

    CERN Document Server

    Neoh, Yuen Sim; Minomo, Kosho; Ogata, Kazuyuki


    The microscopic effective reaction theory is applied to deuteron-induced reactions. A reaction model-space characterized by a $p+n+{\\rm A}$ three-body model is adopted, where A is the target nucleus, and the nucleon-target potential is described by a microscopic folding model based on an effective nucleon-nucleon interaction in nuclear medium and a one-body nuclear density of A. The three-body scattering wave function in the model space is obtained with the continuum-discretized coupled-channels method (CDCC), and the eikonal reaction theory (ERT), an extension of CDCC, is applied to the calculation of neutron removal cross sections. Elastic scattering cross sections of deuteron on $^{58}$Ni and $^{208}$Pb target nuclei at several energies are compared with experimental data. The total reaction cross sections and the neutron removal cross sections at 56 MeV on 14 target nuclei are calculated and compared with experimental values.

  16. Progress in microscopic direct reaction modeling of nucleon induced reactions

    Energy Technology Data Exchange (ETDEWEB)

    Dupuis, M.; Bauge, E.; Hilaire, S.; Lechaftois, F.; Peru, S.; Pillet, N.; Robin, C. [CEA, DAM, DIF, Arpajon (France)


    A microscopic nuclear reaction model is applied to neutron elastic and direct inelastic scatterings, and pre-equilibrium reaction. The JLM folding model is used with nuclear structure information calculated within the quasi-particle random phase approximation implemented with the Gogny D1S interaction. The folding model for direct inelastic scattering is extended to include rearrangement corrections stemming from both isoscalar and isovector density variations occurring during a transition. The quality of the predicted (n,n), (n,n{sup '}), (n,xn) and (n,n{sup '}γ) cross sections, as well as the generality of the present microscopic approach, shows that it is a powerful tool that can help improving nuclear reactions data quality. Short- and long-term perspectives are drawn to extend the present approach to more systems, to include missing reactions mechanisms, and to consistently treat both structure and reaction problems. (orig.)

  17. Refined transition-state models for proline-catalyzed asymmetric Michael reactions under basic and base-free conditions. (United States)

    Sharma, Akhilesh K; Sunoj, Raghavan B


    The stereocontrolling transition state (TS) models for C-C bond formation relying on hydrogen bonding have generally been successful in proline-catalyzed aldol, Mannich, α-amination, and α-aminoxylation reactions. However, the suitability of the hydrogen-bonding model in protic and aprotic conditions as well as under basic and base-free conditions has not been well established for Michael reactions. Through a comprehensive density functional theory investigation, we herein analyze different TS models for the stereocontrolling C-C bond formation, both in the presence and absence of a base in an aprotic solvent (THF). A refined stereocontrolling TS for the Michael reaction between cyclohexanone and nitrostyrene is proposed. The new TS devoid of hydrogen bonding between the nitro group of nitrostyrene and carboxylic acid of proline, under base-free conditions, is found to be more preferred over the conventional hydrogen-bonding model besides being able to reproduce the experimentally observed stereochemical outcome. A DBU-bound TS is identified as more suitable for rationalizing the origin of asymmetric induction under basic reaction conditions. In both cases, the most preferred approach of nitrostyrene is identified as occurring from the face anti to the carboxylic acid of proline-enamine. The predicted enantio- and diastereoselectivities are in very good agreement with the experimental observations.

  18. Mechanical stimulated reaction of metal/polymer mixed powders; Kinzoku/kobunshi kongo funmatsu no kikaiteki reiki hanno

    Energy Technology Data Exchange (ETDEWEB)

    Tobita, M.; Sakakibara, A.; Takemoto, Y. [Okayama University, Okayama (Japan). Faculty of Engineering; Iwabu, H. [Kurare Co. Ltd., Osaka (Japan)


    Mechanical grinding (MG) with mechanically stimulated reaction was performed on metal/polymer mixed powders. The starting materials used in this study were the metals of Mg, Ti and Mg{sub 2}Ni powders, arid polymer of PTFE, PVC and PE powders. The MG process was investigated using XRD, IR, SEM and TEM. According to XRD results, magnesium fluoride (MgF{sub 2}, TiF{sub 2}) and chloride (MgCl{sub 2}) were detected from MG products of the Mg/PTFE, Ti/PTFE and Mg/PVC blending systems, respectively. Explosive reaction was found during MG of both Mg/PTFE and Ti/PTFE. It was also confirmed by XRD results that the production of MgF{sub 2} had already been formed just before the explosive reaction in Mg/PTFE system. It was found from IR analysis that C-C single bond in the polymers, not only both in PTFE and PVC but also in PE, changed to double bond C=C. Hydrogen produced due to decomposition of PE on blending Mg{sub 2}Ni/PE was absorbed into C-Mg{sub 2}Ni-H as amorphous solutes. These mechanically stimulated reaction was powerful method for decomposition of engineering plastics. (author)

  19. Formation of nitrogen-containing polycyclic cations by gas-phase and intracluster reactions of acetylene with the pyridinium and pyrimidinium ions. (United States)

    Soliman, Abdel-Rahman; Hamid, Ahmed M; Attah, Isaac; Momoh, Paul; El-Shall, M Samy


    Here, we present evidence from laboratory experiments for the formation of nitrogen-containing complex organic ions by sequential reactions of acetylene with the pyridinium and pyrimidinium ions in the gas phase and within ionized pyridine-acetylene binary clusters. Additions of five and two acetylene molecules onto the pyridinium and pyrimidinium ions, respectively, at room temperature are observed. Second-order rate coefficients of the overall reaction of acetylene with the pyridinium and pyrimidinium ions are measured as 9.0 × 10(-11) and 1.4 × 10(-9) cm(3) s(-1), respectively, indicating reaction efficiencies of about 6% and 100%, respectively, at room temperature. At high temperatures, only two acetylene molecules are added to the pyridinium and pyrimidinium ions, suggesting covalent bond formation. A combination of ion dissociation and ion mobility experiments with DFT calculations reveals that the addition of acetylene into the pyridinium ion occurs through the N-atom of the pyridinium ion. The relatively high reaction efficiency is consistent with the absence of a barrier in the exothermic N-C bond forming reaction leading to the formation of the C(7)H(7)N(•+) covalent adduct. An exothermic addition/H-elimination reaction of acetylene with the C(7)H(7)N(•+) adduct is observed leading to the formation of a bicyclic quinolizinium cation (C(9)H(8)N(+)). Similar chemistry is observed in the sequential reactions of acetylene with the pyrimidinium ion. The second acetylene addition onto the pyrimidinium ion involves an exclusive addition/H-elimination reaction at room temperature leading to the formation of a bicyclic pyrimidinium cation (C(8)H(7)N(2)(+)). The high reactivity of the pyridinium and pyrimidinium ions toward acetylene is in sharp contrast to the very low reactivity of the benzene cation, which has a reaction efficiency of 10(-4)-10(-5). This indicates that the presence of a nitrogen atom within the aromatic ring enhances the ring growth


    Institute of Scientific and Technical Information of China (English)


    @@ Personal history Mr. CC Tung was born into theworld of shipping but had to earn hisposition as the leader of OrientOverseas (International) Limited(OOIL) through hard work and vision.Mr. Tung was educated and trained asan engineer and received his Bachelorof Science Degree from the Universityof Liverpool, England. He acquired aMaster's Degree in MechanicalEngineering at the MassachusettsInstitute of Technology in the UnitedStates. In 1968, he joined the familybusiness in New York, where, for overthe next two decades, he managed thecompany's US operations andexplored business opportunities inSouth America.