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Sample records for merging photoredox catalysis

  1. The Development of Visible-Light Photoredox Catalysis in Flow.

    Science.gov (United States)

    Garlets, Zachary J; Nguyen, John D; Stephenson, Corey R J

    2014-04-01

    Visible-light photoredox catalysis has recently emerged as a viable alternative for radical reactions otherwise carried out with tin and boron reagents. It has been recognized that by merging photoredox catalysis with flow chemistry, slow reaction times, lower yields, and safety concerns may be obviated. While flow reactors have been successfully applied to reactions carried out with UV light, only recent developments have demonstrated the same potential of flow reactors for the improvement of visible-light-mediated reactions. This review examines the initial and continuing development of visible-light-mediated photoredox flow chemistry by exemplifying the benefits of flow chemistry compared with conventional batch techniques.

  2. Generating carbyne equivalents with photoredox catalysis

    Science.gov (United States)

    Wang, Zhaofeng; Herraiz, Ana G.; Del Hoyo, Ana M.; Suero, Marcos G.

    2018-02-01

    Carbon has the unique ability to bind four atoms and form stable tetravalent structures that are prevalent in nature. The lack of one or two valences leads to a set of species—carbocations, carbanions, radicals and carbenes—that is fundamental to our understanding of chemical reactivity. In contrast, the carbyne—a monovalent carbon with three non-bonded electrons—is a relatively unexplored reactive intermediate; the design of reactions involving a carbyne is limited by challenges associated with controlling its extreme reactivity and the lack of efficient sources. Given the innate ability of carbynes to form three new covalent bonds sequentially, we anticipated that a catalytic method of generating carbynes or related stabilized species would allow what we term an ‘assembly point’ disconnection approach for the construction of chiral centres. Here we describe a catalytic strategy that generates diazomethyl radicals as direct equivalents of carbyne species using visible-light photoredox catalysis. The ability of these carbyne equivalents to induce site-selective carbon-hydrogen bond cleavage in aromatic rings enables a useful diazomethylation reaction, which underpins sequencing control for the late-stage assembly-point functionalization of medically relevant agents. Our strategy provides an efficient route to libraries of potentially bioactive molecules through the installation of tailored chiral centres at carbon-hydrogen bonds, while complementing current translational late-stage functionalization processes. Furthermore, we exploit the dual radical and carbene character of the generated carbyne equivalent in the direct transformation of abundant chemical feedstocks into valuable chiral molecules.

  3. Stabilizing ultrasmall Au clusters for enhanced photoredox catalysis.

    Science.gov (United States)

    Weng, Bo; Lu, Kang-Qiang; Tang, Zichao; Chen, Hao Ming; Xu, Yi-Jun

    2018-04-18

    Recently, loading ligand-protected gold (Au) clusters as visible light photosensitizers onto various supports for photoredox catalysis has attracted considerable attention. However, the efficient control of long-term photostability of Au clusters on the metal-support interface remains challenging. Herein, we report a simple and efficient method for enhancing the photostability of glutathione-protected Au clusters (Au GSH clusters) loaded on the surface of SiO 2 sphere by utilizing multifunctional branched poly-ethylenimine (BPEI) as a surface charge modifying, reducing and stabilizing agent. The sequential coating of thickness controlled TiO 2 shells can further significantly improve the photocatalytic efficiency, while such structurally designed core-shell SiO 2 -Au GSH clusters-BPEI@TiO 2 composites maintain high photostability during longtime light illumination conditions. This joint strategy via interfacial modification and composition engineering provides a facile guideline for stabilizing ultrasmall Au clusters and rational design of Au clusters-based composites with improved activity toward targeting applications in photoredox catalysis.

  4. Preparative semiconductor photoredox catalysis: An emerging theme in organic synthesis

    Directory of Open Access Journals (Sweden)

    David W. Manley

    2015-09-01

    Full Text Available Heterogeneous semiconductor photoredox catalysis (SCPC, particularly with TiO2, is evolving to provide radically new synthetic applications. In this review we describe how photoactivated SCPCs can either (i interact with a precursor that donates an electron to the semiconductor thus generating a radical cation; or (ii interact with an acceptor precursor that picks up an electron with production of a radical anion. The radical cations of appropriate donors convert to neutral radicals usually by loss of a proton. The most efficient donors for synthetic purposes contain adjacent functional groups such that the neutral radicals are resonance stabilized. Thus, ET from allylic alkenes and enol ethers generated allyl type radicals that reacted with 1,2-diazine or imine co-reactants to yield functionalized hydrazones or benzylanilines. SCPC with tertiary amines enabled electron-deficient alkenes to be alkylated and furoquinolinones to be accessed. Primary amines on their own led to self-reactions involving C–N coupling and, with terminal diamines, cyclic amines were produced. Carboxylic acids were particularly fruitful affording C-centered radicals that alkylated alkenes and took part in tandem addition cyclizations producing chromenopyrroles; decarboxylative homo-dimerizations were also observed. Acceptors initially yielding radical anions included nitroaromatics and aromatic iodides. The latter led to hydrodehalogenations and cyclizations with suitable precursors. Reductive SCPC also enabled electron-deficient alkenes and aromatic aldehydes to be hydrogenated without the need for hydrogen gas.

  5. Controlled trifluoromethylation reactions of alkynes through visible-light photoredox catalysis.

    Science.gov (United States)

    Iqbal, Naeem; Jung, Jaehun; Park, Sehyun; Cho, Eun Jin

    2014-01-07

    The control of a reaction that can form multiple products is a highly attractive and challenging concept in synthetic chemistry. A set of valuable CF3 -containing molecules, namely trifluoromethylated alkenyl iodides, alkenes, and alkynes, were selectively generated from alkynes and CF3 I by environmentally benign and efficient visible-light photoredox catalysis. Subtle differences in the combination of catalyst, base, and solvent enabled the control of reactivity and selectivity for the reaction between an alkyne and CF3 I. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Domino-Fluorination-Protodefluorination Enables Decarboxylative Cross-Coupling of α-Oxocarboxylic Acids with Styrene via Photoredox Catalysis.

    Science.gov (United States)

    Zhang, Muliang; Xi, Junwei; Ruzi, Rehanguli; Li, Nan; Wu, Zhongkai; Li, Weipeng; Zhu, Chengjian

    2017-09-15

    Domino-fluorination-protodefluorination decarboxylative cross-coupling of α-keto acids with styrene has been developed via photoredox catalysis. The critical part of this strategy is the formation of the carbon-fluorine (C-F) bond by the capture of a carbon-centered radical intermediate, which will overcome side reactions during the styrene radical functionalization process. Experimental studies have provided evidence indicating a domino-fluorination-protodefluorination pathway with α-keto acid initiating the photoredox cycle. The present catalytic protocol also affords a novel approach for the construction of α,β-unsaturated ketones under mild conditions.

  7. Rapid trifluoromethylation and perfluoroalkylation of five-membered heterocycles by photoredox catalysis in continuous flow.

    Science.gov (United States)

    Straathof, Natan J W; Gemoets, Hannes P L; Wang, Xiao; Schouten, Jaap C; Hessel, Volker; Noël, Timothy

    2014-06-01

    Trifluoromethylated and perfluoroalkylated heterocycles are important building blocks for the synthesis of numerous pharmaceutical products, agrochemicals and are widely applied in material sciences. To date, trifluoromethylated and perfluoroalkylated hetero-aromatic systems can be prepared utilizing visible light photoredox catalysis methodologies in batch. While several limitations are associated with these batch protocols, the application of microflow technology could greatly enhance and intensify these reactions. A simple and straightforward photocatalytic trifluoromethylation and perfluoroalkylation method has been developed in continuous microflow, using commercially available photocatalysts and microflow components. A selection of five-membered hetero-aromatics were successfully trifluoromethylated (12 examples) and perfluoroalkylated (5 examples) within several minutes (8-20 min). © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Material-Efficient Microfluidic Platform for Exploratory Studies of Visible-Light Photoredox Catalysis.

    Science.gov (United States)

    Coley, Connor W; Abolhasani, Milad; Lin, Hongkun; Jensen, Klavs F

    2017-08-07

    We present an automated microfluidic platform for in-flow studies of visible-light photoredox catalysis in liquid or gas-liquid reactions at the 15 μL scale. An oscillatory flow strategy enables a flexible residence time while preserving the mixing and heat transfer advantages of flow systems. The adjustable photon flux made possible with the platform is characterized using actinometry. Case studies of oxidative hydroxylation of phenylboronic acids and dimerization of thiophenol demonstrate the capabilities and advantages of the system. Reaction conditions identified through droplet screening translate directly to continuous synthesis with minor platform modifications. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Direct Aldehyde C-H Arylation and Alkylation via the Combination of Nickel, Hydrogen Atom Transfer, and Photoredox Catalysis.

    Science.gov (United States)

    Zhang, Xiaheng; MacMillan, David W C

    2017-08-23

    A mechanism that enables direct aldehyde C-H functionalization has been achieved via the synergistic merger of photoredox, nickel, and hydrogen atom transfer catalysis. This mild, operationally simple protocol transforms a wide variety of commercially available aldehydes, along with aryl or alkyl bromides, into the corresponding ketones in excellent yield. This C-H abstraction coupling technology has been successfully applied to the expedient synthesis of the medicinal agent haloperidol.

  10. Asymmetric Organocatalysis and Photoredox Catalysis for the α-Functionalization of Tetrahydroisoquinolines

    KAUST Repository

    Hou, Hong

    2018-03-14

    The asymmetric α‐alkylation of tetrahydroisoquinolines with cyclic ketones has been accomplished in the presence of a combined catalytic system consisting of a visible‐light photoredox catalyst and a chiral primary amine organocatalyst. The desired products were obtained in good yields, high enantioselectivity, and good to excellent diastereoselectivity. (PC: photoredox cycle, EN: enamine cycle).

  11. Asymmetric Organocatalysis and Photoredox Catalysis for the α-Functionalization of Tetrahydroisoquinolines

    KAUST Repository

    Hou, Hong; Zhu, Shaoqun; Atodiresei, Iuliana; Rueping, Magnus

    2018-01-01

    The asymmetric α‐alkylation of tetrahydroisoquinolines with cyclic ketones has been accomplished in the presence of a combined catalytic system consisting of a visible‐light photoredox catalyst and a chiral primary amine organocatalyst. The desired products were obtained in good yields, high enantioselectivity, and good to excellent diastereoselectivity. (PC: photoredox cycle, EN: enamine cycle).

  12. Amine Functionalization via Oxidative Photoredox Catalysis: Methodology Development and Complex Molecule Synthesis

    Science.gov (United States)

    2016-01-01

    Conspectus While the use of visible light to drive chemical reactivity is of high importance to the development of environmentally benign chemical transformations, the concomitant use of a stoichiometric electron donor or acceptor is often required to steer the desired redox behavior of these systems. The low-cost and ubiquity of tertiary amine bases has led to their widespread use as reductive additives in photoredox catalysis. Early use of trialkylamines in this context was focused on their role as reductive excited state quenchers of the photocatalyst, which in turn provides a more highly reducing catalytic intermediate. In this Account, we discuss some of the observations and thought processes that have led from our use of amines as reductive additives to their use as complex substrates and intermediates for natural product synthesis. Early attempts by our group to construct key carbon–carbon bonds via free-radical intermediates led to the observation that some trialkylamines readily behave as efficient hydrogen atom donors under redox-active photochemical conditions. In the wake of in-depth mechanistic studies published in the 1970s, 1980s and 1990s, this understanding has in turn allowed for a systematic approach to the design of a number of photochemical methodologies through rational tuning of the amine component. Minimization of the C–H donicity of the amine additive was found to promote desired C–C bond formation in a number of contexts, and subsequent elucidation of the amine’s redox fate has sparked a reevaluation of the amine’s role from that of reagent to that of substrate. The reactivity of tertiary amines in these photochemical systems is complex, and allows for a number of mechanistic possibilities that are not necessarily mutually exclusive. A variety of combinations of single-electron oxidation, C–H abstraction, deprotonation, and β-scission result in the formation of reactive intermediates such as α-amino radicals and iminium ions

  13. Synthesis of 2,4,6-Trisubstituted Pyridines by Oxidative Eosin Y Photoredox Catalysis.

    Science.gov (United States)

    Rohokale, Rajendra S; Koenig, Burkhard; Dhavale, Dilip D

    2016-08-19

    Eosin Y, an organic dye, was activated as a photoredox catalyst in the presence of molecular oxygen using visible light and, when it was used in the reaction of aryl ketones and benzyl amines, afforded good yields (52-87%) of 2,4,6-triarylpyridines (21 examples) at ambient temperature. The aryl groups at the 2- and 6-positions are derived from ketones, while benzyl amine plays the dual role of providing an aryl functionality at the 4-position of pyridine as well as being a nitrogen donor.

  14. The chemistry of amine radical cations produced by visible light photoredox catalysis

    Directory of Open Access Journals (Sweden)

    Jie Hu

    2013-10-01

    Full Text Available Amine radical cations are highly useful reactive intermediates in amine synthesis. They have displayed several modes of reactivity leading to some highly sought-after synthetic intermediates including iminium ions, α-amino radicals, and distonic ions. One appealing method to access amine radical cations is through one-electron oxidation of the corresponding amines under visible light photoredox conditions. This approach and subsequent chemistries are emerging as a powerful tool in amine synthesis. This article reviews synthetic applications of amine radical cations produced by visible light photocatalysis.

  15. Direct C–H trifluoromethylation of di- and trisubstituted alkenes by photoredox catalysis

    Directory of Open Access Journals (Sweden)

    Ren Tomita

    2014-05-01

    Full Text Available Background: Trifluoromethylated alkene scaffolds are known as useful structural motifs in pharmaceuticals and agrochemicals as well as functional organic materials. But reported synthetic methods usually require multiple synthetic steps and/or exhibit limitation with respect to access to tri- and tetrasubstituted CF3-alkenes. Thus development of new methodologies for facile construction of Calkenyl–CF3 bonds is highly demanded.Results: The photoredox reaction of alkenes with 5-(trifluoromethyldibenzo[b,d]thiophenium tetrafluoroborate, Umemoto’s reagent, as a CF3 source in the presence of [Ru(bpy3]2+ catalyst (bpy = 2,2’-bipyridine under visible light irradiation without any additive afforded CF3-substituted alkenes via direct Calkenyl–H trifluoromethylation. 1,1-Di- and trisubstituted alkenes were applicable to this photocatalytic system, providing the corresponding multisubstituted CF3-alkenes. In addition, use of an excess amount of the CF3 source induced double C–H trifluoromethylation to afford geminal bis(trifluoromethylalkenes.Conclusion: A range of multisubstituted CF3-alkenes are easily accessible by photoredox-catalyzed direct C–H trifluoromethylation of alkenes under mild reaction conditions. In particular, trifluoromethylation of triphenylethene derivatives, from which synthetically valuable tetrasubstituted CF3-alkenes are obtained, have never been reported so far. Remarkably, the present facile and straightforward protocol is extended to double trifluoromethylation of alkenes.

  16. Enantioselective rhodium/ruthenium photoredox catalysis en route to chiral 1,2-aminoalcohols.

    Science.gov (United States)

    Ma, Jiajia; Harms, Klaus; Meggers, Eric

    2016-08-09

    A rhodium-based chiral Lewis acid catalyst combined with [Ru(bpy)3](PF6)2 as a photoredox sensitizer allows for the visible-light-activated redox coupling of α-silylamines with 2-acyl imidazoles to afford, after desilylation, 1,2-amino-alcohols in yields of 69-88% and with high enantioselectivity (54-99% ee). The reaction is proposed to proceed via an electron exchange between the α-silylamine (electron donor) and the rhodium-chelated 2-acyl imidazole (electron acceptor), followed by a stereocontrolled radical-radical reaction. Substrate scope and control experiments reveal that the trimethylsilyl group plays a crucial role in this reductive umpolung of the carbonyl group.

  17. Cross-Coupling of Sodium Sulfinates with Aryl, Heteroaryl and Vinyl Halides by Nickel/photoredox dual catalysis

    KAUST Repository

    Yue, Huifeng

    2017-12-06

    An efficient photoredox/nickel dual catalyzed sulfonylation reaction of aryl, heteroaryl, and vinyl halides has been achieved for the first time. This newly developed sulfonylation protocol provides a versatile method for the synthesis of diverse aromatic sulfones at room temperature and shows excellent functional group tolerance. The electrophilic coupling partners are not limited to aryl, heteroaryl and vinyl bromides but also less reactive aryl chlorides are suitable substrates for this transformation.

  18. Cross-Coupling of Sodium Sulfinates with Aryl, Heteroaryl and Vinyl Halides by Nickel/photoredox dual catalysis

    KAUST Repository

    Yue, Huifeng; Zhu, Chen; Rueping, Magnus

    2017-01-01

    An efficient photoredox/nickel dual catalyzed sulfonylation reaction of aryl, heteroaryl, and vinyl halides has been achieved for the first time. This newly developed sulfonylation protocol provides a versatile method for the synthesis of diverse aromatic sulfones at room temperature and shows excellent functional group tolerance. The electrophilic coupling partners are not limited to aryl, heteroaryl and vinyl bromides but also less reactive aryl chlorides are suitable substrates for this transformation.

  19. Selective Hydrogen Atom Abstraction through Induced Bond Polarization: Direct α-Arylation of Alcohols through Photoredox, HAT, and Nickel Catalysis.

    Science.gov (United States)

    Twilton, Jack; Christensen, Melodie; DiRocco, Daniel A; Ruck, Rebecca T; Davies, Ian W; MacMillan, David W C

    2018-05-04

    The combination of nickel metallaphotoredox catalysis, hydrogen atom transfer catalysis, and a Lewis acid activation mode, has led to the development of an arylation method for the selective functionalization of alcohol α-hydroxy C-H bonds. This approach employs zinc-mediated alcohol deprotonation to activate α-hydroxy C-H bonds while simultaneously suppressing C-O bond formation by inhibiting the formation of nickel alkoxide species. The use of Zn-based Lewis acids also deactivates other hydridic bonds such as α-amino and α-oxy C-H bonds. This approach facilitates rapid access to benzylic alcohols, an important motif in drug discovery. A 3-step synthesis of the drug Prozac exemplifies the utility of this new method. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Reductive Umpolung of Carbonyl Derivatives with Visible-Light Photoredox Catalysis: Direct Access to Vicinal Diamines and Amino Alcohols via α-Amino Radicals and Ketyl Radicals

    KAUST Repository

    Fava, Eleonora; Millet, Anthony; Nakajima, Masaki; Loescher, Sebastian; Rueping, Magnus

    2016-01-01

    Visible-light-mediated photoredox-catalyzed aldimine-aniline and aldehyde-aniline couplings have been realized. The reductive single electron transfer (SET) umpolung of various carbonyl derivatives enabled the generation of intermediary ketyl and α-amino radical anions, which were utilized for the synthesis of unsymmetrically substituted 1,2-diamines and amino alcohols. Anilines can be coupled with aldimines or aldehydes in a visible-light-mediated photoredox-catalyzed process. Reductive single electron transfer (SET) umpolung of the carbonyl derivatives leads to the generation of intermediary ketyl and α-amino radical anions, which were used for the synthesis of unsymmetrically substituted 1,2-diamines and amino alcohols.

  1. Reductive Umpolung of Carbonyl Derivatives with Visible-Light Photoredox Catalysis: Direct Access to Vicinal Diamines and Amino Alcohols via α-Amino Radicals and Ketyl Radicals

    KAUST Repository

    Fava, Eleonora

    2016-05-02

    Visible-light-mediated photoredox-catalyzed aldimine-aniline and aldehyde-aniline couplings have been realized. The reductive single electron transfer (SET) umpolung of various carbonyl derivatives enabled the generation of intermediary ketyl and α-amino radical anions, which were utilized for the synthesis of unsymmetrically substituted 1,2-diamines and amino alcohols. Anilines can be coupled with aldimines or aldehydes in a visible-light-mediated photoredox-catalyzed process. Reductive single electron transfer (SET) umpolung of the carbonyl derivatives leads to the generation of intermediary ketyl and α-amino radical anions, which were used for the synthesis of unsymmetrically substituted 1,2-diamines and amino alcohols.

  2. Merging Visible Light Photoredox Catalysis with Metal Catalyzed C–H Activations: On the Role of Oxygen and Superoxide Ions as Oxidants

    KAUST Repository

    Fabry, David C.

    2016-08-24

    ConspectusThe development of efficient catalytic systems for direct aromatic C-H bond functionalization is a long-desired goal of chemists, because these protocols provide environmental friendly and waste-reducing alternatives to classical methodologies for C-C and C-heteroatom bond formation. A key challenge for these transformations is the reoxidation of the in situ generated metal hydride or low-valent metal complexes of the primary catalytic bond forming cycle. To complete the catalytic cycle and to regenerate the C-H activation catalyst, (super)stoichiometric amounts of Cu(II) or Ag(I) salts have often been applied. Recently,

  3. Merging Visible Light Photoredox Catalysis with Metal Catalyzed C–H Activations: On the Role of Oxygen and Superoxide Ions as Oxidants

    KAUST Repository

    Fabry, David C.; Rueping, Magnus

    2016-01-01

    ConspectusThe development of efficient catalytic systems for direct aromatic C-H bond functionalization is a long-desired goal of chemists, because these protocols provide environmental friendly and waste-reducing alternatives to classical methodologies for C-C and C-heteroatom bond formation. A key challenge for these transformations is the reoxidation of the in situ generated metal hydride or low-valent metal complexes of the primary catalytic bond forming cycle. To complete the catalytic cycle and to regenerate the C-H activation catalyst, (super)stoichiometric amounts of Cu(II) or Ag(I) salts have often been applied. Recently,

  4. Decarboxylative Aminomethylation of Aryl- and Vinylsulfonates through Combined Nickel- and Photoredox-Catalyzed Cross-Coupling

    KAUST Repository

    Fan, Lulu; Jia, Jiaqi; Hou, Hong; Lefebvre, Quentin; Rueping, Magnus

    2016-01-01

    A mild approach for the decarboxylative aminomethylation of aryl sulfonates by the combination of photoredox and nickel catalysis through C−O bond cleavage is described for the first time. A wide range of aryl triflates as well as aryl mesylates, tosylates and alkenyl triflates afford the corresponding products in good to excellent yields.

  5. Decarboxylative Aminomethylation of Aryl- and Vinylsulfonates through Combined Nickel- and Photoredox-Catalyzed Cross-Coupling

    KAUST Repository

    Fan, Lulu

    2016-09-23

    A mild approach for the decarboxylative aminomethylation of aryl sulfonates by the combination of photoredox and nickel catalysis through C−O bond cleavage is described for the first time. A wide range of aryl triflates as well as aryl mesylates, tosylates and alkenyl triflates afford the corresponding products in good to excellent yields.

  6. Oxidative Photoredox-Catalytic Activation of Aliphatic Nucleophiles for C(sp3)-C(sp2) Cross-Coupling Reactions

    Czech Academy of Sciences Publication Activity Database

    Jahn, Emanuela; Jahn, Ullrich

    2014-01-01

    Roč. 53, č. 49 (2014), s. 13326-13328 ISSN 1433-7851 Institutional support: RVO:61388963 Keywords : amino acids * cross - coupling * nickel * persistent radical effect * photoredox catalysis Subject RIV: CC - Organic Chemistry Impact factor: 11.261, year: 2014

  7. Preparative semiconductor photoredox catalysis: An emerging theme in organic synthesis

    Czech Academy of Sciences Publication Activity Database

    Manley, David W.; Walton, J. C.

    2015-01-01

    Roč. 11, Sep 9 (2015), s. 1570-1582 ISSN 1860-5397 Institutional support: RVO:61388963 Keywords : carboxylic acids * free radicals * organic synthesis * photocatalysis * titania Subject RIV: CC - Organic Chemistry Impact factor: 2.697, year: 2015 http://www.beilstein-journals.org/bjoc/single/articleFullText.htm?publicId=1860-5397-11-173

  8. Cation Radical Accelerated Nucleophilic Aromatic Substitution via Organic Photoredox Catalysis.

    Science.gov (United States)

    Tay, Nicholas E S; Nicewicz, David A

    2017-11-15

    Nucleophilic aromatic substitution (S N Ar) is a direct method for arene functionalization; however, it can be hampered by low reactivity of arene substrates and their availability. Herein we describe a cation radical-accelerated nucleophilic aromatic substitution using methoxy- and benzyloxy-groups as nucleofuges. In particular, lignin-derived aromatics containing guaiacol and veratrole motifs were competent substrates for functionalization. We also demonstrate an example of site-selective substitutive oxygenation with trifluoroethanol to afford the desired trifluoromethylaryl ether.

  9. Photoredox-Based Actuation of an Artificial Molecular Muscle.

    Science.gov (United States)

    Liles, Kevin P; Greene, Angelique F; Danielson, Mary K; Colley, Nathan D; Wellen, Andrew; Fisher, Jeremy M; Barnes, Jonathan C

    2018-01-24

    The use of light to actuate materials is advantageous because it represents a cost-effective and operationally straightforward way to introduce energy into a stimuli-responsive system. Common strategies for photoinduced actuation of materials typically rely on light irradiation to isomerize azobenzene or spiropyran derivatives, or to induce unidirectional rotation of molecular motors incorporated into a 3D polymer network. Although interest in photoredox catalysis has risen exponentially in the past decade, there are far fewer examples where photoinduced electron transfer (PET) processes are employed to actuate materials. Here, a novel mode of actuation in a series of redox-responsive hydrogels doped with a visible-light-absorbing ruthenium-based photocatalyst is reported. The hydrogels are composed primarily of polyethylene glycol and low molar concentrations of a unimolecular electroactive polyviologen that is activated through a PET mechanism. The rate and degree of contraction of the hydrogels are measured over several hours while irradiating with blue light. Likewise, the change in mechanical properties-determined through oscillatory shear rheology experiments-is assessed as a function of polyviologen concentration. Finally, an artificial molecular muscle is fabricated using the best-performing hydrogel composition, and its ability to perform work, while irradiated, is demonstrated by lifting a small weight. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Environmental catalysis

    International Nuclear Information System (INIS)

    Montes Consuelo; Villa, Aida Luz

    1996-01-01

    The term environmental catalysis has been used lately to refer to a variety of applications of the catalysis, those which, they have grouped in the following categories: a) Control of emissions (chimney Gases and gases of the vehicles, Compound Organic Volatile (VOC), Scents, Chlorofluorocarbons) b) Conversion of having undone solids or liquids. C) Selective obtaining of alternating products that replace polluting compounds. d)replacement of catalysis environmentally dangerous And e)Development of catalysts for the obtaining of valuable chemical products without the formation of polluting by-products. In the group of Environmental Catalysis comes working in the first category, Particularly, in the exploration of active catalysts in the decrease of the emissions coming from combustion systems, carbon monoxide, hydrocarbons, nitrogen oxides (NOx), N20 and sulfur (SOx). Our fundamental premise is that the molecular meshes are catalytic potential for the development of a technology environmentally clean. These materials understand a class of inorganic compound with unique properties and intimately related with the structure. The net of the molecular meshes consists on tetrahedral configuration atoms (Al,Si, P, etc.) united to each other by oxygen atoms. As a result they are not formed three-dimensional structures alone with channels and cavities but also, with openings bounded by rings that consist of a certain number of tetrahedral atoms

  11. Asymmetric Catalysis with Organic Azides and Diazo Compounds Initiated by Photoinduced Electron Transfer.

    Science.gov (United States)

    Huang, Xiaoqiang; Webster, Richard D; Harms, Klaus; Meggers, Eric

    2016-09-28

    Electron-acceptor-substituted aryl azides and α-diazo carboxylic esters are used as substrates for visible-light-activated asymmetric α-amination and α-alkylation, respectively, of 2-acyl imidazoles catalyzed by a chiral-at-metal rhodium-based Lewis acid in combination with a photoredox sensitizer. This novel proton- and redox-neutral method provides yields of up to 99% and excellent enantioselectivities of up to >99% ee with broad functional group compatibility. Mechanistic investigations suggest that an intermediate rhodium enolate complex acts as a reductive quencher to initiate a radical process with the aryl azides and α-diazo carboxylic esters serving as precursors for nitrogen and carbon-centered radicals, respectively. This is the first report on using aryl azides and α-diazo carboxylic esters as substrates for asymmetric catalysis under photoredox conditions. These reagents have the advantage that molecular nitrogen is the leaving group and sole byproduct in this reaction.

  12. Catalysis studies

    International Nuclear Information System (INIS)

    Taylor, T.N.; Ellis, W.P.

    1977-11-01

    The New Research Initiatives Program (NRIP) project on catalysis in Los Alamos Scientific Laboratory (LASL) Group CMB-8 has made significant progress towards performing the first basic in situ experimental studies of heterogeneous catalysis on solid compound surfaces in a LEED-Auger system. To further understand the surface crystallography of a possible catalyst compound, LEED-Auger measurements were made on UO 2 (approximately 100) vicinal surfaces. These (approximately 100) vicinal surfaces were shown to decompose irreversibly into lower index facets, including prominent (100) facets, at temperatures below those needed for creation of lowest index faceting on (approximately 111) vicinal surfaces. LEED examination of fully faceted surfaces from both types of UO 2 vicinal cuts did not show evidence of cyclopropane or propene chemisorption. The existing LEED-Auger system was modified to allow catalytic reactions at approximately less than 10 -3 torr. A sample holder, specifically designed for catalysis measurements in the modified system, was tested while examining single crystals of CoO and Cr 2 O 3 . Extensive LEED-Auger measurements were made on CoO in vacuo and in the presence of light hydrocarbons and alcohols plus H 2 O, NO, and NH 3 . No chemisorptive behavior was observed except with H 2 O in the presence of the electron beam. Although only examined briefly, the Cr 2 O 3 was remarkable for the sharp LEED features obtained prior to any surface treatment in the vacuum system

  13. Membrane-Organized Chemical Photoredox Systems

    Energy Technology Data Exchange (ETDEWEB)

    Hurst, James K.

    2014-09-18

    This project has three interrelated goals relevant to solar water photolysis, which are to develop: (1) vesicle-organized assemblies for H2 photoproduction that utilize pyrylium and structurally related compounds as combined photosensitizers and cyclic electroneutral transmembrane electron carriers; (2) transmembrane redox systems whose reaction rates can be modulated by light; and (3) homogeneous catalysts for water oxidation. . In area (1), initial efforts to photogenerate H2 from vectorially-organized vesicles containing occluded colloidal Pt and commonly available pyrylium ions as transmembrane redox mediators were unsuccessful. New pyrylium compounds with significantly lower reduction potentials have been synthesized to address this problem, their apparent redox potentials in functioning systems have been now evaluated by using a series of occluded viologens, and H2 photoproduction has been demonstrated in continuous illumination experiments. In area (2), spirooxazine-quinone dyads have been synthesized and their capacity to function as redox mediators across bilayer membranes has been evaluated through continuous photolysis and transient spectrophotometric measurements. Photoisomerization of the spiro moiety to the ring-open mero form caused net quantum yields to decrease significantly, providing a basis for photoregulation of transmembrane redox. Research on water oxidation (area 3) has been directed at understanding mechanisms of catalysis by cis,cis-[(bpy)2Ru(OH2)]2O4+ and related polyimine complexes. Using a variety of physical techniques, we have: (i) identified the redox state of the complex ion that is catalytically active; (ii) shown using 18O isotopic labeling that there are two reaction pathways, both of which involve participation of solvent H2O; and (iii) detected and characterized by EPR and resonance Raman spectroscopies new species which may be key intermediates in the catalytic cycle.

  14. Environmental catalysis

    Energy Technology Data Exchange (ETDEWEB)

    Janssen, F.J.J.G.; Santen, R.A. van (eds.)

    1999-04-01

    Catalysts play key roles in the production of clean fuels, the conversion of waste and green raw materials into energy, clean combustion engines including control of NOx and soot production and reduction of greenhouse gases, production of clean water and polymers, as well as reduction from polymers to monometers. This book contains 15 chapters by experts in the field, on the theme of catalysts used to create a sustainable society. Chapters include: catalysts for renewable energy and chemicals, fuel cells, catalytic processes for high-quality transportation fuels; oxidative coupling of methane, methane utilisation via synthesis gas generation, catalytic combustion, catalytical removal of nitrate from water, contribution of catalysis towards the reduction of atmospheric air pollution (CO{sub 2}, CFCs, N{sub 2}O), ozone), emission control from mobile sources and from stationary sources, and deactivation, regeneration and recycling of hydroprocessing catalysts.

  15. Synthesis of quaternary aryl phosphonium salts: photoredox-mediated phosphine arylation.

    Science.gov (United States)

    Fearnley, A F; An, J; Jackson, M; Lindovska, P; Denton, R M

    2016-04-11

    We report a synthesis method for the construction of quaternary aryl phoshonium salts at ambient temperature. The regiospecific reaction involves the coupling of phosphines with aryl radicals derived from diaryliodonium salts under photoredox conditions.

  16. Merge of terminological resources

    DEFF Research Database (Denmark)

    Henriksen, Lina; Braasch, Anna

    2012-01-01

    In our globalized world, the amount of cross-national communication increases rapidly, which also calls for easy access to multi-lingual high quality terminological resources. Sharing of terminology resources is currently becoming common practice, and efficient strategies for integration...... – or merging – of terminology resources are strongly needed. This paper discusses prerequisites for successful merging with the focus on identification of candidate duplicates of a subject domain found in the resources to be merged, and it describes automatic merging strategies to be applied to such duplicates...... in electronic terminology resources. Further, some perspectives of manual, supplementary assessment methods supporting the automatic procedures are sketched. Our considerations are primarily based on experience gained in the IATE and EuroTermBank projects, as merging was a much discussed issue in both projects....

  17. Merging {DBMs} Efficiently

    DEFF Research Database (Denmark)

    David, Alexandre

    2005-01-01

    In this paper we present different algorithms to reduce the number of DBMs in federations by merging them. Federations are unions of DBMs and are used to represent non-convex zones. Inclusion checking between DBMs is a limited technique to reduce the size of federations and how to choose some DBMs...... to merge them into a larger one is a combi-natorial problem. We present a number of simple but efficient techniques to avoid searching the combinations while still being able to merge any number of DBMs...

  18. Advances in catalysis

    CERN Document Server

    Gates, Bruce C

    2012-01-01

    Advances in Catalysis fills the gap between the journal papers and the textbooks across the diverse areas of catalysis research. For more than 60 years Advances in Catalysis has been dedicated to recording progress in the field of catalysis and providing the scientific community with comprehensive and authoritative reviews. This series in invaluable to chemical engineers, physical chemists, biochemists, researchers and industrial chemists working in the fields of catalysis and materials chemistry. * In-depth, critical, state-of-the-art reviews * Comprehensive, covers of all as

  19. Photoredox-catalyzed deuteration and tritiation of pharmaceutical compounds.

    Science.gov (United States)

    Loh, Yong Yao; Nagao, Kazunori; Hoover, Andrew J; Hesk, David; Rivera, Nelo R; Colletti, Steven L; Davies, Ian W; MacMillan, David W C

    2017-12-01

    Deuterium- and tritium-labeled pharmaceutical compounds are pivotal diagnostic tools in drug discovery research, providing vital information about the biological fate of drugs and drug metabolites. Herein we demonstrate that a photoredox-mediated hydrogen atom transfer protocol can efficiently and selectively install deuterium (D) and tritium (T) at α-amino sp 3 carbon-hydrogen bonds in a single step, using isotopically labeled water (D 2 O or T 2 O) as the source of hydrogen isotope. In this context, we also report a convenient synthesis of T 2 O from T 2 , providing access to high-specific-activity T 2 O. This protocol has been successfully applied to the high incorporation of deuterium and tritium in 18 drug molecules, which meet the requirements for use in ligand-binding assays and absorption, distribution, metabolism, and excretion studies. Copyright © 2017 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

  20. Merged neutral beams

    Energy Technology Data Exchange (ETDEWEB)

    Osterwalder, Andreas [Ecole Polytechnique Federale de Lausanne (EPFL), Institute for Chemical Sciences and Engineering, Lausanne (Switzerland)

    2015-12-15

    A detailed description of a merged beam apparatus for the study of low energy molecular scattering is given. This review is intended to guide any scientist who plans to construct a similar experiment, and to provide some inspiration in describing the approach we chose to our goal. In our experiment a supersonic expansion of paramagnetic particles is merged with one of polar molecules. A magnetic and an electric multipole guide are used to bend the two beams onto the same axis. We here describe in detail how the apparatus is designed, characterised, and operated. (orig.)

  1. Merged reality for everyone

    OpenAIRE

    Carvalho, Fausto de; Morgado, Leonel

    2017-01-01

    This article addresses some interesting challenges and business opportunities within the promising merged reality ecosystem, which offers the vision of bringing together virtual, augmented and physical realities, seamlessly. The article also links the current status of this field with exploratory research and development work carried out by Altice Labs. Altice Labs info:eu-repo/semantics/publishedVersion

  2. Plan Merging : Experimental results

    NARCIS (Netherlands)

    De Weerdt, M.M.; Van der Krogt, R.P.J.; Zutt, J.

    2003-01-01

    In this paper we discuss the results of a plan merging algorithm. This algorithm coordinates the plans of multiple, autonomous agents, each able to independently find a plan. This algorithm is evaluated using realistic data from a taxi company. We show that when we allow passengers to be a few

  3. Multicatalyst system in asymmetric catalysis

    CERN Document Server

    Zhou, Jian

    2014-01-01

    This book introduces multi-catalyst systems by describing their mechanism and advantages in asymmetric catalysis.  Helps organic chemists perform more efficient catalysis with step-by-step methods  Overviews new concepts and progress for greener and economic catalytic reactions  Covers topics of interest in asymmetric catalysis including bifunctional catalysis, cooperative catalysis, multimetallic catalysis, and novel tandem reactions   Has applications for pharmaceuticals, agrochemicals, materials, and flavour and fragrance

  4. Catalysis seen in action

    NARCIS (Netherlands)

    Tromp, M.

    2015-01-01

    Synchrotron radiation techniques are widely applied in materials research and heterogeneous catalysis. In homogeneous catalysis, its use so far is rather limited despite its high potential. Here, insights in the strengths and limitations of X-ray spectroscopy technique in the field of homogeneous

  5. Monopole catalysis: an overview

    International Nuclear Information System (INIS)

    Dawson, S.

    1983-11-01

    A summary of the talks presented in the topological workshop on monopole catalysis at this conference is given. We place special emphasis on the conservation laws which determine the allowed monopole-fermion interactions and on catalysis as a probe of the structure of a grand unified theory. 11 references

  6. Catalysis of Supramolecular Hydrogelation

    NARCIS (Netherlands)

    Trausel, F.; Versluis, F.; Maity, C.; Poolman, J.M.; Lovrak, M.; van Esch, J.H.; Eelkema, R.

    2016-01-01

    ConspectusOne often thinks of catalysts as chemical tools to accelerate a reaction or to have a reaction run under more benign conditions. As such, catalysis has a role to play in the chemical industry and in lab scale synthesis that is not to be underestimated. Still, the role of catalysis in

  7. Photoredox Generated Radicals in Csp2-Csp3 Bond Construction

    Science.gov (United States)

    Primer, David Neal

    The routine application of Csp3-hybridized nucleophiles in cross-coupling has been an ongoing pursuit in the agrochemical, pharmaceutical, and materials science industries for over 40 years. Unfortunately, despite numerous attempts to circumvent the problems associated with alkyl nucleophiles, application of these reagents in transition metal-catalyzed C-C bond-forming reactions has remained largely restricted. In recent years, many chemists have noted the lack of reliable, turnkey reactions that exist for the installation of Csp3-hybridized centers--reactions that would be useful for delivering molecules with enhanced three-dimensional topology and altered chemical properties. As such, a general method for alkyl nucleophile activation in cross-coupling would offer access to a host of compounds inaccessible by other means. From a mechanistic standpoint, the continued failure of alkylmetallics is inherent to the high energy intermediates associated with a traditional transmetalation. To overcome this problem, we have pioneered an alternate, single-electron pathway involving 1) initial oxidation of an alkylmetallic reagent, 2) oxidative alkyl radical capture at a metal center, and 3) subsequent reduction of the metal center to return its initial oxidation state. This series of steps constitutes a formal transmetalation that avoids the energy-demanding steps that plague a traditional anionic approach. Under this enabling paradigm, a host of alkyl precursors (alkyl-trifluoroborates and -silicates) have been generally used in cross-coupling for the first time. In summary, the synergistic use of an Ir photoredox catalyst and a Ni cross-coupling catalyst to mediate the cross-coupling of (hetero)aryl bromides with diverse alkyl radical precursors will be discussed. Methods for coupling various trifluoroborate classes (alpha-alkoxy, alpha-trifluoromethyl, secondary and tertiary alkyl) will be covered, focusing on their complementarity to traditional protocols. Finally, a

  8. Enantioselective Direct α-Amination of Aldehydes via a Photoredox Mechanism: A Strategy for Asymmetric Amine Fragment Coupling

    OpenAIRE

    Cecere, Giuseppe; Koenig, Christian M.; Alleva, Jennifer L.; MacMillan, David W. C.

    2013-01-01

    The direct, asymmetric α-amination of aldehydes has been accomplished via a combination of photoredox and organocatalysis. Photon-generated, nitrogen-centered radicals undergo enantioselective α-addition to catalytically formed chiral enamines to directly produce stable α-amino aldehyde adducts bearing synthetically useful amine substitution patterns. Incorporation of a photolabile group on the amine precursor obviates the need to employ a photoredox catalyst in this transformation. Important...

  9. Horizons in catalysis

    Energy Technology Data Exchange (ETDEWEB)

    Idol, J D

    1979-04-21

    A discussion covers a brief historical review of industrial catalysis; a survey of major present-day catalytic processes in the petroleum and petrochemical industries; the outlook for the industrial catalyst applications in coal liquefaction, conversion of coal liquids, shale oil, and other synthetic crude sources for transportation fuels, and synthesis gas-based processes; some important directions for future developments, including phase transfer catalysis, photocatalysis, and advanced techniques for catalyst studies; and the need for closer industry-university and industry-government cooperation in the field of catalysis.

  10. Surface and nanomolecular catalysis

    CERN Document Server

    Richards, Ryan

    2006-01-01

    Using new instrumentation and experimental techniques that allow scientists to observe chemical reactions and molecular properties at the nanoscale, the authors of Surface and Nanomolecular Catalysis reveal new insights into the surface chemistry of catalysts and the reaction mechanisms that actually occur at a molecular level during catalysis. While each chapter contains the necessary background and explanations to stand alone, the diverse collection of chapters shows how developments from various fields each contributed to our current understanding of nanomolecular catalysis as a whole. The

  11. Molecular water oxidation catalysis

    CERN Document Server

    Llobet, Antoni

    2014-01-01

    Photocatalytic water splitting is a promising strategy for capturing energy from the sun by coupling light harvesting and the oxidation of water, in order to create clean hydrogen fuel. Thus a deep knowledge of the water oxidation catalysis field is essential to be able to come up with useful energy conversion devices based on sunlight and water splitting. Molecular Water Oxidation Catalysis: A Key Topic for New Sustainable Energy Conversion Schemes presents a comprehensive and state-of-the-art overview of water oxidation catalysis in homogeneous phase, describing in detail the most importan

  12. Why healthcare providers merge.

    Science.gov (United States)

    Postma, Jeroen; Roos, Anne-Fleur

    2016-04-01

    In many OECD countries, healthcare sectors have become increasingly concentrated as a result of mergers. However, detailed empirical insight into why healthcare providers merge is lacking. Also, we know little about the influence of national healthcare policies on mergers. We fill this gap in the literature by conducting a survey study on mergers among 848 Dutch healthcare executives, of which 35% responded (resulting in a study sample of 239 executives). A total of 65% of the respondents was involved in at least one merger between 2005 and 2012. During this period, Dutch healthcare providers faced a number of policy changes, including increasing competition, more pressure from purchasers, growing financial risks, de-institutionalisation of long-term care and decentralisation of healthcare services to municipalities. Our empirical study shows that healthcare providers predominantly merge to improve the provision of healthcare services and to strengthen their market position. Also efficiency and financial reasons are important drivers of merger activity in healthcare. We find that motives for merger are related to changes in health policies, in particular to the increasing pressure from competitors, insurers and municipalities.

  13. Visible Light Organic Photoredox-Catalyzed C-H Alkoxylation of Imidazopyridine with Alcohol.

    Science.gov (United States)

    Kibriya, Golam; Samanta, Sadhanendu; Jana, Sourav; Mondal, Susmita; Hajra, Alakananda

    2017-12-15

    The visible light-mediated C-3 alkoxylation of imidazopyridines with alcohols has been achieved using rose bengal as an organic photoredox catalyst at room temperature. Widely abundant air acts as the terminal oxidant that avoids the use of a stoichiometric amount of peroxo compounds. A wide range of functional groups could be tolerated under the reaction conditions to produce C(sp 2 )-H alkoxylated products in high yields.

  14. Photoredox-Catalyzed Ketyl–Olefin Coupling for the Synthesis of Substituted Chromanols

    KAUST Repository

    Fava, Eleonora

    2016-07-21

    A visible light photoredox-catalyzed aldehyde olefin cyclization is reported. The method represents a formal hydroacylation of alkenes and alkynes and provides chromanol derivatives in good yields. The protocol takes advantage of the double role played by trialkylamines (NR3) which act as (i) electron donors for reducing the catalyst and (ii) proton donors to activate the substrate via a proton-coupled electron transfer. © 2016 American Chemical Society.

  15. Photoredox-Catalyzed Ketyl–Olefin Coupling for the Synthesis of Substituted Chromanols

    KAUST Repository

    Fava, Eleonora; Nakajima, Masaki; Nguyen, Anh L. P.; Rueping, Magnus

    2016-01-01

    A visible light photoredox-catalyzed aldehyde olefin cyclization is reported. The method represents a formal hydroacylation of alkenes and alkynes and provides chromanol derivatives in good yields. The protocol takes advantage of the double role played by trialkylamines (NR3) which act as (i) electron donors for reducing the catalyst and (ii) proton donors to activate the substrate via a proton-coupled electron transfer. © 2016 American Chemical Society.

  16. Catalysis seen in action.

    Science.gov (United States)

    Tromp, Moniek

    2015-03-06

    Synchrotron radiation techniques are widely applied in materials research and heterogeneous catalysis. In homogeneous catalysis, its use so far is rather limited despite its high potential. Here, insights in the strengths and limitations of X-ray spectroscopy technique in the field of homogeneous catalysis are given, including new technique developments. A relevant homogeneous catalyst, used in the industrially important selective oligomerization of ethene, is taken as a worked-out example. Emphasis is placed on time-resolved operando X-ray absorption spectroscopy with outlooks to novel high energy resolution and emission techniques. All experiments described have been or can be done at the Diamond Light Source Ltd (Didcot, UK). © 2015 The Author(s) Published by the Royal Society. All rights reserved.

  17. Concepts in catalysis

    International Nuclear Information System (INIS)

    Boudart, M.

    1992-01-01

    This paper reports on concept in catalysis which are very important in heterogeneous catalysis, even today, when in spite of surface science, the complexity of events at a real catalytic surface is still evading the understanding necessary for design. In this paper the authors will attempt to give an update on evolving concepts in heterogeneous catalysis. The topics include: counting active centers on metal surfaces; the notion of turnover frequency for a catalytic cycle; the concept of structure (in) sensitive reactions; the ensemble (geometric) vs. The ligand (electronic) effect following Sachtler's school; the idea of a rate determining step and of a most abundant reactive intermediate; the effect of surface non-uniformity on catalytic kinetics; what makes catalytic cycles turnover

  18. Catalysis induced by radiations

    International Nuclear Information System (INIS)

    Jimenez B, J.; Gonzalez J, J. C.

    2010-01-01

    In Mexico is generated a great quantity of residuals considered as dangerous, for its capacity of corrosion, reactivity, toxicity to the environment, inflammability and biological-infectious potential. It is important to mention that the toxic compounds cannot be discharged to the sewerage systems and much less to the receiving bodies of water. The usual treatment that receives the dangerous residuals is the incineration and the bordering. The incineration is an efficient form of treating the residuals, but it can be dioxins source and benzofurans, being the phenol and chloro phenol the precursors of these compounds. At the present time the radiolytic degradation of organic compounds has been broadly studied, especially the 4-chloro phenol and of same form the photo catalysis of organic compounds. However the combination of both processes, called radio catalysis is barely reported. In this work the results of the experiments realized for to degrade the 4-chloro phenol by means of radio catalysis are reported. (Author)

  19. Catalysis for alternative energy generation

    CERN Document Server

    2012-01-01

    Summarizes recent problems in using catalysts in alternative energy generation and proposes novel solutions  Reconsiders the role of catalysis in alternative energy generation  Contributors include catalysis and alternative energy experts from across the globe

  20. Editorial: Nanoscience makes catalysis greener

    KAUST Repository

    Polshettiwar, Vivek; Basset, Jean-Marie; Astruc, Didier

    2012-01-01

    Green chemistry by nanocatalysis: Catalysis is a strategic field of science because it involves new ways of meeting energy and sustainability challenges. The concept of green chemistry, which makes the science of catalysis even more creative, has

  1. Isotopes in heterogeneous catalysis

    CERN Document Server

    Hargreaves, Justin SJ

    2006-01-01

    The purpose of this book is to review the current, state-of-the-art application of isotopic methods to the field of heterogeneous catalysis. Isotopic studies are arguably the ultimate technique in in situ methods for heterogeneous catalysis. In this review volume, chapters have been contributed by experts in the field and the coverage includes both the application of specific isotopes - Deuterium, Tritium, Carbon-14, Sulfur-35 and Oxygen-18 - as well as isotopic techniques - determination of surface mobility, steady state transient isotope kinetic analysis, and positron emission profiling.

  2. A tangent subsolar merging line

    International Nuclear Information System (INIS)

    Crooker, N.U.; Siscoe, G.L.; Toffoletto, F.R.

    1990-01-01

    The authors describe a global magnetospheric model with a single subsolar merging line whose position is determined neither locally by the relative orientations and strengths of the merging fields nor globally by the orientation of a separator line--the governing parameters of most previous models--but by the condition of tangential contact between the external field and the magnetopause. As in previous models, the tilt of the merging line varies with IMF orientation, but here it also depends upon the ratio of Earth's magnetic flux that leaks out of the magnetopause to IMF flux that penetrates in. In the limiting case treated by Alekseyev and Belen'kaya, with no leakage of Earth's field and total IMF penetration, the merging line forms a great circle around a spherical magnetosphere where undeviated IMF lines lie tangent to its surface. This tangent merging line lies perpendicular to the IMF. They extend their work to the case of finite leakage and partial penetration, which distort the IMF into a draped pattern, thus changing the locus of tangency to the sphere. In the special case where the penetrating IMF flux is balanced by an equal amount of Earth flux leakage, the tangent merging line bisects the angle between the IMF and Earth's northward subsolar field. This result is identical to the local merging line model result for merging fields with equal magnitude. Here a global flux balance condition replaces the local equal magnitude condition

  3. Dayside merging and cusp geometry

    International Nuclear Information System (INIS)

    Crooker, N.U.

    1979-01-01

    Geometrical considerations are presented to show that dayside magnetic merging when constrained to act only where the fields are antiparallel results in lines of merging that converge at the polar cusps. An important consequence of this geometry is that no accelerated flows are predicted across the dayside magnetopause. Acceleration owing to merging acts in opposition to the magnetosheath flow at the merging point and produces the variably directed, slower-than-magnetosheath flows observed in the entry layer. Another consequence of the merging geometry is that much of the time closed field lines constitute the subsolar region of the magnetopause. The manner in which the polar cap convection patterns predicted by the proposed geometry change as the interplanetary field is rotated through 360 0 provides a unifying description of how the observed single circular vortex and the crescent-shaped double vortex patterns mutually evolve under the influence of a single operating principle

  4. ESO's Two Observatories Merge

    Science.gov (United States)

    2005-02-01

    On February 1, 2005, the European Southern Observatory (ESO) has merged its two observatories, La Silla and Paranal, into one. This move will help Europe's prime organisation for astronomy to better manage its many and diverse projects by deploying available resources more efficiently where and when they are needed. The merged observatory will be known as the La Silla Paranal Observatory. Catherine Cesarsky, ESO's Director General, comments the new development: "The merging, which was planned during the past year with the deep involvement of all the staff, has created unified maintenance and engineering (including software, mechanics, electronics and optics) departments across the two sites, further increasing the already very high efficiency of our telescopes. It is my great pleasure to commend the excellent work of Jorge Melnick, former director of the La Silla Observatory, and of Roberto Gilmozzi, the director of Paranal." ESO's headquarters are located in Garching, in the vicinity of Munich (Bavaria, Germany), and this intergovernmental organisation has established itself as a world-leader in astronomy. Created in 1962, ESO is now supported by eleven member states (Belgium, Denmark, Finland, France, Germany, Italy, The Netherlands, Portugal, Sweden, Switzerland, and the United Kingdom). It operates major telescopes on two remote sites, all located in Chile: La Silla, about 600 km north of Santiago and at an altitude of 2400m; Paranal, a 2600m high mountain in the Atacama Desert 120 km south of the coastal city of Antofagasta. Most recently, ESO has started the construction of an observatory at Chajnantor, a 5000m high site, also in the Atacama Desert. La Silla, north of the town of La Serena, has been the bastion of the organization's facilities since 1964. It is the site of two of the most productive 4-m class telescopes in the world, the New Technology Telescope (NTT) - the first major telescope equipped with active optics - and the 3.6-m, which hosts HARPS

  5. Distributed Merge Trees

    Energy Technology Data Exchange (ETDEWEB)

    Morozov, Dmitriy; Weber, Gunther

    2013-01-08

    Improved simulations and sensors are producing datasets whose increasing complexity exhausts our ability to visualize and comprehend them directly. To cope with this problem, we can detect and extract significant features in the data and use them as the basis for subsequent analysis. Topological methods are valuable in this context because they provide robust and general feature definitions. As the growth of serial computational power has stalled, data analysis is becoming increasingly dependent on massively parallel machines. To satisfy the computational demand created by complex datasets, algorithms need to effectively utilize these computer architectures. The main strength of topological methods, their emphasis on global information, turns into an obstacle during parallelization. We present two approaches to alleviate this problem. We develop a distributed representation of the merge tree that avoids computing the global tree on a single processor and lets us parallelize subsequent queries. To account for the increasing number of cores per processor, we develop a new data structure that lets us take advantage of multiple shared-memory cores to parallelize the work on a single node. Finally, we present experiments that illustrate the strengths of our approach as well as help identify future challenges.

  6. Pollution Control by Catalysis

    DEFF Research Database (Denmark)

    Eriksen, Kim Michael; Fehrmann, Rasmus

    1998-01-01

    The report summarises the results of two years of collaboration supported by INTAS between Department of Chemistry,DTU,DK , IUSTI,Universite de Provence,FR, ICE/HT University 6of Patras,GR, and Boreskov Institute of Catalysis,RU.The project has been concerned with mechanistic studies of deNOx and...

  7. Preface: Catalysis Today

    DEFF Research Database (Denmark)

    Li, Yongdan

    2016-01-01

    This special issue of Catalysis Today with the theme “Sustain-able Energy” results from a great success of the session “Catalytic Technologies Accelerating the Establishment of Sustainable and Clean Energy”, one of the two sessions of the 1st International Symposium on Catalytic Science and Techn...

  8. Triadic split-merge sampler

    Science.gov (United States)

    van Rossum, Anne C.; Lin, Hai Xiang; Dubbeldam, Johan; van der Herik, H. Jaap

    2018-04-01

    In machine vision typical heuristic methods to extract parameterized objects out of raw data points are the Hough transform and RANSAC. Bayesian models carry the promise to optimally extract such parameterized objects given a correct definition of the model and the type of noise at hand. A category of solvers for Bayesian models are Markov chain Monte Carlo methods. Naive implementations of MCMC methods suffer from slow convergence in machine vision due to the complexity of the parameter space. Towards this blocked Gibbs and split-merge samplers have been developed that assign multiple data points to clusters at once. In this paper we introduce a new split-merge sampler, the triadic split-merge sampler, that perform steps between two and three randomly chosen clusters. This has two advantages. First, it reduces the asymmetry between the split and merge steps. Second, it is able to propose a new cluster that is composed out of data points from two different clusters. Both advantages speed up convergence which we demonstrate on a line extraction problem. We show that the triadic split-merge sampler outperforms the conventional split-merge sampler. Although this new MCMC sampler is demonstrated in this machine vision context, its application extend to the very general domain of statistical inference.

  9. Advances in catalysis

    International Nuclear Information System (INIS)

    Eley, D.D.; Pine, H.; Weisz, P.B.

    1989-01-01

    This book reports on the current state of knowledge concerning structure and catalysis of metals and metal oxide particles, old and new. It addresses the basic and broad problems of what the catalytically relevant surface structures of metals are, where we stand in techniques capable of attacking this problem, and what the current state of knowledge is. The focus is on long-standing, important, and central problem of general investigative methodology and strategy: the pressure gap is created by the fact that the best techniques of surface analysis require high-vacuum conditions, while useful catalysis is confined to conditions of near ambient or higher pressures. The authors review the basic question of the influence of particle size on catalytic behavior of metal particles which involves questions of the basic sciences as much as practical considerations of catalyst design and use. They discuss preparatory techniques, analytical technology, and methods of characterization of these materials

  10. Solid Base Catalysis

    CERN Document Server

    Ono, Yoshio

    2011-01-01

    The importance of solid base catalysts has come to be recognized for their environmentally benign qualities, and much significant progress has been made over the past two decades in catalytic materials and solid base-catalyzed reactions. The book is focused on the solid base. Because of the advantages over liquid bases, the use of solid base catalysts in organic synthesis is expanding. Solid bases are easier to dispose than liquid bases, separation and recovery of products, catalysts and solvents are less difficult, and they are non-corrosive. Furthermore, base-catalyzed reactions can be performed without using solvents and even in the gas phase, opening up more possibilities for discovering novel reaction systems. Using numerous examples, the present volume describes the remarkable role solid base catalysis can play, given the ever increasing worldwide importance of "green" chemistry. The reader will obtain an overall view of solid base catalysis and gain insight into the versatility of the reactions to whic...

  11. Metallic nanosystems in catalysis

    International Nuclear Information System (INIS)

    Bukhtiyarov, Valerii I; Slin'ko, Mikhail G

    2001-01-01

    The reactivities of metallic nanosystems in catalytic processes are considered. The activities of nanoparticles in catalysis are due to their unique microstructures, electronic properties and high specific surfaces of the active centres. The problems of increasing the selectivities of catalytic processes are discussed using several nanosystems as examples. The mutual effects of components of bimetallic nanoparticles are discussed. The prospects for theoretical and experimental investigations into catalytic nanosystems and the construction of industrial catalysts based on them are evaluated. The bibliography includes 207 references.

  12. CATALYSIS OF CHEMICAL PROCESSES: PARTICULAR ...

    African Journals Online (AJOL)

    IICBA01

    secondary/high schools and universities, the inhibition of the chemical reactions is frequently ... As a result, the lesson catalysis is frequently included in chemistry education curricula at ... Misinterpretations in teaching and perception of catalysis ... profile is shown as a dependence of energy on reaction progress, without ...

  13. Spectroscopy in catalysis : an introduction

    NARCIS (Netherlands)

    Niemantsverdriet, J.W.

    2007-01-01

    Spectroscopy in Catalysis is an introduction to the most important analytical techniques that are nowadays used in catalysis and in catalytic surface chemistry. The aim of the book is to give the reader a feeling for the type of information that characterization techniques provide about questions

  14. Correlation order, merging and diversification

    NARCIS (Netherlands)

    Dhaene, J.; Denuit, M.; Vanduffel, S.

    2009-01-01

    We investigate the influence of the dependence between random losses on the shortfall and on the diversification benefit that arises from merging these losses. We prove that increasing the dependence between losses, expressed in terms of correlation order, has an increasing effect on the shortfall,

  15. Practical Engineering Aspects of Catalysis in Microreactors

    Czech Academy of Sciences Publication Activity Database

    Křišťál, Jiří; Stavárek, Petr; Vajglová, Zuzana; Vondráčková, Magdalena; Pavlorková, Jana; Jiřičný, Vladimír

    2015-01-01

    Roč. 41, č. 12 (2015), s. 9357-9371 ISSN 0922-6168. [Pannonian Symposium on Catalysis /12./. Castle Trest, 16.09.2014-20.09.2014] Institutional support: RVO:67985858 Keywords : heterogeneous catalysis * homogeneous catalysis * photo catalysis Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 1.833, year: 2015

  16. Photoredox-Catalyzed Stereoselective Conversion of Alkynes into Tetrasubstituted Trifluoromethylated Alkenes.

    Science.gov (United States)

    Tomita, Ren; Koike, Takashi; Akita, Munetaka

    2015-10-26

    A regio- and stereoselective synthesis of trifluoromethylated alkenes bearing four different substituents has been developed. Stereocontrolled sulfonyloxytrifluoromethylation of unsymmetric internal alkynes with an electrophilic CF3 reagent, namely the triflate salt of the Yagupol'skii-Umemoto reagent, in the presence of an Ir photoredox catalyst under visible-light irradiation afforded trifluoromethylalkenyl triflates with well-predictable stereochemistry resulting from anti addition of the trifluoromethyl and triflate groups. Subsequent palladium-catalyzed cross-couplings led to tetrasubstituted trifluoromethylated alkenes in a highly stereoselective manner. The present method is the first example of a facile one-pot synthesis of tetrasubstituted trifluoromethylated alkenes from simple alkynes. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Magnetic catalysis and inverse magnetic catalysis in QCD

    International Nuclear Information System (INIS)

    Mueller, N.

    2015-01-01

    We investigate the effects of strong magnetic fields on the QCD phase structure at vanishing density by solving the gluon and quark gap equations. The chiral crossover temperature as well as the chiral condensate is computed. For asymptotically large magnetic fields we find magnetic catalysis, while we find inverse magnetic catalysis for intermediate magnetic fields. Moreover, for large magnetic fields the chiral phase transition for massless quarks turns into a crossover. The underlying mechanisms are then investigated analytically within a few simplifications of the full numerical analysis. We find that a combination of gluon screening effects and the weakening of the strong coupling is responsible for the phenomenon of inverse catalysis seen in lattice studies. In turn, the magnetic catalysis at large magnetic field is already indicated by simple arguments based on dimensionality. (author)

  18. Spheromak Merging Experiments on SSX

    Science.gov (United States)

    Brown, M. R.; Kornack, T. W.; Sollins, P. K.; Luh, W. J.

    1997-11-01

    Spheromak merging experiments are underway at the Swarthmore Spheromak Experiment (SSX) at Swarthmore College. The spheromaks are formed by identical magnetized plasma guns and equilibrium is established in close fitting 0.5 m diameter copper flux conservers. Partial merging is achieved through openings in the back wall. We observe the formation of a reconnection boundary layer at the interface of the two spheromaks using a linear probe array. The characteristic scale of the flux reversal is about 1 cm (consistent with the diffusion scale δ_diff, the ion Larmor radius ρi and the ion inertial length c/ω_pi). Movies of the formation and evolution of the layer will be presented. Correlations between reconnection events and pulses of soft x-rays and energetic particles will be presented if available. Plans for 2D and 3D imaging of the layer will also be discussed.

  19. Modeling cooperative driving behavior in freeway merges.

    Science.gov (United States)

    2011-11-01

    Merging locations are major sources of freeway bottlenecks and are therefore important for freeway operations analysis. Microscopic simulation tools have been successfully used to analyze merging bottlenecks and to design optimum geometric configurat...

  20. Automatic generation of data merging program codes.

    OpenAIRE

    Hyensook, Kim; Oussena, Samia; Zhang, Ying; Clark, Tony

    2010-01-01

    Data merging is an essential part of ETL (Extract-Transform-Load) processes to build a data warehouse system. To avoid rewheeling merging techniques, we propose a Data Merging Meta-model (DMM) and its transformation into executable program codes in the manner of model driven engineering. DMM allows defining relationships of different model entities and their merging types in conceptual level. Our formalized transformation described using ATL (ATLAS Transformation Language) enables automatic g...

  1. Spectroscopy in catalysis : an introduction

    NARCIS (Netherlands)

    Niemantsverdriet, J.W.

    2000-01-01

    Spectroscopy in Catalysis describes the most important modern analytical techniques used to investigate catalytic surfaces. These include electron spectroscopy (XPS, UPS, AES, EELS), ion spectroscopy (SIMS, SNMS, RBS, LEIS), vibrational spectroscopy (infrared, Raman, EELS), temperature-programmed

  2. Editorial: Nanoscience makes catalysis greener

    KAUST Repository

    Polshettiwar, Vivek

    2012-01-09

    Green chemistry by nanocatalysis: Catalysis is a strategic field of science because it involves new ways of meeting energy and sustainability challenges. The concept of green chemistry, which makes the science of catalysis even more creative, has become an integral part of sustainability. This special issue is at the interface of green chemistry and nanocatalysis, and features excellent background articles as well as the latest research results. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Molecular ingredients of heterogeneous catalysis

    International Nuclear Information System (INIS)

    Somorjai, G.A.

    1982-06-01

    The purpose of this paper is to present a review and status report to those in theoretical chemistry of the rapidly developing surface science of heterogeneous catalysis. The art of catalysis is developing into science. This profound change provides one with opportunities not only to understand the molecular ingredients of important catalytic systems but also to develop new and improved catalyst. The participation of theorists to find answers to important questions is sorely needed for the sound development of the field. It is the authors hope that some of the outstanding problems of heterogeneous catalysis that are identified in this paper will be investigated. For this purpose the paper is divided into several sections. The brief Introduction to the methodology and recent results of the surface science of heterogeneous catalysis is followed by a review of the concepts of heterogeneous catalysis. Then, the experimental results that identified the three molecular ingredients of catalysis, structure, carbonaceous deposit and the oxidation state of surface atoms are described. Each section is closed with a summary and a list of problems that require theoretical and experimental scrutiny. Finally attempts to build new catalyst systems and the theoretical and experimental problems that appeared in the course of this research are described

  4. Molecular ingredients of heterogeneous catalysis

    Energy Technology Data Exchange (ETDEWEB)

    Somorjai, G.A.

    1982-06-01

    The purpose of this paper is to present a review and status report to those in theoretical chemistry of the rapidly developing surface science of heterogeneous catalysis. The art of catalysis is developing into science. This profound change provides one with opportunities not only to understand the molecular ingredients of important catalytic systems but also to develop new and improved catalyst. The participation of theorists to find answers to important questions is sorely needed for the sound development of the field. It is the authors hope that some of the outstanding problems of heterogeneous catalysis that are identified in this paper will be investigated. For this purpose the paper is divided into several sections. The brief Introduction to the methodology and recent results of the surface science of heterogeneous catalysis is followed by a review of the concepts of heterogeneous catalysis. Then, the experimental results that identified the three molecular ingredients of catalysis, structure, carbonaceous deposit and the oxidation state of surface atoms are described. Each section is closed with a summary and a list of problems that require theoretical and experimental scrutiny. Finally attempts to build new catalyst systems and the theoretical and experimental problems that appeared in the course of this research are described.

  5. Enhanced Micellar Catalysis LDRD.

    Energy Technology Data Exchange (ETDEWEB)

    Betty, Rita G.; Tucker, Mark D; Taggart, Gretchen; Kinnan, Mark K.; Glen, Crystal Chanea; Rivera, Danielle; Sanchez, Andres; Alam, Todd Michael

    2012-12-01

    The primary goals of the Enhanced Micellar Catalysis project were to gain an understanding of the micellar environment of DF-200, or similar liquid CBW surfactant-based decontaminants, as well as characterize the aerosolized DF-200 droplet distribution and droplet chemistry under baseline ITW rotary atomization conditions. Micellar characterization of limited surfactant solutions was performed externally through the collection and measurement of Small Angle X-Ray Scattering (SAXS) images and Cryo-Transmission Electron Microscopy (cryo-TEM) images. Micellar characterization was performed externally at the University of Minnesotas Characterization Facility Center, and at the Argonne National Laboratory Advanced Photon Source facility. A micellar diffusion study was conducted internally at Sandia to measure diffusion constants of surfactants over a concentration range, to estimate the effective micelle diameter, to determine the impact of individual components to the micellar environment in solution, and the impact of combined components to surfactant phase behavior. Aerosolized DF-200 sprays were characterized for particle size and distribution and limited chemical composition. Evaporation rates of aerosolized DF-200 sprays were estimated under a set of baseline ITW nozzle test system parameters.

  6. Operando research in heterogeneous catalysis

    CERN Document Server

    Groot, Irene

    2017-01-01

    This book is devoted to the emerging field of techniques for visualizing atomic-scale properties of active catalysts under actual working conditions, i.e. high gas pressures and high temperatures. It explains how to understand these observations in terms of the surface structures and dynamics and their detailed interplay with the gas phase. This provides an important new link between fundamental surface physics and chemistry, and applied catalysis. The book explains the motivation and the necessity of operando studies, and positions these with respect to the more traditional low-pressure investigations on the one hand and the reality of industrial catalysis on the other. The last decade has witnessed a rapid development of new experimental and theoretical tools for operando studies of heterogeneous catalysis. The book has a strong emphasis on the new techniques and illustrates how the challenges introduced by the harsh, operando conditions are faced for each of these new tools. Therefore, one can also read th...

  7. Green chemistry by nano-catalysis

    KAUST Repository

    Polshettiwar, Vivek; Varma, Rajender S.

    2010-01-01

    the homogeneous catalysts. This review focuses on the use of nano-catalysis for green chemistry development including the strategy of using microwave heating with nano-catalysis in benign aqueous reaction media which offers an extraordinary synergistic effect

  8. Is merging and acquisition profitable?

    International Nuclear Information System (INIS)

    Skjeret, Frode; Soergard, Lars

    2002-01-01

    This report deals with mergers and acquisitions in the electricity sector in Norway. The background is the fact that the profitability of these activities proves to be low. In buying, it is typically the selling shareholder who profits from the transaction, while the buying company does not really earn much. This result appears to be a robust result both in different countries, between sectors and independent of methodology. The report provides theoretical justification for merging and buying up and empirical evaluations of the effects of company integration. It is asserted that what can be learned in general from the literature may also occur in the European power sector. Furthermore, the report discusses the challenges faced by the companies if they want to expand through mergers and acquisitions

  9. Positron studies in catalysis research

    International Nuclear Information System (INIS)

    1994-01-01

    During the past eight months, the authors have made progress in several areas relevant to the eventual use of positron techniques in catalysis research. They have come closer to the completion of their positron microscope, and at the same time have performed several studies in their non-microscopic positron spectrometer which should ultimately be applicable to catalysis. The current status of the efforts in each of these areas is summarized in the following sections: Construction of the positron microscope (optical element construction, data collection software, and electronic sub-assemblies); Doppler broadening spectroscopy of metal silicide; Positron lifetime spectroscopy of glassy polymers; and Positron lifetime measurements of pore-sizes in zeolites

  10. Catalysis and sustainable (green) chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Centi, Gabriele; Perathoner, Siglinda [Dipartimento di Chimica Industriale ed Ingegneria dei Materiali, University of Messina, Salita Sperone 31, 98166 Messina (Italy)

    2003-01-15

    Catalysis is a key technology to achieve the objectives of sustainable (green) chemistry. After introducing the concepts of sustainable (green) chemistry and a brief assessment of new sustainable chemical technologies, the relationship between catalysis and sustainable (green) chemistry is discussed and illustrated via an analysis of some selected and relevant examples. Emphasis is also given to the concept of catalytic technologies for scaling-down chemical processes, in order to develop sustainable production processes which reduce the impact on the environment to an acceptable level that allows self-depuration processes of the living environment.

  11. Morphology of magnetic merging at the magnetopause

    International Nuclear Information System (INIS)

    Crooker, N.U.

    1990-01-01

    To illustrate the basic features of magnetospheric topology, the development of a global model is traced from the superposition of dipole and uniform fields to the effects of adding, in turn, diffusion regions, surface currents, and a magnetic field component normal to the magnetopause. The subsolar, antiparallel, tearing, and patchy merging geometries proposed in the past all emerge under various conditions, but models tht deduce merging geometry from global boundary conditions are lacking. An exception is a model in which the external field merges wherever it falls tangent to the magnetopause. The result is a subsolar merging line that has all the characteristics of early sketches based on local arguments. Magnetosheath plasma beta affects magnetospheric topology and, consequently, merging geometry. Low, high, and variable beta favor subsolar, tearing, and patchy merging, respectively. Proposed flux transfer event models of burst reconnection from a single merging line, flux ropes from multiple merging lines, and flux tube elbows from patches can also be categorized by plasma beta in the same respective order. The topological modeling reviewed here may prove to be most useful for interpreting merging results from MHD simulations. (author)

  12. Merging By Decentralized Eventual Consistency Algorithms

    Directory of Open Access Journals (Sweden)

    Ahmed-Nacer Mehdi

    2015-12-01

    Full Text Available Merging mechanism is an essential operation for version control systems. When each member of collaborative development works on an individual copy of the project, software merging allows to reconcile modifications made concurrently as well as managing software change through branching. The collaborative system is in charge to propose a merge result that includes user’s modifications. Theusers now have to check and adapt this result. The adaptation should be as effort-less as possible, otherwise, the users may get frustrated and will quit the collaboration. This paper aims to reduce the conflicts during the collaboration and im prove the productivity. It has three objectives: study the users’ behavior during the collaboration, evaluate the quality of textual merging results produced by specific algorithms and propose a solution to improve the r esult quality produced by the default merge tool of distributed version control systems. Through a study of eight open-source repositories totaling more than 3 million lines of code, we observe the behavior of the concurrent modifications during t he merge p rocedure. We i dentified when th e ex isting merge techniques under-perform, and we propose solutions to improve the quality of the merge. We finally compare with the traditional merge tool through a large corpus of collaborative editing.

  13. EMSL and Institute for Integrated Catalysis (IIC) Catalysis Workshop

    Energy Technology Data Exchange (ETDEWEB)

    Campbell, Charles T.; Datye, Abhaya K.; Henkelman, Graeme A.; Lobo, Raul F.; Schneider, William F.; Spicer, Leonard D.; Tysoe, Wilfred T.; Vohs, John M.; Baer, Donald R.; Hoyt, David W.; Thevuthasan, Suntharampillai; Mueller, Karl T.; Wang, Chong M.; Washton, Nancy M.; Lyubinetsky, Igor; Teller, Raymond G.; Andersen, Amity; Govind, Niranjan; Kowalski, Karol; Kabius, Bernd C.; Wang, Hongfei; Campbell, Allison A.; Shelton, William A.; Bylaska, Eric J.; Peden, Charles HF; Wang, Yong; King, David L.; Henderson, Michael A.; Rousseau, Roger J.; Szanyi, Janos; Dohnalek, Zdenek; Mei, Donghai; Garrett, Bruce C.; Ray, Douglas; Futrell, Jean H.; Laskin, Julia; DuBois, Daniel L.; Kuprat, Laura R.; Plata, Charity

    2011-05-24

    Within the context of significantly accelerating scientific progress in research areas that address important societal problems, a workshop was held in November 2010 at EMSL to identify specific and topically important areas of research and capability needs in catalysis-related science.

  14. Cyclopalladated complexes in enantioselective catalysis

    Energy Technology Data Exchange (ETDEWEB)

    Dunina, Valeria V; Gorunova, Olga N; Zykov, P A; Kochetkov, Konstantin A

    2011-01-31

    The results of the use of optically active palladacycles in enantioselective catalysis of [3,3]-sigmatropic rearrangements, aldol condensation, the Michael reaction and cross-coupling are analyzed. Reactions with allylic substrates or reagents and some other transformations are considered.

  15. Catalysis in Molten Ionic Media

    DEFF Research Database (Denmark)

    Boghosian, Soghomon; Fehrmann, Rasmus

    2013-01-01

    This chapter deals with catalysis in molten salts and ionic liquids, which are introduced and reviewed briefly, while an in-depth review of the oxidation catalyst used for the manufacturing of sulfuric acid and cleaning of flue gas from electrical power plants is the main topic of the chapter...

  16. The 2003 Merged Model for Vietnam

    DEFF Research Database (Denmark)

    Jensen, Henning Tarp; Tarp, Finn

    This monograph documents the 2003 Merged Model for Vietnam. The initialization and calibration of the model is based on a financial 2003 SAM framework and an auxiliary 2002-3 data set. The recursive nature of the solution of the Merged Model is discussed with reference to the four main sectors...

  17. BNFL/Siemens to merge?

    International Nuclear Information System (INIS)

    Anon.

    1997-01-01

    Negotiations are being conducted on the creation of a joint venture between British Nuclear Fuels Limited (BNFL) and the German company Siemens. The venture would merge Siemens' nuclear fuel, engineering and construction services businesses with BNFL's Magnox and AGR fuel fabrication business which is based at Springfields in Lancashire. It would incorporate Siemens' share of Nuclear Power International, a joint venture with the French company Framatone which is developing the European Pressurised Water Reactor project, and its US subsidiary Siemens' Power Corp. BNFL's mixed oxide (MOX) fuel fabrication business, its stake in the Dutch-German-UK uranium enrichment company Urenco and its nuclear waste reprocessing business would not be involved. There is already speculation that Siemens' greater input will lead to it taking a majority stake in what will be the world's second largest nuclear fuel manufacturer. Reaction to the news is reported. This has been muted in the United Kingdom, mixed in Germany and adverse in France because of the implications for the Siemens' Framatone collaboration. (UK)

  18. Molecular catalysis science: Perspective on unifying the fields of catalysis.

    Science.gov (United States)

    Ye, Rong; Hurlburt, Tyler J; Sabyrov, Kairat; Alayoglu, Selim; Somorjai, Gabor A

    2016-05-10

    Colloidal chemistry is used to control the size, shape, morphology, and composition of metal nanoparticles. Model catalysts as such are applied to catalytic transformations in the three types of catalysts: heterogeneous, homogeneous, and enzymatic. Real-time dynamics of oxidation state, coordination, and bonding of nanoparticle catalysts are put under the microscope using surface techniques such as sum-frequency generation vibrational spectroscopy and ambient pressure X-ray photoelectron spectroscopy under catalytically relevant conditions. It was demonstrated that catalytic behavior and trends are strongly tied to oxidation state, the coordination number and crystallographic orientation of metal sites, and bonding and orientation of surface adsorbates. It was also found that catalytic performance can be tuned by carefully designing and fabricating catalysts from the bottom up. Homogeneous and heterogeneous catalysts, and likely enzymes, behave similarly at the molecular level. Unifying the fields of catalysis is the key to achieving the goal of 100% selectivity in catalysis.

  19. New and future developments in catalysis catalysis by nanoparticles

    CERN Document Server

    Suib, Steven L

    2013-01-01

    New and Future Developments in Catalysis is a package of seven books that compile the latest ideas concerning alternate and renewable energy sources and the role that catalysis plays in converting new renewable feedstock into biofuels and biochemicals. Both homogeneous and heterogeneous catalysts and catalytic processes will be discussed in a unified and comprehensive approach. There will be extensive cross-referencing within all volumes. The use of catalysts in the nanoscale offers various advantages (increased efficiency and less byproducts), and these are discussed in this volume along with the various catalytic processes using nanoparticles. However, this is not without any risks and the safety aspects and effects on humans and the environment are still unknown. The present data as well as future needs are all part of this volume along with the economics involved. Offers in-depth coverage of all catalytic topics of current interest and outlines future challenges and research areas A clear and visual descr...

  20. Time-varying mixed logit model for vehicle merging behavior in work zone merging areas.

    Science.gov (United States)

    Weng, Jinxian; Du, Gang; Li, Dan; Yu, Yao

    2018-08-01

    This study aims to develop a time-varying mixed logit model for the vehicle merging behavior in work zone merging areas during the merging implementation period from the time of starting a merging maneuver to that of completing the maneuver. From the safety perspective, vehicle crash probability and severity between the merging vehicle and its surrounding vehicles are regarded as major factors influencing vehicle merging decisions. Model results show that the model with the use of vehicle crash risk probability and severity could provide higher prediction accuracy than previous models with the use of vehicle speeds and gap sizes. It is found that lead vehicle type, through lead vehicle type, through lag vehicle type, crash probability of the merging vehicle with respect to the through lag vehicle, crash severities of the merging vehicle with respect to the through lead and lag vehicles could exhibit time-varying effects on the merging behavior. One important finding is that the merging vehicle could become more and more aggressive in order to complete the merging maneuver as quickly as possible over the elapsed time, even if it has high vehicle crash risk with respect to the through lead and lag vehicles. Copyright © 2018 Elsevier Ltd. All rights reserved.

  1. Visible-light photoredox catalyzed synthesis of pyrroloisoquinolines via organocatalytic oxidation/[3 + 2] cycloaddition/oxidative aromatization reaction cascade with Rose Bengal

    Directory of Open Access Journals (Sweden)

    Carlos Vila

    2014-05-01

    Full Text Available Pyrrolo[2,1-a]isoquinoline alkaloids have been prepared via a visible light photoredox catalyzed oxidation/[3 + 2] cycloaddition/oxidative aromatization cascade using Rose Bengal as an organo-photocatalyst. A variety of pyrroloisoquinolines have been obtained in good yields under mild and metal-free reaction conditions.

  2. Chemical catalysis in biodiesel production (I): enzymatic catalysis processes

    International Nuclear Information System (INIS)

    Jachmarian, I.; Dobroyan, M.; Veira, J.; Vieitez, I.; Mottini, M.; Segura, N.; Grompone, M.

    2009-01-01

    There are some well known advantages related with the substitution of chemical catalysis by enzymatic catalysis processes.Some commercial immobilized lipases are useful for the catalysis of bio diesel reaction, which permits the achievement of high conversions and the recovery of high purity products, like a high quality glycerine. The main disadvantage of this alternative method is related with the last inactivation of the enzyme (by both the effect of the alcohol and the absorption of glycerol on catalyst surface), which added to the high cost of the catalyst, produces an unfavourable economical balance of the entire process. In the work the efficiency of two commercial immobilized lipases (Lipozyme TL IM y Novozyme 435 NNovozymes-Dinamarca) in the catalysis of the continuous transesterification of sunflower oil with different alcohols was studied. The intersolubility of the different mixturesinvolving reactans (S oil/alkyl esters/alcohol) and products (P mixtures with a higher content of 1% of glycerol,while for ethanol homogeneous mixtures were obtained at 12% of glycerol (44.44 12).Using and ethanolic substrate at the proportion S=19:75:6 and Lipozyme TL IM, it was possible to achieve a 98% of convertion to the corresponding biodiesel.When Novozymes 435 catalyzed the process it was possible to increase the oil concentration in the substrateaccording to proportion S=35:30:35, and a 78% conversion was obtained. The productivity shown by the firt enzyme was 70mg biodiesel g enzime-1, hora-1 while with the second one the productivity increased to 230. Results suggested that the convenient adjustement of substrate composition with the addition of biodiesel to reactants offers an efficient method for maximizing the enzyme productivity, hence improving the profitability of the enzymatic catalyzed process. (author)

  3. Facile Synthesis of Worm-like Micelles by Visible Light Mediated Dispersion Polymerization Using Photoredox Catalyst.

    Science.gov (United States)

    Yeow, Jonathan; Xu, Jiangtao; Boyer, Cyrille

    2016-06-08

    Presented herein is a protocol for the facile synthesis of worm-like micelles by visible light mediated dispersion polymerization. This approach begins with the synthesis of a hydrophilic poly(oligo(ethylene glycol) methyl ether methacrylate) (POEGMA) homopolymer using reversible addition-fragmentation chain-transfer (RAFT) polymerization. Under mild visible light irradiation (λ = 460 nm, 0.7 mW/cm(2)), this macro-chain transfer agent (macro-CTA) in the presence of a ruthenium based photoredox catalyst, Ru(bpy)3Cl2 can be chain extended with a second monomer to form a well-defined block copolymer in a process known as Photoinduced Electron Transfer RAFT (PET-RAFT). When PET-RAFT is used to chain extend POEGMA with benzyl methacrylate (BzMA) in ethanol (EtOH), polymeric nanoparticles with different morphologies are formed in situ according to a polymerization-induced self-assembly (PISA) mechanism. Self-assembly into nanoparticles presenting POEGMA chains at the corona and poly(benzyl methacrylate) (PBzMA) chains in the core occurs in situ due to the growing insolubility of the PBzMA block in ethanol. Interestingly, the formation of highly pure worm-like micelles can be readily monitored by observing the onset of a highly viscous gel in situ due to nanoparticle entanglements occurring during the polymerization. This process thereby allows for a more reproducible synthesis of worm-like micelles simply by monitoring the solution viscosity during the course of the polymerization. In addition, the light stimulus can be intermittently applied in an ON/OFF manner demonstrating temporal control over the nanoparticle morphology.

  4. Catalysis in the Primordial World

    Directory of Open Access Journals (Sweden)

    Nenad Raos

    2017-11-01

    Full Text Available Catalysis provides orderly prebiotic synthesis and eventually its evolution into autocatalytic (self-reproduction systems. Research on homogeneous catalysis is concerned mostly with random peptide synthesis and the chances to produce catalytic peptide oligomers. Synthesis of ribose via formose reaction was found to be catalysed by B(OH4−, presumably released by weathering of borate minerals. Oxide and clay mineral surfaces provide catalytic sites for the synthesis of oligopeptides and oligonucleotides. Chemoautotrophic or iron-sulphur-world theory assumes that the first (pioneer organisms developed by catalytic processes on (Fe/NiS particles formed near/close hydrothermal vents. The review provides an overlay of possible catalytic reactions in prebiotic environment, discussing their selectivity (regioselectivity, stereoselectivity as well as geological availability of catalytic minerals and geochemical conditions enabling catalytic reactions on early Earth.

  5. Asymmetric cation-binding catalysis

    DEFF Research Database (Denmark)

    Oliveira, Maria Teresa; Lee, Jiwoong

    2017-01-01

    The employment of metal salts is quite limited in asymmetric catalysis, although it would provide an additional arsenal of safe and inexpensive reagents to create molecular functions with high optical purity. Cation chelation by polyethers increases the salts' solubility in conventional organic...... solvents, thus increasing their applicability in synthesis. The expansion of this concept to chiral polyethers led to the emergence of asymmetric cation-binding catalysis, where chiral counter anions are generated from metal salts, particularly using BINOL-based polyethers. Alkali metal salts, namely KF...... highly enantioselective silylation reactions in polyether-generated chiral environments, and leading to a record-high turnover in asymmetric organocatalysis. This can lead to further applications by the asymmetric use of other inorganic salts in various organic transformations....

  6. Cosmic strings and baryon decay catalysis

    Energy Technology Data Exchange (ETDEWEB)

    Gregory, R.; Perkins, W.B.; Davis, A.C.; Brandenberger, R.H. (Fermi National Accelerator Lab., Batavia, IL (USA); Cambridge Univ. (UK); Brown Univ., Providence, RI (USA). Dept. of Physics)

    1989-09-01

    Cosmic strings, like monopoles, can catalyze proton decay. For integer charged fermions, the cross section for catalysis is not amplified, unlike in the case of monopoles. We review the catalysis processes both in the free quark and skyrmion pictures and discuss the implications for baryogenesis. We present a computation of the cross section for monopole catalyzed skyrmion decay using classical physics. We also discuss some effects which can screen catalysis processes. 32 refs., 1 fig.

  7. Magnetic monopole catalysis of proton decay

    International Nuclear Information System (INIS)

    Marciano, W.J.; Salvino, D.

    1986-09-01

    Catalysis of proton decay by GUT magnetic monopoles (the Rubakov-Callan effect) is discussed. Combining a short-distance cross section calculation by Bernreuther and Craigie with the long-distance velocity dependent distortion factors of Arafune and Fukugita, catalysis rate predictions which can be compared with experiment are obtained. At present, hydrogen rich detectors such as water (H 2 O) and methane (CH 4 ) appear to be particularly well suited for observing catalysis by very slow monopoles. 17 refs., 1 fig

  8. Cosmic strings and baryon decay catalysis

    International Nuclear Information System (INIS)

    Gregory, R.; Perkins, W.B.; Davis, A.C.; Brandenberger, R.H.; Cambridge Univ.; Brown Univ., Providence, RI

    1989-09-01

    Cosmic strings, like monopoles, can catalyze proton decay. For integer charged fermions, the cross section for catalysis is not amplified, unlike in the case of monopoles. We review the catalysis processes both in the free quark and skyrmion pictures and discuss the implications for baryogenesis. We present a computation of the cross section for monopole catalyzed skyrmion decay using classical physics. We also discuss some effects which can screen catalysis processes. 32 refs., 1 fig

  9. Bouncing and Merging of Liquid Jets

    Science.gov (United States)

    Saha, Abhishek; Li, Minglei; Law, Chung K.

    2014-11-01

    Collision of two fluid jets is a technique that is utilized in many industrial applications, such as in rocket engines, to achieve controlled mixing, atomization and sometimes liquid phase reactions. Thus, the dynamics of colliding jets have direct impact on the performance, efficiency and reliability of such applications. In analogy with the dynamics of droplet-droplet collision, in this work we have experimentally demonstrated, for n-alkane hydrocarbons as well as water, that with increasing impact inertia obliquely colliding jets also exhibit the same nonmonotonic responses of merging, bouncing, merging again, and merging followed by disintegration; and that the continuous entrainment of the boundary layer air over the jet surface into the colliding interfacial region leads to two distinguishing features of jet collision, namely: there exists a maximum impact angle beyond which merging is always possible, and that merging is inhibited and then promoted with increasing pressure. These distinct response regimes were mapped and explained on the bases of impact inertia, deformation of the jet surface, viscous loss within the jet interior, and the thickness and pressure build-up within the interfacial region in order to activate the attractive surface van der Waals force to effect merging.

  10. Cooperative catalysis designing efficient catalysts for synthesis

    CERN Document Server

    Peters, René

    2015-01-01

    Written by experts in the field, this is a much-needed overview of the rapidly emerging field of cooperative catalysis. The authors focus on the design and development of novel high-performance catalysts for applications in organic synthesis (particularly asymmetric synthesis), covering a broad range of topics, from the latest progress in Lewis acid / Br?nsted base catalysis to e.g. metal-assisted organocatalysis, cooperative metal/enzyme catalysis, and cooperative catalysis in polymerization reactions and on solid surfaces. The chapters are classified according to the type of cooperating acti

  11. Solid acid catalysis from fundamentals to applications

    CERN Document Server

    Hattori, Hideshi

    2014-01-01

    IntroductionTypes of solid acid catalystsAdvantages of solid acid catalysts Historical overviews of solid acid catalystsFuture outlookSolid Acids CatalysisDefinition of acid and base -Brnsted acid and Lewis acid-Acid sites on surfacesAcid strengthRole of acid sites in catalysisBifunctional catalysisPore size effect on catalysis -shape selectivity-Characterization of Solid Acid Catalysts Indicator methodTemperature programmed desorption (TPD) of ammoniaCalorimetry of adsorption of basic moleculesInfrare

  12. Hydrogen Production by Homogeneous Catalysis: Alcohol Acceptorless Dehydrogenation

    DEFF Research Database (Denmark)

    Nielsen, Martin

    2015-01-01

    in hydrogen production from biomass using homogeneous catalysis. Homogeneous catalysis has the advance of generally performing transformations at much milder conditions than traditional heterogeneous catalysis, and hence it constitutes a promising tool for future applications for a sustainable energy sector...

  13. Merged ozone profiles from four MIPAS processors

    Science.gov (United States)

    Laeng, Alexandra; von Clarmann, Thomas; Stiller, Gabriele; Dinelli, Bianca Maria; Dudhia, Anu; Raspollini, Piera; Glatthor, Norbert; Grabowski, Udo; Sofieva, Viktoria; Froidevaux, Lucien; Walker, Kaley A.; Zehner, Claus

    2017-04-01

    The Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) was an infrared (IR) limb emission spectrometer on the Envisat platform. Currently, there are four MIPAS ozone data products, including the operational Level-2 ozone product processed at ESA, with the scientific prototype processor being operated at IFAC Florence, and three independent research products developed by the Istituto di Fisica Applicata Nello Carrara (ISAC-CNR)/University of Bologna, Oxford University, and the Karlsruhe Institute of Technology-Institute of Meteorology and Climate Research/Instituto de Astrofísica de Andalucía (KIT-IMK/IAA). Here we present a dataset of ozone vertical profiles obtained by merging ozone retrievals from four independent Level-2 MIPAS processors. We also discuss the advantages and the shortcomings of this merged product. As the four processors retrieve ozone in different parts of the spectra (microwindows), the source measurements can be considered as nearly independent with respect to measurement noise. Hence, the information content of the merged product is greater and the precision is better than those of any parent (source) dataset. The merging is performed on a profile per profile basis. Parent ozone profiles are weighted based on the corresponding error covariance matrices; the error correlations between different profile levels are taken into account. The intercorrelations between the processors' errors are evaluated statistically and are used in the merging. The height range of the merged product is 20-55 km, and error covariance matrices are provided as diagnostics. Validation of the merged dataset is performed by comparison with ozone profiles from ACE-FTS (Atmospheric Chemistry Experiment-Fourier Transform Spectrometer) and MLS (Microwave Limb Sounder). Even though the merging is not supposed to remove the biases of the parent datasets, around the ozone volume mixing ratio peak the merged product is found to have a smaller (up to 0.1 ppmv

  14. Fundamental concepts in heterogeneous catalysis

    CERN Document Server

    Norskov, Jens K; Abild-Pedersen, Frank; Bligaard, Thomas

    2014-01-01

    This book is based on a graduate course and suitable as a primer for any newcomer to the field, this book is a detailed introduction to the experimental and computational methods that are used to study how solid surfaces act as catalysts.   Features include:First comprehensive description of modern theory of heterogeneous catalysisBasis for understanding and designing experiments in the field   Allows reader to understand catalyst design principlesIntroduction to important elements of energy transformation technologyTest driven at Stanford University over several semesters

  15. DOE Laboratory Catalysis Research Symposium - Abstracts

    Energy Technology Data Exchange (ETDEWEB)

    Dunham, T.

    1999-02-01

    The conference consisted of two sessions with the following subtopics: (1) Heterogeneous Session: Novel Catalytic Materials; Photocatalysis; Novel Processing Conditions; Metals and Sulfides; Nuclear Magnetic Resonance; Metal Oxides and Partial Oxidation; Electrocatalysis; and Automotive Catalysis. (2) Homogeneous Catalysis: H-Transfer and Alkane Functionalization; Biocatalysis; Oxidation and Photocatalysis; and Novel Medical, Methods, and Catalyzed Reactions.

  16. Chemoselective Radical Dehalogenation and C-C Bond Formation on Aryl Halide Substrates Using Organic Photoredox Catalysts.

    Science.gov (United States)

    Poelma, Saemi O; Burnett, G Leslie; Discekici, Emre H; Mattson, Kaila M; Treat, Nicolas J; Luo, Yingdong; Hudson, Zachary M; Shankel, Shelby L; Clark, Paul G; Kramer, John W; Hawker, Craig J; Read de Alaniz, Javier

    2016-08-19

    Despite the number of methods available for dehalogenation and carbon-carbon bond formation using aryl halides, strategies that provide chemoselectivity for systems bearing multiple carbon-halogen bonds are still needed. Herein, we report the ability to tune the reduction potential of metal-free phenothiazine-based photoredox catalysts and demonstrate the application of these catalysts for chemoselective carbon-halogen bond activation to achieve C-C cross-coupling reactions as well as reductive dehalogenations. This procedure works both for conjugated polyhalides as well as unconjugated substrates. We further illustrate the usefulness of this protocol by intramolecular cyclization of a pyrrole substrate, an advanced building block for a family of natural products known to exhibit biological activity.

  17. Photo-redox activated drug delivery systems operating under two photon excitation in the near-IR.

    Science.gov (United States)

    Guardado-Alvarez, Tania M; Devi, Lekshmi Sudha; Vabre, Jean-Marie; Pecorelli, Travis A; Schwartz, Benjamin J; Durand, Jean-Olivier; Mongin, Olivier; Blanchard-Desce, Mireille; Zink, Jeffrey I

    2014-05-07

    We report the design and synthesis of a nano-container consisting of mesoporous silica nanoparticles with the pore openings covered by "snap-top" caps that are opened by near-IR light. A photo transducer molecule that is a reducing agent in an excited electronic state is covalently attached to the system. Near IR two-photon excitation causes inter-molecular electron transfer that reduces a disulfide bond holding the cap in place, thus allowing the cargo molecules to escape. We describe the operation of the "snap-top" release mechanism by both one- and two-photon activation. This system presents a proof of concept of a near-IR photoredox-induced nanoparticle delivery system that may lead to a new type of photodynamic drug release therapy.

  18. Computational Design of Clusters for Catalysis

    Science.gov (United States)

    Jimenez-Izal, Elisa; Alexandrova, Anastassia N.

    2018-04-01

    When small clusters are studied in chemical physics or physical chemistry, one perhaps thinks of the fundamental aspects of cluster electronic structure, or precision spectroscopy in ultracold molecular beams. However, small clusters are also of interest in catalysis, where the cold ground state or an isolated cluster may not even be the right starting point. Instead, the big question is: What happens to cluster-based catalysts under real conditions of catalysis, such as high temperature and coverage with reagents? Myriads of metastable cluster states become accessible, the entire system is dynamic, and catalysis may be driven by rare sites present only under those conditions. Activity, selectivity, and stability are highly dependent on size, composition, shape, support, and environment. To probe and master cluster catalysis, sophisticated tools are being developed for precision synthesis, operando measurements, and multiscale modeling. This review intends to tell the messy story of clusters in catalysis.

  19. "Nanocrystal bilayer for tandem catalysis"

    Energy Technology Data Exchange (ETDEWEB)

    Yamada, Yusuke; Tsung, Chia Kuang; Huang, Wenyu; Huo, Ziyang; E.Habas, Susan E; Soejima, Tetsuro; Aliaga, Cesar E; Samorjai, Gabor A; Yang, Peidong

    2011-01-24

    Supported catalysts are widely used in industry and can be optimized by tuning the composition and interface of the metal nanoparticles and oxide supports. Rational design of metal-metal oxide interfaces in nanostructured catalysts is critical to achieve better reaction activities and selectivities. We introduce here a new class of nanocrystal tandem catalysts that have multiple metal-metal oxide interfaces for the catalysis of sequential reactions. We utilized a nanocrystal bilayer structure formed by assembling platinum and cerium oxide nanocube monolayers of less than 10 nm on a silica substrate. The two distinct metal-metal oxide interfaces, CeO2-Pt and Pt-SiO2, can be used to catalyse two distinct sequential reactions. The CeO2-Pt interface catalysed methanol decomposition to produce CO and H2, which were subsequently used for ethylene hydroformylation catalysed by the nearby Pt-SiO2 interface. Consequently, propanal was produced selectively from methanol and ethylene on the nanocrystal bilayer tandem catalyst. This new concept of nanocrystal tandem catalysis represents a powerful approach towards designing high-performance, multifunctional nanostructured catalysts

  20. Curvature bound from gravitational catalysis

    Science.gov (United States)

    Gies, Holger; Martini, Riccardo

    2018-04-01

    We determine bounds on the curvature of local patches of spacetime from the requirement of intact long-range chiral symmetry. The bounds arise from a scale-dependent analysis of gravitational catalysis and its influence on the effective potential for the chiral order parameter, as induced by fermionic fluctuations on a curved spacetime with local hyperbolic properties. The bound is expressed in terms of the local curvature scalar measured in units of a gauge-invariant coarse-graining scale. We argue that any effective field theory of quantum gravity obeying this curvature bound is safe from chiral symmetry breaking through gravitational catalysis and thus compatible with the simultaneous existence of chiral fermions in the low-energy spectrum. With increasing number of dimensions, the curvature bound in terms of the hyperbolic scale parameter becomes stronger. Applying the curvature bound to the asymptotic safety scenario for quantum gravity in four spacetime dimensions translates into bounds on the matter content of particle physics models.

  1. Cosmic ray modulation and merged interaction regions

    International Nuclear Information System (INIS)

    Burlaga, L.F.; Goldstein, M.L.; Mcdonald, F.B.

    1985-01-01

    Beyond several AU, interactions among shocks and streams give rise to merged interaction regions in which the magnetic field is turbulent. The integral intensity of . 75 MeV/Nuc cosmic rays at Voyager is generally observed to decrease when a merged interaction region moves past the spacecraft and to increase during the passage of a rarefaction region. When the separation between interaction regions is relatively large, the cosmic ray intensity tends to increase on a scale of a few months. This was the case at Voyager 1 from July 1, 1983 to May 1, 1984, when the spacecraft moved from 16.7 to 19.6 AU. Changes in cosmic ray intensity were related to the magnetic field strength in a simple way. It is estimated that the diffusion coefficient in merged interaction regions at this distance is similar to 0.6 x 10 to the 22nd power sq cm/s

  2. Application studies of spherical tokamak plasma merging

    International Nuclear Information System (INIS)

    Ono, Yasushi; Inomoto, Michiaki

    2012-01-01

    The experiment of plasma merging and heating has long history in compact torus studies since Wells. The study of spherical tokamak (ST), starting from TS-3 plasma merging experiment of Tokyo University in the late 1980s, is followed by START of Culham laboratory in the 1900s, TS-4 and UTST of Tokyo University and MAST of Culham laboratory in the 2000s, and last year by VEST of Soul University. ST has the following advantages: 1) plasma heating by magnetic reconnection at a MW-GW level, 2) rapid start-up of high beta plasma, 3) current drive/flux multiplication and distribution control of ST plasma, 4) fueling and helium-ash exhaust. In the present article, we emphasize that magnetic reconnection and plasma merging phenomena are important in ST plasma study as well as in plasma physics. (author)

  3. Interpreting quantum discord through quantum state merging

    International Nuclear Information System (INIS)

    Madhok, Vaibhav; Datta, Animesh

    2011-01-01

    We present an operational interpretation of quantum discord based on the quantum state merging protocol. Quantum discord is the markup in the cost of quantum communication in the process of quantum state merging, if one discards relevant prior information. Our interpretation has an intuitive explanation based on the strong subadditivity of von Neumann entropy. We use our result to provide operational interpretations of other quantities like the local purity and quantum deficit. Finally, we discuss in brief some instances where our interpretation is valid in the single-copy scenario.

  4. Merging history of three bimodal clusters

    Science.gov (United States)

    Maurogordato, S.; Sauvageot, J. L.; Bourdin, H.; Cappi, A.; Benoist, C.; Ferrari, C.; Mars, G.; Houairi, K.

    2011-01-01

    We present a combined X-ray and optical analysis of three bimodal galaxy clusters selected as merging candidates at z ~ 0.1. These targets are part of MUSIC (MUlti-Wavelength Sample of Interacting Clusters), which is a general project designed to study the physics of merging clusters by means of multi-wavelength observations. Observations include spectro-imaging with XMM-Newton EPIC camera, multi-object spectroscopy (260 new redshifts), and wide-field imaging at the ESO 3.6 m and 2.2 m telescopes. We build a global picture of these clusters using X-ray luminosity and temperature maps together with galaxy density and velocity distributions. Idealized numerical simulations were used to constrain the merging scenario for each system. We show that A2933 is very likely an equal-mass advanced pre-merger ~200 Myr before the core collapse, while A2440 and A2384 are post-merger systems (~450 Myr and ~1.5 Gyr after core collapse, respectively). In the case of A2384, we detect a spectacular filament of galaxies and gas spreading over more than 1 h-1 Mpc, which we infer to have been stripped during the previous collision. The analysis of the MUSIC sample allows us to outline some general properties of merging clusters: a strong luminosity segregation of galaxies in recent post-mergers; the existence of preferential axes - corresponding to the merging directions - along which the BCGs and structures on various scales are aligned; the concomitance, in most major merger cases, of secondary merging or accretion events, with groups infalling onto the main cluster, and in some cases the evidence of previous merging episodes in one of the main components. These results are in good agreement with the hierarchical scenario of structure formation, in which clusters are expected to form by successive merging events, and matter is accreted along large-scale filaments. Based on data obtained with the European Southern Observatory, Chile (programs 072.A-0595, 075.A-0264, and 079.A-0425

  5. Visible-Light Photoredox-Catalyzed Giese Reaction: Decarboxylative Addition of Amino Acid Derived α-Amino Radicals to Electron-Deficient Olefins

    KAUST Repository

    Millet, Anthony; Lefebvre, Quentin; Rueping, Magnus

    2016-01-01

    A tin- and halide-free, visible-light photoredox-catalyzed Giese reaction was developed. Primary and secondary α-amino radicals were generated readily from amino acids in the presence of catalytic amounts of an iridium photocatalyst. The reactivity of the α-amino radicals has been evaluated for the functionalization of a variety of activated olefins. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

  6. Visible-Light Photoredox-Catalyzed Giese Reaction: Decarboxylative Addition of Amino Acid Derived α-Amino Radicals to Electron-Deficient Olefins

    KAUST Repository

    Millet, Anthony

    2016-06-20

    A tin- and halide-free, visible-light photoredox-catalyzed Giese reaction was developed. Primary and secondary α-amino radicals were generated readily from amino acids in the presence of catalytic amounts of an iridium photocatalyst. The reactivity of the α-amino radicals has been evaluated for the functionalization of a variety of activated olefins. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

  7. Attractor merging crisis in chaotic business cycles

    International Nuclear Information System (INIS)

    Chian, Abraham C.-L.; Borotto, Felix A.; Rempel, Erico L.; Rogers, Colin

    2005-01-01

    A numerical study is performed on a forced-oscillator model of nonlinear business cycles. An attractor merging crisis due to a global bifurcation is analyzed using the unstable periodic orbits and their associated stable and unstable manifolds. Characterization of crisis can improve our ability to forecast sudden major changes in economic systems

  8. Modeling merging behavior at lane drops.

    Science.gov (United States)

    2015-02-01

    In work-zone configurations where lane drops are present, merging of traffic at the taper presents an operational concern. In : addition, as flow through the work zone is reduced, the relative traffic safety of the work zone is also reduced. Improvin...

  9. Algorithm 426 : Merge sort algorithm [M1

    NARCIS (Netherlands)

    Bron, C.

    1972-01-01

    Sorting by means of a two-way merge has a reputation of requiring a clerically complicated and cumbersome program. This ALGOL 60 procedure demonstrates that, using recursion, an elegant and efficient algorithm can be designed, the correctness of which is easily proved [2]. Sorting n objects gives

  10. Cluster Physics with Merging Galaxy Clusters

    Directory of Open Access Journals (Sweden)

    Sandor M. Molnar

    2016-02-01

    Full Text Available Collisions between galaxy clusters provide a unique opportunity to study matter in a parameter space which cannot be explored in our laboratories on Earth. In the standard LCDM model, where the total density is dominated by the cosmological constant ($Lambda$ and the matter density by cold dark matter (CDM, structure formation is hierarchical, and clusters grow mostly by merging.Mergers of two massive clusters are the most energetic events in the universe after the Big Bang,hence they provide a unique laboratory to study cluster physics.The two main mass components in clusters behave differently during collisions:the dark matter is nearly collisionless, responding only to gravity, while the gas is subject to pressure forces and dissipation, and shocks and turbulenceare developed during collisions. In the present contribution we review the different methods used to derive the physical properties of merging clusters. Different physical processes leave their signatures on different wavelengths, thusour review is based on a multifrequency analysis. In principle, the best way to analyze multifrequency observations of merging clustersis to model them using N-body/HYDRO numerical simulations. We discuss the results of such detailed analyses.New high spatial and spectral resolution ground and space based telescopeswill come online in the near future. Motivated by these new opportunities,we briefly discuss methods which will be feasible in the near future in studying merging clusters.

  11. Surface science and heterogeneous catalysis

    International Nuclear Information System (INIS)

    Somorjai, G.A.

    1980-05-01

    The catalytic reactions studied include hydrocarbon conversion over platinum, the transition metal-catalyzed hydrogenation of carbon monoxide, and the photocatalyzed dissociation of water over oxide surfaces. The method of combined surface science and catalytic studies is similar to those used in synthetic organic chemistry. The single-crystal models for the working catalyst are compared with real catalysts by comparing the rates of cyclopropane ring opening on platinum and the hydrogenation of carbon monoxide on rhodium single crystal surface with those on practical commercial catalyst systems. Excellent agreement was obtained for these reactions. This document reviews what was learned about heterogeneous catalysis from these surface science approaches over the past 15 years and present models of the active catalyst surface

  12. Preparation for electron ring - plasma ring merging experiments in RECE-MERGE

    International Nuclear Information System (INIS)

    Taggart, D.; Sekiguchi, A.; Fleischmann, H.H.

    1986-01-01

    The formation of a mixed-CT using relativistic electron rings and gun-produced plasma rings by MERGE-ing them axially is simulated. This process is similar to the axial stacking of relativistic electron rings in RECE-Christa. The results of their first plasm production experiment are reported here. After study of the gun-produced plasma's properties is completed, the gun will be mounted at the downstream end of the vacuum tank and the source of relativistic electron rings will be at the upstream end. The two rings, formed at opposite ends of the tank, will be translated axially and merged

  13. Tandem catalysis: a new approach to polymers.

    Science.gov (United States)

    Robert, Carine; Thomas, Christophe M

    2013-12-21

    The creation of polymers by tandem catalysis represents an exciting frontier in materials science. Tandem catalysis is one of the strategies used by Nature for building macromolecules. Living organisms generally synthesize macromolecules by in vivo enzyme-catalyzed chain growth polymerization reactions using activated monomers that have been formed within cells during complex metabolic processes. However, these biological processes rely on highly complex biocatalysts, thus limiting their industrial applications. In order to obtain polymers by tandem catalysis, homogeneous and enzyme catalysts have played a leading role in the last two decades. In the following feature article, we will describe selected published efforts to achieve these research goals.

  14. Supported Ionic Liquid Phase (SILP) catalysis

    DEFF Research Database (Denmark)

    Riisager, Anders; Fehrmann, Rasmus; Haumann, Marco

    2006-01-01

    Applications of ionic liquids to replace conventional solvents in homogeneous transition-metal catalysis have increased significantly during the last decade. Biphasic ionic liquid/organic liquid systems offer advantages with regard to product separation, catalyst stability, and recycling...... but utilise in the case of fast chemical reactions only a small amount of expensive ionic liquid and catalyst. The novel Supported Ionic Liquid Phase (SILP) catalysis concept overcomes these drawbacks and allows the use of fixed-bed reactors for continuous reactions. In this Microreview the SILP catalysis...

  15. Relation between Hydrogen Evolution and Hydrodesulfurization Catalysis

    DEFF Research Database (Denmark)

    Šaric, Manuel; Moses, Poul Georg; Rossmeisl, Jan

    2016-01-01

    A relation between hydrogen evolution and hydrodesulfurization catalysis was found by density functional theory calculations. The hydrogen evolution reaction and the hydrogenation reaction in hydrodesulfurization share hydrogen as a surface intermediate and, thus, have a common elementary step...

  16. Special section on Nano-Catalysis

    CSIR Research Space (South Africa)

    Makgwane, PR

    2013-01-01

    Full Text Available to achieve sustainable and green catalytic processes. The special issue contains 40 peer reviewed scientific papers that include four comprehensive review articles contributions from the invited experts in the respective catalysis fields....

  17. Current trends of surface science and catalysis

    CERN Document Server

    Park, Jeong Young

    2014-01-01

    Including detail on applying surface science in renewable energy conversion, this book covers the latest results on model catalysts including single crystals, bridging "materials and pressure gaps", and hot electron flows in heterogeneous catalysis.

  18. Faraday Discussions meeting Catalysis for Fuels.

    Science.gov (United States)

    Fischer, Nico; Kondrat, Simon A; Shozi, Mzamo

    2017-05-02

    Welcome to Africa was the motto when after more than 100 years the flag ship conference series of the Royal Society of Chemistry, the Faraday Discussions was hosted for the first time on the African Continent. Under the fitting topic 'Catalysis for Fuels' over 120 delegates followed the invitation by the conference chair Prof. Graham Hutchings FRS (Cardiff Catalysis Institute), his organizing committee and the co-organizing DST-NRF Centre of Excellence in Catalysis c*change (). In the presentations of 21 invited speakers and 59 posters, cutting edge research in the field of catalysis for fuels, designing new catalysts for synthetic fuels, hydrocarbon conversion in the production of synthetic fuels and novel photocatalysis was presented over the two-day meeting. The scene was set by the opening lecture of Prof. Enrique Iglesias (UC Berkeley) and wrapped-up with the concluding remarks by Philip Gibson (SASOL).

  19. Advancing Sustainable Catalysis with Magnetite Surface ...

    Science.gov (United States)

    This article surveys the recent developments in the synthesis, surface modification, and synthetic applications of magnetitenanoparticles. The emergence of iron(II,III) oxide (triiron tetraoxide or magnetite; Fe3O4, or FeO•Fe2O3) nanoparticles as a sustainable support in heterogeneous catalysis is highlighted. Use of an oxide of earth-abundant iron for various applications in catalysis and environmental remediation.

  20. New developments in oxidation catalysis

    Energy Technology Data Exchange (ETDEWEB)

    Rosowski, F. [BASF SE, Ludwigshafen (Germany)

    2011-07-01

    The impact of heterogeneous catalysis on the economy can be depicted by the global revenue of the chemical industry in 2006, which accounted for 2200 billion Euros with a share of all chemical products produced applying heterogeneous catalysis of about two thirds. [1] The range of products is enormous and they contribute greatly to the quality of our lifes. The advancement in the development of basic and intermediate chemical products is crucially dependent on either the further development of existing catalyst systems or the development of new catalysts and key to success for the chemical industry. Within the context of oxidation catalysis, the following driving forces are guiding research activities: There is a continuous desire to increase the selectivity of a given process in response to both economic as well as ecological needs and taking advantage of higher efficiencies in terms of cost savings and a better utilization of raw materials. A second motivation focuses on raw material change to all abundant and competitive feedstocks requiring both new developments in catalyst design as well as process technology. A more recent motivation refers to the use of metal oxide redox systems which are key to success for the development of novel technologies allowing for the separation of carbon dioxide and the use of carbon dioxide as a feedstock molecule as well as storing renewable energy in a chemical. To date, general ab initio approaches are known for the design of novel catalytic materials only for a few chemical reactions, whereas most industrial catalytic processes have been developed by empirical methods. [2] The development of catalytic materials are either based on the targeted synthesis of catalytic lead structures as well as high throughput methods that allow for the screening of a large range of parameters. [3 - 5] The successful development of catalysts together with reactor technology has led to both significant savings in raw materials and emissions. The

  1. The Astrophysics of Merging Black Holes

    Science.gov (United States)

    Schnittman, Jeremy D.

    2011-01-01

    When two supermassive black holes (SMBHs) approach within 1-10 mpc, gravitational wave (GW) losses begin to dominate the evolution of the binary, pushing the system to merge in a relatively small time. During this final inspiral regime, the system will emit copious energy in GWs, which should be directly detectable by pulsar timing arrays and space-based interferometers. At the same time, any gas or stars in the immediate vicinity of the merging 5MBHs can get heated and produce bright electromagnetic (EM) counterparts to the GW signals. We present here a number of possible mechanisms by which simultaneous EM and GW signals will yield valuable new information about galaxy evolution, accretion disk dynamics, and fundamental physics in the most extreme gravitational fields.

  2. Team Climate Inventory with a merged organization.

    Science.gov (United States)

    Dackert, Ingrid; Brenner, Sten-Olof; Johansson, Curt R

    2002-10-01

    The present study examines the team climate for innovation in work teams within a newly merged organization. Four teams working at a regional head office of a Social Insurance organization answered the Team Climate Inventory. The results were compared to those of a study by Agrell and Gustafson of more stable teams. The comparison showed that participative safety and support for innovation were rated lower and that vision was rated higher in the newly merged teams. The 38-item original inventory was used and based on the results, a 1999 proposed shortened version of 14 items by Kivimäki and Elovainio was compared with the original one. Analysis indicated that the short version can be a valid alternative to the original version but that further testing of the short version is needed.

  3. Modeling merging behavior at lane drops : [tech transfer summary].

    Science.gov (United States)

    2015-02-01

    A better understanding of the merging behavior of drivers will lead : to the development of better lane-drop traffic-control plans and : strategies, which will provide better guidance to drivers for safer : merging.

  4. Merging Digital Surface Models Implementing Bayesian Approaches

    Science.gov (United States)

    Sadeq, H.; Drummond, J.; Li, Z.

    2016-06-01

    In this research different DSMs from different sources have been merged. The merging is based on a probabilistic model using a Bayesian Approach. The implemented data have been sourced from very high resolution satellite imagery sensors (e.g. WorldView-1 and Pleiades). It is deemed preferable to use a Bayesian Approach when the data obtained from the sensors are limited and it is difficult to obtain many measurements or it would be very costly, thus the problem of the lack of data can be solved by introducing a priori estimations of data. To infer the prior data, it is assumed that the roofs of the buildings are specified as smooth, and for that purpose local entropy has been implemented. In addition to the a priori estimations, GNSS RTK measurements have been collected in the field which are used as check points to assess the quality of the DSMs and to validate the merging result. The model has been applied in the West-End of Glasgow containing different kinds of buildings, such as flat roofed and hipped roofed buildings. Both quantitative and qualitative methods have been employed to validate the merged DSM. The validation results have shown that the model was successfully able to improve the quality of the DSMs and improving some characteristics such as the roof surfaces, which consequently led to better representations. In addition to that, the developed model has been compared with the well established Maximum Likelihood model and showed similar quantitative statistical results and better qualitative results. Although the proposed model has been applied on DSMs that were derived from satellite imagery, it can be applied to any other sourced DSMs.

  5. MERGING DIGITAL SURFACE MODELS IMPLEMENTING BAYESIAN APPROACHES

    Directory of Open Access Journals (Sweden)

    H. Sadeq

    2016-06-01

    Full Text Available In this research different DSMs from different sources have been merged. The merging is based on a probabilistic model using a Bayesian Approach. The implemented data have been sourced from very high resolution satellite imagery sensors (e.g. WorldView-1 and Pleiades. It is deemed preferable to use a Bayesian Approach when the data obtained from the sensors are limited and it is difficult to obtain many measurements or it would be very costly, thus the problem of the lack of data can be solved by introducing a priori estimations of data. To infer the prior data, it is assumed that the roofs of the buildings are specified as smooth, and for that purpose local entropy has been implemented. In addition to the a priori estimations, GNSS RTK measurements have been collected in the field which are used as check points to assess the quality of the DSMs and to validate the merging result. The model has been applied in the West-End of Glasgow containing different kinds of buildings, such as flat roofed and hipped roofed buildings. Both quantitative and qualitative methods have been employed to validate the merged DSM. The validation results have shown that the model was successfully able to improve the quality of the DSMs and improving some characteristics such as the roof surfaces, which consequently led to better representations. In addition to that, the developed model has been compared with the well established Maximum Likelihood model and showed similar quantitative statistical results and better qualitative results. Although the proposed model has been applied on DSMs that were derived from satellite imagery, it can be applied to any other sourced DSMs.

  6. In-depth analysis of drivers' merging behavior and rear-end crash risks in work zone merging areas.

    Science.gov (United States)

    Weng, Jinxian; Xue, Shan; Yang, Ying; Yan, Xuedong; Qu, Xiaobo

    2015-04-01

    This study investigates the drivers' merging behavior and the rear-end crash risk in work zone merging areas during the entire merging implementation period from the time of starting a merging maneuver to that of completing the maneuver. With the merging traffic data from a work zone site in Singapore, a mixed probit model is developed to describe the merging behavior, and two surrogate safety measures including the time to collision (TTC) and deceleration rate to avoid the crash (DRAC) are adopted to compute the rear-end crash risk between the merging vehicle and its neighboring vehicles. Results show that the merging vehicle has a bigger probability of completing a merging maneuver quickly under one of the following situations: (i) the merging vehicle moves relatively fast; (ii) the merging lead vehicle is a heavy vehicle; and (iii) there is a sizable gap in the adjacent through lane. Results indicate that the rear-end crash risk does not monotonically increase as the merging vehicle speed increases. The merging vehicle's rear-end crash risk is also affected by the vehicle type. There is a biggest increment of rear-end crash risk if the merging lead vehicle belongs to a heavy vehicle. Although the reduced remaining distance to work zone could urge the merging vehicle to complete a merging maneuver quickly, it might lead to an increased rear-end crash risk. Interestingly, it is found that the rear-end crash risk could be generally increased over the elapsed time after the merging maneuver being triggered. Copyright © 2015 Elsevier Ltd. All rights reserved.

  7. Changes in thunderstorm characteristics due to feeder cloud merging

    Science.gov (United States)

    Sinkevich, Andrei A.; Krauss, Terrence W.

    2014-06-01

    Cumulus cloud merging is a complex dynamical and microphysical process in which two convective cells merge into a single cell. Previous radar observations and numerical simulations have shown a substantial increase in the maximum area, maximum echo top and maximum reflectivity as a result of the merging process. Although the qualitative aspects of merging have been well documented, the quantitative effects on storm properties remain less defined. Therefore, a statistical assessment of changes in storm characteristics due to merging is of importance. Further investigation into the effects of cloud merging on precipitation flux (Pflux) in a statistical manner provided the motivation for this study in the Asir region of Saudi Arabia. It was confirmed that merging has a strong effect on storm development in this region. The data analysis shows that an increase in the median of the distribution of maximum reflectivity was observed just after merging and was equal to 3.9 dBZ. A detailed analysis of the individual merge cases compared the merged storm Pflux and mass to the sum of the individual Feeder and Storm portions just before merging for each case. The merged storm Pflux increased an average of 106% over the 20-min period after merging, and the mass increased on average 143%. The merged storm clearly became larger and more severe than the sum of the two parts prior to merging. One consequence of this study is that any attempts to evaluate the precipitation enhancement effects of cloud seeding must also include the issue of cloud mergers because merging can have a significant effect on the results.

  8. ISOTOPE METHODS IN HOMOGENEOUS CATALYSIS.

    Energy Technology Data Exchange (ETDEWEB)

    BULLOCK,R.M.; BENDER,B.R.

    2000-12-01

    The use of isotope labels has had a fundamentally important role in the determination of mechanisms of homogeneously catalyzed reactions. Mechanistic data is valuable since it can assist in the design and rational improvement of homogeneous catalysts. There are several ways to use isotopes in mechanistic chemistry. Isotopes can be introduced into controlled experiments and followed where they go or don't go; in this way, Libby, Calvin, Taube and others used isotopes to elucidate mechanistic pathways for very different, yet important chemistries. Another important isotope method is the study of kinetic isotope effects (KIEs) and equilibrium isotope effect (EIEs). Here the mere observation of where a label winds up is no longer enough - what matters is how much slower (or faster) a labeled molecule reacts than the unlabeled material. The most careti studies essentially involve the measurement of isotope fractionation between a reference ground state and the transition state. Thus kinetic isotope effects provide unique data unavailable from other methods, since information about the transition state of a reaction is obtained. Because getting an experimental glimpse of transition states is really tantamount to understanding catalysis, kinetic isotope effects are very powerful.

  9. Specific acid catalysis and Lewis acid catalysis of Diels–Alder reactions in aqueous media

    NARCIS (Netherlands)

    Mubofu, Egid B.; Engberts, Jan B.F.N.

    2004-01-01

    A comparative study of specific acid catalysis and Lewis acid catalysis of Diels–Alder reactions between dienophiles (1, 4 and 6) and cyclopentadiene (2) in water and mixed aqueous media is reported. The reactions were performed in water with copper(II) nitrate as the Lewis acid catalyst whereas

  10. Specific acid catalysis and Lewis acid catalysis of Diels-Alder reactions in aqueous media

    NARCIS (Netherlands)

    Mubofu, E.B.; Engberts, J.B.F.N.

    A comparative study of specific acid catalysis and Lewis acid catalysis of Diells-Alder reactions between dienophiles (1, 4 and 6) and cyclopentadiene (2) in water and mixed aqueous media is reported. The reactions were performed in water with copper(II) nitrate as the Lewis acid catalyst whereas

  11. Nano catalysis: Academic Discipline and Industrial Realities

    International Nuclear Information System (INIS)

    Olveira, S.; Forster, S.P.; Seeger, S.

    2014-01-01

    Nano technology plays a central role in both academic research and industrial applications. Nano enabled products are not only found in consumer markets, but also importantly in business to business markets (B2B). One of the oldest application areas of nano technology is nano catalysis—an excellent example for such a B2 B market. Several existing reviews illustrate the scientific developments in the field of nano catalysis. The goal of the present review is to provide an up-to-date picture of academic research and to extend this picture by an industrial and economic perspective. We therefore conducted an extensive search on several scientific databases and we further analyzed more than 1,500 nano catalysis-related patents and numerous market studies. We found that scientists today are able to prepare nano catalysts with superior characteristics regarding activity, selectivity, durability, and recoverability, which will contribute to solve current environmental, social, and industrial problems. In industry, the potential of nano catalysis is recognized, clearly reflected by the increasing number of nano catalysis-related patents and products on the market. The current nano catalysis research in academic and industrial laboratories will therefore enable a wealth of future applications in the industry

  12. DETECTION OF FLUX EMERGENCE, SPLITTING, MERGING, AND CANCELLATION OF NETWORK FIELD. I. SPLITTING AND MERGING

    Energy Technology Data Exchange (ETDEWEB)

    Iida, Y.; Yokoyama, T. [Department of Earth and Planetary Science, University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Hagenaar, H. J. [Lockheed Martin Advanced Technology Center, Org. ADBS, Building 252, 3251 Hanover Street, Palo Alto, CA 94304 (United States)

    2012-06-20

    Frequencies of magnetic patch processes on the supergranule boundary, namely, flux emergence, splitting, merging, and cancellation, are investigated through automatic detection. We use a set of line-of-sight magnetograms taken by the Solar Optical Telescope (SOT) on board the Hinode satellite. We found 1636 positive patches and 1637 negative patches in the data set, whose time duration is 3.5 hr and field of view is 112'' Multiplication-Sign 112''. The total numbers of magnetic processes are as follows: 493 positive and 482 negative splittings, 536 positive and 535 negative mergings, 86 cancellations, and 3 emergences. The total numbers of emergence and cancellation are significantly smaller than those of splitting and merging. Further, the frequency dependence of the merging and splitting processes on the flux content are investigated. Merging has a weak dependence on the flux content with a power-law index of only 0.28. The timescale for splitting is found to be independent of the parent flux content before splitting, which corresponds to {approx}33 minutes. It is also found that patches split into any flux contents with the same probability. This splitting has a power-law distribution of the flux content with an index of -2 as a time-independent solution. These results support that the frequency distribution of the flux content in the analyzed flux range is rapidly maintained by merging and splitting, namely, surface processes. We suggest a model for frequency distributions of cancellation and emergence based on this idea.

  13. Homogeneous and heterogeneous photoredox-catalyzed hydroxymethylation of ketones and keto esters: catalyst screening, chemoselectivity and dilution effects

    Directory of Open Access Journals (Sweden)

    Axel G. Griesbeck

    2014-05-01

    Full Text Available The homogeneous titanium- and dye-catalyzed as well as the heterogeneous semiconductor particle-catalyzed photohydroxymethylation of ketones by methanol were investigated in order to evaluate the most active photocatalyst system. Dialkoxytitanium dichlorides are the most efficient species for chemoselective hydroxymethylation of acetophenone as well as other aromatic and aliphatic ketones. Pinacol coupling is the dominant process for semiconductor catalysis and ketone reduction dominates the Ti(OiPr4/methanol or isopropanol systems. Application of dilution effects on the TiO2 catalysis leads to an increase in hydroxymethylation at the expense of the pinacol coupling.

  14. Opportunities for Merging Chemical and Biological Synthesis

    Science.gov (United States)

    Wallace, Stephen; Balskus, Emily P.

    2014-01-01

    Organic chemists and metabolic engineers use largely orthogonal technologies to access small molecules like pharmaceuticals and commodity chemicals. As the use of biological catalysts and engineered organisms for chemical production grows, it is becoming increasingly evident that future efforts for chemical manufacture will benefit from the integration and unified expansion of these two fields. This review will discuss approaches that combine chemical and biological synthesis for small molecule production. We highlight recent advances in combining enzymatic and non-enzymatic catalysis in vitro, discuss the application of design principles from organic chemistry for engineering non-biological reactivity into enzymes, and describe the development of biocompatible chemistry that can be interfaced with microbial metabolism. PMID:24747284

  15. Sustainable green catalysis by supported metal nanoparticles.

    Science.gov (United States)

    Fukuoka, Atsushi; Dhepe, Paresh L

    2009-01-01

    The recent progress of sustainable green catalysis by supported metal nanoparticles is described. The template synthesis of metal nanoparticles in ordered porous materials is studied for the rational design of heterogeneous catalysts capable of high activity and selectivity. The application of these materials in green catalytic processes results in a unique activity and selectivity arising from the concerted effect of metal nanoparticles and supports. The high catalytic performances of Pt nanoparticles in mesoporous silica is reported. Supported metal catalysts have also been applied to biomass conversion by heterogeneous catalysis. Additionally, the degradation of cellulose by supported metal catalysts, in which bifunctional catalysis of acid and metal plays the key role for the hydrolysis and reduction of cellulose, is also reported. Copyright 2009 The Japan Chemical Journal Forum and Wiley Periodicals, Inc.

  16. Green chemistry by nano-catalysis

    KAUST Repository

    Polshettiwar, Vivek

    2010-01-01

    Nano-materials are important in many diverse areas, from basic research to various applications in electronics, biochemical sensors, catalysis and energy. They have emerged as sustainable alternatives to conventional materials, as robust high surface area heterogeneous catalysts and catalyst supports. The nano-sized particles increase the exposed surface area of the active component of the catalyst, thereby enhancing the contact between reactants and catalyst dramatically and mimicking the homogeneous catalysts. This review focuses on the use of nano-catalysis for green chemistry development including the strategy of using microwave heating with nano-catalysis in benign aqueous reaction media which offers an extraordinary synergistic effect with greater potential than these three components in isolation. To illustrate the proof-of-concept of this "green and sustainable" approach, representative examples are discussed in this article. © 2010 The Royal Society of Chemistry.

  17. Quantum catalysis : the modelling of catalytic transition states

    NARCIS (Netherlands)

    Hall, M.B.; Margl, P.; Naray-Szabo, G.; Schramm, Vern; Truhlar, D.G.; Santen, van R.A.; Warshel, A.; Whitten, J.L.; Truhlar, D.G.; Morokuma, K.

    1999-01-01

    A review with 101 refs.; we present an introduction to the computational modeling of transition states for catalytic reactions. We consider both homogeneous catalysis and heterogeneous catalysis, including organometallic catalysts, enzymes, zeolites and metal oxides, and metal surfaces. We summarize

  18. Competing role of catalysis-coagulation and catalysis-fragmentation in kinetic aggregation behaviours

    International Nuclear Information System (INIS)

    Li Xiao-Dong; Lin Zhen-Quan; Song Mei-Xia; Ke Jian-Hong

    2010-01-01

    We propose a kinetic aggregation model where species A aggregates evolve by the catalysis-coagulation and the catalysis-fragmentation, while the catalyst aggregates of the same species B or C perform self-coagulation processes. By means of the generalized Smoluchowski rate equation based on the mean-field assumption, we study the kinetic behaviours of the system with the catalysis-coagulation rate kernel K(i,j;l) ∝ l ν and the catalysis-fragmentation rate kernel F(i,j;l) ∝ l μ , where l is the size of the catalyst aggregate, and ν and μ are two parameters reflecting the dependence of the catalysis reaction on the size of the catalyst aggregate. The relation between the values of parameters ν and μ reflects the competing roles between the two catalysis processes in the kinetic evolution of species A. It is found that the competing roles of the catalysis-coagulation and catalysis-fragmentation in the kinetic aggregation behaviours are not determined simply by the relation between the two parameters ν and μ, but also depend on the values of these two parameters. When ν > μ and ν ≥ 0, the kinetic evolution of species A is dominated by the catalysis-coagulation and its aggregate size distribution a k (t) obeys the conventional or generalized scaling law; when ν k (t) approaches the scale-free form; and in other cases, a balance is established between the two competing processes at large times and a k (t) obeys a modified scaling law. (cross-disciplinary physics and related areas of science and technology)

  19. ISOON + SOLIS: Merging the Data Products

    Science.gov (United States)

    Radick, R.; Dalrymple, N.; Mozer, J.; Wiborg, P.; Harvey, J.; Henney, C.; Neidig, D.

    2005-05-01

    The combination of AFRL's ISOON and NSO's SOLIS offers significantly greater capability than the individual instruments. We are working toward merging the SOLIS and ISOON data products in a single central facility. The ISOON system currently includes both an observation facility and a remote analysis center (AC). The AC is capable of receiving data from both the ISOON observation facility as well as external sources. It archives the data and displays corrected images and time-lapse animations. The AC has a large number of digital tools that can be applied to solar images to provide quantitative information quickly and easily. Because of its convenient tools and ready archival capability, the ISOON AC is a natural place to merge products from SOLIS and ISOON. We have completed a preliminary integration of the ISOON and SOLIS data products. Eventually, we intend to distribute viewing stations to various users and academic institutions, install the AC software tools at a number of user locations, and publish ISOON/SOLIS data products jointly on a common web page. In addition, SOLIS data products, separately, are and will continue to be fully available on the NSO,s Digital Library and SOLIS web pages, and via the Virtual Solar Observatory. This work is being supported by the National Science Foundation and the Air Force Office of Scientific Research.

  20. Star Formation in Merging Galaxies Using FIRE

    Science.gov (United States)

    Perez, Adrianna; Hung, Chao-Ling; Naiman, Jill; Moreno, Jorge; Hopkins, Philip

    2018-01-01

    Galaxy interactions and mergers are efficient mechanisms to birth stars at rates that are significantly higher than found in our Milky Way galaxy. The Kennicut-Schmidt (KS) relation is an empirical relationship between the star-forming rate and gas surface densities of galaxies (Schmidt 1959; Kennicutt 1998). Although most galaxies follow the KS relation, the high levels of star formation in galaxy mergers places them outside of this otherwise tight relationship. The goal of this research is to analyze the gas content and star formation of simulated merging galaxies. Our work utilizes the Feedback In Realistic Environments (FIRE) model (Hopkins et al., 2014). The FIRE project is a high-resolution cosmological simulation that resolves star-forming regions and incorporates stellar feedback in a physically realistic way. In this work, we have noticed a significant increase in the star formation rate at first and second passage, when the two black holes of each galaxy approach one other. Next, we will analyze spatially resolved star-forming regions over the course of the interacting system. Then, we can study when and how the rates that gas converts into stars deviate from the standard KS. These analyses will provide important insights into the physical mechanisms that regulate star formation of normal and merging galaxies and valuable theoretical predictions that can be used to compare with current and future observations from ALMA or the James Webb Space Telescope.

  1. Electron-ion recombination in merged beams

    International Nuclear Information System (INIS)

    Wolf, A.; Habs, D.; Lampert, A.; Neumann, R.; Schramm, U.; Schuessler, T.; Schwalm, D.

    1993-01-01

    Detailed studies of recombination processes between electrons and highly charged ions have become possible by recent improvements of merged-beams experiments. We discuss in particular measurements with stored cooled ion beams at the Test Storage Ring (TSR) in Heidelberg. The cross section of dielectronic recombination was measured with high energy resolution for few-electron systems up to the nuclear charge of Cu at a relative energy up to 2.6 keV. At low energy (∼0.1 eV) total recombination rates of several ions were measured and compared with calculated radiative recombination rates. Laser-stimulated recombination of protons and of C 6+ ions was investigated as a function of the photon energy using visible radiation. Both the total recombination rates and the stimulated recombination spectra indicate that in spite of the short interaction time in merged beams, also collisional capture of electrons into weakly bound levels (related to three-body recombination) could be important

  2. Aeroacoustics of T-junction merging flow.

    Science.gov (United States)

    Lam, G C Y; Leung, R C K; Tang, S K

    2013-02-01

    This paper reports a numerical study of the aeroacoustics of merging flow at T-junction. The primary focus is to elucidate the acoustic generation by the flow unsteadiness. The study is conducted by performing direct aeroacoustic simulation approach, which solves the unsteady compressible Navier-Stokes equations and the perfect gas equation of state simultaneously using the conservation element and solution element method. For practical flows, the Reynolds number based on duct width is usually quite high (>10(5)). In order to properly account for the effects of flow turbulence, a large eddy simulation methodology together with a wall modeling derived from the classical logarithm wall law is adopted. The numerical simulations are performed in two dimensions and the acoustic generation physics at different ratios of side-branch to main duct flow velocities VR (=0.5,0.67,1.0,2.0) are studied. Both the levels of unsteady interactions of merging flow structures and the efficiency of acoustic generation are observed to increase with VR. Based on Curle's analogy, the major acoustic source is found to be the fluctuating wall pressure induced by the flow unsteadiness occurred in the downstream branch. A scaling between the wall fluctuating force and the efficiency of the acoustic generation is also derived.

  3. Next-Generation Catalysis for Renewables: Combining Enzymatic with Inorganic Heterogeneous Catalysis for Bulk Chemical Production

    DEFF Research Database (Denmark)

    Vennestrøm, Peter Nicolai Ravnborg; Christensen, C.H.; Pedersen, S.

    2010-01-01

    chemical platform under different conditions than those conventionally employed. Indeed, new process and catalyst concepts need to be established. Both enzymatic catalysis (biocatalysis) and heterogeneous inorganic catalysis are likely to play a major role and, potentially, be combined. One type...... of combination involves one-pot cascade catalysis with active sites from bio- and inorganic catalysts. In this article the emphasis is placed specifically on oxidase systems involving the coproduction of hydrogen peroxide, which can be used to create new in situ collaborative oxidation reactions for bulk...

  4. A molecular view of heterogeneous catalysis

    DEFF Research Database (Denmark)

    Christensen, Claus H.; Nørskov, Jens Kehlet

    2008-01-01

    The establishment of a molecular view of heterogeneous catalysis has been hampered for a number of reasons. There are, however, recent developments, which show that we are now on the way towards reaching a molecular-scale picture of the way solids work as catalysts. By a combination of new...... by enabling a rational design of new catalysts. We illustrate this important development in heterogeneous catalysis by highlighting recent examples of catalyst systems for which it has been possible to achieve such a detailed understanding. In particular, we emphasize examples where this progress has made...

  5. Keynotes in energy-related catalysis

    CERN Document Server

    Kaliaguine, S

    2011-01-01

    Catalysis by solid acids, which includes (modified) zeolites, is of special relevance to energy applications. Acid catalysis is highly important in modern petroleum refining operations - large-scale processes such as fluid catalytic cracking, catalytic reforming, alkylation and olefin oligomerization rely on the transformation of hydrocarbons by acid catalysts. (Modified) zeolites are therefore essential for the improvement of existing processes and for technical innovations in the conversion of crude. There can be little doubt that zeolite-based catalysts will play a major role in the futu

  6. Heterogeneous catalysis at nanoscale for energy applications

    CERN Document Server

    Tao, Franklin (Feng); Kamat, Prashant V

    2015-01-01

    This book presents both the fundamentals concepts and latest achievements of a field that is growing in importance since it represents a possible solution for global energy problems.  It focuses on an atomic-level understanding of heterogeneous catalysis involved in important energy conversion processes. It presents a concise picture for the entire area of heterogeneous catalysis with vision at the atomic- and nano- scales, from synthesis, ex-situ and in-situ characterization, catalytic activity and selectivity, to mechanistic understanding based on experimental exploration and theoretical si

  7. Catalysis by nonmetals rules for catalyst selection

    CERN Document Server

    Krylov, Oleg V

    1970-01-01

    Catalysis by Non-metals: Rules of Catalyst Selection presents the development of scientific principles for the collection of catalysts. It discusses the investigation of the mechanism of chemosorption and catalysis. It addresses a series of properties of solid with catalytic activity. Some of the topics covered in the book are the properties of a solid and catalytic activity in oxidation-reduction reactions; the difference of electronegativities and the effective charges of atoms; the role of d-electrons in the catalytic properties of a solid; the color of solids; and proton-acid and proton-ba

  8. µ-reactors for Heterogeneous Catalysis

    DEFF Research Database (Denmark)

    Jensen, Robert

    is described in detail. Since heating and temperature measurement is an extremely important point in heterogeneous catalysis an entire chapter is dedicated to this subject. Three different types of heaters have been implemented and tested both for repeatability and homogeneity of the heating as well...

  9. Heterogeneous catalysis in highly sensitive microreactors

    DEFF Research Database (Denmark)

    Olsen, Jakob Lind

    This thesis present a highly sensitive silicon microreactor and examples of its use in studying catalysis. The experimental setup built for gas handling and temperature control for the microreactor is described. The implementation of LabVIEW interfacing for all the experimental parts makes...

  10. Supported ionic liquid-phase (SILP) catalysis

    DEFF Research Database (Denmark)

    Riisager, Anders; Fehrmann, Rasmus; Wasserscheid, P.

    2005-01-01

    The concept of supported ionic liquid-phase (SILP) catalysis has been demonstrated for gas- and liquid-phase continuous fixed-bed reactions using rhodium phosphine catalyzed hydroformylation of propene and 1-octene as examples. The nature of the support had important influence on both the catalytic...

  11. Rate tracer studies of heterogeneous catalysis

    Energy Technology Data Exchange (ETDEWEB)

    Happel, J; Kiang, S

    1977-10-01

    An analysis is presented of the extent to which parameters involved in transient tracing of isotopic species in heterogeneous catalysis can be determined by experiments in which tracer concentrations are measured as a function of time. Different treatments for open and closed systems with the over-all reaction at equilibrium or irreversible were developed.

  12. Transition metal catalysis in confined spaces

    NARCIS (Netherlands)

    Leenders, S.H.A.M.

    2016-01-01

    Chemical reactions are required for the conversion of feedstocks to valuable materials, such as different types of plastics, pharmaceutical ingredients and advanced materials. In order to facilitate the conversion of these feedstocks to a wide array of products, catalysis plays a prominent role.

  13. Asymmetric Aminalization via Cation-Binding Catalysis

    DEFF Research Database (Denmark)

    Park, Sang Yeon; Liu, Yidong; Oh, Joong Suk

    2018-01-01

    Asymmetric cation-binding catalysis, in principle, can generate "chiral" anionic nucleophiles, where the counter cations are coordinated within chiral environments. Nitrogen-nucleophiles are intrinsically basic, therefore, its use as nucleophiles is often challenging and limiting the scope of the...

  14. Merging Platform Ecosystems in Technology Acquisitions

    DEFF Research Database (Denmark)

    Dowie, Jamie; Henningsson, Stefan; Kude, Thomas

    2017-01-01

    of the merging companies. Given the increasing importance of platforms and value co-creation with third-party providers for companies making technology acquisitions, we complement existing literature by reframing the analysis of technology acquisitions to include the merger of the broader partner ecosystems....... Specifically, we draw on theories of ecosystem governance to analyze how ecosystem tensions unfolded during the ecosystem merger and how the acquirer governed these tensions in SAP SE’s acquisition of the e-commerce provider Hybris AG. Our findings suggest that the governance of ecosystem tensions...... is an important aspect of managing technology acquisitions. We identify the pre-acquisition relation between the acquired company’s ecosystem partners and the acquirer as an important context factor for explaining how a partner company is exposed to the ecosystem tensions during the merger....

  15. Will the urge to merge continue?

    International Nuclear Information System (INIS)

    Gobert, W.A.

    2001-01-01

    A review of oil and gas markets was presented along with mergers and acquisitions activity. The objective of the exercise was to determine if the current trend of mergers within the oil industry will continue. The review of oil and gas markets included a historical look at crude oil and natural gas prices as well as on industry activity as a whole. A series of economic indicator graphs demonstrate that buyers wallets are full, oil and gas prices have beat the estimates, purchase prices have inflated and shareholders continue to sell at a discount. This information has led the author to conclude that the trend to merge will definitely continue. 2 tabs., 18 figs

  16. Merging Educational Finance Reform and Desegregation Goals

    Directory of Open Access Journals (Sweden)

    Deborah M. Kazal-Thresher

    1993-06-01

    Full Text Available Educational finance reforms and desegregation have both sought to address inequities in educational opportunities for minorities and low income families. The recent methods of addressing desegregation issues have tended to focus on attaining racial balance rather than educational quality, however. This paper explores how desegregation goals can be merged with educational finance reform to more systematically address educational quality in schools serving low income and minority populations. By moving toward centralized control over school financing, the inequity of school outcomes that are based on unequal school resources can be reduced. In addition, state determined expenditures when combined with desegregation monies, would meet the original intention of desegregation funds by clearly providing add-on monies for additional services for minority children, while at the same time, creating a better monitoring mechanism.

  17. Merging and energy exchange between optical filaments

    Energy Technology Data Exchange (ETDEWEB)

    Georgieva, D. A., E-mail: dgeorgieva@tu-sofia.bg [Faculty of Applied Mathematics and Computer Science, Technical University of Sofia, 8 Kliment Ohridski Blvd., 1000 Sofia (Bulgaria); Kovachev, L. M. [Institute of Electronics, Bulgarian Academy of Sciences, 72 Tzarigradcko Chaussee Blvd., 1784 Sofia (Bulgaria)

    2015-10-28

    We investigate nonlinear interaction between collinear femtosecond laser pulses with power slightly above the critical for self-focusing P{sub cr} trough the processes of cross-phase modulation (CPM) and degenerate four-photon parametric mixing (FPPM). When there is no initial phase difference between the pulses we observe attraction between pulses due to CPM. The final result is merging between the pulses in a single filament with higher power. By method of moments it is found that the attraction depends on the distance between the pulses and has potential character. In the second case we study energy exchange between filaments. This process is described through FPPM scheme and requests initial phase difference between the waves.

  18. Merging Iron Catalysis and Biocatalysis-Iron Carbonyl Complexes as Efficient Hydrogen Autotransfer Catalysts in Dynamic Kinetic Resolutions

    KAUST Repository

    El-Sepelgy, Osama

    2016-09-29

    A dual catalytic iron/lipase system has been developed and applied in the dynamic kinetic resolution of benzylic and aliphatic secondary alcohols. A detailed study of the Knölker-type iron complexes demonstrated the hydrogen autotransfer of alcohols to proceed under mild reaction conditions and allowed the combination with the enzymatic resolution. Different racemic alcohols were efficiently converted to chiral acetates in good yields and with excellent enantioselectivities. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

  19. Merging Iron Catalysis and Biocatalysis-Iron Carbonyl Complexes as Efficient Hydrogen Autotransfer Catalysts in Dynamic Kinetic Resolutions

    KAUST Repository

    El-Sepelgy, Osama; Alandini, Nurtalya; Rueping, Magnus

    2016-01-01

    A dual catalytic iron/lipase system has been developed and applied in the dynamic kinetic resolution of benzylic and aliphatic secondary alcohols. A detailed study of the Knölker-type iron complexes demonstrated the hydrogen autotransfer of alcohols to proceed under mild reaction conditions and allowed the combination with the enzymatic resolution. Different racemic alcohols were efficiently converted to chiral acetates in good yields and with excellent enantioselectivities. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

  20. Observations and Modeling of Merging Galaxy Clusters

    Science.gov (United States)

    Golovich, Nathan Ryan

    Context: Galaxy clusters grow hierarchically with continuous accretion bookended by major merging events that release immense gravitational potential energy (as much as ˜1065 erg). This energy creates an environment for rich astrophysics. Precise measurements of the dark matter halo, intracluster medium, and galaxy population have resulted in a number of important results including dark matter constraints and explanations of the generation of cosmic rays. However, since the timescale of major mergers (˜several Gyr) relegates observations of individual systems to mere snapshots, these results are difficult to understand under a consistent dynamical framework. While computationally expensive simulations are vital in this regard, the vastness of parameter space has necessitated simulations of idealized mergers that are unlikely to capture the full richness. Merger speeds, geometries, and timescales each have a profound consequential effect, but even these simple dynamical properties of the mergers are often poorly understood. A method to identify and constrain the best systems for probing the rich astrophysics of merging clusters is needed. Such a method could then be utilized to prioritize observational follow up and best inform proper exploration of dynamical phase space. Task: In order to identify and model a large number of systems, in this dissertation, we compile an ensemble of major mergers each containing radio relics. We then complete a pan-chromatic study of these 29 systems including wide field optical photometry, targeted optical spectroscopy of member galaxies, radio, and X-ray observations. We use the optical observations to model the galaxy substructure and estimate line of sight motion. In conjunction with the radio and X-ray data, these substructure models helped elucidate the most likely merger scenario for each system and further constrain the dynamical properties of each system. We demonstrate the power of this technique through detailed analyses

  1. Determination of Onramp Weaving Length for Resolving Merging Dilemma

    Directory of Open Access Journals (Sweden)

    Chiu Liu

    2012-03-01

    Full Text Available It is physically known that onramp merging may turn out to be difficult if the onramp (weaving/merging length is too short because a driver under certain driving circumstances may find that either merging ahead or merging behind a neighboring vehicle on the adjacent highway lane cannot be completed. Various existing guidelines or design manuals provide no clear physical understanding and explanations to the design onramp weaving length but often based on evolved empirical experiences. By integrating human factors, vehicle dynamic characteristics, roadway surface condition, and the onramp weaving design into a single unified analytic framework, the onramp length required for a driver to merge into the highway traffic successfully is determined exactly with formulas and physical solutions to avoid the merging dilemma and enhance driving safety at highway interchanges. The design onramp weaving length is examined and evaluated with various foreseeable merging scenarios and physical examples. This analytic framework sheds light on the understanding of the onramp weaving the first time strictly on a physical human-vehicle-roadway interaction setting. Practitioners can easily apply these user friendly formulae and equations derived from the unified framework to calculate the onramp weaving length to resolve the merging dilemma and enhance driving safety for any highway interchanges.

  2. Learning to merge search results for efficient Distributed Information Retrieval

    NARCIS (Netherlands)

    Tjin-Kam-Jet, Kien; Hiemstra, Djoerd

    2010-01-01

    Merging search results from different servers is a major problem in Distributed Information Retrieval. We used Regression-SVM and Ranking-SVM which would learn a function that merges results based on information that is readily available: i.e. the ranks, titles, summaries and URLs contained in the

  3. Merging startup experiments on the UTST spherical tokamak

    International Nuclear Information System (INIS)

    Yamada, Takuma; Kamio, Shuji; Imazawa, Ryota

    2010-01-01

    The University of Tokyo Spherical Tokamak (UTST) was constructed to explore the formation of ultrahigh-beta spherical tokamak (ST) plasmas using double null plasma merging. The main feature of the UTST is that the poloidal field coils are located outside the vacuum vessel to demonstrate startup in a reactor-relevant situation. Initial operations used partially completed power supplies to investigate the appropriate conditions for plasma merging. The plasma current of the merged ST reached 100 kA when the central solenoid coil was used to assist plasma formation. Merging of two ST plasmas through magnetic reconnection was successfully observed using two-dimensional pickup coil arrays, which directly measure the toroidal and axial magnetic fields inside the UTST vacuum vessel. The resistivity of the current sheet was found to be anomalously high during merging. (author)

  4. Experiments on CT plasma merging in the CTCC-1

    International Nuclear Information System (INIS)

    Watanabe, K.; Ikegami, K.; Nishikawa, M.; Ozaki, A.; Satomi, N.; Uyama, T.

    1982-01-01

    A compact toroid (CT) plasma merging experiment has been tried preliminarily in the CTCC-1 experiment as a method for further-heating of CT, on producing two CT plasmas in the flux conserver successively. Two CT plasmas were observed really to merge with each other in the flux conserver. In the merging process, it is found that the field reconnection of surface magnetic field lines of CT is completed until 30 μs after the second CT injection, but magnetic field lines around the center of CT merge slowly, taking about 100 μs. Experimental results indicate that merging of CT results in doubled addition of toroidal fluxes and no-addition of poloidal fluxes

  5. Merging Galaxy Clusters: Analysis of Simulated Analogs

    Science.gov (United States)

    Nguyen, Jayke; Wittman, David; Cornell, Hunter

    2018-01-01

    The nature of dark matter can be better constrained by observing merging galaxy clusters. However, uncertainty in the viewing angle leads to uncertainty in dynamical quantities such as 3-d velocities, 3-d separations, and time since pericenter. The classic timing argument links these quantities via equations of motion, but neglects effects of nonzero impact parameter (i.e. it assumes velocities are parallel to the separation vector), dynamical friction, substructure, and larger-scale environment. We present a new approach using n-body cosmological simulations that naturally incorporate these effects. By uniformly sampling viewing angles about simulated cluster analogs, we see projected merger parameters in the many possible configurations of a given cluster. We select comparable simulated analogs and evaluate the likelihood of particular merger parameters as a function of viewing angle. We present viewing angle constraints for a sample of observed mergers including the Bullet cluster and El Gordo, and show that the separation vectors are closer to the plane of the sky than previously reported.

  6. Contact Binaries on Their Way Towards Merging

    Science.gov (United States)

    Gazeas, K.

    2015-07-01

    Contact binaries are the most frequently observed type of eclipsing star system. They are small, cool, low-mass binaries belonging to a relatively old stellar population. They follow certain empirical relationships that closely connect a number of physical parameters with each other, largely because of constraints coming from the Roche geometry. As a result, contact binaries provide an excellent test of stellar evolution, specifically for stellar merger scenarios. Observing campaigns by many authors have led to the cataloging of thousands of contact binaries and enabled statistical studies of many of their properties. A large number of contact binaries have been found to exhibit extraordinary behavior, requiring follow-up observations to study their peculiarities in detail. For example, a doubly-eclipsing quadruple system consisting of a contact binary and a detached binary is a highly constrained system offering an excellent laboratory to test evolutionary theories for binaries. A new observing project was initiated at the University of Athens in 2012 in order to investigate the possible lower limit for the orbital period of binary systems before coalescence, prior to merging.

  7. Approaches to single-nanoparticle catalysis.

    Science.gov (United States)

    Sambur, Justin B; Chen, Peng

    2014-01-01

    Nanoparticles are among the most important industrial catalysts, with applications ranging from chemical manufacturing to energy conversion and storage. Heterogeneity is a general feature among these nanoparticles, with their individual differences in size, shape, and surface sites leading to variable, particle-specific catalytic activity. Assessing the activity of individual nanoparticles, preferably with subparticle resolution, is thus desired and vital to the development of efficient catalysts. It is challenging to measure the activity of single-nanoparticle catalysts, however. Several experimental approaches have been developed to monitor catalysis on single nanoparticles, including electrochemical methods, single-molecule fluorescence microscopy, surface plasmon resonance spectroscopy, X-ray microscopy, and surface-enhanced Raman spectroscopy. This review focuses on these experimental approaches, the associated methods and strategies, and selected applications in studying single-nanoparticle catalysis with chemical selectivity, sensitivity, or subparticle spatial resolution.

  8. ELECTROCHEMICAL PROMOTED CATALYSIS: TOWARDS PRACTICAL UTILIZATION

    Directory of Open Access Journals (Sweden)

    DIMITRIOS TSIPLAKIDES

    2008-07-01

    Full Text Available Electrochemical promotion (EP of catalysis has already been recognized as “a valuable development in catalytic research” (J. Pritchard, 1990 and as “one of the most remarkable advances in electrochemistry since 1950” (J. O’M. Bockris, 1996. Laboratory studies have clearly elucidated the phenomenology of electrochemical promotion and have proven that EP is a general phenomenon at the interface of catalysis and electrochemistry. The major progress toward practical utilization of EP is surveyed in this paper. The focus is given on the electropromotion of industrial ammonia synthesis catalyst, the bipolar EP and the development of a novel monolithic electropromoted reactor (MEPR in conjunction with the electropromotion of thin sputtered metal films. Future perspectives of electrochemical promotion applications in the field of hydrogen technologies are discussed.

  9. Symmetry and asymmetry in mandelate racemase catalysis

    International Nuclear Information System (INIS)

    Whitman, C.P.; Hegeman, G.D.; Cleland, W.W.; Kenyon, G.L.

    1985-01-01

    Kinetic properties of mandelate racemase catalysis (Vmax, Km, deuterium isotope effects, and pH profiles) were all measured in both directions by the circular dichroic assay of Sharp. These results, along with those of studying interactions of mandelate racemase with resolved, enantiomeric competitive inhibitors [(R)- and (S)-alpha-phenylglycerates], indicate a high degree of symmetry in both binding and catalysis. Racemization of either enantiomer of mandelate in D 2 O did not show an overshoot region of molecular ellipticity in circular dichroic measurements upon approach to equilibrium. Both the absence of such an overshoot region and the high degree of kinetic symmetry are consistent with a one-base acceptor mechanism for mandelate racemase. On the other hand, results of irreversible inhibition with partially resolved, enantiomeric affinity labels [(R)- and (S)-alpha-phenylglycidates] reveal a ''functional asymmetry'' at the active site. Mechanistic proposals, consistent with these results, are presented

  10. USD Catalysis Group for Alternative Energy

    Energy Technology Data Exchange (ETDEWEB)

    Hoefelmeyer, James D.; Koodali, Ranjit; Sereda, Grigoriy; Engebretson, Dan; Fong, Hao; Puszynski, Jan; Shende, Rajesh; Ahrenkiel, Phil

    2012-03-13

    The South Dakota Catalysis Group (SDCG) is a collaborative project with mission to develop advanced catalysts for energy conversion with two primary goals: (1) develop photocatalytic systems in which polyfunctionalized TiO2 are the basis for hydrogen/oxygen synthesis from water and sunlight (solar fuels group), (2) develop new materials for hydrogen utilization in fuel cells (fuel cell group). In tandem, these technologies complete a closed chemical cycle with zero emissions.

  11. Impact of Secondary Interactions in Asymmetric Catalysis

    OpenAIRE

    Frölander, Anders

    2007-01-01

    This thesis deals with secondary interactions in asymmetric catalysis and their impact on the outcome of catalytic reactions. The first part revolves around the metal-catalyzed asymmetric allylic alkylation reaction and how interactions within the catalyst affect the stereochemistry. An OH–Pd hydrogen bond in Pd(0)–π-olefin complexes of hydroxy-containing oxazoline ligands was identified by density functional theory computations and helped to rationalize the contrasting results obtained emplo...

  12. Confined catalysis under two-dimensional materials

    OpenAIRE

    Li, Haobo; Xiao, Jianping; Fu, Qiang; Bao, Xinhe

    2017-01-01

    Small spaces in nanoreactors may have big implications in chemistry, because the chemical nature of molecules and reactions within the nanospaces can be changed significantly due to the nanoconfinement effect. Two-dimensional (2D) nanoreactor formed under 2D materials can provide a well-defined model system to explore the confined catalysis. We demonstrate a general tendency for weakened surface adsorption under the confinement of graphene overlayer, illustrating the feasible modulation of su...

  13. Hybrid nuclear reactors and muon catalysis

    International Nuclear Information System (INIS)

    Petrov, Yu.

    1983-01-01

    Three methods are described of the conversion of isotope 238 U to 239 Pu by neutron capture in fast breeder reactors, in the breeding blanket of hybrid thermonuclear reactors using neutrons generated by fusion and electronuclear breeding in which the target is bombarded with 1 GeV protons. Their possible use in power production is discussed. Another prospective energy source is the use of muon catalysis in the fusion of deuterium and tritium nuclei. (J.P.)

  14. Nanoscale Advances in Catalysis and Energy Applications

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yimin; Somorjai, Gabor A.

    2010-05-12

    In this perspective, we present an overview of nanoscience applications in catalysis, energy conversion, and energy conservation technologies. We discuss how novel physical and chemical properties of nanomaterials can be applied and engineered to meet the advanced material requirements in the new generation of chemical and energy conversion devices. We highlight some of the latest advances in these nanotechnologies and provide an outlook at the major challenges for further developments.

  15. Predictive Modeling in Actinide Chemistry and Catalysis

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Ping [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-05-16

    These are slides from a presentation on predictive modeling in actinide chemistry and catalysis. The following topics are covered in these slides: Structures, bonding, and reactivity (bonding can be quantified by optical probes and theory, and electronic structures and reaction mechanisms of actinide complexes); Magnetic resonance properties (transition metal catalysts with multi-nuclear centers, and NMR/EPR parameters); Moving to more complex systems (surface chemistry of nanomaterials, and interactions of ligands with nanoparticles); Path forward and conclusions.

  16. Catalysis in micellar and macromoleular systems

    CERN Document Server

    Fendler, Janos

    1975-01-01

    Catalysis in Micellar and Macromolecular Systems provides a comprehensive monograph on the catalyses elicited by aqueous and nonaqueous micelles, synthetic and naturally occurring polymers, and phase-transfer catalysts. It delineates the principles involved in designing appropriate catalytic systems throughout. Additionally, an attempt has been made to tabulate the available data exhaustively. The book discusses the preparation and purification of surfactants; the physical and chemical properties of surfactants and micelles; solubilization in aqueous micellar systems; and the principles of

  17. Numerical Investigation of Merged and Non-merged Flame of a Twin Cavity Annular Trapped Vortex Combustor

    Directory of Open Access Journals (Sweden)

    Pravendra Kumar

    2016-09-01

    Full Text Available : The present work is focused to characterize numerically the merged and non-merged flame emanating from the cavities in downstream of twin cavity Annular Trapped Vortex Combustor (ATVC.The isotherm corresponding to the auto-ignition temperature is used to locate the merging point of the flame in the mainstream region along the combustor length. In present study, the cavity flame is said to be merged only if this isotherm corresponding to self-ignition temperature of methane is located within 20 percentage of the combustor length from aft wall of cavities. It is interesting to note that on increasing the power loading parameter (PLP in mainstream for a constant power loading parameter ratio (outer to inner cavity, the merging point gets shifted towards the cavity aft-wall. This leads to the reduction of combustor length and subsequent reduction in overall weight of the gas turbine engine.

  18. Neutrons for Catalysis: A Workshop on Neutron Scattering Techniques for Studies in Catalysis

    International Nuclear Information System (INIS)

    Overbury, Steven H.; Coates, Leighton; Herwig, Kenneth W.; Kidder, Michelle

    2011-01-01

    This report summarizes the Workshop on Neutron Scattering Techniques for Studies in Catalysis, held at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory (ORNL) on September 16 and 17, 2010. The goal of the Workshop was to bring experts in heterogeneous catalysis and biocatalysis together with neutron scattering experimenters to identify ways to attack new problems, especially Grand Challenge problems in catalysis, using neutron scattering. The Workshop locale was motivated by the neutron capabilities at ORNL, including the High Flux Isotope Reactor (HFIR) and the new and developing instrumentation at the SNS. Approximately 90 researchers met for 1 1/2 days with oral presentations and breakout sessions. Oral presentations were divided into five topical sessions aimed at a discussion of Grand Challenge problems in catalysis, dynamics studies, structure characterization, biocatalysis, and computational methods. Eleven internationally known invited experts spoke in these sessions. The Workshop was intended both to educate catalyst experts about the methods and possibilities of neutron methods and to educate the neutron community about the methods and scientific challenges in catalysis. Above all, it was intended to inspire new research ideas among the attendees. All attendees were asked to participate in one or more of three breakout sessions to share ideas and propose new experiments that could be performed using the ORNL neutron facilities. The Workshop was expected to lead to proposals for beam time at either the HFIR or the SNS; therefore, it was expected that each breakout session would identify a few experiments or proof-of-principle experiments and a leader who would pursue a proposal after the Workshop. Also, a refereed review article will be submitted to a prominent journal to present research and ideas illustrating the benefits and possibilities of neutron methods for catalysis research.

  19. Neutrons for Catalysis: A Workshop on Neutron Scattering Techniques for Studies in Catalysis

    Energy Technology Data Exchange (ETDEWEB)

    Overbury, Steven {Steve} H [ORNL; Coates, Leighton [ORNL; Herwig, Kenneth W [ORNL; Kidder, Michelle [ORNL

    2011-10-01

    This report summarizes the Workshop on Neutron Scattering Techniques for Studies in Catalysis, held at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory (ORNL) on September 16 and 17, 2010. The goal of the Workshop was to bring experts in heterogeneous catalysis and biocatalysis together with neutron scattering experimenters to identify ways to attack new problems, especially Grand Challenge problems in catalysis, using neutron scattering. The Workshop locale was motivated by the neutron capabilities at ORNL, including the High Flux Isotope Reactor (HFIR) and the new and developing instrumentation at the SNS. Approximately 90 researchers met for 1 1/2 days with oral presentations and breakout sessions. Oral presentations were divided into five topical sessions aimed at a discussion of Grand Challenge problems in catalysis, dynamics studies, structure characterization, biocatalysis, and computational methods. Eleven internationally known invited experts spoke in these sessions. The Workshop was intended both to educate catalyst experts about the methods and possibilities of neutron methods and to educate the neutron community about the methods and scientific challenges in catalysis. Above all, it was intended to inspire new research ideas among the attendees. All attendees were asked to participate in one or more of three breakout sessions to share ideas and propose new experiments that could be performed using the ORNL neutron facilities. The Workshop was expected to lead to proposals for beam time at either the HFIR or the SNS; therefore, it was expected that each breakout session would identify a few experiments or proof-of-principle experiments and a leader who would pursue a proposal after the Workshop. Also, a refereed review article will be submitted to a prominent journal to present research and ideas illustrating the benefits and possibilities of neutron methods for catalysis research.

  20. Controllable Catalysis with Nanoparticles: Bimetallic Alloy Systems and Surface Adsorbates

    KAUST Repository

    Chen, Tianyou

    2016-05-16

    Transition metal nanoparticles are privileged materials in catalysis due to their high specific surface areas and abundance of active catalytic sites. While many of these catalysts are quite useful, we are only beginning to understand the underlying catalytic mechanisms. Opening the “black box” of nanoparticle catalysis is essential to achieve the ultimate goal of catalysis by design. In this Perspective we highlight recent work addressing the topic of controlled catalysis with bimetallic alloy and “designer” adsorbate-stabilized metal nanoparticles.

  1. Controllable Catalysis with Nanoparticles: Bimetallic Alloy Systems and Surface Adsorbates

    KAUST Repository

    Chen, Tianyou; Rodionov, Valentin

    2016-01-01

    Transition metal nanoparticles are privileged materials in catalysis due to their high specific surface areas and abundance of active catalytic sites. While many of these catalysts are quite useful, we are only beginning to understand the underlying catalytic mechanisms. Opening the “black box” of nanoparticle catalysis is essential to achieve the ultimate goal of catalysis by design. In this Perspective we highlight recent work addressing the topic of controlled catalysis with bimetallic alloy and “designer” adsorbate-stabilized metal nanoparticles.

  2. Controlling inclusive cross sections in parton shower + matrix element merging

    International Nuclear Information System (INIS)

    Plaetzer, Simon

    2012-11-01

    We propose an extension of matrix element plus parton shower merging at tree level to preserve inclusive cross sections obtained from the merged and showered sample. Implementing this constraint generates approximate next-to-leading order (NLO) contributions similar to the LoopSim approach. We then show how full NLO, or in principle even higher order, corrections can be added consistently, including constraints on inclusive cross sections to account for yet missing parton shower accuracy at higher logarithmic order. We also show how NLO accuracy below the merging scale can be obtained.

  3. Controlling inclusive cross sections in parton shower + matrix element merging

    Energy Technology Data Exchange (ETDEWEB)

    Plaetzer, Simon

    2012-11-15

    We propose an extension of matrix element plus parton shower merging at tree level to preserve inclusive cross sections obtained from the merged and showered sample. Implementing this constraint generates approximate next-to-leading order (NLO) contributions similar to the LoopSim approach. We then show how full NLO, or in principle even higher order, corrections can be added consistently, including constraints on inclusive cross sections to account for yet missing parton shower accuracy at higher logarithmic order. We also show how NLO accuracy below the merging scale can be obtained.

  4. Eosin Y photoredox catalyzed net redox neutral reaction for regiospecific annulation to 3-sulfonylindoles via anion oxidation of sodium sulfinate salts.

    Science.gov (United States)

    Rohokale, Rajendra S; Tambe, Shrikant D; Kshirsagar, Umesh A

    2018-01-24

    An eosin Y photoredox catalyzed net redox neutral process for 3-sulfonylindoles via the anionic oxidation of sodium sulfinate salts and its radical cascade cyclization with 2-alkynyl-azidoarenes was developed with visible light as a mediator. The reaction offers metal and oxidant/reductant free, visible light mediated vicinal sulfonamination of alkynes to 2-aryl/alkyl-3-sulfonylindoles and proceeds via the generation of a sulfur-centered radical through direct oxidation of the sulfinate anion by an excited photocatalyst with a reductive quenching cycle. The mild conditions, use of an organic dye as photo-catalyst, bench stability and easily accessible starting materials make the present approach green and attractive.

  5. Merged Land and Ocean Surface Temperature, Version 3.5

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The historical Merged Land-Ocean Surface Temperature Analysis (MLOST) is derived from two independent analyses, an Extended Reconstructed Sea Surface Temperature...

  6. 2013 NOAA Coastal California TopoBathy Merge Project

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This project merged recently collected topographic, bathymetric, and acoustic elevation data along the entire California coastline from approximately the 10 meter...

  7. Objectness Supervised Merging Algorithm for Color Image Segmentation

    Directory of Open Access Journals (Sweden)

    Haifeng Sima

    2016-01-01

    Full Text Available Ideal color image segmentation needs both low-level cues and high-level semantic features. This paper proposes a two-hierarchy segmentation model based on merging homogeneous superpixels. First, a region growing strategy is designed for producing homogenous and compact superpixels in different partitions. Total variation smoothing features are adopted in the growing procedure for locating real boundaries. Before merging, we define a combined color-texture histogram feature for superpixels description and, meanwhile, a novel objectness feature is proposed to supervise the region merging procedure for reliable segmentation. Both color-texture histograms and objectness are computed to measure regional similarities between region pairs, and the mixed standard deviation of the union features is exploited to make stop criteria for merging process. Experimental results on the popular benchmark dataset demonstrate the better segmentation performance of the proposed model compared to other well-known segmentation algorithms.

  8. Seamless-merging-oriented parallel inverse lithography technology

    International Nuclear Information System (INIS)

    Yang Yiwei; Shi Zheng; Shen Shanhu

    2009-01-01

    Inverse lithography technology (ILT), a promising resolution enhancement technology (RET) used in next generations of IC manufacture, has the capability to push lithography to its limit. However, the existing methods of ILT are either time-consuming due to the large layout in a single process, or not accurate enough due to simply block merging in the parallel process. The seamless-merging-oriented parallel ILT method proposed in this paper is fast because of the parallel process; and most importantly, convergence enhancement penalty terms (CEPT) introduced in the parallel ILT optimization process take the environment into consideration as well as environmental change through target updating. This method increases the similarity of the overlapped area between guard-bands and work units, makes the merging process approach seamless and hence reduces hot-spots. The experimental results show that seamless-merging-oriented parallel ILT not only accelerates the optimization process, but also significantly improves the quality of ILT.

  9. Satellite and gauge rainfall merging using geographically weighted regression

    Directory of Open Access Journals (Sweden)

    Q. Hu

    2015-05-01

    Full Text Available A residual-based rainfall merging scheme using geographically weighted regression (GWR has been proposed. This method is capable of simultaneously blending various satellite rainfall data with gauge measurements and could describe the non-stationary influences of geographical and terrain factors on rainfall spatial distribution. Using this new method, an experimental study on merging daily rainfall from the Climate Prediction Center Morphing dataset (CMOROH and gauge measurements was conducted for the Ganjiang River basin, in Southeast China. We investigated the capability of the merging scheme for daily rainfall estimation under different gauge density. Results showed that under the condition of sparse gauge density the merging rainfall scheme is remarkably superior to the interpolation using just gauge data.

  10. “ABBA” REVISITED: MERGING THE HORIZONS OF HISTORY AND ...

    African Journals Online (AJOL)

    ture of metaphors in terms of their rhetorical functions. The New Rhetoric pro- ... between literal and metaphorical in favour of the merging of another two ho- .... cently in The Dictionary of Classical Hebrew of the Hebrew Bible and the Dead.

  11. LP MOON MERGED TELEMETRY DATA V1.0

    Data.gov (United States)

    National Aeronautics and Space Administration — The Lunar Prospector merged telemetry data set is a result of comparing the two Lunar Prospector telemetry data streams and selecting one of them. The Lunar...

  12. Can double-peaked lines indicate merging effects in AGNs?

    Directory of Open Access Journals (Sweden)

    Popović L.Č.

    2000-01-01

    Full Text Available The influence of merging effects in the central part of an Active Galactic Nucleus (AGN on the emission spectral line shapes are discussed. We present a model of close binary Broad Line Region. The numerical experiments show that the merging effects can explain double peaked lines. The merging effects may also be present in the center of AGNs, although they emit slightly asymmetric as well as symmetric and relatively stable (in profile shape spectral lines. Depending on the black hole masses and their orbit elements such model may explain some of the line profile shapes observed in AGNs. This work shows that if one is looking for the merging effects in the central region as well as in the wide field structure of AGNs, he should first pay attention to objects which have double peaked lines.

  13. Merging Mixture Components for Cell Population Identification in Flow Cytometry

    Directory of Open Access Journals (Sweden)

    Greg Finak

    2009-01-01

    Full Text Available We present a framework for the identification of cell subpopulations in flow cytometry data based on merging mixture components using the flowClust methodology. We show that the cluster merging algorithm under our framework improves model fit and provides a better estimate of the number of distinct cell subpopulations than either Gaussian mixture models or flowClust, especially for complicated flow cytometry data distributions. Our framework allows the automated selection of the number of distinct cell subpopulations and we are able to identify cases where the algorithm fails, thus making it suitable for application in a high throughput FCM analysis pipeline. Furthermore, we demonstrate a method for summarizing complex merged cell subpopulations in a simple manner that integrates with the existing flowClust framework and enables downstream data analysis. We demonstrate the performance of our framework on simulated and real FCM data. The software is available in the flowMerge package through the Bioconductor project.

  14. On-the Fly Merging of Attitude Solutions

    DEFF Research Database (Denmark)

    Jørgensen, Peter Siegbjørn; Jørgensen, John Leif; Denver, Troelz

    2008-01-01

    Recent advances in autonomous attitude determination instrumentation enable even small satellites flying fully autonomous multi head star trackers providing full accurate and robust attitude information. Each sensor provides the full attitude information but for robustness and optimal usage...... of the available information, i.e. optimal accuracy, methods for merging such data should be investigated. The need for and desirability of attitude merging depends on the mission objective and available resources. To enable real-time attitude control and reduce requirements on download budget, on-board merging...... of attitude data will often be advantageous. This should be weighted against the need for post observation reconstruction of attitudes, especially needed when end products are sensitive to optimal attitude reconstruction. Instrument integrated merging algorithms will reduce the complexity of on-board AOCS...

  15. Surface Science Foundations of Catalysis and Nanoscience

    CERN Document Server

    Kolasinski, Kurt K

    2012-01-01

    Surface science has evolved from being a sub-field of chemistry or physics, and has now established itself as an interdisciplinary topic. Knowledge has developed sufficiently that we can now understand catalysis from a surface science perspective. No-where is the underpinning nature of surface science better illustrated than with nanoscience. Now in its third edition, this successful textbook aims to provide students with an understanding of chemical transformations and the formation of structures at surfaces. The chapters build from simple to more advanced principles with each featuring exerc

  16. Catalysis-enhanced strengthening of porous materials

    International Nuclear Information System (INIS)

    Sokolova, L.N.; Shchukin, E.D.; Burenkova, L.N.; Romanovskij, B.V.

    2000-01-01

    Change in the strength of compressed tablets of the catalyst on the basis of ZrO 2 (84 mass %) and Y 2 O 3 (16 mass %) after conducting the endothermal reaction of the methanol and ethanol dehydration at 700-800 deg C is studied. It is shown, that the key factor, determining the strengthening effect by 65-88% is not at all the reaction exothermal nature, which could lead to local heating of the catalyst surface. In reality significant increase in concentration of surface defects, as compared to the equilibrium at the given temperature is achieved on the account of conjugation of processes of catalysis and surface defects formation [ru

  17. Catalysis in electrochemistry: from fundamentals to strategies for fuel cell development

    National Research Council Canada - National Science Library

    Santos, Elizabeth; Schmickler, Wolfgang

    2011-01-01

    "Catalysis in Electrochemistry: From Fundamentals to Strategies for Fuel Cell Development is a modern, comprehensive reference work on catalysis in electrochemistry, including principles, methods, strategies, and applications...

  18. The nature of the active site in heterogeneous metal catalysis

    DEFF Research Database (Denmark)

    Nørskov, Jens Kehlet; Bligaard, Thomas; Larsen, Britt Hvolbæk

    2008-01-01

    This tutorial review, of relevance for the surface science and heterogeneous catalysis communities, provides a molecular-level discussion of the nature of the active sites in metal catalysis. Fundamental concepts such as "Bronsted-Evans-Polanyi relations'' and "volcano curves'' are introduced...

  19. UV Catalysis, Cyanotype Photography, and Sunscreens

    Science.gov (United States)

    Lawrence, Glen D.; Fishelson, Stuart

    1999-09-01

    This laboratory experiment is intended for a chemistry course for non-science majors. The experiment utilizes one of the earliest photographic processes, the cyanotype process, to demonstrate UV catalysis of chemical reactions. In addition to making photographic prints from negatives, the process can be used to test the effectiveness of sunscreens and the relative efficacy of the SPF (sun protection factor) rating of sunscreens. This is an inexpensive process, requiring solutions of ammonium ferric citrate and potassium ferricyanide, with options to use hydrogen peroxide and ammonium hydroxide solutions. Students can prepare their own UV-sensitized paper with the indicated chemicals and watch the photographic image appear as it is exposed to sunlight or fluorescent UV lamps in a light box designed for use in this experiment. The laboratory experiment should stimulate discussion of UV catalysis, photographic processes and photochemistry, sunscreens, and UV damage to biological organisms. The chemicals used are relatively nontoxic, and the procedure is simple enough to be used by groups of diverse ages and abilities.

  20. Merging a Pair of Supermassive Black Holes

    Science.gov (United States)

    Kohler, Susanna

    2016-10-01

    When galaxies merge, the supermassive black holes (SMBHs) at the galaxies centers are thought to coalesce, forming a new, larger black hole. But can this merger process take place on timescales short enough that we could actually observe it? Results from a new simulation suggests that it can!When Galaxies CollideThese stills demonstrate the time evolution of the galaxy merger after the beginning of the authors simulation (starting from z=3.6). The red and blue dots mark the positions of the SMBHs. [Adapted from Khan et al. 2016]At present, its not well understood how the merger of two SMBHs proceeds from the merger of their host galaxies. Whats more, there are concerns about whether the SMBHs can coalesce on reasonable timescales; in many simulations and models, the inspiral of these behemoths stalls out when they are about a parsec apart, in whats known as the final parsec problem.Why are these mergers poorly understood? Modeling them from the initial interactions of the host galaxies all the way down to the final coalescence of their SMBHs in a burst of gravitational waves is notoriously complicated, due to the enormous range of scales and different processes that must be accounted for.But in a recent study, a team of scientists led by Fazeel Khan (Institute of Space Technology in Pakistan) has presented a simulation that successfully manages to track the entire merger making it the first multi-scale simulation to model the complete evolution of an SMBH binary that forms within a cosmological galaxy merger.Stages of aSimulationKhan and collaborators tackled the challenges of this simulation by using a multi-tiered approach.Beginning with the output of a cosmological hydrodynamical simulation, the authors select a merger of two typical massive galaxies at z=3.6 and use this as the starting point for their simulation. They increase the resolution and add in two supermassive black holes, one at the center of each galaxy.They then continue to evolve the galaxies

  1. Individual Subjective Initiative Merge Model Based on Cellular Automaton

    Directory of Open Access Journals (Sweden)

    Yin-Jie Xu

    2013-01-01

    Full Text Available The merge control models proposed for work zones are classified into two types (Hard Control Merge (HCM model and Soft Control Merge (SCM model according to their own control intensity and are compared with a new model, called Individual Subjective Initiative Merge (ISIM model, which is based on the linear lane-changing probability strategy in the merging area. The attention of this paper is paid to the positive impact of the individual subjective initiative for the whole traffic system. Three models (ISIM, HCM, and SCM are established and compared with each other by two order parameters, that is, system output and average vehicle travel time. Finally, numerical results show that both ISIM and SCM perform better than HCM. Compared with SCM, the output of ISIM is 20 vehicles per hour higher under the symmetric input condition and is more stable under the asymmetric input condition. Meanwhile, the average travel time of ISIM is 2000 time steps less under the oversaturated input condition.

  2. Observations in the Earth's magnetotail relating to magnetic merging

    International Nuclear Information System (INIS)

    Hones, E.W. Jr.

    1976-01-01

    For more than a decade there has been growing conviction that the burst of energy from a solar flare is first stored in magnetic fields and is then released rapidly by magnetic field annihilation (magnetic merging). There has also been recognition that magnetic merging may be responsible for the energy release manifested in auroral phenomena at the Earth. The most substantial evidence that magnetic merging does indeed occur in the Earth's magnetosphere and causes the auroral phenomena is provided by recent observations, in the magnetotail, of very rapid (approximately 500 km s -1 ) tailward, then earthward, flow of plasma during magnetospheric substorms. The observations, made with the Vela and IMP satellites, reveal also that the component of the tail magnetic field perpendicular to the tail neutral sheet changes polarity at the time of the reversal of plasma flow. These features are interpreted as indicative of passage of a magnetic neutral line, at which magnetic merging is proceeding, past the observing satellite. This paper describes an example of such observations made with IMP 6. It is anticipated that such systematic measurements of the plasma, energetic particles and magnetic field in the neighborhood of the passing neutral line on many such occasions will provide a general understanding of the magnetic merging process which can be applied to studies of solar flares and other astrophysical phenomena. (Auth.)

  3. Reconnection and merging of positive streamers in air

    Energy Technology Data Exchange (ETDEWEB)

    Nijdam, S; Geurts, C G C; Van Veldhuizen, E M; Ebert, U, E-mail: s.nijdam@tue.n [Department of Applied Physics, Eindhoven University of Technology, PO Box 513, 5600 MB Eindhoven (Netherlands)

    2009-02-21

    Pictures show that streamer or sprite discharge channels emerging from the same electrode sometimes seem to reconnect or merge though their heads carry electric charge of the same polarity; one might therefore suspect that reconnections are an artefact of the two-dimensional projection in the pictures. Here we use stereo photography to investigate the full three-dimensional structure of such events. We analyse reconnection, possibly an electrostatic effect in which a late thin streamer reconnects to an earlier thick streamer channel, and merging, a suggested photoionization effect in which two simultaneously propagating streamer heads merge into one new streamer. We use four different anode geometries (one tip, two tips, two asymmetric protrusions in a plate and a wire), placed 40 mm above a flat cathode plate in ambient air. A positive high voltage pulse is applied to the anode, creating a positive corona discharge. This discharge is studied with a fast ICCD camera, in many cases combined with optics to enable stereoscopic imaging. We find that reconnections as defined above occur frequently. Merging on the other hand was only observed at a pressure of 25 mbar and a tip separation of 2 mm, i.e. for a reduced tip distance of p{center_dot}d = 50 {mu}m bar. In this case the full width at half maximum of the streamer channel is more than 10 times as large as the tip separation. At higher pressures or with a wire anode, merging was not observed.

  4. Reconnection and merging of positive streamers in air

    International Nuclear Information System (INIS)

    Nijdam, S; Geurts, C G C; Van Veldhuizen, E M; Ebert, U

    2009-01-01

    Pictures show that streamer or sprite discharge channels emerging from the same electrode sometimes seem to reconnect or merge though their heads carry electric charge of the same polarity; one might therefore suspect that reconnections are an artefact of the two-dimensional projection in the pictures. Here we use stereo photography to investigate the full three-dimensional structure of such events. We analyse reconnection, possibly an electrostatic effect in which a late thin streamer reconnects to an earlier thick streamer channel, and merging, a suggested photoionization effect in which two simultaneously propagating streamer heads merge into one new streamer. We use four different anode geometries (one tip, two tips, two asymmetric protrusions in a plate and a wire), placed 40 mm above a flat cathode plate in ambient air. A positive high voltage pulse is applied to the anode, creating a positive corona discharge. This discharge is studied with a fast ICCD camera, in many cases combined with optics to enable stereoscopic imaging. We find that reconnections as defined above occur frequently. Merging on the other hand was only observed at a pressure of 25 mbar and a tip separation of 2 mm, i.e. for a reduced tip distance of p·d = 50 μm bar. In this case the full width at half maximum of the streamer channel is more than 10 times as large as the tip separation. At higher pressures or with a wire anode, merging was not observed.

  5. New and future developments in catalysis catalysis for remediation and environmental concerns

    CERN Document Server

    Suib, Steven L

    2013-01-01

    New and Future Developments in Catalysis is a package of seven books that compile the latest ideas concerning alternate and renewable energy sources and the role that catalysis plays in converting new renewable feedstock into biofuels and biochemicals. Both homogeneous and heterogeneous catalysts and catalytic processes will be discussed in a unified and comprehensive approach. There will be extensive cross-referencing within all volumes. The various sources of environmental pollution are the theme of this volume. The volume lists all current environmentally friendly catalytic chemical processes used for environmental remediation and critically compares their economic viability. Offers in-depth coverage of all catalytic topics of current interest and outlines future challenges and research areas A clear and visual description of all parameters and conditions, enabling the reader to draw conclusions for a particular case Outlines the catalytic processes applicable to energy generation and design of green proce...

  6. A Numerical Study of Vortex and Precipitating Cloud Merging in Middle Latitudes

    Institute of Scientific and Technical Information of China (English)

    PING Fan; LUO Zhe-Xian; JU Jian-Hua

    2006-01-01

    @@ We mainly focus on the study of precipitating cloud merging associated with vortex merging. The vortex and precipitating cloud merging are simulated by the cloud resolving model from 0000 21 to 1800 23 July 2003. The results show that the model well simulates vortex circulation associated with precipitating clouds. It is also proven that the vortex merging follows the precipitating cloud merging although vortices show the spatial and temporal differences. The convection vorticity vector is introduced to describe the merging processes. Two merging cases are identified during the 42-h simulation and are studied.

  7. Scaled beam merging experiment for heavy ion inertial fusion

    Directory of Open Access Journals (Sweden)

    P. A. Seidl

    2003-09-01

    Full Text Available Transverse beam combining is a cost-saving option employed in many designs for heavy ion fusion drivers. However, the resultant transverse phase space dilution must be minimized so as not to sacrifice focusability at the target. A prototype combining experiment has been completed employing four 3-mA Cs^{+} beams injected at 160 keV. The focusing elements upstream of the merge consist of four quadrupoles and a final combined-function element (quadrupole and dipole. Following the merge, the resultant single beam is transported in a single alternating gradient channel where the subsequent evolution of the distribution function is diagnosed. The results are in fair agreement with particle-in-cell simulations. They indicate that for some heavy ion fusion driver designs, the phase space dilution from merging is acceptable.

  8. Microbial electro-catalysis in fuel cell

    International Nuclear Information System (INIS)

    Dumas, Claire

    2007-01-01

    Microbial fuel cells (MFC) are devices that ensure the direct conversion of organic matter into electricity using bacterial bio-films as the catalysts of the electrochemical reactions. This study aims at improving the comprehension of the mechanisms involved in electron transfer pathways between the adhered bacteria and the electrodes. This optimization of the MFC power output could be done, for example, in exploring and characterizing various electrode materials. The electrolysis experiments carried out on Geobacter sulfurreducens deal with the microbial catalysis of the acetate oxidation, on the one hand, and the catalysis of the fumarate reduction on the other hand. On the anodic side, differences in current densities appeared on graphite, DSA R and stainless steel (8 A/m 2 , 5 A/m 2 and 0.7 A/m 2 respectively). These variations were explained more by materials roughness differences rather than their nature. Impedance spectroscopy study shows that the electro-active bio-film developed on stainless steel does not seem to modify the evolution of the stainless steel oxide layer, only the imposed potential remains determining. On the cathodic side, stainless steel sustained current densities more than twenty times higher than those obtained with graphite electrodes. The adhesion study of G. sulfurreducens on various materials in a flow cell, suggests that the bio-films resist to the hydrodynamic constraints and are not detached under a shear stress threshold value. The installation of two MFC prototypes, one in a sea station and the other directly in Genoa harbour (Italy) confirms some results obtained in laboratory and were promising for a MFC scale-up. (author) [fr

  9. Prebiotic RNA Synthesis by Montmorillonite Catalysis

    Directory of Open Access Journals (Sweden)

    Sohan Jheeta

    2014-08-01

    Full Text Available This review summarizes our recent findings on the role of mineral salts in prebiotic RNA synthesis, which is catalyzed by montmorillonite clay minerals. The clay minerals not only catalyze the synthesis of RNA but also facilitate homochiral selection. Preliminary data of these findings have been presented at the “Horizontal Gene Transfer and the Last Universal Common Ancestor (LUCA” conference at the Open University, Milton Keynes, UK, 5–6 September 2013. The objective of this meeting was to recognize the significance of RNA in LUCA. We believe that the prebiotic RNA synthesis from its monomers must have been a simple process. As a first step, it may have required activation of the 5'-end of the mononucleotide with a leaving group, e.g., imidazole in our model reaction (Figure 1. Wide ranges of activating groups are produced from HCN under plausible prebiotic Earth conditions. The final step is clay mineral catalysis in the presence of mineral salts to facilitate selective production of functional RNA. Both the clay minerals and mineral salts would have been abundant on early Earth. We have demonstrated that while montmorillonite (pH 7 produced only dimers from its monomers in water, addition of sodium chloride (1 M enhanced the chain length multifold, as detected by HPLC. The effect of monovalent cations on RNA synthesis was of the following order: Li+ > Na+ > K+. A similar effect was observed with the anions, enhancing catalysis in the following order: Cl− > Br− > I−. The montmorillonite-catalyzed RNA synthesis was not affected by hydrophobic or hydrophilic interactions. We thus show that prebiotic synthesis of RNA from its monomers was a simple process requiring only clay minerals and a small amount of salt.

  10. Incorporating Edge Information into Best Merge Region-Growing Segmentation

    Science.gov (United States)

    Tilton, James C.; Pasolli, Edoardo

    2014-01-01

    We have previously developed a best merge region-growing approach that integrates nonadjacent region object aggregation with the neighboring region merge process usually employed in region growing segmentation approaches. This approach has been named HSeg, because it provides a hierarchical set of image segmentation results. Up to this point, HSeg considered only global region feature information in the region growing decision process. We present here three new versions of HSeg that include local edge information into the region growing decision process at different levels of rigor. We then compare the effectiveness and processing times of these new versions HSeg with each other and with the original version of HSeg.

  11. Program Merges SAR Data on Terrain and Vegetation Heights

    Science.gov (United States)

    Siqueira, Paul; Hensley, Scott; Rodriguez, Ernesto; Simard, Marc

    2007-01-01

    X/P Merge is a computer program that estimates ground-surface elevations and vegetation heights from multiple sets of data acquired by the GeoSAR instrument [a terrain-mapping synthetic-aperture radar (SAR) system that operates in the X and bands]. X/P Merge software combines data from X- and P-band digital elevation models, SAR backscatter magnitudes, and interferometric correlation magnitudes into a simplified set of output topographical maps of ground-surface elevation and tree height.

  12. Density functional theory studies of transition metal nanoparticles in catalysis

    DEFF Research Database (Denmark)

    Greeley, Jeffrey Philip; Rankin, Rees; Zeng, Zhenhua

    2013-01-01

    Periodic Density Functional Theory calculations are capable of providing powerful insights into the structural, energetics, and electronic phenomena that underlie heterogeneous catalysis on transition metal nanoparticles. Such calculations are now routinely applied to single crystal metal surfaces...... and to subnanometer metal clusters. Descriptions of catalysis on truly nanosized structures, however, are generally not as well developed. In this talk, I will illustrate different approaches to analyzing nanocatalytic phenomena with DFT calculations. I will describe case studies from heterogeneous catalysis...... and electrocatalysis, in which single crystal models are combined with Wulff construction-based ideas to produce descriptions of average nanocatalyst behavior. Then, I will proceed to describe explicitly DFT-based descriptions of catalysis on truly nanosized particles (

  13. Bridging heterogeneous and homogeneous catalysis concepts, strategies, and applications

    CERN Document Server

    Li, Can

    2014-01-01

    This unique handbook fills the gap in the market for an up-to-date work that links both homogeneous catalysis applied to organic reactions and catalytic reactions on surfaces of heterogeneous catalysts.

  14. Nanostructured Membranes for Green Synthesis of Nanoparticles and Enzyme Catalysis

    Science.gov (United States)

    Macroporous membranes functionalized with ionizable macromolecules provide promising applications in toxic metal capture at high capacity, nanoparticle synthesis, and catalysis. Our low‐pressure membrane approach is marked by reaction and separation selectivity and their tunabili...

  15. Nanostructured Membranes for Enzyme Catalysis and Green Synthesis of Nanoparticles

    Science.gov (United States)

    Macroporous membranes functionalized with ionizable macromolecules provide promising applications in toxic metal capture at high capacity, nanoparticle synthesis, and catalysis. Our low-pressure membrane approach is marked by reaction and separation selectivity and their tunabil...

  16. Estimate-Merge-Technique-based algorithms to track an underwater ...

    Indian Academy of Sciences (India)

    D V A N Ravi Kumar

    2017-07-04

    Jul 4, 2017 ... In this paper, two novel methods based on the Estimate Merge Technique ... mentioned advantages of the proposed novel methods is shown by carrying out Monte Carlo simulation in .... equations are converted to sequential equations to make ... estimation error and low convergence time) at feasibly high.

  17. Cascading Constrained 2-D Arrays using Periodic Merging Arrays

    DEFF Research Database (Denmark)

    Forchhammer, Søren; Laursen, Torben Vaarby

    2003-01-01

    We consider a method for designing 2-D constrained codes by cascading finite width arrays using predefined finite width periodic merging arrays. This provides a constructive lower bound on the capacity of the 2-D constrained code. Examples include symmetric RLL and density constrained codes...

  18. Creating an Excellence Oriented Post-merged Organisational ...

    African Journals Online (AJOL)

    This article specifically focuses on the importance of a structured approach to the implementation of employee engagement strategies in creating a post-merged organisational culture of excellent work performance. Theoretical insights from existing literature illustrate how a structured approach to the implementation of ...

  19. A Merging Algorithm for Aerosol Size Distribution from Multiple Instruments

    Czech Academy of Sciences Publication Activity Database

    Ondráček, Jakub; Ždímal, Vladimír; Smolík, Jiří; Lazaridis, M.

    2009-01-01

    Roč. 199, 1-4 (2009), s. 219-233 ISSN 0049-6979 Grant - others:MTKD(XE) CT-2004-513849 Institutional research plan: CEZ:AV0Z40720504 Keywords : aerosols * merging particle size distribution * multilognormal model Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.676, year: 2009

  20. Simulations of Merging Helion Bunches on the AGS Injection Porch

    Energy Technology Data Exchange (ETDEWEB)

    Gardner, C. J. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.

    2014-08-29

    During the setup of helions for the FY2014 RHIC run it was discovered that the standard scheme for merging bunches on the AGS injection porch required an injection kicker pulse shorter than what was available. To overcome this difficulty, K. Zeno proposed and developed an interesting and unusual alternative which uses RF harmonic numbers 12, 4, 2 (rather than the standard 8, 4, 2) to merge 8 helion bunches into 2. In this note we carry out simulations that illustrate how the alternative scheme works and how it compares with the standard scheme. This is done in Sections 13 and 14. A scheme in which 6 bunches are merged into 1 is simulated in Section 15. This may be useful if more helions per merged bunch are needed in future runs. General formulae for the simulations are given in Sections 9 through 12. For completeness, Sections 1 through 8 give a derivation of the turn-by-turn equations of longitudinal motion at constant magnetic field. The derivation is based on the work of MacLachlan. The reader may wish to skip over these Sections and start with Section 9.

  1. Vertical vs. Horizontal Integration: Pre-emptive Merging.

    OpenAIRE

    Colangelo, Giuseppe

    1995-01-01

    Preemption plays a crucial role in arms merger decisions. The author studies whether and under which circumstances preemptive merging occurs in vertically related industries. He finds that vertical mergers often preempt horizontal mergers and are dominant outcomes. Preempting the threat of a detrimental horizontal integration may be the main reason for vertically integrating. Copyright 1995 by Blackwell Publishing Ltd.

  2. Merging the Internet and Hypermedia in the English Language Arts.

    Science.gov (United States)

    Reed, W. Michael; Wells, John G.

    1997-01-01

    Discussion of hypermedia and computer-mediated communication focuses on a project that merges a language arts Internet resource with a hypermedia-based knowledge construction approach to learning. Highlights include constructing a HyperCard-based program on Shakespeare's "Hamlet," gophers and search engines, downloading, collaborative…

  3. Simulations of Merging Helion Bunches on the AGS Injection Porch

    International Nuclear Information System (INIS)

    Gardner, C. J.

    2014-01-01

    During the setup of helions for the FY2014 RHIC run it was discovered that the standard scheme for merging bunches on the AGS injection porch required an injection kicker pulse shorter than what was available. To overcome this difficulty, K. Zeno proposed and developed an interesting and unusual alternative which uses RF harmonic numbers 12, 4, 2 (rather than the standard 8, 4, 2) to merge 8 helion bunches into 2. In this note we carry out simulations that illustrate how the alternative scheme works and how it compares with the standard scheme. This is done in Sections 13 and 14. A scheme in which 6 bunches are merged into 1 is simulated in Section 15. This may be useful if more helions per merged bunch are needed in future runs. General formulae for the simulations are given in Sections 9 through 12. For completeness, Sections 1 through 8 give a derivation of the turn-by-turn equations of longitudinal motion at constant magnetic field. The derivation is based on the work of MacLachlan. The reader may wish to skip over these Sections and start with Section 9.

  4. Interaction protocols for cooperative merging and lane reduction scenarios

    NARCIS (Netherlands)

    Semsar-Kazerooni, E.; Ploeg, J.

    2015-01-01

    This paper presents the interaction protocols developed for execution of two common scenarios in daily traffic using cooperative automated vehicles. The first proposed scenario addresses merging of a (semi-)automated car on a highway within a platoon of (semi-)automated vehicles. The second scenario

  5. Resource Based Multi Agent Plan Merging : Framework and application

    NARCIS (Netherlands)

    De Weerdt, M.M.; Van der Krogt, R.P.J.; Witteveen, C.

    2003-01-01

    We discuss a resource-based planning framework where agents are able to merge plans by exchanging resources. In this framework, plans are specified as structured objects composed of resource consuming and resource producing processes (actions). A plan itself can also be conceived as a process

  6. An eMERGE Clinical Center at Partners Personalized Medicine

    Directory of Open Access Journals (Sweden)

    Jordan W. Smoller

    2016-01-01

    Full Text Available The integration of electronic medical records (EMRs and genomic research has become a major component of efforts to advance personalized and precision medicine. The Electronic Medical Records and Genomics (eMERGE network, initiated in 2007, is an NIH-funded consortium devoted to genomic discovery and implementation research by leveraging biorepositories linked to EMRs. In its most recent phase, eMERGE III, the network is focused on facilitating implementation of genomic medicine by detecting and disclosing rare pathogenic variants in clinically relevant genes. Partners Personalized Medicine (PPM is a center dedicated to translating personalized medicine into clinical practice within Partners HealthCare. One component of the PPM is the Partners Healthcare Biobank, a biorepository comprising broadly consented DNA samples linked to the Partners longitudinal EMR. In 2015, PPM joined the eMERGE Phase III network. Here we describe the elements of the eMERGE clinical center at PPM, including plans for genomic discovery using EMR phenotypes, evaluation of rare variant penetrance and pleiotropy, and a novel randomized trial of the impact of returning genetic results to patients and clinicians.

  7. Inclusive cross sections in ME+PS merging

    International Nuclear Information System (INIS)

    Plaetzer, Simon

    2013-07-01

    We discuss an extension of matrix element plus parton shower merging at leading and next-to-leading order. The algorithm does preserve inclusive cross sections at the respective input order. This constraint avoids potentially large logarithmic contributions, which would require approximate (N)NLO contributions to cancel against.

  8. Sampling, Splitting and Merging in Coinductive Stream Calculus

    NARCIS (Netherlands)

    M. Niqui (Milad); J.J.M.M. Rutten (Jan); C. Bolduc; J. Desharnais; B. Ktari

    2010-01-01

    textabstractWe study various operations for partitioning, projecting and merging streams of data. These operations are motivated by their use in dataflow programming and the stream processing languages. We use the framework of \\emph{stream calculus} and \\emph{stream circuits} for defining and

  9. Sampling, splitting and merging in coinductive stream calculus

    NARCIS (Netherlands)

    M. Niqui (Milad); J.J.M.M. Rutten (Jan)

    2009-01-01

    htmlabstractWe study various operations for partitioning, projecting and merging streams of data. These operations are motivated by their use in dataflow programming and the stream processing languages. We use the framework of stream calculus and stream circuits for defining and proving properties

  10. Merging research orientation with professional apprenticeship training through PBL

    DEFF Research Database (Denmark)

    Willert, Søren

    2012-01-01

    The paper discusses an ongoing process of merging two university-based teaching traditions. The two traditions are alike in that both share a basic commitment to PBL-related values. Differences refer (as stated in the paper’s title) to one tradition being relatively more research oriented, whereas...

  11. Simulations of Bunch Merging in a Beta Beam Decay Ring

    CERN Document Server

    Heinrich, Daniel Christopher; Chance, Antoine

    2011-01-01

    To further study neutrino oscillation properties a Beta Beam facility has been proposed. Beta decaying ions with high kinetic energy are stored in a storage ring ("Decay Ring") with straight sections to create pure focused (anti) electron neutrino beams. However to reach high sensitivity to neutrino oscillation parameters in the experiment the bunched beam intensity and duty cycle in the DR have to be optimized. The first CERN-based scenario, using 6He and 18Ne as neutrino sources, has been studied using a bunch merging RF scheme. Two RF cavities at different frequencies are used to capture newly injected bunches and then merge them into the stored bunches. It was shown that this scheme could satisfy the requirements on intensity and duty cycle set by the experiment. This merging scheme has now been revised with new simulation software providing new results for 6He and 18Ne. Furthermore bunch merging has been studied for the second CERN-based scenario using 8Li and 8B.

  12. Merging of gamma radiographic and ultrasonic inspection data: bibliographical survey

    International Nuclear Information System (INIS)

    Gautier, S.

    1995-01-01

    This paper presents a number of experimental data processing notions with the aim of developing an NDT method based on merging ultrasonic and gamma radiographic data. We first review the industrial context concerned and, before moving on to specific data merging problems, we discuss the difficulties of reconstruction using only one type of data (radiographic or ultrasonic). The main part of the report begins with a brief reminder of gamma radiation and ultrasonic wave propagation principles. Certain imaging and reconstruction methods conventionally used for each type of measurement are also presented. Reconstruction problems are then directly approached in algebraic form. For the type of problem studied, the inspection data alone cannot lead to satisfactory reconstructions and we evidence the need to regulate the problem by introducing deductive information on the object to be reconstructed. The Bayes' approach provides a self-consistent means of integrating both the data information and the deductive information. It is based on probabilistic models of the variables involved, notably those of the object sought. We discuss at some length certain models of images used in gamma radiography (independent variable fields, variables having a Markov-type structure) and the Bernoulli-Gauss-type models used for ultrasonic trace deconvolution. Finally, we outline data merging paths. A formal Bayes' framework is used to present two merging approaches, after which we briefly describe our projects for the processing of already available experimental data. (author)

  13. Catalysis by metallic nanoparticles in solution: Thermosensitive microgels as nanoreactors

    OpenAIRE

    Roa, Rafael; Angioletti-Uberti, Stefano; Lu, Yan; Dzubiella, Joachim; Piazza, Francesco; Ballauff, Matthias

    2018-01-01

    Metallic nanoparticles have been used as catalysts for various reactions, and the huge literature on the subject is hard to overlook. In many applications, the nanoparticles must be affixed to a colloidal carrier for easy handling during catalysis. These "passive carriers" (e.g., dendrimers) serve for a controlled synthesis of the nanoparticles and prevent coagulation during catalysis. Recently, hybrids from nanoparticles and polymers have been developed that allow us to change the catalytic ...

  14. 3. International conference on catalysis in membrane reactors

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-09-01

    The 3. International Conference on Catalysis in Membrane Reactors, Copenhagen, Denmark, is a continuation of the previous conferences held in Villeurbanne 1994 and Moscow 1996 and will deal with the rapid developments taking place within membranes with emphasis on membrane catalysis. The approx. 80 contributions in form of plenary lectures and posters discuss hydrogen production, methane reforming into syngas, selectivity and specificity of various membranes etc. The conference is organised by the Danish Catalytic Society under the Danish Society for Chemical Engineering. (EG)

  15. Dedicated Beamline Facilities for Catalytic Research. Synchrotron Catalysis Consortium (SCC)

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Jingguang [Columbia Univ., New York, NY; Frenkel, Anatoly [Yeshiva Univ., New York, NY (United States); Rodriguez, Jose [Brookhaven National Lab. (BNL), Upton, NY (United States); Adzic, Radoslav [Brookhaven National Lab. (BNL), Upton, NY (United States); Bare, Simon R. [UOP LLC, Des Plaines, IL (United States); Hulbert, Steve L. [Brookhaven National Lab. (BNL), Upton, NY (United States); Karim, Ayman [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Mullins, David R. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Overbury, Steve [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2015-03-04

    Synchrotron spectroscopies offer unique advantages over conventional techniques, including higher detection sensitivity and molecular specificity, faster detection rate, and more in-depth information regarding the structural, electronic and catalytic properties under in-situ reaction conditions. Despite these advantages, synchrotron techniques are often underutilized or unexplored by the catalysis community due to various perceived and real barriers, which will be addressed in the current proposal. Since its establishment in 2005, the Synchrotron Catalysis Consortium (SCC) has coordinated significant efforts to promote the utilization of cutting-edge catalytic research under in-situ conditions. The purpose of the current renewal proposal is aimed to provide assistance, and to develop new sciences/techniques, for the catalysis community through the following concerted efforts: Coordinating the implementation of a suite of beamlines for catalysis studies at the new NSLS-II synchrotron source; Providing assistance and coordination for catalysis users at an SSRL catalysis beamline during the initial period of NSLS to NSLS II transition; Designing in-situ reactors for a variety of catalytic and electrocatalytic studies; Assisting experimental set-up and data analysis by a dedicated research scientist; Offering training courses and help sessions by the PIs and co-PIs.

  16. Tandem rhodium catalysis: exploiting sulfoxides for asymmetric transition-metal catalysis.

    Science.gov (United States)

    Kou, K G M; Dong, V M

    2015-06-07

    Sulfoxides are uncommon substrates for transition-metal catalysis due to their propensity to inhibit catalyst turnover. In a collaborative effort with Ken Houk, we developed the first dynamic kinetic resolution (DKR) of allylic sulfoxides using asymmetric rhodium-catalyzed hydrogenation. A detailed mechanistic analysis of this transformation using both experimental and theoretical methods revealed rhodium to be a tandem catalyst that promoted both hydrogenation of the alkene and racemization of the allylic sulfoxide. Using a combination of deuterium labelling and DFT studies, a novel mode of allylic sulfoxide racemization via a Rh(III)-π-allyl intermediate was identified.

  17. Filtered Rayleigh scattering mixing measurements of merging and non-merging streamwise vortex interactions in supersonic flow

    Science.gov (United States)

    Ground, Cody R.; Gopal, Vijay; Maddalena, Luca

    2018-04-01

    By introducing large-scale streamwise vortices into a supersonic flow it is possible to enhance the rate of mixing between two fluid streams. However, increased vorticity content alone does not explicitly serve as a predictor of mixing enhancement. Additional factors, particularly the mutual interactions occurring between neighboring vortical structures, affect the underlying fundamental physics that influence the rate at which the fluids mix. As part of a larger systematic study on supersonic streamwise vortex interactions, this work experimentally quantifies the average rate of mixing of helium and air in the presence of two separate modes of vortex interaction, the merging and non-merging of a pair of co-rotating vortices. In these experiments vortex-generating expansion ramps are placed on a strut injector. The freestream Mach number is set at 2.5 and helium is injected as a passive scalar. Average injectant mole fractions at selected flow planes downstream of the injector are measured utilizing the filtered Rayleigh scattering technique. The filtered Rayleigh scattering measurements reveal that, in the domain surveyed, the merging vortex interaction strongly displaces the plume from its initial horizontal orientation while the non-merging vortex interaction more rapidly mixes the helium and air. The results of the current experiments are consistent with associated knowledge derived from previous analyses of the two studied configurations which have included the detailed experimental characterization of entrainment, turbulent kinetic energy, and vorticity of both modes of vortex interaction.

  18. The effect of vortex merging and non-merging on the transfer of modal turbulent kinetic energy content

    Science.gov (United States)

    Ground, Cody; Vergine, Fabrizio; Maddalena, Luca

    2016-08-01

    A defining feature of the turbulent free shear layer is that its growth is hindered by compressibility effects, thus limiting its potential to sufficiently mix the injected fuel and surrounding airstream at the supersonic Mach numbers intrinsic to the combustor of air-breathing hypersonic vehicles. The introduction of streamwise vorticity is often proposed in an attempt to counteract these undesired effects. This fact makes the strategy of introducing multiple streamwise vortices and imposing upon them certain modes of mutual interaction in order to potentially enhance mixing an intriguing concept. However, many underlying fundamental characteristics of the flowfields in the presence such interactions are not yet well understood; therefore, the fundamental physics of these flowfields should be independently investigated before the explicit mixing performance is characterized. In this work, experimental measurements are taken with the stereoscopic particle image velocimetry technique on two specifically targeted modes of vortex interaction—the merging and non-merging of two corotating vortices. The fluctuating velocity fields are analyzed utilizing the proper orthogonal decomposition (POD) in order to identify the content, organization, and distribution of the modal turbulent kinetic energy content of the fluctuating velocity eigenmodes. The effects of the two modes of vortex interaction are revealed by the POD analysis which shows distinct differences in the modal features of the two cases. When comparing the low-order eigenmodes of the two cases, the size of the structures contained within the first ten modes is seen to increase as the flow progresses downstream for the merging case, whereas the opposite is true for the non-merging case. Additionally, the relative modal energy contribution of the first ten eigenmodes increases as the vortices evolve downstream for the merging case, whereas in the non-merging case the relative modal energy contribution decreases

  19. Loop residues and catalysis in OMP synthase

    DEFF Research Database (Denmark)

    Wang, Gary P.; Hansen, Michael Riis; Grubmeyer, Charles

    2012-01-01

    binding of OMP or PRPP in binary complexes was affected little by loop mutation, suggesting that the energetics of ground-state binding have little contribution from the catalytic loop, or that a favorable binding energy is offset by costs of loop reorganization. Pre-steady-state kinetics for mutants...... values for all four substrate molecules. The 20% (i.e., 1.20) intrinsic [1?-3H]OMP kinetic isotope effect (KIE) for WT is masked because of high forward and reverse commitment factors. K103A failed to express intrinsic KIEs fully (1.095 ± 0.013). In contrast, H105A, which has a smaller catalytic lesion...... (preceding paper in this issue, DOI 10.1021/bi300083p)]. The full expression of KIEs by H105A and E107A may result from a less secure closure of the catalytic loop. The lower level of expression of the KIE by K103A suggests that in these mutant proteins the major barrier to catalysis is successful closure...

  20. Catalysis in high-temperature fuel cells.

    Science.gov (United States)

    Föger, K; Ahmed, K

    2005-02-17

    Catalysis plays a critical role in solid oxide fuel cell systems. The electrochemical reactions within the cell--oxygen dissociation on the cathode and electrochemical fuel combustion on the anode--are catalytic reactions. The fuels used in high-temperature fuel cells, for example, natural gas, propane, or liquid hydrocarbons, need to be preprocessed to a form suitable for conversion on the anode-sulfur removal and pre-reforming. The unconverted fuel (economic fuel utilization around 85%) is commonly combusted using a catalytic burner. Ceramic Fuel Cells Ltd. has developed anodes that in addition to having electrochemical activity also are reactive for internal steam reforming of methane. This can simplify fuel preprocessing, but its main advantage is thermal management of the fuel cell stack by endothermic heat removal. Using this approach, the objective of fuel preprocessing is to produce a methane-rich fuel stream but with all higher hydrocarbons removed. Sulfur removal can be achieved by absorption or hydro-desulfurization (HDS). Depending on the system configuration, hydrogen is also required for start-up and shutdown. Reactor operating parameters are strongly tied to fuel cell operational regimes, thus often limiting optimization of the catalytic reactors. In this paper we discuss operation of an authothermal reforming reactor for hydrogen generation for HDS and start-up/shutdown, and development of a pre-reformer for converting propane to a methane-rich fuel stream.

  1. Ferroelectric based catalysis: Switchable surface chemistry

    Science.gov (United States)

    Kakekhani, Arvin; Ismail-Beigi, Sohrab

    2015-03-01

    We describe a new class of catalysts that uses an epitaxial monolayer of a transition metal oxide on a ferroelectric substrate. The ferroelectric polarization switches the surface chemistry between strongly adsorptive and strongly desorptive regimes, circumventing difficulties encountered on non-switchable catalytic surfaces where the Sabatier principle dictates a moderate surface-molecule interaction strength. This method is general and can, in principle, be applied to many reactions, and for each case the choice of the transition oxide monolayer can be optimized. Here, as a specific example, we show how simultaneous NOx direct decomposition (into N2 and O2) and CO oxidation can be achieved efficiently on CrO2 terminated PbTiO3, while circumventing oxygen (and sulfur) poisoning issues. One should note that NOx direct decomposition has been an open challenge in automotive emission control industry. Our method can expand the range of catalytically active elements to those which are not conventionally considered for catalysis and which are more economical, e.g., Cr (for NOx direct decomposition and CO oxidation) instead of canonical precious metal catalysts. Primary support from Toyota Motor Engineering and Manufacturing, North America, Inc.

  2. Intermittent magnetic reconnection in TS-3 merging experiment

    International Nuclear Information System (INIS)

    Ono, Y.; Hayashi, Y.; Ii, T.; Tanabe, H.; Ito, S.; Kuwahata, A.; Ito, T.; Kamino, Y.; Yamada, T.; Inomoto, M.

    2011-01-01

    Ejection of current sheet with plasma mass causes impulsive and intermittent magnetic reconnection in the TS-3 spherical tokamak (ST) merging experiment. Under high guide toroidal field, the sheet resistivity is almost classical due to the sheet thickness much longer than the ion gyroradius. Large inflow flux and low current-sheet resistivity result in flux and plasma pileup followed by rapid growth of the current sheet. When the pileup exceeds a critical limit, the sheet is ejected mechanically from the squeezed X-point area. The reconnection (outflow) speed is slow during the flux/plasma pileup and is fast during the ejection, suggesting that intermittent reconnection similar to the solar flare increases the averaged reconnection speed. These transient effects enable the merging tokamaks to have the fast reconnection as well as the high-power reconnection heating, even when their current-sheet resistivity is low under high guide field.

  3. The half-wave rectifier response of the magnetosphere and antiparallel merging

    Science.gov (United States)

    Crooker, N. U.

    1980-01-01

    In some ways the magnetosphere behaves as if merging occurs only when the interplanetary magnetic field (IMF) is southward, and in other ways it behaves as if merging occurs for all IMF orientations. An explanation of this duality is offered in terms of a geometrical antiparallel merging model which predicts merging for all IMF orientations but magnetic flux transfer to the tail only for southward IMF. This is in contrast to previous models of component merging, where merging and flux transfer occur together for nearly all IMF orientations. That the problematic duality can be explained by the model is compelling evidence that antiparallel merging should be seriously considered in constructing theories of the merging process.

  4. High-Resolution Imaging of Colliding and Merging Galaxies

    Science.gov (United States)

    Whitmore, Brad

    1991-07-01

    We propose to obtain high-resolution images, using the WF/PC, of two colliding and merging galaxies (i.e., NGC 4038/4039 = "The Antennae" and NGC 7252 ="Atoms-for-Peace Galaxy". Our goal is to use HST to make critical observations of each object in order to gain a better understanding of the various phases of the merger process. Our primary objective is to determine whether globular clusters are formed during mergers\\?

  5. The Fourth Workshop on Lineshape Code Comparison: Line Merging

    Directory of Open Access Journals (Sweden)

    Spiros Alexiou

    2018-03-01

    Full Text Available For a given set of plasma parameters, along a single series (Lyman, Balmer, etc. the lines with higher principal quantum number (n lines get progressively wider, closer to each other, and start merging for a certain critical n. In the present work, four different codes (with further options are used to calculate the entire Balmer series for moderate and high electron densities. Particular attention is paid to the relevant physics, such as the cutoff criteria, strong and penetrating electron collisions.

  6. Center for Catalysis at Iowa State University

    Energy Technology Data Exchange (ETDEWEB)

    Kraus, George A.

    2006-10-17

    The overall objective of this proposal is to enable Iowa State University to establish a Center that enjoys world-class stature and eventually enhances the economy through the transfer of innovation from the laboratory to the marketplace. The funds have been used to support experimental proposals from interdisciplinary research teams in areas related to catalysis and green chemistry. Specific focus areas included: • Catalytic conversion of renewable natural resources to industrial materials • Development of new catalysts for the oxidation or reduction of commodity chemicals • Use of enzymes and microorganisms in biocatalysis • Development of new, environmentally friendly reactions of industrial importance These focus areas intersect with barriers from the MYTP draft document. Specifically, section 2.4.3.1 Processing and Conversion has a list of bulleted items under Improved Chemical Conversions that includes new hydrogenation catalysts, milder oxidation catalysts, new catalysts for dehydration and selective bond cleavage catalysts. Specifically, the four sections are: 1. Catalyst development (7.4.12.A) 2. Conversion of glycerol (7.4.12.B) 3. Conversion of biodiesel (7.4.12.C) 4. Glucose from starch (7.4.12.D) All funded projects are part of a soybean or corn biorefinery. Two funded projects that have made significant progress toward goals of the MYTP draft document are: Catalysts to convert feedstocks with high fatty acid content to biodiesel (Kraus, Lin, Verkade) and Conversion of Glycerol into 1,3-Propanediol (Lin, Kraus). Currently, biodiesel is prepared using homogeneous base catalysis. However, as producers look for feedstocks other than soybean oil, such as waste restaurant oils and rendered animal fats, they have observed a large amount of free fatty acids contained in the feedstocks. Free fatty acids cannot be converted into biodiesel using homogeneous base-mediated processes. The CCAT catalyst system offers an integrated and cooperative catalytic

  7. Catalysis-by-design impacts assessment

    Energy Technology Data Exchange (ETDEWEB)

    Fassbender, L L; Young, J K [Pacific Northwest Lab., Richland, WA (USA); Sen, R K [Sen (R.K.) and Associates, Washington, DC (USA)

    1991-05-01

    Catalyst researchers have always recognized the need to develop a detailed understanding of the mechanisms of catalytic processes, and have hoped that it would lead to developing a theoretical predictive base to guide the search for new catalysts. This understanding allows one to develop a set of hierarchical models, from fundamental atomic-level ab-initio models to detailed engineering simulations of reactor systems, to direct the search for optimized, efficient catalyst systems. During the last two decades, the explosions of advanced surface analysis techniques have helped considerably to develop the building blocks for understanding various catalytic reactions. An effort to couple these theoretical and experimental advances to develop a set of hierarchical models to predict the nature of catalytic materials is a program entitled Catalysis-by-Design (CRD).'' In assessing the potential impacts of CBD on US industry, the key point to remember is that the value of the program lies in developing a novel methodology to search for new catalyst systems. Industrial researchers can then use this methodology to develop proprietary catalysts. Most companies involved in catalyst R D have two types of ongoing projects. The first type, what we call market-driven R D,'' are projects that support and improve upon a company's existing product lines. Project of the second type, technology-driven R D,'' are longer term, involve the development of totally new catalysts, and are initiated through scientists' research ideas. The CBD approach will impact both types of projects. However, this analysis indicates that the near-term impacts will be on market-driven'' projects. The conclusions and recommendations presented in this report were obtained by the authors through personal interviews with individuals involved in a variety of industrial catalyst development programs and through the three CBD workshops held in the summer of 1989. 34 refs., 7 figs., 7 tabs.

  8. Studies on Plasmoid Merging using Compact Toroid Injectors

    Science.gov (United States)

    Allfrey, Ian; Matsumoto, Tadafumi; Roche, Thomas; Gota, Hiroshi; Edo, Takahiro; Asai, Tomohiko; Sheftman, Daniel; Osin Team; Dima Team

    2017-10-01

    C-2 and C-2U experiments have used magnetized coaxial plasma guns (MCPG) to inject compact toroids (CTs) for refueling the long-lived advanced beam-driven field-reversed configuration (FRC) plasma. This refueling method will also be used for the C-2W experiment. To minimize momentum transfer from the CT to the FRC two CTs are injected radially, diametrically opposed and coincident in time. To improve understanding of the CT characteristics TAE has a dedicated test bed for the development of CT injectors (CTI), where plasmoid merging experiments are performed. The test bed has two CTIs on axis with both axial and transverse magnetic fields. The 1 kG magnetic fields, intended to approximate the magnetic field strength and injection angle on C-2W, allow studies of cross-field transport and merging. Both CTIs are capable of injecting multiple CTs at up to 1 kHz. The resulting merged CT lives >100 μs with a radius of 25 cm. More detailed results of CT parameters will be presented.

  9. Droplets formation and merging in two-phase flow microfluidics.

    Science.gov (United States)

    Gu, Hao; Duits, Michel H G; Mugele, Frieder

    2011-01-01

    Two-phase flow microfluidics is emerging as a popular technology for a wide range of applications involving high throughput such as encapsulation, chemical synthesis and biochemical assays. Within this platform, the formation and merging of droplets inside an immiscible carrier fluid are two key procedures: (i) the emulsification step should lead to a very well controlled drop size (distribution); and (ii) the use of droplet as micro-reactors requires a reliable merging. A novel trend within this field is the use of additional active means of control besides the commonly used hydrodynamic manipulation. Electric fields are especially suitable for this, due to quantitative control over the amplitude and time dependence of the signals, and the flexibility in designing micro-electrode geometries. With this, the formation and merging of droplets can be achieved on-demand and with high precision. In this review on two-phase flow microfluidics, particular emphasis is given on these aspects. Also recent innovations in microfabrication technologies used for this purpose will be discussed.

  10. Droplets Formation and Merging in Two-Phase Flow Microfluidics

    Directory of Open Access Journals (Sweden)

    Hao Gu

    2011-04-01

    Full Text Available Two-phase flow microfluidics is emerging as a popular technology for a wide range of applications involving high throughput such as encapsulation, chemical synthesis and biochemical assays. Within this platform, the formation and merging of droplets inside an immiscible carrier fluid are two key procedures: (i the emulsification step should lead to a very well controlled drop size (distribution; and (ii the use of droplet as micro-reactors requires a reliable merging. A novel trend within this field is the use of additional active means of control besides the commonly used hydrodynamic manipulation. Electric fields are especially suitable for this, due to quantitative control over the amplitude and time dependence of the signals, and the flexibility in designing micro-electrode geometries. With this, the formation and merging of droplets can be achieved on-demand and with high precision. In this review on two-phase flow microfluidics, particular emphasis is given on these aspects. Also recent innovations in microfabrication technologies used for this purpose will be discussed.

  11. Toolsets for Airborne Data (TAD): Customized Data Merging Function

    Science.gov (United States)

    Benson, A.; Peeters, M. C.; Perez, J.; Parker, L.; Chen, G.

    2013-12-01

    NASA has conducted airborne tropospheric chemistry studies for about three decades. These field campaigns have generated a great wealth of observations, including a wide range of the trace gases and aerosol properties. The ASDC Toolset for Airborne Data (TAD) is being designed to meet the user community needs for manipulating aircraft data for scientific research on climate change and air quality relevant issues. Prior to the actual toolset development, a comprehensive metadata database was created to compensate for the absence of standardization of the ICARTT data format in which the data is stored. This database tracks the Principal Investigator-provided metadata, and links the measurement variables to a common naming system that was developed as a part of this project. This database is used by the data merging module. Most aircraft data reported during a single flight is not on a consistent time base and is difficult to intercompare. This module provides the user with the ability to merge original data measurements from multiple data providers into a specified time interval or common time base. The database development, common naming scheme and data merge module development will be presented.

  12. Biodiesel forming reactions using heterogeneous catalysis

    Science.gov (United States)

    Liu, Yijun

    Biodiesel synthesis from biomass provides a means for utilizing effectively renewable resources, a way to convert waste vegetable oils and animal fats to a useful product, a way to recycle carbon dioxide for a combustion fuel, and production of a fuel that is biodegradable, non-toxic, and has a lower emission profile than petroleum-diesel. Free fatty acid (FFA) esterification and triglyceride (TG) transesterification with low molecular weight alcohols constitute the synthetic routes to prepare biodiesel from lipid feedstocks. This project was aimed at developing a better understanding of important fundamental issues involved in heterogeneous catalyzed biodiesel forming reactions using mainly model compounds, representing part of on-going efforts to build up a rational base for assay, design, and performance optimization of solid acids/bases in biodiesel synthesis. As FFA esterification proceeds, water is continuously formed as a byproduct and affects reaction rates in a negative manner. Using sulfuric acid (as a catalyst) and acetic acid (as a model compound for FFA), the impact of increasing concentrations of water on acid catalysis was investigated. The order of the water effect on reaction rate was determined to be -0.83. Sulfuric acid lost up to 90% activity as the amount of water present increased. The nature of the negative effect of water on esterification was found to go beyond the scope of reverse hydrolysis and was associated with the diminished acid strength of sulfuric acid as a result of the preferential solvation by water molecules of its catalytic protons. The results indicate that as esterification progresses and byproduct water is produced, deactivation of a Bronsted acid catalyst like H2SO4 occurs. Using a solid composite acid (SAC-13) as an example of heterogeneous catalysts and sulfuric acid as a homogeneous reference, similar reaction inhibition by water was demonstrated for homogeneous and heterogeneous catalysis. This similarity together with

  13. Kinetic evolutionary behavior of catalysis-select migration

    International Nuclear Information System (INIS)

    Wu Yuan-Gang; Lin Zhen-Quan; Ke Jian-Hong

    2012-01-01

    We propose a catalysis-select migration driven evolution model of two-species (A- and B-species) aggregates, where one unit of species A migrates to species B under the catalysts of species C, while under the catalysts of species D the reaction will become one unit of species B migrating to species A. Meanwhile the catalyst aggregates of species C perform self-coagulation, as do the species D aggregates. We study this catalysis-select migration driven kinetic aggregation phenomena using the generalized Smoluchowski rate equation approach with C species catalysis-select migration rate kernel K(k;i,j) = Kkij and D species catalysis-select migration rate kernel J(k;i,j)= Jkij. The kinetic evolution behaviour is found to be dominated by the competition between the catalysis-select immigration and emigration, in which the competition is between JD 0 and KC 0 (D 0 and C 0 are the initial numbers of the monomers of species D and C, respectively). When JD 0 −KC 0 > 0, the aggregate size distribution of species A satisfies the conventional scaling form and that of species B satisfies a modified scaling form. And in the case of JD 0 −KC 0 0 −KC 0 > 0 case. (interdisciplinary physics and related areas of science and technology)

  14. Francois Garin: Pioneer work in catalysis through synchrotron radiation

    International Nuclear Information System (INIS)

    Bazin, Dominique

    2014-01-01

    Starting from the late seventies, the progressively increased availability of beamlines dedicated to X-ray absorption spectroscopy allowed the execution of experiments in chemistry. In this manuscript, I describe the contribution of Francois Garin at the frontier of heterogeneous catalysis and synchrotron radiation. Working at LURE as a scientific in charge of a beamline dedicated to X-ray absorption spectroscopy during almost twenty years and thus, having the opportunity to discuss with research groups working in heterogeneous catalysis in Europe as well as in the United States, it was quite easy to show that his work is clearly at the origin of current research in heterogeneous catalysis, not only in France, but in different synchrotron radiation centres. (authors)

  15. 2008 Gordon Research Conference on Catalysis [Conference summary report

    Energy Technology Data Exchange (ETDEWEB)

    Soled, Stuart L.; Gray, Nancy Ryan

    2009-01-01

    The GRC on Catalysis is one of the most prestigious catalysis conferences as it brings together leading researchers from around the world to discuss their latest, most exciting work in catalysis. The 2008 conference will continue this tradition. The conference will cover a variety of themes including new catalytic materials, theoretical and experimental approaches to improve understanding of kinetics and transport phenomena, and state of the art nanoscale characterization probes to monitor active sites. The conference promotes interactions among established researchers and young scientists. It provides a venue for students to meet, talk to and learn from some of the world leading researchers in the area. It also gives them a platform for displaying their own work during the poster sessions. The informal nature of the meeting, excellent quality of the presentations and posters, and ability to meet many outstanding colleagues makes this an excellent conference.

  16. Isoporphyrin Intermediate in Heme Oxygenase Catalysis

    Science.gov (United States)

    Evans, John P.; Niemevz, Fernando; Buldain, Graciela; de Montellano, Paul Ortiz

    2008-01-01

    Human heme oxygenase-1 (hHO-1) catalyzes the O2- and NADPH-dependent oxidation of heme to biliverdin, CO, and free iron. The first step involves regiospecific insertion of an oxygen atom at the α-meso carbon by a ferric hydroperoxide and is predicted to proceed via an isoporphyrin π-cation intermediate. Here we report spectroscopic detection of a transient intermediate during oxidation by hHO-1 of α-meso-phenylheme-IX, α-meso-(p-methylphenyl)-mesoheme-III, and α-meso-(p-trifluoromethylphenyl)-mesoheme-III. In agreement with previous experiments (Wang, J., Niemevz, F., Lad, L., Huang, L., Alvarez, D. E., Buldain, G., Poulos, T. L., and Ortiz de Montellano, P. R. (2004) J. Biol. Chem. 279, 42593–42604), only the α-biliverdin isomer is produced with concomitant formation of the corresponding benzoic acid. The transient intermediate observed in the NADPH-P450 reductase-catalyzed reaction accumulated when the reaction was supported by H2O2 and exhibited the absorption maxima at 435 and 930 nm characteristic of an isoporphyrin. Product analysis by reversed phase high performance liquid chromatography and liquid chromatography electrospray ionization mass spectrometry of the product generated with H2O2 identified it as an isoporphyrin that, on quenching, decayed to benzoylbiliverdin. In the presence of H218O2, one labeled oxygen atom was incorporated into these products. The hHO-1-isoporphyrin complexes were found to have half-lives of 1.7 and 2.4 h for the p-trifluoromethyl- and p-methyl-substituted phenylhemes, respectively. The addition of NADPH-P450 reductase to the H2O2-generated hHO-1-isoporphyrin complex produced α-biliverdin, confirming its role as a reaction intermediate. Identification of an isoporphyrin intermediate in the catalytic sequence of hHO-1, the first such intermediate observed in hemoprotein catalysis, completes our understanding of the critical first step of heme oxidation. PMID:18487208

  17. New and future developments in catalysis activation of carbon dioxide

    CERN Document Server

    Suib, Steven L

    2013-01-01

    New and Future Developments in Catalysis is a package of books that compile the latest ideas concerning alternate and renewable energy sources and the role that catalysis plays in converting new renewable feedstock into biofuels and biochemicals. Both homogeneous and heterogeneous catalysts and catalytic processes will be discussed in a unified and comprehensive approach. There will be extensive cross-referencing within all volumes. This volume presents a complete picture of all carbon dioxide (CO2) sources, outlines the environmental concerns regarding CO2, and critica

  18. KCC1: First Nanoparticle developed by KAUST Catalysis Center

    KAUST Repository

    Basset, Jean-Marie

    2010-08-01

    KCC1 is the first Nanoparticle developed by KAUST Catalysis Center. Director of KAUST Catalysis Center, Dr. Jean-Marie Basset, Senior Research Scientist at KCC, Dr. Vivek Polshettiwar, and Dr. Dongkyu Cha of the Advanced Nanofabrication Imaging & Characterization Core Laboratory discuss the details of this recent discovery. This video was produced by KAUST Visualization Laboratory and KAUST Technology Transfer and Innovation - Terence McElwee, Director, Technology Transfer and Innovation - IP@kaust.edu.sa This technology is part of KAUST\\'s technology commercialization program that seeks to stimulate development and commercial use of KAUST-developed technologies. For more information email us at ip@kaust.edu.sa.

  19. Seventh BES [Basic Energy Sciences] catalysis and surface chemistry research conference

    International Nuclear Information System (INIS)

    1990-03-01

    Research programs on catalysis and surface chemistry are presented. A total of fifty-seven topics are included. Areas of research include heterogeneous catalysis; catalysis in hydrogenation, desulfurization, gasification, and redox reactions; studies of surface properties and surface active sites; catalyst supports; chemical activation, deactivation; selectivity, chemical preparation; molecular structure studies; sorption and dissociation. Individual projects are processed separately for the data bases

  20. Seventh BES (Basic Energy Sciences) catalysis and surface chemistry research conference

    Energy Technology Data Exchange (ETDEWEB)

    1990-03-01

    Research programs on catalysis and surface chemistry are presented. A total of fifty-seven topics are included. Areas of research include heterogeneous catalysis; catalysis in hydrogenation, desulfurization, gasification, and redox reactions; studies of surface properties and surface active sites; catalyst supports; chemical activation, deactivation; selectivity, chemical preparation; molecular structure studies; sorption and dissociation. Individual projects are processed separately for the data bases. (CBS)

  1. Magnetic conveyor belt for transporting and merging trapped atom clouds.

    Science.gov (United States)

    Hänsel, W; Reichel, J; Hommelhoff, P; Hänsch, T W

    2001-01-22

    We demonstrate an integrated magnetic device which transports cold atoms near a surface with very high positioning accuracy. Time-dependent currents in a lithographic conductor pattern create a moving chain of potential wells; atoms are transported in these wells while remaining confined in all three dimensions. We achieve mean fluxes up to 10(6) s(-1) with a negligible heating rate. An extension of this device allows merging of atom clouds by unification of two Ioffe-Pritchard potentials. The unification, which we demonstrate experimentally, can be performed without loss of phase space density. This novel, all-magnetic atom manipulation offers exciting perspectives, such as trapped-atom interferometry.

  2. Merging Satellite Precipitation Products for Improved Streamflow Simulations

    Science.gov (United States)

    Maggioni, V.; Massari, C.; Barbetta, S.; Camici, S.; Brocca, L.

    2017-12-01

    Accurate quantitative precipitation estimation is of great importance for water resources management, agricultural planning and forecasting and monitoring of natural hazards such as flash floods and landslides. In situ observations are limited around the Earth, especially in remote areas (e.g., complex terrain, dense vegetation), but currently available satellite precipitation products are able to provide global precipitation estimates with an accuracy that depends upon many factors (e.g., type of storms, temporal sampling, season, etc.). The recent SM2RAIN approach proposes to estimate rainfall by using satellite soil moisture observations. As opposed to traditional satellite precipitation methods, which sense cloud properties to retrieve instantaneous estimates, this new bottom-up approach makes use of two consecutive soil moisture measurements for obtaining an estimate of the fallen precipitation within the interval between two satellite overpasses. As a result, the nature of the measurement is different and complementary to the one of classical precipitation products and could provide a different valid perspective to substitute or improve current rainfall estimates. Therefore, we propose to merge SM2RAIN and the widely used TMPA 3B42RT product across Italy for a 6-year period (2010-2015) at daily/0.25deg temporal/spatial scale. Two conceptually different merging techniques are compared to each other and evaluated in terms of different statistical metrics, including hit bias, threat score, false alarm rates, and missed rainfall volumes. The first is based on the maximization of the temporal correlation with a reference dataset, while the second is based on a Bayesian approach, which provides a probabilistic satellite precipitation estimate derived from the joint probability distribution of observations and satellite estimates. The merged precipitation products show a better performance with respect to the parental satellite-based products in terms of categorical

  3. Electron-ion recombination rates for merged-beams experiments

    International Nuclear Information System (INIS)

    Pajek, M.

    1994-01-01

    Energy dependence of the electron-ion recombination rates are studied for different recombination processes (radiative recombination, three-body recombination, dissociative recombination) for Maxwellian relative velocity distribution of arbitrary asymmetry. The results are discussed in context of the electron-ion merged beams experiments in cooling ion storage rings. The question of indication of a possible contribution of the three-body recombination to the measured recombination rates versus relative energy is particularly addressed. Its influence on the electron beam temperature derived from the energy dependence of recombination rate is discussed

  4. Merged Search Algorithms for Radio Frequency Identification Anticollision

    Directory of Open Access Journals (Sweden)

    Bih-Yaw Shih

    2012-01-01

    The arbitration algorithm for RFID system is used to arbitrate all the tags to avoid the collision problem with the existence of multiple tags in the interrogation field of a transponder. A splitting algorithm which is called Binary Search Tree (BST is well known for multitags arbitration. In the current study, a splitting-based schema called Merged Search Tree is proposed to capture identification codes correctly for anticollision. Performance of the proposed algorithm is compared with the original BST according to time and power consumed during the arbitration process. The results show that the proposed model can reduce searching time and power consumed to achieve a better performance arbitration.

  5. Merged Real Time GNSS Solutions for the READI System

    Science.gov (United States)

    Santillan, V. M.; Geng, J.

    2014-12-01

    Real-time measurements from increasingly dense Global Navigational Satellite Systems (GNSS) networks located throughout the western US offer a substantial, albeit largely untapped, contribution towards the mitigation of seismic and other natural hazards. Analyzed continuously in real-time, currently over 600 instruments blanket the San Andreas and Cascadia fault systems of the North American plate boundary and can provide on-the-fly characterization of transient ground displacements highly complementary to traditional seismic strong-motion monitoring. However, the utility of GNSS systems depends on their resolution, and merged solutions of two or more independent estimation strategies have been shown to offer lower scatter and higher resolution. Towards this end, independent real time GNSS solutions produced by Scripps Inst. of Oceanography and Central Washington University (PANGA) are now being formally combined in pursuit of NASA's Real-Time Earthquake Analysis for Disaster Mitigation (READI) positioning goals. CWU produces precise point positioning (PPP) solutions while SIO produces ambiguity resolved PPP solutions (PPP-AR). The PPP-AR solutions have a ~5 mm RMS scatter in the horizontal and ~10mm in the vertical, however PPP-AR solutions can take tens of minutes to re-converge in case of data gaps. The PPP solutions produced by CWU use pre-cleaned data in which biases are estimated as non-integer ambiguities prior to formal positioning with GIPSY 6.2 using a real time stream editor developed at CWU. These solutions show ~20mm RMS scatter in the horizontal and ~50mm RMS scatter in the vertical but re-converge within 2 min. or less following cycle-slips or data outages. We have implemented the formal combination of the CWU and SCRIPPS ENU displacements using the independent solutions as input measurements to a simple 3-element state Kalman filter plus white noise. We are now merging solutions from 90 stations, including 30 in Cascadia, 39 in the Bay Area, and 21

  6. Understanding the fate of merging supermassive black holes

    International Nuclear Information System (INIS)

    Campanelli, Manuela

    2005-01-01

    Understanding the fate of merging supermassive black holes in galactic mergers, and the gravitational wave emission from this process, are important LISA science goals. To this end, we present results from numerical relativity simulations of binary black hole mergers using the so-called Lazarus approach to model gravitational radiation from these events. In particular, we focus here on some recent calculations of the final spin and recoil velocity of the remnant hole formed at the end of a binary black hole merger process, which may constrain the growth history of massive black holes at the core of galaxies and globular clusters

  7. Flow Merging and Hub Route Optimization in Collaborative Transportation

    Directory of Open Access Journals (Sweden)

    Kerui Weng

    2014-01-01

    Full Text Available This paper studies the optimal hub routing problem of merged tasks in collaborative transportation. This problem allows all carriers’ transportation tasks to reach the destinations optionally passing through 0, 1, or 2 hubs within limited distance, while a cost discount on arcs in the hub route could be acquired after paying fixed charges. The problem arises in the application of logistics, postal services, airline transportation, and so forth. We formulate the problem as a mixed-integer programming model, and provide two heuristic approaches, respectively, based on Lagrangian relaxation and Benders decomposition. Computational experiments show that the algorithms work well.

  8. Merging paradigms: Decision Making, Management, and Cognitive Control

    DEFF Research Database (Denmark)

    Rasmussen, Jens

    1996-01-01

    The paper discusses the trend in paradigms within decision research, drifting from concepts of decision making in terms of normative models of 'rational decision making, through behavioral models in terms of 'biases' - deviations from rational models, toward models of actual decision making...... behavior, such as the SRK concept, naturalistic decision making, and dynamic decision making.In this evolution, concepts such as decision making, management, and behavioral control merge and a concurrent change in concepts underlying design of systems aiming at control of behavior is visible, from...

  9. DNA-based asymmetric organometallic catalysis in water

    NARCIS (Netherlands)

    Oelerich, Jens; Roelfes, Gerard

    2013-01-01

    Here, the first examples of DNA-based organometallic catalysis in water that give rise to high enantioselectivities are described. Copper complexes of strongly intercalating ligands were found to enable the asymmetric intramolecular cyclopropanation of alpha-diazo-beta-keto sulfones in water. Up to

  10. Density functional theory in surface science and heterogeneous catalysis

    DEFF Research Database (Denmark)

    Nørskov, Jens Kehlet; Scheffler, M.; Toulhoat, H.

    2006-01-01

    Solid surfaces are used extensively as catalysts throughout the chemical industry, in the energy sector, and in environmental protection. Recently, density functional theory has started providing new insight into the atomic-scale mechanisms of heterogeneous catalysis, helping to interpret the large...

  11. International symposium on 'applications of zeolites in heterogeneous catalysis'

    Energy Technology Data Exchange (ETDEWEB)

    1978-11-01

    The International Symposium on applications of zeolites in heterogeneous catalysis, organized by the Hungarian Chemical Society (Szeged, Hung. 9/11-14/78), included 48 papers, which were published in the Vertical Bar3Vertical BarActa Phys. Chem. (Szeged) 24.

  12. Molecular catalysis and high-volume organic synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Khidekel, M L; Vasserberg, V E

    1977-01-01

    The field of catalysis is very wide. The properties of catalysts are briefly reviewed and compared with the properties of enzymes. Various uses of enxymes in industry (sugar from corn, cellulose breakdown, etc.) are pointed out. The types of homogeneous and heterogeneous catalysts for use in organic synthesis are discussed. 48 refs. (SJR)

  13. Pincer-porphyrin hybrids : Synthesis, self-assembly, and catalysis

    NARCIS (Netherlands)

    Suijkerbuijk, B.M.J.M.

    2007-01-01

    Metal complexes play an important role in established research areas such as catalysis and materials chemistry as well as in emerging fields of chemical exploration such as bioinorganic chemistry. Changes in the metal center's ligand environment, i.e., the nature and number of the Lewis basic atoms

  14. Sustainable Catalysis_Energy efficient reactions and Applications

    Science.gov (United States)

    This book chapter discusses various catalysts for environmental remediation. Detailed information on catalysis using ferrate and ferrite oxidation, TiO2 photocatalysis, and new catalysts (i.e., graphene, perovskites and graphitic carbon nitride) is provided for the degradation of...

  15. Examining the role of glutamic acid 183 in chloroperoxidase catalysis

    NARCIS (Netherlands)

    Yi, X.; Conesa, A.; Punt, P.J.; Hager, L.P.

    2003-01-01

    Site-directed mutagenesis has been used to investigate the role of glutamic acid 183 in chloroperoxidase catalysis. Based on the x-ray crystallographic structure of chloroperoxidase, Glu-183 is postulated to function on distal side of the heme prosthetic group as an acid-base catalyst in

  16. Alkylation of hydrothiophosphoryl compounds in conditions of interphase catalysis

    International Nuclear Information System (INIS)

    Aladzheva, I.M.; Odinets, I.L.; Petrovskij, P.V.; Mastryukova, T.A.; Kabachkin, M.I.

    1993-01-01

    A method of interphase catalysis permitted to develop a common method for synthesis of compounds with thiophosphoryl group. The effect of nature of hydrothiophosphoryl compound, alkylating agent, two-phase system and reaction conditions on alkylation product yields was investigated in detail

  17. Towards a generic model of catalysis | Grayson | Bulletin of the ...

    African Journals Online (AJOL)

    We consider polarizabilities and hardness/softness parameters to see how local polarizations of the electron density may also be responsible for activation of a localised area of a large molecule. KEY WORDS: Electrostatic catalysis, Geometrical strain, Environment strain, Entasis, Polarizability, Hardness and softness. Bull.

  18. bond activation and catalysis by Ru -pac complexes

    Indian Academy of Sciences (India)

    and their reactivity towards oxidation of a few organic compounds. Keywords. Kinetics; catalysis; -O–O- bond activation; Ru-pac complex; oxidation. 1. Introduction. Ru-pac complexes exhibit catalytic properties,1 in homogeneous conditions in the presence of oxygen atom donors, that mimic the biological enzymatic oxi-.

  19. Nitrogen doped carbon nanotubes : synthesis, characterization and catalysis

    NARCIS (Netherlands)

    van Dommele, S.

    2008-01-01

    Nitrogen containing Carbon Nanotubes (NCNT) have altered physical- and chemical properties with respect to polarity, conductivity and reactivity as compared to conventional carbon nanotubes (CNT) and have potential for use in electronic applications or catalysis. In this thesis the incorporation of

  20. Role of catalysis in sustainable production of synthetic elastomers

    Indian Academy of Sciences (India)

    productions, the impact of synthetic elastomer business cannot be overlooked. The need of ... Keywords. Elastomers; catalysis; tyres and automobiles; mechanism; manufacturing process. 1. ..... level fractional factorial design model was also developed to ..... Polybutadiene can be manufactured by a number of pro- cesses ...

  1. Two-dimensional zeolites in catalysis: current status and perspectives

    Czech Academy of Sciences Publication Activity Database

    Opanasenko, Maksym; Roth, Wieslaw Jerzy; Čejka, Jiří

    2016-01-01

    Roč. 6, č. 8 (2016), s. 2467-2484 ISSN 2044-4753 R&D Projects: GA ČR GP13-17593P; GA ČR(CZ) GAP106/12/0189 Institutional support: RVO:61388955 Keywords : mesoporous molecular sieves * catalysis * acylation reactions Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 5.773, year: 2016

  2. Simulating merging binary black holes with nearly extremal spins

    International Nuclear Information System (INIS)

    Lovelace, Geoffrey; Scheel, Mark A.; Szilagyi, Bela

    2011-01-01

    Astrophysically realistic black holes may have spins that are nearly extremal (i.e., close to 1 in dimensionless units). Numerical simulations of binary black holes are important tools both for calibrating analytical templates for gravitational-wave detection and for exploring the nonlinear dynamics of curved spacetime. However, all previous simulations of binary-black-hole inspiral, merger, and ringdown have been limited by an apparently insurmountable barrier: the merging holes' spins could not exceed 0.93, which is still a long way from the maximum possible value in terms of the physical effects of the spin. In this paper, we surpass this limit for the first time, opening the way to explore numerically the behavior of merging, nearly extremal black holes. Specifically, using an improved initial-data method suitable for binary black holes with nearly extremal spins, we simulate the inspiral (through 12.5 orbits), merger and ringdown of two equal-mass black holes with equal spins of magnitude 0.95 antialigned with the orbital angular momentum.

  3. HR competencies at a merged Higher Education Institution

    Directory of Open Access Journals (Sweden)

    Cecile M. Schultz

    2010-06-01

    Research purposes: The aim of this study was to determine the HR competencies at a merged higher education institution. Other objectives were to establish the satisfaction of academics, administrative staff and management regarding the HR competencies and the importance thereof. Motivation for the study: Human resource professionals require assistance by providing HR competencies necessary to add value at a merged higher education institution. Research designs, approaches and methods: A quantitative research design was employed as the research strategy. The questionnaire was based on the literature, the business plan and the HR balanced scorecard report. The target population was 1363 permanent staff on one campus and the response rate was 28%. A principal factor analysis, spider charts and box plots were utilised for data analysis. The results indicated business knowledge, HR practices, personal skills and management skills as the vital HR competencies. Practical implications: Staff were not satisfied with the current HR competencies and consequently this necessitated attention to improve the deficient areas. Contribution: This study shows that limited research was done with regard to HR competencies in the South African higher education backdrop.

  4. Merging of independent condensates: disentangling the Kibble-Zurek mechanism

    Science.gov (United States)

    Ville, Jean-Loup; Aidelsburger, Monika; Saint-Jalm, Raphael; Nascimbene, Sylvain; Beugnon, Jerome; Dalibard, Jean

    2017-04-01

    An important step in the study of out-of-equilibrium physics is the Kibble-Zurek theory which describes a system after a quench through a second-order phase transition. This was studied in our group with a temperature quench across the normal-to-superfluid phase transition in an annular trap geometry, inducing the formation of supercurrents. Their magnitude and direction were detected by measuring spiral patterns resulting from the interference of the ring-shaped condensate with a central reference disk. According to the KZ mechanism domains of phase are created during the quench, with a characteristic size depending of its duration. In our case this results in a stochastic formation of supercurrents depending on the relative phases of the domains. As a next step of this study, we now design ourselves the patches thanks to our tunable trapping potential. We control both the number of condensates to be merged (from one to twelve) and their merging time. We report an increase of the vorticity in the ring for an increased number of patches compatible with a random phase model. We further investigate the time required by the phase to homogenize between two condensates.

  5. Patterns of magnetic field merging sites on the magnetopause

    International Nuclear Information System (INIS)

    Luhmann, J.G.; Walker, R.J.; Russell, C.T.; Crooker, N.U.; Spreiter, J.R.; Stahara, S.S.

    1984-01-01

    Several years ago, Crooker presented a qualitative picture of the merging sites on the magnetopause defined as the points where the magnetospheric and magnetosheath field are antiparallel. However, Cowley pointed out that merging can also occur where these fields are not exactly antiparallel, but merely have antiparallel components. Using realistic models of the magnetosphere and magnetosheath magnetic fields, the angles between the fields at the magnetopause boundary were determined for different interplanetary field orientations, including radial field and Parker spiral field. The results are summarized in Figure 1, which displays contours on the dayside magnetopause (viewed from the sun, i.e., the GSE Y-Z plane projection) of equal value of the cosine of the angle between the magnetospheric and magnetosheath model fields. Only contours with negative values, implying some antiparallel component, are shown. Values at the contours, starting with the contour filled with shading, are -.98, -.95, -.9, -.8, -.7, -.6, -.5, -.4, -.3, -.2, -.1, -.0. The interplanetary field orientations are indicated in vector notation in the lower right corners. In particular, the pattern for a 45 0 cone angle is shown in the fourth diagram in the right hand column and patterns for northward and southward fields occupy the first position in the first column and the second position in the right hand column. These results can be used for comparisons with observed distribution of flux transfer events and for studies of magnetospheric particle leakage

  6. Evolution and merging of binaries with compact objects

    International Nuclear Information System (INIS)

    Bethe, Hans A.; Brown, Gerald E.; Lee, Chang-Hwan

    2007-01-01

    In the light of recent observations in which short γ-ray bursts are interpreted as arising from black-hole(BH), neutron-star(NS) or NS-NS mergings we would like to review our research on the evolution of compact binaries, especially those containing NS's. These were carried out with predictions for LIGO in mind, but are directly applicable to short γ-ray bursts in the interpretation above. Most important in our review is that we show that the standard scenario for evolving NS-NS binaries always ends up with a low-mass BH (LMBH), NS binary. Bethe and Brown [1998, Astrophys. J. 506, 780] showed that this fate could be avoided if the two giants in the progenitor binary burned He at the same time, and that in this way the binary could avoid the common envelope evolution of the NS with red giant companion which sends the first born NS into a BH in the standard scenario. The burning of He at the same time requires, for the more massive giants such as the progenitors of the Hulse-Taylor binary NS that the two giants be within 4% of each other in zero age main sequence (ZAMS) mass. Applying this criterion to all binaries results in a factor ∼5 of LMBH-NS binaries as compared with NS-NS binaries. Although this factor is substantially less than the originally claimed factor of 20 which Bethe and Brown (1998) estimated, largely because a careful evolution has been carried through here, our factor 5 is augmented by a factor of ∼8 arising from the higher rate of star formation in the earlier Galaxy from which the BH-NS binaries came from. Furthermore, here we calculate the mergers for short-hard gamma-ray bursts, whereas Bethe and Brown's factor 20 included a factor of 2 for the higher chirp masses in a BH-NS binary as compared with NS-NS one. In short, we end up with an estimate of factor ∼40 over that calculated with NS-NS binary mergers in our Galaxy alone. Our total rate is estimated to be about one merging of compact objects per year. Our scenario of NS-NS binaries

  7. Comparative study of the electron density profiles in the compact torus plasma merging experiments

    International Nuclear Information System (INIS)

    Hayashiya, Hitoshi; Asaka, Takeo; Katsurai, Makoto

    2003-01-01

    Following two previous papers on the comparative studies of the electron density distributions for a single compact torus (CT) and a spherical tokamak (ST), and for the a single ST and a merged ST, a comparative study on the dynamics of the electron density profile and after the CT and ST plasma merging process was performed. The sharpness of the peak in the electron density profile around the mid-plane just after the merging of CT with a low safety factor (q value) such as RFP or spheromak is found to be related to the speed of the magnetic axis during the plasma merging process. It is also found that the electron density gradient near the plasma edge in a high q ST is larger than that of a low q CT. High q ST is found to be provided with the magnetic structure which is able to sustain a large thermal pressure by a strong j x B force. Despite these differences in the electron density profile between CT and ST during merging, the confinement characteristics evaluated from the number of electrons confined within the magnetic separatrix after the completion of the merging is almost similar between in the merging CT and in the merging ST. For all configurations, the electron density profiles after the completion of the merging are analogous to those of the corresponding single configuration produced without the merging process. (author)

  8. Formation of Compact Ellipticals in the merging star cluster scenario

    Science.gov (United States)

    Urrutia Zapata, Fernanda Cecilia; Theory and star formation group

    2018-01-01

    In the last years, extended old stellar clusters have been observed. They are like globular clusters (GCs) but with larger sizes(a limit of Re=10 pc is currently seen as reasonable). These extended objects (EOs) cover a huge range of mass. Objects at the low mass end with masses comparable to normal globular clusters are called extended clusters or faint fuzzies Larsen & Brodie (2000) and objects at the high-mass end are called ultra compact dwarf galaxies (UCDs). Ultra compact dwarf galaxies are compact object with luminositys above the brigtest known GCs. UCDs are more compact than typical dwarf galaxies but with comparable luminosities. Usually, a lower mass limit of 2 × 10^6 Solar masses is applied.Fellhauer & Kroupa (2002a,b) demostrated that object like ECs, FFs and UCDs can be the remnants of the merger of star clusters complexes, this scenario is called the Merging Star Cluster Scenario. Amore concise study was performed by Bruens et al. (2009, 2011).Our work tries to explain the formation of compact elliptical(cE). These objects are a comparatively rare class of spheroidal galaxies, possessing very small Re and high central surface brightnesses (Faber 1973). cEs have the same parameters as extended objects but they are slightly larger than 100 pc and the luminosities are in the range of -11 to -12 Mag.The standard formation sceanrio of these systems proposes a galaxy origin. CEs are the result of tidal stripping and truncation of nucleated larger systems. Or they could be a natural extension of the class of elliptical galaxies to lower luminosities and smaller sizes.We want to propose a completely new formation scenario for cEs. In our project we try to model cEs in a similar way that UCDs using the merging star cluster scenario extended to much higher masses and sizes. We think that in the early Universe we might have produced sufficiently strong star bursts to form cluster complexes which merge into cEs. So far it is observationally unknown if cEs are

  9. Molecular-Level Design of Heterogeneous Chiral Catalysis

    International Nuclear Information System (INIS)

    Zaera, Francisco

    2012-01-01

    The following is a proposal to continue our multi-institutional research on heterogeneous chiral catalysis. Our team combines the use of surface-sensitive analytical techniques for the characterization of model systems with quantum and statistical mechanical calculations to interpret experimental data and guide the design of future research. Our investigation focuses on the interrelation among the three main mechanisms by which enantioselectivity can be bestowed to heterogeneous catalysts, namely: (1) by templating chirality via the adsorption of chiral supramolecular assemblies, (2) by using chiral modifiers capable of forming chiral complexes with the reactant and force enantioselective surface reactions, and (3) by forming naturally chiral surfaces using imprinting chiral agents. Individually, the members of our team are leaders in these various aspects of chiral catalysis, but the present program provides the vehicle to generate and exploit the synergies necessary to address the problem in a comprehensive manner. Our initial work has advanced the methodology needed for these studies, including an enantioselective titration procedure to identify surface chiral sites, infrared spectroscopy in situ at the interface between gases or liquids and solids to mimic realistic catalytic conditions, and DFT and Monte Carlo algorithms to simulate and understand chirality on surfaces. The next step, to be funded by the monies requested in this proposal, is to apply those methods to specific problems in chiral catalysis, including the identification of the requirements for the formation of supramolecular surface structures with enantioselective behavior, the search for better molecules to probe the chiral nature of the modified surfaces, the exploration of the transition from supramolecular to one-to-one chiral modification, the correlation of the adsorption characteristics of one-to-one chiral modifiers with their physical properties, in particular with their configuration

  10. Electro-Fermentation - Merging Electrochemistry with Fermentation in Industrial Applications.

    Science.gov (United States)

    Schievano, Andrea; Pepé Sciarria, Tommy; Vanbroekhoven, Karolien; De Wever, Heleen; Puig, Sebastià; Andersen, Stephen J; Rabaey, Korneel; Pant, Deepak

    2016-11-01

    Electro-fermentation (EF) merges traditional industrial fermentation with electrochemistry. An imposed electrical field influences the fermentation environment and microbial metabolism in either a reductive or oxidative manner. The benefit of this approach is to produce target biochemicals with improved selectivity, increase carbon efficiency, limit the use of additives for redox balance or pH control, enhance microbial growth, or in some cases enhance product recovery. We discuss the principles of electrically driven fermentations and how EF can be used to steer both pure culture and microbiota-based fermentations. An overview is given on which advantages EF may bring to both existing and innovative industrial fermentation processes, and which doors might be opened in waste biomass utilization towards added-value biorefineries. Copyright © 2016 Elsevier Ltd. All rights reserved.

  11. SAR Imagery Segmentation by Statistical Region Growing and Hierarchical Merging

    Energy Technology Data Exchange (ETDEWEB)

    Ushizima, Daniela Mayumi; Carvalho, E.A.; Medeiros, F.N.S.; Martins, C.I.O.; Marques, R.C.P.; Oliveira, I.N.S.

    2010-05-22

    This paper presents an approach to accomplish synthetic aperture radar (SAR) image segmentation, which are corrupted by speckle noise. Some ordinary segmentation techniques may require speckle filtering previously. Our approach performs radar image segmentation using the original noisy pixels as input data, eliminating preprocessing steps, an advantage over most of the current methods. The algorithm comprises a statistical region growing procedure combined with hierarchical region merging to extract regions of interest from SAR images. The region growing step over-segments the input image to enable region aggregation by employing a combination of the Kolmogorov-Smirnov (KS) test with a hierarchical stepwise optimization (HSWO) algorithm for the process coordination. We have tested and assessed the proposed technique on artificially speckled image and real SAR data containing different types of targets.

  12. THE ELM SURVEY. V. MERGING MASSIVE WHITE DWARF BINARIES

    International Nuclear Information System (INIS)

    Brown, Warren R.; Kenyon, Scott J.; Kilic, Mukremin; Gianninas, A.; Allende Prieto, Carlos

    2013-01-01

    We present the discovery of 17 low-mass white dwarfs (WDs) in short-period (P ≤ 1 day) binaries. Our sample includes four objects with remarkable log g ≅ 5 surface gravities and orbital solutions that require them to be double degenerate binaries. All of the lowest surface gravity WDs have metal lines in their spectra implying long gravitational settling times or ongoing accretion. Notably, six of the WDs in our sample have binary merger times 0.9 M ☉ companions. If the companions are massive WDs, these four binaries will evolve into stable mass transfer AM CVn systems and possibly explode as underluminous supernovae. If the companions are neutron stars, then these may be millisecond pulsar binaries. These discoveries increase the number of detached, double degenerate binaries in the ELM Survey to 54; 31 of these binaries will merge within a Hubble time.

  13. The merging of Suez and 'Gaz de France'

    International Nuclear Information System (INIS)

    Anon.

    2008-01-01

    The merging of 'Gaz de France' and Suez has been approved by the shareholders on the 16 july 2008, and the decree for the privatization of 'Gaz de France' has been published to the 'Journal Officiel'. The French state will hold 35.6% of the capital of the new group GDF-Suez. The board of directors will be composed of 24 members: 7 officials from the state, 1 representative of the share-holding staff, 3 representatives of the elected employees and 13 members named by the general assembly of the shareholders. This group, which is officially born on the 22. of july 2008, is the fourth bigger group worldwide in the domain of energy. (A.C.)

  14. Merging Cultural Heritage Assessments with Risk Reduction and Disaster Recovery

    DEFF Research Database (Denmark)

    Bojsen, Ann Kristina Mikkelsen

    heritage. These limitations serve as motivation for the introduction of the ACTOR framework (Assessing Cultural Threats, Obstacles and Resilience) ACTOR aims at merging cultural heritage assessments with risk reduction and disaster recovery, and provide disaster management students with a learning......Abstract There is a general professional consensus that vulnerability and risk assessments are crucial tasks in any serious attempt to substantially reduce disaster losses and enhance the reconciliation or recovery in the post event phase. However, cultural heritage is often considered...... as an overarching element that should be assessed, rather than a permanent key component of the assessments. Research in disaster management noticeably illustrates how cultural heritage is increasingly at risk from disasters caused by natural and human-made hazards, as well as the effects of climate change. Still...

  15. Merging WW and WW+jet with MINLO

    CERN Document Server

    Hamilton, Keith; Monni, Pier Francesco; Re, Emanuele; Zanderighi, Giulia

    2016-09-12

    We present a simulation program for the production of a pair of W bosons in association with a jet, that can be used in conjunction with general-purpose shower Monte Carlo generators, according to the POWHEG method. We have further adapted and implemented the MINLO' method on top of the NLO calculation underlying our WW+jet generator. Thus, the resulting simulation achieves NLO accuracy not only for inclusive distributions in WW+jet production but also WW production, i.e. when the associated jet is not resolved, without the introduction of any unphysical merging scale. This work represents the first extension of the MINLO' method, in its original form, to the case of a genuine underlying 2->2 process, with non-trivial virtual corrections.

  16. Merging and Splitting of Plasma Spheroids in a Dusty Plasma

    Science.gov (United States)

    Mikikian, Maxime; Tawidian, Hagop; Lecas, Thomas

    2012-12-01

    Dust particle growth in a plasma is a strongly disturbing phenomenon for the plasma equilibrium. It can induce many different types of low-frequency instabilities that can be experimentally observed, especially using high-speed imaging. A spectacular case has been observed in a krypton plasma where a huge density of dust particles is grown by material sputtering. The instability consists of well-defined regions of enhanced optical emission that emerge from the electrode vicinity and propagate towards the discharge center. These plasma spheroids have complex motions resulting from their mutual interaction that can also lead to the merging of two plasma spheroids into a single one. The reverse situation is also observed with the splitting of a plasma spheroid into two parts. These results are presented for the first time and reveal new behaviors in dusty plasmas.

  17. Cleveland, Toledo utilities merge to aid N-projects

    International Nuclear Information System (INIS)

    Utroska, D.

    1985-01-01

    A decision by the Cleveland Electric Illuminating Co. and Toledo Edison to merge was spurred by the need to strengthen their access to capital markets in order to complete several nuclear power plants now under construction and to possibly mitigate the impact of large rate increases on Ohio ratepayers. The two utilities will continue as local companies. If they obtain approval from the Securities and Exchange, the Ohio Public Utilities, and the Nuclear Regulatory Commissions for the $8 million affiliation, the new holding company will be among the 20 largest electric utilities in terms of the market value of its common stock. Some industry observers see this as a harbinger of more utility mergers. 1 figure

  18. Drivers׳ merging behavior data in highway work zones

    Directory of Open Access Journals (Sweden)

    Mahmoud Shakouri

    2016-03-01

    Full Text Available There have been growing research interests in finding a suitable work zone layout to improve work zone safety and traffic efficiency. This paper contains data supporting the research article entitled: Effects of work zone configurations and traffic density on performance variables and subjective workload (Shakouri et al., 2014 [1]. A full factorial experiment was conducted to compare the efficiency of two work zone configurations by using a driving simulator with two levels of work zone configuration, two levels of traffic density and three levels of sign placement as fixed factors. Seven female and 23 male participants completed the experiment. In this paper we present the data relating to demographic information of participants, driving simulator data and subjective workload evaluation of participants for each work zone. Keywords: Work zone, Merging behavior, Subjective workload, Safety

  19. THE ELM SURVEY. V. MERGING MASSIVE WHITE DWARF BINARIES

    Energy Technology Data Exchange (ETDEWEB)

    Brown, Warren R.; Kenyon, Scott J. [Smithsonian Astrophysical Observatory, 60 Garden St, Cambridge, MA 02138 (United States); Kilic, Mukremin; Gianninas, A. [Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma, 440 W. Brooks St., Norman, OK, 73019 (United States); Allende Prieto, Carlos, E-mail: wbrown@cfa.harvard.edu, E-mail: skenyon@cfa.harvard.edu, E-mail: kilic@ou.edu, E-mail: alexg@nhn.ou.edu, E-mail: callende@iac.es [Instituto de Astrofisica de Canarias, E-38205, La Laguna, Tenerife (Spain)

    2013-05-20

    We present the discovery of 17 low-mass white dwarfs (WDs) in short-period (P {<=} 1 day) binaries. Our sample includes four objects with remarkable log g {approx_equal} 5 surface gravities and orbital solutions that require them to be double degenerate binaries. All of the lowest surface gravity WDs have metal lines in their spectra implying long gravitational settling times or ongoing accretion. Notably, six of the WDs in our sample have binary merger times <10 Gyr. Four have {approx}>0.9 M{sub Sun} companions. If the companions are massive WDs, these four binaries will evolve into stable mass transfer AM CVn systems and possibly explode as underluminous supernovae. If the companions are neutron stars, then these may be millisecond pulsar binaries. These discoveries increase the number of detached, double degenerate binaries in the ELM Survey to 54; 31 of these binaries will merge within a Hubble time.

  20. Cosmic Collisions The Hubble Atlas of Merging Galaxies

    CERN Document Server

    Christensen, Lars Lindberg; Martin, Davide

    2009-01-01

    Lars Lindberg Christensen, Raquel Yumi Shida & Davide De Martin Cosmic Collisions: The Hubble Atlas of Merging Galaxies Like majestic ships in the grandest night, galaxies can slip ever closer until their mutual gravitational interaction begins to mold them into intricate figures that are finally, and irreversibly, woven together. It is an immense cosmic dance, choreographed by gravity. Cosmic Collisions contains a hundred new, many thus far unpublished, images of colliding galaxies from the NASA/ESA Hubble Space Telescope. It is believed that many present-day galaxies, including the Milky Way, were assembled from such a coalescence of smaller galaxies, occurring over billions of years. Triggered by the colossal and violent interaction between the galaxies, stars form from large clouds of gas in firework bursts, creating brilliant blue star clusters. The importance of these cosmic encounters reaches far beyond the stunning Hubble images. They may, in fact, be among the most important processes that shape ...

  1. Is it feasible to merge data from national shoulder registries?

    DEFF Research Database (Denmark)

    Rasmussen, Jeppe V; Brorson, Stig; Hallan, Geir

    2016-01-01

    Background The Nordic Arthroplasty Register Association was initiated in 2007, and several papers about hip and knee arthroplasty have been published. Inspired by this, we aimed to examine the feasibility of merging data from the Nordic national shoulder arthroplasty registries by defining a common...... as a set of variables containing only data that all registries could deliver and where consensus according to definition of the variables could be made. Results We agreed on a data set containing patient-related data (age, gender, and diagnosis), operative data (date, arthroplasty type and brand), and data...... in case of revision (date, reason for revision, and new arthroplasty brand). From 2004 to 2013, there were 19,857 primary arthroplasties reported. The most common indications were osteoarthritis (35%) and acute fracture (34%). The number of arthroplasties and especially the number of arthroplasties...

  2. Interlayer magnetoresistance in multilayer Dirac electron systems: motion and merging of Dirac cones

    OpenAIRE

    Assili, Mohamed; Haddad, Sonia

    2013-01-01

    We theoretically study the effect of the motion and the merging of Dirac cone on the interlayer magnetoresistance in multilayer graphene like systems. This merging, which could be induced by a uniaxial strain, gives rise in monolayer Dirac electron system to a topological transition from a semi-metallic phase to an insulating phase where Dirac points disappear. Based on a universal Hamiltonian proposed to describe the motion and the merging of Dirac points in two dimensional Dirac electron cr...

  3. Merging of long-term memories in an insect.

    Science.gov (United States)

    Hunt, Kathryn L; Chittka, Lars

    2015-03-16

    Research on comparative cognition has largely focused on successes and failures of animals to solve certain cognitive tasks, but in humans, memory errors can be more complex than simple failures to retrieve information [1, 2]. The existence of various types of "false memories," in which individuals remember events that they have never actually encountered, are now well established in humans [3, 4]. We hypothesize that such systematic memory errors may be widespread in animals whose natural lifestyle involves the processing and recollection of memories for multiple stimuli [5]. We predict that memory traces for various stimuli may "merge," such that features acquired in distinct bouts of training are combined in an animal's mind, so that stimuli that have never been viewed before, but are a combination of the features presented in training, may be chosen during recall. We tested this using bumblebees, Bombus terrestris. When individuals were first trained to a solid single-colored stimulus followed by a black and white (b/w)-patterned stimulus, a subsequent preference for the last entrained stimulus was found in both short-term- and long-term-memory tests. However, when bees were first trained to b/w-patterned stimuli followed by solid single-colored stimuli and were tested in long-term-memory tests 1 or 3 days later, they only initially preferred the most recently rewarded stimulus, and then switched their preference to stimuli that combined features from the previous color and pattern stimuli. The observed merging of long-term memories is thus similar to the memory conjunction error found in humans [6]. Copyright © 2015 Elsevier Ltd. All rights reserved.

  4. Ion-electron recombination in merged-beams experiments

    International Nuclear Information System (INIS)

    Schmidt, H.T.

    1994-01-01

    In the present thesis, studies of recombination processes applying the technique of merged beams of fast ions and electrons are described. The main advantage of this technique is that the low relative velocity of ions and electrons necessary for these investigations can be achieved, at the same time as the velocity of the ions relative to the molecules of the residual gas is high. The high ion velocity leads to a very low reaction cross section for the leading contribution to the background signal, the capture of electrons in collisions with residual gas molecules. The experimental technique is described, emphasizing the electron beam velocity distribution and its relation to the energy resolution of the experiments. The presentation of the process of electron cooling is aimed at introducing this process as a tool for merged-beams experiments in storage rings rather than investigating the process itself. The non-resonant process of radiative recombination for non-fully stripped ions, showing evidence of incomplete screening is presented. Experimental investigation of dielectronic recombination is presented. Results of measurements of this process for He-like ions form the Aarhus single-pass experiment and the Heidelberg storage ring experiment are compared. Recombination is reduced from being the aim of the investigation to being a tool for high-precision measurements of the lifetimes of the 1s2s 3 S metastable states of HE-like ions of boron, carbon, and nitrogen, performed at the Heidelberg storage ring. The experiment is concerned with the process of dissociative recombination of molecular hydrogen ions. The discussion of this experiment emphasizes the distribution of population on the different vibrational levels of the ions in the initial state. In particular, a laser photo-dissociation technique was introduced to reduce the number of initial levels in the experiment. (EG) 24 refs

  5. Sparse Reconstruction of the Merging A520 Cluster System

    Energy Technology Data Exchange (ETDEWEB)

    Peel, Austin [Département d’Astrophysique, IRFU, CEA, Université Paris-Saclay, F-91191 Gif-sur-Yvette (France); Lanusse, François [McWilliams Center for Cosmology, Department of Physics, Carnegie Mellon University, Pittsburgh, PA 15213 (United States); Starck, Jean-Luc, E-mail: austin.peel@cea.fr [Université Paris Diderot, AIM, Sorbonne Paris Cité, CEA, CNRS, F-91191 Gif-sur-Yvette (France)

    2017-09-20

    Merging galaxy clusters present a unique opportunity to study the properties of dark matter in an astrophysical context. These are rare and extreme cosmic events in which the bulk of the baryonic matter becomes displaced from the dark matter halos of the colliding subclusters. Since all mass bends light, weak gravitational lensing is a primary tool to study the total mass distribution in such systems. Combined with X-ray and optical analyses, mass maps of cluster mergers reconstructed from weak-lensing observations have been used to constrain the self-interaction cross-section of dark matter. The dynamically complex Abell 520 (A520) cluster is an exceptional case, even among merging systems: multi-wavelength observations have revealed a surprising high mass-to-light concentration of dark mass, the interpretation of which is difficult under the standard assumption of effectively collisionless dark matter. We revisit A520 using a new sparsity-based mass-mapping algorithm to independently assess the presence of the puzzling dark core. We obtain high-resolution mass reconstructions from two separate galaxy shape catalogs derived from Hubble Space Telescope observations of the system. Our mass maps agree well overall with the results of previous studies, but we find important differences. In particular, although we are able to identify the dark core at a certain level in both data sets, it is at much lower significance than has been reported before using the same data. As we cannot confirm the detection in our analysis, we do not consider A520 as posing a significant challenge to the collisionless dark matter scenario.

  6. FPGA-based RF spectrum merging and adaptive hopset selection

    Science.gov (United States)

    McLean, R. K.; Flatley, B. N.; Silvius, M. D.; Hopkinson, K. M.

    The radio frequency (RF) spectrum is a limited resource. Spectrum allotment disputes stem from this scarcity as many radio devices are confined to a fixed frequency or frequency sequence. One alternative is to incorporate cognition within a reconfigurable radio platform, therefore enabling the radio to adapt to dynamic RF spectrum environments. In this way, the radio is able to actively sense the RF spectrum, decide, and act accordingly, thereby sharing the spectrum and operating in more flexible manner. In this paper, we present a novel solution for merging many distributed RF spectrum maps into one map and for subsequently creating an adaptive hopset. We also provide an example of our system in operation, the result of which is a pseudorandom adaptive hopset. The paper then presents a novel hardware design for the frequency merger and adaptive hopset selector, both of which are written in VHDL and implemented as a custom IP core on an FPGA-based embedded system using the Xilinx Embedded Development Kit (EDK) software tool. The design of the custom IP core is optimized for area, and it can process a high-volume digital input via a low-latency circuit architecture. The complete embedded system includes the Xilinx PowerPC microprocessor, UART serial connection, and compact flash memory card IP cores, and our custom map merging/hopset selection IP core, all of which are targeted to the Virtex IV FPGA. This system is then incorporated into a cognitive radio prototype on a Rice University Wireless Open Access Research Platform (WARP) reconfigurable radio.

  7. Heterogeneous Catalysis of Polyoxometalate Based Organic–Inorganic Hybrids

    Directory of Open Access Journals (Sweden)

    Yuanhang Ren

    2015-03-01

    Full Text Available Organic–inorganic hybrid polyoxometalate (POM compounds are a subset of materials with unique structures and physical/chemical properties. The combination of metal-organic coordination complexes with classical POMs not only provides a powerful way to gain multifarious new compounds but also affords a new method to modify and functionalize POMs. In parallel with the many reports on the synthesis and structure of new hybrid POM compounds, the application of these compounds for heterogeneous catalysis has also attracted considerable attention. The hybrid POM compounds show noteworthy catalytic performance in acid, oxidation, and even in asymmetric catalytic reactions. This review summarizes the design and synthesis of organic–inorganic hybrid POM compounds and particularly highlights their recent progress in heterogeneous catalysis.

  8. Value-added Chemicals from Biomass by Heterogeneous Catalysis

    DEFF Research Database (Denmark)

    Voss, Bodil

    feedstock, having retained one C-C bond originating from the biomass precursor, the aspects of utilising heterogeneous catalysis for its conversion to value added chemicals is investigated. Through a simple analysis of known, but not industrialised catalytic routes, the direct conversion of ethanol....... The results of the thesis, taking one example of biomass conversion, show that the utilisation of biomass in the production of chemicals by heterogeneous catalysis is promising from a technical point of view. But risks of market price excursions dominated by fossil based chemicals further set a criterion...... been implemented. The subject on chemical production has received less attention. This thesis describes and evaluates the quest for an alternative conversion route, based on a biomass feedstock and employing a heterogeneous catalyst capable of converting the feedstock, to a value-added chemical...

  9. Magnetic Catalysis of Chiral Symmetry Breaking: A Holographic Prospective

    International Nuclear Information System (INIS)

    Filev, V.; Rashkov, R.; Rashkov, R.

    2010-01-01

    We review a recent investigation of the effect of magnetic catalysis of mass generation in holographic Yang-Mills theories. We aim at a self-contained and pedagogical form of the review. We provide a brief field theory background and review the basics of holographic flavordynamics. The main part of the paper investigates the influence of external magnetic field to holographic gauge theories dual to the D3/D5- and D3/D7-brane intersections. Among the observed phenomena are the spontaneous breaking of a global internal symmetry, Zeeman splitting of the energy levels, and the existence of pseudo, Goldstone modes. An analytic derivation of the Gell-Mann-Oaks-Renner relation for the D3/D7 set up is reviewed. In the D3/D5 case, the pseudo-Goldstone modes satisfy nonrelativistic dispersion relation. The studies reviewed confirm the universal nature of the magnetic catalysis of mass generation.

  10. Hydrogen Tunneling Links Protein Dynamics to Enzyme Catalysis

    Science.gov (United States)

    Klinman, Judith P.; Kohen, Amnon

    2014-01-01

    The relationship between protein dynamics and function is a subject of considerable contemporary interest. Although protein motions are frequently observed during ligand binding and release steps, the contribution of protein motions to the catalysis of bond making/breaking processes is more difficult to probe and verify. Here, we show how the quantum mechanical hydrogen tunneling associated with enzymatic C–H bond cleavage provides a unique window into the necessity of protein dynamics for achieving optimal catalysis. Experimental findings support a hierarchy of thermodynamically equilibrated motions that control the H-donor and -acceptor distance and active-site electrostatics, creating an ensemble of conformations suitable for H-tunneling. A possible extension of this view to methyl transfer and other catalyzed reactions is also presented. The impact of understanding these dynamics on the conceptual framework for enzyme activity, inhibitor/drug design, and biomimetic catalyst design is likely to be substantial. PMID:23746260

  11. Homogeneous Catalysis with Metal Complexes Fundamentals and Applications

    CERN Document Server

    Duca, Gheorghe

    2012-01-01

    The book about homogeneous catalysis with metal complexes deals with the description of the reductive-oxidative, metal complexes  in a liquid phase (in polar solvents, mainly in water, and less in nonpolar solvents). The exceptional importance of the redox processes in chemical systems, in the reactions occuring in living organisms, the environmental processes, atmosphere, water, soil, and in industrial technologies (especially in food-processing industries) is discussed. The detailed practical aspects of the established regularities are explained for solving the specific practical tasks in various fields of industrial chemistry, biochemistry, medicine, analytical chemistry and ecological chemistry. The main scope of the book is the survey and systematization of the latest advances in homogeneous catalysis with metal complexes. It gives an overview of the research results and practical experience accumulated by the author during the last decade.

  12. Bionic catalysis of porphyrin for electrochemical detection of nucleic acids

    International Nuclear Information System (INIS)

    Li Jie; Lei Jianping; Wang Quanbo; Wang Peng; Ju Huangxian

    2012-01-01

    Highlights: ► This is the first application of bionic catalysis of porphyrin as detection probe in bioanalysis. ► Porphyrin–DNA–gold nanoparticle probe is synthesized. ► Binding model between FeTMPyP and DNA is verified. ► The detection probe shows excellent electrocatalytic behaviors toward the reduction of O 2 . ► The biosensor exhibited good performance with wide linear range and high specificity. - Abstract: A novel electrochemical strategy was designed for the detection of DNA based on the bionic catalysis of porphyrin. The detection probe was prepared via the assembly of thiolated double strand DNA (dsDNA) with gold nanoparticles (AuNPs), and then interacted with cationic iron (III) meso-tetrakis (N-methylphyridinum-4-yl) porphyrin (FeTMPyP) via groove binding along the dsDNA surface. The resulting nanocomplex was characterized with transmission electron microscopy, UV–vis absorption and circular dichroism spectroscopy. The FeTMPyP–DNA–AuNPs probe on gold electrode demonstrated the excellent electrocatalytic behaviors toward the reduction of O 2 due to the largely loading of FeTMPyP and good conductivity. Based on bionic catalysis of porphyrin for the reduction of O 2 , the resulting biosensor exhibited a good performance for the detection of DNA with a wide linear range from 1 × 10 −12 to 1 × 10 −8 mol L −1 and detection limit of 2.5 × 10 −13 mol L −1 at the signal/noise of 3. More importantly, the biosensor presented excellent ability to discriminate the perfectly complementary target and the mismatched stand. This strategy could be conveniently extended for detection of other biomolecules. To the best of our knowledge, this is the first application of bionic catalysis of porphyrin as detection probe and opens new opportunities for sensitive detection of biorecognition events.

  13. Heterogeneous Catalysis: Understanding for Designing, and Designing for Applications

    OpenAIRE

    Corma Canós, Avelino

    2016-01-01

    Despite the introduction of high-throughput and combinatorial methods that certainly can be useful in the process of catalysts optimization, it is recognized that the generation of fundamental knowledge at the molecular level is key for the development of new concepts and for reaching the final objective of solid catalysts by design … Corma Canós, A. (2016). Heterogeneous Catalysis: Understanding for Designing, and Designing for Applications. Angewandte Chemie International Edition. 55(21)...

  14. Cooperative catalysis by silica-supported organic functional groups

    OpenAIRE

    Margelefsky, Eric L.; Zeidan, Ryan K.; Davis, Mark E.

    2008-01-01

    Hybrid inorganic–organic materials comprising organic functional groups tethered from silica surfaces are versatile, heterogeneous catalysts. Recent advances have led to the preparation of silica materials containing multiple, different functional groups that can show cooperative catalysis; that is, these functional groups can act together to provide catalytic activity and selectivity superior to what can be obtained from either monofunctional materials or homogeneous catalysts. This tutorial...

  15. Chemistry of Fluorinated Carbon Acids: Synthesis, Physicochemical Properties, and Catalysis.

    Science.gov (United States)

    Yanai, Hikaru

    2015-01-01

    The bis[(trifluoromethyl)sulfonyl]methyl (Tf2CH; Tf=SO2CF3) group is known to be one of the strongest carbon acid functionalities. The acidity of such carbon acids in the gas phase is stronger than that of sulfuric acid. Our recent investigations have demonstrated that this type of carbon acids work as novel acid catalysts. In this paper, recent achievements in carbon acid chemistry by our research group, including synthesis, physicochemical properties, and catalysis, are summarized.

  16. Understanding plasma catalysis through modelling and simulation—a review

    International Nuclear Information System (INIS)

    Neyts, E C; Bogaerts, A

    2014-01-01

    Plasma catalysis holds great promise for environmental applications, provided that the process viability can be maximized in terms of energy efficiency and product selectivity. This requires a fundamental understanding of the various processes taking place and especially the mutual interactions between plasma and catalyst. In this review, we therefore first examine the various effects of the plasma on the catalyst and of the catalyst on the plasma that have been described in the literature. Most of these studies are purely experimental. The urgently needed fundamental understanding of the mechanisms underpinning plasma catalysis, however, may also be obtained through modelling and simulation. Therefore, we also provide here an overview of the modelling efforts that have been developed already, on both the atomistic and the macroscale, and we identify the data that can be obtained with these models to illustrate how modelling and simulation may contribute to this field. Last but not least, we also identify future modelling opportunities to obtain a more complete understanding of the various underlying plasma catalytic effects, which is needed to provide a comprehensive picture of plasma catalysis. (paper)

  17. Crown ethers and phase transfer catalysis in polymer science

    CERN Document Server

    Carraher, Charles

    1984-01-01

    Phase transfer catalysis or interfacial catalysis is a syn­ thetic technique involving transport of an organic or inorganic salt from a solid or aqueous phase into an organic liquid where reaction with an organic-soluble substrate takes place. Over the past 15 years there has been an enormous amount of effort invested in the development of this technique in organic synthe­ sis. Several books and numerous review articles have appeared summarizing applications in which low molecular weight catalysts are employed. These generally include either crown ethers or onium salts of various kinds. While the term phase transfer catalysis is relatively new, the concept of using a phasetrans­ fer agent (PTA) is much older~ Both Schnell and Morgan employed such catalysts in synthesis of polymeric species in the early 1950's. Present developments are really extensions of these early applications. It has only been within the last several years that the use of phase transfer processes have been employed in polymer synthesis...

  18. Modelling of lane-changing behaviour integrating with merging effect before a city road bottleneck

    Science.gov (United States)

    Lv, Wei; Song, Wei-guo; Fang, Zhi-ming; Ma, Jian

    2013-10-01

    Merging behaviour is a compulsive action in a discretionary lane-changing traffic system, especially in a system with a bottleneck. This paper aims to investigate the generic lane-changing behaviour considering the merging effect before a city road bottleneck. Thus firstly the merging behaviour is distinguished from other generic lane-changing behaviour. Combining discretionary lane-changing and compulsive merging, we developed an integrative traffic model, in which a method to calculate the lane-changing probability and the merging probability was proposed. A simulation scenario derived from real life was conducted to validate the proposed programming algorithm. Finally, a discussion on the simulation findings shows that the merging influence can be expanded and the merging behaviour can increase the probability of local traffic jamming in its affected area of the adjacent lane. The distribution of the merging distance provides fundamental insights for actual traffic management. The result of the clearance time implies the position of the incident point has a significant effect on the clearing time and it is important to ensure the end (exit) of the road is unimpeded in traffic evacuation.

  19. Structure-preservingness, internal merge, and the strict locality of triads

    NARCIS (Netherlands)

    Koster, J.; Karimi, S.; Samiian, V.; Wilkins, W.

    2007-01-01

    This paper examines Emonds’ Structure Preserving Hypothesis, and suggests that the insight behind this hypothesis survives reformulation in terms of recent minimalist theory: each structure created by internal merge can also, independently, be created by external merge. As before, this makes

  20. Enhanced automation of ECCS at Temelin: the merging of Eastern and Western philosophies

    International Nuclear Information System (INIS)

    Burnett, T.; Sykora, M.

    1997-01-01

    After years of separate development, the Eastern and Western concept of safety is now being merged. A significant issue in this process is the philosophy of automation versus operator action for control of safety systems. The paper discusses some aspects of this issue and presents enhancements made at Temelin which merge the Eastern and Western philosophies. (author)

  1. Virtual microscopy: merging of computer mediated communication and intuitive interfacing

    Science.gov (United States)

    de Ridder, Huib; de Ridder-Sluiter, Johanna G.; Kluin, Philip M.; Christiaans, Henri H. C. M.

    2009-02-01

    Ubiquitous computing (or Ambient Intelligence) is an upcoming technology that is usually associated with futuristic smart environments in which information is available anytime anywhere and with which humans can interact in a natural, multimodal way. However spectacular the corresponding scenarios may be, it is equally challenging to consider how this technology may enhance existing situations. This is illustrated by a case study from the Dutch medical field: central quality reviewing for pathology in child oncology. The main goal of the review is to assess the quality of the diagnosis based on patient material. The sharing of knowledge in social face-to-face interaction during such meeting is an important advantage. At the same time there is the disadvantage that the experts from the seven Dutch academic medical centers have to travel to the review meeting and that the required logistics to collect and bring patient material and data to the meeting is cumbersome and time-consuming. This paper focuses on how this time-consuming, nonefficient way of reviewing can be replaced by a virtual collaboration system by merging technology supporting Computer Mediated Collaboration and intuitive interfacing. This requires insight in the preferred way of communication and collaboration as well as knowledge about preferred interaction style with a virtual shared workspace.

  2. The Benefits of Merging Leadership Research and Emotions Research

    Science.gov (United States)

    Humphrey, Ronald H.; Burch, Gerald F.; Adams, Laural L.

    2016-01-01

    A closer merging of the literature on emotions with the research on leadership may prove advantageous to both fields. Leadership researchers will benefit by incorporating the research on emotional labor, emotional regulation, and happiness. Emotions researchers will be able to more fully consider how leadership demands influence emotional processes. In particular, researchers can better understand how the workplace context and leadership demands influence affective events. The leadership literature on charisma, transformational leadership, leader-member exchange, and other theories have the potential to shed light on how rhetorical techniques and other leadership techniques influence emotional labor, emotional contagion, moods, and overall morale. Conversely, the literature on emotional labor and emotional contagion stands to provide insights into what makes leaders charismatic, transformational, or capable of developing high quality leader–follower relationships. This review examines emotions and leadership at five levels: within person, between persons, interpersonal, groups and teams, and organizational wide and integrates research on emotions, emotional contagion, and leadership to identify opportunities for future research for both emotions researchers and leadership researchers. PMID:27458415

  3. Star Formation of Merging Disk Galaxies with AGN Feedback Effects

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jongwon; Smith, Rory; Yi, Sukyoung K., E-mail: jw.park@yonsei.ac.kr [Department of Astronomy and Yonsei University Observatory, Yonsei University, Seoul 03722 (Korea, Republic of)

    2017-08-20

    Using a numerical hydrodynamics code, we perform various idealized galaxy merger simulations to study the star formation (SF) of two merging disk galaxies. Our simulations include gas accretion onto supermassive black holes and active galactic nucleus (AGN) feedback. By comparing AGN simulations with those without AGNs, we attempt to understand when the AGN feedback effect is significant. Using ∼70 simulations, we investigate SF with the AGN effect in mergers with a variety of mass ratios, inclinations, orbits, galaxy structures, and morphologies. Using these merger simulations with AGN feedback, we measure merger-driven SF using the burst efficiency parameter introduced by Cox et al. We confirm previous studies which demonstrated that, in galaxy mergers, AGN suppresses SF more efficiently than in isolated galaxies. However, we also find that the effect of AGNs on SF is larger in major than in minor mergers. In minor merger simulations with different primary bulge-to-total ratios, the effect of bulge fraction on the merger-driven SF decreases due to AGN feedback. We create models of Sa-, Sb-, and Sc-type galaxies and compare their SF properties while undergoing mergers. With the current AGN prescriptions, the difference in merger-driven SF is not as pronounced as in the recent observational study of Kaviraj. We discuss the implications of this discrepancy.

  4. Star Formation of Merging Disk Galaxies with AGN Feedback Effects

    International Nuclear Information System (INIS)

    Park, Jongwon; Smith, Rory; Yi, Sukyoung K.

    2017-01-01

    Using a numerical hydrodynamics code, we perform various idealized galaxy merger simulations to study the star formation (SF) of two merging disk galaxies. Our simulations include gas accretion onto supermassive black holes and active galactic nucleus (AGN) feedback. By comparing AGN simulations with those without AGNs, we attempt to understand when the AGN feedback effect is significant. Using ∼70 simulations, we investigate SF with the AGN effect in mergers with a variety of mass ratios, inclinations, orbits, galaxy structures, and morphologies. Using these merger simulations with AGN feedback, we measure merger-driven SF using the burst efficiency parameter introduced by Cox et al. We confirm previous studies which demonstrated that, in galaxy mergers, AGN suppresses SF more efficiently than in isolated galaxies. However, we also find that the effect of AGNs on SF is larger in major than in minor mergers. In minor merger simulations with different primary bulge-to-total ratios, the effect of bulge fraction on the merger-driven SF decreases due to AGN feedback. We create models of Sa-, Sb-, and Sc-type galaxies and compare their SF properties while undergoing mergers. With the current AGN prescriptions, the difference in merger-driven SF is not as pronounced as in the recent observational study of Kaviraj. We discuss the implications of this discrepancy.

  5. Towards Merging Binary Integer Programming Techniques with Genetic Algorithms

    Directory of Open Access Journals (Sweden)

    Reza Zamani

    2017-01-01

    Full Text Available This paper presents a framework based on merging a binary integer programming technique with a genetic algorithm. The framework uses both lower and upper bounds to make the employed mathematical formulation of a problem as tight as possible. For problems whose optimal solutions cannot be obtained, precision is traded with speed through substituting the integrality constrains in a binary integer program with a penalty. In this way, instead of constraining a variable u with binary restriction, u is considered as real number between 0 and 1, with the penalty of Mu(1-u, in which M is a large number. Values not near to the boundary extremes of 0 and 1 make the component of Mu(1-u large and are expected to be avoided implicitly. The nonbinary values are then converted to priorities, and a genetic algorithm can use these priorities to fill its initial pool for producing feasible solutions. The presented framework can be applied to many combinatorial optimization problems. Here, a procedure based on this framework has been applied to a scheduling problem, and the results of computational experiments have been discussed, emphasizing the knowledge generated and inefficiencies to be circumvented with this framework in future.

  6. The Benefits of Merging Leadership Research and Emotions Research.

    Science.gov (United States)

    Humphrey, Ronald H; Burch, Gerald F; Adams, Laural L

    2016-01-01

    A closer merging of the literature on emotions with the research on leadership may prove advantageous to both fields. Leadership researchers will benefit by incorporating the research on emotional labor, emotional regulation, and happiness. Emotions researchers will be able to more fully consider how leadership demands influence emotional processes. In particular, researchers can better understand how the workplace context and leadership demands influence affective events. The leadership literature on charisma, transformational leadership, leader-member exchange, and other theories have the potential to shed light on how rhetorical techniques and other leadership techniques influence emotional labor, emotional contagion, moods, and overall morale. Conversely, the literature on emotional labor and emotional contagion stands to provide insights into what makes leaders charismatic, transformational, or capable of developing high quality leader-follower relationships. This review examines emotions and leadership at five levels: within person, between persons, interpersonal, groups and teams, and organizational wide and integrates research on emotions, emotional contagion, and leadership to identify opportunities for future research for both emotions researchers and leadership researchers.

  7. Image Segmentation of Cattle Muzzle Using Region Merging Statistical Technic

    Directory of Open Access Journals (Sweden)

    Jullend Gatc

    2015-12-01

    Full Text Available Making an identification system that able to assist in obtaining, recording and organizing information is the first step in developing any kind of recording system. Nowadays, many recording systems were developed with artificial markers although it has been proved that it has many limitations. Biometrics use of animals provides a solution to these restrictions. On a cattle, biometric features contained in the cattle muzzle that can be used as a pattern recognition sample. Pattern recognition methods can be used for the development of cattle identification system utilizing biometric found on the cattle muzzle using digital image processing techniques. In this study, we proposed cattle muzzle identification method using segmentation Statistical Region Merging (SRM. This method aims to identify specific patterns found on the cattle muzzle by separating the object pattern (foreground from unnecessary information (background This method is able to identified individual cattle based on the pattern of it muzzle. Based on our evaluation, this method can provide good performance results. This method good performance can be seen from the precision and recall : 87% and the value of ROC : 0.976. Hopefully this research can be used to help identify cattle accurately on the recording process.

  8. Answer Extraction Based on Merging Score Strategy of Hot Terms

    Institute of Scientific and Technical Information of China (English)

    LE Juan; ZHANG Chunxia; NIU Zhendong

    2016-01-01

    Answer extraction (AE) is one of the key technologies in developing the open domain Question&an-swer (Q&A) system . Its task is to yield the highest score to the expected answer based on an effective answer score strategy. We introduce an answer extraction method by Merging score strategy (MSS) based on hot terms. The hot terms are defined according to their lexical and syn-tactic features to highlight the role of the question terms. To cope with the syntactic diversities of the corpus, we propose four improved candidate answer score algorithms. Each of them is based on the lexical function of hot terms and their syntactic relationships with the candidate an-swers. Two independent corpus score algorithms are pro-posed to tap the role of the corpus in ranking the candi-date answers. Six algorithms are adopted in MSS to tap the complementary action among the corpus, the candi-date answers and the questions. Experiments demonstrate the effectiveness of the proposed strategy.

  9. Merging aeromagnetic data collected at different levels: the GEOMAUD survey

    Directory of Open Access Journals (Sweden)

    D. Damaske

    1999-06-01

    Full Text Available As part of the German GEOMAUD-expedition an aeromagnetic survey was carried out in Central Queen Maud Land. The helicopter-borne survey was designed in a conventional form of a regional survey with a spacing of profile-lines of 4.4 km. Due to terrain considerations - surveying from the coast across the mountain ranges to the high altitudes of the polar plateau - the survey was split into two sections flown at different constant levels. Over the coastal part survey elevation was 570 m (above sea level while for the mountain section 2845 m was chosen. Both survey parts were processed separately. The low level section was upward continued before merging with the high level section. Though this leads to a homogeneous magnetic anomaly map, in some applications it may be more advantageous to present the anomalies of the magnetic field in original survey levels as a simple combined map because small scale features are preserved and can be used in recognizing magnetic units and patterns for geological/geophysical interpretation.

  10. Three Ways to Link Merge with Hierarchical Concept-Combination

    Directory of Open Access Journals (Sweden)

    Chris Thornton

    2016-11-01

    Full Text Available In the Minimalist Program, language competence is seen to stem from a fundamental ability to construct hierarchical structure, an operation dubbed ‘Merge’. This raises the problem of how to view hierarchical concept-combination. This is a conceptual operation which also builds hierarchical structure. We can conceive of a garden that consists of a lawn and a flower-bed, for example, or a salad consisting of lettuce, fennel and rocket, or a crew consisting of a pilot and engineer. In such cases, concepts are put together in a way that makes one the accommodating element with respect to the others taken in combination. The accommodating element becomes the root of a hierarchical unit. Since this unit is itself a concept, the operation is inherently recursive. Does this mean the mind has two independent systems of hierarchical construction? Or is some form of integration more likely? Following a detailed examination of the operations involved, this paper shows there are three main ways in which Merge might be linked to hierarchical concept-combination. Also examined are the architectural implications that arise in each case.

  11. [Is merging organizations the solution to service integration?].

    Science.gov (United States)

    Demers, Louis; Dupuis, Alain; Poirier, Mario

    2002-01-01

    Organizational models inherited from the time when institutionalizing patients was common practice are now obsolete. Service coordination, undergone earlier within a same institution, is now governed by professionnals linked to various organizations and different settings. One of the difficulties of integration of these services is that contributing organizations often continue to operate individually, consequently going against the pursued goal. The solution most often proposed to counter this compartimentalization consists in reinforcing integration of organizations, which will in time favor integration of various services. One of the ways to realize this organizational integration is to reduce the number of existing organizations, by merging for example, a certain number of them. It is this path of hierarchical organization that the Québec health care system has taken during the 1990. Other paths that of networking have also been experienced during the same period. To judge of the relevance of these options, the authors propose a reversal of the dominating perspective according to which service integration necessarily pass through installing mecanisms of organizational integration. Withought minimizing the importance of such mecanisms, the authors put forth that integration of services commands first and foremost collaboration between professional health workers. Through this angle, the relevance of an organizational integration model depends on the impact it will have on the capacity and willingness of health workers to work in a concerted way. The authors submit that the fact of giving to a sole authority the govern of existing organizations is not the panacea some would like to believe.

  12. Merging Literature, Visual Art and Physics: Teaching Through Comics

    Science.gov (United States)

    Thompson, R.

    2012-12-01

    Comics have been around as a form of entertainment for decades. They are often as seen as one of the distracting vices of kids (and adults!), but comics and their more adult version, the graphic novel, are increasingly valued as a legitimate genre of both literature and visual. The APS Outreach Department has teamed up with the APS graphics department to create a series of comics, one featuring Nikola Tesla and his battles with the evil Thomas Edison, and four about laser the APS original super hero Spectra and her continuing battles with such villains as nefarious Miss Alignment and bumbling General Relativity. These comics have struck a delicate balance between education and entertainment being well received by both the comic book and education communities. By creating a compelling comic story that has correct physics, it is possible to use this under-appreciated medium to excite middle-school students who might otherwise be turned off by traditional teaching methods. In merging physics with the art of comics it is crucial to make sure first and foremost that the students enjoy the story and that they feel a connection to the characters. Students are thus hooked and once they are drawn in, the learning happens automatically.

  13. Catalysis as a foundational pillar of green chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Anastas, Paul T. [White House Office of Science and Technology Policy, Department of Chemistry, University of Nottingham Nottingham, (United Kingdom); Kirchhoff, Mary M. [U.S. Environmental Protection Agency and Trinity College, Washington, DC (United States); Williamson, Tracy C. [U.S. Environmental Protection Agency, Washington, DC (United States)

    2001-11-30

    Catalysis is one of the fundamental pillars of green chemistry, the design of chemical products and processes that reduce or eliminate the use and generation of hazardous substances. The design and application of new catalysts and catalytic systems are simultaneously achieving the dual goals of environmental protection and economic benefit. Green chemistry, the design of chemical products and processes that reduce or eliminate the use and generation of hazardous substances, is an overarching approach that is applicable to all aspects of chemistry. From feedstocks to solvents, to synthesis and processing, green chemistry actively seeks ways to produce materials in a way that is more benign to human health and the environment. The current emphasis on green chemistry reflects a shift away from the historic 'command-and-control' approach to environmental problems that mandated waste treatment and control and clean up through regulation, and toward preventing pollution at its source. Rather than accepting waste generation and disposal as unavoidable, green chemistry seeks new technologies that are cleaner and economically competitive. Utilizing green chemistry for pollution prevention demonstrates the power and beauty of chemistry: through careful design, society can enjoy the products on which we depend while benefiting the environment. The economic benefits of green chemistry are central drivers in its advancement. Industry is adopting green chemistry methodologies because they improve the corporate bottom line. A wide array of operating costs are decreased through the use of green chemistry. When less waste is generated, environmental compliance costs go down. Treatment and disposal become unnecessary when waste is eliminated. Decreased solvent usage and fewer processing steps lessen the material and energy costs of manufacturing and increase material efficiency. The environmental, human health, and the economic advantages realized through green chemistry

  14. Radio catalysis application in degradation of complex organic samples

    International Nuclear Information System (INIS)

    Moreno L, A.

    2014-01-01

    The generation of wastewater is a consequence of human activities, industries to be the generators of a large part of these discharges. These contaminated waters can be processed for their remediation; however the recalcitrant organic compounds are hardly removed through conventional treatments applied, so that new technologies have been developed for disposal such as the advanced oxidation technologies or processes. With the aim of the study is to apply ionizing radiation as a method of remediation in wastewater, in this work were carried out experiments of radiolysis and radio catalysis, which are techniques considered advanced oxidation technologies, that consist in irradiate with 60 Co gamma radiation solutions of 4- chloro phenol and methylene blue, applied at different concentrations and using as process control measurements of the compound not degraded by UV-vis spectrophotometry at 507 and 664 nm for 4-chloro phenol and methylene blue respectively. At doses greater than 2.5 kGy were near-zero degradation. Degradation experiments were also conducted by photo catalysis by irradiation with a UV lamp of 354 nm wavelength. For 4-chloro phenol results showed that degradation is efficient (39%). With those previous results, these techniques were applied to degrade complex mixtures of organic compounds from samples of wastewater from a sewage treatment plant, where was considered as process control measurement of the dissolved organic carbon obtained by a spectrophotometric analysis at 254 nm, and a maximum of 26% degradation was obtained by applying 80 kGy. On the other hand, a series of experiments fractionating the irradiations at intervals of 20 kGy to obtain a cumulative dose of 80 kGy, which was 2.8 times greater with respect to degradation by radio catalysis with continuous irradiation. (Author)

  15. Organocatalysis: Fundamentals and Comparisons to Metal and Enzyme Catalysis

    Directory of Open Access Journals (Sweden)

    Pierre Vogel

    2016-08-01

    Full Text Available Catalysis fulfills the promise that high-yielding chemical transformations will require little energy and produce no toxic waste. This message is carried by the study of the evolution of molecular catalysis of some of the most important reactions in organic chemistry. After reviewing the conceptual underpinnings of catalysis, we discuss the applications of different catalysts according to the mechanism of the reactions that they catalyze, including acyl group transfers, nucleophilic additions and substitutions, and C–C bond forming reactions that employ umpolung by nucleophilic additions to C=O and C=C double bonds. We highlight the utility of a broad range of organocatalysts other than compounds based on proline, the cinchona alkaloids and binaphthyls, which have been abundantly reviewed elsewhere. The focus is on organocatalysts, although a few examples employing metal complexes and enzymes are also included due to their significance. Classical Brønsted acids have evolved into electrophilic hands, the fingers of which are hydrogen donors (like enzymes or other electrophilic moieties. Classical Lewis base catalysts have evolved into tridimensional, chiral nucleophiles that are N- (e.g., tertiary amines, P- (e.g., tertiary phosphines and C-nucleophiles (e.g., N-heterocyclic carbenes. Many efficient organocatalysts bear electrophilic and nucleophilic moieties that interact simultaneously or not with both the electrophilic and nucleophilic reactants. A detailed understanding of the reaction mechanisms permits the design of better catalysts. Their construction represents a molecular science in itself, suggesting that sooner or later chemists will not only imitate Nature but be able to catalyze a much wider range of reactions with high chemo-, regio-, stereo- and enantioselectivity. Man-made organocatalysts are much smaller, cheaper and more stable than enzymes.

  16. Properties of Merger Shocks in Merging Galaxy Clusters

    Science.gov (United States)

    Ha, Ji-Hoon; Ryu, Dongsu; Kang, Hyesung

    2018-04-01

    X-ray shocks and radio relics detected in the cluster outskirts are commonly interpreted as shocks induced by mergers of subclumps. We study the properties of merger shocks in merging galaxy clusters, using a set of cosmological simulations for the large-scale structure formation of the universe. As a representative case, we focus on the simulated clusters that undergo almost head-on collisions with mass ratio ∼2. Due to the turbulent nature of the intracluster medium, shock surfaces are not smooth, but composed of shocks with different Mach numbers. As the merger shocks expand outward from the core to the outskirts, the average Mach number, , increases in time. We suggest that the shocks propagating along the merger axis could be manifested as X-ray shocks and/or radio relics. The kinetic energy through the shocks, F ϕ , peaks at ∼1 Gyr after their initial launching, or at ∼1–2 Mpc from the core. Because of the Mach number dependent model adopted here for the cosmic-ray (CR) acceleration efficiency, their CR-energy-weighted Mach number is higher with }CR}∼ 3{--}4, compared to the kinetic-energy-weighted Mach number, }φ ∼ 2{--}3. Most energetic shocks are to be found ahead of the lighter dark matter (DM) clump, while the heavier DM clump is located on the opposite side of clusters. Although our study is limited to the merger case considered, the results such as the means and variations of shock properties and their time evolution could be compared with the observed characteristics of merger shocks, constraining interpretations of relevant observations.

  17. Plasma Chemistry and Catalysis in Gases and Liquids

    CERN Document Server

    Parvulescu, Vasile I; Lukes, Petr

    2012-01-01

    Filling the gap for a book that not only covers gases but also plasma methods in liquids, this is all set to become the standard reference on the topic. It considers the central aspects in plasma chemistry and plasma catalysis by focusing on the green and environmental applications, while also taking into account their practical and economic viability. With the topics addressed by an international group of major experts, this is a must-have for researchers, PhD students and postdocs specializing in the field.

  18. Charge Transfer and Catalysis at the Metal Support Interface

    Energy Technology Data Exchange (ETDEWEB)

    Baker, Lawrence Robert [Univ. of California, Berkeley, CA (United States)

    2012-07-31

    Kinetic, electronic, and spectroscopic characterization of model Pt–support systems are used to demonstrate the relationship between charge transfer and catalytic activity and selectivity. The results show that charge flow controls the activity and selectivity of supported metal catalysts. This dissertation builds on extensive existing knowledge of metal–support interactions in heterogeneous catalysis. The results show the prominent role of charge transfer at catalytic interfaces to determine catalytic activity and selectivity. Further, this research demonstrates the possibility of selectively driving catalytic chemistry by controlling charge flow and presents solid-state devices and doped supports as novel methods for obtaining electronic control over catalytic reaction kinetics.

  19. Coal-related research, organic chemistry, and catalysis

    International Nuclear Information System (INIS)

    Anon.

    1980-01-01

    Coal chemistry research topics included: H exchange at 400 0 C, breaking C-C bonds in coal, molecular weight estimation using small-angle neutron scattering, 13 C NMR spectra of coals, and tunneling during H/D isotope effects. Studies of coal conversion chemistry included thermolysis of bibenzyl and 1-naphthol, heating of coals in phenol, advanced indirect liquefaction based on Koelbel slurry Fischer-Tropsch reactor, and plasma oxidation of coal minerals. Reactions of PAHs in molten SbCl 3 , a hydrocracking catalyst, were studied. Finally, heterogeneous catalysis (desulfurization etc.) was studied using Cu, Au, and Ni surfaces. 7 figures, 6 tables

  20. Molecular complexity from polyunsaturated substrates: the gold catalysis approach.

    Science.gov (United States)

    Fensterbank, Louis; Malacria, Max

    2014-03-18

    Over the last two decades, electrophilic catalysis relying on platinum(II), gold(I), and gold(III) salts has emerged as a remarkable synthetic methodology. Chemists have discovered a large variety of organic transformations that convert a great assortment of highly functionalized precursors into valuable final products. In many cases, these methodologies offer unique features, allowing access to unprecedented molecular architectures. Due to the mild reaction conditions and high function compatibility, scientists have successfully developed applications in total synthesis of natural products, as well as in asymmetric catalysis. In addition, all these developments have been accompanied by the invention of well-tailored catalysts, so that a palette of different electrophilic agents is now commercially available or readily synthesized at the bench. In some respects, researchers' interests in developing homogeneous gold catalysis can be compared with the Californian gold rush of the 19th century. It has attracted into its fervor thousands of scientists, providing a huge number of versatile and important reports. More notably, it is clear that the contribution to the art of organic synthesis is very valuable, though the quest is not over yet. Because they rely on the intervention of previously unknown types of intermediates, new retrosynthetic disconnections are now possible. In this Account, we discuss our efforts on the use of readily available polyunsaturated precursors, such as enynes, dienynes, allenynes, and allenenes to give access to highly original polycyclic structures in a single operation. These transformations transit via previously undescribed intermediates A, B, D, F, and H that will be encountered later on. All these intermediates have been determined by both ourselves and others by DFT calculations and in some cases have been confirmed on the basis of experimental data. In addition, dual gold activation can be at work in some of these transformations

  1. Inorganic Chemistry in Hydrogen Storage and Biomass Catalysis

    Energy Technology Data Exchange (ETDEWEB)

    Thorn, David [Los Alamos National Laboratory

    2012-06-13

    Making or breaking C-H, B-H, C-C bonds has been at the core of catalysis for many years. Making or breaking these bonds to store or recover energy presents us with fresh challenges, including how to catalyze these transformations in molecular systems that are 'tuned' to minimize energy loss and in molecular and material systems present in biomass. This talk will discuss some challenging transformations in chemical hydrogen storage, and some aspects of the inorganic chemistry we are studying in the development of catalysts for biomass utilization.

  2. USD Catalysis Group for Alternative Energy - Final report

    Energy Technology Data Exchange (ETDEWEB)

    Hoefelmeyer, James

    2014-10-03

    I. Project Summary Catalytic processes are a major technological underpinning of modern society, and are essential to the energy sector in the processing of chemical fuels from natural resources, fine chemicals synthesis, and energy conversion. Advances in catalyst technology are enormously valuable since these lead to reduced chemical waste, reduced energy loss, and reduced costs. New energy technologies, which are critical to future economic growth, are also heavily reliant on catalysts, including fuel cells and photo-electrochemical cells. Currently, the state of South Dakota is underdeveloped in terms of research infrastructure related to catalysis. If South Dakota intends to participate in significant economic growth opportunities that result from advances in catalyst technology, then this area of research needs to be made a high priority for investment. To this end, a focused research effort is proposed in which investigators from The University of South Dakota (USD) and The South Dakota School of Mines and Technology (SDSMT) will contribute to form the South Dakota Catalysis Group (SDCG). The multidisciplinary team of the (SDCG) include: (USD) Dan Engebretson, James Hoefelmeyer, Ranjit Koodali, and Grigoriy Sereda; (SDSMT) Phil Scott Ahrenkiel, Hao Fong, Jan Puszynski, Rajesh Shende, and Jacek Swiatkiewicz. The group is well suited to engage in a collaborative project due to the resources available within the existing programs. Activities within the SDCG will be monitored through an external committee consisting of three distinguished professors in chemistry. The committee will provide expert advice and recommendations to the SDCG. Advisory meetings in which committee members interact with South Dakota investigators will be accompanied by individual oral and poster presentations in a materials and catalysis symposium. The symposium will attract prominent scientists, and will enhance the visibility of research in the state of South Dakota. The SDCG requests

  3. Experimental evidence for collisional shock formation via two obliquely merging supersonic plasma jets

    Energy Technology Data Exchange (ETDEWEB)

    Merritt, Elizabeth C., E-mail: emerritt@lanl.gov; Adams, Colin S. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); University of New Mexico, Albuquerque, New Mexico 87131 (United States); Moser, Auna L.; Hsu, Scott C., E-mail: scotthsu@lanl.gov; Dunn, John P.; Miguel Holgado, A. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Gilmore, Mark A. [University of New Mexico, Albuquerque, New Mexico 87131 (United States)

    2014-05-15

    We report spatially resolved measurements of the oblique merging of two supersonic laboratory plasma jets. The jets are formed and launched by pulsed-power-driven railguns using injected argon, and have electron density ∼10{sup 14} cm{sup −3}, electron temperature ≈1.4 eV, ionization fraction near unity, and velocity ≈40 km/s just prior to merging. The jet merging produces a few-cm-thick stagnation layer, as observed in both fast-framing camera images and multi-chord interferometer data, consistent with collisional shock formation [E. C. Merritt et al., Phys. Rev. Lett. 111, 085003 (2013)].

  4. Computing and visualizing time-varying merge trees for high-dimensional data

    Energy Technology Data Exchange (ETDEWEB)

    Oesterling, Patrick [Univ. of Leipzig (Germany); Heine, Christian [Univ. of Kaiserslautern (Germany); Weber, Gunther H. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Morozov, Dmitry [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Scheuermann, Gerik [Univ. of Leipzig (Germany)

    2017-06-03

    We introduce a new method that identifies and tracks features in arbitrary dimensions using the merge tree -- a structure for identifying topological features based on thresholding in scalar fields. This method analyzes the evolution of features of the function by tracking changes in the merge tree and relates features by matching subtrees between consecutive time steps. Using the time-varying merge tree, we present a structural visualization of the changing function that illustrates both features and their temporal evolution. We demonstrate the utility of our approach by applying it to temporal cluster analysis of high-dimensional point clouds.

  5. On the origin of the cobalt particle size effects in Fischer−Tropsch catalysis

    NARCIS (Netherlands)

    den Breejen, J.P.|info:eu-repo/dai/nl/304837318; Radstake, P.B.|info:eu-repo/dai/nl/304829587; Bezemer, G.L.; Bitter, J.H.|info:eu-repo/dai/nl/160581435; Froseth, V.; Holmen, A.; de Jong, K.P.|info:eu-repo/dai/nl/06885580X

    2009-01-01

    The effects of metal particle size in catalysis are of prime scientific and industrial importance and call for a better understanding. In this paper the origin of the cobalt particle size effects in Fischer−Tropsch (FT) catalysis was studied. Steady-State Isotopic Transient Kinetic Analysis (SSITKA)

  6. [Prediction of common buffer catalysis in hydrolysis of fenchlorazole-ethyl].

    Science.gov (United States)

    Lin, Jing; Chen, Jing-wen; Zhang, Si-yu; Cai, Xi-yun; Qiao, Xian-liang

    2008-09-01

    The purpose of this study was to elucidate the effects of temperatures, pH levels and buffer catalysis on the hydrolysis of FCE. The hydrolysis of FCE follows first-order kinetics at different pH levels and temperatures. FCE hydrolysis rates are greatly increased at elevated pH levels and temperatures. The maximum contribution of buffer catalysis to the hydrolysis of FCE was assessed based on application of the Bronsted equations for general acid-base catalysis. The results suggest that the buffer solutions play an obvious catalysis role in hydrolysis of FCE and the hydrolysis rates of FCE are quickened by the buffer solutions. Besides, the buffer catalysis capacity of different buffer solutions is diverse, and the buffer catalysis capacity at different pH levels with the same buffer solutions is different, too. The phosphate buffer at pH = 7 shows the maximal buffer catalysis capacity. The hydrolysis rate constants of FCE as a function of temperature and pH, which were remedied by the buffer catalysis factor, were mathematically combined to predict the hydrolytic dissipation of FCE. The equation suggests that the hydrolysis half-lives of FCE ranged from 7 d to 790 d. Hydrolysis metabolites of FCE were identified by liquid chromatography-mass spectrometry. In basic conditions (pH 8-10), fenchlorazole was formed via breakdown of the ester bond of the safener.

  7. Asymmetric Aldol Additions: A Guided-Inquiry Laboratory Activity on Catalysis

    Science.gov (United States)

    King, Jorge H. Torres; Wang, Hong; Yezierski, Ellen J.

    2018-01-01

    Despite the importance of asymmetric catalysis in both the pharmaceutical and commodity chemicals industries, asymmetric catalysis is under-represented in undergraduate chemistry laboratory curricula. A novel guided-inquiry experiment based on the asymmetric aldol addition was developed. Students conduct lab work to compare the effectiveness of…

  8. Catalysis of heat-to-work conversion in quantum machines

    Science.gov (United States)

    Ghosh, A.; Latune, C. L.; Davidovich, L.; Kurizki, G.

    2017-11-01

    We propose a hitherto-unexplored concept in quantum thermodynamics: catalysis of heat-to-work conversion by quantum nonlinear pumping of the piston mode which extracts work from the machine. This concept is analogous to chemical reaction catalysis: Small energy investment by the catalyst (pump) may yield a large increase in heat-to-work conversion. Since it is powered by thermal baths, the catalyzed machine adheres to the Carnot bound, but may strongly enhance its efficiency and power compared with its noncatalyzed counterparts. This enhancement stems from the increased ability of the squeezed piston to store work. Remarkably, the fraction of piston energy that is convertible into work may then approach unity. The present machine and its counterparts powered by squeezed baths share a common feature: Neither is a genuine heat engine. However, a squeezed pump that catalyzes heat-to-work conversion by small investment of work is much more advantageous than a squeezed bath that simply transduces part of the work invested in its squeezing into work performed by the machine.

  9. Structural basis for catalysis at the membrane-water interface.

    Science.gov (United States)

    Dufrisne, Meagan Belcher; Petrou, Vasileios I; Clarke, Oliver B; Mancia, Filippo

    2017-11-01

    The membrane-water interface forms a uniquely heterogeneous and geometrically constrained environment for enzymatic catalysis. Integral membrane enzymes sample three environments - the uniformly hydrophobic interior of the membrane, the aqueous extramembrane region, and the fuzzy, amphipathic interfacial region formed by the tightly packed headgroups of the components of the lipid bilayer. Depending on the nature of the substrates and the location of the site of chemical modification, catalysis may occur in each of these environments. The availability of structural information for alpha-helical enzyme families from each of these classes, as well as several beta-barrel enzymes from the bacterial outer membrane, has allowed us to review here the different ways in which each enzyme fold has adapted to the nature of the substrates, products, and the unique environment of the membrane. Our focus here is on enzymes that process lipidic substrates. This article is part of a Special Issue entitled: Bacterial Lipids edited by Russell E. Bishop. Copyright © 2016 Elsevier B.V. All rights reserved.

  10. Acid-base catalysis of N-[(morpholine)methylene]daunorubicin.

    Science.gov (United States)

    Krause, Anna; Jelińska, Anna; Cielecka-Piontek, Judyta; Klawitter, Maria; Zalewski, Przemysław; Oszczapowicz, Irena; Wąsowska, Małgorzata

    2012-08-01

    The stability of N-[(morpholine)methylene]-daunorubicin hydrochloride (MMD) was investigated in the pH range 0.44-13.54, at 313, 308, 303 and 298 K. The degradation of MMD as a result of hydrolysis is a pseudo-first-order reaction described by the following equation: ln c = ln c(0) - k(obs)• t. In the solutions of hydrochloric acid, sodium hydroxide, borate, acetate and phosphate buffers, k(obs) = k(pH) because general acid-base catalysis was not observed. Specific acid-base catalysis of MMD comprises the following reactions: hydrolysis of the protonated molecules of MMD catalyzed by hydrogen ions (k(1)) and spontaneous hydrolysis of MMD molecules other than the protonated ones (k(2)) under the influence of water. The total rate of the reaction is equal to the sum of partial reactions: k(pH) = k(1) • a(H)+ • f(1) + k(2) • f(2) where: k(1) is the second-order rate constant (mol(-1) l s(-1)) of the specific hydrogen ion-catalyzed degradation of the protonated molecules of MMD; k(2) is the pseudo-first-order rate constant (s(-1)) of the water-catalyzed degradation of MMD molecules other than the protonated ones, f(1) - f(2) are fractions of the compound. MMD is the most stable at approx. pH 2.5.

  11. Conformational Dynamics of Thermus aquaticus DNA Polymerase I during Catalysis

    Science.gov (United States)

    Suo, Zucai

    2014-01-01

    Despite the fact that DNA polymerases have been investigated for many years and are commonly used as tools in a number of molecular biology assays, many details of the kinetic mechanism they use to catalyze DNA synthesis remain unclear. Structural and kinetic studies have characterized a rapid, pre-catalytic open-to-close conformational change of the Finger domain during nucleotide binding for many DNA polymerases including Thermus aquaticus DNA polymerase I (Taq Pol), a thermostable enzyme commonly used for DNA amplification in PCR. However, little has been done to characterize the motions of other structural domains of Taq Pol or any other DNA polymerase during catalysis. Here, we used stopped-flow Förster resonance energy transfer (FRET) to investigate the conformational dynamics of all five structural domains of the full-length Taq Pol relative to the DNA substrate during nucleotide binding and incorporation. Our study provides evidence for a rapid conformational change step induced by dNTP binding and a subsequent global conformational transition involving all domains of Taq Pol during catalysis. Additionally, our study shows that the rate of the global transition was greatly increased with the truncated form of Taq Pol lacking the N-terminal domain. Finally, we utilized a mutant of Taq Pol containing a de novo disulfide bond to demonstrate that limiting protein conformational flexibility greatly reduced the polymerization activity of Taq Pol. PMID:24931550

  12. Oxidase catalysis via aerobically generated hypervalent iodine intermediates

    Science.gov (United States)

    Maity, Asim; Hyun, Sung-Min; Powers, David C.

    2018-02-01

    The development of sustainable oxidation chemistry demands strategies to harness O2 as a terminal oxidant. Oxidase catalysis, in which O2 serves as a chemical oxidant without necessitating incorporation of oxygen into reaction products, would allow diverse substrate functionalization chemistry to be coupled to O2 reduction. Direct O2 utilization suffers from intrinsic challenges imposed by the triplet ground state of O2 and the disparate electron inventories of four-electron O2 reduction and two-electron substrate oxidation. Here, we generate hypervalent iodine reagents—a broadly useful class of selective two-electron oxidants—from O2. This is achieved by intercepting reactive intermediates of aldehyde autoxidation to aerobically generate hypervalent iodine reagents for a broad array of substrate oxidation reactions. The use of aryl iodides as mediators of aerobic oxidation underpins an oxidase catalysis platform that couples substrate oxidation directly to O2 reduction. We anticipate that aerobically generated hypervalent iodine reagents will expand the scope of aerobic oxidation chemistry in chemical synthesis.

  13. Characterization techniques for graphene-based materials in catalysis

    Directory of Open Access Journals (Sweden)

    Maocong Hu

    2017-06-01

    Full Text Available Graphene-based materials have been studied in a wide range of applications including catalysis due to the outstanding electronic, thermal, and mechanical properties. The unprecedented features of graphene-based catalysts, which are believed to be responsible for their superior performance, have been characterized by many techniques. In this article, we comprehensively summarized the characterization methods covering bulk and surface structure analysis, chemisorption ability determination, and reaction mechanism investigation. We reviewed the advantages/disadvantages of different techniques including Raman spectroscopy, X-ray photoelectron spectroscopy (XPS, Fourier transform infrared spectroscopy (FTIR and Diffuse Reflectance Fourier Transform Infrared Spectroscopy (DRIFTS, X-Ray diffraction (XRD, X-ray absorption near edge structure (XANES and X-ray absorption fine structure (XAFS, atomic force microscopy (AFM, scanning electron microscopy (SEM, transmission electron microscopy (TEM, high-resolution transmission electron microscopy (HRTEM, ultraviolet-visible spectroscopy (UV-vis, X-ray fluorescence (XRF, inductively coupled plasma mass spectrometry (ICP, thermogravimetric analysis (TGA, Brunauer–Emmett–Teller (BET, and scanning tunneling microscopy (STM. The application of temperature-programmed reduction (TPR, CO chemisorption, and NH3/CO2-temperature-programmed desorption (TPD was also briefly introduced. Finally, we discussed the challenges and provided possible suggestions on choosing characterization techniques. This review provides key information to catalysis community to adopt suitable characterization techniques for their research.

  14. The merging cluster Abell 1758: an optical and dynamical view

    Science.gov (United States)

    Monteiro-Oliveira, Rogerio; Serra Cypriano, Eduardo; Machado, Rubens; Lima Neto, Gastao B.

    2015-08-01

    The galaxy cluster Abell 1758-North (z=0.28) is a binary system composed by the sub-structures NW and NE. This is supposed to be a post-merging cluster due to observed detachment between the NE BCG and the respective X-ray emitting hot gas clump in a scenario very close to the famous Bullet Cluster. On the other hand, the projected position of the NW BCG coincides with the local hot gas peak. This system was been targeted previously by several studies, using multiple wavelengths and techniques, but there is still no clear picture of the scenario that could have caused this unusual configuration. To help solving this complex puzzle we added some pieces: firstly, we have used deep B, RC and z' Subaru images to perform both weak lensing shear and magnification analysis of A1758 (including here the South component that is not in interaction with A1758-North) modeling each sub-clump as an NFW profile in order to constrain masses and its center positions through MCMC methods; the second piece is the dynamical analysis using radial velocities available in the literature (143) plus new Gemini-GMOS/N measurements (68 new redshifts).From weak lensing we found that independent shear and magnification mass determinations are in excellent agreement between them and combining both we could reduce mass error bar by ~30% compared to shear alone. By combining this two weak-lensing probes we found that the position of both Northern BCGs are consistent with the masses centers within 2σ and and the NE hot gas peak to be offseted of the respective mass peak (M200=5.5 X 1014 M⊙) with very high significance. The most massive structure is NW (M200=7.95 X 1014 M⊙ ) where we observed no detachment between gas, DM and BCG.We have calculated a low line-of-sight velocity difference (plane of collision and the sky (<40 degrees). Dynamic modeling shows that the point of maximum approximation taken place 0.55 Gyr ago, pointing Abell 1758-North as a young merger cluster.

  15. 2009-2011 CA Coastal California TopoBathy Merged Project Digital Elevation Model (DEM)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This project merged recently collected topographic, bathymetric, and acoustic elevation data along the entire California coastline from approximately the 10 meter...

  16. 2013 NOAA Coastal California TopoBathy Merge Project Digital Elevation Model (DEM)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This project merged recently collected topographic, bathymetric, and acoustic elevation data along the entire California coastline from approximately the 10 meter...

  17. A Prospect for Evolutionary Adequacy: Merge and the Evolution and Development of Human Language

    Directory of Open Access Journals (Sweden)

    Koji Fujita

    2009-09-01

    Full Text Available Biolinguistic minimalism seeks a deeper explanation of the design, development and evolution of human language by reducing its core domain to the bare minimum including the set-formation operation Merge. In an attempt to open an avenue of research that may lead to an evolutionarily adequate theory of language, this article makes the following proposals: (i Merge is the elementary combinatorial device that requires no more decomposition; (ii the precursor to Merge may be found in the uniquely human capacity for hierarchical object manipulation; (iii the uniqueness of the human lexicon may also be captured in terms of Merge. Empirical validations of these proposals should constitute one major topic for the biolinguistic program.

  18. Developing merged CDIO based curricula for diploma (B.Eng.) IT study programs at DTU

    DEFF Research Database (Denmark)

    Nyborg, Mads; Probst, Christian W.; Stassen, Flemming

    2015-01-01

    innovation strategy. In this paper we describe the process of developing new, merged B.Eng curricula in the IT field (Diploma IT), as part of the merger between DTU Lyngby and IHK. Particular attention will be given to the following subjects: • The design process used to develop the new merged study programs......) merged with the Technical University of Denmark (DTU Lyngby). The goal of the merger was to educate ever more innovative diploma engineers to fulfill the needs by Danish industry through combining a practice-oriented development environment and a research-oriented environment. Merging a university...... institutions represented before the merger well 3500 B.Eng. students. The goal of the merger was to combine the best of the existing educations rooted in a practice-oriented development environment and a research-oriented environment. At the same time, the merger was supposed to contribute to the national...

  19. Capacity of Freeway Merge Areas with Different On-Ramp Traffic Flow

    Directory of Open Access Journals (Sweden)

    Jinxing Shen

    2015-06-01

    Full Text Available This paper is aimed at investigating the influence of different types of traffic flows on the capacity of freeway merge areas. Based on the classical gap-acceptance model, two calculating models were established specifically considering randomly arriving vehicles and individual difference in driving behaviours. Monte-Carlo simulation was implemented to reproduce the maximum traffic volume on the designed freeway merge area under different situations. The results demonstrated that the proposed calculating models have better performance than the conventional gap-acceptance theory on accurately predicting the capacity of freeway merge areas. The findings of research could be helpful to improve the microscopic traffic flow simulation model from a more practical perspective and support the designing of freeway merge areas as well.

  20. 75 FR 51825 - Quality and Compliance in Merging and Emerging Cultures; Public Conference

    Science.gov (United States)

    2010-08-23

    ... announcing a public conference entitled ``The New Paradigm: Quality and Compliance in Merging and Emerging... accommodations because of a disability, please contact Wanda Neal, at least 7 days in advance of the conference...

  1. The collaborative effect of ram pressure and merging on star formation and stripping fraction

    Science.gov (United States)

    Bischko, J. C.; Steinhauser, D.; Schindler, S.

    2015-04-01

    Aims: We investigate the effect of ram pressure stripping (RPS) on several simulations of merging pairs of gas-rich spiral galaxies. We are concerned with the changes in stripping efficiency and the time evolution of the star formation rate. Our goal is to provide an estimate of the combined effect of merging and RPS compared to the influence of the individual processes. Methods: We make use of the combined N-body/hydrodynamic code GADGET-2. The code features a threshold-based statistical recipe for star formation, as well as radiative cooling and modeling of galactic winds. In our simulations, we vary mass ratios between 1:4 and 1:8 in a binary merger. We sample different geometric configurations of the merging systems (edge-on and face-on mergers, different impact parameters). Furthermore, we vary the properties of the intracluster medium (ICM) in rough steps: the speed of the merging system relative to the ICM between 500 and 1000 km s-1, the ICM density between 10-29 and 10-27 g cm-3, and the ICM direction relative to the mergers' orbital plane. Ram pressure is kept constant within a simulation time period, as is the ICM temperature of 107 K. Each simulation in the ICM is compared to simulations of the merger in vacuum and the non-merging galaxies with acting ram pressure. Results: Averaged over the simulation time (1 Gyr) the merging pairs show a negligible 5% enhancement in SFR, when compared to single galaxies under the same environmental conditions. The SFRs peak at the time of the galaxies first fly-through. There, our simulations show SFRs of up to 20 M⊙ yr-1 (compared to 3 M⊙ yr-1 of the non-merging galaxies in vacuum). In the most extreme case, this constitutes a short-term (<50 Myr) SFR increase of 50 % over the non-merging galaxies experiencing ram pressure. The wake of merging galaxies in the ICM typically has a third to half the star mass seen in the non-merging galaxies and 5% to 10% less gas mass. The joint effect of RPS and merging, according

  2. Comparison of online and offline based merging methods for high resolution rainfall intensities

    Science.gov (United States)

    Shehu, Bora; Haberlandt, Uwe

    2016-04-01

    Accurate rainfall intensities with high spatial and temporal resolution are crucial for urban flow prediction. Commonly, raw or bias corrected radar fields are used for forecasting, while different merging products are employed for simulation. The merging products are proven to be adequate for rainfall intensities estimation, however their application in forecasting is limited as they are developed for offline mode. This study aims at adapting and refining the offline merging techniques for the online implementation, and at comparing the performance of these methods for high resolution rainfall data. Radar bias correction based on mean fields and quantile mapping are analyzed individually and also are implemented in conditional merging. Special attention is given to the impact of different spatial and temporal filters on the predictive skill of all methods. Raw radar data and kriging interpolation of station data are considered as a reference to check the benefit of the merged products. The methods are applied for several extreme events in the time period 2006-2012 caused by different meteorological conditions, and their performance is evaluated by split sampling. The study area is located within the 112 km radius of Hannover radar in Lower Saxony, Germany and the data set constitutes of 80 recording stations in 5 min time steps. The results of this study reveal how the performance of the methods is affected by the adjustment of radar data, choice of merging method and selected event. Merging techniques can be used to improve the performance of online rainfall estimation, which gives way to the application of merging products in forecasting.

  3. Optimized distributed systems achieve significant performance improvement on sorted merging of massive VCF files.

    Science.gov (United States)

    Sun, Xiaobo; Gao, Jingjing; Jin, Peng; Eng, Celeste; Burchard, Esteban G; Beaty, Terri H; Ruczinski, Ingo; Mathias, Rasika A; Barnes, Kathleen; Wang, Fusheng; Qin, Zhaohui S

    2018-06-01

    Sorted merging of genomic data is a common data operation necessary in many sequencing-based studies. It involves sorting and merging genomic data from different subjects by their genomic locations. In particular, merging a large number of variant call format (VCF) files is frequently required in large-scale whole-genome sequencing or whole-exome sequencing projects. Traditional single-machine based methods become increasingly inefficient when processing large numbers of files due to the excessive computation time and Input/Output bottleneck. Distributed systems and more recent cloud-based systems offer an attractive solution. However, carefully designed and optimized workflow patterns and execution plans (schemas) are required to take full advantage of the increased computing power while overcoming bottlenecks to achieve high performance. In this study, we custom-design optimized schemas for three Apache big data platforms, Hadoop (MapReduce), HBase, and Spark, to perform sorted merging of a large number of VCF files. These schemas all adopt the divide-and-conquer strategy to split the merging job into sequential phases/stages consisting of subtasks that are conquered in an ordered, parallel, and bottleneck-free way. In two illustrating examples, we test the performance of our schemas on merging multiple VCF files into either a single TPED or a single VCF file, which are benchmarked with the traditional single/parallel multiway-merge methods, message passing interface (MPI)-based high-performance computing (HPC) implementation, and the popular VCFTools. Our experiments suggest all three schemas either deliver a significant improvement in efficiency or render much better strong and weak scalabilities over traditional methods. Our findings provide generalized scalable schemas for performing sorted merging on genetics and genomics data using these Apache distributed systems.

  4. PEAR: a fast and accurate Illumina Paired-End reAd mergeR.

    Science.gov (United States)

    Zhang, Jiajie; Kobert, Kassian; Flouri, Tomáš; Stamatakis, Alexandros

    2014-03-01

    The Illumina paired-end sequencing technology can generate reads from both ends of target DNA fragments, which can subsequently be merged to increase the overall read length. There already exist tools for merging these paired-end reads when the target fragments are equally long. However, when fragment lengths vary and, in particular, when either the fragment size is shorter than a single-end read, or longer than twice the size of a single-end read, most state-of-the-art mergers fail to generate reliable results. Therefore, a robust tool is needed to merge paired-end reads that exhibit varying overlap lengths because of varying target fragment lengths. We present the PEAR software for merging raw Illumina paired-end reads from target fragments of varying length. The program evaluates all possible paired-end read overlaps and does not require the target fragment size as input. It also implements a statistical test for minimizing false-positive results. Tests on simulated and empirical data show that PEAR consistently generates highly accurate merged paired-end reads. A highly optimized implementation allows for merging millions of paired-end reads within a few minutes on a standard desktop computer. On multi-core architectures, the parallel version of PEAR shows linear speedups compared with the sequential version of PEAR. PEAR is implemented in C and uses POSIX threads. It is freely available at http://www.exelixis-lab.org/web/software/pear.

  5. Study of flow behaviors of droplet merging and splitting in microchannels using Micro-PIV measurement

    Science.gov (United States)

    Li, Yi; Liu, Zhaomiao

    2017-01-01

    Droplet merging and splitting are important droplet manipulations in droplet-based microfluidics. However, the fundamental flow behaviors of droplets were not systematically studied. Hence, we designed two different microstructures to achieve droplet merging and splitting respectively, and quantitatively compared different flow dynamics in different microstructures for droplet merging and splitting via micro-particle image velocimetry (micro-PIV) experiments. Some flow phenomena of droplets different from previous studies were observed during merging and splitting using a high-speed microscope. It was also found the obtained instantaneous velocity vector fields of droplets have significant influence on the droplets merging and splitting. For droplet merging, the probability of droplets coalescence (η) in a microgroove is higher (50% T-junction microchannel (15% < η < 50%), and the highest coalescence efficiency (η = 92%) comes at the two-phase flow ratio e of 0.42 in the microgroove. Moreover, compared with a cylinder obstacle, Y-junction bifurcation can split droplets more effectively and the droplet flow during splitting is steadier. The results can provide better understanding of droplet behaviors and are useful for the design and applications of droplet-based microfluidics. PMID:28890680

  6. Unravelling merging behaviors and electrostatic properties of CVD-grown monolayer MoS2 domains

    International Nuclear Information System (INIS)

    Hao, Song; Yang, Bingchu; Gao, Yongli

    2016-01-01

    The presence of grain boundaries is inevitable for chemical vapor deposition (CVD)-grown MoS 2 domains owing to various merging behaviors, which greatly limits its potential applications in novel electronic and optoelectronic devices. It is therefore of great significance to unravel the merging behaviors of the synthesized polygon shape MoS 2 domains. Here we provide systematic investigations of merging behaviors and electrostatic properties of CVD-grown polycrystalline MoS 2 crystals by multiple means. Morphological results exhibit various polygon shape features, ascribed to polycrystalline crystals merged with triangle shape MoS 2 single crystals. The thickness of triangle and polygon shape MoS 2 crystals is identical manifested by Raman intensity and peak position mappings. Three merging behaviors are proposed to illustrate the formation mechanisms of observed various polygon shaped MoS 2 crystals. The combined photoemission electron microscopy and kelvin probe force microscopy results reveal that the surface potential of perfect merged crystals is identical, which has an important implication for fabricating MoS 2 -based devices.

  7. Study of flow behaviors of droplet merging and splitting in microchannels using Micro-PIV measurement.

    Science.gov (United States)

    Shen, Feng; Li, Yi; Liu, Zhaomiao; Li, XiuJun

    2017-04-01

    Droplet merging and splitting are important droplet manipulations in droplet-based microfluidics. However, the fundamental flow behaviors of droplets were not systematically studied. Hence, we designed two different microstructures to achieve droplet merging and splitting respectively, and quantitatively compared different flow dynamics in different microstructures for droplet merging and splitting via micro-particle image velocimetry (micro-PIV) experiments. Some flow phenomena of droplets different from previous studies were observed during merging and splitting using a high-speed microscope. It was also found the obtained instantaneous velocity vector fields of droplets have significant influence on the droplets merging and splitting. For droplet merging, the probability of droplets coalescence ( η ) in a microgroove is higher (50% < η < 92%) than that in a T-junction microchannel (15% < η < 50%), and the highest coalescence efficiency ( η = 92%) comes at the two-phase flow ratio e of 0.42 in the microgroove. Moreover, compared with a cylinder obstacle, Y-junction bifurcation can split droplets more effectively and the droplet flow during splitting is steadier. The results can provide better understanding of droplet behaviors and are useful for the design and applications of droplet-based microfluidics.

  8. OPTICAL-NEAR-INFRARED COLOR GRADIENTS AND MERGING HISTORY OF ELLIPTICAL GALAXIES

    International Nuclear Information System (INIS)

    Kim, Duho; Im, Myungshin

    2013-01-01

    It has been suggested that merging plays an important role in the formation and the evolution of elliptical galaxies. While gas dissipation by star formation is believed to steepen metallicity and color gradients of the merger products, mixing of stars through dissipation-less merging (dry merging) is believed to flatten them. In order to understand the past merging history of elliptical galaxies, we studied the optical-near-infrared (NIR) color gradients of 204 elliptical galaxies. These galaxies are selected from the overlap region of the Sloan Digital Sky Survey (SDSS) Stripe 82 and the UKIRT Infrared Deep Sky Survey (UKIDSS) Large Area Survey (LAS). The use of optical and NIR data (g, r, and K) provides large wavelength baselines, and breaks the age-metallicity degeneracy, allowing us to derive age and metallicity gradients. The use of the deep SDSS Stripe 82 images makes it possible for us to examine how the color/age/metallicity gradients are related to merging features. We find that the optical-NIR color and the age/metallicity gradients of elliptical galaxies with tidal features are consistent with those of relaxed ellipticals, suggesting that the two populations underwent a similar merging history on average and that mixing of stars was more or less completed before the tidal features disappeared. Elliptical galaxies with dust features have steeper color gradients than the other two types, even after masking out dust features during the analysis, which can be due to a process involving wet merging. More importantly, we find that the scatter in the color/age/metallicity gradients of the relaxed and merging feature types decreases as their luminosities (or masses) increase at M > 10 11.4 M ☉ but stays large at lower luminosities. Mean metallicity gradients appear nearly constant over the explored mass range, but a possible flattening is observed at the massive end. According to our toy model that predicts how the distribution of metallicity gradients

  9. Contrast and Synergy between Electrocatalysis and Heterogeneous Catalysis

    Directory of Open Access Journals (Sweden)

    Andrzej Wieckowski

    2011-01-01

    Full Text Available The advances in spectroscopy and theory that have occurred over the past two decades begin to provide detailed in situ resolution of the molecular transformations that occur at both gas/metal as well as aqueous/metal interfaces. These advances begin to allow for a more direct comparison of heterogeneous catalysis and electrocatalysis. Such comparisons become important, as many of the current energy conversion strategies involve catalytic and electrocatalytic processes that occur at fluid/solid interfaces and display very similar characteristics. Herein, we compare and contrast a few different catalytic and electrocatalytic systems to elucidate the principles that cross-cut both areas and establish characteristic differences between the two with the hope of advancing both areas.

  10. REALCAT: A New Platform to Bring Catalysis to the Lightspeed

    Directory of Open Access Journals (Sweden)

    Paul Sébastien

    2015-03-01

    Full Text Available Catalysis, irrespective of its form can be considered as one of the most important pillars of today’s chemical industry. The development of new catalysts with improved performances is therefore a highly strategic issue. However, the a priori theoretical design of the best catalyst for a desired reaction is not yet possible and a time- and money-consuming experimental phase is still needed to develop a new catalyst for a given reaction. The REALCAT platform described in this paper consists in a complete, unique, integrated and top-level high-throughput technologies workflow that allows a significant acceleration of this kind of research. This is illustrated by some preliminary results of optimization of the operating conditions of glycerol dehydration to acrolein over an heteropolyacid-based supported catalyst. It is shown that using REALCAT high-throughput tools a more than 10-fold acceleration of the operating conditions optimization process is obtained.

  11. Advanced electron microscopy characterization of nanomaterials for catalysis

    Directory of Open Access Journals (Sweden)

    Dong Su

    2017-04-01

    Full Text Available Transmission electron microscopy (TEM has become one of the most powerful techniques in the fields of material science, inorganic chemistry and nanotechnology. In terms of resolutions, advanced TEM may reach a high spatial resolution of 0.05 nm, a high energy-resolution of 7 meV. In addition, in situ TEM can help researchers to image the process happened within 1 ms. This paper reviews the recent technical progresses of applying advanced TEM characterization on nanomaterials for catalysis. The text is organized based on the perspective of application: for example, size, composition, phase, strain, and morphology. The electron beam induced effect and in situ TEM are also introduced. I hope this review can help the scientists in related fields to take advantage of advanced TEM to their own researches. Keywords: Advanced TEM, Nanomaterials, Catalysts, In situ

  12. Gravitational catalysis of merons in Einstein-Yang-Mills theory

    Science.gov (United States)

    Canfora, Fabrizio; Oh, Seung Hun; Salgado-Rebolledo, Patricio

    2017-10-01

    We construct regular configurations of the Einstein-Yang-Mills theory in various dimensions. The gauge field is of meron-type: it is proportional to a pure gauge (with a suitable parameter λ determined by the field equations). The corresponding smooth gauge transformation cannot be deformed continuously to the identity. In the three-dimensional case we consider the inclusion of a Chern-Simons term into the analysis, allowing λ to be different from its usual value of 1 /2 . In four dimensions, the gravitating meron is a smooth Euclidean wormhole interpolating between different vacua of the theory. In five and higher dimensions smooth meron-like configurations can also be constructed by considering warped products of the three-sphere and lower-dimensional Einstein manifolds. In all cases merons (which on flat spaces would be singular) become regular due to the coupling with general relativity. This effect is named "gravitational catalysis of merons".

  13. Catalysis by Dust Grains in the Solar Nebula

    Science.gov (United States)

    Kress, Monika E.; Tielens, Alexander G. G. M.

    1996-01-01

    In order to determine whether grain-catalyzed reactions played an important role in the chemistry of the solar nebula, we have applied our time-dependent model of methane formation via Fischer-Tropsch catalysis to pressures from 10(exp -5) to 1 bar and temperatures from 450 to 650 K. Under these physical conditions, the reaction 3H2 + CO yields CH4 + H2O is readily catalyzed by an iron or nickel surface, whereas the same reaction is kinetically inhibited in the gas phase. Our model results indicate that under certain nebular conditions, conversion of CO to methane could be extremely efficient in the presence of iron-nickel dust grains over timescales very short compared to the lifetime of the solar nebula.

  14. Enzymatic catalysis treatment method of meat industry wastewater using lacasse.

    Science.gov (United States)

    Thirugnanasambandham, K; Sivakumar, V

    2015-01-01

    The process of meat industry produces in a large amount of wastewater that contains high levels of colour and chemical oxygen demand (COD). So they must be pretreated before their discharge into the ecological system. In this paper, enzymatic catalysis (EC) was adopted to treat the meat wastewater. Box-Behnken design (BBD), an experimental design for response surface methodology (RSM), was used to create a set of 29 experimental runs needed for optimizing of the operating conditions. Quadratic regression models with estimated coefficients were developed to describe the colour and COD removals. The experimental results show that EC could effectively reduce colour (95 %) and COD (86 %) at the optimum conditions of enzyme dose of 110 U/L, incubation time of 100 min, pH of 7 and temperature of 40 °C. RSM could be effectively adopted to optimize the operating multifactors in complex EC process.

  15. Catalysis and Downsizing in Mg-Based Hydrogen Storage Materials

    Directory of Open Access Journals (Sweden)

    Jianding Li

    2018-02-01

    Full Text Available Magnesium (Mg-based materials are promising candidates for hydrogen storage due to the low cost, high hydrogen storage capacity and abundant resources of magnesium for the realization of a hydrogen society. However, the sluggish kinetics and strong stability of the metal-hydrogen bonding of Mg-based materials hinder their application, especially for onboard storage. Many researchers are devoted to overcoming these challenges by numerous methods. Here, this review summarizes some advances in the development of Mg-based hydrogen storage materials related to downsizing and catalysis. In particular, the focus is on how downsizing and catalysts affect the hydrogen storage capacity, kinetics and thermodynamics of Mg-based hydrogen storage materials. Finally, the future development and applications of Mg-based hydrogen storage materials is discussed.

  16. Catalysis by metal-organic frameworks: fundamentals and opportunities.

    Science.gov (United States)

    Ranocchiari, Marco; van Bokhoven, Jeroen Anton

    2011-04-14

    Crystalline porous materials are extremely important for developing catalytic systems with high scientific and industrial impact. Metal-organic frameworks (MOFs) show unique potential that still has to be fully exploited. This perspective summarizes the properties of MOFs with the aim to understand what are possible approaches to catalysis with these materials. We categorize three classes of MOF catalysts: (1) those with active site on the framework, (2) those with encapsulated active species, and (3) those with active sites attached through post-synthetic modification. We identify the tunable porosity, the ability to fine tune the structure of the active site and its environment, the presence of multiple active sites, and the opportunity to synthesize structures in which key-lock bonding of substrates occurs as the characteristics that distinguish MOFs from other materials. We experience a unique opportunity to imagine and design heterogeneous catalysts, which might catalyze reactions previously thought impossible.

  17. Quantifying the limits of transition state theory in enzymatic catalysis.

    Science.gov (United States)

    Zinovjev, Kirill; Tuñón, Iñaki

    2017-11-21

    While being one of the most popular reaction rate theories, the applicability of transition state theory to the study of enzymatic reactions has been often challenged. The complex dynamic nature of the protein environment raised the question about the validity of the nonrecrossing hypothesis, a cornerstone in this theory. We present a computational strategy to quantify the error associated to transition state theory from the number of recrossings observed at the equicommittor, which is the best possible dividing surface. Application of a direct multidimensional transition state optimization to the hydride transfer step in human dihydrofolate reductase shows that both the participation of the protein degrees of freedom in the reaction coordinate and the error associated to the nonrecrossing hypothesis are small. Thus, the use of transition state theory, even with simplified reaction coordinates, provides a good theoretical framework for the study of enzymatic catalysis. Copyright © 2017 the Author(s). Published by PNAS.

  18. Cooperative catalysis with block copolymer micelles: A combinatorial approach

    KAUST Repository

    Bukhryakov, Konstantin V.

    2015-02-09

    A rapid approach to identifying complementary catalytic groups using combinations of functional polymers is presented. Amphiphilic polymers with "clickable" hydrophobic blocks were used to create a library of functional polymers, each bearing a single functionality. The polymers were combined in water, yielding mixed micelles. As the functional groups were colocalized in the hydrophobic microphase, they could act cooperatively, giving rise to new modes of catalysis. The multipolymer "clumps" were screened for catalytic activity, both in the presence and absence of metal ions. A number of catalyst candidates were identified across a wide range of model reaction types. One of the catalytic systems discovered was used to perform a number of preparative-scale syntheses. Our approach provides easy access to a range of enzyme-inspired cooperative catalysts.

  19. Molecular surface science of heterogeneous catalysis. History and perspective

    International Nuclear Information System (INIS)

    Somorjai, G.A.

    1983-08-01

    A personal account is given of how the author became involved with modern surface science and how it was employed for studies of the chemistry of surfaces and heterogeneous catalysis. New techniques were developed for studying the properties of the surface monolayers: Auger electron spectroscopy, LEED, XPS, molecular beam surface scattering, etc. An apparatus was developed and used to study hydrocarbon conversion reactions on Pt, CO hydrogenation on Rh and Fe, and NH 3 synthesis on Fe. A model has been developed for the working Pt reforming catalyst. The three molecular ingredients that control catalytic properties are atomic surface structure, an active carbonaceous deposit, and the proper oxidation state of surface atoms. 40 references, 21 figures

  20. Molecular surface science of heterogeneous catalysis. History and perspective

    Energy Technology Data Exchange (ETDEWEB)

    Somorjai, G.A.

    1983-08-01

    A personal account is given of how the author became involved with modern surface science and how it was employed for studies of the chemistry of surfaces and heterogeneous catalysis. New techniques were developed for studying the properties of the surface monolayers: Auger electron spectroscopy, LEED, XPS, molecular beam surface scattering, etc. An apparatus was developed and used to study hydrocarbon conversion reactions on Pt, CO hydrogenation on Rh and Fe, and NH/sub 3/ synthesis on Fe. A model has been developed for the working Pt reforming catalyst. The three molecular ingredients that control catalytic properties are atomic surface structure, an active carbonaceous deposit, and the proper oxidation state of surface atoms. 40 references, 21 figures. (DLC)

  1. Cooperative catalysis with block copolymer micelles: A combinatorial approach

    KAUST Repository

    Bukhryakov, Konstantin V.; Desyatkin, Victor G.; O'Shea, John Paul; Almahdali, Sarah; Solovyeva, Vera; Rodionov, Valentin

    2015-01-01

    A rapid approach to identifying complementary catalytic groups using combinations of functional polymers is presented. Amphiphilic polymers with "clickable" hydrophobic blocks were used to create a library of functional polymers, each bearing a single functionality. The polymers were combined in water, yielding mixed micelles. As the functional groups were colocalized in the hydrophobic microphase, they could act cooperatively, giving rise to new modes of catalysis. The multipolymer "clumps" were screened for catalytic activity, both in the presence and absence of metal ions. A number of catalyst candidates were identified across a wide range of model reaction types. One of the catalytic systems discovered was used to perform a number of preparative-scale syntheses. Our approach provides easy access to a range of enzyme-inspired cooperative catalysts.

  2. A solvable two-species catalysis-driven aggregation model

    CERN Document Server

    Ke Jian Hong

    2003-01-01

    We study the kinetics of a two-species catalysis-driven aggregation system, in which an irreversible aggregation between any two clusters of one species occurs only with the catalytic action of another species. By means of a generalized mean-field rate equation, we obtain the asymptotic solutions of the cluster mass distributions in a simple process with a constant rate kernel. For the case without any consumption of the catalyst, the cluster mass distribution of either species always approaches a conventional scaling law. However, the evolution behaviour of the system in the case with catalyst consumption is complicated and depends crucially on the relative data of the initial concentrations of the two species.

  3. Mesostructure-Induced Selectivity in CO2 Reduction Catalysis.

    Science.gov (United States)

    Hall, Anthony Shoji; Yoon, Youngmin; Wuttig, Anna; Surendranath, Yogesh

    2015-12-02

    Gold inverse opal (Au-IO) thin films are active for CO2 reduction to CO with high efficiency at modest overpotentials and high selectivity relative to hydrogen evolution. The specific activity for hydrogen evolution diminishes by 10-fold with increasing porous film thickness, while CO evolution activity is largely unchanged. We demonstrate that the origin of hydrogen suppression in Au-IO films stems from the generation of diffusional gradients within the pores of the mesostructured electrode rather than changes in surface faceting or Au grain size. For electrodes with optimal mesoporosity, 99% selectivity for CO evolution can be obtained at overpotentials as low as 0.4 V. These results establish electrode mesostructuring as a complementary method for tuning selectivity in CO2-to-fuels catalysis.

  4. Atomically precise cluster catalysis towards quantum controlled catalysts

    International Nuclear Information System (INIS)

    Watanabe, Yoshihide

    2014-01-01

    Catalysis of atomically precise clusters supported on a substrate is reviewed in relation to the type of reactions. The catalytic activity of supported clusters has generally been discussed in terms of electronic structure. Several lines of evidence have indicated that the electronic structure of clusters and the geometry of clusters on a support, including the accompanying cluster-support interaction, are strongly correlated with catalytic activity. The electronic states of small clusters would be easily affected by cluster–support interactions. Several studies have suggested that it is possible to tune the electronic structure through atomic control of the cluster size. It is promising to tune not only the number of cluster atoms, but also the hybridization between the electronic states of the adsorbed reactant molecules and clusters in order to realize a quantum-controlled catalyst. (review)

  5. Catalysis. Innovative applications in petrochemistry and refining. Preprints

    Energy Technology Data Exchange (ETDEWEB)

    Ernst, S.; Balfanz, U.; Jess, A.; Lercher, J.A.; Lichtscheidl, J.; Marchionna, M.; Nees, F.; Santacesaria, E. (eds.)

    2011-07-01

    Within the DGMK conference at 4th to 6th October, 2011 in Dresden (Federal Republic of Germany) the following lectures were held: (1) Developing linear-alpha-olefins technology - From laboratory to a commercial plant (A. Meiswinkel); (2) New developments in oxidation catalysis (F. Rosowski); (3) Study of the performance of vanadium based catalysts prepared by grafting in the oxidative dehydrogenation of propane (E. Santacesaria); (4) Hydrocracking for oriented conversion of heavy oils: recent trends for catalyst development (F. Bertoncini); (5) Acidic ionic liquids for n-alkane isomerization in a liquid-liquid or slurry-phase reaction mode (C. Meyer); (6) Dual catalyst system for the hydrocracking of heavy oils and residues (G. Bellussi); (7) Understanding hydrodenitrogenation on novel unsupported sulphide Mo-W-Ni catalysts (J. Hein); (8) Hydrocracking of ethyllaurate on bifunctional micro-/mesoporous composite materials (M. Adam); (9) Catalytic dehydration of ethanol to ethylene (Ying Zhu); (10) The Evonik-Uhde HPPO process for propylene oxide production (B. Jaeger); (11) A green two-step process for adipic acid production from cyclohexene: A study on parameters affecting selectivity (F. Cavani); (12) DISY: The direct synthesis of hydrogen peroxide, a bridge for innovative applications (R, Buzzoni); (13) Solid catalyst with ionic liquid layer (SCILL) - A concept to improve the selectivity of selective hydrogenations (A. Jess); (14) Co-Zn-Al based hydrotalcites as catalysts for Fischer-Tropsch process (C.L. Bianchi); (15) Honeycomb supports with high thermal conductivity for the Fischer-Tropsch synthesis (C.G. Visconti); (16) How to make Fischer-Tropsch catalyst scale-up fully reliable (L. Fischer); (17) New developments in FCC catalysis (C.P. Kelkar); (18) The potential of medium-pore zeolites for improved propene yields from catalytic cracking (F. Bager).

  6. Catalysis Science Initiative: Catalyst Design by Discovery Informatics

    Energy Technology Data Exchange (ETDEWEB)

    Delgass, William Nicholas [Purdue Univ., West Lafayette, IN (United States). Chemical Engineering; Abu-Omar, Mahdi [Purdue Univ., West Lafayette, IN (United States) Department of Chemistry; Caruthers, James [Purdue Univ., West Lafayette, IN (United States). Chemical Engineering; Ribeiro, Fabio [Purdue Univ., West Lafayette, IN (United States). Chemical Engineering; Thomson, Kendall [Purdue Univ., West Lafayette, IN (United States). Chemical Engineering; Schneider, William [Univ. of Notre Dame, IN (United States)

    2016-07-08

    Catalysts selectively enhance the rates of chemical reactions toward desired products. Such reactions provide great benefit to society in major commercial sectors such as energy production, protecting the environment, and polymer products and thereby contribute heavily to the country’s gross national product. Our premise is that the level of fundamental understanding of catalytic events at the atomic and molecular scale has reached the point that more predictive methods can be developed to shorten the cycle time to new processes. The field of catalysis can be divided into two regimes: heterogeneous and homogeneous. For the heterogeneous catalysis regime, we have used the water-gas shift (WGS) reaction (CO + H2O + CO2 + H2O) over supported metals as a test bed. Detailed analysis and strong coupling of theory with experiment have led to the following conclusions: • The sequence of elementary steps goes through a COOH intermediate • The CO binding energy is a strong function of coverage of CO adsorbed on the surface in many systems • In the case of Au catalysts, the CO adsorption is generally too weak on surface with close atomic packing, but the enhanced binding at corner atoms (which are missing bonding partners) of cubo-octahedral nanoparticles increases the energy to a near optimal value and produces very active catalysts. • Reaction on the metal alone cannot account for the experimental results. The reaction is dual functional with water activation occurring at the metal-support interface. It is clear from our work that the theory component is essential, not only for prediction of new systems, but also for reconciling data and testing hypotheses regarding potential descriptors. Particularly important is the finding that the interface between nano-sized metal particles and the oxides that are used to support them represent a new state of matter in the sense that the interfacial bonding perturbs the chemical state of both metals atoms and the support

  7. Geographically weighted regression based methods for merging satellite and gauge precipitation

    Science.gov (United States)

    Chao, Lijun; Zhang, Ke; Li, Zhijia; Zhu, Yuelong; Wang, Jingfeng; Yu, Zhongbo

    2018-03-01

    Real-time precipitation data with high spatiotemporal resolutions are crucial for accurate hydrological forecasting. To improve the spatial resolution and quality of satellite precipitation, a three-step satellite and gauge precipitation merging method was formulated in this study: (1) bilinear interpolation is first applied to downscale coarser satellite precipitation to a finer resolution (PS); (2) the (mixed) geographically weighted regression methods coupled with a weighting function are then used to estimate biases of PS as functions of gauge observations (PO) and PS; and (3) biases of PS are finally corrected to produce a merged precipitation product. Based on the above framework, eight algorithms, a combination of two geographically weighted regression methods and four weighting functions, are developed to merge CMORPH (CPC MORPHing technique) precipitation with station observations on a daily scale in the Ziwuhe Basin of China. The geographical variables (elevation, slope, aspect, surface roughness, and distance to the coastline) and a meteorological variable (wind speed) were used for merging precipitation to avoid the artificial spatial autocorrelation resulting from traditional interpolation methods. The results show that the combination of the MGWR and BI-square function (MGWR-BI) has the best performance (R = 0.863 and RMSE = 7.273 mm/day) among the eight algorithms. The MGWR-BI algorithm was then applied to produce hourly merged precipitation product. Compared to the original CMORPH product (R = 0.208 and RMSE = 1.208 mm/hr), the quality of the merged data is significantly higher (R = 0.724 and RMSE = 0.706 mm/hr). The developed merging method not only improves the spatial resolution and quality of the satellite product but also is easy to implement, which is valuable for hydrological modeling and other applications.

  8. Can survival prediction be improved by merging gene expression data sets?

    Directory of Open Access Journals (Sweden)

    Haleh Yasrebi

    Full Text Available BACKGROUND: High-throughput gene expression profiling technologies generating a wealth of data, are increasingly used for characterization of tumor biopsies for clinical trials. By applying machine learning algorithms to such clinically documented data sets, one hopes to improve tumor diagnosis, prognosis, as well as prediction of treatment response. However, the limited number of patients enrolled in a single trial study limits the power of machine learning approaches due to over-fitting. One could partially overcome this limitation by merging data from different studies. Nevertheless, such data sets differ from each other with regard to technical biases, patient selection criteria and follow-up treatment. It is therefore not clear at all whether the advantage of increased sample size outweighs the disadvantage of higher heterogeneity of merged data sets. Here, we present a systematic study to answer this question specifically for breast cancer data sets. We use survival prediction based on Cox regression as an assay to measure the added value of merged data sets. RESULTS: Using time-dependent Receiver Operating Characteristic-Area Under the Curve (ROC-AUC and hazard ratio as performance measures, we see in overall no significant improvement or deterioration of survival prediction with merged data sets as compared to individual data sets. This apparently was due to the fact that a few genes with strong prognostic power were not available on all microarray platforms and thus were not retained in the merged data sets. Surprisingly, we found that the overall best performance was achieved with a single-gene predictor consisting of CYB5D1. CONCLUSIONS: Merging did not deteriorate performance on average despite (a The diversity of microarray platforms used. (b The heterogeneity of patients cohorts. (c The heterogeneity of breast cancer disease. (d Substantial variation of time to death or relapse. (e The reduced number of genes in the merged data

  9. Optimization approaches to mpi and area merging-based parallel buffer algorithm

    Directory of Open Access Journals (Sweden)

    Junfu Fan

    Full Text Available On buffer zone construction, the rasterization-based dilation method inevitably introduces errors, and the double-sided parallel line method involves a series of complex operations. In this paper, we proposed a parallel buffer algorithm based on area merging and MPI (Message Passing Interface to improve the performances of buffer analyses on processing large datasets. Experimental results reveal that there are three major performance bottlenecks which significantly impact the serial and parallel buffer construction efficiencies, including the area merging strategy, the task load balance method and the MPI inter-process results merging strategy. Corresponding optimization approaches involving tree-like area merging strategy, the vertex number oriented parallel task partition method and the inter-process results merging strategy were suggested to overcome these bottlenecks. Experiments were carried out to examine the performance efficiency of the optimized parallel algorithm. The estimation results suggested that the optimization approaches could provide high performance and processing ability for buffer construction in a cluster parallel environment. Our method could provide insights into the parallelization of spatial analysis algorithm.

  10. Transient and intermittent magnetic reconnections in TS-3/UTST merging startup experiments

    International Nuclear Information System (INIS)

    Ono, Y.; Imazawa, R.; Imanaka, H.; Hayamizu, T.; Inomoto, M.; Sato, M.; Kawamori, E.; Ejiri, A.; Takase, Y.; Asai, T.; Takahashi, T.

    2007-01-01

    The high-power reconnection heating has been developed in the TS-3 merging experiments, leading us to a new pulsed high-beta spherical tokamak (ST) formation. Two ST plasmas were produced inductively by two or four PF coils without using any central solenoid (CS) coil and were merged together for MW-GW reconnection heating. The magnetic reconnection transformed the magnetic energy of reconnecting magnetic field through the outflow kinetic energy finally to the ion thermal energy, increasing the plasma beta of ST up to 0.5. A new finding is that ejection of current sheet (or plasmoid) causes high-speed merging/ reconnection as well as high-power heating. In the high-q ST merging, the sheet resistivity was almost classical due to the sheet thickness much longer than ion gyroradius. Large inflow flux and low current-sheet dissipation resulted in flux pileup followed by rapid growth of the current sheet. When the flux pileup exceeded a critical limit, the sheet was ejected mechanically from the squeezed X-point area. The reconnection (outflow) speed was slow during the flux pileup and was fast during the ejection, indicating that intermittent reconnection similar to the solar flare increased the averaged reconnection speed. These transient effects enable us to have the fast reconnection as well as the high-power reconnection heating, even if the merging high-q tokamaks have low current-sheet resistivity. (author)

  11. Interlayer magnetoresistance in multilayer Dirac electron systems: motion and merging of Dirac cones

    International Nuclear Information System (INIS)

    Assili, M; Haddad, S

    2013-01-01

    We theoretically study the effect of the motion and the merging of Dirac cones on the interlayer magnetoresistance in multilayer graphene-like systems. This merging, which can be induced by a uniaxial strain, gives rise in a monolayer Dirac electron system to a topological transition from a semi-metallic phase to an insulating phase whereby Dirac points disappear. Based on a universal Hamiltonian, proposed to describe the motion and the merging of Dirac points in two-dimensional Dirac electron crystals, we calculate the interlayer conductivity of a stack of deformed graphene-like layers using the Kubo formula in the quantum limit where only the contribution of the n = 0 Landau level is relevant. A crossover from a negative to a positive interlayer magnetoresistance is found to take place as the merging is approached. This sign change of the magnetoresistance can also result from a coupling between the Dirac valleys, which is enhanced as the magnetic field amplitude increases. Our results describe the behavior of the magnetotransport in the organic conductor α-(BEDT) 2 I 3 and in a stack of deformed graphene-like systems. The latter can be simulated by optical lattices or microwave experiments in which the merging of Dirac cones can be observed. (paper)

  12. Interlayer magnetoresistance in multilayer Dirac electron systems: motion and merging of Dirac cones

    Science.gov (United States)

    Assili, M.; Haddad, S.

    2013-09-01

    We theoretically study the effect of the motion and the merging of Dirac cones on the interlayer magnetoresistance in multilayer graphene-like systems. This merging, which can be induced by a uniaxial strain, gives rise in a monolayer Dirac electron system to a topological transition from a semi-metallic phase to an insulating phase whereby Dirac points disappear. Based on a universal Hamiltonian, proposed to describe the motion and the merging of Dirac points in two-dimensional Dirac electron crystals, we calculate the interlayer conductivity of a stack of deformed graphene-like layers using the Kubo formula in the quantum limit where only the contribution of the n = 0 Landau level is relevant. A crossover from a negative to a positive interlayer magnetoresistance is found to take place as the merging is approached. This sign change of the magnetoresistance can also result from a coupling between the Dirac valleys, which is enhanced as the magnetic field amplitude increases. Our results describe the behavior of the magnetotransport in the organic conductor α-(BEDT)2I3 and in a stack of deformed graphene-like systems. The latter can be simulated by optical lattices or microwave experiments in which the merging of Dirac cones can be observed.

  13. Interlayer magnetoresistance in multilayer Dirac electron systems: motion and merging of Dirac cones.

    Science.gov (United States)

    Assili, M; Haddad, S

    2013-09-11

    We theoretically study the effect of the motion and the merging of Dirac cones on the interlayer magnetoresistance in multilayer graphene-like systems. This merging, which can be induced by a uniaxial strain, gives rise in a monolayer Dirac electron system to a topological transition from a semi-metallic phase to an insulating phase whereby Dirac points disappear. Based on a universal Hamiltonian, proposed to describe the motion and the merging of Dirac points in two-dimensional Dirac electron crystals, we calculate the interlayer conductivity of a stack of deformed graphene-like layers using the Kubo formula in the quantum limit where only the contribution of the n = 0 Landau level is relevant. A crossover from a negative to a positive interlayer magnetoresistance is found to take place as the merging is approached. This sign change of the magnetoresistance can also result from a coupling between the Dirac valleys, which is enhanced as the magnetic field amplitude increases. Our results describe the behavior of the magnetotransport in the organic conductor α-(BEDT)2I3 and in a stack of deformed graphene-like systems. The latter can be simulated by optical lattices or microwave experiments in which the merging of Dirac cones can be observed.

  14. Heating properties of merging/reconnection startup of high-beta ST

    International Nuclear Information System (INIS)

    Ono, Yasushi

    2005-01-01

    The high-power reconnection heating of spherical tokamak (ST) has been studied in the TS-3 experiment by use of axial merging of two STs. In this method, the merging/magnetic reconnection transformed a part of magnetic energy of merging STs into their thermal energy within short reconnection time. Our present low-field merging (0.3-0.5kG, R∼0.2m) attained the maximum heating power of 4-10MW and increased the beta-values of STs by factor 2-3 transiently. The ion heating energy was found to increase inversely with the q-value (B t component) of two STs. The most probable cause for this dependence is fast reconnection speed/ outflow speed due to large anomalous resistivity of current sheet in low-q state. After merging startup, decrease in beta was observed especially in low-q STs, indicating that the final beta value of ST increased with the q-value. (author)

  15. Coupling chemical and biological catalysis: a flexible paradigm for producing biobased chemicals.

    Science.gov (United States)

    Schwartz, Thomas J; Shanks, Brent H; Dumesic, James A

    2016-04-01

    Advances in metabolic engineering have allowed for the development of new biological catalysts capable of selectively de-functionalizing biomass to yield platform molecules that can be upgraded to biobased chemicals using high efficiency continuous processing allowed by heterogeneous chemical catalysis. Coupling these disciplines overcomes the difficulties of selectively activating COH bonds by heterogeneous chemical catalysis and producing petroleum analogues by biological catalysis. We show that carboxylic acids, pyrones, and alcohols are highly flexible platforms that can be used to produce biobased chemicals by this approach. More generally, we suggest that molecules with three distinct functionalities may represent a practical upper limit on the extent of functionality present in the platform molecules that serve as the bridge between biological and chemical catalysis. Copyright © 2016 Elsevier Ltd. All rights reserved.

  16. Core–shell nanoparticles: synthesis and applications in catalysis and electrocatalysis

    Science.gov (United States)

    Core–shell nanoparticles (CSNs) are a class of nanostructured materials that have recently received increased attention owing to their interesting properties and broad range of applications in catalysis, biology, materials chemistry and sensors. By rationally tuning the cores as ...

  17. Ir/Sn dual-reagent catalysis towards highly selective alkylation of ...

    Indian Academy of Sciences (India)

    Wintec

    Organometallic; bimetallic; catalysis; alkylation; benzyl alcohol; iridium, tin. 1. Introduction ... cording to our proposal, the oxidative addition of tin(IV) halides across a ..... 33. 4. Conclusion. In summary, we have demonstrated here an Ir/Sn.

  18. Support for U.S. Participants at the 16th International Congress on Catalysis

    Energy Technology Data Exchange (ETDEWEB)

    Wachs, Israel E. [Lehigh Univ., Bethlehem, PA (United States)

    2017-01-17

    The enclosed report highlights the travel grant awarded to offset the cost of foreign travel of several faculty and students to attend the 16th International Congress on Catalysis (ICC) held in Beijing, China, July 3-8, 2016.

  19. Combination of sunlight irradiated oxidative processes for landfill leachate: heterogeneous catalysis (TiO2 versus homogeneous catalysis (H2O2

    Directory of Open Access Journals (Sweden)

    Oswaldo Luiz Cobra Guimarães

    2013-04-01

    Full Text Available The objective of this work was to study the treatment of landfill leachate liquid in nature, after the use of a combination of advanced oxidation processes. More specifically, it compared heterogeneous catalysis with TiO2 to homogeneous catalysis with H2O2, both under photo-irradiated sunlight. The liquid used for the study was the leachate from the landfill of the city of Cachoeira Paulista, São Paulo State, Brazil. The experiments were conducted in a semi-batch reactor open to the absorption of solar UV radiation, with 120 min reaction time. The factors and their respective levels (-1, 0 and 1 were distributed in a experimental design 24-1 with duplicate and triplicate in the central point, resulting in an array with 19 treatment trials. The studied factors in comparing the two catalytic processes were: liquid leachate dilution, TiO2 concentration on the reactor plate, the H2O2 amount and pH level. The leachate had low photo-catalytic degradability, with NOPC reductions ranging from 1% to a maximum of 24.9%. When considering each factor alone, neither homogeneous catalysis with H2O2, nor heterogeneous catalysis with TiO2, could degrade the percolated liquid without significant reductions (5% level in total NOPC. On the other hand, the combined use of homogenous catalysis with H2O2 and heterogeneous catalysis H2O2 resulted in the greatest reductions in NOPC. The optimum condition for the NOPC reduction was obtained at pH 7, dilution of percolated:water at 1:1 (v v-1 rate; excess of 12.5% H2O2 and coating plate reactor with 0.025 g cm-2 TiO2.

  20. Liquid phase oxidation via heterogeneous catalysis organic synthesis and industrial applications

    CERN Document Server

    Clerici, Mario G

    2013-01-01

    Sets the stage for environmentally friendly industrial organic syntheses From basic principles to new and emerging industrial applications, this book offers comprehensive coverage of heterogeneous liquid-phase selective oxidation catalysis. It fully examines the synthesis, characterization, and application of catalytic materials for environmentally friendly organic syntheses. Readers will find coverage of all the important classes of catalysts, with an emphasis on their stability and reusability. Liquid Phase Oxidation via Heterogeneous Catalysis features contributions from an internation

  1. Practical improvements and merging of POWHEG simulations for vector boson production

    International Nuclear Information System (INIS)

    Aliolo, Simone; Hamilton, Keith; Re, Emanuele

    2011-10-01

    In this article we generalise POWHEG next-to-leading order parton shower (NLOPS) simulations of vector boson production and vector boson production in association with a single jet, to give matrix element corrected MENLOPS simulations. In so doing we extend and provide, for the first time, an exact and faithful implementation of the MENLOPS formalism in hadronic collisions. We also consider merging the resulting event samples according to a phase space partition defined in terms of an effective jet clustering scale. The merging scale is restricted such that the component generated by the associated production simulation does not impact on the NLO accuracy of inclusive vector boson production observables. The dependence of the predictions on the unphysical merging scale is demonstrated. Comparisons with Tevatron and LHC data are presented. (orig.)

  2. An improved method for pancreas segmentation using SLIC and interactive region merging

    Science.gov (United States)

    Zhang, Liyuan; Yang, Huamin; Shi, Weili; Miao, Yu; Li, Qingliang; He, Fei; He, Wei; Li, Yanfang; Zhang, Huimao; Mori, Kensaku; Jiang, Zhengang

    2017-03-01

    Considering the weak edges in pancreas segmentation, this paper proposes a new solution which integrates more features of CT images by combining SLIC superpixels and interactive region merging. In the proposed method, Mahalanobis distance is first utilized in SLIC method to generate better superpixel images. By extracting five texture features and one gray feature, the similarity measure between two superpixels becomes more reliable in interactive region merging. Furthermore, object edge blocks are accurately addressed by re-segmentation merging process. Applying the proposed method to four cases of abdominal CT images, we segment pancreatic tissues to verify the feasibility and effectiveness. The experimental results show that the proposed method can make segmentation accuracy increase to 92% on average. This study will boost the application process of pancreas segmentation for computer-aided diagnosis system.

  3. The ionospheric footprint of antiparallel merging regions on the dayside magnetopause

    Directory of Open Access Journals (Sweden)

    I. J. Coleman

    2000-05-01

    Full Text Available The antiparallel merging hypothesis states that reconnection takes place on the dayside magnetopause where the solar and geomagnetic fields are oppositely directed. With this criterion, we have mapped the predicted merging regions to the ionosphere using the Tsyganenko 96 magnetic field model, distinguishing between regions of sub-Alfvénic and super-Alfvénic magnetosheath flow, and identifying the day-night terminator. We present the resulting shape, width and latitude of the ionospheric dayside merging regions in both hemispheres, showing their dependence on the Earth's dipole tilt. The resulting seasonal variation of the longitudinal width is consistent with the conjugate electric fields in the northern and southern cusps, as measured by the SuperDARN HF radars, for example. We also find a seasonal shift in latitude similar to that observed in satellite cusp data.Key words: Ionosphere (ionosphere-magnetosphere interactions · Magnetospheric physics (magnetopause · cusp and boundary layers; magnetosphere-ionosphere interactions

  4. Automated cloud screening of AVHRR imagery using split-and-merge clustering

    Science.gov (United States)

    Gallaudet, Timothy C.; Simpson, James J.

    1991-01-01

    Previous methods to segment clouds from ocean in AVHRR imagery have shown varying degrees of success, with nighttime approaches being the most limited. An improved method of automatic image segmentation, the principal component transformation split-and-merge clustering (PCTSMC) algorithm, is presented and applied to cloud screening of both nighttime and daytime AVHRR data. The method combines spectral differencing, the principal component transformation, and split-and-merge clustering to sample objectively the natural classes in the data. This segmentation method is then augmented by supervised classification techniques to screen clouds from the imagery. Comparisons with other nighttime methods demonstrate its improved capability in this application. The sensitivity of the method to clustering parameters is presented; the results show that the method is insensitive to the split-and-merge thresholds.

  5. MERGE-ETL: An Optimisation Equilibrium Model with Two Different Endogeneous Technological Learning Formulations

    Energy Technology Data Exchange (ETDEWEB)

    Bahn, O.; Kypreos, S.

    2002-07-01

    In MERGE-ETL, endogenous technological progress is applied to eight energy technologies: six power plants (integrated coal gasification with combined cycle, gas turbine with combined cycle, gas fuel cell, new nuclear designs, wind turbine and solar photovoltaic) and two plants producing hydrogen (from biomass and solar photovoltaic). Furthermore, compared to the original MERGE model, we have introduced two new power plants (using coal and gas) with CO{sub 2} capture and disposal into depleted oil and gas reservoirs. The difficulty with incorporating endogenous technological progress in MERGE comes from the resulting formulation of the MERGE-ETL model. Indeed, technological learning is related to increasing returns to adoption, and the mathematical formulation of MERGE-ETL corresponds then to a (non-linear and) non-convex optimisation problem. To solve MERGE-ETL, we have devised a three-step heuristic approach, where we search for the global optimum in an iterative way. We use in particular for this a linearisation, following mixed integer programming techniques, of the bottom-up part of MERGE-ETL. To study the impacts of modelling endogenous technological change in MERGE, we have considered several scenarios related to technological learning and carbon control. The latter corresponds to a 'soft landing' of world energy related CO{sub 2} emissions to a level of 10 Gt C by 2050, and takes into account the recent (2001) Marrakech Agreements for CO{sub 2} emission limits by 2010. Notice that our baseline scenario (without emission control and endogenous technological change) is consistent, in particular in terms of population and CO{sub 2} emissions, with the IPCC B2 scenario. Our numerical application with MERGE-ETL shows that technological learning yields an increase of primary energy use and of electricity generation. Indeed, energy production, and in particular electricity generation, become less expensive over-time. Energy (electricity, but also non

  6. Practical improvements and merging of POWHEG simulations for vector boson production

    Energy Technology Data Exchange (ETDEWEB)

    Aliolo, Simone [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Hamilton, Keith [Istituto Nazionale di Fisica Nucleare, Milan (Italy); Re, Emanuele [Durham Univ. (United Kingdom). Dept. of Physics

    2011-10-15

    In this article we generalise POWHEG next-to-leading order parton shower (NLOPS) simulations of vector boson production and vector boson production in association with a single jet, to give matrix element corrected MENLOPS simulations. In so doing we extend and provide, for the first time, an exact and faithful implementation of the MENLOPS formalism in hadronic collisions. We also consider merging the resulting event samples according to a phase space partition defined in terms of an effective jet clustering scale. The merging scale is restricted such that the component generated by the associated production simulation does not impact on the NLO accuracy of inclusive vector boson production observables. The dependence of the predictions on the unphysical merging scale is demonstrated. Comparisons with Tevatron and LHC data are presented. (orig.)

  7. Modeling the Compression of Merged Compact Toroids by Multiple Plasma Jets

    Science.gov (United States)

    Thio, Y. C. Francis; Knapp, Charles E.; Kirkpatrick, Ron; Rodgers, Stephen L. (Technical Monitor)

    2000-01-01

    A fusion propulsion scheme has been proposed that makes use of the merging of a spherical distribution of plasma jets to dynamically form a gaseous liner. The gaseous liner is used to implode a magnetized target to produce the fusion reaction in a standoff manner. In this paper, the merging of the plasma jets to form the gaseous liner is investigated numerically. The Los Alamos SPHINX code, based on the smoothed particle hydrodynamics method is used to model the interaction of the jets. 2-D and 3-D simulations have been performed to study the characteristics of the resulting flow when these jets collide. The results show that the jets merge to form a plasma liner that converge radially which may be used to compress the central plasma to fusion conditions. Details of the computational model and the SPH numerical methods will be presented together with the numerical results.

  8. Estimation of Airline Benefits from Avionics Upgrade under Preferential Merge Re-sequence Scheduling

    Science.gov (United States)

    Kotegawa, Tatsuya; Cayabyab, Charlene Anne; Almog, Noam

    2013-01-01

    Modernization of the airline fleet avionics is essential to fully enable future technologies and procedures for increasing national airspace system capacity. However in the current national airspace system, system-wide benefits gained by avionics upgrade are not fully directed to aircraft/airlines that upgrade, resulting in slow fleet modernization rate. Preferential merge re-sequence scheduling is a best-equipped-best-served concept designed to incentivize avionics upgrade among airlines by allowing aircraft with new avionics (high-equipped) to be re-sequenced ahead of aircraft without the upgrades (low-equipped) at enroute merge waypoints. The goal of this study is to investigate the potential benefits gained or lost by airlines under a high or low-equipped fleet scenario if preferential merge resequence scheduling is implemented.

  9. On the merging rates of envelope-deprived components of binary systems which can give rise to supernova events

    International Nuclear Information System (INIS)

    Tornambe, Amedo

    1989-01-01

    We derive theoretical rates of mergings of envelope-deprived components of binary systems, which can give rise to supernova events. The effects of the various assumptions one is forced to make on the physical properties of the progenitor system and of its evolutionary behaviour through common envelope phases are discussed. Four cases have been analysed: CO-CO, He-CO, He-He double degenerate mergings and He star-CO dwarf merging. (author)

  10. Cold pool organization and the merging of convective updrafts in a Large Eddy Simulation

    Science.gov (United States)

    Glenn, I. B.; Krueger, S. K.

    2016-12-01

    Cold pool organization is a process that accelerates the transition from shallow to deep cumulus convection, and leads to higher deep convective cloud top heights. The mechanism by which cold pool organization enhances convection remains not well understood, but the basic idea is that since precipitation evaporation and a low equivalent potential temperature in the mid-troposphere lead to strong cold pools, the net cold pool effect can be accounted for in a cumulus parameterization as a relationship involving those factors. Understanding the actual physical mechanism at work will help quantify the strength of the relationship between cold pools and enhanced deep convection. One proposed mechanism of enhancement is that cold pool organization leads to reduced distances between updrafts, creating a local environment more conducive to convection as updrafts entrain parcels of air recently detrained by their neighbors. We take this hypothesis one step further and propose that convective updrafts actually merge, not just exchange recently processed air. Because entrainment and detrainment around an updraft draws nearby air in or pushes it out, respectively, they act like dynamic flow sources and sinks, drawing each other in or pushing each other away. The acceleration is proportional to the inverse square of the distance between two updrafts, so a small reduction in distance can make a big difference in the rate of merging. We have shown in previous research how merging can be seen as collisions between different updraft air parcels using Lagrangian Parcel Trajectories (LPTs) released in a Large Eddy Simulation (LES) during a period with organized deep convection. Now we use a Eulerian frame of reference to examine the updraft merging process during the transition from shallow to organized deep convection. We use a case based on the Large-Scale Biosphere-Atmosphere Experiment in Amazonia (LBA) for our LES. We directly measure the rate of entrainment and the properties

  11. High-power heating experiment of spherical tokamaks by use of plasma merging

    International Nuclear Information System (INIS)

    Ueda, Yoshinobu; Ono, Yasushi

    1999-01-01

    High-power heating of spherical tokamaks (STs) has been investigated experimentally by use of plasma merging effect. When two STs were coaxially collided, thermal energy of a colliding ST was injected into a target ST during short reconnection time (Alfven time). Though the thermal energy increment increased with decreasing plasma q value, thermal energy loss during the following relaxation, tended to be smaller with increasing q. The produced high-β STs had hallower current profiles and weaker paramagnetic toroidal field than those of single STs. Those heating properties indicate the plasma merging to be a promising initial heating method of ST plasmas. (author)

  12. Photocatalytic Arylation of Alkenes, Alkynes and Enones with Diazonium Salts

    OpenAIRE

    Schroll, Peter; Hari, Durga Prasad; König, Burkhard

    2012-01-01

    Teaching old dogs new tricks: Visible light photoredox catalysis improves the classic Meerwein arylation protocol significantly and allows the light-controlled arylation of alkenes, alkynes and enones by diazonium salts.

  13. Hydrogen and methane synthesis through radiation catalysis. Final report

    International Nuclear Information System (INIS)

    DuBow, J.

    1980-09-01

    The goal of this research was to evaluate the potential for using reactor wastes to synthesize useful products in quasi-photochemical configuration. It was found that semiconductor oxides act as heterogenous catalysts for the formation of H 2 in aqueous media under 60 Co irradiation. The principle of a gamma-ray solar cell was demonstrated experimentally. Experiments with ultraviolet irradiated TiO 2 and ZnO grains demonstrated that both H 2 and H 2 O 2 were formed, in contrast to the results of work by previous authors. These results were rationalized by energy band diagram representations and by applying principles of semiconductor photoelectrochemistry. The concept of gamma-ray assisted desulfurization of coal through radiological degradation and heterogenous catalysis was experimentally demonstrated. The proof-of-concept experiments in the present study provide the basis for further fundamental and applied investigations, particularly in a potentially efficient system with a fresh source and 1.5 m path length

  14. Gold Nanofilm Redox Catalysis for Oxygen Reduction at Soft Interfaces

    International Nuclear Information System (INIS)

    Smirnov, Evgeny; Peljo, Pekka; Scanlon, Micheál D.; Girault, Hubert H.

    2016-01-01

    ABSTRACT: Functionalization of a soft or liquid-liquid interface by a one gold nanoparticle thick “nanofilm” provides a conductive pathway to facilitate interfacial electron transfer from a lipophilic electron donor to a hydrophilic electron acceptor in a process known as interfacial redox catalysis. The gold nanoparticles in the nanofilm are charged by Fermi level equilibration with the lipophilic electron donor and act as an interfacial reservoir of electrons. Additional thermodynamic driving force can be provided by electrochemically polarising the interface. Using these principles, the biphasic reduction of oxygen by a lipophilic electron donor, decamethylferrocene, dissolved in α,α,α-trifluorotoluene was catalysed at a gold nanoparticle nanofilm modified water-oil interface. A recently developed microinjection technique was utilised to modify the interface reproducibly with the mirror-like gold nanoparticle nanofilm, while the oxidised electron donor species and the reduction product, hydrogen peroxide, were detected by ion transfer voltammetry and UV/vis spectroscopy, respectively. Metallization of the soft interface allowed the biphasic oxygen reduction reaction to proceed via an alternative mechanism with enhanced kinetics and at a significantly lower overpotential in comparison to a bare soft interface. Weaker lipophilic reductants, such as ferrocene, were capable of charging the interfacial gold nanoparticle nanofilm but did not have sufficient thermodynamic driving force to significantly elicit biphasic oxygen reduction.

  15. Bacterial and Fungal Proteolytic Enzymes: Production, Catalysis and Potential Applications.

    Science.gov (United States)

    da Silva, Ronivaldo Rodrigues

    2017-09-01

    Submerged and solid-state bioprocesses have been extensively explored worldwide and employed in a number of important studies dealing with microbial cultivation for the production of enzymes. The development of these production technologies has facilitated the generation of new enzyme-based products with applications in pharmaceuticals, food, bioactive peptides, and basic research studies, among others. The applicability of microorganisms in biotechnology is potentiated because of their various advantages, including large-scale production, short time of cultivation, and ease of handling. Currently, several studies are being conducted to search for new microbial peptidases with peculiar biochemical properties for industrial applications. Bioprospecting, being an important prerequisite for research and biotechnological development, is based on exploring the microbial diversity for enzyme production. Limited information is available on the production of specific proteolytic enzymes from bacterial and fungal species, especially on the subgroups threonine and glutamic peptidases, and the seventh catalytic type, nonhydrolytic asparagine peptide lyase. This gap in information motivated the present study about these unique biocatalysts. In this study, the biochemical and biotechnological aspects of the seven catalytic types of proteolytic enzymes, namely aspartyl, cysteine, serine, metallo, glutamic, and threonine peptidase, and asparagine peptide lyase, are summarized, with an emphasis on new studies, production, catalysis, and application of these enzymes.

  16. Mineral catalysis of oil producing reactions in coal liquefaction

    Energy Technology Data Exchange (ETDEWEB)

    Shridharani, K.G.

    1983-01-01

    This work was concerned primarily with the development of a relatively inexpensive, readily available, high activity catalyst that can be used as a disposable catalyst in coal liquefaction processes. For a fair evaluation of the developmental mineral catalyst (presulfided iron oxide), it was necessary to determine at different stages of this work, whether catalyst inhibition, deactivation or activity was the limiting factor in coal liquefaction catalysis. First, different routes were explored to prepare a high hydrogenation activity, iron-based catalyst. Naphthalene hydrogenation was used as a model reaction to rate the hydrogenation activities of different additives. Presulfiding of iron oxide with H/sub 2/S, under controlled conditions, rendered the highest hydrogenation activity mineral catalyst, which had a hydrogenation activity even greater than that of commercial CoMo/Al/sub 2/O/sub 3/ catalyst sulfided with creosote oil and hydrogen. Sulfiding of CoMo/Al/sub 2/O/sub 3/ catalyst with H/sub 2/S remarkably improved its initial hydrogenation activity. Second, the catalyst inhibition and deactivation during liquefaction were studied. Liquefaction-process solvents contain a number of compounds that can either deactivate or inhibit the hydrogenation activity of a catalyst. Finally, the hydrocracking activity of the presulfided iron oxide catalyst was compared with that of commercial catalysts, CoMo/Al/sub 2/O/sub 3/ and low alumina FCC catalyst.

  17. Ferroelectrics: A pathway to switchable surface chemistry and catalysis

    Science.gov (United States)

    Kakekhani, Arvin; Ismail-Beigi, Sohrab; Altman, Eric I.

    2016-08-01

    It has been known for more than six decades that ferroelectricity can affect a material's surface physics and chemistry thereby potentially enhancing its catalytic properties. Ferroelectrics are a class of materials with a switchable electrical polarization that can affect surface stoichiometry and electronic structure and thus adsorption energies and modes; e.g., molecular versus dissociative. Therefore, ferroelectrics may be utilized to achieve switchable surface chemistry whereby surface properties are not fixed but can be dynamically controlled by, for example, applying an external electric field or modulating the temperature. Several important examples of applications of ferroelectric and polar materials in photocatalysis and heterogeneous catalysis are discussed. In photocatalysis, the polarization direction can control band bending at water/ferroelectric and ferroelectric/semiconductor interfaces, thereby facilitating charge separation and transfer to the electrolyte and enhancing photocatalytic activity. For gas-surface interactions, available results suggest that using ferroelectrics to support catalytically active transition metals and oxides is another way to enhance catalytic activity. Finally, the possibility of incorporating ferroelectric switching into the catalytic cycle itself is described. In this scenario, a dynamic collaboration of two polarization states can be used to drive reactions that have been historically challenging to achieve on surfaces with fixed chemical properties (e.g., direct NOx decomposition and the selective partial oxidation of methane). These predictions show that dynamic modulation of the polarization can help overcome some of the fundamental limitations on catalytic activity imposed by the Sabatier principle.

  18. Anatomy of the magnetic catalysis by renormalization-group method

    Science.gov (United States)

    Hattori, Koichi; Itakura, Kazunori; Ozaki, Sho

    2017-12-01

    We first examine the scaling argument for a renormalization-group (RG) analysis applied to a system subject to the dimensional reduction in strong magnetic fields, and discuss the fact that a four-Fermi operator of the low-energy excitations is marginal irrespective of the strength of the coupling constant in underlying theories. We then construct a scale-dependent effective four-Fermi interaction as a result of screened photon exchanges at weak coupling, and establish the RG method appropriately including the screening effect, in which the RG evolution from ultraviolet to infrared scales is separated into two stages by the screening-mass scale. Based on a precise agreement between the dynamical mass gaps obtained from the solutions of the RG and Schwinger-Dyson equations, we discuss an equivalence between these two approaches. Focusing on QED and Nambu-Jona-Lasinio model, we clarify how the properties of the interactions manifest themselves in the mass gap, and point out an importance of respecting the intrinsic energy-scale dependences in underlying theories for the determination of the mass gap. These studies are expected to be useful for a diagnosis of the magnetic catalysis in QCD.

  19. Retinal Photoisomerization in Rhodopsin: Electrostatic and Steric Catalysis

    International Nuclear Information System (INIS)

    Tomasello, Gaia; Altoe, Piero; Stenta, Marco; Olaso-Gonzalez, Gloria; Garavelli, Marco; Orlandi, Giorgio

    2007-01-01

    Excited state QM(CASPT2//CASSCF)/MM(GAFF) calculations, by our recently developed code COBRAMM (Computations at Bologna Relating Ab-initio and Molecular Mechanic Methods), were carried out in rhodopsin to investigate on the steric and electrostatic effects in retinal photoisomerization catalysis due to the β-ionone ring and glutammate 181 (GLU 181), respectively. The excited state photoisomerization channel has been mapped and a new christallographyc structure (2.2 Aa resolution) has been used for this purpose. Two different set-ups have been used to evaluate the electrostatic effects of GLU 181 (which is very close to the central double bond of the chromophore): the first with a neutral GLU 181 (as commonly accepted), the second with a negatively charged (i.e. deprotonated) GLU 181 (as very recent experimental findings seem to suggest). On the other hand, β-ionone ring steric effects were evaluated by calculating the photoisomerization path of a modified chromophore, where the ring double bond has been saturated. Spectroscopic properties were calculated and compared with the available experimental data

  20. Anatomy of the magnetic catalysis by renormalization-group method

    Directory of Open Access Journals (Sweden)

    Koichi Hattori

    2017-12-01

    Full Text Available We first examine the scaling argument for a renormalization-group (RG analysis applied to a system subject to the dimensional reduction in strong magnetic fields, and discuss the fact that a four-Fermi operator of the low-energy excitations is marginal irrespective of the strength of the coupling constant in underlying theories. We then construct a scale-dependent effective four-Fermi interaction as a result of screened photon exchanges at weak coupling, and establish the RG method appropriately including the screening effect, in which the RG evolution from ultraviolet to infrared scales is separated into two stages by the screening-mass scale. Based on a precise agreement between the dynamical mass gaps obtained from the solutions of the RG and Schwinger–Dyson equations, we discuss an equivalence between these two approaches. Focusing on QED and Nambu–Jona-Lasinio model, we clarify how the properties of the interactions manifest themselves in the mass gap, and point out an importance of respecting the intrinsic energy-scale dependences in underlying theories for the determination of the mass gap. These studies are expected to be useful for a diagnosis of the magnetic catalysis in QCD.

  1. The Applications of Morphology Controlled ZnO in Catalysis

    Directory of Open Access Journals (Sweden)

    Yuhai Sun

    2016-11-01

    Full Text Available Zinc oxide (ZnO, with the unique chemical and physical properties of high chemical stability, broad radiation absorption range, high electrochemical coupling coefficient, and high photo-stability, is an attractive multifunctional material which has promoted great interest in many fields. What is more, its properties can be tuned by controllable synthesized morphologies. Therefore, after the success of the abundant morphology controllable synthesis, both the morphology-dependent ZnO properties and their related applications have been extensively investigated. This review concentrates on the properties of morphology-dependent ZnO and their applications in catalysis, mainly involved reactions on green energy and environmental issues, such as CO2 hydrogenation to fuels, methanol steam reforming to generate H2, bio-diesel production, pollutant photo-degradation, etc. The impressive catalytic properties of ZnO are associated with morphology tuned specific microstructures, defects or abilities of electron transportation, etc. The main morphology-dependent promotion mechanisms are discussed and summarized.

  2. Studies of Metal-Metal Bonded Compounds in Catalysis

    Energy Technology Data Exchange (ETDEWEB)

    Berry, John F. [Univ. of Wisconsin, Madison, WI (United States)

    2018-01-19

    The overall goals of this research are (1) to define the fundamental coordination chemistry underlying successful catalytic transformations promoted by metal-metal bonded compounds, and (2) to explore new chemical transformations that occur at metal-metal bonded sites that could lead to the discovery of new catalytic processes. Transformations of interest include metal-promoted reactions of carbene, nitrene, or nitrido species to yield products with new C–C and C–N bonds, respectively. The most promising suite of transition metal catalysts for these transformations is the set of metal-metal bonded coordination compounds of Ru and Rh of the general formula M2(ligand)4, where M = Ru or Rh and ligand = a monoanionic, bridging ligand such as acetate. Development of new catalysts and improvement of catalytic conditions have been stymied by a general lack of knowledge about the nature of highly reactive intermediates in these reactions, the knowledge that is to be supplied by this work. Our three specific objectives for this year have been (A) to trap, isolate, and characterize new reactive intermediates of general relevance to catalysis, (B) to explore the electronic structure and reactivity of these unusual species, and how these two properties are interrelated, and (C) to use our obtained mechanistic knowledge to design new catalysts with a focus on Earth-abundant first-row transition metal compounds.

  3. Catalysis as an Enabling Science for Sustainable Polymers.

    Science.gov (United States)

    Zhang, Xiangyi; Fevre, Mareva; Jones, Gavin O; Waymouth, Robert M

    2018-01-24

    The replacement of current petroleum-based plastics with sustainable alternatives is a crucial but formidable challenge for the modern society. Catalysis presents an enabling tool to facilitate the development of sustainable polymers. This review provides a system-level analysis of sustainable polymers and outlines key criteria with respect to the feedstocks the polymers are derived from, the manner in which the polymers are generated, and the end-of-use options. Specifically, we define sustainable polymers as a class of materials that are derived from renewable feedstocks and exhibit closed-loop life cycles. Among potential candidates, aliphatic polyesters and polycarbonates are promising materials due to their renewable resources and excellent biodegradability. The development of renewable monomers, the versatile synthetic routes to convert these monomers to polyesters and polycarbonate, and the different end-of-use options for these polymers are critically reviewed, with a focus on recent advances in catalytic transformations that lower the technological barriers for developing more sustainable replacements for petroleum-based plastics.

  4. Sequential rhodium/palladium catalysis: enantioselective formation of dihydroquinolinones in the presence of achiral and chiral ligands.

    Science.gov (United States)

    Zhang, Lei; Qureshi, Zafar; Sonaglia, Lorenzo; Lautens, Mark

    2014-12-08

    Compatible combinations of achiral and chiral ligands can be used in rhodium/palladium catalysis to achieve highly enantioselective domino reactions. The difference in rates of catalysis and minimal effects of ligand interference confer control in the domino sequence. The "all-in-one" 1,4-conjugate arylation and C-N cross-coupling through sequential Rh/Pd catalysis provides access to enantioenriched dihydroquinolinone building blocks. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Interannual variability of the Equatorial Jets in the Indian Ocean from the merged altimetry data

    Digital Repository Service at National Institute of Oceanography (India)

    Somayajulu, Y.K.; Murty, V.S.N.; Neelima, C.; Jagadeesh, P.S.V.

    The merged ERS-1/2, TOPEX/Poseidon and Jason-1 altimeter weekly sea level anomalies (SLAs) for the period 1997- 2005 were analyzed to study the variability of sea level and computed geostrophic currents in relation to the equatorial jets...

  6. Key Variables of Merging Behaviour : Empirical Comparison between Two Sites and Assessment of Gap Acceptance Theory

    NARCIS (Netherlands)

    Marczak, F.; Daamen, W.; Buisson, C.

    2013-01-01

    This paper presents two empirical trajectory data sets focusing on the merging behaviour on a motorway, both in the Netherlands and in France. A careful review of the literature shows that the main theories explaining this behaviour rely on the hypothesis of gap acceptance, i.e. the fact that each

  7. Merging Micro and Macro Intervention: Social Work Practice with Groups in the Community

    Science.gov (United States)

    Knight, Carolyn; Gitterman, Alex

    2018-01-01

    Clinical or micro intervention predominates in social work education and practice. The prevailing assumption in social work practice and education is that one engages in either micro or macro intervention. In this article, we describe how these interventions may be merged into an integrated whole through social work practice with groups. The…

  8. The European Large-Area ISO Survey (ELAIS): the final band-merged catalogue

    DEFF Research Database (Denmark)

    Rowan-Robinson, M.; Lari, C.; Perez-Fournon, I.

    2004-01-01

    We present the final band-merged European Large-Area ISO Survey (ELAIS) Catalogue at 6.7, 15, 90 and 175 mum, and the associated data at U, g', r', i', Z, J, H, K and 20 cm. The origin of the survey, infrared and radio observations, data-reduction and optical identifications are briefly reviewed...

  9. Drivers' Visual Characteristics when Merging onto or Exiting an Urban Expressway.

    Directory of Open Access Journals (Sweden)

    Ying Cheng

    Full Text Available The aim of this study is to examine drivers' visual and driving behavior while merging onto or exiting an urban expressway with low and high traffic densities. The analysis was conducted according to three periods (approaching, merging or exiting, and accelerating or decelerating. A total of 10 subjects (8 males and 2 females with ages ranging from 25 to 52 years old (M = 30.0 years old participated in the study. The research was conducted in a natural driving situation, and the drivers' eye movements were monitored and recorded using an eye tracking system. The results show that the influence of traffic density on the glance duration and scan duration is more significant when merging than when exiting. The results also demonstrate that the number of glances and the mean glance duration are mainly related to the driving task (e.g., the merging period. Therefore, drivers' visual search strategies mainly depend on the current driving task. With regard to driving behavior, the variation tendencies of the duration and the velocity of each period are similar. These results support building an automated driving assistant system that can automatically identify gaps and accelerate or decelerate the car accordingly or provide suggestions to the driver to do so.

  10. Mining MaNGA for Merging Galaxies: A New Imaging and Kinematic Technique from Hydrodynamical Simulations

    Science.gov (United States)

    Nevin, Becky; Comerford, Julia M.; Blecha, Laura

    2018-06-01

    Merging galaxies play a key role in galaxy evolution, and progress in our understanding of galaxy evolution is slowed by the difficulty of making accurate galaxy merger identifications. Mergers are typically identified using imaging alone, which has its limitations and biases. With the growing popularity of integral field spectroscopy (IFS), it is now possible to use kinematic signatures to improve galaxy merger identifications. I use GADGET-3 hydrodynamical simulations of merging galaxies with the radiative transfer code SUNRISE, the later of which enables me to apply the same analysis to simulations and observations. From the simulated galaxies, I have developed the first merging galaxy classification scheme that is based on kinematics and imaging. Utilizing a Linear Discriminant Analysis tool, I have determined which kinematic and imaging predictors are most useful for identifying mergers of various merger parameters (such as orientation, mass ratio, gas fraction, and merger stage). I will discuss the strengths and limitations of the classification technique and then my initial results for applying the classification to the >10,000 observed galaxies in the MaNGA (Mapping Nearby Galaxies at Apache Point) IFS survey. Through accurate identification of merging galaxies in the MaNGA survey, I will advance our understanding of supermassive black hole growth in galaxy mergers and other open questions related to galaxy evolution.

  11. Electron capture in slow collisions of multicharged ions with hydrogen atoms using merged beams

    International Nuclear Information System (INIS)

    Havener, C.C.; Nesnidal, M.P.; Porter, M.R.; Phaneuf, R.A.

    1991-01-01

    Absolute total electron-capture cross-section mesurements are reported for collisions of O 3+ and O 4+ with atomic hydrogen in the energy range 1-1000 eV /amu using merged beams. The data are compared with available coupled-states theoretical calculations. (orig.)

  12. Merging Library and Computing Services at Kenyon College: A Progress Report.

    Science.gov (United States)

    Oden, Robert A., Jr.; Temple, Daniel B.; Cottrell, Janet R.; Griggs, Ronald K.; Turney, Glen W.; Wojcik, Frank M.

    2001-01-01

    Describes the evolution and progress toward a uniquely integrated library and computer services unit at Kenyon College. Discusses its focus on constituencies; merging of the divisions; benefits for students, faculty, administrative units, and the institution; meeting challenges; and generalizing from the model. (EV)

  13. The challenge of merging : Merger patterns, premerger status, and merger support

    NARCIS (Netherlands)

    Giessner, [No Value; Täuber, Susanne; Viki, GT; Otten, S; Terry, DJ; Giessner, S.R

    Employees of merging organizations often show resistance to the merger. The employees' support depends on the companies' premerger status and on the merger pattern. Based on an inter-group perspective, three studies were conducted to investigate the influence of premerger status (high, low) and

  14. Particle acceleration during merging-compression plasma start-up in the Mega Amp Spherical Tokamak

    Science.gov (United States)

    McClements, K. G.; Allen, J. O.; Chapman, S. C.; Dendy, R. O.; Irvine, S. W. A.; Marshall, O.; Robb, D.; Turnyanskiy, M.; Vann, R. G. L.

    2018-02-01

    Magnetic reconnection occurred during merging-compression plasma start-up in the Mega Amp Spherical Tokamak (MAST), resulting in the prompt acceleration of substantial numbers of ions and electrons to highly suprathermal energies. Accelerated field-aligned ions (deuterons and protons) were detected using a neutral particle analyser at energies up to about 20 keV during merging in early MAST pulses, while nonthermal electrons have been detected indirectly in more recent pulses through microwave bursts. However no increase in soft x-ray emission was observed until later in the merging phase, by which time strong electron heating had been detected through Thomson scattering measurements. A test-particle code CUEBIT is used to model ion acceleration in the presence of an inductive toroidal electric field with a prescribed spatial profile and temporal evolution based on Hall-MHD simulations of the merging process. The simulations yield particle distributions with properties similar to those observed experimentally, including strong field alignment of the fast ions and the acceleration of protons to higher energies than deuterons. Particle-in-cell modelling of a plasma containing a dilute field-aligned suprathermal electron component suggests that at least some of the microwave bursts can be attributed to the anomalous Doppler instability driven by anisotropic fast electrons, which do not produce measurable enhancements in soft x-ray emission either because they are insufficiently energetic or because the nonthermal bremsstrahlung emissivity during this phase of the pulse is below the detection threshold. There is no evidence of runaway electron acceleration during merging, possibly due to the presence of three-dimensional field perturbations.

  15. ENHANCED OFF-CENTER STELLAR TIDAL DISRUPTIONS BY SUPERMASSIVE BLACK HOLES IN MERGING GALAXIES

    International Nuclear Information System (INIS)

    Liu, F. K.; Chen, Xian

    2013-01-01

    Off-center stellar tidal disruption flares have been suggested to be a powerful probe of recoiling supermassive black holes (SMBHs) out of galactic centers due to anisotropic gravitational wave radiations. However, off-center tidal flares can also be produced by SMBHs in merging galaxies. In this paper, we computed the tidal flare rates by dual SMBHs in two merging galaxies before the SMBHs become self-gravitationally bounded. We employ an analytical model to calculate the tidal loss-cone feeding rates for both SMBHs, taking into account two-body relaxation of stars, tidal perturbations by the companion galaxy, and chaotic stellar orbits in triaxial gravitational potential. We show that for typical SMBHs with masses 10 7 M ☉ , the loss-cone feeding rates are enhanced by mergers up to Γ ∼ 10 –2 yr –1 , about two orders of magnitude higher than those by single SMBHs in isolated galaxies and about four orders of magnitude higher than those by recoiling SMBHs. The enhancements are mainly due to tidal perturbations by the companion galaxy. We suggest that off-center tidal flares are overwhelmed by those from merging galaxies, making the identification of recoiling SMBHs challenging. Based on the calculated rates, we estimate the relative contributions of tidal flare events by single, binary, and dual SMBH systems during cosmic time. Our calculations show that the off-center tidal disruption flares by un-bound SMBHs in merging galaxies contribute a fraction comparable to that by single SMBHs in isolated galaxies. We conclude that off-center tidal disruptions are powerful tracers of the merging history of galaxies and SMBHs.

  16. Observations and Simulations of Formation of Broad Plasma Depletions Through Merging Process

    Science.gov (United States)

    Huang, Chao-Song; Retterer, J. M.; Beaujardiere, O. De La; Roddy, P. A.; Hunton, D.E.; Ballenthin, J. O.; Pfaff, Robert F.

    2012-01-01

    Broad plasma depletions in the equatorial ionosphere near dawn are region in which the plasma density is reduced by 1-3 orders of magnitude over thousands of kilometers in longitude. This phenomenon is observed repeatedly by the Communication/Navigation Outage Forecasting System (C/NOFS) satellite during deep solar minimum. The plasma flow inside the depletion region can be strongly upward. The possible causal mechanism for the formation of broad plasma depletions is that the broad depletions result from merging of multiple equatorial plasma bubbles. The purpose of this study is to demonstrate the feasibility of the merging mechanism with new observations and simulations. We present C/NOFS observations for two cases. A series of plasma bubbles is first detected by C/NOFS over a longitudinal range of 3300-3800 km around midnight. Each of the individual bubbles has a typical width of approx 100 km in longitude, and the upward ion drift velocity inside the bubbles is 200-400 m/s. The plasma bubbles rotate with the Earth to the dawn sector and become broad plasma depletions. The observations clearly show the evolution from multiple plasma bubbles to broad depletions. Large upward plasma flow occurs inside the depletion region over 3800 km in longitude and exists for approx 5 h. We also present the numerical simulations of bubble merging with the physics-based low-latitude ionospheric model. It is found that two separate plasma bubbles join together and form a single, wider bubble. The simulations show that the merging process of plasma bubbles can indeed occur in incompressible ionospheric plasma. The simulation results support the merging mechanism for the formation of broad plasma depletions.

  17. Mining CANDELS for Tidal Features to Constrain Major Merging During Cosmic Noon

    Science.gov (United States)

    McIntosh, Daniel H.; Mantha, Kameswara; Ciaschi, Cody; Evan, Rubyet A.; Fries, Logan B.; Landry, Luther; Thompson, Scott E.; Snyder, Gregory; Guo, Yicheng; Ceverino, Daniel; Häuβler, Boris; Primack, Joel; Simons, Raymond C.; Zheng, Xianzhong; Cosmic Assembly Near-Infrared Deep Extragalactic Legacy Survey (CANDELS) Team

    2018-01-01

    The role of major merging in the rapid buildup and development of massive galaxies at z>1 remains an open question. New theories and observations suggest that non-merging processes like violent disk instabilities may be more vital than previously thought at assembling bulges, producing clumps, and inducing morphological disturbances that may be misinterpreted as the product of major merging. We will present initial results on a systematic search for hallmark tidal indicators of major merging in a complete sample of nearly 6000 massive z>1 galaxies from CANDELS (Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey), the premiere HST/WFC3 Treasury program. We have visually inspected published GALFIT F160W residual (image-model) maps and produced a comprehensive new catalog of Sersic residual characteristics based on a variety of natural features and poor-fit artifacts. Using this catalog, we find the frequency of galaxies with tidal signatures is very small in CANDELS data. Accounting for the brief time scale associated with faint transient tidal features, our preliminary finding indicates that merger fractions derived from the CANDELS morphological classification efforts are substantially overestimated. We are using the database of residual classifications as a baseline to (1) produce improved multi-component residual maps using GALFIT_M, (2) automatically extract and quantify plausible tidal indicators and substructures (clumps vs. multiple nuclei), (3) develop a new deep-learning classification pipeline to robustly identify merger indicators in imaging data, and (4) inform the systematic analyses of synthetic mock (CANDELized) images from zoom-in hydrodynamic simulations to thoroughly quantify the impacts of cosmological dimming, and calibrate the observability timescale of tidal feature detections. Our study will ultimately yield novel constraints on merger rates at z>1 and a definitive census of massive high-noon galaxies with tidal and double

  18. Investigating the incidence of youth mental health problem by merging person register and school level class room survey data

    Directory of Open Access Journals (Sweden)

    Marko Merikukka

    2017-04-01

    It is possible to merge datasets from school level to an individual level register data. The merged big data offers new possibilities to study questions related to the prevalence of mental health problems. The new linked data can be further analyzed to hierarchical model.

  19. Electrostatic catalysis of a Diels-Alder reaction

    Science.gov (United States)

    Aragonès, Albert C.; Haworth, Naomi L.; Darwish, Nadim; Ciampi, Simone; Bloomfield, Nathaniel J.; Wallace, Gordon G.; Diez-Perez, Ismael; Coote, Michelle L.

    2016-03-01

    It is often thought that the ability to control reaction rates with an applied electrical potential gradient is unique to redox systems. However, recent theoretical studies suggest that oriented electric fields could affect the outcomes of a range of chemical reactions, regardless of whether a redox system is involved. This possibility arises because many formally covalent species can be stabilized via minor charge-separated resonance contributors. When an applied electric field is aligned in such a way as to electrostatically stabilize one of these minor forms, the degree of resonance increases, resulting in the overall stabilization of the molecule or transition state. This means that it should be possible to manipulate the kinetics and thermodynamics of non-redox processes using an external electric field, as long as the orientation of the approaching reactants with respect to the field stimulus can be controlled. Here, we provide experimental evidence that the formation of carbon-carbon bonds is accelerated by an electric field. We have designed a surface model system to probe the Diels-Alder reaction, and coupled it with a scanning tunnelling microscopy break-junction approach. This technique, performed at the single-molecule level, is perfectly suited to deliver an electric-field stimulus across approaching reactants. We find a fivefold increase in the frequency of formation of single-molecule junctions, resulting from the reaction that occurs when the electric field is present and aligned so as to favour electron flow from the dienophile to the diene. Our results are qualitatively consistent with those predicted by quantum-chemical calculations in a theoretical model of this system, and herald a new approach to chemical catalysis.

  20. New Ir Bis-Carbonyl Precursor for Water Oxidation Catalysis

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Daria L. [Department of Chemistry, Yale University, 225; Beltrán-Suito, Rodrigo [Department of Chemistry, Yale University, 225; Thomsen, Julianne M. [Department of Chemistry, Yale University, 225; Hashmi, Sara M. [Department of Chemical and Environmental; Materna, Kelly L. [Department of Chemistry, Yale University, 225; Sheehan, Stafford W. [Catalytic Innovations LLC, 70 Crandall; Mercado, Brandon Q. [Department of Chemistry, Yale University, 225; Brudvig, Gary W. [Department of Chemistry, Yale University, 225; Crabtree, Robert H. [Department of Chemistry, Yale University, 225

    2016-02-05

    This paper introduces IrI(CO)2(pyalc) (pyalc = (2-pyridyl)-2-propanoate) as an atom-efficient precursor for Ir-based homogeneous oxidation catalysis. This compound was chosen to simplify analysis of the water oxidation catalyst species formed by the previously reported Cp*IrIII(pyalc)OH water oxidation precatalyst. Here, we present a comparative study on the chemical and catalytic properties of these two precursors. Previous studies show that oxidative activation of Cp*Ir-based precursors with NaIO4 results in formation of a blue IrIV species. This activation is concomitant with the loss of the placeholder Cp* ligand which oxidatively degrades to form acetic acid, iodate, and other obligatory byproducts. The activation process requires substantial amounts of primary oxidant, and the degradation products complicate analysis of the resulting IrIV species. The species formed from oxidation of the Ir(CO)2(pyalc) precursor, on the other hand, lacks these degradation products (the CO ligands are easily lost upon oxidation) which allows for more detailed examination of the resulting Ir(pyalc) active species both catalytically and spectroscopically, although complete structural analysis is still elusive. Once Ir(CO)2(pyalc) is activated, the system requires acetic acid or acetate to prevent the formation of nanoparticles. Investigation of the activated bis-carbonyl complex also suggests several Ir(pyalc) isomers may exist in solution. By 1H NMR, activated Ir(CO)2(pyalc) has fewer isomers than activated Cp*Ir complexes, allowing for advanced characterization. Future research in this direction is expected to contribute to a better structural understanding of the active species. A diol crystallization agent was needed for the structure determination of 3.

  1. Horse Liver Alcohol Dehydrogenase: Zinc Coordination and Catalysis

    Energy Technology Data Exchange (ETDEWEB)

    Plapp, Bryce V.; Savarimuthu, Baskar Raj; Ferraro, Daniel J.; Rubach, Jon K.; Brown, Eric N.; Ramaswamy, S. (Iowa)

    2017-07-07

    During catalysis by liver alcohol dehydrogenase (ADH), a water bound to the catalytic zinc is replaced by the oxygen of the substrates. The mechanism might involve a pentacoordinated zinc or a double-displacement reaction with participation by a nearby glutamate residue, as suggested by studies of human ADH3, yeast ADH1, and some other tetrameric ADHs. Zinc coordination and participation of water in the enzyme mechanism were investigated by X-ray crystallography. The apoenzyme and its complex with adenosine 5'-diphosphoribose have an open protein conformation with the catalytic zinc in one position, tetracoordinated by Cys-46, His-67, Cys-174, and a water molecule. The bidentate chelators 2,2'-bipyridine and 1,10-phenanthroline displace the water and form a pentacoordinated zinc. The enzyme–NADH complex has a closed conformation similar to that of ternary complexes with coenzyme and substrate analogues; the coordination of the catalytic zinc is similar to that found in the apoenzyme, except that a minor, alternative position for the catalytic zinc is ~1.3 Å from the major position and closer to Glu-68, which could form the alternative coordination to the catalytic zinc. Complexes with NADH and N-1-methylhexylformamide or N-benzylformamide (or with NAD+ and fluoro alcohols) have the classical tetracoordinated zinc, and no water is bound to the zinc or the nicotinamide rings. The major forms of the enzyme in the mechanism have a tetracoordinated zinc, where the carboxylate group of Glu-68 could participate in the exchange of water and substrates on the zinc. Hydride transfer in the Michaelis complexes does not involve a nearby water.

  2. Highly conserved small subunit residues influence rubisco large subunit catalysis.

    Science.gov (United States)

    Genkov, Todor; Spreitzer, Robert J

    2009-10-30

    The chloroplast enzyme ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) catalyzes the rate-limiting step of photosynthetic CO(2) fixation. With a deeper understanding of its structure-function relationships and competitive inhibition by O(2), it may be possible to engineer an increase in agricultural productivity and renewable energy. The chloroplast-encoded large subunits form the active site, but the nuclear-encoded small subunits can also influence catalytic efficiency and CO(2)/O(2) specificity. To further define the role of the small subunit in Rubisco function, the 10 most conserved residues in all small subunits were substituted with alanine by transformation of a Chlamydomonas reinhardtii mutant that lacks the small subunit gene family. All the mutant strains were able to grow photosynthetically, indicating that none of the residues is essential for function. Three of the substitutions have little or no effect (S16A, P19A, and E92A), one primarily affects holoenzyme stability (L18A), and the remainder affect catalysis with or without some level of associated structural instability (Y32A, E43A, W73A, L78A, P79A, and F81A). Y32A and E43A cause decreases in CO(2)/O(2) specificity. Based on the x-ray crystal structure of Chlamydomonas Rubisco, all but one (Glu-92) of the conserved residues are in contact with large subunits and cluster near the amino- or carboxyl-terminal ends of large subunit alpha-helix 8, which is a structural element of the alpha/beta-barrel active site. Small subunit residues Glu-43 and Trp-73 identify a possible structural connection between active site alpha-helix 8 and the highly variable small subunit loop between beta-strands A and B, which can also influence Rubisco CO(2)/O(2) specificity.

  3. Solar photo-catalysis to remove paper mill wastewater pollutants

    Energy Technology Data Exchange (ETDEWEB)

    Amat, A.M.; Arques, A. [Departamento de Ingenieria Textil y Papelera, Universidad Politecnica de Valencia, EPSA-UPV, Paseo del Viaducto 1, E-03801 Alcoy (Spain); Lopez, F. [Departamento de Ingenieria Quimica y Nuclear, Universidad Politecnica de Valencia, EPSA-UPV, Paseo del Viaducto 1, E-03801 Alcoy (Spain); Miranda, M.A. [Departamento de Quimica, Instituto de Tecnologia Quimica, Universidad Politecnica de Valencia, UPV-CSIC, 46071 Valencia (Spain)

    2005-10-01

    Solar degradation of effluents in board paper industries has been studied using different photo-catalysts: Fenton reagent and TiO{sub 2}. p-Toluenesulfonic acid was chosen as a model compound for sulfonated pollutants already present in the incoming waters. The abatement of a 0.005M solution of this pollutant after 6h was found to be 47% for photo-Fenton and 27% for TiO{sub 2} (pseudo-first-order rate constants 0.002 and 0.001min{sup -1}, respectively). Eugenol and guaiacol were chosen as models for lignin degradation products. They were efficiently degraded by both photo-catalysts, and reaction rates were higher for eugenol (0.0024min{sup -1}) than for guaiacol (0.0018min{sup -1}). A solution of sodium acetate, sodium butyrate and d-glucose was chosen to study the effect of photo-catalysis towards volatile fatty acids and saccharides arising from starch degradation. In this case a clearly worse performance was observed: only 20% degradation was observed after 7h of treatment. When the real wastewater was treated with photo-catalytic methods, the best performance was obtained in closed circuits, when the COD values were higher. This fact can be explained by taking into account that closure of the circuits results in an accumulation of reluctant phenolic pollutants, while starch derivatives are continuously degraded by microorganisms in the circuits; as phenolic compounds are more easily degraded by photo-catalytic means, these methods are suitable for closed circuits. Finally, changes in the BOD{sub st} were determined by means of active sludges respirometry. A noticeable BOD{sub st} increase (30-50%) was observed in all cases, attributable to chemical oxidation of biodegradable species. (author)

  4. Core-shell nanoreactors for efficient aqueous biphasic catalysis.

    Science.gov (United States)

    Zhang, Xuewei; Cardozo, Andrés F; Chen, Si; Zhang, Wenjing; Julcour, Carine; Lansalot, Muriel; Blanco, Jean-François; Gayet, Florence; Delmas, Henri; Charleux, Bernadette; Manoury, Eric; D'Agosto, Franck; Poli, Rinaldo

    2014-11-17

    Water-borne phosphine-functionalized core-cross-linked micelles (CCM) consisting of a hydrophobic core and a hydrophilic shell were obtained as stable latexes by reversible addition-fragmentation chain transfer (RAFT) in water in a one-pot, three-step process. Initial homogeneous aqueous-phase copolymerization of methacrylic acid (MAA) and poly(ethylene oxide) methyl ether methacrylate (PEOMA) is followed by copolymerization of styrene (S) and 4-diphenylphosphinostyrene (DPPS), yielding P(MAA-co-PEOMA)-b-P(S-co-DPPS) amphiphilic block copolymer micelles (M) by polymerization-induced self-assembly (PISA), and final micellar cross-linking with a mixture of S and diethylene glycol dimethacrylate. The CCM were characterized by dynamic light scattering and NMR spectroscopy to evaluate size, dispersity, stability, and the swelling ability of various organic substrates. Coordination of [Rh(acac)(CO)2 ] (acac=acetylacetonate) to the core-confined phosphine groups was rapid and quantitative. The CCM and M latexes were then used, in combination with [Rh(acac)(CO)2 ], to catalyze the aqueous biphasic hydroformylation of 1-octene, in which they showed high activity, recyclability, protection of the activated Rh center by the polymer scaffold, and low Rh leaching. The CCM latex gave slightly lower catalytic activity but significantly less Rh leaching than the M latex. A control experiment conducted in the presence of the sulfoxantphos ligand pointed to the action of the CCM as catalytic nanoreactors with substrate and product transport into and out of the polymer core, rather than as a surfactant in interfacial catalysis. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. On the merging rates of envelope-deprived components of binary systems which can give rise to supernova events

    Science.gov (United States)

    Tornambe, Amedeo

    1989-08-01

    Theoretical rates of mergings of envelope-deprived components of binary systems, which can give rise to supernova events are described. The effects of the various assumptions on the physical properties of the progenitor system and of its evolutionary behavior through common envelope phases are discussed. Four cases have been analyzed: CO-CO, He-CO, He-He double degenerate mergings and He star-CO dwarf merging. It is found that, above a critical efficiency of the common envelope action in system shrinkage, the rate of CO-CO mergings is not strongly sensitive to the efficiency. Below this critical value, no CO-CO systems will survive for times larger than a few Gyr. In contrast, He-CO dwarf systems will continue to merge at a reasonable rate up to 20 Gyr, and more, also under extreme conditions.

  6. Cu and Cu-Based Nanoparticles: Synthesis and Applications in Catalysis.

    Science.gov (United States)

    Gawande, Manoj B; Goswami, Anandarup; Felpin, François-Xavier; Asefa, Tewodros; Huang, Xiaoxi; Silva, Rafael; Zou, Xiaoxin; Zboril, Radek; Varma, Rajender S

    2016-03-23

    The applications of copper (Cu) and Cu-based nanoparticles, which are based on the earth-abundant and inexpensive copper metal, have generated a great deal of interest in recent years, especially in the field of catalysis. The possible modification of the chemical and physical properties of these nanoparticles using different synthetic strategies and conditions and/or via postsynthetic chemical treatments has been largely responsible for the rapid growth of interest in these nanomaterials and their applications in catalysis. In addition, the design and development of novel support and/or multimetallic systems (e.g., alloys, etc.) has also made significant contributions to the field. In this comprehensive review, we report different synthetic approaches to Cu and Cu-based nanoparticles (metallic copper, copper oxides, and hybrid copper nanostructures) and copper nanoparticles immobilized into or supported on various support materials (SiO2, magnetic support materials, etc.), along with their applications in catalysis. The synthesis part discusses numerous preparative protocols for Cu and Cu-based nanoparticles, whereas the application sections describe their utility as catalysts, including electrocatalysis, photocatalysis, and gas-phase catalysis. We believe this critical appraisal will provide necessary background information to further advance the applications of Cu-based nanostructured materials in catalysis.

  7. High resolution radar-rain gauge data merging for urban hydrology: current practice and beyond

    Science.gov (United States)

    Ochoa Rodriguez, Susana; Wang, Li-Pen; Bailey, Andy; Willems, Patrick; Onof, Christian

    2017-04-01

    In this work a thorough test is conducted of radar-rain gauge merging techniques at urban scales, under different climatological conditions and rain gauge density scenarios. The aim is to provide guidance regarding the suitability and application of merging methods at urban scales, which is lacking at present. The test is conducted based upon two pilot locations, i.e. the cities of Edinburgh (254 km^2) and Birmingham (431 km^2), for which a total of 96 and 84 tipping bucket rain gauges were respectively available, alongside radar QPEs, dense runoff records and urban drainage models. Three merging techniques, namely Mean Field Bias (MFB) adjustment, kriging with external (KED) and Bayesian (BAY) combination, were selected for testing on grounds of performance and common use. They were initially tested as they were originally formulated and as they are reportedly commonly applied using typically available radar and rain gauge data. Afterwards, they were tested in combination with two special treatments which were identified as having the potential to improve merging applicability for urban hydrology: (1) reduction of temporal sampling errors in radar QPEs through temporal interpolation and (2) singularity-based decomposition of radar QPEs prior to merging. These treatments ultimately aim at improving the consistency between radar and rain gauge records, which has been identified as the chief factor affecting merging performance and is particularly challenging at the fine spatial-temporal resolutions required for urban applications. The main findings of this study are the following: - All merging methods were found to improve the applicability of radar QPEs for urban hydrological applications, but the degree of improvement they provide and the added value of radar information vary for each merging method and are also a function of climatological conditions and rain gauge density scenarios. - Overall, KED displayed the best performance, with BAY being a close second

  8. Towards an atomic level understanding of niobia based catalysts and catalysis by combining the science of catalysis with surface science

    Directory of Open Access Journals (Sweden)

    Martin Schmal

    2009-06-01

    Full Text Available The science of catalysis and surface science have developed, independently, key information for understanding catalytic processes. One might argue: is there anything fundamental to be discovered through the interplay between catalysis and surface science? Real catalysts of monometallic and bimetallic Co/Nb2O5 and Pd-Co/Nb2O5 catalysts showed interesting selectivity results on the Fischer-Tropsch synthesis (Noronha et al. 1996, Rosenir et al. 1993. The presence of a noble metal increased the C+5 selectivity and decreased the methane formation depending of the reduction temperature. Model catalyst of Co-Pd supported on niobia and alumina were prepared and characterized at the atomic level, thus forming the basis for a comparison with "real" support materials. Growth, morphology and structure of both pure metal and alloy particles were studied. It is possible to support the strong metal support interaction suggested by studies on real catalysts via the investigation of model systems for niobia in comparison to alumina support in which this effect does not occur. Formation of Co2+ penetration into the niobia lattice was suggested on the basis of powder studies and can be fully supported on the basis of model studies. It is shown for both real catalysts and model systems that oxidation state of Co plays a key role in controlling the reactivity in Fischer-Tropsch reactions systems and that the addition of Pd is a determining factor for the stability of the catalyst. It is demonstrated that the interaction with unsaturated hydrocarbons depends strongly on the state of oxidation.As ciências da catálise e da superfície têm desenvolvido independentemente temas básicos para o entendimento de processos catalíticos. Pode-se até questionar se há ainda algo fundamental para ser descoberto através da interface entre catálise eciência da superfície? Catalisadores mono e bimetálicos de Co/Nb2O5 e Pd-Co/ Nb2O5 apresentaram resultados interessantes de

  9. Extremely efficient catalysis of carbon-carbon bond formation using "click" dendrimer-stabilized palladium nanoparticles.

    Science.gov (United States)

    Astruc, Didier; Ornelas, Cátia; Diallo, Abdou K; Ruiz, Jaime

    2010-07-20

    This article is an account of the work carried out in the authors' laboratory illustrating the usefulness of dendrimer design for nanoparticle palladium catalysis. The "click" synthesis of dendrimers constructed generation by generation by 1-->3 C connectivity, introduces 1,2,3-triazolyl ligands insides the dendrimers at each generation. Complexation of the ligands by Pd(II) followed by reduction to Pd(0) forms dendrimer-stabilized Pd nanoparticles (PdNPs) that are extremely reactive in the catalysis of olefin hydrogenation and C-C bond coupling reactions. The stabilization can be outer-dendritic for the small zeroth-generation dendrimer or intra-dendritic for the larger first- and second-generation dendrimers. The example of the Miyaura-Suzuki reaction that can be catalyzed by down to 1 ppm of PdNPs with a "homeopathic" mechanism (the less, the better) is illustrated here, including catalysis in aqueous solvents.

  10. Morphology-controlled synthesis of silver nanostructures via a seed catalysis process

    Science.gov (United States)

    Chen, Chang; Wang, Li; Yu, Haojie; Wang, Jianjun; Zhou, Junfeng; Tan, Qiaohua; Deng, Libo

    2007-03-01

    A novel, effective strategy named 'seed catalysis' has been described here to synthesize silver nanostructures with controllable morphology. Typically, we added Na2S into the reaction system and the Ag2S semiconductor colloids formed at the initial stage would act as both seeds and catalyst in the silver reduction. The morphology of products is controlled by the concentration of Na2S added to the system. Low concentration of Na2S gives nanocubes of 40-50 nm in size, while a high concentration of Na2S is of benefit to obtain nanowires. The growth of the silver crystal is also accelerated by the catalysis of Ag2S. Electron microscopy and UV-vis absorption spectra have been used to investigate the evolution of silver nanowires, and a reasonable mechanism to explain the role of Ag2S seeds has also been suggested. This semiconductor seed catalysis strategy will provide wide applications in the fabrication of metal nanomaterials.

  11. A new class of PN3-pincer ligands for metal–ligand cooperative catalysis

    KAUST Repository

    Li, Huaifeng

    2014-12-01

    Work on a new class of PN3-pincer ligands for metal-ligand cooperative catalysis is reviewed. While the field of the pyridine-based PN3-transition metal pincer complexes is still relatively young, many important applications of these complexes have already emerged. In several cases, the PN3-pincer complexes for metal-ligand cooperative catalysis result in significantly improved or unprecedented activities. The synthesis and coordination chemistry of PN3-pincer ligands are briefly summarized first to cover the synthetic routes for their preparation, followed by a focus review on their applications in catalysis. A specific emphasis is placed on the later section about the role of PN3-pincer ligands\\' dearomatization-rearomatization steps during the catalytic cycles. The mechanistic insights from density functional theory (DFT) calculations are also discussed.

  12. Morphology-controlled synthesis of silver nanostructures via a seed catalysis process

    International Nuclear Information System (INIS)

    Chen Chang; Wang Li; Yu Haojie; Wang Jianjun; Zhou Junfeng; Tan Qiaohua; Deng Libo

    2007-01-01

    A novel, effective strategy named 'seed catalysis' has been described here to synthesize silver nanostructures with controllable morphology. Typically, we added Na 2 S into the reaction system and the Ag 2 S semiconductor colloids formed at the initial stage would act as both seeds and catalyst in the silver reduction. The morphology of products is controlled by the concentration of Na 2 S added to the system. Low concentration of Na 2 S gives nanocubes of 40-50 nm in size, while a high concentration of Na 2 S is of benefit to obtain nanowires. The growth of the silver crystal is also accelerated by the catalysis of Ag 2 S. Electron microscopy and UV-vis absorption spectra have been used to investigate the evolution of silver nanowires, and a reasonable mechanism to explain the role of Ag 2 S seeds has also been suggested. This semiconductor seed catalysis strategy will provide wide applications in the fabrication of metal nanomaterials

  13. A new class of PN3-pincer ligands for metal–ligand cooperative catalysis

    KAUST Repository

    Li, Huaifeng; Zheng, Bin; Huang, Kuo-Wei

    2014-01-01

    Work on a new class of PN3-pincer ligands for metal-ligand cooperative catalysis is reviewed. While the field of the pyridine-based PN3-transition metal pincer complexes is still relatively young, many important applications of these complexes have already emerged. In several cases, the PN3-pincer complexes for metal-ligand cooperative catalysis result in significantly improved or unprecedented activities. The synthesis and coordination chemistry of PN3-pincer ligands are briefly summarized first to cover the synthetic routes for their preparation, followed by a focus review on their applications in catalysis. A specific emphasis is placed on the later section about the role of PN3-pincer ligands' dearomatization-rearomatization steps during the catalytic cycles. The mechanistic insights from density functional theory (DFT) calculations are also discussed.

  14. Converting Homogeneous to Heterogeneous in Electrophilic Catalysis using Monodisperse Metal Nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Witham, Cole A.; Huang, Wenyu; Tsung, Chia-Kuang; Kuhn, John N.; Somorjai, Gabor A.; Toste, F. Dean

    2009-10-15

    A continuing goal in catalysis is the transformation of processes from homogeneous to heterogeneous. To this end, nanoparticles represent a new frontier in heterogeneous catalysis, where this conversion is supplemented by the ability to obtain new or divergent reactivity and selectivity. We report a novel method for applying heterogeneous catalysts to known homogeneous catalytic reactions through the design and synthesis of electrophilic platinum nanoparticles. These nanoparticles are selectively oxidized by the hypervalent iodine species PhICl{sub 2}, and catalyze a range of {pi}-bond activation reactions previously only homogeneously catalyzed. Multiple experimental methods are utilized to unambiguously verify the heterogeneity of the catalytic process. The discovery of treatments for nanoparticles that induce the desired homogeneous catalytic activity should lead to the further development of reactions previously inaccessible in heterogeneous catalysis. Furthermore, our size and capping agent study revealed that Pt PAMAM dendrimer-capped nanoparticles demonstrate superior activity and recyclability compared to larger, polymer-capped analogues.

  15. 2010 CATALYSIS GORDON RESEARCH CONFERENCE, JUNE 27 - JULY 2, 2010, NEW LONDON, NEW HAMPSHIRE

    Energy Technology Data Exchange (ETDEWEB)

    Abhaya Datye

    2010-07-02

    Catalysis is a key technology for improving the quality of life while simultaneously reducing the adverse impact of human activities on the environment. The discovery of new catalytic processes and the improvement of existing ones are also critically important for securing the nation's energy supply. The GRC on Catalysis is considered one the most prestigious conference for catalysis research, bringing together leading researchers from both academia, industry and national labs to discuss the latest, most exciting research in catalysis and the future directions for the field. The 2010 GRC on Catalysis will follow time-honored traditions and feature invited talks from the world's leading experts in the fundamentals and applications of catalytic science and technology. We plan to have increased participation from industry. The extended discussions in the company of outstanding thinkers will stimulate and foster new science. The conference will include talks in the following areas: Alternative feedstocks for chemicals and fuels, Imaging and spectroscopy, Design of novel catalysts, Catalyst preparation fundamentals, Molecular insights through theory, Surface Science, Catalyst stability and dynamics. In 2010, the Catalysis conference will move to a larger conference room with a new poster session area that will allow 40 posters per session. The dorm rooms provide single and double accommodations, free WiFi and the registration fee includes all meals and the famous lobster dinner on Thursday night. Afternoons are open to enjoy the New England ambiance with opportunities for hiking, sailing, golf and tennis to create an outstanding conference that will help you network with colleagues, and make long lasting connections.

  16. Treatment of the liquid waste of the laboratories of the engineering Department by means of photo catalysis

    International Nuclear Information System (INIS)

    Porras, Paula; Avalos, Yasmin; Mejia, Gloria; Penuela, Gustavo

    2000-01-01

    In this paper are showed the results of wastewater treatment of CIA and ISA laboratories of engineering Department. Photo catalysis was used in treatment of wastewater, with a removal between 52% and 68% as chemical oxygen demand (COD) during 6 hours of photo degradation. In photo catalysis, TiO 2 , hydrogen peroxide and ultraviolet light were used

  17. Wavelength-Adaptive Dehazing Using Histogram Merging-Based Classification for UAV Images

    Directory of Open Access Journals (Sweden)

    Inhye Yoon

    2015-03-01

    Full Text Available Since incoming light to an unmanned aerial vehicle (UAV platform can be scattered by haze and dust in the atmosphere, the acquired image loses the original color and brightness of the subject. Enhancement of hazy images is an important task in improving the visibility of various UAV images. This paper presents a spatially-adaptive dehazing algorithm that merges color histograms with consideration of the wavelength-dependent atmospheric turbidity. Based on the wavelength-adaptive hazy image acquisition model, the proposed dehazing algorithm consists of three steps: (i image segmentation based on geometric classes; (ii generation of the context-adaptive transmission map; and (iii intensity transformation for enhancing a hazy UAV image. The major contribution of the research is a novel hazy UAV image degradation model by considering the wavelength of light sources. In addition, the proposed transmission map provides a theoretical basis to differentiate visually important regions from others based on the turbidity and merged classification results.

  18. Merging airborne and carborne radiometric data for surveying the Deir Az-Zor area, Syria

    International Nuclear Information System (INIS)

    Jubeli, Y.M.; Aissa, M.; Al-Hent, R.

    1997-01-01

    To complete the radiometric map of Syria, and to estimate the natural background radiation levels for environmental monitoring, a carborne survey was undertaken over the Deir Az-Zor area. This area was not covered by a previous airborne survey, except for peripheral regions in the south and west. To complete the radiometric map, results of the carborne and airborne surveys had to be merged. This paper presents the merging procedure which was used after normalizing the two data sets to match each other. No anomalies suitable for radioelement exploration were found. However, the overall radiometric maps resulting from the present work were consistent with the maps of the areas covered by the airborne survey. (author)

  19. Generation of high harmonic free electron laser with phase-merging effect

    Energy Technology Data Exchange (ETDEWEB)

    Li, Heting, E-mail: liheting@ustc.edu.cn; Jia, Qika; Zhao, Zhouyu

    2017-03-01

    An easy-to-implement scheme is proposed to produce the longitudinal electron bunch density modulation with phase-merging phenomenon. In this scheme an electron bunch is firstly transversely dispersed in a modified dogleg to generate the exact dependence of electron energy on the transverse position, then it is modulated in a normal modulator. After travelling through a modified chicane with specially designed transfer matrix elements, the density modulation with phase-merging effect is generated which contains high harmonic components of the seed laser. We present theoretical analysis and numerical simulations for seeded soft x-ray free-electron laser. The results demonstrate that this technique can significantly enhance the frequency up-conversion efficiency and allow a seeded FEL operating at very high harmonics.

  20. Wavelength-adaptive dehazing using histogram merging-based classification for UAV images.

    Science.gov (United States)

    Yoon, Inhye; Jeong, Seokhwa; Jeong, Jaeheon; Seo, Doochun; Paik, Joonki

    2015-03-19

    Since incoming light to an unmanned aerial vehicle (UAV) platform can be scattered by haze and dust in the atmosphere, the acquired image loses the original color and brightness of the subject. Enhancement of hazy images is an important task in improving the visibility of various UAV images. This paper presents a spatially-adaptive dehazing algorithm that merges color histograms with consideration of the wavelength-dependent atmospheric turbidity. Based on the wavelength-adaptive hazy image acquisition model, the proposed dehazing algorithm consists of three steps: (i) image segmentation based on geometric classes; (ii) generation of the context-adaptive transmission map; and (iii) intensity transformation for enhancing a hazy UAV image. The major contribution of the research is a novel hazy UAV image degradation model by considering the wavelength of light sources. In addition, the proposed transmission map provides a theoretical basis to differentiate visually important regions from others based on the turbidity and merged classification results.

  1. FROM GLOBALIZATION TO GLOBALITY- MERGING NON- WESTERN (POST COLONIAL AND WESTERN SOCIETIES INTO A GLOBAL MODERNITY

    Directory of Open Access Journals (Sweden)

    Angela Barakoska

    2014-12-01

    Full Text Available Modernity stands as a widely used term for social change as it involves modification in many forms in the society and the way people develop with different ideologies and movements. Standing on the other side of the traditional and historical, modernity brings new forms of development, communication and connectedness. In this paper it would be discussed whether the globalization processes are leading to merging of the societies and raising a global modernity, hence the influence of the West and the pilgrimages drawn on the other societies would be examined. Change is an unavoidable part of the society seen as a reform, reaction or revolution. However, the historical processes of integration, innovation and development bring different questions and theories. In this paper it would be referred on the integrative inclinations for merging societies, the understanding of modernity and globalization processes that emerge from the historical development and social change.

  2. Universality in the merging dynamics of parametric active contours: a study in MRI based lung segmentation

    International Nuclear Information System (INIS)

    Chattopadhyay, Amit K; Ray, Nilanjan; Acton, Scott T

    2005-01-01

    Measurement of lung ventilation is one of the most reliable techniques in diagnosing pulmonary diseases. The time-consuming and bias-prone traditional methods using hyperpolarized H 3 He and 1 H magnetic resonance imageries have recently been improved by an automated technique based on 'multiple active contour evolution'. This method involves a simultaneous evolution of multiple initial conditions, called 'snakes', eventually leading to their 'merging' and is entirely independent of the shapes and sizes of snakes or other parametric details. The objective of this paper is to show, through a theoretical analysis, that the functional dynamics of merging as depicted in the active contour method has a direct analogue in statistical physics and this explains its 'universality'. We show that the multiple active contour method has an universal scaling behaviour akin to that of classical nucleation in two spatial dimensions. We prove our point by comparing the numerically evaluated exponents with an equivalent thermodynamic model

  3. Navier-Stokes structure of merged layer flow on the spherical nose of a space vehicle

    Science.gov (United States)

    Jain, A. C.; Woods, G. H.

    1988-01-01

    Hypersonic merged layer flow on the forepart of a spherical surface of a space vehicle has been investigated on the basis of the full steady-state Navier-Stokes equations using slip and temperature jump boundary conditions at the surface and free-stream conditions far from the surface. The shockwave-like structure was determined as part of the computations. Using an equivalent body concept, computations were carried out under conditions that the Aeroassist Flight Experiment (AFE) Vehicle would encounter at 15 and 20 seconds in its flight path. Emphasis was placed on understanding the basic nature of the flow structure under low density conditions. Particular attention was paid to the understanding of the structure of the outer shockwave-like region as the fluid expands around the sphere. Plots were drawn for flow profiles and surface characteristics to understand the role of dissipation processes in the merged layer of the spherical nose of the vehicle.

  4. Merging of the USGS Atlas of Mercury 1:5,000,000 Geologic Series

    Science.gov (United States)

    Frigeri, A.; Federico, C.; Pauselli, C.; Coradini, A.

    2008-01-01

    After 30 years, the planet Mercury is going to give us new information. The NASA MESSENGER [1] already made its first successful flyby on December 2007 while the European Space Agency and the Japanese Space Agency ISAS/JAXA are preparing the upcoming mission BepiColombo [2]. In order to contribute to current and future analyses on the geology of Mercury, we have started to work on the production of a single digital geologic map of Mercury derived from the merging process of the geologic maps of the Atlas of Mercury, produced by the United States Geological Survey, based on Mariner 10 data. The aim of this work is to merge the nine maps so that the final product reflects as much as possible the original work. Herein we describe the data we used, the working environment and the steps made for producing the final map.

  5. Catalysis by Design Using Surface Organometallic Nitrogen-Containing Fragments

    KAUST Repository

    Hamzaoui, Bilel

    2016-06-14

    The aim of this thesis is to explore the chemistry of well-defined silica-supported group 4 and group 5 complexes that contain one or more multiply-bonded nitrogen atoms. Such species have been recognized as crucial intermediates in many catalytic reactions (e.g. hydroaminoalkylation, olefin hydrogenation, imine metathesis…). The first chapter provided a bibliographic overview of the preparation and the reactivity of group 4 and 5 complexes towards hydroaminoalkylation and imine metathesis catalysis. The second chapter deals with the isolation and the characterization of a series of well-defined group 4 ƞ2-imine complexes surfaces species. 2D solid-state NMR (1H–13C HETCOR, Multiple Quantum) experiments have revealed consistently a unique structural rearrangement, viz azametallacycle occurring on the immobilized metal-amido ligands. Hydrogenolysis of the sole Zr-C bond in such species gives selectively a silica-supported zirconium monohydride that can perform the catalytic hydrogenation of olefins. The third chapter examines the mechanistic studies of the intermolecular hydroaminoalkylation using SOMC to identify the key metallacyclic surface intermediates (silica-supported three-membred and five-membered). The catalyst was regenerated by protonolysis and afforded pure amine. Catalytic testing of a selection of amine compounds with variable electronic properties was carried out. The fourth chapter deals with the generation and the characterization of well-defined silica-supported zirconium-imido complexes. The resulting species effectively catalyzes imine/imine cross-metathesis and thus considered as the first heterogeneous catalysts active for imine metathesis reaction. The fifth chapter studies the reaction of SBA15.1100 ºC with dry aniline and derivatives leading to opening strained siloxane bridges into acid-base paired functionalities (formation of N-phenylsilanamine-silanol pairs). This approach was successfully applied to the design of a series of

  6. Perspectives on electrostatics and conformational motions in enzyme catalysis.

    Science.gov (United States)

    Hanoian, Philip; Liu, C Tony; Hammes-Schiffer, Sharon; Benkovic, Stephen

    2015-02-17

    CONSPECTUS: Enzymes are essential for all living organisms, and their effectiveness as chemical catalysts has driven more than a half century of research seeking to understand the enormous rate enhancements they provide. Nevertheless, a complete understanding of the factors that govern the rate enhancements and selectivities of enzymes remains elusive, due to the extraordinary complexity and cooperativity that are the hallmarks of these biomolecules. We have used a combination of site-directed mutagenesis, pre-steady-state kinetics, X-ray crystallography, nuclear magnetic resonance (NMR), vibrational and fluorescence spectroscopies, resonance energy transfer, and computer simulations to study the implications of conformational motions and electrostatic interactions on enzyme catalysis in the enzyme dihydrofolate reductase (DHFR). We have demonstrated that modest equilibrium conformational changes are functionally related to the hydride transfer reaction. Results obtained for mutant DHFRs illustrated that reductions in hydride transfer rates are correlated with altered conformational motions, and analysis of the evolutionary history of DHFR indicated that mutations appear to have occurred to preserve both the hydride transfer rate and the associated conformational changes. More recent results suggested that differences in local electrostatic environments contribute to finely tuning the substrate pKa in the initial protonation step. Using a combination of primary and solvent kinetic isotope effects, we demonstrated that the reaction mechanism is consistent across a broad pH range, and computer simulations suggested that deprotonation of the active site Tyr100 may play a crucial role in substrate protonation at high pH. Site-specific incorporation of vibrational thiocyanate probes into the ecDHFR active site provided an experimental tool for interrogating these microenvironments and for investigating changes in electrostatics along the DHFR catalytic cycle

  7. Nanoporous gold membranes: From morphological control to fuel cell catalysis

    Science.gov (United States)

    Ding, Yi

    Porous noble metals are particularly attractive for scientific research and industrial applications such as catalysis, sensing, and filtration. In this thesis, I will discuss the fabrication, characterization, and application of a new class of porous metals, called nanoporous metals (NPM). NPM is made during selective dissolution (also called dealloying) of reactive components (e.g., silver) from multi-component alloys (e.g., Ag/Au alloy). Commercially available white gold leaf (Ag65Au35) can, for example, be etched into nanoporous gold (NPG) membrane by simply floating the leaf on concentrated nitric acid for periods of a few minutes. NPG leaf adopts a single crystal porous structure within individual grains. The microstructure of NPG, such as the pore size, is tunable between a few nanometers to sub-micron length scale by either thermal annealing or post-treatment in nitric acid for extended period of time. A new gas-liquid-solid interface electroless plating technique is developed to uniformly cover the NPG surface with other metals, such as silver and platinum. This technique allows new opportunities of making functionalized nanostructures. We show that a combination of silver plating and dealloying can be used to make multimodal porous metals, which are expected to have application in sensing field. Electroless platinum plating onto NPG shows very usual growth mode. TEM observation indicates that the platinum layer on NPG surface takes a novel form of layer-islanding growth (Stranski-Krastanov growth). Annealing the Pt/NPG composite smoothens the Pt islands and forms a 1 nm coherent Pt layer on the NPG backbone, possibly with dislocation formation at the Pt/Au interface. Furthermore, it was found that we could dissolve the gold away in aqueous gold etchant, leaving behind the 1 nm-thick Pt shell, a structure we call nanotubular mesoporous platinum (NMP). Pt plated NPG has a series of unique structural properties, such as high active surface area, thermally

  8. Metal nanoparticles in liquid phase catalysis; from recent advances to future goals.

    Science.gov (United States)

    Zahmakıran, Mehmet; Ozkar, Saim

    2011-09-01

    Metal nanoparticles have attracted much attention over the last decade owing to their unique properties, different to their bulk counterparts, which pave the way for their application in different fields from materials science and engineering to biomedical applications. Of particular interest, the use of metal nanoparticles in catalysis has brought superior efficiency in terms of activity, selectivity and lifetime to heterogeneous catalysis. This article reviews the recent developments in the synthesis routes and the catalytic performance of metal nanoparticles depending on the solvent used for various organic and inorganic transformations. Additionally, we also discuss the prevalent complications and their possible solutions plus future prospects in the field of nanocatalysis.

  9. Growth mechanism of graphene on platinum: Surface catalysis and carbon segregation

    International Nuclear Information System (INIS)

    Sun, Jie; Lindvall, Niclas; Yurgens, August; Nam, Youngwoo; Cole, Matthew T.; Teo, Kenneth B. K.; Woo Park, Yung

    2014-01-01

    A model of the graphene growth mechanism of chemical vapor deposition on platinum is proposed and verified by experiments. Surface catalysis and carbon segregation occur, respectively, at high and low temperatures in the process, representing the so-called balance and segregation regimes. Catalysis leads to self-limiting formation of large area monolayer graphene, whereas segregation results in multilayers, which evidently “grow from below.” By controlling kinetic factors, dominantly monolayer graphene whose high quality has been confirmed by quantum Hall measurement can be deposited on platinum with hydrogen-rich environment, quench cooling, tiny but continuous methane flow and about 1000 °C growth temperature

  10. Enzyme catalysis: a new definition accounting for noncovalent substrate- and product-like states.

    Science.gov (United States)

    Purich, D L

    2001-07-01

    Biological catalysis frequently causes changes in noncovalent bonding. By building on Pauling's assertion that any long-lived, chemically distinct interaction is a chemical bond, this article redefines enzyme catalysis as the facilitated making and/or breaking of chemical bonds, not just of covalent bonds. It is also argued that nearly every ATPase or GTPase is misnamed as a hydrolase and actually belongs to a distinct class of enzymes, termed here 'energases'. By transducing covalent bond energy into mechanical work, energases mediate such fundamental processes as protein folding, self-assembly, G-protein interactions, DNA replication, chromatin remodeling and even active transport.

  11. Microbiological and ecological responses to global environmental changes in polar regions (MERGE): An IPY core coordinating project

    Science.gov (United States)

    Naganuma, Takeshi; Wilmotte, Annick

    2009-11-01

    An integrated program, “Microbiological and ecological responses to global environmental changes in polar regions” (MERGE), was proposed in the International Polar Year (IPY) 2007-2008 and endorsed by the IPY committee as a coordinating proposal. MERGE hosts original proposals to the IPY and facilitates their funding. MERGE selected three key questions to produce scientific achievements. Prokaryotic and eukaryotic organisms in terrestrial, lacustrine, and supraglacial habitats were targeted according to diversity and biogeography; food webs and ecosystem evolution; and linkages between biological, chemical, and physical processes in the supraglacial biome. MERGE hosted 13 original and seven additional proposals, with two full proposals. It respected the priorities and achievements of the individual proposals and aimed to unify their significant results. Ideas and projects followed a bottom-up rather than a top-down approach. We intend to inform the MERGE community of the initial results and encourage ongoing collaboration. Scientists from non-polar regions have also participated and are encouraged to remain involved in MERGE. MERGE is formed by scientists from Argentina, Australia, Austria, Belgium, Brazil, Bulgaria, Canada, Egypt, Finland, France, Germany, Italy, Japan, Korea, Malaysia, New Zealand, Philippines, Poland, Russia, Spain, UK, Uruguay, USA, and Vietnam, and associates from Chile, Denmark, Netherlands, and Norway.

  12. Massively Parallel Sort-Merge Joins in Main Memory Multi-Core Database Systems

    OpenAIRE

    Martina-Cezara Albutiu, Alfons Kemper, Thomas Neumann

    2012-01-01

    Two emerging hardware trends will dominate the database system technology in the near future: increasing main memory capacities of several TB per server and massively parallel multi-core processing. Many algorithmic and control techniques in current database technology were devised for disk-based systems where I/O dominated the performance. In this work we take a new look at the well-known sort-merge join which, so far, has not been in the focus of research ...

  13. Towards a merged satellite and in situ fluorescence ocean chlorophyll product

    OpenAIRE

    Lavigne, H.; D'Ortenzio, F.; Claustre, H.; Poteau, A.

    2012-01-01

    Understanding the ocean carbon cycle requires a precise assessment of phytoplankton biomass in the oceans. In terms of numbers of observations, satellite data represents the largest available data set. However, as they are limited to surface waters, they have to be merged with in situ observations. Amongst the in situ data, fluorescence profiles constitute the greatest data set available, because fluorometers operate routinely on oceanographic cruise since the seventies. Nevertheless,...

  14. A cluster merging method for time series microarray with production values.

    Science.gov (United States)

    Chira, Camelia; Sedano, Javier; Camara, Monica; Prieto, Carlos; Villar, Jose R; Corchado, Emilio

    2014-09-01

    A challenging task in time-course microarray data analysis is to cluster genes meaningfully combining the information provided by multiple replicates covering the same key time points. This paper proposes a novel cluster merging method to accomplish this goal obtaining groups with highly correlated genes. The main idea behind the proposed method is to generate a clustering starting from groups created based on individual temporal series (representing different biological replicates measured in the same time points) and merging them by taking into account the frequency by which two genes are assembled together in each clustering. The gene groups at the level of individual time series are generated using several shape-based clustering methods. This study is focused on a real-world time series microarray task with the aim to find co-expressed genes related to the production and growth of a certain bacteria. The shape-based clustering methods used at the level of individual time series rely on identifying similar gene expression patterns over time which, in some models, are further matched to the pattern of production/growth. The proposed cluster merging method is able to produce meaningful gene groups which can be naturally ranked by the level of agreement on the clustering among individual time series. The list of clusters and genes is further sorted based on the information correlation coefficient and new problem-specific relevant measures. Computational experiments and results of the cluster merging method are analyzed from a biological perspective and further compared with the clustering generated based on the mean value of time series and the same shape-based algorithm.

  15. Preparation of Phased and Merged Safety Analysis Reports for New DOE Nuclear Facilities

    International Nuclear Information System (INIS)

    BISHOP, G.E.

    2000-01-01

    The Spent Nuclear Fuels Project (SNFP) is charged with moving to storage 2,100 metric tons of spent nuclear fuel elements left over from plutonium production at DOE'S Hanford site in Washington state. Two new facilities, the Cold Vacuum Drying Facility (CVDF) and the Canister Storage Building (CSB) are in final construction. In order to meet aggressive schedule commitments, the SNFP chose to prepare the safety analysis reports (SAR's) in phases that covered only specific portions of each facility's design as it was built. Each SAR also merged the preliminary and final safety analysis reports into a single SAR, thereby covering all aspects of design, construction, and operation for that portion (phase) of the facility. A policy of ''NRC equivalency'' was also implemented in parallel with this effort, with the goal of achieving a rigor of safety analysis equivalent to that of NRC-licensed fuel processing facilities. DOE Order 5480.23. ''Nuclear Safety Analysis Reports'' allows preparation of both a phased and a merged SAR to accelerate construction schedules. However, project managers must be aware that such acceleration is not guaranteed. Managers considering this approach for their project should be cognizant of numerous obstacles that will be encountered. Merging and phasing SAR's will create new, unique, and unanticipated difficulties which may actually slow construction unless expeditiously and correctly managed. Pitfalls to be avoided and good practices to be implemented in preparing phased and merged SAR's are presented. The value of applying NRC requirements to the DOE safety analysis process is also discussed. As of December, 1999, the SNFP has completed and approved a SAR for the CVDF. Approval of the SAR for the CSB is pending

  16. Joint optimization: Merging a new culture with a new physical environment.

    Science.gov (United States)

    Stichler, Jaynelle F; Ecoff, Laurie

    2009-04-01

    Nearly $200 billion of healthcare construction is expected by the year 2015, and nurse leaders must expand their knowledge and capabilities in healthcare design. This bimonthly department prepares nurse leaders to use the evidence-based design process to ensure that new, expanded, and renovated hospitals facilitate optimal patient outcomes, enhance the work environment for healthcare providers, and improve organizational performance. In this article, the authors discuss the concept of joint optimization of merging organizational culture with a new hospital facility.

  17. Decomposition recovery extension to the Computer Aided Prototyping System (CAPS) change-merge tool.

    OpenAIRE

    Keesling, William Ronald

    1997-01-01

    Approved for public release; distribution is unlimited A promising use of Computer Aided Prototyping System (CAPS) is to support concurrent design. Key to success in this context is the ability to automatically and reliably combine and integrate the prototypes produced in concurrent efforts. Thus, to be of practical use in this as well as most prototyping contexts, a CAPS tool must have a fast, automated, reliable prototype integration capability. The current CAPS Change Merge Tool is fast...

  18. The importance of executive leadership in creating a post-merged organisational culture conducive to effective performance management

    Directory of Open Access Journals (Sweden)

    Gary W. Paul

    2013-01-01

    Full Text Available Orientation: Focus was placed on the important role of executive management in creating a post-merged organisational culture conducive to effective performance management.Research purpose: To develop a theoretical model from the insights gleaned from the literature study, interviews with senior human resource (HR practitioners at participating institutions and the empirical study. Based on the empirical findings, this model was refined and resulted in the eight-step integrated post-merged organisational culture creation model.Motivation for the study: The negligible attention given to the design of mechanisms supportive of post-merged organisational culture creation emphasised the need for this study. The high percentage of merger failures attributable to ineffective post-merged organisational culture integration further contributed.Research design, approach and method: A quantitative study was conducted at three merged South African higher education institutions, namely Nelson Mandela Metropolitan University, Cape Peninsula University of Technology and Durban University of Technology. Respondents occupied the following functional categories: executive management, senior and line management, HR practitioners and non-HR or non-management.Main findings: Respondents perceived the role of executive management to be the most important step of the theoretical model which formed the basis for the empirical survey questionnaire. This step, which obtained the highest summated mean score in all three institutions and across all functional categories, was depicted as Step 5 of the model.Practical/managerial implications: The refined eight-step integrated post-merged organisational culture creation model will significantly enhance the creation of a post-merged organisational culture conducive to effective performance management.Contribution/value-add: This study addressed the void regarding a model to guide the creation of a post-merged organisational

  19. Data merging of infrared and ultrasonic images for plasma facing components inspection

    Energy Technology Data Exchange (ETDEWEB)

    Richou, M. [CEA, IRFM, F-13108 Saint Paul-lez-Durance (France)], E-mail: marianne.richou@cea.fr; Durocher, A. [CEA, IRFM, F-13108 Saint Paul-lez-Durance (France); Medrano, M. [Association EURATOM - CIEMAT, Avda. Complutense 22, 28040 Madrid (Spain); Martinez-Ona, R. [Tecnatom, 28703 S. Sebastian de los Reyes, Madrid (Spain); Moysan, J. [LCND, Universite de la Mediterranee, F-13625 Aix-en-Provence (France); Riccardi, B. [Fusion For Energy, 08019 Barcelona (Spain)

    2009-06-15

    For steady-state magnetic thermonuclear fusion devices which need large power exhaust capability, actively cooled plasma facing components have been developed. In order to guarantee the integrity of these components during the required lifetime, their thermal and mechanical behaviour must be assessed. Before the procurement of the ITER Divertor, the examination of the heat sink to armour joints with non-destructive techniques is an essential topic to be addressed. Defects may be localised at different bonding interfaces. In order to improve the defect detection capability of the SATIR technique, the possibility of merging the infrared thermography test data coming from SATIR results with the ultrasonic test data has been identified. The data merging of SATIR and ultrasonic results has been performed on Carbon Fiber Composite (CFC) monoblocks with calibrated defects, identified by their position and extension. These calibrated defects were realised with machining, with 'stop-off' or by a lack of CFC activation techniques, these last two representing more accurately a real defect. A batch of 56 samples was produced to simulate each possibility of combination with regards to interface location, position and extension and way of realising the defect. The use of a data merging method based on Dempster-Shafer theory improves significantly the detection sensibility and reliability of defect location and size.

  20. Data merging of infrared and ultrasonic images for plasma facing components inspection

    International Nuclear Information System (INIS)

    Richou, M.; Durocher, A.; Medrano, M.; Martinez-Ona, R.; Moysan, J.; Riccardi, B.

    2009-01-01

    For steady-state magnetic thermonuclear fusion devices which need large power exhaust capability, actively cooled plasma facing components have been developed. In order to guarantee the integrity of these components during the required lifetime, their thermal and mechanical behaviour must be assessed. Before the procurement of the ITER Divertor, the examination of the heat sink to armour joints with non-destructive techniques is an essential topic to be addressed. Defects may be localised at different bonding interfaces. In order to improve the defect detection capability of the SATIR technique, the possibility of merging the infrared thermography test data coming from SATIR results with the ultrasonic test data has been identified. The data merging of SATIR and ultrasonic results has been performed on Carbon Fiber Composite (CFC) monoblocks with calibrated defects, identified by their position and extension. These calibrated defects were realised with machining, with 'stop-off' or by a lack of CFC activation techniques, these last two representing more accurately a real defect. A batch of 56 samples was produced to simulate each possibility of combination with regards to interface location, position and extension and way of realising the defect. The use of a data merging method based on Dempster-Shafer theory improves significantly the detection sensibility and reliability of defect location and size.