Sample records for well-defined pnipam-b-pea-g-p2vp double


    DEFF Research Database (Denmark)


    A method for the synthesis of dendrimer conjugates having a well-defined chemical structure, comprising one or more carbohydrate moieties and one or more immunomodulating substances coupled to a dendrimer, is presented. First, the carbohydrate is bound to the dendrimer in a chemoselective manner....... Subsequently, the immunomodulating substance is also bound in a chemoselective manner, to give a dendrimer conjugate with a well-defined structure and connectivity and containing a precise, pre-determined ratio of carbohydrate to immunomodulating substance. The invention also relates to novel dendrimer...

  2. Well-defined transition metal hydrides in catalytic isomerizations. (United States)

    Larionov, Evgeny; Li, Houhua; Mazet, Clément


    This Feature Article intends to provide an overview of a variety of catalytic isomerization reactions that have been performed using well-defined transition metal hydride precatalysts. A particular emphasis is placed on the underlying mechanistic features of the transformations discussed. These have been categorized depending upon the nature of the substrate and in most cases discussed following a chronological order.

  3. Well-defined side-chain liquid-crystalline polysiloxanes

    NARCIS (Netherlands)

    Hempenius, Mark A.; Lammertink, Rob G.H.; Vancso, Gyula J.


    A route to well-defined side-chain liquid-crystalline polysiloxanes (ratio of weight-to number-average molar masses Mw/Mn < 1.2 is reported. Anionic ring-opening polymerization of pentamethylvinylcyclotrisiloxane yielded a poly(dimethylsiloxane-co-methylvinylsiloxane) backbone. A flexible disiloxane

  4. A generic synthesis algorithm for well-defined parametric design

    NARCIS (Netherlands)

    Schotborgh, W.O.; Kokkeler, Frans; Tragter, Hendrik; Bomhoff, M.J.; van Houten, Frederikus J.A.M.; van Houten, F.J.A.M.; Miedema, J.; Lutters, D.


    This paper aims to improve the way synthesis tools can be built by formalizing: 1) the design artefact, 2) related knowledge and 3) an algorithm to generate solutions. This paper focuses on well-defined parametric engineering design, ranging from machine elements to industrial products. A design

  5. Well-defined (co)polypeptides bearing pendant alkyne groups

    KAUST Repository

    Zhao, Wei


    A novel metal-free strategy, using hydrogen-bonding catalytic ring opening polymerization of acetylene-functionalized N-carboxy anhydrites of α-amino acids, was developed for the synthesis of well-defined polypeptides bearing pendant alkyne groups. This method provides an efficient way to synthesize novel alkyne-functionalized homopolypeptides (A) and copolypeptides, such as AB diblock (B: non-functionalized), ABA triblock and star-AB diblock, as well as linear and star random copolypeptides, precursors of a plethora complex macromolecular architectures by click chemistry.

  6. A well-defined rhenium(VII) olefin metathesis catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Toreki, R.; Schrock, R.R. (Massachusetts Institute of Technology, Cambridge (USA))


    Molybdenum tungsten, and rhenium are the three most active metals in classical olefin metathesis systems. Molybdenum (VI){sup 2} and tungsten(VI){sup 3} alkylidene complexes of the type M-(CHR{prime})(NAr)(OR){sub 2} (Ar = 2,6-C{sub 6}H{sub 3}-i-Pr{sub 2}) have been shown to be well-behaved olefin metathesis catalysts with an activity that can be controlled through the choice of OR. Although several rhenium alkylidene complexes have been reported, none has shown any confirmable metathesis activity, even toward strained cyclic olefins such as norbornene. Since Re{triple bond}CR{double prime} and M{double bond}NR{double prime} (M = Mo or W) can be regarded as isoelectronic units, plausible candidates as olefin metathesis catalysts are complexes of the type Re(CHR{prime})(CR{double prime})(OR){sub 2}. The authors report here that such a complex in which OR = OCMe(CF{sub 3}){sub 2} is a well-behaved olefin metathesis catalyst.

  7. Supramolecular Diblock Copolymers Featuring Well-defined Telechelic Building Blocks. (United States)

    Elacqua, Elizabeth; Croom, Anna; Manning, Kylie B; Pomarico, Scott K; Lye, Diane; Young, Lauren; Weck, Marcus


    We report supramolecular AB diblock copolymers comprised of well-defined telechelic building blocks. Helical motifs, formed via reversible addition-fragmentation chain-transfer (RAFT) or anionic polymerization, are assembled with coil-forming and sheet-featuring blocks obtained via atom-transfer radical polymerization (ATRP) or ring-opening metathesis polymerization (ROMP). Interpolymer hydrogen bonding or metal-coordination achieves dynamic diblock architectures featuring hybrid topologies of coils, helices, and/or π-stacked sheets that, on a basic level, mimic protein structural motifs in fully synthetic systems. The intrinsic properties of each block (e.g., circular dichroism and fluorescence) remain unaffected in the wake of self-assembly. This strategy to develop complex synthetic polymer scaffolds from functional building blocks is significant in a field striving to produce architectures reminiscent of biosynthesis, yet fully synthetic in nature. This is the first plug-and-play approach to fabricate hybrid π-sheet/helix, π-sheet/coil, and helix/coil architectures via directional self-assembly. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Efficient Construction of Well-Defined Multicompartment Porous Systems in a Modular and Chemically Orthogonal Fashion. (United States)

    Gao, Ning; Tian, Tian; Cui, Jiecheng; Zhang, Wanlin; Yin, Xianpeng; Wang, Shiqiang; Ji, Jingwei; Li, Guangtao


    A microfluidic assembly approach was developed for efficiently producing hydrogel spheres with reactive multidomains that can be employed as an advantageous platform to create spherical porous networks in a facile manner with well-defined multicompartments and spatiotemporally controlled functions. This strategy allows for not only large scale fabrication of various robust hydrogel microspheres with controlled size and porosity, but also the domains embedded in hydrogel network could be introduced in a modular manner. Additionally, the number of different domains and their ratio could be widely variable on demand. More importantly, the reactive groups distributed in individual domains could be used as anchor sites to further incorporate functional units in an orthogonal fashion, leading to well-defined multicompartment systems. The strategy provides a new and efficient route to construct well-defined functional multicompartment systems with great flexibility and extendibility. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. One-pot synthesis of well-defined oligo- butadiynylene-naphthalene diimides. (United States)

    Yue, Wan; Zhen, Yonggang; Li, Yan; Jiang, Wei; Lv, Aifeng; Wang, Zhaohui


    A homogeneous series of well-defined oligo-butadiynylene-NDIs containing up to five naphthalene diimides (NDIs) moieties have been efficiently synthesized in one pot by oxidative homocoupling of 1,6-di((trimethylsilyl)ethynyl)naphthalene diimides in good yields.

  10. Synthesis and Characterization of Well-Defined Regular Star Polyisoprenes with 3, 4, 6 and 8 Arms

    KAUST Repository

    Ratkanthwar, Kedar R.


    Three series of regular well-defined star polyisoprenes (PIs) with 3, 4 and 6 arms (each series: same arm molecular weight) have been synthesized by anionic polymerization high vacuum techniques and chlorosilane chemistry. In addition, three linear PIs with practically the double arm molecular weight of the corresponding series (2-arm star PIs) have been synthesized, as well as one 8-arm star PI. All intermediate (arms) and final (stars) products have been characterized by size exclusion chromatography (SEC), SEC-multi-angle laser light scattering (SEC-MALLS) and nuclear magnetic resonance (NMR) spectroscopy. The Tg of the star PIs was determined by differential scanning calorimetry. These model polymeric materials are essential for polymer physics and polymer physical chemistry in order to establish the structure/property relationships.

  11. Synthesis of well-defined catechol polymers for surface functionalization of magnetic nanoparticles


    Zhang, Qiang; Nurumbetov, Gabit; Simula, Alexandre; Zhu, Chongyu; Li, Muxiu; Wilson, Paul; Kempe, Kristian; Yang, Bin; tao, lei; Haddleton, David M.


    In order to obtain dual-modal fluorescent magnetic nanoparticles, well-defined fluorescent functional polymers with terminal catechol groups were synthesized by single electron transfer living radical polymerization (SET-LRP) under aqueous conditions for “grafting to” modification of iron oxide nanoparticles. Acrylamide, N-isopropylacrylamide, poly(ethylene glycol) methyl ether acrylate, 2-hydroxyethyl acrylate, glycomonomer and rhodamine B piperazine acrylamide were homo-polymerized or block...

  12. Pengaruh Pendekatan Pengajaran dan Tipe Masalah Terhadap Kemampuan Pemecahan Masalah Tipe ILL dan WELL-DEFINED


    Demitra Demitra


    This study focuses on examining the effects of teaching approaches (problem-based learning v.s. regular) and types of problem (ill defined v.s. well defined) on Matematical problem solving abilities. This quasi-experimental study involved 107 elementary school students, who had been randomly selected from 635 clustered students. MANCOVA analysis of pretest and posttest result indicates that there is an interactional effect of teaching approaches and types of problem on problem solving abiliti...

  13. Pengaruh Pendekatan Pengajaran dan Tipe Masalah terhadap Kemampuan Pemecahan Masalah Tipe ILL dan WELL-DEFINED


    Demitra, Demitra


    This study focuses on examining the effects of teaching approaches (problem-based learning v.s. regular) and types of problem (ill defined v.s. well defined) on Matematical problem solving abilities. This quasi-experimental study involved 107 elementary school students, who had been randomly selected from 635 clustered students. MANCOVA analysis of pretest and posttest result indicates that there is an interactional effect of teaching approaches and types of problem on problem solving abiliti...

  14. Well-defined polyethylene molecular brushes by polyhomologation and ring opening metathesis polymerization

    KAUST Repository

    Zhang, Hefeng


    A novel strategy using polyhomologation and ring opening metathesis polymerization (ROMP) has been developed for the synthesis of well-defined polyethylene (PE) molecular brushes. Polyhomologation was used to afford an OH-terminated PE, which after transformation to the norbornyl PE macromonomer was subjected to ROMP. Kinetics of ROMP of the PE macromonomer was studied by in situ1H NMR monitoring. The brush structure was proved from HT-GPC, 1H NMR and DSC results.

  15. Living Polycondensation: Synthesis of Well-Defined Aromatic Polyamide-Based Polymeric Materials

    KAUST Repository

    Alyami, Mram Z.


    Chain growth condensation polymerization is a powerful tool towards the synthesis of well-defined polyamides. This thesis focuses on one hand, on the synthesis of well-defined aromatic polyamides with different aminoalkyl pendant groups with low polydispersity and controlled molecular weights, and on the other hand, on studying their thermal properties. In the first project, well-defined poly (N-octyl-p-aminobenzoate) and poly (N-butyl-p-aminobenzoate) were synthesized, and for the first time, their thermal properties were studied. In the second project, ethyl4-aminobenzoate, ethyl 4-octyl aminobenzoate and 4-(hydroxymethyl) benzoic acid were used as novel efficient initiators of ε-caprolactone with t-BuP2 as a catalyst. Macroinitiator and Macromonomer of poly (ε-caprolactone) were synthesized with ethyl 4-octyl aminobenzoate and ethyl 4-aminobenzoate as initiators to afford polyamide-block-poly (ε-caprolactone) and polyamide-graft-poly (ε-caprolactone) by chain growth condensation polymerization (CGCP). In the third project, a new study has been done on chain growth condensation polymerization to discover the probability to synthesize new polymers and studied their thermal properties. For this purpose, poly (N-cyclohexyl-p-aminobenzoate) and poly (N-hexyl-p-aminobenzoate) were synthesized with low polydispersity and controlled molecular weights.

  16. Well-defined silica-supported zirconium–imido complexes mediated heterogeneous imine metathesis

    KAUST Repository

    Hamzaoui, Bilel


    Upon prolonged thermal exposure under vacuum, a well-defined single-site surface species [(≡Si-O-)Zr(NEt2)3] (1) evolves into an ethylimido complex [(≡Si-O-)Zr(=NEt)NEt2] (2). Reactions of 2 with an imine substrate result in imido/imine (=NRi, R: Et, Ph) exchange (metathesis) with the formation of [(≡Si-O-)Zr(=NPh)NEt2] (3). Compounds 2 and 3 effectively catalyze imine/imine cross-metathesis and are thus considered as the first heterogeneous catalysts active for imine metathesis. © The Royal Society of Chemistry 2016.

  17. Well-Defined Copper(I) Fluoroalkoxide Complexes for Trifluoroethoxylation of Aryl and Heteroaryl Bromides

    KAUST Repository

    Huang, Ronglu


    © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Copper(I) fluoroalkoxide complexes bearing dinitrogen ligands were synthesized and the structure and reactivity of the complexes toward trifluoroethoxylation, pentafluoropropoxylation, and tetrafluoropropoxylation of aryl and heteroaryl bromides were investigated. Efficiency drive: A series of copper(I) fluoroalkoxide complexes bearing N,N ligands have been prepared and structurally characterized. These well-defined complexes serve as efficient reagents for the fluoroalkoxylation of aryl and heteroaryl bromides to produce a wide range of trifluoroethyl, pentafluoropropyl, and tetrafluoropropyl (hetero)aryl ethers in good to excellent yields.

  18. Dichotomous Well-defined Nanostructure with Weakly Arranged Ion Packing Explains the Solvency of Pyrrolidinium Acetate. (United States)

    Jiang, Haihui Joy; Imberti, Silvia; Atkin, Rob; Warr, Gregory G


    Pyrrolidinium ionic liquids, especially pyrrolidinium acetate (PyrrAc), have demonstrated outstanding capacity for extracting lignin from biomass, as electrolytes for fuel cells and lithium ion batteries and as solvents for acid-catalyzed reactions. In this work we show that the unusual liquid nanostructure of PyrrAc is the key to its versatility as a solvent compared to other ionic liquids. Neutron diffraction with multiple H/D isotopic substitutions reveals that the bulk nanostructure of PyrrAc is a bicontinuous network of interpenetrating polar and apolar domains. However, the arrangement of groups in both domains is strikingly different from that found in other ionic liquids. In the apolar regions, the pyrrolidinium rings are highly intercalated and disordered, with no preferred alignment between adjacent pyrrolidinium rings, which distinguishes it from both π-π stacking seen in imidazolium or pyridinium ionic liquids, and the tail-tail bilayer-like arrangements in linear alkylammonium ionic liquids. The H-bond network within the polar domain extends only to form finite clusters, with long bent H-bonds to accommodate electrostatics. Therefore, while PyrrAc unquestionably has well-defined amphiphilic nanostructure, the disordered arrangement of groups in the polar and apolar domains enables it to accommodate a wide variety of solutes. The combination of well-defined polar/apolar nanostructure, but disordered arrangements of groups within domains, is therefore the origin of PyrrAc's capacity for lignin extraction and as an electrolyte.

  19. Large and well-defined Rabi splitting in a semiconductor nanogap cavity. (United States)

    Uemoto, Mitsuharu; Ajiki, Hiroshi


    We propose a nanogap structure composed of semiconductor nanoparticles forming an optical cavity. The resonant excitation of excitons in the nanoparticles can generate a localized strong light field in the gap region, also called "hot spot". The spectral width of the hot spot is significantly narrow because of the small exciton damping and the dephasing at low temperature, so the semiconductor nanogap structure acts as a high-Q cavity. In addition, the interaction between light and matter at the nanogap is significantly larger than that in a conventional microcavity, because the former has a small cavity-mode volume beyond the diffraction limit. We theoretically demonstrate the large and well-defined vacuum-Rabi splitting of a two-level emitter placed inside the semiconductor nanogap cavity: the Rabi splitting energy of 1.7 meV for the transition dipole moment of the emitter (25 Debye) is about 6.3 times larger than the spectral width. An optical cavity providing such a large and well-defined Rabi splitting is highly suited for studying characteristic features of the cavity quantum electrodynamics and for the development of new applications.

  20. Challenging nature's monopoly on the creation of well-defined nanoparticles. (United States)

    Jeong, Wonhee; Napier, Mary E; DeSimone, Joseph M


    Nature has selected and fine-tuned the physical and chemical properties of natural objects, such as size, shape, mechanical properties and surface chemistry, at the molecular level in order to modulate biological functions. A new particle fabrication process, particle replication in nonwetting templates (PRINT), has recently begun to attempt to emulate nature's ability to control those physical and chemical traits. The PRINT technology, which combines modern soft lithography with the unique properties of perfluoropolyether molds, enables the production of nanoparticles with unprecedented control of size, shape, chemical composition, deformability and surface functionality. This scalable 'top-down' fabrication process allows for the generation of well-defined nanostructures without the need for molecular assembly. The ability to flexibly engineer various matrix materials offers unique opportunities for the development of nanomedicines with desired functionality. The strength and versatility of PRINT makes it a powerful platform in nanomedicine for elucidating the role of physical and chemical properties of nanodelivery vehicles on the behavior and fate at the cellular, tissue and whole organism level. Utilizing the PRINT technology, we are generating well-defined nanomedicines with tailored properties for preclinical studies against a variety of human diseases.

  1. Well-defined and biocompatible hydrogels with toughening and reversible photoresponsive properties. (United States)

    Sun, Zhiqiang; Liu, Shunli; Li, Kewen; Tan, Linhua; Cen, Lian; Fu, Guodong


    In the present study, novel hydrogels with extremely high strength, reversible photoresponsive and excellent biocompatible properties were prepared. The functional hydrogels were synthesized from a well-defined poly (ethylene glycol) polymer with spiropyran groups at a given position (PEG-SP) via a Cu(i)-catalyst Azide-Alkyne Cycloaddition (CuAAC) reaction. The molecular structures of the sequential intermediates for PEG-SP hydrogel preparation were verified by (1)HNMR and FT-IR. The mechanical property, swelling ratio, compression strength, surface hydrophilicity, and biocompatibility of the resulting hydrogel were characterized. Since spiropyran is pivotal to the switch in hydrophilicity on the hydrogel surface, the swelling ratio of PEG-SP hydrogel under Vis irradiation has a major decrease (155%). Before and after UV light irradiation, the contact angle of the hydrogel has a change of 13.8°. The photoresponsive property of this hydrogel was thus demonstrated, and such a property was also shown to be reversible. The well-defined PEG-SP hydrogel can also sustain a compressive stress of 49.8 MPa without any macro- or micro-damage, indicating its outstanding mechanical performance. Furthermore, it possessed excellent biocompatibility as demonstrated by its performance in an in vivo porcine subcutaneous implantation environment. No inflammation was observed and it got along well with the adjacent tissue. The above features indicate that PEG-SP hydrogels are promising as an implantable matrix for potential applications in biomaterial.

  2. Amphiphilic conjunct of methyl cellulose and well-defined polyvinyl acetate. (United States)

    Xiao, Congming; Xia, Cunping


    Tailor-made conjunct of methyl cellulose (MC) and polyvinyl acetate (PVAc) was synthesized through the combination of reversible addition-fragmentation chain transfer (RAFT) polymerization and thiol-ene click reaction. MC was firstly transferred into unsaturated MC (UMC), and then covalently connected with well-defined PVAc obtained by RAFT polymerization of vinyl acetate. The structure of the conjunct polymer (MCV) was confirmed with Fourier transform infrared spectra (FTIR) and proton nuclear magnetic resonance ((1)H NMR). Well-defined MCV was amphiphilic and able to self-assemble into size controllable micelles, which was verified with transmission electron microscopy (TEM) and size distribution analysis. It was found that the mean diameters of the micelles in aqueous solution were 105.6, 96.0 and 75.9 nm when the number average molecular weights of PVAc segments of MCV were 49,300, 32,500 and 18,200, respectively. Copyright © 2012 Elsevier B.V. All rights reserved.

  3. Formation and stability of small well-defined Cu- and Ni oxide particles

    Energy Technology Data Exchange (ETDEWEB)

    Thalinger, Ramona [Institute of Physical Chemistry, University of Innsbruck, A-6020 Innsbruck (Austria); Heggen, Marc; Stroppa, Daniel G. [Ernst Ruska Zentrum und Peter Grünberg Institut, Forschungszentrum Jülich GmbH, 52425 Jülich (Germany); Stöger-Pollach, Michael [University Service Facility for Transmission Electron Microscopy (USTEM), Vienna University of Technology, A-1040 Vienna (Austria); Klötzer, Bernhard [Institute of Physical Chemistry, University of Innsbruck, A-6020 Innsbruck (Austria); Penner, Simon, E-mail: [Institute of Physical Chemistry, University of Innsbruck, A-6020 Innsbruck (Austria)


    Well-defined and -structured Cu/Cu{sub 2}O and Ni/NiO composite nanoparticles have been prepared by physical-vapor deposition on vacuum-cleaved NaCl(001) single crystal facets. Epitaxial growth has been observed due to the close crystallographic matching of the respective cubic crystal lattices. Distinct particle morphologies have only been obtained for the Ni/NiO particles, comprising truncated half-octahedral, rhombohedral- and pentagonal-shaped outlines. Oxidation of the particles in the temperature range 473–673 K in both cases led to the formation of well-defined CuO and NiO particles with distinct morphologies. Whereas CuO possibly adopts its thermodynamical equilibrium shape, NiO formation is accompanied by entering a Kirkendall-like state, that is, a hollow core–shell structure is obtained. The difference in the formation of the oxides is also reflected by their stability under reducing conditions. CuO transforms back to a polycrystalline mixture of Cu metal, Cu{sub 2}O and CuO after reduction in hydrogen at 673 K. In contrast, as expected from theoretical stability considerations, the formation of the hollow NiO structure is reversed upon annealing in hydrogen at 673 K and moreover results in the formation of a Ni-rich silicide structure Ni{sub 3}Si{sub 2}. The discussed systems present a convenient way to tackle and investigate various problems in nanotechnology or catalysis, including phase transformations, establishing structure/activity relationships or monitoring intermetallic particles, starting from well-defined and simple models. - Highlights: • Preparation of epitaxial Cu/Cu{sub 2}O and Ni/NiO composite nanoparticles on NaCl(001). • Distinct Ni/NiO particle morphologies. • Formation of well-shaped CuO and NiO particles upon oxidation. • Reversal of Kirkendall-NiO-state upon reduction/annealing in hydrogen.

  4. Well-Defined Cyclic Triblock Terpolymers: A Missing Piece of the Morphology Puzzle

    KAUST Repository

    Polymeropoulos, George


    Two well-defined cyclic triblock terpolymers, missing pieces of the terpolymer morphology puzzle, consisting of poly(isoprene), polystyrene, and poly(2-vinylpyridine), were synthesized by combining the Glaser coupling reaction with anionic polymerization. An α,ω-dihydroxy linear triblock terpolymer (OH-PI1,4-b-PS-b-P2VP-OH) was first synthesized followed by transformation of the OH to alkyne groups by esterification with pentynoic acid and cyclization by Glaser coupling. The size exclusion chromatography (SEC) trace of the linear terpolymer precursor was shifted to lower elution time after cyclization, indicating the successful synthesis of the cyclic terpolymer. Additionally, the SEC trace of the cyclic terpolymer produced, after cleavage of the ester groups, shifted again practically to the position corresponding to the linear precursor. The first exploratory results on morphology showed the tremendous influence of the cyclic structure on the morphology of terpolymers. © 2016 American Chemical Society.

  5. Well-defined Cationic Shell Crosslinked Nanoparticles for Efficient Delivery of DNA or Peptide Nucleic Acids (United States)

    Zhang, Ke; Fang, Huafeng; Shen, Gang; Taylor, John-Stephen A.; Wooley, Karen L.


    This mini-review highlights developments that have been made over the past year to advance the construction of well-defined nanoscale objects to serve as devices for cell transfection. Design of the nanoscale objects originated from biomimicry concepts, using histones as the model, to afford cationic shell crosslinked knedel-like (cSCK) nanoparticles. Packaging and delivery of plasmid DNA, oligonucleotides, and peptide nucleic acids were studied by dynamic light scattering, transmission electron microscopy, gel electrophoresis, biological activity assays, RT-PCR measurements, flow cytometry, and confocal fluorescence microscopy. With the demonstration of more efficient cell transfection in vitro than that achieved using commercially-available transfection agents, together with the other features offered by the robust nanostructural framework, work continues toward the application of these cSCKs for in vivo molecular recognition of genetic material, for imaging and therapy targeted specifically to pulmonary injury and disease. PMID:19687218

  6. A Green function approach to graphene-superconductor junctions with well-defined edges

    Energy Technology Data Exchange (ETDEWEB)

    Herrera, William J [Departamento de Fisica, Universidad Nacional de Colombia, Bogota (Colombia); Burset, P; Levy Yeyati, A [Departamento de Fisica Teorica de la Materia Condensada C-V, Facultad de Ciencias, Universidad Autonoma de Madrid, E-28049 Madrid (Spain)


    This work presents a novel approach to describing spectral properties of graphene layers with well-defined edges. We microscopically analyze the boundary problem for the continuous Bogoliubov-de Gennes-Dirac equations and derive the Green functions for normal and superconducting graphene layers. Importing the idea used in tight-binding models of a microscopic hopping that couples different regions, we are able to set up and solve an algebraic Dyson equation describing a graphene-superconductor junction. For this coupled system we analytically derive the Green functions and use them to calculate the local density of states and the spatial variation of the induced pairing correlations in the normal region. Signatures of specular Andreev reflections are identified.

  7. A Green function approach to graphene-superconductor junctions with well-defined edges. (United States)

    Herrera, William J; Burset, P; Levy Yeyati, A


    This work presents a novel approach to describing spectral properties of graphene layers with well-defined edges. We microscopically analyze the boundary problem for the continuous Bogoliubov-de Gennes-Dirac equations and derive the Green functions for normal and superconducting graphene layers. Importing the idea used in tight-binding models of a microscopic hopping that couples different regions, we are able to set up and solve an algebraic Dyson equation describing a graphene-superconductor junction. For this coupled system we analytically derive the Green functions and use them to calculate the local density of states and the spatial variation of the induced pairing correlations in the normal region. Signatures of specular Andreev reflections are identified.

  8. Well-defined porous membranes for robust omniphobic surfaces via microfluidic emulsion templating (United States)

    Zhu, Pingan; Kong, Tiantian; Tang, Xin; Wang, Liqiu


    Durability is a long-standing challenge in designing liquid-repellent surfaces. A high-performance omniphobic surface must robustly repel liquids, while maintaining mechanical/chemical stability. However, liquid repellency and mechanical durability are generally mutually exclusive properties for many omniphobic surfaces--improving one performance inevitably results in decreased performance in another. Here we report well-defined porous membranes for durable omniphobic surfaces inspired by the springtail cuticle. The omniphobicity is shown via an amphiphilic material micro-textured with re-entrant surface morphology; the mechanical durability arises from the interconnected microstructures. The innovative fabrication method--termed microfluidic emulsion templating--is facile, cost-effective, scalable and can precisely engineer the structural topographies. The robust omniphobic surface is expected to open up new avenues for diverse applications due to its mechanical and chemical robustness, transparency, reversible Cassie-Wenzel transition, transferability, flexibility and stretchability.

  9. Well-Defined Silica Supported Aluminum Hydride: Another Step Towards the Utopian Single Site Dream?

    KAUST Repository

    Werghi, Baraa


    Reaction of triisobutylaluminum with SBA15700 at room temperature occurs by two parallel pathways involving either silanol or siloxane bridges. It leads to the formation of a well-defined bipodal [(≡SiO)2Al-CH2CH(CH3)2] 1a, silicon isobutyl [≡Si-CH2CH(CH3)2] 1b and a silicon hydride [≡Si-H] 1c. Their structural identity was characterized by FT-IR and advance solid-state NMR spectroscopies (1H, 13C, 29Si, 27Al and 2D multiple quantum), elemental and gas phase analysis, and DFT calculations. The reaction involves the formation of a highly reactive monopodal intermediate: [≡SiO-Al-[CH2CH(CH3)2]2], with evolution of isobutane. This intermediate undergoes two parallel routes: Transfer of either one isobutyl fragment or of one hydride to an adjacent silicon atom. Both processes occur by opening of a strained siloxane bridge, ≡Si-O-Si≡ but with two different mechanisms, showing that the reality of “single site” catalyst may be an utopia: DFT calculations indicate that isobutyl transfer occurs via a simple metathesis between the Al-isobutyl and O-Si bonds, while hydride transfer occurs via a two steps mechanism, the first one is a ß-H elimination to Al with elimination of isobutene, whereas the second is a metathesis step between the formed Al-H bond and a O-Si bond. Thermal treatment of 1a (at 250 °C) under high vacuum (10-5 mbar) generates Al-H through a ß-H elimination of isobutyl fragment. These supported well-defined Al-H which are highly stable with time, are tetra, penta and octa coordinated as demonstrated by IR and 27Al–1H J-HMQC NMR spectroscopy. All these observations indicate that surfaces atoms around the site of grafting play a considerable role in the reactivity of a single site system.

  10. Malignant transformation of non-neoplastic Barrett's epithelial cells through well-defined genetic manipulations.

    Directory of Open Access Journals (Sweden)

    Xi Zhang


    Full Text Available Human Barrett's cancer cell lines have numerous, poorly-characterized genetic abnormalities and, consequently, those lines have limited utility as models for studying the early molecular events in carcinogenesis. Cell lines with well-defined genetic lesions that recapitulate various stages of neoplastic progression in Barrett's esophagus would be most useful for such studies.To develop such model cell lines, we started with telomerase-immortalized, non-neoplastic Barrett's epithelial (BAR-T cells, which are spontaneously deficient in p16, and proceeded to knock down p53 using RNAi, to activate Ras by introducing oncogenic H-Ras(G12V, or both. BAR-T cells infected with either p53 RNAi or oncogenic H-Ras(G12V alone maintained cell-to-cell contact inhibition and did not exhibit anchorage-independent growth in soft agar. In contrast, the combination of p53 RNAi knockdown with expression of oncogenic H-Ras(G12V transformed the p16-deficient BAR-T cells, as evidenced by their loss of contact inhibition, by their formation of colonies in soft agar, and by their generation of tumors in immunodeficient mice.Through these experiments, we have generated a number of transformed and non-transformed cell lines with well-characterized genetic abnormalities recapitulating various stages of carcinogenesis in Barrett's esophagus. These lines should be useful models for the study of carcinogenesis in Barrett's esophagus, and for testing the efficacy of chemopreventive and chemotherapeutic agents.

  11. Synthesis and Complexation of Well-Defined Labeled Poly(N,N-dimethylaminoethyl methacrylates (PDMAEMA

    Directory of Open Access Journals (Sweden)

    Mark Billing


    Full Text Available We present the synthesis and characterization of well-defined polycationic copolymers containing thiazole dyes in the side chain. Atom transfer radical polymerization (ATRP was used for the copolymerization of 3-azidopropyl methacrylate (AzPMA and N,N-dimethylaminoethyl methacrylate (DMAEMA of different composition. Thiazole-based alkyne-functionalized dyes (e.g., 5-methyl-4-(prop-2-yn-1-yloxy-2-(pyridin-2-ylthiazole, (MPPT were afterwards covalently attached using copper catalyzed azide alkyne cycloadditions (CuAAC reaching contents of up to 9 mol % dye. Subsequent quaternization of the tertiary nitrogen of DMAEMA with strong methylation agents (e.g., methyl iodide led to permanently charged polyelectrolytes. The materials were characterized by size exclusion chromatography, as well as NMR- and UV/VIS-spectroscopy. Particular attention is paid to the spectroscopic properties of the dyes in the side chain upon environmental changes such as pH and salinity. We anticipate the application of such precisely functionalized polyelectrolytes as temperature- and pH-responsive sensors in biomedical applications, e.g., within interpolyelectrolyte complexes. Concerning the latter, first complex formation results are demonstrated.

  12. Synthesis, characterization and self-assembly of well-defined linear heptablock quaterpolymers

    KAUST Repository

    Ntaras, Christos


    Two well-defined heptablock quaterpolymers of the ABCDCBA type [Α: polystyrene (PS), B: poly(butadiene) with ∼90% 1,4-microstructure (PB1,4), C: poly(isoprene) with ∼55% 3,4-microstructure (PI3,4) and D: poly(dimethylsiloxane) (PDMS)] were synthesized by combining anionic polymerization high vacuum techniques and hydrosilylation/chlorosilane chemistry. All intermediates and final products were characterized by size exclusion chromatography, membrane osmometry, and proton nuclear magnetic resonance spectroscopy. Fourier transform infrared spectroscopy was used to further verify the chemical modification reaction of the difunctional PDMS. The self-assembly in bulk of these novel heptablock quarterpolymers, studied by transmission electron microscopy and small angle X-ray scattering, revealed 3-phase 4-layer alternating lamellae morphology of PS, PB1,4, and mixed PI3,4/PDMS domains. Differential scanning calorimetry was used to further confirm the miscibility of PI3,4 and PDMS blocks. It is the first time that PDMS is the central segment in such multiblock polymers (≥3 chemically different blocks). © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016, 54, 1443–1449. © 2016 Wiley Periodicals, Inc.

  13. Comparative Evaluation of the Chemical Stability of 4 Well-Defined Immunoglobulin G1-Fc Glycoforms. (United States)

    Mozziconacci, Olivier; Okbazghi, Solomon; More, Apurva S; Volkin, David B; Tolbert, Thomas; Schöneich, Christian


    As part of a series of articles in this special issue evaluating model IgG1-Fc glycoforms for biosimilarity analysis, 3 well-defined IgG1-Fc glycoforms (high mannose-Fc, Man5-Fc, and N-acetylglucosamine-Fc) and a nonglycosylated Fc protein (N297Q-Fc) were examined in this work to elucidate chemical degradation pathways. The 4 proteins underwent a combination of accelerated thermal stability studies and 4 independent forced degradation studies (UV light, metal-catalyzed oxidation, peroxyl radicals, and hydrogen peroxide) at pH 6.0. Our results highlight chemical degradations at Asn315, Met428, Trp277, and Trp313. A cross-comparison of the different Fc glycoforms, stress conditions, and the observed chemical reactions revealed that both the deamidation of Asn315 and the transformation of Trp277 into glycine hydroperoxide were glycan dependent during incubation for 3 months at 40 °C. Our data will show that different glycans not only affect chemical degradation differently but also do lead to different impurity profiles, which can affect chemical degradation. Copyright © 2016 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

  14. Well-Defined Polyethylene-Based Random, Block, and Bilayered Molecular Cobrushes

    KAUST Repository

    Zhang, Hefeng


    Novel well-defined polyethylene-based random, block, and bilayered molecular cobrushes were synthesized through the macromonomer strategy. Two steps were involved in this approach: (i) synthesis of norbornyl-terminated macromonomers of polyethylene (PE), polycaprolactone (PCL), poly(ethylene oxide) (PEO), and polystyrene (PS), as well as polyethylene-b-polycaprolactone (PE-b-PCL), by esterification of the hydroxyl-terminated precursors (PE, PCL, PEO, PS, and PE-b-PCL) with 5-norbornene-2-carboxylic acid and (ii) ring-opening metathesis (co)polymerization of the resulting macromonomers to afford the PE-based molecular cobrushes. The PE-macromonomers were synthesized by polyhomologation of dimethylsulfoxonium methylide, while the others by anionic polymerization. Proton nuclear magnetic resonance spectroscopy (1H NMR) and high-temperature gel permeation chromatography (HT-GPC) were used to imprint the molecular characteristics of all macromonomers and molecular brushes and differential scanning calorimetry (DSC) for the thermal properties. The bilayered molecular cobrushes of P(PE-b-PCL) adopt a wormlike morphology on silica wafer as visualized by atomic force microscopy (AFM). © 2015 American Chemical Society.

  15. Co-aggregation of two anionic azo dyestuffs at a well-defined stoichiometry. (United States)

    Michels, Rolf; Sinemus, Thomas; Hoffmann, Jan; Brutschy, Bernhard; Huber, Klaus


    The present work investigates the formation of well-defined heteroaggregates from a binary mixture of a red and a yellow azo-dyestuff in the presence of Mg(2+) ions. Combined static and dynamic light scattering together with laser induced liquid bead ion desorption mass spectrometry (LILBID-MS) has been applied to characterize the states of the pure red dye and the pure yellow dye as well as of their mixture in aqueous solution without Mg(2+). These experiments indicated that a structural reorganization on a molecular scale takes place as soon as the two dyes are combined. Solutions of the combined red and yellow dye contain micelle-like mixed entities with a size of a few tenths of nanometers. Upon the addition of Mg(2+), these micelles vanish in favor of elongated heteroaggregates, which grow by a stepwise addition of smaller building units. As unraveled by UV/vis spectroscopy, the heteroaggregates that are formed from the red and yellow azo dye in the presence of Mg(2+) obey a stoichiometric ratio of the two components of 1:1. A new multiangle scattering instrument allowed us for the first time to follow this aggregation process at the stoichiometric ratio by time-resolved combined static and dynamic light scattering, thereby providing further aspects of the worm-like nature of the growing heteroaggregates.

  16. Catalysis by Design: Well-Defined Single-Site Heterogeneous Catalysts. (United States)

    Pelletier, Jérémie D A; Basset, Jean-Marie


    Heterogeneous catalysis, a field important industrially and scientifically, is increasingly seeking and refining strategies to render itself more predictable. The main issue is due to the nature and the population of catalytically active sites. Their number is generally low to very low, their "acid strengths" or " redox properties" are not homogeneous, and the material may display related yet inactive sites on the same material. In many heterogeneous catalysts, the discovery of a structure-activity reationship is at best challenging. One possible solution is to generate single-site catalysts in which most, if not all, of the sites are structurally identical. Within this context and using the right tools, the catalyst structure can be designed and well-defined, to reach a molecular understanding. It is then feasible to understand the structure-activity relationship and to develop predictable heterogeneous catalysis. Single-site well-defined heterogeneous catalysts can be prepared using concepts and tools of surface organometallic chemistry (SOMC). This approach operates by reacting organometallic compounds with surfaces of highly divided oxides (or of metal nanoparticles). This strategy has a solid track record to reveal structure-activity relationship to the extent that it is becoming now quite predictable. Almost all elements of the periodical table have been grafted on surfaces of oxides (from simple oxides such as silica or alumina to more sophisticated materials regarding composition or porosity). Considering catalytic hydrocarbon transformations, heterogeneous catalysis outcome may now be predicted based on existing mechanistic proposals and the rules of molecular chemistry (organometallic, organic) associated with some concepts of surface sciences. A thorough characterization of the grafted metal centers must be carried out using tools spanning from molecular organometallic or surface chemistry. By selection of the metal, its ligand set, and the support taken

  17. Catalysis by Design: Well-Defined Single-Site Heterogeneous Catalysts

    KAUST Repository

    Pelletier, Jeremie


    ConspectusHeterogeneous catalysis, a field important industrially and scientifically, is increasingly seeking and refining strategies to render itself more predictable. The main issue is due to the nature and the population of catalytically active sites. Their number is generally low to very low, their "acid strengths" or " redox properties" are not homogeneous, and the material may display related yet inactive sites on the same material. In many heterogeneous catalysts, the discovery of a structure-activity reationship is at best challenging. One possible solution is to generate single-site catalysts in which most, if not all, of the sites are structurally identical. Within this context and using the right tools, the catalyst structure can be designed and well-defined, to reach a molecular understanding. It is then feasible to understand the structure-activity relationship and to develop predictable heterogeneous catalysis. Single-site well-defined heterogeneous catalysts can be prepared using concepts and tools of surface organometallic chemistry (SOMC). This approach operates by reacting organometallic compounds with surfaces of highly divided oxides (or of metal nanoparticles). This strategy has a solid track record to reveal structure-activity relationship to the extent that it is becoming now quite predictable. Almost all elements of the periodical table have been grafted on surfaces of oxides (from simple oxides such as silica or alumina to more sophisticated materials regarding composition or porosity).Considering catalytic hydrocarbon transformations, heterogeneous catalysis outcome may now be predicted based on existing mechanistic proposals and the rules of molecular chemistry (organometallic, organic) associated with some concepts of surface sciences. A thorough characterization of the grafted metal centers must be carried out using tools spanning from molecular organometallic or surface chemistry. By selection of the metal, its ligand set, and the

  18. Sorption and diffusion of phenols onto well-defined ordered nanoporous monolithic silicas. (United States)

    El-Safty, S A


    The sorption of phenol, and o-, m-, and p-aminophenol (o-, m-, and p-AP) onto highly ordered mesoporous silicas (HOM) with cubic Im3m (HOM-1), hexagonal H(I) (HOM-2), 3-D hexagonal p6(3)/mmc (HOM-3), cubic Ia3d (HOM-5), lamellar L( infinity ) (HOM-6), and solid phase S (HOM-8) materials has been investigated kinetically. Nanostructured silica molecular sieves have been prepared at 25 and 60 degrees C with lyotropic liquid-crystalline phases of the nonionic surfactant (Brij 76) that was used as a structure-directing agent. Such nanostructured silicas have been studied by 29Si nuclear magnetic resonance (29Si NMR), powder X-ray diffraction (XRD), the Brunauer-Emmett-Teller (BET) method for nitrogen adsorption and surface area measurements, and transmission electron microscopy (TEM) techniques after synthesis and sorption. It was found that all materials exhibit well-defined long-range porous architectures without significant loss of the ordered texture during phenol sorption. The kinetics of phenol sorption has been studied spectrophotometrically at different temperatures (25-40 degrees C; +/-0.1 range). The sorption rate is zero order in all phenols sorbed, and increases directly in the pattern P >m-AP > o-AP > p-AP, which reflects the mobility of the phenol compounds on the particle pores. The isothermal sorption and the kinetic parameters were discussed and it was established that a diffusion-controlled process characterizes phenol sorption. Furthermore, the mechanism of phenol sorption was deduced to be predominantly particle diffusion. The diffusion coefficients were determined using Fick's equation. The trend of diffusion of all phenols onto nanoporous silica was HOM-8 > HOM-2 > HOM-6 > HOM-5 > HOM-1 > HOM-3, reflecting the effect of the uniform pore size distribution and the internal surface area of the nanostructured silicas on the diffusion process.

  19. A Well-Defined Osmium-Cupin Complex: Hyperstable Artificial Osmium Peroxygenase. (United States)

    Fujieda, Nobutaka; Nakano, Takumi; Taniguchi, Yuki; Ichihashi, Haruna; Sugimoto, Hideki; Morimoto, Yuma; Nishikawa, Yosuke; Kurisu, Genji; Itoh, Shinobu


    Thermally stable TM1459 cupin superfamily protein from Thermotoga maritima was repurposed as an osmium (Os) peroxygenase by metal-substitution strategy employing the metal-binding promiscuity. This novel artificial metalloenzyme bears a datively bound Os ion supported by the 4-histidine motif. The well-defined Os center is responsible for not only the catalytic activity but also the thermodynamic stability of the protein folding, leading to the robust biocatalyst (Tm ≈ 120 °C). The spectroscopic analysis and atomic resolution X-ray crystal structures of Os-bound TM1459 revealed two types of donor sets to Os center with octahedral coordination geometry. One includes trans-dioxide, OH, and mer-three histidine imidazoles (O3N3 donor set), whereas another one has four histidine imidazoles plus OH and water molecule in a cis position (O2N4 donor set). The Os-bound TM1459 having the latter donor set (O2N4 donor set) was evaluated as a peroxygenase, which was able to catalyze cis-dihydroxylation of several alkenes efficiently. With the low catalyst loading (0.01% mol), up to 9100 turnover number was achieved for the dihydroxylation of 2-methoxy-6-vinyl-naphthalene (50 mM) using an equivalent of H2O2 as oxidant at 70 °C for 12 h. When octene isomers were dihydroxylated in a preparative scale for 5 h (2% mol cat.), the terminal alkene octene isomers was converted to the corresponding diols in a higher yield as compared with the internal alkenes. The result indicates that the protein scaffold can control the regioselectivity by the steric hindrance. This protein scaffold enhances the efficiency of the reaction by suppressing disproportionation of H2O2 on Os reaction center. Moreover, upon a simple site-directed mutagenesis, the catalytic activity was enhanced by about 3-fold, indicating that Os-TM1459 is evolvable nascent osmium peroxygenase.

  20. Physics and chemistry on well-defined semiconductor and oxide surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Peijun


    High resolution electron energy loss spectroscopy (HREELS) and other surface spectroscopic techniques have been employed to investigate the following two classes of surface/interface phenomena on well-defined semiconductor and oxide surfaces: (i) the fundamental physical and chemical processes involved in gas-solid interaction on silicon single crystal surfaces, and (ii) the physical and chemical properties of metal-oxide interfaces. The particular systems reported in this dissertation are: NH{sub 3}, PH{sub 3} and B{sub 10}H{sub 14} on Si(111)-(7 x 7); NH{sub 3} on Si(100)-(2 x 1); atomic H on Si(111)-(7 x 7) and boron-modified Si(111); Al on Al{sub 2}O{sub 3} and Sn on SiO{sub 2}. On silicon surfaces, the surface dangling bonds function as the primary adsorption sites where surface chemical processes take place. The unambiguous identification of surface species by vibrational spectroscopy allow the elementary steps involved in these surface chemical processes to be followed on a molecular level. For adsorbate such as NH{sub 3} and PH{sub 3}, the nature of the initial low temperature (100-300 K) adsorption is found to be dissociative, while that for B{sub 10}H{sub 14} is non-dissociative. This has been deduced based upon the presence (or absence) of specific characteristic vibrational mode(s) on surface. By following the evolution of surface species as a function of temperature, the elementary steps leading to silicon nitride thin film growth and doping of silicon are elucidated. In the case of NH{sub 3} on Si(111)-(7 x7) and Si(100)-(2 x 1), a detailed understanding on the role of substrate surface structure is controlling the surface reactivity has been gained on the basis of a Si adatom backbond-strain relief mechanism on the Si(111)-(7 x 7). The electronic modification to Si(111) surface by subsurface boron doping has been shown to quench its surface chemistry, even for the most aggressive atomic H.

  1. Well-defined silica supported bipodal molybdenum oxo alkyl complexes: a model of the active sites of industrial olefin metathesis catalysts

    KAUST Repository

    Merle, Nicolas


    A well-defined, silica-supported molybdenum oxo alkyl species, ([triple bond, length as m-dash]SiO-)2Mo([double bond, length as m-dash]O)(CH2tBu)2, was prepared by the selective grafting of Mo([double bond, length as m-dash]O)(CH2tBu)3Cl onto a silica partially dehydroxylated at 200 °C using a rigorous surface organometallic chemistry approach. The immobilized bipodal surface species, partly resembling the active species of industrial MoO3/SiO2 olefin metathesis catalysts, exhibited excellent functional group tolerance in conjunction with its high activity in homocoupling, self and ring closing olefin metathesis.

  2. Well-defined silica supported bipodal molybdenum oxo alkyl complexes: a model of the active sites of industrial olefin metathesis catalysts. (United States)

    Merle, Nicolas; Le Quéméner, Frédéric; Barman, Samir; Samantaray, Manoja K; Szeto, Kai C; De Mallmann, Aimery; Taoufik, Mostafa; Basset, Jean-Marie


    A well-defined, silica-supported molybdenum oxo alkyl species, ([triple bond, length as m-dash]SiO-)2Mo([double bond, length as m-dash]O)(CH2(t)Bu)2, was prepared by the selective grafting of Mo([double bond, length as m-dash]O)(CH2(t)Bu)3Cl onto a silica partially dehydroxylated at 200 °C using a rigorous surface organometallic chemistry approach. The immobilized bipodal surface species, partly resembling the active species of industrial MoO3/SiO2 olefin metathesis catalysts, exhibited excellent functional group tolerance in conjunction with its high activity in homocoupling, self and ring closing olefin metathesis.

  3. Structure of branching enzyme- and amylomaltase modified starch produced from well-defined amylose to amylopectin substrates

    DEFF Research Database (Denmark)

    Sorndecha, Waraporn; Sagnelli, Domenico; Meier, Sebastian


    constituent in starch and the effect of amylose on enzyme catalysis was investigated using amylose-only barley starch (AO) and waxy maize starch (WX) in well-defined ratios. All products were analysed for amylopectin chain length distribution, α-1,6 glucosidic linkages content, molar mass distribution...... and digestibility by using rat intestinal α-glucosidases. For each enzyme treatment series, increased AO content resulted in a higher rate of α-1,6 glucosidic linkage formation but as an effect of the very low initial branching of the AO, the final content of α-1,6 glucosidic linkages was slightly lower as compared...

  4. Efficient hydrogen liberation from formic acid catalyzed by a well-defined iron pincer complex under mild conditions. (United States)

    Zell, Thomas; Butschke, Burkhard; Ben-David, Yehoshoa; Milstein, David


    Hydrogen liberation: An attractive approach to reversible hydrogen storage applications is based on the decomposition of formic acid. The efficient and selective hydrogen liberation from formic acid is catalyzed by an iron pincer complex in the presence of trialkylamine. Turnover frequencies up to 836 h⁻¹ and turnover numbers up to 100,000 were achieved at 40 °C. A mechanism including well-defined intermediates is suggested on the basis of experimental and computational data. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Physical degradation of proteins in well-defined fluid flows studied within a four-roll apparatus. (United States)

    Simon, S; Krause, H J; Weber, C; Peukert, W


    In most applications of biotechnology and downstream processing proteins are exposed to fluid stresses in various flow configurations which often lead to the formation of unwanted protein aggregates. In this paper we present physical degradation experiments for proteins under well-defined flow conditions in a four-roll apparatus. The flow field was characterized numerically by computational fluid dynamics (CFD) and experimentally by particle image velocimetry (PIV). The local shear strain rate as well as the local shear and elongation rate was used to characterize the hydrodynamic stress environment acting on the proteins. Lysozyme was used as a model protein and subjected to well-defined fluid stresses in high and low stress environment. By using in situ turbidity measurements during stressing the aggregate formation was monitored directly in the fluid flow. An increase in absorbance at 350 nm was attributed to a higher content of visible particles (>1 µm). In addition to lysozyme, the formation of aggregates was confirmed for two larger proteins (bovine serum albumin and alcohol dehydrogenase). Thus, the presented experimental setup is a helpful tool to monitor flow-induced protein aggregation with high reproducibility. For instance, screening experiments for formulation development of biopharmaceuticals for fill and finish operations can be performed in the lab-scale in a short time-period if the stress distributions in the application are transferred and applied in the four-roll mill. Copyright © 2011 Wiley Periodicals, Inc.

  6. Synthesis and evaluation of a well-defined HPMA copolymer-dexamethasone conjugate for effective treatment of rheumatoid arthritis. (United States)

    Liu, Xin-Ming; Quan, Ling-Dong; Tian, Jun; Alnouti, Yazen; Fu, Kai; Thiele, Geoffrey M; Wang, Dong


    To develop a pH-sensitive dexamethasone (Dex)-containing N-(2-hydroxypropyl)methacrylamide (HPMA) copolymer conjugate with well-defined structure for the improved treatment of rheumatoid arthritis (RA). A new pH-sensitive Dex-containing monomer (MA-Gly-Gly-NHN=Dex) was synthesized and copolymerized with HPMA using reversible addition-fragmentation transfer (RAFT) polymerization. The structure of the resulting HPMA copolymer-Dex conjugate (P-Dex) was analyzed and its therapeutic efficacy was evaluated on adjuvant-induced arthritis (AIA) rats. P-Dex was synthesized with controllable molecular weight and polydispersity index (PDI). The Dex content can be controlled by the feed-in ratio of MA-Gly-Gly-NHN=Dex. The P-Dex used for in vitro and in vivo evaluation has a average molecular weight (M (w)) of 34 kDa and a PDI of 1.34. The in vitro drug-release studies showed that the Dex release from the conjugate was triggered by low pH. Clinical measurements, endpoint bone mineral density (BMD) test and histology grading from the in vivo evaluation all suggest that newly synthesized P-Dex has strong and long-lasting anti-inflammatory and joint protection effects. A HPMA copolymer-dexamethasone conjugate with a well-defined structure has been synthesized and proved to be an effective anti-arthritis therapy. It may have a unique clinical application in the treatment of rheumatoid arthritis.

  7. In Situ SIMS and IR Spectroscopy of Well-Defined Surfaces Prepared by Soft Landing of Mass-Selected Ions

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Grant E.; Gunaratne, Kalupathirannehelage Don D.; Laskin, Julia


    Soft landing of mass-selected ions onto surfaces is a powerful approach for the highly-controlled preparation of materials that are inaccessible using conventional synthesis techniques. Coupling soft landing with in situ characterization using secondary ion mass spectrometry (SIMS) and infrared reflection absorption spectroscopy (IRRAS) enables analysis of well-defined surfaces under clean vacuum conditions. The capabilities of three soft-landing instruments constructed in our laboratory are illustrated for the representative system of surface-bound organometallics prepared by soft landing of mass-selected ruthenium tris(bipyridine) dications, [Ru(bpy)3]2+, onto carboxylic acid terminated self-assembled monolayer surfaces on gold (COOH-SAMs). In situ time-of-flight (TOF)-SIMS provides insight into the reactivity of the soft-landed ions. In addition, the kinetics of charge reduction, neutralization and desorption occurring on the COOH-SAM both during and after ion soft landing are studied using in situ Fourier transform ion cyclotron resonance (FT-ICR)-SIMS measurements. In situ IRRAS experiments provide insight into how the structure of organic ligands surrounding metal centers is perturbed through immobilization of organometallic ions on COOH-SAM surfaces by soft landing. Collectively, the three instruments provide complementary information about the chemical composition, reactivity and structure of well-defined species supported on surfaces.

  8. Well-Defined Molybdenum Oxo Alkyl Complex Supported on Silica by Surface Organometallic Chemistry: A Highly Active Olefin Metathesis Precatalyst

    KAUST Repository

    Merle, Nicolas


    The well-defined silica-supported molybdenum oxo alkyl species (SiO−)MoO(CH Bu) was selectively prepared by grafting of MoO(CH Bu)Cl onto partially dehydroxylated silica (silica) using the surface organometallic chemistry approach. This surface species was fully characterized by elemental analysis and DRIFT, solid-state NMR, and EXAFS spectroscopy. This new material is related to the active species of industrial supported MoO/SiO olefin metathesis catalysts. It displays very high activity in propene self-metathesis at mild (turnover number = 90 000 after 25 h). Remarkably, its catalytic performance outpaces those of the parent imido derivative and its tungsten oxo analogue.

  9. Preparation of well-defined erythromycin imprinted non-woven fabrics via radiation-induced RAFT-mediated grafting (United States)

    Söylemez, Meshude Akbulut; Barsbay, Murat; Güven, Olgun


    Radiation-induced RAFT polymerization technique was applied to synthesize well-defined molecularly imprinted polymers (MIPs) of erythromycin (ERY). Methacrylic acid (MAA) was grafted onto porous polyethylene (PE)/polypropylene (PP) nonwoven fabrics, under γ-irradiation by employing 2-pheny-2-propyl benzodithioate as the RAFT agent and ethylene glycol dimethacrylate (EGDMA) as the crosslinker. MAA/erythromycin ratios of 2/1, 4/1, 6/1 were tested to optimize the synthesis of MIPs. The highest binding capacity was encountered at a MAA/ERY ratio of 4/1. Non-imprinted polymers (NIPs) were also synthesized in the absence of ERY. The MIPs synthesized by RAFT method presented a better binding capacity compared to those prepared by conventional method where no RAFT agent was employed.

  10. Well-Defined Molybdenum Oxo Alkyl Complex Supported on Silica by Surface Organometallic Chemistry: A Highly Active Olefin Metathesis Precatalyst. (United States)

    Merle, Nicolas; Le Quéméner, Frédéric; Bouhoute, Yassine; Szeto, Kai C; De Mallmann, Aimery; Barman, Samir; Samantaray, Manoja K; Delevoye, Laurent; Gauvin, Régis M; Taoufik, Mostafa; Basset, Jean-Marie


    The well-defined silica-supported molybdenum oxo alkyl species (≡SiO-)MoO(CH2tBu)3 was selectively prepared by grafting of MoO(CH2tBu)3Cl onto partially dehydroxylated silica (silica700) using the surface organometallic chemistry approach. This surface species was fully characterized by elemental analysis and DRIFT, solid-state NMR, and EXAFS spectroscopy. This new material is related to the active species of industrial supported MoO3/SiO2 olefin metathesis catalysts. It displays very high activity in propene self-metathesis at mild (turnover number = 90 000 after 25 h). Remarkably, its catalytic performance outpaces those of the parent imido derivative and its tungsten oxo analogue.

  11. Acyclic Diene Metathesis (ADMET Polymerization for Precise Synthesis of Defect-Free Conjugated Polymers with Well-Defined Chain Ends

    Directory of Open Access Journals (Sweden)

    Tahmina Haque


    Full Text Available This accounts introduces unique characteristics by adopting the acyclic diene metathesis (ADMET polymerization for synthesis of conjugated polymers, poly(arylene vinylenes, known as promising molecular electronics. The method is more suitable than the other methods in terms of atom efficiency affording defect-free, stereo-regular (exclusive trans polymers with well-defined chain ends; the resultant polymers possess better property than those prepared by the conventional methods. The chain ends (vinyl group in the resultant polymer prepared by ruthenium-carbene catalyst(s can be modified by treating with molybdenum-alkylidene complex (olefin metathesis followed by addition of various aldehyde (Wittig type cleavage, affording the end-functionalized polymers exclusively. An introduction of initiating fragment, the other conjugated segment, and one-pot synthesis of end-functionalized block copolymers, star shape polymers can be achieved by adopting this methodology.

  12. Stable aqueous based Cu nanoparticle ink for printing well-defined highly conductive features on a plastic substrate. (United States)

    Jeong, Sunho; Song, Hae Chun; Lee, Won Woo; Lee, Sun Sook; Choi, Youngmin; Son, Wonil; Kim, Eui Duk; Paik, Choon Hoon; Oh, Seok Heon; Ryu, Beyong-Hwan


    With the aim of inkjet printing highly conductive and well-defined Cu features on plastic substrates, aqueous based Cu ink is prepared for the first time using water-soluble Cu nanoparticles with a very thin surface oxide layer. Owing to the specific properties, high surface tension and low boiling point, of water, the aqueous based Cu ink endows a variety of advantages over conventional Cu inks based on organic solvents in printing narrow conductive patterns without irregular morphologies. It is demonstrated how the design of aqueous based ink affects the basic properties of printed conductive features such as surface morphology, microstructure, conductivity, and line width. The long-term stability of aqueous based Cu ink against oxidation is analyzed through an X-ray photoelectron spectroscopy (XPS) based investigation on the evolution of the surface oxide layer in the aqueous based ink.

  13. Self-assembly behavior of well-defined polymethylene-block-poly(ethylene glycol) copolymers in aqueous solution

    KAUST Repository

    Alkayal, Nazeeha


    A series of well-defined amphiphilic polymethylene-b-poly(ethylene glycol) (PM-b-PEG) diblock copolymers, with different hydrophobic chain length, were synthesized by combining Diels-Alder reaction with polyhomologation. The successful synthetic procedure was confirmed by size-exclusion chromatography (SEC) and 1H NMR spectroscopy. These block copolymers self-assembled into spherical micelles in aqueous solutions and exhibit low critical micelle concentration (CMC) of 2–4 mg/mL, as determined by fluorescence spectroscopy using pyrene as a probe. Measurements of the micelle hydrodynamic diameters, performed by dynamic light scattering (DLS), cryo-transmission electron microscopy (cryo-TEM) and atomic force microscopy (AFM), revealed a direct dependence of the micelle size from the polymethylene block length.

  14. Synthesis of Well-Defined Polybenzamide-block-Polystyrene by Combination of Chain-Growth Condensation Polymerization and RAFT Polymerization. (United States)

    Masukawa, Tomohiro; Yokoyama, Akihiro; Yokozawa, Tsutomu


    Well-defined diblock copolymers composed of poly(N-octylbenzamide) and polystyrene were synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization of styrene with a polyamide chain transfer agent (CTA) prepared via chain-growth condensation polymerization. Synthesis of a dithioester-type macro-CTA possessing the polyamide segment as an activating group was unsatisfactory due to side reactions and incomplete introduction of the benzyl dithiocarbonyl unit. On the other hand, a dithiobenzoate-CTA containing poly(N-octylbenzamide) as a radical leaving group was easily synthesized, and the RAFT polymerization of styrene with this CTA afforded poly(N-octylbenzamide)-block-polystyrene with controlled molecular weight and narrow polydispersity. Copyright © 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Well-defined and high resolution Pt nanowire arrays for a high performance hydrogen sensor by a surface scattering phenomenon. (United States)

    Yoo, Hae-Wook; Cho, Soo-Yeon; Jeon, Hwan-Jin; Jung, Hee-Tae


    Developing hydrogen (H2) sensors with a high sensitivity, rapid response, long-term stability, and high throughput is one of the critical issues in energy and environmental technology [Hübert et al. Sens. Actuators, B 2011, 157, 329]. To date, H2 sensors have been mainly developed using palladium (Pd) as the channel material because of its high selectivity and strong affinity to the H2 molecule [(Xu et al. Appl. Phys. Lett. 2005, 86, 203104), (Offermans et al. Appl. Phys. Lett. 2009, 94, 223110), (Yang et al. Nano Lett. 2009, 9, 2177), (Yang et al. ACS Nano 2010, 4, 5233), and (Zou et al. Chem. Commun. 2012, 48, 1033)]. Despite significant progress in this area, Pd based H2 sensors suffer from fractures on their structure due to hydrogen adsorption induced volumetric swelling during the α → β phase transition, leading to poor long-term stability and reliability [(Favier et al. Science 2001, 293, 2227), (Walter et al. Microelectron. Eng. 2002, 61–62, 555), and (Walter et al. Anal. Chem. 2002, 74, 1546)]. In this study, we developed a platinum (Pt) nanostructure based H2 sensor that avoids the stability limitations of Pd based sensors. This sensor exhibited an excellent sensing performance, low limit of detection (LOD, 1 ppm), reproducibility, and good recovery behavior at room temperature. This Pt based H2 sensor relies on a highly periodic, small cross sectional dimension (10–40 nm) and a well-defined configuration of Pt nanowire arrays over a large area. The resistance of the Pt nanowire arrays significantly decreased upon exposure to H2 due to reduced electron scattering in the cross section of the hydrogen adsorbed Pt nanowires, as compared to the oxygen terminated original state. Therefore, these well-defined Pt nanowire arrays prepared using advanced lithographic techniques can facilitate the production of high performance H2 sensors.

  16. Well-defined block copolymers for gene delivery to dendritic cells: probing the effect of polycation chain-length. (United States)

    Tang, Rupei; Palumbo, R Noelle; Nagarajan, Lakshmi; Krogstad, Emily; Wang, Chun


    The development of safe and efficient polymer carriers for DNA vaccine delivery requires mechanistic understanding of structure-function relationship of the polymer carriers and their interaction with antigen-presenting cells. Here we have synthesized a series of diblock copolymers with well-defined chain-length using atom transfer radical polymerization and characterized the influence of polycation chain-length on the physico-chemical properties of the polymer/DNA complexes as well as the interaction with dendritic cells. The copolymers consist of a hydrophilic poly(ethylene glycol) block and a cationic poly(aminoethyl methacrylate) (PAEM) block. The average degree of polymerization (DP) of the PAEM block was varied among 19, 39, and 75, with nearly uniform distribution. With increasing PAEM chain-length, polyplexes formed by the diblock copolymers and plasmid DNA had smaller average particle size and showed higher stability against electrostatic destabilization by salt and heparin. The polymers were not toxic to mouse dendritic cells (DCs) and only displayed chain-length-dependent toxicity at a high concentration (1mg/mL). In vitro gene transfection efficiency and polyplex uptake in DCs were also found to correlate with chain-length of the PAEM block with the longer polymer chain favoring transfection and cellular uptake. The polyplexes induced a modest up-regulation of surface markers for DC maturation that was not significantly dependent on PAEM chain-length. Finally, the polyplex prepared from the longest PAEM block (DP of 75) achieved an average of 20% enhancement over non-condensed anionic dextran in terms of uptake by DCs in the draining lymph nodes 24h after subcutaneous injection into mice. Insights gained from studying such structurally well-defined polymer carriers and their interaction with dendritic cells may contribute to improved design of practically useful DNA vaccine delivery systems. Copyright 2009 Elsevier B.V. All rights reserved.

  17. Understanding the Hydro-metathesis Reaction of 1-decene by Using Well-defined Silica Supported W, Mo, Ta Carbene/Carbyne Complexes

    KAUST Repository

    Saidi, Aya


    Direct conversion of 1-decene to petroleum range alkanes was obtained using hydro-metathesis reaction. To understand this reaction we employed three different well-defined single site catalysts precursors; [(≡Si-O-)W(CH3)5] 1, [(≡Si-O-)Mo(≡CtBu)(CH2tBu)2] 2 and [(≡Si-O)Ta(=CHtBu)(CH2tBu)2] 3. We witnessed that in our conditions olefin metathesis/isomerization of 1-decene occurs much faster followed by reduction of the newly formed olefins rather than reduction of the 1-decene to decane, followed by metathesis of decane. We found that Mo-based catalyst favors 2+2 cycloaddition of 1-decene forming metallocarbene, followed by reduction of the newly formed olefins to alkanes. However, in the case of W and Ta-based catalysts, a rapid isomerization (migration) of the double bond followed by olefin metathesis and reduction of the newly formed olefins were observed. We witnessed that silica supported W catalyst precursor 1 and Mo catalyst precursor 2 are better catalysts for hydro-metathesis reaction with TONs of 818 and 808 than Ta-based catalyst 3 (TON of 334). This comparison of the catalysts provides us a better understanding that, if a catalyst is efficient in olefin metathesis reaction it would be a better catalyst for hydro-metathesis reaction.

  18. Well-defined Polymethylene-Based Co/Terpolymers by Combining Anthracene/Maleimide Diels-Alder Reaction with Polyhomologation

    KAUST Repository

    Hadjichristidis, Nikolaos


    A novel strategy towards well-defined polymethylene-based co/terpolymers, by combining anthracene/maleimide Diels-Alder reaction with polyhomologation, is presented. For the synthesis of diblock copolymers the following approach was applied: a) synthesis of α-anthracene-ω-hydroxy- polymethylene by polyhomologation using tri (9-anthracene-methyl propyl ether) borane as initiator, b) synthesis of furan-protected-maleimide-terminated poly (ε-caprolactone) or polyethylene glycol and c). Diels-Alder reaction between the anthracene and maleimide-terminated polymers. In the case of triblock terpolymers the α-anthracene-ω-hydroxy-polymethylene was used as macroinitiator for the ring-opening polymerization of D, L-lactide to afford an anthracene-terminated PM-b-PLA copolymer, followed by Diels-Alder reaction with furan-protected maleimide-terminated poly (ε-caprolactone) or polyethylene glycol to give the triblock terpolymers. All intermediate and final products were characterized by SEC, 1H NMR, UV-VIS spectroscopy and DSC.

  19. Well-defined triblock copolymers of polyethylene with polycaprolactone or polystyrene using a novel difunctional polyhomologation initiator

    KAUST Repository

    Hadjichristidis, Nikolaos


    α,ω-Dihydroxy polyethylene was synthesized by polyhomologation of dimethylsulfoxonium methylide with 9-thexyl-9-BBN (9-BNN: 9-Borabicyclo[3.3.1]nonane), a novel difunctional initiator produced from 9-BBN and 2,3-dimethylbut-2-ene, with two active and one blocked sites, followed by hydrolysis/oxidation. The terminal hydroxy groups were either used directly as initiators, in the presence of 1-tert-butyl-2,2,4,4,4-pentakis(dimethylamino)-2λ5,4λ5-catenadi(phosphazene) (t-BuP2), for the ring opening polymerization of ɛ-caprolactone to afford polycaprolactone-b-polyethylene-b-polycaprolactone (PCL-b-PE-b-PCL) or after transformation to atom transfer radical polymerization initiating sites, for the polymerization of styrene to produce polystyrene-b-polyethylene-b-polystyrene (PSt-b-PE-b-PSt) triblock copolymers. Molecular characterization by 11B, 13C and 1H NMR as well as FTIR, and high temperature GPC (HT-GPC) confirmed the well-defined nature of the synthesized new difunctional initiator and triblock copolymers. Differential scanning calorimetry was used to determine the melting points of PE and PCL.

  20. A New Synthetic Route to Microporous Silica with Well-Defined Pores by Replication of a Metal-Organic Framework. (United States)

    Kondo, Atsushi; Hall, Anthony Shoji; Mallouk, Thomas E; Maeda, Kazuyuki


    Microporous amorphous hydrophobic silica materials with well-defined pores were synthesized by replication of the metal-organic framework (MOF) [Cu3 (1,3,5-benzenetricarboxylate)2 ] (HKUST-1). The silica replicas were obtained by using tetramethoxysilane or tetraethoxysilane as silica precursors and have a micro-meso binary pore system. The BET surface area, the micropore volume, and the mesopore volume of the silica replica, obtained by means of hydrothermal treatment at 423 K with tetraethoxysilane, are 620 m(2) g(-1) , 0.18 mL g(-1) , and 0.55 mL g(-1) , respectively. Interestingly, the silica has micropores with a pore size of 0.55 nm that corresponds to the pore-wall thickness of the template MOF. The silica replica is hydrophobic, as confirmed by adsorption analyses, although the replica has a certain amount of silanol groups. This hydrophobicity is due to the unique condensation environment of the silica precursors in the template MOF. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Syntheses and Post-Polymerization Modifications of Well-Defined Styrenic Polymers Containing Three-Membered Heterocyclic Functionalities (United States)

    McLeod, David Charles

    Macromolecules that contain electrophilic moieties, such as benzyl halides, activated esters, and epoxides, will readily undergo efficient nucleophilic substitution reactions with a wide variety of compounds under mild conditions, and are therefore ideally suited to act as "universal" precursors to functional materials. Epoxide-containing polymers derived from the radical polymerization of commercially-available glycidyl methacrylate are often employed in this role; however, methacrylic polymers suffer from certain limitations as a result of the incorporated ester groups, which are not stabile in the presence of strong nucleophiles, acids, bases, or esterase enzymes. Styrenic polymers that do not contain labile carbonyl moieties are usually the precursors of choice when high chemical stability is desired in the end product, but the production of functional materials from epoxide-containing styrenic polymers is relatively unexplored. In this dissertation, improved methods were developed for synthesizing 4-vinylphenyloxirane (4VPO) and 4-vinylphenyl glycidyl ether (4VPGE), two of the better-known epoxide-containing styrenic monomers, in high-yield and purity. Well-defined, epoxide-containing styrenic polymers with targeted molecular weights, narrow molecular weight distributions, and controlled architectures (specifically, linear and star-shaped homopolymers, as well as linear block copolymers with styrene) were produced from 4VPO and 4VPGE for the first time using reversible-deactivation radical polymerization techniques, such as low-catalyst-concentration atom transfer radical polymerization (LCC ATRP) and reversible addition-fragmentation chain-transfer (RAFT) polymerization. The robust nature and utility of poly4VPO and poly4VPGE were then demonstrated by the efficient, ring-opening modification of the pendant epoxide groups with a structurally- and functionally-diverse array of alcohols under acidic conditions at ambient temperature. The macromolecular

  2. Synthesis and characterization of well-defined hydrogel matrices and their application to intestinal stem cell and organoid culture. (United States)

    Gjorevski, Nikolce; Lutolf, Matthias P


    Growing cells within an extracellular matrix-like 3D gel is required for, or can improve, the growth of many cell types ex vivo. Here, we describe a protocol for the generation of well-defined matrices for the culture of intestinal stem cells (ISCs) and intestinal organoids. These matrices comprise a poly(ethylene glycol) (PEG) hydrogel backbone functionalized with minimal adhesion cues including RGD (Arg-Gly-Asp), which is sufficient for ISC expansion, and laminin-111, which is required for organoid formation. As such, the hydrogels present a defined and reproducible, but also tunable, environment, allowing researches to manipulate physical and chemical parameters, and examine their influence on ISC and organoid growth. Hydrogels are formed by an enzymatic cross-linking reaction of multiarm PEG precursors bearing glutamine- and lysine-containing peptides. PEG precursors containing either stable or hydrolytically degradable moieties are used to produce mechanically softening hydrogels, which are used for the expansion of ISCs or the formation of organoids, respectively. We also provide protocols for immunofluorescence analysis of cellular structures grown within these matrices, as well as for their dissociation and retrieval of cells for downstream use. Hydrogel precursors can be produced and their mechanical properties characterized to ascertain stiffness within 5-7 d. Hydrogel formation for ISC expansion or organoid formation takes 1-2 h. The materials described here can be readily adapted for the culture of other types of normal or transformed organoid structures.

  3. A well-defined mesoporous amine silica surface via a selective treatment of SBA-15 with ammonia

    KAUST Repository

    Bendjeriou-Sedjerari, Anissa


    2D double-quantum 1H- 1H NMR unambiguously shows that the "isolated" Si-OH surface silanols of dehydroxylated SBA-15 are converted upon treatment with ammonia into single silylamine surface site Si-NH 2. The "gem" di-silanols (Si(OH) 2) remain intact. Treatment using HMDS produces (Si(OSiMe 3) 2) but leaves Si-NH 2 untouched. The resulting surface is hydrophobic and stable. © The Royal Society of Chemistry 2012.

  4. Well-Defined Bilayered Molecular Cobrushes with Internal Polyethylene Blocks and ω-Hydroxyl-Functionalized Polyethylene Homobrushes

    KAUST Repository

    Zhang, Hefeng


    Novel well-defined bilayered molecular cobrushes with internal polyethylene blocks, P(PEcore-b-PScorona) (PE: polyethylene; PS: polystyrene), and ω-hydroxyl-functionalized polyethylene homobrushes, P(PE-OH), were synthesized through the macromonomer strategy. Two main steps were involved in the synthesis of the P(PEcore-b-PScorona) bilayered cobrushes: (i) formation of norbornyl-terminated macromonomer (Nor-PE-b-PS) by esterification of PS-b-PE-OH (combination of anionic polymerization, hydroboration, and polyhomologation) with 5-norbornene-2-carboxylic acid and (ii) ring-opening metathesis polymerization (ROMP) of Nor-PE-b-PS. The synthesis of P(PE-OH) was achieved by (i) hydroboration of tert-butyldimethylsilyl-protected allyl alcohol, followed by polyhomologation of dimethylsulfoxoniun methylide with the formed tri[3-(tert-butyldimethylsilyloxyl)propyl]borane initiator, oxidation/hydrolysis, and esterification of the TBDMS-O-PE-OH with 5-norbornene-2-carboxylic acid to afford the macromonomer TBDMS-O-PE-Nor, and (ii) ROMP of TBDMS-O-PE-Nor, followed by deprotection. Nuclear magnetic resonance spectroscopy (1H and 13C NMR) and high temperature gel permeation chromatography (HT-GPC) were used to characterize all macromonomers/molecular brushes and differential scanning calorimetry (DSC) to study the thermal properties. The molecular brush P(PE-b-PS) showed lower melting point (Tm) and better solubility in toluene than the corresponding macromonomer PS-b-PE-Nor. In the case of homobrushes, the thermal properties were strongly affected by the presence of the PE end-groups. © 2016 American Chemical Society.

  5. Optimization of the alpha image reconstruction - an iterative CT-image reconstruction with well-defined image quality metrics. (United States)

    Lebedev, Sergej; Sawall, Stefan; Knaup, Michael; Kachelrieß, Marc


    Optimization of the AIR-algorithm for improved convergence and performance. The AIR method is an iterative algorithm for CT image reconstruction. As a result of its linearity with respect to the basis images, the AIR algorithm possesses well defined, regular image quality metrics, e.g. point spread function (PSF) or modulation transfer function (MTF), unlike other iterative reconstruction algorithms. The AIR algorithm computes weighting images α to blend between a set of basis images that preferably have mutually exclusive properties, e.g. high spatial resolution or low noise. The optimized algorithm uses an approach that alternates between the optimization of rawdata fidelity using an OSSART like update and regularization using gradient descent, as opposed to the initially proposed AIR using a straightforward gradient descent implementation. A regularization strength for a given task is chosen by formulating a requirement for the noise reduction and checking whether it is fulfilled for different regularization strengths, while monitoring the spatial resolution using the voxel-wise defined modulation transfer function for the AIR image. The optimized algorithm computes similar images in a shorter time compared to the initial gradient descent implementation of AIR. The result can be influenced by multiple parameters that can be narrowed down to a relatively simple framework to compute high quality images. The AIR images, for instance, can have at least a 50% lower noise level compared to the sharpest basis image, while the spatial resolution is mostly maintained. The optimization improves performance by a factor of 6, while maintaining image quality. Furthermore, it was demonstrated that the spatial resolution for AIR can be determined using regular image quality metrics, given smooth weighting images. This is not possible for other iterative reconstructions as a result of their non linearity. A simple set of parameters for the algorithm is discussed that provides

  6. Optimization of the alpha image reconstruction. An iterative CT-image reconstruction with well-defined image quality metrics

    Energy Technology Data Exchange (ETDEWEB)

    Lebedev, Sergej; Sawall, Stefan; Knaup, Michael; Kachelriess, Marc [German Cancer Research Center, Heidelberg (Germany).


    Optimization of the AIR-algorithm for improved convergence and performance. TThe AIR method is an iterative algorithm for CT image reconstruction. As a result of its linearity with respect to the basis images, the AIR algorithm possesses well defined, regular image quality metrics, e.g. point spread function (PSF) or modulation transfer function (MTF), unlike other iterative reconstruction algorithms. The AIR algorithm computes weighting images α to blend between a set of basis images that preferably have mutually exclusive properties, e.g. high spatial resolution or low noise. The optimized algorithm uses an approach that alternates between the optimization of rawdata fidelity using an OSSART like update and regularization using gradient descent, as opposed to the initially proposed AIR using a straightforward gradient descent implementation. A regularization strength for a given task is chosen by formulating a requirement for the noise reduction and checking whether it is fulfilled for different regularization strengths, while monitoring the spatial resolution using the voxel-wise defined modulation transfer function for the AIR image. The optimized algorithm computes similar images in a shorter time compared to the initial gradient descent implementation of AIR. The result can be influenced by multiple parameters that can be narrowed down to a relatively simple framework to compute high quality images. The AIR images, for instance, can have at least a 50% lower noise level compared to the sharpest basis image, while the spatial resolution is mostly maintained. The optimization improves performance by a factor of 6, while maintaining image quality. Furthermore, it was demonstrated that the spatial resolution for AIR can be determined using regular image quality metrics, given smooth weighting images. This is not possible for other iterative reconstructions as a result of their non linearity. A simple set of parameters for the algorithm is discussed that provides

  7. Surface modification with well-defined biocompatible triblock copolymers Improvement of biointerfacial phenomena on a poly(dimethylsiloxane) surface. (United States)

    Iwasaki, Yasuhiko; Takamiya, Mika; Iwata, Ryoko; Yusa, Shin-Ichi; Akiyoshi, Kazunari


    To improve interfacial phenomena of poly(dimethylsiloxane) (PDMS) as biomaterials, well-defined triblock copolymers were prepared as coating materials by reversible addition-fragmentation chain transfer (RAFT) controlled polymerization. Hydroxy-terminated poly(vinylmethylsiloxane-co-dimethylsiloxane) (HO-PV(l)D(m)MS-OH) was synthesized by ring-opening polymerization. The copolymerization ratio of vinylmethylsiloxane to dimethylsiloxane was 1/9. The molecular weight of HO-PV(l)D(m)MS-OH ranged from (1.43 to 4.44)x10(4), and their molecular weight distribution (M(w)/M(n)) as determined by size-exclusion chromatography equipped with multiangle laser light scattering (SEC-MALS) was 1.16. 4-Cyanopentanoic acid dithiobenzoate was reacted with HO-PV(l)D(m)MS-OH to obtain macromolecular chain transfer agents (macro-CTA). 2-Methacryloyloxyethyl phosphorylcholine (MPC) was polymerized with macro-CTAs. The gel-permeation chromatography (GPC) chart of synthesized polymers was a single peak and M(w)/M(n) was relatively narrow (1.3-1.6). Then the poly(MPC) (PMPC)-PV(l)D(m)MS-PMPC triblock copolymers were synthesized. The molecular weight of PMPC in a triblock copolymer was easily controllable by changing the polymerization time or the composition of the macro-CTA to a monomer in the feed. The synthesized block copolymers were slightly soluble in water and extremely soluble in ethanol and 2-propanol. Surface modification was performed via hydrosilylation. The block copolymer was coated on the PDMS film whose surface was pretreated with poly(hydromethylsiloxane). The surface wettability and lubrication of the PDMS film were effectively improved by immobilization with the block copolymers. In addition, the number of adherent platelets from human platelet-rich plasma (PRP) was dramatically reduced by surface modification. Particularly, the triblock copolymer having a high composition ratio of MPC units to silicone units was effective in improving the surface properties of PDMS. By

  8. Phosphoniums as catalysts for metal-free polymerization: Synthesis of well-defined poly(propylene oxide) (United States)

    Zhang, Jie; Liu, Quan; Ren, Haojun; Zhang, Nanjie; Li, Pengfei; Yang, Kang


    The anionic ring-opening polymerization of propylene oxide (PO) was initiated with glycerol and catalyzed by three new synthetic phosphonium salts, tetrakis (pyrrolidino) phosphonium (Py4P1+), tetrakis (piperidino) phosphonium (Pi4P1+), tetrakis (morpholino) phosphonium (Mo4P1+), and the known tetrakis [cyclohexyl (methyl) amino] phosphonium (Cy4P1+) and tetrakis [tris (dimethylamino) phosphonoamino] phosphazene (P5+). The effects of substituents on the polymerization behavior, especially the molecular weight and its distribution, degree of unsaturation, and the sequential structures of poly (propylene oxide) (PPO) were investigated. The structures of these catalysts and PPOs were characterized by FT-IR, 1H and 13C NMR, and GPC. The results indicate that Cy4P1+, Py4P1+, and Pi4P1+ have lower optimum reaction temperatures at 90, 70, and 70 °C, respectively, and are better than traditional catalysts KOH and double metal cyanide. PPO samples with high molecular weight, narrow polydispersity, and high functionality were accessible when catalyzed with Cy4P1+, Pi4P1+, and P5+ at the optimum temperature. Notably, Pi4P1+ formed unimodal distribution PPO with 9000 g/mol, 2.93 of functionality, and 0.008 mmol/g degree of unsaturation. Majority segments of PPO from five catalysts adopted the stereoregular head-to-tail structure, exhibiting excellent regularity.

  9. Macromolecular Engineering: New Routes Towards the Synthesis of Well-??Defined Polyethers/Polyesters Co/Terpolymers with Different Architectures

    KAUST Repository

    Alamri, Haleema


    The primary objective of this research was to develop a new and efficient pathway for well-defined multicomponent homo/co/terpolymers of cyclic esters/ethers using an organocatalytic approach with an emphasis on the macromolecular engineering aspects of the overall synthesis. Macromolecular engineering (as discussed in the first chapter) of homo/copolymers refers to the specific tailoring of these materials for achieving an easy and reproducible synthesis that results in precise molecular characteristics, i.e. molecular weight and polydispersity, as well as specific structure and end?group choices. Precise control of these molecular characteristics will provide access to new materials that can be used for pre-targeted purposes such as biomedical applications. Among the most commonly used engineering materials are polyesters (biocompatible and biodegradable) and polyethers (biocompatible), either as homopolymers or when or copolymers with linear structures. The ability to create non-linear structures, for example stars, will open new horizons in the applications of these important polymeric materials. The second part of this thesis describes the synthesis of aliphatic polyesters, particularly polycaprolactone and polylactide, using a metal-free initiator/catalyst system. A phosphazene base (t?BuP2) was used as the catalyst for the ring-opening copolymerization of ?-aprolactone (??CL) and L,Lactide (LLA) at room temperature with a variety of protic initiators in different solvents. These studies provided important information for the design of a metal-free route toward the synthesis of polyester?based (bio) materials. The third part of the thesis describes a novel route for the one?pot synthesis of polyether-b polyester block copolymers with either a linear or a specific macromolecular architecture. Poly (styrene oxide)?b?poly(caprolactone)?b?poly(L,lactide) was prepared using this method with the goal of synthesizing poly(styrene oxide)-based materials since this

  10. A well-defined silica-supported aluminium alkyl through an unprecedented, consecutive two-step protonolysis–alkyl transfer mechanism

    KAUST Repository

    Pelletier, Jérémie


    Impregnation of [(AliBu3)(Et2O)] on partially dehydroxylated SBA-15 affords a mesoporous material bearing the well-defined single site surface aluminium species [(≡SiO)2Al(iBu)(Et 2O)]. © The Royal Society of Chemistry.

  11. A Simple and Universal Gel Permeation Chromatography Technique for Precise Molecular Weight Characterization of Well-Defined Poly(ionic liquid)s

    Energy Technology Data Exchange (ETDEWEB)

    He, Hongkun; Zhong, Mingjiang; Adzima, Brian; Luebke, David; Nulwala, Hunaid; Matyjaszewski, Krzysztof


    Poly(ionic liquid)s (PILs) are an important class of technologically relevant materials. However, characterization of well-defined polyionic materials remains a challenge. Herein, we have developed a simple and versatile gel permeation chromatography (GPC) methodology for molecular weight (MW) characterization of PILs with a variety of anions. PILs with narrow MW distributions were synthesized via atom transfer radical polymerization, and the MWs obtained from GPC were further confirmed via nuclear magnetic resonance end group analysis.

  12. PHEA-g-PMMA Well-Defined Graft Copolymer: ATRP Synthesis, Self-Assembly, and Synchronous Encapsulation of Both Hydrophobic and Hydrophilic Guest Molecules. (United States)

    Ding, Aishun; Xu, Jie; Gu, Guangxin; Lu, Guolin; Huang, Xiaoyu


    A series of well-defined amphiphilic graft copolymer bearing a hydrophilic poly(2-hydroxyethyl acrylate) (PHEA) backbone and hydrophobic poly(methyl methacrylate) (PMMA) side chains was synthesized by successive reversible addition-fragmentation chain transfer (RAFT) polymerization and atom transfer radical polymerization (ATRP) through the grafting-from strategy. A well-defined PHEA-based backbone with Cl-containing ATRP initiating group in every repeated unit (M w /M n  = 1.08), poly(2-hydroxyethyl 2-((2-chloropropanoyloxy)methyl)acrylate) (PHECPMA), was first prepared by RAFT homopolymerization of 2-hydroxyethyl 2-((2-chloropropanoyloxy)methyl)acrylate (HECPMA), a Cl-containing trifunctional acrylate. ATRP of methyl methacrylate was subsequently initiated by PHECPMA homopolymer to afford the target well-defined poly(2-hydroxyethyl acrylate)-graft-poly(methyl methacrylate) (PHEA-g-PMMA) graft copolymers (M w /M n  ≤ 1.36) with 34 PMMA side chains and 34 pendant hydroxyls in PHEA backbone using CuCl/dHbpy as catalytic system. The critical micelle concentration (cmc) of the obtained graft copolymer was determined by fluorescence spectroscopy using N-phenyl-1-naphthylamine as probe while micellar morphologies in aqueous media were visualized by transmission electron microscopy. Interestingly, PHEA-g-PMMA graft copolymer could self-assemble into large compound micelles rather than common spherical micelles, which can encapsulate hydrophilic rhodamine 6 G and hydrophobic pyrene separately or simultaneously.

  13. A well-defined Pd hybrid material for the Z-selective semihydrogenation of alkynes characterized at the molecular level by DNP SENS. (United States)

    Conley, Matthew P; Drost, Ruben M; Baffert, Mathieu; Gajan, David; Elsevier, Cornelis; Franks, W Trent; Oschkinat, Hartmut; Veyre, Laurent; Zagdoun, Alexandre; Rossini, Aaron; Lelli, Moreno; Lesage, Anne; Casano, Gilles; Ouari, Olivier; Tordo, Paul; Emsley, Lyndon; Copéret, Christophe; Thieuleux, Chloé


    Direct evidence of the conformation of a Pd-N heterocyclic carbene (NHC) moiety imbedded in a hybrid material and of the Pd-NHC bond were obtained by dynamic nuclear polarization surface-enhanced NMR spectroscopy (DNP SENS) at natural abundance in short experimental times (hours). Overall, this silica-based hybrid material containing well-defined Pd-NHC sites in a uniform environment displays high activity and selectivity in the semihydrogenation of alkynes into Z-alkenes (see figure). Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. A combined UHV-STM-flow cell set-up for electrochemical/electrocatalytic studies of structurally well-defined UHV prepared model electrodes

    DEFF Research Database (Denmark)

    Schnaidt, J.; Beckord, S.; Engstfeld, Albert Kilian


    We describe the construction and discuss the performance of a novel combined ultrahigh vacuum (UHV)-electrochemistry set-up, allowing the controlled preparation and structural characterization of complex nanostructured electrode surfaces by high resolution scanning tunnelling microscopy (STM) under...... collector electrode or by differential electrochemical mass spectrometry (DEMS). The potential of the set-up will be illustrated in two electrocatalytic reactions on complex, but structurally well-defined bimetallic electrode surfaces, O-2 reduction on PtxAg1-x/Pt(111) monolayer surface alloys and bulk CO...

  15. Unearthing a Well-Defined Highly Active Bimetallic W/Ti Precatalyst Anchored on a Single Silica Surface for Metathesis of Propane

    KAUST Repository

    Samantaray, Manoja


    Two compatible organometallic complexes, W(Me)(6) (1) and TiNp4 (2), were successively anchored on a highly dehydroxylated single silica support (SiO2-700) to synthesize the well-defined bimetallic precatalyst [(equivalent to Si-O-)W(Me)(5)(equivalent to Si-O-)Ti(Np)(3)] (4). Precatalyst 4 was characterized at the molecular level using advanced surface organometallic chemistry (SOMC) characterization techniques. The strong autocorrelation observed between methyl of W and Ti in H-1-H-1 multiple-quantum NMR spectra demonstrates that W and Ti species are in close proximity to each other. The bimetallic precatalyst 4, with a turnover number (TON) of 9784, proved to be significantly more efficient than the silica-supported monometallic catalyst [(equivalent to Si-O-)W(Me)(5)] (3), with a TON of 98, for propane metathesis at 150 degrees C in a flow reactor. The dramatic improvement in the activity signifies the cooperativity between Ti and W and indicates that the key step of alkane metathesis (C-H bond activation followed by beta-H elimination) occurs on Ti, followed by olefin metathesis, which occurs on W. We have demonstrated the influence and importance of proximity of Ti to W for achieving such a significantly high activity. This is the first report demonstrating the considerably high activity (TON = 9784) in propane metathesis at moderate temperature (150 degrees C) using a well-defined bimetallic system prepared via the SOMC approach.

  16. Unearthing a Well-Defined Highly Active Bimetallic W/Ti Precatalyst Anchored on a Single Silica Surface for Metathesis of Propane. (United States)

    Samantaray, Manoja K; Kavitake, Santosh; Morlanés, Natalia; Abou-Hamad, Edy; Hamieh, Ali; Dey, Raju; Basset, Jean-Marie


    Two compatible organometallic complexes, W(Me)6 (1) and TiNp4 (2), were successively anchored on a highly dehydroxylated single silica support (SiO2-700) to synthesize the well-defined bimetallic precatalyst [(≡Si-O-)W(Me)5(≡Si-O-)Ti(Np)3] (4). Precatalyst 4 was characterized at the molecular level using advanced surface organometallic chemistry (SOMC) characterization techniques. The strong autocorrelation observed between methyl of W and Ti in (1)H-(1)H multiple-quantum NMR spectra demonstrates that W and Ti species are in close proximity to each other. The bimetallic precatalyst 4, with a turnover number (TON) of 9784, proved to be significantly more efficient than the silica-supported monometallic catalyst [(≡Si-O-)W(Me)5] (3), with a TON of 98, for propane metathesis at 150 °C in a flow reactor. The dramatic improvement in the activity signifies the cooperativity between Ti and W and indicates that the key step of alkane metathesis (C-H bond activation followed by β-H elimination) occurs on Ti, followed by olefin metathesis, which occurs on W. We have demonstrated the influence and importance of proximity of Ti to W for achieving such a significantly high activity. This is the first report demonstrating the considerably high activity (TON = 9784) in propane metathesis at moderate temperature (150 °C) using a well-defined bimetallic system prepared via the SOMC approach.

  17. Tailor-made starch-based conjugates containing well-defined poly(vinyl acetate and its derivative poly(vinyl alcohol

    Directory of Open Access Journals (Sweden)


    Full Text Available Reversible addition-fragmentation chain transfer (RAFT polymerization was adopted to synthesize starch-based conjugates that possessed controllable architecture and properties. Starch-based xanthate agent was prepared and applied as chain transfer agent to conduct the living/controlled polymerization (LCP of vinyl acetate, which generated tailor-made conjugates of starch and well-defined poly(vinyl acetate (SVAc. The relevant derivatives, conjugates of starch and chain length-controlled poly(vinyl alcohol (SVA, were obtained subsequently. Various characterizations such as Fourier transform infrared spectra (FTIR, ultraviolet-visible spectroscopy (UV, proton nuclear magnetic resonance (1H NMR, gel permeation chromatography (GPC, X-ray diffraction (XRD, Thermogravimetric analysis (TGA, and dynamic mechanical thermal analysis (DMTA were performed to examine the structure of intermediates and the starch-based conjugates. Static contact angle measurements revealed that the hydrophilic character of starch-based conjugates was tunable. Well-defined SVAc was amphiphilic and it was able to self-assemble into size controllable micelles, which was verified by contact angles, transmission electron microscopy (TEM and dynamic light scattering (DLS tests. SVA exhibited much higher capability to form physically cross-linked hydrogel than starch did. Both the characteristic of SVAc and SVA were chain length-dependent.

  18. Solid-State NMR and DFT Studies on the Formation of Well-Defined Silica-Supported Tantallaaziridines: From Synthesis to Catalytic Application

    KAUST Repository

    Hamzaoui, Bilel


    Single-site, well-defined, silica-supported tantallaaziridine intermediates [≡Si-O-Ta(η2-NRCH2)(NMe2)2] [R=Me (2), Ph (3)] were prepared from silica-supported tetrakis(dimethylamido)tantalum [≡Si-O-Ta(NMe2)4] (1) and fully characterized by FTIR spectroscopy, elemental analysis, and 1H,13C HETCOR and DQ TQ solid-state (SS) NMR spectroscopy. The formation mechanism, by β-H abstraction, was investigated by SS NMR spectroscopy and supported by DFT calculations. The C-H activation of the dimethylamide ligand is favored for R=Ph. The results from catalytic testing in the hydroaminoalkylation of alkenes were consistent with the N-alkyl aryl amine substrates being more efficient than N-dialkyl amines. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. A Rare Case of Primary Intrapulmonary Neurilemmoma Diagnosed in a 43-Year-Old Asymptomatic Man with a Well-defined Intrapulmonary Mass. (United States)

    Chrysikos, Serafeim; Kaponi, Maria; Triantafillidou, Christina; Karampitsakos, Theodoros; Tzouvelekis, Argyrios; Anyfanti, Maria; Marossis, Konstantinos; Konstantinou, Marios; Tringidou, Rodoula; Bouros, Demosthenes; Dimakou, Katerina


    Neurilemmoma (NL), also termed schwannoma, presents as a well-circumscribed and encapsulated mass in the human body and is almost always solitary. CT scan of a patient with NL shows a round, ovoid, or lobulated well-demarcated solid mass of soft tissue density. Primary intrathoracic neurogenic tumors location varies. However, the development of such tumors is by far more common in the costovertebral angle of the posterior mediastinum. Here, we report a rare case of a 43-year-old patient, never smoker and previously healthy, who presented with a mass adjacent to the right pulmonary hilum. This was an incidental finding on a chest X-ray after annual checkup at his workplace. The diagnosis was primary intrapulmonary NL. Primary intrapulmonary NL is an extremely rare tumor. However, based on the above, chest CT findings of a well-defined solid mass in an asymptomatic patient should raise the suspicion of NL, irrespective of the tumor localization.

  20. Controllable assembly of well-defined monodisperse Au nanoparticles on hierarchical ZnO microspheres for enhanced visible-light-driven photocatalytic and antibacterial activity. (United States)

    Wang, Yuan; Fang, Hua-Bin; Zheng, Yan-Zhen; Ye, Rongqin; Tao, Xia; Chen, Jian-Feng


    A high-efficiency visible-light-driven photocatalyst composed of homogeneously distributed Au nanoparticles (AuNPs) well-defined on hierarchical ZnO microspheres (ZMS) via a controllable layer-by-layer self-assembly technique is demonstrated. The gradual growth of the characteristic absorption bands of Au loaded on ZnO in the visible light region with an increasing number of assemblies indicates the enhancement of the light harvesting ability of the ZMS/Au composites as well as the reproducibility and controllability of the entire assembly process. Results on the photoelectrochemical performance characterized by EIS and transient photocurrent response spectra indicate that the ZMS/Au composites possess increased photoinduced charge separation and transfer efficiency compared to the pure ZMS film. As a result, the hybrid composites exhibited enhanced decomposition activity for methylene blue and salicylic acid as well as antibacterial activity in killing S. aureus and E. coli under visible light irradiation. It can be noted that well-distributed Au components even at a rather low Au/ZnO weight ratio of ∼1.2% also exhibited extraordinary photocatalysis. Such a facile and controllable self-assembly approach may be viable for preparing high-performance visible-light-driven ZMS/Au photocatalysts in a simple and controllable way, and consequently, the technology may extend to other plasmon-enhanced heterostructures made of nanostructured semiconductors and noble metals for great potential application in environmental protection.

  1. A cuboctahedral platinum (Pt79) nanocluster enclosed by well defined facets favours di-sigma adsorption and improves the reaction kinetics for methanol fuel cells. (United States)

    Mahata, Arup; Choudhuri, Indrani; Pathak, Biswarup


    The methanol dehydrogenation steps are studied very systematically on the (111) facet of a cuboctahedral platinum (Pt79) nanocluster enclosed by well-defined facets. The various intermediates formed during the methanol decompositions are adsorbed at the edge and bridge site of the facet either vertically (through C- and O-centres) or in parallel. The di-sigma adsorption (in parallel) on the (111) facet of the nanocluster is the most stable structure for most of the intermediates and such binding improves the interaction between the substrate and the nanocluster and thus the catalytic activity. The reaction thermodynamics, activation barrier, and temperature dependent reaction rates are calculated for all the successive methanol dehydrogenation steps to understand the methanol decomposition mechanism, and these values are compared with previous studies to understand the catalytic activity of the nanocluster. We find the catalytic activity of the nanocluster is excellent while comparing with any previous reports and the methanol dehydrogenation thermodynamics and kinetics are best when the intermediates are adsorbed in a di-sigma manner.

  2. Rational and practical exfoliation of graphite using well-defined poly(3-hexylthiophene) for the preparation of conductive polymer/graphene composite. (United States)

    Iguchi, Hiroki; Higashi, Chisato; Funasaki, Yuichi; Fujita, Keisuke; Mori, Atsunori; Nakasuga, Akira; Maruyama, Tatsuo


    Processing and manipulation of highly conductive pristine graphene in large quantities are still major challenges in the practical application of graphene for electric device. In the present study, we report the liquid-phase exfoliation of graphite in toluene using well-defined poly(3-hexylthiophene) (P3HT) to produce a P3HT/graphene composite. We synthesize and use regioregular P3HT with controlled molecular weights as conductive dispersants for graphene. Simple ultrasonication of graphite flakes with the P3HT successfully produces single-layer and few-layer graphene sheets dispersed in toluene. The produced P3HT/graphene composite can be used as conductive graphene ink, indicating that the P3HT/graphene composite has high electrical conductivity owing to the high conductivity of P3HT and graphene. The P3HT/graphene composite also works as an oxidation-resistant and conductive film for a copper substrate, which is due to the high gas-barrier property of graphene.

  3. A Well-Defined Silicon Nanocone-Carbon Structure for Demonstrating Exclusive Influences of Carbon Coating on Silicon Anode of Lithium-Ion Batteries. (United States)

    Wang, Chao; Luo, Fei; Lu, Hao; Rong, Xiaohui; Liu, Bonan; Chu, Geng; Sun, Yu; Quan, Baogang; Zheng, Jieyun; Li, Junjie; Gu, Changzhi; Qiu, Xinping; Li, Hong; Chen, Liquan


    Nanotechnology and carbon coating have been applied to silicon anodes to achieve excellent lithium-ion batteries, but the exclusive influence of carbon coating on solid-electrolyte interphase (SEI) formation is difficult to exhibit distinctly because of the impurity and morphological irregularity of most nanostructured anodes. Here, we design a silicon nanocone-carbon (SNC-C) composite structure as a model anode to demonstrate the significant influences of carbon coating on SEI formation and electrochemical performance, unaffectedly as a result of pure electrode component and distinctly due to regular nanocone morphology. As demonstrated by morphological and elemental analysis, compared to the SNC electrode, the SNC-C electrode maintains a thinner SEI layer (∼10 nm) and more stable structure during cycling as well as longer cycle life (>725 cycles), higher Coulombic efficiency (>99%), and lower electrode polarization. This well-defined structure clearly shows the interface stability attributed to carbon coating and is promising in fundamental research of the silicon anode.

  4. Magnetic fluid control for viscous loss reduction of high-speed MRF brakes and clutches with well-defined fail-safe behavior (United States)

    Güth, Dirk; Schamoni, Markus; Maas, Jürgen


    No-load losses within brakes and clutches based on magnetorheological fluids are unavoidable and represent a major barrier towards their wide-spread commercial adoption. Completely torque free rotation is not yet possible due to persistent fluid contact within the shear gap. In this paper, a novel concept is presented that facilitates the controlled movement of the magnetorheological fluid from an active, torque-transmitting region into an inactive region of the shear gap. This concept enables complete decoupling of the fluid engaging surfaces such that viscous drag torque can be eliminated. In order to achieve the desired effect, motion in the magnetorheological fluid is induced by magnetic forces acting on the fluid, which requires an appropriate magnetic circuit design. In this investigation, we propose a methodology to determine suitable magnetic circuit designs with well-defined fail-safe behavior. The magnetically induced motion of magnetorheological fluids is modeled by the use of the Kelvin body force, and a multi-physics domain simulation is performed to elucidate various transitions between an engaged and disengaged operating mode. The modeling approach is validated by captured high-speed video frames which show the induced motion of the magnetorheological fluid due to the magnetic field. Finally, measurements performed with a prototype actuator prove that the induced viscous drag torque can be reduced significantly by the proposed magnetic fluid control methodology.

  5. Amphiphilic Fluorescent Well-Defined Living Polymer from Indole-3-Carboxaldehyde and 4-Bromo-1, 8-Naphthalic Anhydride: Synthesis and Characterization

    Directory of Open Access Journals (Sweden)

    Ambika Srivastava


    Full Text Available We reported a well-defined amphiphilic fluorescent polymer bearing indole repeating units with naphthalimide pendants obtained by ATRP followed by chemical modification. The obtained polymer poly (N-allyl indole-2-(4-hydroxybutyl-1, 8-naphthalimide (PAIHN was characterized by 1H NMR, FTIR, and GPC. The polymer showed a specific fluorescence emission maximum at 538 nm excited at 435 nm in aqueous solution. The amphiphilic nature of the polymer was investigated in aqueous solution using two spectroscopic methods, namely, absorption and emission spectroscopy. The Critical Miceller Concentration values obtained by UV-visible and fluorescence are in good agreement with each other. The micelles were characterized by TEM at concentration of 0.014 mg/mL. The polymer PAIHN prepared after tweaking exhibits green fluorescence at 538 nm due to the significant effect of naphthalimide moieties, whereas before tweaking the polymer poly (1-allyl indole-3-carbaldehyde (PAIC exhibits blue fluorescence at 425 nm due to indole repeating units of the polymer.

  6. Structural Analysis and Anticoagulant Activities of the Novel Sulfated Fucan Possessing a Regular Well-Defined Repeating Unit from Sea Cucumber

    Directory of Open Access Journals (Sweden)

    Mingyi Wu


    Full Text Available Sulfated fucans, the complex polysaccharides, exhibit various biological activities. Herein, we purified two fucans from the sea cucumbers Holothuria edulis and Ludwigothurea grisea. Their structures were verified by means of HPGPC, FT-IR, GC–MS and NMR. As a result, a novel structural motif for this type of polymers is reported. The fucans have a unique structure composed of a central core of regular (1→2 and (1→3-linked tetrasaccharide repeating units. Approximately 50% of the units from L. grisea (100% for H. edulis fucan contain sides of oligosaccharides formed by nonsulfated fucose units linked to the O-4 position of the central core. Anticoagulant activity assays indicate that the sea cucumber fucans strongly inhibit human blood clotting through the intrinsic pathways of the coagulation cascade. Moreover, the mechanism of anticoagulant action of the fucans is selective inhibition of thrombin activity by heparin cofactor II. The distinctive tetrasaccharide repeating units contribute to the anticoagulant action. Additionally, unlike the fucans from marine alga, although the sea cucumber fucans have great molecular weights and affluent sulfates, they do not induce platelet aggregation. Overall, our results may be helpful in understanding the structure-function relationships of the well-defined polysaccharides from invertebrate as new types of safer anticoagulants.

  7. Well-defined 4-arm stars with hydroxy-terminated polyethylene, polyethylene-b-polycaprolactone and polyethylene-b-(polymethyl methacrylate) 2 arms

    KAUST Repository

    Zhang, Zhen


    Bis-boron-thexyl-silaboracycle was prepared by hydroboration of 1,4-bis(methyldivinylsilyl)butane with thexylborane and used to initiate the polyhomologation of dimethylsulfoxonium methylide to afford well-defined hydroxy-terminated 4-arm polyethylene (PE) stars. The synthesized PE stars were transformed to (PE-b-PCL)4 starblock copolymers via the ring-opening polymerization of ϵ-caprolactone (CL) initiated by the hydroxyl end groups of (PE-OH)4 in the presence of P2-tBu phosphazene base. Esterification of the hydroxyl groups of the OH-terminated PE star with 2,2-dichloroacetyl chloride led to (PE-Cl2)4 which was used as initiator (eight initiating atom transfer radical polymerization, ATRP, sites) for the synthesis of (PE-b-PMMA2)4 dendrimer-like stars by the ATRP of methyl methacrylate (MMA). All intermediates and final products were characterized by high temperature gel permeation chromatography and proton nuclear magnetic resonance spectroscopy. © 2016 The Royal Society of Chemistry.

  8. Facile Synthesis of Multiblock Copolymers Containing Sequence-Controlled Peptides and Well-Defined Vinyl Polymers by Nitroxide-Mediated Polymerization. (United States)

    Nishimura, Shin-Nosuke; Higashi, Nobuyuki; Koga, Tomoyuki


    Precisely incorporating a wide range of structural and functional multiblocks along a polymer backbone is a significant challenge in polymer chemistry and offers promising opportunities to design highly ordered materials, including controlled polymer folding. Herein, a facile and versatile strategy for preparing functional multiblock copolymers composed of sequential peptides and well-defined vinyl polymers with a narrow polydispersity is reported. Cyclic oligopeptides have been developed that contain an alkoxyamine bond in the framework. By using this type of cyclic initiator, peptide-containing multiblock copolymers are successfully synthesized by nitroxide-mediated polymerization of styrene. To demonstrate the versatility of this method, radical (co)polymerizations were carried out for different monomers (p-chlorostyrene, 4-vinylpyridine, and styrene/acrylonitrile) and by three different cyclic peptide initiators with specific amino acid sequences. The resultant multiblock copolymer is foldable through intramolecular interactions between peptide blocks. It is believed that this approach will significantly advance the field of controlled polymer synthesis for complex structures and single-chain folding. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Amine-functionalized SBA-15 with uniform morphology and well-defined mesostructure for highly sensitive chemosensors to detect formaldehyde vapor. (United States)

    Zhu, Yongheng; Li, Hui; Zheng, Qi; Xu, Jiaqiang; Li, Xinxin


    Amine-functionalized SBA-15 with uniform morphology and well-defined mesostructure was prepared using a postgrafting route. The morphology, mesostructure, and functionality of the materials were characterized by scanning electron microscopy, transmission electron microscopy, small-angle X-ray scattering, nitrogen adsorption-desorption, Fourier transform infrared spectroscopy, and solid-state nuclear magnetic resonance spectroscopy techniques. The results show that hexagonal lamelliform SBA-15 with a uniform particle size and short vertical channels plays two significant roles in uniformly dispersing amine-functionalizing groups and effectively adjusting the loadings of the functional groups within the mesopore channels. To confirm the potential application of the hybrids in gas sensors, using amine-functionalized SBA-15 as a sensing material and a quartz crystal microbalance as a transducer, a parts per billion level formaldehyde sensor with high sensitivity (response time about 11 s, recovery time about 15 s) and good chemoselectivity was achieved. This material holds great potential in the area of rapid, sensitive, and highly convenient formaldehyde detection.

  10. Well-defined copolymers synthesized by RAFT polymerization as effective modifiers to enhance the photocatalytic performance of TiO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Vasilaki, E., E-mail: [Department of Chemistry, University of Crete, 710 03, Heraklion, Crete (Greece); Center of Materials Technology and Photonics, School of Applied Technology, Technological Educational Institute of Crete, 710 04 Heraklion, Crete (Greece); Kaliva, M. [Institute of Electronic Structure and Laser, Foundation for Research & Technology-Hellas, P.O. Box 1385, Vassilika Vouton, 711 10 Heraklion, Crete (Greece); Department of Materials Science and Technology, University of Crete, 710 03, Heraklion, Crete (Greece); Katsarakis, N. [Center of Materials Technology and Photonics, School of Applied Technology, Technological Educational Institute of Crete, 710 04 Heraklion, Crete (Greece); Institute of Electronic Structure and Laser, Foundation for Research & Technology-Hellas, P.O. Box 1385, Vassilika Vouton, 711 10 Heraklion, Crete (Greece); Vamvakaki, M. [Institute of Electronic Structure and Laser, Foundation for Research & Technology-Hellas, P.O. Box 1385, Vassilika Vouton, 711 10 Heraklion, Crete (Greece); Department of Materials Science and Technology, University of Crete, 710 03, Heraklion, Crete (Greece)


    Highlights: • Well-defined, random functional copolymers were synthesized by RAFT polymerization. • Novel TiO{sub 2} particles in-situ modified with copolymers were synthesized. • The hybrid catalysts exhibited reduced aggregation and particle size. • The photocatalytic removal of methylene blue was higher for the hybrid catalysts. - Αbstract: The enhancement of the photocatalytic performance of anatase TiO{sub 2} nanoparticles is demonstrated by a facile route, involving their in-situ surface modification with preformed polymer chains. Random copolymers of poly(ethylene glycol) methyl ether acrylate-co-methacrylic acid (PEGA-co-MAA) or poly(ethylene glycol) methyl ether acrylate-co-dopamine methacrylamide (PEGA-co-DMA) were synthesized by reversible addition−fragmentation chain-transfer (RAFT) polymerization and were bound onto the surface of anatase titania nanoparticles via the “grafting to” method. The hybrid nanocatalysts were characterized by fourier transform infrared spectroscopy, zeta-potential measurements, X-ray powder diffraction, thermogravimetric analysis and transmission electron microscopy. Their photocatalytic performance was evaluated by the decoloration of methylene blue (MB) dye in aqueous media under UV–vis light irradiation. The enhanced photoactivity and reusability of the polymer modified photocatalysts compared to that of bare TiO{sub 2} nanoparticles was attributed to their improved dispersability and colloidal stability, the smaller particle size that leads to a larger surface area and the increased adsorption capacity of the dye onto the polymer modified nanoparticles.

  11. Chitosan encapsulation of essential oil "cocktails" with well-defined binary Zn(II)-Schiff base species targeting antibacterial medicinal nanotechnology. (United States)

    Halevas, Eleftherios; Nday, Christiane M; Chatzigeorgiou, Evanthia; Varsamis, Vasileios; Eleftheriadou, Despoina; Jackson, Graham E; Litsardakis, Georgios; Lazari, Diamanto; Ypsilantis, Konstantinos; Salifoglou, Athanasios


    The advent of biodegradable nanomaterials with enhanced antibacterial activity stands as a challenge to the global research community. In an attempt to pursue the development of novel antibacterial medicinal nanotechnology, we herein a) synthesized ionic-gelated chitosan nanoparticles, b) compared and evaluated the antibacterial activity of essential oils extracted from nine different herbs (Greek origin) and their combinations with a well-defined antibacterial Zn(II)-Schiff base compound, and c) encapsulated the most effective hybrid combination of Zn(II)-essential oils inside the chitosan matrix, thereby targeting well-formulated nanoparticles of distinct biological impact. The empty and loaded chitosan nanoparticles were physicochemically characterized by FT-IR, Thermogravimetric Analysis (TGA), Scanning Electron Microscopy (SEM), with the entrapment and drug release studies being conducted through UV-Visible and atomic absorption techniques. The antimicrobial properties of the novel hybrid materials were demonstrated against Gram positive (S. aureus, B. subtilis, and B. cereus) and Gram negative (E. coli and X. campestris) bacteria using modified agar diffusion methods. The collective physicochemical profile of the hybrid Zn(II)-essential oil cocktails, formulated so as to achieve optimal activity when loaded to chitosan nanoparticles, signifies the importance of design in the development of efficient nanomedicinal pharmaceuticals a) based on both natural products and biogenic metal ionic cofactors, and b) targeting bacterial infections and drug resistance. Copyright © 2017 Elsevier Inc. All rights reserved.

  12. High-Hall-Mobility Al-Doped ZnO Films Having Textured Polycrystalline Structure with a Well-Defined (0001) Orientation. (United States)

    Nomoto, Junichi; Makino, Hisao; Yamamoto, Tetsuya


    Five hundred-nanometer-thick ZnO-based textured polycrystalline films consisting of 490-nm-thick Al-doped ZnO (AZO) films deposited on 10-nm-thick Ga-doped ZnO (GZO) films exhibited a high Hall mobility (μ H) of 50.1 cm(2)/Vs with a carrier concentration (N) of 2.55 × 10(20) cm(-3). Firstly, the GZO films were prepared on glass substrates by ion plating with dc arc discharge, and the AZO films were then deposited on the GZO films by direct current magnetron sputtering (DC-MS). The GZO interface layers with a preferential c-axis orientation play a critical role in producing AZO films with texture development of a well-defined (0001) orientation, whereas 500-nm-thick AZO films deposited by only DC-MS showed a mixture of the c-plane and the other plane orientation, to exhibit a μ H of 38.7 cm(2)/Vs with an N of 2.22 × 10(20) cm(-3).

  13. Bidimensional analysis of the phase behavior of a well-defined surfactant (C10E4)/oil (n-octane)/water-temperature system. (United States)

    Pizzino, Aldo; Molinier, Valérie; Catté, Marianne; Salager, Jean-Louis; Aubry, Jean-Marie


    The equilibrium phase behavior of the well-defined system tetraethyleneglycol decyl ether (C(10)E(4))/n-octane/water (SOW) at variable temperature (T) was revisited by careful analysis of the three bidimensional cuts, namely, the gamma (at constant water-oil ratio), chi (at constant surfactant concentration), and Delta (at constant temperature) plots. A straightforward methodology is reported to determine the frontiers of the triphasic (Winsor III) domain on any cut of the SOW-T phase prism. It comes from the systematic analysis of another cut, here gamma at different water-oil ratios and chi at different surfactant concentrations from the knowledge of Delta cuts at different temperatures. The method has been validated through comparison with experimental results. It enables one to show, for the first time, the evolution of a SOW system three-phase body contours with (i) water-oil ratio, (ii) surfactant concentration, and (iii) temperature. It exhibits a strong impact of the surfactant affinity for the pure oil and water phases on the shape of the phase diagrams. The systematic study of the effect of the surfactant concentration on the aspect of the chi plot sheds light on an unusual shape found at low surfactant concentration.

  14. Rational and practical exfoliation of graphite using well-defined poly(3-hexylthiophene) for the preparation of conductive polymer/graphene composite (United States)

    Iguchi, Hiroki; Higashi, Chisato; Funasaki, Yuichi; Fujita, Keisuke; Mori, Atsunori; Nakasuga, Akira; Maruyama, Tatsuo


    Processing and manipulation of highly conductive pristine graphene in large quantities are still major challenges in the practical application of graphene for electric device. In the present study, we report the liquid-phase exfoliation of graphite in toluene using well-defined poly(3-hexylthiophene) (P3HT) to produce a P3HT/graphene composite. We synthesize and use regioregular P3HT with controlled molecular weights as conductive dispersants for graphene. Simple ultrasonication of graphite flakes with the P3HT successfully produces single-layer and few-layer graphene sheets dispersed in toluene. The produced P3HT/graphene composite can be used as conductive graphene ink, indicating that the P3HT/graphene composite has high electrical conductivity owing to the high conductivity of P3HT and graphene. The P3HT/graphene composite also works as an oxidation-resistant and conductive film for a copper substrate, which is due to the high gas-barrier property of graphene.

  15. Facile preparation of well-defined hydrophilic core-shell upconversion nanoparticles for selective cell membrane glycan labeling and cancer cell imaging. (United States)

    Zhang, Wanjun; Peng, Bo; Tian, Fang; Qin, Weijie; Qian, Xiaohong


    Molecular imaging enables in situ visualization of biomolecules in living organisms and creates numerous opportunities for basic biological research and early disease diagnosis. As luminescent probes for molecular imaging, lanthanide-doped upconversion nanoparticles (UCNPs) exhibit superior performance compared to conventional fluorescent dyes in many ways, including high tissue penetration depth and minimized autofluorescence and photobleaching, making them particularly advantageous for imaging analysis. Although various synthesis methods have been reported, the preparation of high quality, water-soluble UCNPs remains challenging. For in situ imaging, glycans on the cell surface are particularly attractive due to their key roles in cellular activity and disease occurrence and development. However, glycan imaging is a challenging task due to their diverse structures and incompatibility with genetically encoded fluorescent tagging techniques. Herein, we report a new type of highly water-soluble, lectin-functionalized core-shell UCNP synthesized by surface-initiated atom transfer radical polymerization (SI-ATRP) for selective cell membrane glycan labeling and cancer cell imaging. SI-ATRP modification results in controlled growth of hydrophilic polymers on the UCNP surface and well-defined core-shell structure, producing UCNPs with improved biocompatibility and intact luminance property. Furthermore, the numerous functional groups on the polymer brush shell provide a large number of binding sites and 3D support for lectin immobilization. The increased loading density and diversified architecture of the immobilized lectins facilitates multivalent binding between the lectins and the glycans on the cell surface and leads to selective labeling of highly metastatic hepatocellular carcinoma cells (HCCHM3) in vitro and successful in vivo imaging of HCCHM3 inoculated mice.

  16. Surfactant-Free RAFT Emulsion Polymerization of Styrene Using Thermoresponsive macroRAFT Agents: Towards Smart Well-Defined Block Copolymers with High Molecular Weights

    Directory of Open Access Journals (Sweden)

    Steffen Eggers


    Full Text Available The combination of reversible addition–fragmentation chain transfer (RAFT and emulsion polymerization has recently attracted much attention as a synthetic tool for high-molecular-weight block copolymers and their micellar nano-objects. Up to recently, though, the use of thermoresponsive polymers as both macroRAFT agents and latex stabilizers was impossible in aqueous media due to their hydrophobicity at the usually high polymerization temperatures. In this work, we present a straightforward surfactant-free RAFT emulsion polymerization to obtain thermoresponsive styrenic block copolymers with molecular weights of around 100 kDa and their well-defined latexes. The stability of the aqueous latexes is achieved by adding 20 vol % of the cosolvent 1,4-dioxane (DOX, increasing the phase transition temperature (PTT of the used thermoresponsive poly(N-acryloylpyrrolidine (PAPy macroRAFT agents above the polymerization temperature. Furthermore, this cosolvent approach is combined with the use of poly(N,N-dimethylacrylamide-block-poly(N-acryloylpiperidine-co-N-acryloylpyrrolidine (PDMA-b-P(APi-co-APy as the macroRAFT agent owning a short stabilizing PDMA end block and a widely adjustable PTT of the P(APi-co-APy block in between 4 and 47 °C. The temperature-induced collapse of the latter under emulsion polymerization conditions leads to the formation of RAFT nanoreactors, which allows for a very fast chain growth of the polystyrene (PS block. In dynamic light scattering (DLS, as well as cryo-transmission electron microscopy (cryoTEM, moreover, all created latexes indeed reveal a high (temperature stability and a reversible collapse of the thermoresponsive coronal block upon heating. Hence, this paper pioneers a versatile way towards amphiphilic thermoresponsive high-molecular-weight block copolymers and their nano-objects with tailored corona switchability.

  17. Solvent-Controlled Branching of Localized versus Delocalized Singlet Exciton States and Equilibration with Charge Transfer in a Structurally Well-Defined Tetracene Dimer

    Energy Technology Data Exchange (ETDEWEB)

    Cook, Jasper D. [Department; Carey, Thomas J. [Department; Arias, Dylan H. [National Renewable Energy Laboratory, Golden, Colorado 80401, United States; Johnson, Justin C. [National Renewable Energy Laboratory, Golden, Colorado 80401, United States; Damrauer, Niels H. [Department


    A detailed photophysical picture is elaborated for a structurally well-defined and symmetrical bis-tetracene dimer in solution. The molecule was designed for interrogation of the initial photophysical steps (S1 - 1TT) in intramolecular singlet fission (SF). (Triisopropylsilyl)acetylene substituents on the dimer TIPS-BT1 as well as a monomer model TIPS-Tc enable a comparison of photophysical properties, including transient absorption dynamics, as solvent polarity is varied. In nonpolar toluene solutions, TIPS-BT1 decays via radiative and nonradiative pathways to the ground state with no evidence for dynamics related to the initial stages of SF. This contrasts with the behavior of the previously reported unsubstituted dimer BT1 and is likely a consequence of energetic perturbations to the singlet excited-state manifold of TIPS-BT1 by the (trialkylsilyl)acetylene substituents. In polar benzonitrile, two key findings emerge. First, photoexcited TIPS-BT1 shows a bifurcation into both arm-localized (S1-loc) and dimer-delocalized (S1-dim) singlet exciton states. The S1-loc decays to the ground state, and weak temperature dependence of its emissive signatures suggests that once it is formed, it is isolated from S1-dim. Emissive signatures of the S1-dim state, on the other hand, are strongly temperature-dependent, and transient absorption dynamics show that S1-dim equilibrates with an intramolecular charge-transfer state in 50 ps at room temperature. This equilibrium decays to the ground state with little evidence for formation of long-lived triplets nor 1TT. These detailed studies spectrally characterize many of the key states in intramolecular SF in this class of dimers but highlight the need to tune electronic coupling and energetics for the S1 - 1TT photoreaction.

  18. Gender-specific association between serotonin transporter polymorphisms (5-HTTLPR and rs25531) and neuroticism, anxiety and depression in well-defined healthy Han Chinese. (United States)

    Chang, Chuan-Chia; Chang, Hsin-An; Fang, Wen-Hui; Chang, Tieh-Ching; Huang, San-Yuan


    A tri-allelic serotonin transporter promoter polymorphism (5-HTTLPR/rs25531) more effectively determines the levels of transcriptional efficacy than that with the bi-allelic 5-HTTLPR polymorphism in vitro. Both are reportedly associated with personality traits of negative emotionality, but with conflicting findings. One explanation for this is that a gender difference may play a role in genetic contribution. Here, we hypothesized that the tri-allelic genotype of the serotonin transporter is more closely linked to neuroticism, an anxiety- and depression-related trait, than the bi-allelic variation, particularly in a gender-dependent way. The genotypes of the 5-HTTLPR and rs25531 loci were determined in 1139 well-defined physically and mentally healthy Han Chinese (550 men, 589 women; mean age 38.3±10.3 years). All participants completed the neuroticism measure of the short-form Maudsley Personality Inventory (MPI). The levels of anxiety and depression were assessed by the Beck Anxiety Inventory (BAI) and the Beck Depression Inventory (BDI), respectively. A significant tri-allelic genotype-by-gender interaction effect was found in the MPI-neuroticism measure. S'S' homozygotes were associated with higher neuroticism than L' allele carriers in men. Also, both the BAI and BDI scores were higher in the S'S' homozygotic men. In the bi-allelic analyses, however, there was only an association between SS genotype and MPI-neuroticism in men. Sub-analyses by gender-stratification may reduce the statistical power. Our findings confirm that gender differences exist in the genetic contributions of the serotonin transporter in human neuroticism, and anxiety/depression. Our data provide further support for rs25531, strengthening the effects of 5-HTTLPR. Copyright © 2016 Elsevier B.V. All rights reserved.

  19. A facile approach to TiO2 colloidal spheres decorated with Au nanoparticles displaying well-defined sizes and uniform dispersion. (United States)

    Damato, Tatiana C; de Oliveira, Caio C S; Ando, Rômulo A; Camargo, Pedro H C


    This paper describes a straightforward approach for the synthesis of hybrid materials composed of titanium dioxide (TiO(2)) colloidal spheres decorated with gold nanoparticles (Au NPs). In the reported method, monodisperse TiO(2) colloidal spheres (∼220 nm in diameter) could be directly employed as templates for the nucleation and growth of Au NPs over their surface using AuCl(4)(-)(aq) as the Au precursor, ascorbic acid as the reducing agent, PVP as the stabilizer, and water as the solvent. The Au NPs presented a uniform distribution over the TiO(2) surface. Interestingly, the size of the Au NPs could be controlled by performing sequential reduction steps with AuCl(4)(-)(aq). This method could also be adapted for the production of TiO(2) colloidal spheres decorated with other metal NPs including silver (Ag), palladium (Pd), and platinum (Pt). The catalytic activities of the TiO(2)-Au materials as a function of composition and NPs size were investigated toward the reduction of 4-nitrophenol to 4-aminophenol under ambient conditions. An increase of up to 10.3-fold was observed for TiO(2)-Au relative to TiO(2). A surface-enhanced Raman scattering application for TiO(2)-Au was also demonstrated employing 4-mercaptopyridine as the probe molecule. The results presented herein indicate that our approach may serve as a platform for the synthesis of hybrid materials containing TiO(2) and metal NPs displaying well-defined morphologies, compositions, and sizes. This can have important implications for the design of TiO(2)-based materials with improved performances for photocatalysis and photovoltaic applications.

  20. Hydro-Metathesis of Long-Chain Olefin (1-decene) using Well-Defined Silica-Supported Tungsten (VI), Molybdenum (VI) and Tantalum (V) Catalysts

    KAUST Repository

    Saidi, Aya


    Nowadays, catalysis lies at the heart of economy growth mainly in the petroleum industry. Catalysis can offer real and potential solutions to the current challenges for a long-term sustainable energy, green chemistry, and environmental protection. In this context, one of the most important and future prosperity promising catalytic applications in the petrochemical field is hydrocarbons metathesis; it consists on the conversion of both renewable and non-petroleum fossil carbon sources to transportation fuels. Olefin metathesis has become one of the standard methodologies for constructing C-C bonds in many organic transformation reactions. This owed to the numerous types of metathesis reactions that have been developed, for example, enyne, ring-opening and closing, self and cross metathesis, etc. But the one step conversion of olefin to alkanes has not been studied much. Recently, only one such a work has been published for the hydro-metathesis of propylene by tantalum hydride supported on KCC-1 in dynamic reactor. With this knowledge, we thought to study the hydro-metathesis using liquid olefin (1-decene). Another aspect of using 1-decene comes from our previous experience on metathesis of n-decane where the first step is the conversion of decane to 1-decene and subsequently to different chain length alkanes with W-alkyl/alkylidene catalyst. In this way, it would be easy for us to use different catalysts and compare them with parent catalyst concerning TON. We found 100% conversion with TON of 1010 using supported WMe6 onto SiO2-700 [(≡Si-O-)WMe5] against the previous results for n-decane showing 20% conversion and TON of 153. In this work, we disclose the hydro-metathesis reaction of 1-decene using well-defined silica supported W(VI), Mo(VI) and Ta(V) alkyl catalysts in batch reactor condition. This work is divided into three major sections; first chapter contains an introduction to the field of catalysis and surface organometallic chemistry. In second chapter

  1. High field electron paramagnetic resonance spectroscopy under ultrahigh vacuum conditions—A multipurpose machine to study paramagnetic species on well defined single crystal surfaces (United States)

    Rocker, J.; Cornu, D.; Kieseritzky, E.; Seiler, A.; Bondarchuk, O.; Hänsel-Ziegler, W.; Risse, T.; Freund, H.-J.


    A new ultrahigh vacuum (UHV) electron paramagnetic resonance (EPR) spectrometer operating at 94 GHz to investigate paramagnetic centers on single crystal surfaces is described. It is particularly designed to study paramagnetic centers on well-defined model catalysts using epitaxial thin oxide films grown on metal single crystals. The EPR setup is based on a commercial Bruker E600 spectrometer, which is adapted to ultrahigh vacuum conditions using a home made Fabry Perot resonator. The key idea of the resonator is to use the planar metal single crystal required to grow the single crystalline oxide films as one of the mirrors of the resonator. EPR spectroscopy is solely sensitive to paramagnetic species, which are typically minority species in such a system. Hence, additional experimental characterization tools are required to allow for a comprehensive investigation of the surface. The apparatus includes a preparation chamber hosting equipment, which is required to prepare supported model catalysts. In addition, surface characterization tools such as low energy electron diffraction (LEED)/Auger spectroscopy, temperature programmed desorption (TPD), and infrared reflection absorption spectroscopy (IRAS) are available to characterize the surfaces. A second chamber used to perform EPR spectroscopy at 94 GHz has a room temperature scanning tunneling microscope attached to it, which allows for real space structural characterization. The heart of the UHV adaptation of the EPR experiment is the sealing of the Fabry-Perot resonator against atmosphere. To this end it is possible to use a thin sapphire window glued to the backside of the coupling orifice of the Fabry Perot resonator. With the help of a variety of stabilization measures reducing vibrations as well as thermal drift it is possible to accumulate data for a time span, which is for low temperature measurements only limited by the amount of liquid helium. Test measurements show that the system can detect paramagnetic

  2. Synthesis and property investigations of well-defined polymer/inorganic core-shell nanomaterials with structural, optical, electronic and magnetic properties (United States)

    Gravano, Stefanie Marie

    (methyl methacrylate) (pMMA) which can function as strength enhancers in a material, (2) as wave-guides in electro-optical applications by grafting a non-linear optical (NLO) molecule to a nano-sized core, (3) as a conductive medium by developing a conductive poly(thiophene) (pT) polymerization method to functionalize an core structure, and (4) as a nano-sized magnetic core encased in a well-defined poly(styrene) (pS) matrix.

  3. High field electron paramagnetic resonance spectroscopy under ultrahigh vacuum conditions—A multipurpose machine to study paramagnetic species on well defined single crystal surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Rocker, J.; Cornu, D.; Kieseritzky, E.; Hänsel-Ziegler, W.; Freund, H.-J. [Fritz-Haber-Institut der MPG, Faradayweg 4-6, 14195 Berlin (Germany); Seiler, A. [Fritz-Haber-Institut der MPG, Faradayweg 4-6, 14195 Berlin (Germany); Laboratorium für Applikationen der Synchrotronstrahlung, KIT Campus Süd, Kaiserstr. 12, 76131 Karlsruhe (Germany); Bondarchuk, O. [Fritz-Haber-Institut der MPG, Faradayweg 4-6, 14195 Berlin (Germany); CIC energiGUNE, Parque Tecnologico, C/Albert Einstein 48, CP 01510 Minano (Alava) (Spain); Risse, T., E-mail: [Fritz-Haber-Institut der MPG, Faradayweg 4-6, 14195 Berlin (Germany); Institut für Chemie und Biochemie, Freie Universität Berlin, Takustr. 3, 14195 Berlin (Germany)


    A new ultrahigh vacuum (UHV) electron paramagnetic resonance (EPR) spectrometer operating at 94 GHz to investigate paramagnetic centers on single crystal surfaces is described. It is particularly designed to study paramagnetic centers on well-defined model catalysts using epitaxial thin oxide films grown on metal single crystals. The EPR setup is based on a commercial Bruker E600 spectrometer, which is adapted to ultrahigh vacuum conditions using a home made Fabry Perot resonator. The key idea of the resonator is to use the planar metal single crystal required to grow the single crystalline oxide films as one of the mirrors of the resonator. EPR spectroscopy is solely sensitive to paramagnetic species, which are typically minority species in such a system. Hence, additional experimental characterization tools are required to allow for a comprehensive investigation of the surface. The apparatus includes a preparation chamber hosting equipment, which is required to prepare supported model catalysts. In addition, surface characterization tools such as low energy electron diffraction (LEED)/Auger spectroscopy, temperature programmed desorption (TPD), and infrared reflection absorption spectroscopy (IRAS) are available to characterize the surfaces. A second chamber used to perform EPR spectroscopy at 94 GHz has a room temperature scanning tunneling microscope attached to it, which allows for real space structural characterization. The heart of the UHV adaptation of the EPR experiment is the sealing of the Fabry-Perot resonator against atmosphere. To this end it is possible to use a thin sapphire window glued to the backside of the coupling orifice of the Fabry Perot resonator. With the help of a variety of stabilization measures reducing vibrations as well as thermal drift it is possible to accumulate data for a time span, which is for low temperature measurements only limited by the amount of liquid helium. Test measurements show that the system can detect paramagnetic

  4. Terminal uranium(V/VI) nitride activation of carbon dioxide and carbon disulfide. Factors governing diverse and well-defined cleavage and redox reactions

    Energy Technology Data Exchange (ETDEWEB)

    Cleaves, Peter A.; Gardner, Benedict M.; Liddle, Stephen T. [School of Chemistry, The University of Manchester (United Kingdom); Kefalidis, Christos E.; Maron, Laurent [LPCNO, CNRS and INSA, Universite Paul Sabatier, Toulouse (France); Tuna, Floriana; McInnes, Eric J.L. [School of Chemistry and Photon Science Institute, The University of Manchester (United Kingdom); Lewis, William [School of Chemistry, The University of Nottingham (United Kingdom)


    The reactivity of terminal uranium(V/VI) nitrides with CE{sub 2} (E=O, S) is presented. Well-defined C=E cleavage followed by zero-, one-, and two-electron redox events is observed. The uranium(V) nitride [U(Tren{sup TIPS})(N)][K(B15C5){sub 2}] (1, Tren{sup TIPS}=N(CH{sub 2}CH{sub 2}NSiiPr{sub 3}){sub 3}; B15C5=benzo-15-crown-5) reacts with CO{sub 2} to give [U(Tren{sup TIPS})(O)(NCO)][K(B15C5){sub 2}] (3), whereas the uranium(VI) nitride [U(Tren{sup TIPS})(N)] (2) reacts with CO{sub 2} to give isolable [U(Tren{sup TIPS})(O)(NCO)] (4); complex 4 rapidly decomposes to known [U(Tren{sup TIPS})(O)] (5) with concomitant formation of N{sub 2} and CO proposed, with the latter trapped as a vanadocene adduct. In contrast, 1 reacts with CS{sub 2} to give [U(Tren{sup TIPS})(κ{sup 2}-CS{sub 3})][K(B15C5){sub 2}] (6), 2, and [K(B15C5){sub 2}][NCS] (7), whereas 2 reacts with CS{sub 2} to give [U(Tren{sup TIPS})(NCS)] (8) and ''S'', with the latter trapped as Ph{sub 3}PS. Calculated reaction profiles reveal outer-sphere reactivity for uranium(V) but inner-sphere mechanisms for uranium(VI); despite the wide divergence of products the initial activation of CE{sub 2} follows mechanistically related pathways, providing insight into the factors of uranium oxidation state, chalcogen, and NCE groups that govern the subsequent divergent redox reactions that include common one-electron reactions and a less-common two-electron redox event. Caution, we suggest, is warranted when utilising CS{sub 2} as a reactivity surrogate for CO{sub 2}. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

  5. Generation of Well-Defined Pairs of Silylamine on Highly Dehydroxylated SBA-15: Application to the Surface Organometallic Chemistry of Zirconium

    KAUST Repository

    Azzi, Joachim


    Design of a new well-defined surface organometallic species [O-(=Si–NH)2Zr(IV)Np2] has been obtained by reaction of tetraneopentyl zirconium (ZrNp4) on SBA-15 surface displaying mainly silylamine pairs [O-(=Si–NH2)2]. These surface species have been achieved by an ammonia treatment of a highly dehydroxylated SBA-15 at 1000°C (SBA-151000). This support is known to contain mainly strained reactive siloxane bridges (≡Si-O-Si≡)[1] along with a small amount of isolated plus germinal silanols =Si(OH)2. Chemisorption of ammonia occurs primarily by opening these siloxane bridges[2] to generate silanol/silylamine pairs [O-(=Si–NH2)(=SiOH)] followed by substitution of the remaining silanol. Further treatment using hexamethyldisilazane (HMDS) results in the protection of the isolated remaining silanol groups by formation of ≡Si-O-SiMe3 and =Si(OSiMe3)2 but leaves ≡SiNH2 untouched. After reaction of this functionalized surface with ZrNp4, this latter displays mainly a bi-podal zirconium neopentyl organometallic complex [O-(=Si–NH)2Zr(IV)Np2] which has been fully characterized by diverse methods such as infrared transmission spectroscopy, magic angle spinning solid state nuclear magnetic resonance, surface elemental analysis, small angle X-ray powder diffraction (XRD), nitrogen adsorption and energy filtered transmission electron microscopy (EFTEM). These different characterization tools unambiguously prove that the zirconium organometallic complex reacts mostly with silylamine pairs to give a bi-podal zirconium bis-neopentyl complex, uniformly distributed into the channels of SBA-151000. Therefore this new material opens a new promising research area in Surface Organometallic Chemistry which, so far, was dealing mainly with O containing surface. It is expected that vicinal amine functions may play a very different role as compared with classical inorganic supports. Given the importance in the last decades of N containing ligands in catalysis, one may expect

  6. Consistent Prebiotic Effect on Gut Microbiota With Altered FODMAP Intake in Patients with Crohn's Disease: A Randomised, Controlled Cross-Over Trial of Well-Defined Diets. (United States)

    Halmos, Emma P; Christophersen, Claus T; Bird, Anthony R; Shepherd, Susan J; Muir, Jane G; Gibson, Peter R


    Altering FODMAP (fermentable oligosaccharides, disaccharides, monosaccharides and polyols) intake has substantial effects on gut microbiota. This study aimed to investigate effects of altering FODMAP intake on markers of colonic health in patients with Crohn's disease. After evaluation of their habitual diet, 9 patients with clinically quiescent Crohn's disease were randomised to 21 days of provided low or typical ("Australian") FODMAP diets with ≥21-day washout in between. Five-day fecal samples were collected at the end of each diet and analyzed for calprotectin, pH, short-chain fatty acids (SCFA) and bacterial abundance. Gastrointestinal symptoms were recorded daily. Eight participants collected feces and were adherent to the diets. FODMAP intake differed across the three dietary periods with lowFODMAP diet. Results during habitual diet were similar to the low FODMAP intervention, but significantly different to the Australian diet. The diets had no effects on calprotectin, but symptoms doubled in severity with the Australian diet (n=9; PFODMAP intake is associated with marked changes in fecal microbiota, most consistent with a prebiotic effect of increasing FODMAPs as shown in an irritable bowel/healthy cohort. This strategy might be favorable for gut health in Crohn's disease, but at the cost of inducing symptoms.

  7. Development of the first well-defined tungsten oxo alkyl derivatives supported on silica by SOMC: towards a model of WO3/SiO2 olefin metathesis catalyst

    KAUST Repository

    Mazoyer, Etienne


    A well-defined, silica-supported tungsten oxo alkyl species prepared by the surface organometallic chemistry approach displays high and sustained activity in propene metathesis. Remarkably, its catalytic performances outpace those of the parent imido derivative, underlining the importance of the oxo ligand in the design of robust catalysts. © 2010 The Royal Society of Chemistry.

  8. Synthesis of Well-Defined Copper "N"-Heterocyclic Carbene Complexes and Their Use as Catalysts for a "Click Reaction": A Multistep Experiment that Emphasizes the Role of Catalysis in Green Chemistry (United States)

    Ison, Elon A.; Ison, Ana


    A multistep experiment for an advanced synthesis lab course that incorporates topics in organic-inorganic synthesis and catalysis and highlights green chemistry principles was developed. Students synthesized two "N"-heterocyclic carbene ligands, used them to prepare two well-defined copper(I) complexes and subsequently utilized the complexes as…

  9. Striking difference between alkane and olefin metathesis using the well-defined precursor [≡Si-O-WMe5]: Indirect evidence in favour of a bifunctional catalyst W alkylidene-hydride

    KAUST Repository

    Riache, Nassima


    Metathesis of linear alkanes catalyzed by the well-defined precursor (≡Si-O-WMe5) affords a wide distribution of linear alkanes from methane up to triacontane. Olefin metathesis using the same catalyst and under the same reaction conditions gives a very striking different distribution of linear α-olefins and internal olefins. This shows that olefin and alkane metathesis processes occur via very different pathways.

  10. [(≢SiO)TaVCl2Me2]: A well-defined silica-supported tantalum(V) surface complex as catalyst precursor for the selective cocatalyst-free trimerization of ethylene

    KAUST Repository

    Chen, Yin


    On the surface of it: In the absence of co-catalyst, a well-defined silica-supported surface organometallic complex [(≢SiO)Ta VCl2Me2] selectively catalyzes the oligomerization of ethylene. The use of surface organometallic species allows three different pathways to be determined for the reduction of TaV to TaIII species under pressure of ethylene. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Química organometálica de superfície aplicada à preparação de catalisadores heterogêneos bem definidos Surface organometallic chemistry applied to the preparation of well defined heterogeneous catalysts

    Directory of Open Access Journals (Sweden)

    Silvana I. Wolke


    Full Text Available The study of the reactions of organometallic complexes with the surfaces of inorganic oxides, zeolites and metals constitutes the basis of Surface Organometallic Chemistry (SOMC. The basic rules of organometallic chemistry are often valid when applied to surfaces and well-defined surface organometallic complexes can be obtained. These complexes can be used as heterogeneous catalysts or, by controlled reactions, can be transformed in other species useful for a given catalytic reaction. In some cases, these catalysts exhibit higher activity and/or selectivity than their analogous molecular complexes.

  12. WMe6 tamed by silica: Si-O-WMe5 as an efficient, well-defined species for alkane metathesis, leading to the observation of a supported W-methyl/methylidyne species

    KAUST Repository

    Samantaray, Manoja


    The synthesis and full characterization of a well-defined silica-supported ≡Si-O-W(Me)5 species is reported. Under an inert atmosphere, it is a stable material at moderate temperature, whereas the homoleptic parent complex decomposes above -20 °C, demonstrating the stabilizing effect of immobilization of the molecular complex. Above 70 °C the grafted complex converts into the two methylidyne surface complexes [(≡SiO-)W(≡CH) Me2] and [(≡SiO-)2W(≡CH)Me]. All of these silica-supported complexes are active precursors for propane metathesis reactions. © 2013 American Chemical Society.

  13. Alkane metathesis with the tantalum methylidene [(≡SiO)Ta(=CH2)Me2]/[(≡SiO)2Ta(=CH2)Me] generated from well-defined surface organometallic complex [(≡SiO)TaVMe4

    KAUST Repository

    Chen, Yin


    By grafting TaMe5 on Aerosil700, a stable, well-defined, silica-supported tetramethyl tantalum(V) complex, [(≡SiO)TaMe4], is obtained on the silica surface. After thermal treatment at 150 °C, the complex is transformed into two surface tantalum methylidenes, [(≡SiO)2Ta(=CH2)Me] and [(≡SiO)Ta(=CH2)Me2], which are active in alkane metathesis and comparable to the previously reported [(≡SiO)2TaHx]. Here we present the first experimental study to isolate and identify a surface tantalum carbene as the intermediate in alkane metathesis. A systematic experimental study reveals a new reasonable pathway for this reaction.

  14. Structure-specific adipogenic capacity of novel, well-defined ternary Zn(II)-Schiff base materials. Biomolecular correlations in zinc-induced differentiation of 3T3-L1 pre-adipocytes to adipocytes. (United States)

    Tsave, O; Halevas, E; Yavropoulou, M P; Kosmidis Papadimitriou, A; Yovos, J G; Hatzidimitriou, A; Gabriel, C; Psycharis, V; Salifoglou, A


    Among the various roles of zinc discovered to date, its exogenous activity as an insulin mimetic agent stands as a contemporary challenge currently under investigation and a goal to pursue in the form of a metallodrug against type 2 Diabetes Mellitus. Poised to investigate the adipogenic potential of Zn(II) and appropriately configure its coordination sphere into well-defined anti-diabetic forms, (a) a series of new well-defined ternary dinuclear Zn(II)-L (L=Schiff base ligands with a variable number of alcoholic moieties) compounds were synthesized and physicochemically characterized, (b) their cytotoxicity and migration effect(s) in both pre- and mature adipocytes were assessed, (c) their ability to effectively induce cell differentiation of 3T3-L1 pre-adipocytes into mature adipocytes was established, and (d) closely linked molecular targets involving or influenced by the specific Zn(II) forms were perused through molecular biological techniques, cumulatively delineating factors involved in Zn(II)-induced adipogenesis. Collectively, the results (a) reveal the significance of key structural features of Schiff ligands coordinated to Zn(II), thereby influencing its (a)toxicity behavior and insulin-like activity, (b) project molecular targets influenced by the specific forms of Zn(II) formulating its adipogenic potential, and (c) exemplify the interwoven relationship between Zn(II)-L structural speciation and insulin mimetic biological activity, thereby suggesting ways of fine tuning structure-specific zinc-induced adipogenicity in future efficient antidiabetic drugs. Copyright © 2015 Elsevier Inc. All rights reserved.

  15. Well-Defined Surface Species [(≡Si - O -)W(=O)Me3] Prepared by Direct Methylation of [(≡Si - O -)W(=O)Cl3], a Catalyst for Cycloalkane Metathesis and Transformation of Ethylene to Propylene

    KAUST Repository

    Hamieh, Ali Imad Ali


    The silica-supported tungsten oxo-trimethyl complex [(≡Si - O -)W(=O)Me3] was synthesized using a novel SOMC synthetic approach. By grafting the inexpensive stable compound WOCl4 on the surface of silica, partially dehydroxylated at 700 °C (SiO2-700), a well-defined monopodal surface complex [(≡Si - O -)W(=O)Cl3] was produced. The supported complex directly methylated with ZnMe2 and transformed into [(≡Si - O -)W(=O)Me3], which we fully characterized by microanalysis, IR, mass balance and SS NMR (1H, 13C, 1H-13C HETCOR, 1H-1H DQ and TQ). [(≡Si - O)W(=O)Me3] has two conformational isomers on the surface at room temperature. The conversion of one to the other was observed at 318 K by variable-temperature 13C CP/MAS and 1H spin echo MAS solid-state NMR; this was also confirmed by NMR and DFT calculations. [(≡Si - O)W(=O)Me3] was found to be active in cyclooctane metathesis and to have a wide distribution range in ring-contracted and ring-expanded products. In addition, [(≡Si - O)W(=O)Me3] proved to be highly active for selective transformation of ethylene to propylene compared to other silica-supported organometallic complexes. (Chemical Equation Presented). © 2015 American Chemical Society.

  16. Room temperature one-step synthesis of microarrays of N-doped flower-like anatase TiO2 composed of well-defined multilayer nanoflakes by Ti anodization (United States)

    Wang, Chenglin; Wang, Mengye; Xie, Kunpeng; Wu, Qi; Sun, Lan; Lin, Zhiqun; Lin, Changjian


    Microarrays of N-doped flower-like TiO2 composed of well-defined multilayer nanoflakes were synthesized at room temperature by electrochemical anodization of Ti in NH4F aqueous solution. The TiO2 flowers were of good anatase crystallinity. The effects of anodizing time, applied voltage and NH4F concentration on the flower-like morphology were systematically examined. It was found that the morphologies of the anodized Ti were related to the anodizing time and NH4F concentration. The size and density of the TiO2 flowers could be tuned by changing the applied voltage. The obtained N-doped flower-like TiO2 microarrays exhibited intense absorption in wavelengths ranging from 320 to 800 nm. Under both UV and visible light irradiation, the photocatalytic activity of the N-doped flower-like TiO2 microarrays in the oxidation of methyl orange showed a significant increase compared with that of commercial P25 TiO2 film.

  17. Synthesis and characterization of novel liquid-crystalline azo-dyes bearing two amino-nitro substituted azobenzene units and a well-defined, oligo(ethylene glycol) spacer

    Energy Technology Data Exchange (ETDEWEB)

    Caicedo, Carolina [Instituto de Investigaciones en Materiales, Universidad Nacional Autonoma de Mexico, Circuito Exterior, Ciudad Universitaria, C.P. 04510 Mexico D.F. (Mexico); Rivera, Ernesto, E-mail: [Instituto de Investigaciones en Materiales, Universidad Nacional Autonoma de Mexico, Circuito Exterior, Ciudad Universitaria, C.P. 04510 Mexico D.F. (Mexico); Valdez-Hernandez, Yazmin; Carreon-Castro, Maria del Pilar [Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico, Circuito Exterior, Ciudad Universitaria, C.P. 04510 Mexico D.F. (Mexico)


    Highlights: {yields} Novel dyes containing azobenzene and oligo(ethylene glycol) were synthesized. {yields} Absorption spectra of RED-PEG dyes in CHCl{sub 3} showed {lambda}{sub max} = 440-480 nm. {yields} Absorption spectra of RED-PEG dyes in film revealed the formation of H-aggregates. {yields} Their liquid-crystalline behaviour was confirmed by light polarized microscopy. {yields} These liquid-crystalline dyes can form Langmuir films on the air-water interface. - Abstract: Four novel liquid-crystalline azo-dyes bearing two amino-nitro substituted azobenzene units linked by a well-defined oligo(ethylene glycol) spacer (DIRED-PEG series): (E)-N,N'-(2,2'-oxybis(ethane-2,1-diyl))bis(N-methyl-4-((E)-(4-nitrophenyl) diazenyl) benzenamine) (DIRED-PEG-2), (E)-N,N'-(2,2'-(ethane-1,2-diylbis(oxy)) bis(ethane-2,1-diyl)) bis(N-methyl-4-((E)-(4-nitrophenyl) diazenyl) benzenamine) (DIRED-PEG-3), (E)-N,N'-(2,2'-(2,2'-oxybis (ethane-2,1-diyl) bis(oxy)) bis(ethane-2,1-diyl)) bis(N-methyl-4-((E)-(4-nitrophenyl) diazenyl) benzenamine) (DIRED-PEG-4) and N1,N17-dimethyl-N1,N17-bis (4-((E)-(4-nitrophenyl) diazenyl) phenyl)-3,6,9,12,15-pentaoxaheptadecane-1,17-diamine (DIRED-PEG-6) have been synthesized. These dyes were fully characterized by FTIR, {sup 1}H and {sup 13}C NMR spectroscopies, and their thermal and optical properties were studied. Besides, the liquid-crystalline behaviour of these compounds was monitored in function of the temperature by light polarized microscopy. Finally, Langmuir films were prepared with these dyes.

  18. Well-defined critical association concentration and rapid adsorption at the air/water interface of a short amphiphilic polymer, amphipol A8-35: a study by Förster resonance energy transfer and dynamic surface tension measurements. (United States)

    Giusti, Fabrice; Popot, Jean-Luc; Tribet, Christophe


    Amphipols (APols) are short amphiphilic polymers designed to handle membrane proteins (MPs) in aqueous solutions as an alternative to small surfactants (detergents). APols adsorb onto the transmembrane, hydrophobic surface of MPs, forming small, water-soluble complexes, in which the protein is biochemically stabilized. At variance with MP/detergent complexes, MP/APol ones remain stable even at extreme dilutions. Pure APol solutions self-associate into well-defined micelle-like globules comprising a few APol molecules, a rather unusual behavior for amphiphilic polymers, which typically form ill-defined assemblies. The best characterized APol to date, A8-35, is a random copolymer of acrylic acid, isopropylacrylamide, and octylacrylamide. In the present work, the concentration threshold for self-association of A8-35 in salty buffer (NaCl 100 mM, Tris/HCl 20 mM, pH 8.0) has been studied by Förster resonance energy transfer (FRET) measurements and tensiometry. In a 1:1 mol/mol mixture of APols grafted with either rhodamine or 7-nitro-1,2,3-benzoxadiazole, the FRET signal as a function of A8-35 concentration is essentially zero below a threshold concentration of 0.002 g·L(-1) and increases linearly with concentration above this threshold. This indicates that assembly takes place in a narrow concentration interval around 0.002 g·L(-1). Surface tension measurements decreases regularly with concentration until a threshold of ca. 0.004 g·L(-1), beyond which it reaches a plateau at ca. 30 mN·m(-1). Within experimental uncertainties, the two techniques thus yield a comparable estimate of the critical self-assembly concentration. The kinetics of variation of the surface tension was analyzed by dynamic surface tension measurements in the time window 10 ms-100 s. The rate of surface tension decrease was similar in solutions of A8-35 and of the anionic surfactant sodium dodecylsulfate when both compounds were at a similar molar concentration of n-alkyl moieties. Overall, the

  19. Construction of a well-defined multifunctional dendrimer for theranostics. (United States)

    Ornelas, Cátia; Pennell, Ryan; Liebes, Leonard F; Weck, Marcus


    A dendrimer-based building block for theranostics was designed. The multifunctional dendrimer is polyamide-based and contains nine azide termini, nine amine termini, and fifty-four terminal acid groups. Orthogonal functionalization of the multifunctional dendrimer with a near-infrared (NIR) cyanine dye afforded the final dendrimer that shows fluorescence in the NIR region and no toxicity toward T98G human cells. The synthetic strategy described here might be promising for fabricating the next generation of materials for theranostics.

  20. Electron transfer in systems of well-defined geometry

    Energy Technology Data Exchange (ETDEWEB)

    Overfield, R.E.; Kaufmann, K.J.; Wasielewski, M.R.


    Two mesopyropheophorbide macrocycles can be joined via two covalent linkages to produce a cyclophane. It is possible to insert one or two Mg atoms into the cyclophane. The Qy transitions of the macrocycles are nearly orthogonal. The visible absorption spectrum of the monometal cyclophane is nearly a superposition of the spectra of the monomers. Emission from the monometal cyclophane arises primarily from the red most absorbing chromophore. The excited state difference spectrum shows that both macrocycles are excited. Fluorescence lifetimes of the monometal cyclophane decrease with increasing dielectric strength. Changes in the fluorescence and the triplet yield parallel the shortening of the singlet lifetime. Thus the radiative rate is solvent independent. This is in contrast to what one would expect if the emitting state had charge transfer character. Since the fluorescence lifetime is dependent on dielectric, the nonradiative relaxation from the singlet state is due to formation of a radical pair. The decay rate of the postulated radical pair was monitored by observing the kinetics of ground state repopulation. For the geometry of this cyclophane, electron transfer proceeds relatively slowly (k = 3 x 10/sup 9/ sec/sup -1/) in the forward direction. Modeling calculations indicate that the rate of annihilation of the radical pair may decrease as the solvent dielectric decreases.

  1. Method of preparing well-defined polypeptides via rop

    KAUST Repository

    Hadjichristidis, Nikolaos


    A process for living ring-opening polymerization can include exposing an N- carboxyanhydride monomer to an initiator that includes a first primary amine covalently linked to a first electron donor by a first linking group to form a polyamide polymer. The initiator can include a second primary amine, optionally a second electron donor, and optionally a third electron donor.

  2. Well-Defined Microapertures for Ion Channel Biosensors

    NARCIS (Netherlands)

    Halza, Erik; Bro, Tobias Hedegaard; Bilenberg, Brian; Kocer, Armagan


    Gated ion channels are excitable nanopores in biological membranes. They sense and respond to different triggers in nature. The sensory characteristics of these channels can be modified by protein engineering tools and the channels can be functionally reconstituted into synthetic lipid bilayer

  3. Ichthyosis prematurity syndrome: a well-defined congenital ichthyosis subtype

    DEFF Research Database (Denmark)

    Bygum, Anette; Westermark, Per; Brandrup, Flemming


    Ichthyosis prematurity syndrome is a rare syndrome characterized by the clinical triad of premature birth, thick caseous desquamating epidermis, and neonatal asphyxia. We describe two siblings with ichthyosis prematurity syndrome. The index patient was born at gestational week 34. Immediately aft...

  4. Double Swing

    DEFF Research Database (Denmark)

    Clausen, Lisbeth


    There are two main streams of understanding intercultural communication. The “classic” transmission models include the basic elements of communication involved in sending messages from a sender to a receiver. These models enable analysis of all communication elements and effects by focusing...... on sameness in communication. In contrast, Muneo Jay Yoshikawa's “double-swing” model of intercultural communication between the East and West is based on an eastern understanding of dialogue, collaborative communication, and co-creation of meaning. The double-swing model enables an understanding...... of communication as an ongoing encounter where both sender and receiver have mutual respect. It has four modes of communication: the ethnocentric, the dialectic, the control, and the dialogic. Both models have something to offer intercultural communication, but the double-swing model enables a worldview...

  5. Double screening

    Energy Technology Data Exchange (ETDEWEB)

    Gratia, Pierre [Department of Physics, University of Chicago,South Ellis Avenue, Chicago, IL 60637 (United States); Hu, Wayne [Department of Astronomy and Astrophysics, University of Chicago,South Ellis Avenue, Chicago, IL 60637 (United States); Enrico Fermi Institute and Kavli Institute for Cosmological Physics, University of Chicago,South Ellis Avenue, Chicago, IL 60637 (United States); Joyce, Austin [Enrico Fermi Institute and Kavli Institute for Cosmological Physics, University of Chicago,South Ellis Avenue, Chicago, IL 60637 (United States); Ribeiro, Raquel H. [School of Physics and Astronomy, Queen Mary University of London,Mile End Road, London, E1 4NS (United Kingdom)


    Attempts to modify gravity in the infrared typically require a screening mechanism to ensure consistency with local tests of gravity. These screening mechanisms fit into three broad classes; we investigate theories which are capable of exhibiting more than one type of screening. Specifically, we focus on a simple model which exhibits both Vainshtein and kinetic screening. We point out that due to the two characteristic length scales in the problem, the type of screening that dominates depends on the mass of the sourcing object, allowing for different phenomenology at different scales. We consider embedding this double screening phenomenology in a broader cosmological scenario and show that the simplest examples that exhibit double screening are radiatively stable.

  6. Towards weakly constrained double field theory

    Directory of Open Access Journals (Sweden)

    Kanghoon Lee


    Full Text Available We show that it is possible to construct a well-defined effective field theory incorporating string winding modes without using strong constraint in double field theory. We show that X-ray (Radon transform on a torus is well-suited for describing weakly constrained double fields, and any weakly constrained fields are represented as a sum of strongly constrained fields. Using inverse X-ray transform we define a novel binary operation which is compatible with the level matching constraint. Based on this formalism, we construct a consistent gauge transform and gauge invariant action without using strong constraint. We then discuss the relation of our result to the closed string field theory. Our construction suggests that there exists an effective field theory description for massless sector of closed string field theory on a torus in an associative truncation.

  7. Double inflation

    Energy Technology Data Exchange (ETDEWEB)

    Silk, J.; Turner, M.S.


    The Zel'dovich spectrum of adiabatic density perturbations is a generic prediction of inflation. There is increasing evidence that when the spectrum is normalized by observational data on small scales, there is not enough power on large scales to account for the observed large-scale structure in the Universe. Decoupling the spectrum on large and small scales could solve this problem. As a means of decoupling the large and small scales we propose double inflation (i.e., two episodes of inflation). In this scenario the spectrum on large scales is determined by the first episode of inflation and those on small scales by a second episode of inflation. We present three models for such a scenario. By nearly saturating the large angular-scale cosmic microwave anisotropy bound, we can easily account for the observed large-scale structure. We take the perturbations on small scales to be very large, deltarho/rho approx. = 0.1 to 0.01, which results in the production of primordial black holes (PBHs), early formation of structure, reionization of the Universe, and a rich array of astrophysical events. The ..cap omega..-problem is also addressed by our scenario. Allowing the density perturbations produced by the second episode of inflation to be large also lessens the fine-tuning required in the scalar potential and makes reheating much easier. We briefly speculate on the possibility that the second episode of inflation proceeds through the nucleation of bubbles, which today manifest themselves as empty bubbles whose surfaces are covered with galaxies. 37 refs., 1 fig.

  8. Seeing Double (United States)

    Pesic, Peter


    The separateness and connection of individuals is perhaps the central question of human life: What, exactly, is my individuality? To what degree is it unique? To what degree can it be shared, and how? To the many philosophical and literary speculations about these topics over time, modern science has added the curious twist of quantum theory, which requires that the elementary particles of which everything consists have no individuality at all. All aspects of chemistry depend on this lack of individuality, as do many branches of physics. From where, then, does our individuality come? In Seeing Double, Peter Pesic invites readers to explore this intriguing set of questions. He draws on literary and historical examples that open the mind (from Homer to Martin Guerre to Kafka), philosophical analyses that have helped to make our thinking and speech more precise, and scientific work that has enabled us to characterize the phenomena of nature. Though he does not try to be all-inclusive, Pesic presents a broad range of ideas, building toward a specific point of view: that the crux of modern quantum theory is its clash with our ordinary concept of individuality. This represents a departure from the usual understanding of quantum theory. Pesic argues that what is bizarre about quantum theory becomes more intelligible as we reconsider what we mean by individuality and identity in ordinary experience. In turn, quantum identity opens a new perspective on us. Peter Pesic is a Tutor and Musician-in-Residence at St. John's College, Santa Fe, New Mexico. He has a Ph.D. in physics from Stanford University.

  9. Double hard scattering without double counting (United States)

    Diehl, Markus; Gaunt, Jonathan R.; Schönwald, Kay


    Double parton scattering in proton-proton collisions includes kinematic regions in which two partons inside a proton originate from the perturbative splitting of a single parton. This leads to a double counting problem between single and double hard scattering. We present a solution to this problem, which allows for the definition of double parton distributions as operator matrix elements in a proton, and which can be used at higher orders in perturbation theory. We show how the evaluation of double hard scattering in this framework can provide a rough estimate for the size of the higher-order contributions to single hard scattering that are affected by double counting. In a numeric study, we identify situations in which these higher-order contributions must be explicitly calculated and included if one wants to attain an accuracy at which double hard scattering becomes relevant, and other situations where such contributions may be neglected.

  10. Double hard scattering without double counting

    Energy Technology Data Exchange (ETDEWEB)

    Diehl, Markus [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Gaunt, Jonathan R. [VU Univ. Amsterdam (Netherlands). NIKHEF Theory Group; Schoenwald, Kay [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany)


    Double parton scattering in proton-proton collisions includes kinematic regions in which two partons inside a proton originate from the perturbative splitting of a single parton. This leads to a double counting problem between single and double hard scattering. We present a solution to this problem, which allows for the definition of double parton distributions as operator matrix elements in a proton, and which can be used at higher orders in perturbation theory. We show how the evaluation of double hard scattering in this framework can provide a rough estimate for the size of the higher-order contributions to single hard scattering that are affected by double counting. In a numeric study, we identify situations in which these higher-order contributions must be explicitly calculated and included if one wants to attain an accuracy at which double hard scattering becomes relevant, and other situations where such contributions may be neglected.

  11. The use of double-balloon enteroscopy in retrieving mucosal biopsies from the entire human gastrointestinal tract

    DEFF Research Database (Denmark)

    Rhee, Nicolai Alexander; Vilmann, Peter; Hassan, Hazem


    OBJECTIVE: The aim of this explorative study was to evaluate double-balloon enteroscopy (DBE) as a new tool for collecting mucosal biopsies from well-defined parts of the entire small and large bowel in patients with type 2 diabetes and in matched healthy subjects. MATERIAL AND METHODS: Twelve...

  12. Double outlet right ventricle (United States)

    ... Double outlet right ventricle To use the sharing features on this page, please enable JavaScript. Double outlet right ventricle (DORV) is a heart disease that is ...

  13. Double Outlet Right Ventricle (United States)

    ... Right Ventricle Menu Topics Topics FAQs Double Outlet Right Ventricle Double outlet right ventricle (DORV) is a rare form of congenital heart disease. Article Info En español Double outlet right ventricle (DORV) is a rare form of congenital ...

  14. A fluorescence-based double retrograde tracer strategy for charting central neuronal connections. (United States)

    Apps, Richard; Ruigrok, Tom J H


    Microspheres (beads) tagged with different fluorescent markers can be used for double retrograde axonal tracing of CNS connections. They have several advantages over other double tracer techniques, including ease-of-use, high transport efficiency, distinctive cell labeling and the ability to produce well-defined injection sites. In this protocol we describe the basic procedure for their use, some common problems and how these can be overcome. The protocol, including animal surgery, preparation and delivery of tracer can be completed in approximately 0.5 d. Subsequent histological processing (excluding survival time) can be completed in 0.5-1 d.

  15. Synthesis and characterization of laurate-intercalated Mg–Al layered double hydroxide prepared by coprecipitation

    DEFF Research Database (Denmark)

    Gerds, Nathalie Christiane; Katiyar, Vimal; Koch, Christian Bender


    Effective utilization of layered double hydroxides (LDH) for industrial applications requires the synthesis of pure and well-defined LDH phases. In the present study, dodecanoate (laurate) anions were intercalated into Mg–Al-layered double hydroxide (LDH-C12) by coprecipitation in the presence...... intercalated structure, but we here demonstrate it to be magnesium laurate (Mg-C12). The LDH-C12 compound showed high structural order with a basal spacing of 2.41nm. Fourier-transform IR-spectra confirmed the intercalation of the laurate anions in the interlayer. Transmission electron microscopy showed plate...

  16. The double identity of linguistic doubling. (United States)

    Berent, Iris; Bat-El, Outi; Brentari, Diane; Dupuis, Amanda; Vaknin-Nusbaum, Vered


    Does knowledge of language consist of abstract principles, or is it fully embodied in the sensorimotor system? To address this question, we investigate the double identity of doubling (e.g., slaflaf, or generally, XX; where X stands for a phonological constituent). Across languages, doubling is known to elicit conflicting preferences at different levels of linguistic analysis (phonology vs. morphology). Here, we show that these preferences are active in the brains of individual speakers, and they are demonstrably distinct from sensorimotor pressures. We first demonstrate that doubling in novel English words elicits divergent percepts: Viewed as meaningless (phonological) forms, doubling is disliked (e.g., slaflaf Language, and their capacity to do so depends on the structure of their spoken language (English vs. Hebrew). These results demonstrate that linguistic preferences doubly dissociate from sensorimotor demands: A single stimulus can elicit diverse percepts, yet these percepts are invariant across stimulus modality--for speech and signs. These conclusions are in line with the possibility that some linguistic principles are abstract, and they apply broadly across language modality.

  17. Project Half Double

    DEFF Research Database (Denmark)

    Svejvig, Per; Ehlers, Michael; Adland, Karoline Thorp

    activities carried out within the framework of the projects. The formal part of Project Half Double was initiated in June 2015. We started out by developing, refining and testing the Half Double methodology on seven pilot projects in the first phase of the project, which will end June 2016. The current...... many of the key performance indicators associated with them can be evaluated (Grundfos and Siemens Wind Power). In addition to the current status of delivering impact faster for the seven pilot projects, it is important to highlight that Project Half Double phase 1 has planted many seeds in the pilot...... organisations concerning project methodology and beyond. The many learning points from each pilot project show that Project Half Double has left its clear footprint in the pilot organisations, and that the Half Double methodology has evolved and developed very much during Project Half Double phase 1....

  18. Double sequence core theorems

    Directory of Open Access Journals (Sweden)

    Richard F. Patterson


    Full Text Available In 1900, Pringsheim gave a definition of the convergence of double sequences. In this paper, that notion is extended by presenting definitions for the limit inferior and limit superior of double sequences. Also the core of a double sequence is defined. By using these definitions and the notion of regularity for 4-dimensional matrices, extensions, and variations of the Knopp Core theorem are proved.

  19. Internal Gravity Wave Interactions with Double-Diffusive Instabilities (United States)

    Brown, Justin; Radko, Timour


    In this study, we focus on the phenomenon of oscillatory double-diffusive convection, which occurs when cool fresh water is stratified above warm salty water, as commonly observed in the Arctic Ocean. In the Arctic, these regions are generally stable to the development of oscillatory double-diffusive instabilities; despite this, observations show the presence of staircases, i.e., the well-defined structures consisting of a series of homogeneous layers separated by thin high-gradient interfaces. Recent studies have shown that an instability can develop in such circumstances if weak static shear is present even when the shear and double-diffusion are themselves individually stable. However, the impact of oscillating shear, associated with the ubiquitous presence of internal gravity waves, has not yet been addressed for the diffusive case. Through two-dimensional simulations of diffusive convection, we have investigated the impact of magnitude and frequency of externally forced internal waves on the double-diffusive shear instability. The analysis is focused on the parameter regime in which the flow is individually stable with respect to double-diffusion and Kelvin-Helmholtz instabilities, but could be susceptible to the combined thermohaline-shear instability. We have illustrated that rapid oscillation inhibits the development of this instability if the dominant period is shorter than four hours for the oceanographically relevant parameters; otherwise, models with static shear adequately reproduce our results. If the dominant period is shorter than four hours but still significantly exceeds the buoyancy period, the instability range is much reduced to the low Richardson number regime. Some of these simulations show the saturated system developing into structures reminiscent of double-diffusive staircases whose thickness is given by the wavelength of the forced shear. Finally, preliminary three-dimensional simulations show no major differences in the growth rate of

  20. Neutrinoless double beta decay

    Indian Academy of Sciences (India)


    Oct 6, 2012 ... The physics potential of neutrinoless double beta decay is discussed. Furthermore, experimental considerations as well as the current status of experiments are presented. Finally, an outlook towards the future, work on nuclear matrix elements and alternative processes is given. Keywords. Double beta ...

  1. Congenital maxillary double lip

    Directory of Open Access Journals (Sweden)

    Dinesh Singh Chauhan


    Full Text Available Double lip, also referred to as "macrocheilia," is a rare anomaly which affects the upper lip more commonly than the lower lip. It consists of a fold of excess or redundant hypertrophic tissue on the mucosal side of the lip. The congenital double lip is believed to be present at birth and becomes more prominent after eruption of teeth. It affects esthetics and also interferes with speech and mastication. Simple surgical excision produces good functional and cosmetic results. We report a case of a non-syndromic congenital maxillary double lip in a 21-year-old male patient.

  2. Formation of Double Neutron Stars, Millisecond Pulsars and Double ...

    Indian Academy of Sciences (India)

    Edward P. J. Heuvel


    Sep 12, 2017 ... the double neutron stars and of double black holes is given. 2. Double neutron stars and millisecond pulsars. 2.1 Double neutron stars. In the period 1978 to 1980, Srinivasan and van den. Heuvel profoundly discussed the possible ways in which the Hulse–Taylor binary pulsar could have been formed.

  3. John Deakin: Double Exposures

    Directory of Open Access Journals (Sweden)

    Paul Rousseau


    Full Text Available In this series of short films made by Jonathan Law, the art historian James Boaden, and the curator of The John Deakin Archive, Paul Rousseau, discuss the double-exposure images made by the photographer John Deakin (1912-1972 in the 1950s and 1960s. The films ask you, firstly, to look closely at the images being discussed. Each one begins with a sustained and intense shot of a single image before opening up to a wide-ranging discussion about Deakin, double exposures, and photography.

  4. Double arch mirror study (United States)

    Vukobratovich, D.; Hillman, D.


    The development of a method of mounting light weight glass mirrors for astronomical telescopes compatible with the goals of the Shuttle Infrared Telescope Facility (SIRTF) was investigated. A 20 in. diameter double arch lightweight mirror previously fabricated was modified to use a new mount configuration. This mount concept was developed and fabricated. The mounting concept of the double mounting mirror is outlined. The modifications made to the mirror, fabrication of the mirror mount, and room temperature testing of the mirror and mount and the extension of the mirror and mount concept to a full size (40 in. diameter) primary mirror for SIRTF are discussed.

  5. Double-Barred Galaxies


    Erwin, Peter


    I present a brief review of what is known about double-barred galaxies, where a small ("inner") bar is nested inside a larger ("outer") bar; the review is focused primarily on their demographics and photometric properties. Roughly 20% of S0--Sb galaxies are double-barred; they may be rarer in later Hubble types. Inner bars are typically ~ 500 pc in radius (~ 12% the size of outer bars), but sizes range from ~ 100 pc to > 1 kpc. The structure of at least some inner bars appears very similar to...

  6. Effective light coupling in reflective fiber optic distance sensors using a double-clad fiber (United States)

    Werzinger, Stefan; Härteis, Lisa; Köhler, Aaron; Engelbrecht, Rainer; Schmauss, Bernhard


    Many fiber optic distance sensors use a reflective configuration, where a light beam is launched from an optical fiber, reflected from a target and coupled back into the fiber. While singlemode fibers (SMF) provide low-loss, high-performance components and a well-defined output beam, the coupling of the reflected light into the SMF is very sensitive to mechanical misalignments and scattering at the reflecting target. In this paper we use a double-clad fiber (DCF) and a DCF coupler to obtain an enhanced multimodal coupling of reflected light into the fiber. Increased power levels and robustness are achieved compared to a pure SMF configuration.

  7. Double threshold behavior in a resonance-controlled ZnO random laser

    Directory of Open Access Journals (Sweden)

    Ryo Niyuki


    Full Text Available We observed unusual lasing characteristics, such as double thresholds and blue-shift of lasing peak, in a resonance-controlled ZnO random laser. From the analysis of lasing threshold carrier density, we found that the lasing at 1st and 2nd thresholds possibly arises from different mechanisms; the lasing at 1st threshold involves exciton recombination, whereas the lasing at 2nd threshold is caused by electron-hole plasma recombination, which is the typical origin of conventional random lasers. These phenomena are very similar to the transition from polariton lasing to photon lasing observed in a well-defined cavity laser.

  8. Aristotle and Double Effect

    DEFF Research Database (Denmark)

    Di Nucci, Ezio


    There are some interesting similarities between Aristotle’s ‘mixed actions’ in Book III of the Nicomachean Ethics and the actions often thought to be justifiable with the Doctrine of Double Effect. Here I analyse these similarities by comparing Aristotle’s examples of mixed actions with standard ...

  9. Neutrinoless double beta decay

    Indian Academy of Sciences (India)


    Nov 27, 2015 ... Abstract. The physics potential of neutrinoless double beta decay is discussed. Furthermore, experimental considerations as well as the current status of experiments are presented. Finally, an outlook towards the future, work on nuclear matrix elements and alternative processes is given.

  10. Double-Glazing Interferometry (United States)

    Toal, Vincent; Mihaylova, Emilia M.


    This note describes how white light interference fringes can be seen by observing the Moon through a double-glazed window. White light interferometric fringes are normally observed only in a well-aligned interferometer whose optical path difference is less than the coherence length of the light source, which is approximately one micrometer for…

  11. Double beta decay

    Energy Technology Data Exchange (ETDEWEB)

    Bryman, D.; Picciotto, C.


    The problem of double beta decay is reviewed with emphasis on its relevance to lepton number conservation. Recently, the ratio of the double beta-decay half-lives of /sup 128/Te and /sup 130/Te has been measured in a geological experiment and a limit for the ratio of the neutrinoless rate to the total rate for /sup 82/Se decay has been obtained from a direct-detection experiment. For the first time, these results show conclusively that double beta decay is not primarily a lepton-number-violating neutrinoless process. However, they also do not agree with calculations which assume that only lepton-number-conserving two-neutrino double beta decay occurs. The conclusion that lepton number conservation is violated is suggested by limited experimental information. By considering contributions to the total rate from both the two-neutrino and the neutrinoless channels, we obtain data which are consistent with a lepton nonconservation parameter of order eta=3.5 x 10/sup -5/. Roughly the same value of eta is obtained by assuming that the decay occurs either via lepton emission from two nucleons or via emission from a resonance in the nucleus.

  12. Design for Double Rainbow (United States)

    Thomas, Lisa Carlucci


    Rare is the inspirational, spontaneous, transformative moment shared among 20 million people. In the summer of 2010, people around the world were moved by the sighting of a double rainbow--almost a triple rainbow--"all the way across the sky" in Yosemite National Park. Caught on video and posted to by YouTube by Paul Vasquez in January 2010, the…

  13. Generalizing double graphs

    Directory of Open Access Journals (Sweden)

    Zagaglia Salvi, Norma


    Full Text Available In this paper we study the graphs which are direct product of a simple graph G with the graphs obtained by the complete graph Kk adding a loop to each vertex; thus these graphs turn out to be a generalization of the double graphs.

  14. Hybrid Double Quantum Dots

    DEFF Research Database (Denmark)

    Sherman, D.; Yodh, J. S.; Albrecht, S. M.


    Epitaxial semiconductor-superconductor hybrid materials are an excellent basis for studying mesoscopic and topological superconductivity, as the semiconductor inherits a hard superconducting gap while retaining tunable carrier density. Here, we investigate double-quantum-dot devices made from InA...... that the individual dots host weakly hybridized Majorana modes....

  15. Well-Defined Molecular Magnesium Hydride Clusters : Relationship between Size and Hydrogen-Elimination Temperature

    NARCIS (Netherlands)

    Intemann, Julia; Spielmann, Jan; Sirsch, Peter; Harder, Sjoerd

    A new tetranuclear magnesium hydride cluster, [{NN-(MgH)2}2], which was based on a NN-coupled bis--diketiminate ligand (NN2-), was obtained from the reaction of [{NN-(MgnBu)2}2] with PhSiH3. Its crystal structure reveals an almost-tetrahedral arrangement of Mg atoms and two different sets of hydride

  16. “Social Media as Multipliers in Nation Branding provided it has a Well Defined Strategy”

    Directory of Open Access Journals (Sweden)

    Manuel Santillán-Vásquez


    Full Text Available Villafañe has conducted the first study of Spain’s Country Brand from the Theory of Reputation perspective. According to the author branding is the promise that a company or a country makes to its stakeholders. Villafañe proposes a scientific and professional approach on building a Country Brand and seeks to identify thoroughly the branding promise to then compare it with the identity of a nation. The study delves into the proposition of value and links it to the expectations and interests of diverse stakeholders. This interview intends to assess carefully some key aspects of its methodology.

  17. A method to obtain a well-defined fraction of respirable para-aramid fibers. (United States)

    Schins, R P; Gaudichet, A; Jaurand, M C


    We developed a preparation method to obtain respirable-sized fractions of para-aramid fibers. The procedure, based on floatability, consists of stirring and subsequent settling of p-aramid pulp in distilled water. Two distinct phases are obtained, with small fibers in the upper part of the suspension, which represents about 33% of the total volume. Optimal results were obtained when 2.0 g pulp was stirred for 15 hr in 800 ml distilled water containing 0.125% ethanol and settled for 5 hr. The mass yield ranged between 0.4 and 0.6%, more than 90% of the particles had an aspect ratio > or = 3:1. The mean fiber length was about 6 microns, and the mean fiber diameter was about 0.4 microns as determined by transmission and scanning electron microscopy. The number of fibers obtained was 4 x 10(6) fibers/micrograms under our standard conditions.

  18. Preparation of well-defined samples of AlPdMn quasicrystals for surface studies (United States)

    Jenks, C. J.; Delaney, D. W.; Bloomer, T. E.; Chang, S.-L.; Lograsso, T. A.; Shen, Z.; Zhang, C.-M.; Thiel, P. A.


    We have developed a method for preparing single-grain, quasicrystalline AlPdMn samples for surface studies in ultrahigh vacuum. The main issues of concern are phase purity, the quality of the surface structure, and the surface, and the surface composition. Phase purity is enhanced by annealing the sample in ultra-pure Ar in a sealed quartz ampoule for several days before polishing. Polishing with colloidal silica allows secondary phases to be detected readily with an optical microscope. As a final precaution, phase purity can be checked sensitively with scanning Auger microscopy. After this stage, the sample can be cleaned in ultrahigh vacuum with ion bombardment. Annealing is required after bombardment to restore surface structure and to obtain a low-energy electron diffraction (LEED) pattern of an oriented sample. However, both ion bombardment and heating to temperatures above 870 K in vacuum, produce Pd-rich surfaces. As a final step, for the five-fold surface, we recommend heating briefly to 1050-1100 K and then annealing at 870 K for several hours. This produces both an excellent LEED pattern, and a surface composition close to that of the bulk.

  19. Mimicking conjugated polymer thin-film photophysics with a well-defined triblock copolymer in solution. (United States)

    Brazard, Johanna; Ono, Robert J; Bielawski, Christopher W; Barbara, Paul F; Vanden Bout, David A


    Conjugated polymers (CPs) are promising materials for use in electronic applications, such as low-cost, easily processed organic photovoltaic (OPV) devices. Improving OPV efficiencies is hindered by a lack of a fundamental understanding of the photophysics in CP-based thin films that is complicated by their heterogeneous nanoscale morphologies. Here, we report on a poly(3-hexylthiophene)-block-poly(tert-butyl acrylate)-block-poly(3-hexylthiophene) rod-coil-rod triblock copolymer. In good solvents, this polymer resembles solutions of P3HT; however, upon the addition of a poor solvent, the two P3HT chains within the triblock copolymer collapse, affording a material with electronic spectra identical to those of a thin film of P3HT. Using this new system as a model for thin films of P3HT, we can attribute the low fluorescence quantum yield of films to the presence of a charge-transfer state, providing fundamental insights into the condensed phase photophysics that will help to guide the development of the next generation of materials for OPVs.

  20. Sorption-determined deposition of Platinum on well-defined platelike WO3

    NARCIS (Netherlands)

    Wenderich, Kasper; Klaassen, Aram Harold; Sîretanu, Igor; Mugele, Friedrich Gunther; Mul, Guido


    The photodeposition of Pt nanoparticles from [PtCl6]2− on platelike WO3 crystals occurs preferentially on the small, subordinate facets. Rather than the often-used explanation of preferred light-induced charge migration, we propose that this phenomenon is due to differences in the intrinsic surface

  1. Well-Defined Silica Grafted Molybdenum Bis(imido) Catalysts for Imine Metathesis Reactions

    KAUST Repository

    Barman, Samir


    Novel site-isolated tetracoordinated molybdenum complexes possessing bis(imido) ligands, [(≡Si–O)2Mo(═NR)2] (R = t-Bu, 2,6-C6H3-i-Pr2), were immobilized on partially dehydroxylated silica (SiO2-200) by a rigorous surface organometallic chemistry protocol. The newly developed materials adorned with bis(imido) functional units, which were previously exploited mainly as spectator ligands on silica-supported olefin metathesis molybdenum catalysts, are found to be efficient heterogeneous catalytic systems for imine cross metathesis under mild conditions.

  2. Synthesis of Well-Defined Polyethylene-Based 3-Miktoarm Star Copolymers and Terpolymers

    KAUST Repository

    Zhang, Zhen


    Novel polyethylene (PE)-based 3-miktoarm star copolymers A2B, (AB)2B and terpolymers (AC)2(BC) [A: PE; B, C: polystyrene (PS) or poly(methyl methacrylate) (PMMA)] were synthesized by combining boron chemistry, polyhomologation, and atom transfer radical polymerization (ATRP). 1,4-Pentadiene-3-yl 2-bromo-2-methylpropanoate was first synthesized followed by hydroboration with thexylborane to afford B-thexylboracyclanes, a multi-heterofunctional initiator with two initiating sites for polyhomologation and one for ATRP. After polyhomologation of dimethylsulfoxonium methylide the α,ω-dihydroxyl polyethylene (PE-OH)2-Br produced served as macroinitiator for the ATRP of styrene to afford (PE-OH)2-(PS-Br). Both (PE-OH)2-Br and (PE-OH)2-(PS-Br) were transformed to two new trifunctional macroinitiators (PE-Br)2-Br and (PE-Br)2-(PS-Br) through esterification reactions and used for the synthesis of (AB)2B and (AC)2(BC) 3-miktoarm star co/terpolymers. All intermediates and final products were characterized by 1H NMR, high temperature gel permeation chromatography (HT-GPC), and differential scanning calorimetry (DSC). The synthetic method is a general one and can be used for the synthesis of complex PE-based architectures by combination with other living/living-controlled polymerization techniques. © 2016 American Chemical Society.

  3. Well-defined polyglutamates as carriers for the treatment of neurodegenerative diseases


    Duro Castaño, Aroa


    Alzheimer’s disease (AD) is a neurodegenerative multiple process of the central nervous system, which currently represents the most common cost of Dementia. The already high incidence of AD is predicted to dramatically increase over the years. In fact, the experts claim that it will become a global epidemy by 2050. Consequently, direct and indirect costs related to AD are doomed to dramatically increase. For instance, only in America, AD related burden will overcome the trillion of dollars by...

  4. Biological activity of well defined hydantoin derivatives on efflux pump systems of bacteria and cancer cells


    Evaristo, Miguel do Rosário


    A multi-resistência a antibióticos e medicamentos usados em quimioterapia é um dos grandes problemas com os quais as instituições de saúde se debatem hoje em dia. A acção provocada por bombas de efluxo é uma das suas causas. Estas bombas têm uma importância fundamental, uma vez que, ao expelirem todo o tipo de tóxicos para o exterior das células, também expelem medicamentos, fazendo com que estes não tenham o efeito desejado dentro delas. As bombas de efluxo são transportadores que se enco...

  5. Well-defined single-site monohydride silica-supported zirconium from azazirconacyclopropane

    KAUST Repository

    Hamzaoui, Bilel


    The silica-supported azazirconacyclopropane ≡SiOZr(HNMe2)(η2-NMeCH2)(NMe2) (1) leads exclusively under hydrogenolysis conditions (H2, 150°C) to the single-site monopodal monohydride silica-supported zirconium species ≡SiOZr(HNMe2)(NMe2)2H (2). Reactivity studies by contacting compound 2 with ethylene, hydrogen/ethylene, propene, or hydrogen/propene, at a temperature of 200°C revealed alkene hydrogenation.

  6. A novel method for synthesizing well-defined boehmite hollow microspheres. (United States)

    Xu, Dong; Jiang, Hongyi; Li, Ming


    A novel and effective synthesis route has been developed to fabricate γ-AlOOH (boehmite) hollow microspheres (diameter in 1-2μm) with urchin-like shell structures. The external surface of the hollow microspheres was constructed by randomly aggregated and interconnecting nanoplatelets (length in 50nm). The method involves two processes: (1) solid spherical particles can be obtained by an epoxide-driven sol-gel process in several seconds, (2) solid spheres particles transform into urchin-like hollow spheres through chemically induced self-transformation process. Formation of the γ-AlOOH hollow microspheres was strongly dependent on the amount of propylene oxide, the volume ratio of solvents, as well as the kinds of anion. γ-AlOOH hollow microspheres could only be obtained in a particular situation that AlCl 3 ·6H 2 O acts as salt precursor and the volume between H 2 O and ethanol were defined as 4ml, 6ml and 6ml, 4ml. In general, the described method is efficient and environmentally benign, and has significant advantages over traditional template approaches to the large-scale production of hollow inorganic materials. Copyright © 2017. Published by Elsevier Inc.

  7. Well-defined degradable brush polymer-drug conjugates for sustained delivery of Paclitaxel. (United States)

    Yu, Yun; Chen, Chih-Kuang; Law, Wing-Cheung; Mok, Jorge; Zou, Jiong; Prasad, Paras N; Cheng, Chong


    To achieve a conjugated drug delivery system with high drug loading but minimal long-term side effects, a degradable brush polymer-drug conjugate (BPDC) was synthesized through azide-alkyne click reaction of acetylene-functionalized polylactide (PLA) with azide-functionalized paclitaxel (PTXL) and poly(ethylene glycol) (PEG). Well-controlled structures of the resulting BPDC and its precursors were verified by (1)H NMR and gel permeation chromatography (GPC) characterizations. With nearly quantitative click efficiency, drug loading amount of the BPDC reached 23.2 wt %. Both dynamic light scattering (DLS) analysis and transmission electron microscopy (TEM) imaging indicated that the BPDC had a nanoscopic size around 10-30 nm. The significant hydrolytic degradability of the PLA backbone of the BPDC was confirmed by GPC analysis of its incubated solution. Drug release study showed that PTXL moieties can be released through the cleavage of the hydrolyzable conjugation linkage in pH 7.4 at 37 °C, with 50% release in about 22 h. As illustrated by cytotoxicity study, while the polymeric scaffold of the BPDC is nontoxic, the BPDC exhibited higher therapeutic efficacy toward MCF-7 cancer cells than free PTXL at 0.1 and 1 μg/mL. Using Nile red as encapsulated fluorescence probe, cell uptake study showed effective internalization of the BPDC into the cells.

  8. Prevalence and incidence of epilepsy in a well-defined population of Northern Italy. (United States)

    Giussani, Giorgia; Franchi, Carlotta; Messina, Paolo; Nobili, Alessandro; Beghi, Ettore


    To calculate prevalence and incidence of epilepsy using administrative records. Claim records from the administrative district of Lecco, Northern Italy (population 311,637; 2001 census), collected during the years 2000-2008, were the data source. Patients of all ages were included. Based on previous findings from our group, the most accurate algorithm to detect epilepsy was the combination of electroencephalography (EEG) (ad hoc code) (at least one during the study period) and antiepileptic drugs (AEDs) (ATC code) (taken in 2008). Using this algorithm, the prevalence of epilepsy for the year 2008 was calculated. The reference population for prevalence was the population residing in the study area during the year 2008. Incident epilepsy cases were a subset of prevalent cases among patients not traced in the years 2000 through 2003. Average annual incidence rates were calculated for 2004 through 2008, taking for reference the person-years of exposure in the resident population. We calculated crude, adjusted (using positive and negative predictive values), and standardized (to the Italian and World population) prevalence and incidence. In 2008, 1,504 patients met the inclusion criteria, giving a prevalence of 4.57 per 1,000 (women 4.26; men 4.89). Prevalence tended to rise slightly with age. There were 864 incident cases, giving an average annual incidence of 53.41 per 100,000 (women 50.98; men 55.95). Incidence rates peaked in the elderly. The adjusted prevalence was 4.42 and the adjusted incidence 47.05. Standardized prevalence and incidence were, respectively, 4.30 per 1,000 and 48.35 per 100,000 (Italian population) and 3.79 per 1,000 and 44.74 per 100,000 (World population). The prevalence of epilepsy in the Lecco district was comparable to other studies, whereas the incidence was among the highest. With adjustments, administrative records are a cost-effective instrument to monitor epilepsy frequency. Wiley Periodicals, Inc. © 2014 International League Against Epilepsy.

  9. Well-defined oligosaccharide-terminated polymers from living radical polymerization. (United States)

    Haddleton, D M; Ohno, K


    beta-cyclodextrin has been transformed into an initiator for copper(I)-mediated living radical polymerization via successive acetylation, ring opening, and condensation reactions. This glycoinitiator has been successfully used to prepare a range of methacrylate polymers, which show all characteristics of living polymerization. Poly(methyl methacrylate) is prepared with an Mn of 10,100 g/mol (theoretical Mn = 10,900) and polydispersity of 1.09. Excellent first-order kinetics and an evolution of mass with time are presented. Hydrophilic polymers based on poly(ethylene glycol), glucose and tertiary amine monomers are successfully prepared with terminal maltoheptose units. Polymerization of styrene results in a broadening of the polydispersity to 1.48 while maintaining good control over the Mn. The acetyl protecting groups on the maltoheptose terminal unit are easily removed in all cases to give the hydroxylated sugar, as shown by NMR. These results demonstrate the applicability of utilizing glycoinitiators as a new, versatile route to a wide range of glycopolymers. The polymerization chemistry is inert to the sugar functionality allowing glyco units to be precisely placed within a synthetic macromolecule with all the associated advantages of living polymerization.

  10. Nanorods of Silicon and Germanium with Well-Defined Shapes and Sizes

    Energy Technology Data Exchange (ETDEWEB)

    Slavi C. Sevov


    We have made number of important discoveries along the major goals of the project, namely i) electrodeposition of germanium thin films from clusters, ii) synthesis of cluster-based surfactants with long hydrocarbon chains and micelles made of them, iii) grafting of Ge{sub 9}-clusters onto self assembled films of siloxanes attached to glass substrates, iv) doping of Ge{sub 9}-clusters, and v) expanding the clusters to ten-atom cages of Ge{sub 10}{sup 2-}.

  11. Functionalized Nanoporous Polymer Membranes with Well-Defined Pore Architectures via Lyotropic Liquid-Crystalline Monomers

    National Research Council Canada - National Science Library

    Gin, Douglas


    .... Two lyotropic liquid-crystalline monomer platforms have been synthesized. The interchannel separations in the polymerizable materials can be varied in the 30-40 A range by the choice of counterion on the ionic headgroup of the monomers...

  12. Synthesis of a Novel Family of Polysilsesquioxanes Having Oligothiophenes with Well-Defined Structures

    Directory of Open Access Journals (Sweden)

    Ichiro Imae


    Full Text Available Our recent results on the synthesis and properties of a novel family of polysilsesquioxanes having oligothiophenes were reviewed. The polymers anchored on SiO2 or ITO substrates showed excellent mechanical hardness due to the formation of a three-dimensional siloxane network structure and chemical linkage between polymer and the surface of metal-oxide substrates. Optical, electrochemical, and electrical properties of polymers were also investigated.

  13. From competition to cooperation: A highly efficient strategy towards well-defined (co)polypeptides

    KAUST Repository

    Zhao, Wei


    By associating primary (slow but controlled ring-opening polymerization; ROP) and tertiary (fast but uncontrolled ROP) amines in the same molecule, a novel highly active organocatalytic system proceeding by an accelerated amine mechanism through monomer activation (AAMMA) and leading to living ROP of α-amino acid N-carboxyanhydrides at room temperature was successfully developed. This journal is

  14. Working for wellness: defining, measuring, and enhancing employee well-being


    Page, Kathryn May


    The focus of this thesis was on the utility of the workplace in promoting employee well-being. The thesis applied principles of positive psychology (PP) to the field of occupational health psychology (OHP). Paper 1 reviewed employee well-being with a focus on both general and work-related dimensions. Paper 2 developed a niche for positive employee well-being programs. It reviewed a number of strategies for improving employee health and well-being, including occupational health and safety leg...

  15. Search Engines and Expertise about Global Issues: Well-defined Landscape or Undomesticated Wilderness? (United States)

    Fry, J.; Virkar, S.; Schroeder, R.

    This chapter investigates the `winner-takes-all' hypothesis in relation to how academic researchers access online sources and resources. Some have argued that the Web provides access to a wider range of sources of information than offline resources. Others, such as Hindman et al. (2003), have shown that access to online resources is highly concentrated, particularly because of how Internet search engines are designed. With researchers increasingly using the Web and Internet search engines to disseminate and locate information and expertise, the question of whether the use of online resources enhances or diminishes the range of available sources of expertise is bound to become more pressing. To address this question four globally relevant knowledge domains were investigated using large-scale link analysis and a series of semi-structured interviews with UK-based academic researchers. We found there to be no uniform `winner-takes-all' effect in the use of online resources. Instead, there were different types of information gatekeepers for the four domains we examined and for the types of resources and sources that are sought. Particular characteristics of a knowledge domain's information environment appear to determine whether Google and other Internet search engines function as a facilitator in accessing expertise or as an influential gatekeeper.

  16. The Demand-Control Model: Specific demands, specific Control, and well-defined groups

    NARCIS (Netherlands)

    Jonge, J. de; Dollard, M.F.; Dormann, C.; Blanc, P.M.; Houtman, I.L.D.


    The purpose of this study was to test the Demand-Control Model (DCM), accompanied by three goals. Firstly, we used alternative, more focused, and multifaceted measures of both job demands and job control that are relevant and applicable to today's working contexts. Secondly, this study intended to

  17. Well-defined ABA- and BAB-type block copolymers of PDMAEMA and PCL

    DEFF Research Database (Denmark)

    Bruce, Carl; Javakhishvili, Irakli; Fogelstrom, Linda


    Triblock copolymers of ABA- and BAB-type consisting of poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA, A) and poly(epsilon-caprolactone) (PCL, B) have successfully been prepared. PDMAEMA-b-PCL-b-PDMAEMA (ABA) and PCL-b-PDMAEMA-b-PCL (BAB) were synthesised by a combination of ring...... as the outer block (ABA), the inherent crystallinity of PCL was destroyed while with PCL as the outer block (BAB), the degree of crystallinity was in the same proximity as for a PCL homopolymer....

  18. CO2 Electroreduction on Well-Defined Bimetallic Surfaces

    DEFF Research Database (Denmark)

    Varela Gasque, Ana Sofia; Schlaup, Christian Georg; Jovanov, Zarko P.


    We have studied the electrochemical reduction of CO2 on Cu overlayers on Pt(111) and Pt(211) surfaces. These systems were chosen to investigate the effect of strain on the catalytic activity of Cu surfaces and to obtain information about the role of steps in this process. The selectivity toward h...

  19. Modular synthesis of well-defined macromolecular architectures : employment of 'click' reactions in polymer chemistry

    NARCIS (Netherlands)

    Opsteen, Johannes Antonius


    The copper(I)-catalyzed Huisgen 1,3-dipolar cycloaddition of azides and terminal acetylenes was utilized to modularly syntesize (biohybrid) block copolymers, cyclic polymers and to functionalize the periphery of polymersomes. Therefore, both azide and acetylene functionalized polymer building blocks

  20. Structure and Magnetism of well-defined cobalt nanoparticles embedded in a niobium matrix


    Jamet, M.; Dupuis, V.; Melinon, P.; Perez, A.; Wernsdorfer, W.; Traverse, A.; Baguenard, B.


    Our recent studies on Co-clusters embedded in various matrices reveal that the co-deposition technique (simultaneous deposition of two beams : one for the pre-formed clusters and one for the matrix atoms) is a powerful tool to prepare magnetic nanostructures with any couple of materials even though they are miscible. We study, both sharply related, structure and magnetism of the Co/Nb system. Because such a heterogeneous system needs to be described at different scales, we used microscopic an...

  1. A silica-supported double-decker silsesquioxane provides a second skin for the selective generation of bipodal surface organometallic complexes

    KAUST Repository

    Espinas, Jeff


    A well-defined silica-based material with a homogeneous nanolayer presenting identical pairs of vicinal silanols has been prepared by reaction of the surface organometallic species [≡SiOZr(CH 2CMe 3) 3], obtained on a silica dehydroxylated at 900 °C, with the double-decker-shaped silsesquioxane (OH) 2DD(OH) 2. The surface structure has been established using extensive NMR characterization ( 1H, 13C, 29Si, HETCOR, double-quantum, triple-quantum). Treatment with Zr(CH 2CMe 3) 4 leads to the first well-defined single-site bipodal grafted bis-neopentyl zirconium complex. © 2012 American Chemical Society.

  2. Applications of Diamonded Double Negation


    Yli-Jyrä, Anssi


    Nested complementation plays an important role in expressing counter- i.e. star-free and first-order definable languages and their hierarchies. In addition, methods that compile phonological rules into finite-state networks use double-nested complementation or “double negation”. This paper reviews how the double-nested complementation extends to a relatively new operation, generalized restriction (GR), coined by the author (Yli-Jyrä and Koskenniemi 2004). This operation encapsulates a double-...

  3. Double Cortex Syndrome


    J Gordon Millichap


    The incidence of mutations in the X-linked gene doublecortin in patients with “double cortex” syndrome (DC; also called subcortical band heterotopia or laminar heterotopia) and familial DC with lissencephaly was investigated in a cohort of 8 pedigrees and 47 sporadic patients with DC examined at the Division of Neurogenics, Beth Israel Deaconess Medical Center, Boston, and multiple centers in the US and abroad.

  4. Algebra of Majorana doubling. (United States)

    Lee, Jaehoon; Wilczek, Frank


    Motivated by the problem of identifying Majorana mode operators at junctions, we analyze a basic algebraic structure leading to a doubled spectrum. For general (nonlinear) interactions the emergent mode creation operator is highly nonlinear in the original effective mode operators, and therefore also in the underlying electron creation and destruction operators. This phenomenon could open up new possibilities for controlled dynamical manipulation of the modes. We briefly compare and contrast related issues in the Pfaffian quantum Hall state.

  5. Results of double contrast enema

    Energy Technology Data Exchange (ETDEWEB)

    Czembirek, H.; Sommer, G.; Wittich, G.; Tscholakoff, D.; Salomonowitz, E.


    Experiences and results of double contrast enemas are reported. The accuracy of double contrast enemas is proved by 500 consecutive investigations. Correlation of endoscopic and roentgenologic investigations showed, that the double contrast enema is a reliable method concerning the detection of polyps, carcinomas and inflammatory colon diseases. Advantages and disadvantages of roentgenology and endoscopy of the colon are discussed.

  6. Ac-induced disruption of the doubleDs structure in tomato

    NARCIS (Netherlands)

    Rommens, Caius M.T.; Biezen, Erik A. van der; Ouwerkerk, Pieter B.F.; Nijkamp, H. John J.; Hille, Jacques


    The maize doubleDs element is stably maintained in the tomato genome. Upon the subsequent introduction of Ac into a plant containing doubleDs, disruption of the doubleDs structure and DNA rearrangements at the site of the doubleDs element were observed. No indications were obtained for excision of

  7. Period doubling induced by thermal noise amplification in genetic circuits (United States)

    Ruocco, G.; Fratalocchi, A.


    Rhythms of life are dictated by oscillations, which take place in a wide rage of biological scales. In bacteria, for example, oscillations have been proven to control many fundamental processes, ranging from gene expression to cell divisions. In genetic circuits, oscillations originate from elemental block such as autorepressors and toggle switches, which produce robust and noise-free cycles with well defined frequency. In some circumstances, the oscillation period of biological functions may double, thus generating bistable behaviors whose ultimate origin is at the basis of intense investigations. Motivated by brain studies, we here study an ``elemental'' genetic circuit, where a simple nonlinear process interacts with a noisy environment. In the proposed system, nonlinearity naturally arises from the mechanism of cooperative stability, which regulates the concentration of a protein produced during a transcription process. In this elemental model, bistability results from the coherent amplification of environmental fluctuations due to a stochastic resonance of nonlinear origin. This suggests that the period doubling observed in many biological functions might result from the intrinsic interplay between nonlinearity and thermal noise.

  8. Period doubling induced by thermal noise amplification in genetic circuits

    KAUST Repository

    Ruocco, G.


    Rhythms of life are dictated by oscillations, which take place in a wide rage of biological scales. In bacteria, for example, oscillations have been proven to control many fundamental processes, ranging from gene expression to cell divisions. In genetic circuits, oscillations originate from elemental block such as autorepressors and toggle switches, which produce robust and noise-free cycles with well defined frequency. In some circumstances, the oscillation period of biological functions may double, thus generating bistable behaviors whose ultimate origin is at the basis of intense investigations. Motivated by brain studies, we here study an “elemental” genetic circuit, where a simple nonlinear process interacts with a noisy environment. In the proposed system, nonlinearity naturally arises from the mechanism of cooperative stability, which regulates the concentration of a protein produced during a transcription process. In this elemental model, bistability results from the coherent amplification of environmental fluctuations due to a stochastic resonance of nonlinear origin. This suggests that the period doubling observed in many biological functions might result from the intrinsic interplay between nonlinearity and thermal noise.

  9. Synthesis and carbon dioxide sorption of layered double hydroxide/silica foam nanocomposites with hierarchical mesostructure

    KAUST Repository

    Fu, Liling


    Layered double hydroxides (LDHs) with a hierarchical mesostructure are successfully synthesized on mesoporous silica foams by simple impregnation and hydrothermal treatment. The as-synthesized LDH/silica foam nanocomposites show well-defined mesostructures with high surface areas, large pore volumes, and mesopores of 6-7 nm. The nanocomposites act as carbon dioxide (CO2) sorbents under simulated flue gas conditions. They also exhibit significantly enhanced CO2 capacities under high-pressure conditions and high CO2/N2 and CO2/CH4 selectivities. Respect the hierarchy: Hierarchical mesoporous layered double hydroxide (LDH) nanocomposites with high surface areas and large pore volumes are synthesized by controlled hydrothermal growth of LDH precursors on a mesoporous silica foam. The as-synthesized nanocomposites exhibit a significantly enhanced capacity and selectivity towards carbon dioxide, making them very promising candidates for carbon dioxide (CO2) separation applications. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. The Double Star mission

    Directory of Open Access Journals (Sweden)



    Full Text Available The Double Star Programme (DSP was first proposed by China in March, 1997 at the Fragrant Hill Workshop on Space Science, Beijing, organized by the Chinese Academy of Science. It is the first mission in collaboration between China and ESA. The mission is made of two spacecraft to investigate the magnetospheric global processes and their response to the interplanetary disturbances in conjunction with the Cluster mission. The first spacecraft, TC-1 (Tan Ce means "Explorer", was launched on 29 December 2003, and the second one, TC-2, on 25 July 2004 on board two Chinese Long March 2C rockets. TC-1 was injected in an equatorial orbit of 570x79000 km altitude with a 28° inclination and TC-2 in a polar orbit of 560x38000 km altitude. The orbits have been designed to complement the Cluster mission by maximizing the time when both Cluster and Double Star are in the same scientific regions. The two missions allow simultaneous observations of the Earth magnetosphere from six points in space. To facilitate the comparison of data, half of the Double Star payload is made of spare or duplicates of the Cluster instruments; the other half is made of Chinese instruments. The science operations are coordinated by the Chinese DSP Scientific Operations Centre (DSOC in Beijing and the European Payload Operations Service (EPOS at RAL, UK. The spacecraft and ground segment operations are performed by the DSP Operations and Management Centre (DOMC and DSOC in China, using three ground station, in Beijing, Shanghai and Villafranca.

  11. Layered double hydroxides

    DEFF Research Database (Denmark)

    López Rayo, Sandra; Imran, Ahmad; Hansen, Hans Chr. Bruun


    A novel zinc (Zn) fertilizer concept based on Zn doped layered double hydroxides (Zn-doped Mg-Fe-LDHs) has been investigated. Zn-doped Mg-Fe-LDHs were synthetized, their chemical composition was analyzed and their nutrient release was studied in buffered solutions with different pH values. Uptake...... the long-term Zn release capacity of LDHs complying with a release-on-demand behavior and serves as proof-of-concept that Zn-doped Mg-Fe-LDHs can be used as Zn fertilizers....

  12. Double conjugate laser amplifier

    Energy Technology Data Exchange (ETDEWEB)

    Chandra, S.; Daunt, G.H.


    This paper describes a double conjugate laser amplifier system for producing a stable output laser beam in line with a laser oscillator input beam. It comprises: a laser oscillator which produces a low energy oscillator laser beam therefrom directly along a laser beam axis of the system; an amplification means comprised of double conjugate laser amplifiers further comprised of a first and a second singly phase conjugate amplifiers laterally opposite each other about the laser beam axis; polarizers with one of the polarizers positioned between each of the first and second singly phase conjugate amplifiers on the laser beam axis; Pockels cells with on of the Pockels cells positioned on the laser beam axis immediately prior to one of the polarizers; and a means for selectively switching the amplifier means comprised of applying a half-wave voltage at each of the Pockels cells to provide a polarization rotation of the input beam through 90{degrees} for routing of the oscillator laser beam directly through or reflected off the polarizes as an input beam to the amplification means wherein the amplification means amplifies the input beam twice in each of the first and second singly phase conjugate amplifiers and reflects the amplified laser beam off the polarizers as an amplified laser output beam in exactly the same direction as the input laser beam.

  13. Spatial variability of the Arctic Ocean's double-diffusive staircase (United States)

    Shibley, N. C.; Timmermans, M.-L.; Carpenter, J. R.; Toole, J. M.


    The Arctic Ocean thermohaline stratification frequently exhibits a staircase structure overlying the Atlantic Water Layer that can be attributed to the diffusive form of double-diffusive convection. The staircase consists of multiple layers of O(1) m in thickness separated by sharp interfaces, across which temperature and salinity change abruptly. Through a detailed analysis of Ice-Tethered Profiler measurements from 2004 to 2013, the double-diffusive staircase structure is characterized across the entire Arctic Ocean. We demonstrate how the large-scale Arctic Ocean circulation influences the small-scale staircase properties. These staircase properties (layer thicknesses and temperature and salinity jumps across interfaces) are examined in relation to a bulk vertical density ratio spanning the staircase stratification. We show that the Lomonosov Ridge serves as an approximate boundary between regions of low density ratio (approximately 3-4) on the Eurasian side and higher density ratio (approximately 6-7) on the Canadian side. We find that the Eurasian Basin staircase is characterized by fewer, thinner layers than that in the Canadian Basin, although the margins of all basins are characterized by relatively thin layers and the absence of a well-defined staircase. A double-diffusive 4/3 flux law parametrization is used to estimate vertical heat fluxes in the Canadian Basin to be O(0.1) W m-2. It is shown that the 4/3 flux law may not be an appropriate representation of heat fluxes through the Eurasian Basin staircase. Here molecular heat fluxes are estimated to be between O(0.01) and O(0.1) W m-2. However, many uncertainties remain about the exact nature of these fluxes.


    National Research Council Canada - National Science Library



    Layered double hydroxides (LDHs) are class of materials with useful properties associated with their anion exchange abilities for a wide range of applications including bio and environmental problems...

  15. Colored Flag by Double Refraction. (United States)

    Reid, Bill


    Describes various demonstrations that illustrate double refraction and rotation of the plane of polarization in stressed, transparent plastics, with the consequent production of colored designs. (ZWH)

  16. Double-Skin Facade

    DEFF Research Database (Denmark)

    Kalyanova, Olena

    Double-Skin Facades (DSF) are gaining popularity that, in fact, appears to be independent from sturdy critics of the concept in the past years. DSF buildings are being built in Europe and worldwide, DSF concept is being taught at schools of architecture and fully glazed office buildings are being...... favored by companies and their employees. To bring the reduction of energy use in these buildings application of suitable tools and methods is necessary to achieve successful design solutions. Earlier work on the topic of DSF modelling was examined from various publications. As a result, the main...... difficulties experienced by scientists when attempting to model DSF thermal and energy performance were examined. In addition, the lack of experimental studies and empirical validation of models was realized, many numerical models have not been empirically validated and most of them require an expert knowledge...

  17. Layered double hydroxides

    DEFF Research Database (Denmark)

    López Rayo, Sandra; Imran, Ahmad; Hansen, Hans Chr. Bruun


    A novel zinc (Zn) fertilizer concept based on Zn doped layered double hydroxides (Zn-doped Mg-Fe-LDHs) has been investigated. Zn-doped Mg-Fe-LDHs were synthetized, their chemical composition was analyzed and their nutrient release was studied in buffered solutions with different pH values. Uptake...... of Zn by barley (Hordeum vulgare cv. Antonia) was evaluated in short- (8 weeks), medium- (11 weeks) and long-term (28 weeks) experiments in quartz sand and in a calcareous soil enriched with Zn-doped Mg-Fe-LDHs. The Zn release rate of the Zn-doped Mg-Fe-LDHs was described by a first-order kinetics...

  18. Dual double field theory

    Energy Technology Data Exchange (ETDEWEB)

    Bergshoeff, Eric A. [Centre for Theoretical Physics, University of Groningen,Nijenborgh 4, 9747 AG Groningen (Netherlands); Hohm, Olaf [Simons Center for Geometry and Physics, Stony Brook University,Stony Brook, NY 11794-3636 (United States); Penas, Victor A. [Centre for Theoretical Physics, University of Groningen,Nijenborgh 4, 9747 AG Groningen (Netherlands); Riccioni, Fabio [INFN - Sezione di Roma, Dipartimento di Fisica, Università di Roma “La Sapienza”,Piazzale Aldo Moro 2, 00185 Roma (Italy)


    We present the dual formulation of double field theory at the linearized level. This is a classically equivalent theory describing the duals of the dilaton, the Kalb-Ramond field and the graviton in a T-duality or O(D,D) covariant way. In agreement with previous proposals, the resulting theory encodes fields in mixed Young-tableau representations, combining them into an antisymmetric 4-tensor under O(D,D). In contrast to previous proposals, the theory also requires an antisymmetric 2-tensor and a singlet, which are not all pure gauge. The need for these additional fields is analogous to a similar phenomenon for “exotic' dualizations, and we clarify this by comparing with the dualizations of the component fields. We close with some speculative remarks on the significance of these observations for the full non-linear theory yet to be constructed.

  19. Coupled Double Quantum Wells

    Directory of Open Access Journals (Sweden)

    Élder Mantovani Lopes


    Full Text Available The progress of the semiconductor growth techniques allows the opportunity to produce new semiconductors devices that may contribute to the development of the nanotechnology. The fabrication of semiconductor heterostructures with high quality allows the obtaining of new effects based on the quantum properties of those systems, which have stimulated great technological interest, especially on the optoelectronic and telecommunications fields. In this work some basic concepts related to one of those heterostructures are discussed: the Coupled Double Quantum Well (CDQW. The deduction of the expression for the determination of the energy levels in CDQWs is presented in details. The results obtained through this expression are compared with experimental results obtained through photoluminescence (PL measurements, complementing the work.

  20. Draping Double-Layer Woven Fabrics Onto Double-Curvature ...

    African Journals Online (AJOL)

    Draping woven fabrics to complex parts with double curvature leads to complex redistribution and reorientation of the yarns in composites reinforced with woven preforms. To reduce the risk of fabric tearing or wrinkling we propose to use double-layer woven fabrics. This paper presents a simulation model for draping

  1. Orbits of four double stars

    Directory of Open Access Journals (Sweden)

    Novaković B.


    Full Text Available We present orbits of four double stars. Orbits of stars WDS 23516+4205 = ADS 17050 and WDS 18239+5848 = ADS 11336 were calculated for the first time. Orbits of double stars WDS 02022+3643 = ADS 1613 and WDS 18443+3940 = ADS 11635 were revised. We have also determined their masses, dynamical parallaxes and ephemerides.

  2. Empirically Unbinding the Double Bind. (United States)

    Olson, David H.

    The theoretical concept of the double bind and the possibilities for researching it are discussed. The author has observed that theory and research, which should be reciprocal and mutually beneficial, have been working, as concerns the double bind, at odds with one another. Two approaches to empirically investigating the concept are considered via…

  3. Hedging Double Barriers with Singles

    NARCIS (Netherlands)

    Sbuelz, A.


    Double barrier options provide risk managers with good-deal flexibility in tailoring portfolio returns.Their hedges offer full protection only if unwound along the barriers.This work provides non-dynamic hedges that project the risk of double barriers on to single barriers.Non-dynamic hedges

  4. Double layer relaxation in colloids

    NARCIS (Netherlands)

    Kijlstra, J.


    The purpose of the present study is to improve our insight into the relaxation of the electrical double layer around particles in hydrophobic sols. A detailed knowledge of the relaxation mechanisms is required to explain the behaviour of sols under conditions where the double layer is

  5. Double parton scattering theory overview

    NARCIS (Netherlands)

    Diehl, Markus; Gaunt, Jonathan R.


    The dynamics of double hard scattering in proton-proton collisions is quite involved compared with the familiar case of single hard scattering. In this contribution, we review our theoretical understanding of double hard scattering and of its interplay with other reaction mechanisms.

  6. Natural double inflation (United States)

    Occhionero, F.; Litterio, M.; Capozziello, S.; Amendola, L.

    The astronomical interest of double inflation stems from the possibility it gives of inserting a feature in an otherwise featureless (or scale invariant) perturbation spectrum, precisely at the scale (100 Mpc, say) that goes through the horizon at the (sharp) separations between the two successive inflations. Double inflation occurs when two scalar fields (or inflatons) dominate sequentially the cosmic expansion or when vacuum polarization — Ricci scalar R squared added to the Lagrangian — is taken into account and only one inflaton ψ is present. (This perhaps is more natural as it exploits quantum effects to reduce to one the number of the ad hoc ingredients.) In that case we know from Starobinsky's pioneering work that the first inflation is driven by R — rightly called then scalaron — under the rules of Fourth Order Gravity, (FOG), while the second is driven by ψ under the rules of ordinary General Relativity, (GR). Unfortunately most of the appeal of the scalaron-inflaton scenario in relation to the feature in the perturbation spectrum, is lost because a delicate fine tuning of the value of the (second) inflaton at the beginning of the second inflation is required, in the absence of which the two inflations merge in one and no scale is singled out. In order to overcome this difficulty, we introduce in the Lagrangian density a new scalar coupling between ψ and R2, analogous to the well known non minimal coupling between ψ and R of canonical GR. We show that in this way the two inflationary episodes of FOG and GR may be neatly distinguished from each other, regardless of the initial value of ψ. This is due to the influence of the coupling on the shape of the conformal potential, in which one can easily carve a channel of evolution, consisting in fact of two orthogonal valleys. Then, for most of phase space the attractor is this doubly inflationary trajectory that lies at the bottom of the two valleys (Fig. 1). In fact, in this case the Universe first

  7. A Handbook of Double Stars (United States)

    Crossley, Edward; Gledhill, Joseph; Wilson, James M.


    Preface; Part I. Historical, and Descriptive of Instruments and Methods: 1. Historical introduction; 2. The Equatorial: its construction and adjustments; 3. Some account of the Equatorials which have been used by double-star observers; 4. The micrometer; 5. Methods of observing double stars; Part II. On the Calculation of the Orbit of a Binary Star: 1. Introduction; 2. Example of an orbit worked by a graphical method; 3. Dr. Doberck's example of an orbit worked by analytical methods; 4. On relative rectilinear motion; 5. On the effect of proper motion and parallax on the observed position angles and distance of an optically double star; 6. On the errors of observation and the combination of observations; Part III. The Catalogue and Measures: Introductory remarks; A catalogue of binary and other double starts deserving of attention; Lists of measures, with historical notes, etc.; Supplementary list of measures; Appendix; Additional notes to measures; Binary stars classified; Note on systematic errors in the measures of angle and distance of double stars; Part IV. Bibliography: A. Some of the most important works and papers on double stars; B. Some papers on the micrometer; C. Some papers on the colours of double stars; Additional notes; Corrections 1880.

  8. Creative Double Bind in Oral Interpretation. (United States)

    Peterson, Eric E.; Langellier, Kristin M.


    Explains how oral interpretation is uniquely communicative and how the double bind theory of communication can include creativity. Discusses (1) double bind and oral interpretation, (2) creating aesthetic text, and (3) the performance of double bind. (PD)

  9. Hitchcock’s queer doubles

    Directory of Open Access Journals (Sweden)

    Alessandra Brandão


    Full Text Available   The “double” is a well-known Hitchcockian motif. Widelyreviewed under a psychoanalytical perspective, the issue ofthe double still presents other important challenges and thisarticle aims at discussing the queer doubles in Hitchcock’s films as “falsifiers” who are opposed to non-queer doubles thatemphasise narrative coherence and legibility. In films such asRebeca, Rope, Vertigo, The Birds, Psycho, and Frenzy, a doublecondenses impulses that are well described by Lee Edelman: “theviolent undoing of meaning, the loss of identity and coherence,the unnatural access to jouissance” (132. These doubles releasethe powers of the false as they complicate the return to an “order”.Therefore, we could argue that such characters are closer tobeing Deleuzian simulacra than psychoanalytical doppelgängers.

  10. Species doubling and effective Lagrangians

    Energy Technology Data Exchange (ETDEWEB)

    Creutz, M.; Tytgat, M.


    Coupling gauge fields to the chiral currents from an effective Lagrangian for pseudoscalar mesons naturally gives rise to a species doubling phenomenon similar to that seen with fermionic fields in lattice gauge theory. 17 refs.

  11. The Double Love Commandment

    Directory of Open Access Journals (Sweden)

    Francois P. Viljoen


    Full Text Available The Gospel of Matthew was written during a period of dispute between the Matthean community and their fellow Jews, with the Pharisees playing a leading role. The Matthean community was heir to the same scriptures as its opponents. They continued to have a firm commitment to the Torah, but they developed a distinctive understanding of it based on Jesus’ teaching. The formation of this community is investigated in this article, considering the Mediterranean perspectives of group-oriented societies prevalent in the first century. Such a group provided a sense of self and an interactive support system, where love functioned to bind the group together. The subordinates showed their undivided loyalty towards their superiors because of the favours they received from them, whilst they supported and cared for other members within the group as they care for themselves. Reading the double love commandment of Matthew 22:34−40 from this perspective reveals significant aspects of the community’s identity with regard to their commitment to God and their view of their neighbours. Die Dubbele Liefdesgebod. Die Matteusevangelie is gedurende ’n periode van konfliktussen die Matteusgemeenskap en mede-Jode geskryf met die Fariseërs in ’n leidende rol. Die Matteusgemeenskap het van dieselfde geskrifte as hulle opponente gebruik gemaak. Hulle was steeds aan die Torah lojaal, maar het ’n unieke interpretasie daarvan gehuldig, gebaseer op die onderrig van Jesus. In hierdie artikel word die vorming van die Matteusgemeenskap ondersoek met inagneming van die Mediterreense beskouing van die groepgeoriënteerde gemeenskappe wat tipies van die eerste eeu was. So ’n groep het aan individue ’n bewustheid van eie waarde verskaf te midde van ’n interaktiewe ondersteuningsisteem waarin liefde as samebindende faktor gefunksioneer het. Ondergeskiktes het onverdeelde lojaliteit teenoor hulle meerderes betoon vanweë die gunste wat hulle van die meerderes geniet het

  12. The Double Love Commandment

    Directory of Open Access Journals (Sweden)

    Francois P. Viljoen


    Full Text Available The Gospel of Matthew was written during a period of dispute between the Matthean community and their fellow Jews, with the Pharisees playing a leading role. The Matthean community was heir to the same scriptures as its opponents. They continued to have a firm commitment to the Torah, but they developed a distinctive understanding of it based on Jesus’ teaching. The formation of this community is investigated in this article, considering the Mediterranean perspectives of group-oriented societies prevalent in the first century. Such a group provided a sense of self and an interactive support system, where love functioned to bind the group together. The subordinates showed their undivided loyalty towards their superiors because of the favours they received from them, whilst they supported and cared for other members within the group as they care for themselves. Reading the double love commandment of Matthew 22:34−40 from this perspective reveals significant aspects of the community’s identity with regard to their commitment to God and their view of their neighbours.Die Dubbele Liefdesgebod. Die Matteusevangelie is gedurende ’n periode van konfliktussen die Matteusgemeenskap en mede-Jode geskryf met die Fariseërs in ’n leidende rol. Die Matteusgemeenskap het van dieselfde geskrifte as hulle opponente gebruik gemaak. Hulle was steeds aan die Torah lojaal, maar het ’n unieke interpretasie daarvan gehuldig, gebaseer op die onderrig van Jesus. In hierdie artikel word die vorming van die Matteusgemeenskap ondersoek met inagneming van die Mediterreense beskouing van die groepgeoriënteerde gemeenskappe wat tipies van die eerste eeu was. So ’n groep het aan individue ’n bewustheid van eie waarde verskaf te midde van ’n interaktiewe ondersteuningsisteem waarin liefde as samebindende faktor gefunksioneer het. Ondergeskiktes het onverdeelde lojaliteit teenoor hulle meerderes betoon vanweë die gunste wat hulle van die meerderes geniet het

  13. Keepers of the Double Stars


    Tenn, Joseph S.


    Astronomers have long tracked double stars in efforts to find those that are gravitationally-bound binaries and then to determine their orbits. Early catalogues by the Herschels, Struves, and others began with their own discoveries. In 1906 court reporter and amateur astronomer Sherburne Wesley Burnham published a massive double star catalogue containing data from many observers on more than 13,000 systems. Lick Observatory astronomer Robert Grant Aitken produced a much larger catalogue in 19...

  14. Double parton scattering in CMS

    CERN Document Server

    Sunar Cerci, Deniz


    Recent results on the double parton scattering measurements performed using the proton-proton collision data collected with the CMS detector are presented. The observables, which are sensitive to double parton scattering, are investigated after being corrected for detector effects and selection efficiencies. Multivariate analysis techniques are used for increasing the sensitivity. The effective cross section, $\\sigma_{eff}$ is also extracted using different processes at various center-of-mass energies.

  15. Supermagic Generalized Double Graphs 1

    Directory of Open Access Journals (Sweden)

    Ivančo Jaroslav


    Full Text Available A graph G is called supermagic if it admits a labelling of the edges by pairwise di erent consecutive integers such that the sum of the labels of the edges incident with a vertex is independent of the particular vertex. In this paper we will introduce some constructions of supermagic labellings of some graphs generalizing double graphs. Inter alia we show that the double graphs of regular Hamiltonian graphs and some circulant graphs are supermagic.

  16. A Transesterification Double Step Process - TDSP for biodiesel preparation from fatty acids triglycerides

    Energy Technology Data Exchange (ETDEWEB)

    Samios, D.; Pedrotti, F.; Nicolau, A.; Reiznautt, Q.B.; Martini, D.D.; Dalcin, F.M. [Laboratory of Instrumentation and Molecular Dynamic, Institute of Chemistry, Federal University of Rio Grande do Sul 9500, Bento Goncalves Av., Box 15003, Porto Alegre, RS (Brazil)


    This study introduces a two consecutive steps basic-acid transesterification process, (denominated Transesterification Double Step Process - TDSP) for biodiesel production from vegetable oils. The process involves homogeneous consecutive basic-acid catalysis steps and is characterized by formation of well-defined phases, easy separation procedures, high reaction velocity and high conversion efficiency. The proposed TDSP is different in relation to other traditional two-step procedures which normally include acid esterification followed by basic transesterification, or enzymatic or even supercritical transesterification conditions. The biodiesel (fatty acid methyl esters) was analyzed by standard biodiesel techniques in addition to {sup 1}H-NMR, indicating high quality and purity biodiesel products. The transesterification of sunflower and linseed oils resulted in oil conversions higher than 97% corresponding to yields of 85%. A probable reaction mechanism responsible for the process is presented. (author)

  17. Removal of lead from aqueous solution on glutamate intercalated layered double hydroxide

    Directory of Open Access Journals (Sweden)

    Shen Yanming


    Full Text Available Glutamate intercalated Mg–Al layered double hydroxide (LDH was prepared by co-precipitation and the removal of Pb2+ in the aqueous solution was investigated. The prepared samples were characterized by XRD, FT-IR and SEM. It was shown that glutamate can intercalate into the interlayer space of Mg–Al LDH. The glutamate intercalated Mg–Al LDH can effectively adsorb Pb2+ in the aqueous solution with an adsorption capacity of 68.49 mg g−1. The adsorption of Pb2+ on glutamate intercalated Mg–Al LDH fitted the pseudo-second-order kinetics model and the isotherm can be well defined by Langmuir model.

  18. Double-polarization observable G in neutral-pion photoproduction off the proton

    Energy Technology Data Exchange (ETDEWEB)

    Thiel, A.; Lang, M.; Afzal, F.; Beck, R.; Boese, S.; Funke, C.; Gottschall, M.; Gruener, M.; Hammann, C.; Hannappel, J.; Hartmann, J.; Hoffmeister, P.; Honisch, C.; Kaiser, D.; Kalinowsky, H.; Kalischewski, F.; Klassen, P.; Klempt, E.; Koop, K.; Kube, M.; Mahlberg, P.; Mueller, J.; Muellers, J.; Piontek, D.; Schmidt, C.; Seifen, T.; Sokhoyan, V.; Spieker, K.; Thoma, U.; Urban, M.; Pee, H. van; Walther, D.; Wendel, C.; Winnebeck, A. [Universitaet Bonn, Helmholtz-Institut fuer Strahlen- und Kernphysik, Bonn (Germany); Eberhardt, H.; Bantes, B.; Dutz, H.; Elsner, D.; Ewald, R.; Fornet-Ponse, K.; Frommberger, F.; Goertz, S.; Hammann, D.; Hillert, W.; Jude, T.; Kammer, S.; Kleber, V.; Klein, F.; Reeve, S.; Runkel, S.; Schmieden, H. [Universitaet Bonn, Physikalisches Institut, Bonn (Germany); Anisovich, A.V.; Bayadilov, D.; Nikonov, V.; Sarantsev, A. [Universitaet Bonn, Helmholtz-Institut fuer Strahlen- und Kernphysik, Bonn (Germany); Petersburg Nuclear Physics Institute, Gatchina (Russian Federation); Bichow, M.; Meyer, W.; Reicherz, G. [Ruhr-Universitaet Bochum, Institut fuer Experimentalphysik I, Bochum (Germany); Brinkmann, K.T.; Gutz, E. [Universitaet Bonn, Helmholtz-Institut fuer Strahlen und Kernphysik, Bonn (Germany); Universitaet Giessen, II. Physikalisches Institut, Giessen (Germany); Crede, V. [Florida State University, Department of Physics, Tallahassee, FL (United States); Dieterle, M.; Keshelashvili, I.; Krusche, B.; Witthauer, L. [Universitaet Basel, Institut fuer Physik, Basel (Switzerland); Friedrich, S.; Makonyi, K.; Metag, V.; Nanova, M. [Universitaet Giessen, II. Physikalisches Institut, Giessen (Germany); Gridnev, A.; Lopatin, I. [Petersburg Nuclear Physics Institute, Gatchina (Russian Federation); Wilson, A. [Universitaet Bonn, Helmholtz-Institut fuer Strahlen- und Kernphysik, Bonn (Germany); Florida State University, Department of Physics, Tallahassee, FL (United States); Collaboration: The CBELSA/TAPS Collaboration


    This paper reports on a measurement of the double-polarization observable G in π{sup 0} photoproduction off the proton using the CBELSA/TAPS experiment at the ELSA accelerator in Bonn. The observable G is determined from reactions of linearly polarized photons with longitudinally polarized protons. The polarized photons are produced by bremsstrahlung off a diamond radiator of well-defined orientation. A frozen spin butanol target provides the polarized protons. The data cover the photon energy range from 617 to 1325 MeV and a wide angular range. The experimental results for G are compared to predictions by the Bonn-Gatchina (BnGa), Juelich-Bonn (JueBo), MAID and SAID partial wave analyses. Implications of the new data for the pion photoproduction multipoles are discussed. (orig.)

  19. Alternate Double Single Track Lines

    Energy Technology Data Exchange (ETDEWEB)

    Moraga Contreras, P.; Grande Andrade, Z.; Castillo Ron, E.


    The paper discusses the advantages and shortcomings of alternate double single track (ADST) lines with respect to double track lines for high speed lines. ADST lines consists of sequences of double and single track segments optimally selected in order to reduce the construction and maintenance costs of railway lines and to optimize the timetables used to satisfy a given demand. The single tracks are selected to coincide with expensive segments (tunnels and viaducts) and the double tracks are chosen to coincide with flat areas and only where they are necessary. At the same time, departure times are adjusted for trains to cross at the cheap double track segments. This alternative can be used for new lines and also for existing conventional lines where some new tracks are to be constructed to reduce travel time (increase speed). The ADST proposal is illustrated with some examples of both types (new lines and where conventional lines exist), including the Palencia-Santander, the Santiago-Valparaíso-Viña del Mar and the Dublin-Belfast lines, where very important reductions (90 %) are obtained, especially where a railway infrastructure already exist. (Author)

  20. Azeglio Bemporad and the "BEM" Double Stars (United States)

    Smith, Steven; Prunotto, Marco


    This paper aims to describe the scientific context and the life of early 20th century Italian astronomer Azeglio Bemporad (1875-1945), his work on double stars, and how the “BEM” doubles were incorporated into the Washington Double Star catalog. Included are new measures, a complete photo gallery of all 61 of his double star systems, and copies of his double star publications.

  1. The Doubling Undone? Double Effect in Recent Medical Ethics ...

    African Journals Online (AJOL)

    This article treats recent bioethical discussions of double effect reasoning (DER), offering a summary account of DER and construing it as rooted in a sensible view of what is central to someone's identity as a moral agent. It then treats objections raised in recent years by Judith Thomson, Alison McIntyre, and Frances Kamm ...

  2. Doubled-ended ceramic thyratron

    CERN Multimedia


    The double-ended ceramic thyratron CX 1171 B, with its coaxial voltage divider for the SPS. Such a switch, paralleled by three ignitrons in series forms the "thyragnitron" arrangement, and can switch 10 kA, 25 ms pulses, with very fast rise times.

  3. Magnetoresistance stories of double perovskites

    Indian Academy of Sciences (India)

    out. Keywords. Tunnelling magnetoresistance; tunnel boundary; disorder; double perovskite. PACS Nos 75.47.−m; 73.40.Gk; 72.80.Ga. 1. Introduction. Magnetoresistance (MR) is the property of a material to change the value of its electri- cal resistance when an external magnetic field is applied. This phenomenon was first.

  4. Double Coffee opens in China

    Index Scriptorium Estoniae


    Läti suursaadik Ingrida Levrence avas esimese Double Coffee kohviku Hiina pealinnas Pekingi südames. Rahvusvaheline kohvikukett kavatseb laieneda mõne kohviku võrra igal aastal. Seni tegutsetakse Lätis, Eestis, Leedus, Ukrainas ja Valgevenes

  5. Micrometer measurements of double stars

    Directory of Open Access Journals (Sweden)

    Zulević D.J.


    Full Text Available A set of 71 measurements of double and multiple stars, carried out with the Large Zeiss Refractor 65/1055 cm of the Belgrade Observatory, is communicated. The bulk of these measurements, 41 in all, unpublished yet, is due to late D. Zulević.

  6. A Double-Minded Fractal (United States)

    Simoson, Andrew J.


    This article presents a fun activity of generating a double-minded fractal image for a linear algebra class once the idea of rotation and scaling matrices are introduced. In particular the fractal flip-flops between two words, depending on the level at which the image is viewed. (Contains 5 figures.)

  7. Formation of Double-Shelled Zinc-Cobalt Sulfide Dodecahedral Cages from Bimetallic Zeolitic Imidazolate Frameworks for Hybrid Supercapacitors. (United States)

    Zhang, Peng; Guan, Bu Yuan; Yu, Le; Lou, Xiong Wen David


    Complex metal-organic frameworks used as precursors allow design and construction of various nanostructured functional materials which might not be accessible by other methods. Here, we develop a sequential chemical etching and sulfurization strategy to prepare well-defined double-shelled zinc-cobalt sulfide (Zn-Co-S) rhombic dodecahedral cages (RDCs). Yolk-shelled zinc/cobalt-based zeolitic imidazolate framework (Zn/Co-ZIF) RDCs are first synthesized by a controlled chemical etching process, followed by a hydrothermal sulfurization reaction to prepare double-shelled Zn-Co-S RDCs. Moreover, the strategy reported in this work enables easy control of the Zn/Co molar ratio in the obtained double-shelled Zn-Co-S RDCs. Owing to the structural and compositional benefits, the obtained double-shelled Zn-Co-S RDCs exhibit enhanced performance with high specific capacitance (1266 F g-1 at 1 A g-1 ), good rate capability and long-term cycling stability (91 % retention over 10,000 cycles) as a battery-type electrode material for hybrid supercapacitors. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Pathways to doubled haploidy: chromosome doubling during androgenesis. (United States)

    Seguí-Simarro, J M; Nuez, F


    Production of doubled haploid (DH) plants through androgenesis induction is a promising and convenient alternative to conventional selfing techniques for the generation of pure lines for breeding programs. This process comprises two main steps: induction of androgenesis and duplication of the haploid genome. Such duplication is sometimes indirectly induced by the treatments used to promote androgenic development. But usually, an additional step of direct chromosome doubling must be included in the protocol. Duplication of the haploid genome of androgenic individuals has been thought to occur through three mechanisms: endoreduplication, nuclear fusion and c-mitosis. In this review we will revise and analyze the evidences supporting each of the proposed mechanisms and their relevance during androgenesis induction, embryo/callus development and plant regeneration. Special attention will be devoted to nuclear fusion, whose evidences are accumulating in the last years. 2008 S. Karger AG, Basel

  9. Lightweight Double Neutron Star Found (United States)

    Kohler, Susanna


    More than forty years after the first discovery of a double neutron star, we still havent found many others but a new survey is working to change that.The Hunt for PairsThe observed shift in the Hulse-Taylor binarys orbital period over time as it loses energy to gravitational-wave emission. [Weisberg Taylor, 2004]In 1974, Russell Hulse and Joseph Taylor discovered the first double neutron star: two compact objects locked in a close orbit about each other. Hulse and Taylors measurements of this binarys decaying orbit over subsequent years led to a Nobel prize and the first clear evidence of gravitational waves carrying energy and angular momentum away from massive binaries.Forty years later, we have since confirmed the existence of gravitational waves directly with the Laser Interferometer Gravitational-Wave Observatory (LIGO). Nonetheless, finding and studying pre-merger neutron-star binaries remains a top priority. Observing such systems before they merge reveals crucial information about late-stage stellar evolution, binary interactions, and the types of gravitational-wave signals we expect to find with current and future observatories.Since the Hulse-Taylor binary, weve found a total of 16 additional double neutron-star systems which represents only a tiny fraction of the more than 2,600 pulsars currently known. Recently, however, a large number of pulsar surveys are turning their eyes toward the sky, with a focus on finding more double neutron stars and at least one of them has had success.The pulse profile for PSR J1411+2551 at 327 MHz. [Martinez et al. 2017]A Low-Mass DoubleConducted with the 1,000-foot Arecibo radio telescope in Puerto Rico, the Arecibo 327 MHz Drift Pulsar Survey has enabled the recent discovery of dozens of pulsars and transients. Among them, as reported by Jose Martinez (Max Planck Institute for Radio Astronomy) and coauthors in a recent publication, is PSR J1411+2551: a new double neutron star with one of the lowest masses ever measured

  10. Outcome of the Double-J Stent Placement in Pediatric Kidney Transplant: A Single Center Experience. (United States)

    Sözen, Hakan; Özen, Onur; Fidan, Kibriya; Söylemezoğlu, Oğuz; Dalgıç, Aydın


    Double J stent placement at kidney transplant may reduce stenosis or leakage complication rates. However, placement may also increase risk for early urinary tract infection (ie, placement is not well defined. We analyzed retrospective data from children who received transplants at the Gazi University Transplantation Center and Pediatric Nephrology (Ankara, Turkey) for outcomes related to double J stents. At our center, double J stent placement decision is made by the transplant surgery team during operation. Placements were routinely performed in all transplant recipients. Stent removal occurs within 6 week after transplant. Among 42 transplants since 2006, early urinary tract infection was seen in 7% and stenosis in 3.6% of patients, with no leakage reported. Mean stent removal time was 6 ± 0.5 weeks. Early urinary tract infection was seen in 3 recipients with posterior urethral valve and neurogenic bladder (2 recipients) and meningoma cells and neurogenic bladder (1 recipient). All 3 recipients with early urinary tract infection received clean intermittent catheterization after transplant for adequate emptying of the bladder. In our study group, stent complications such as migration (2 patients) and hematuria (1 patient) were seen, but crusting, breakage, and stone formation were not seen. The 3 patients with urinary tract infection had neurogenic bladder types, complicating the urine outflow system. Stent placement was not a significant risk factor for early urinary tract infection and but had a protective effect. In our study group, we observed no risk factors for routine double J stent placement in pediatric renal transplant procedures. Stent placement was not a risk factor for early urinary tract infection. However, regardless of stent placement, when a recipient had complicated urologic outflow problems, infection became a long-term hurdle.

  11. Hydrated-ion ordering in electrical double layers. (United States)

    Espinosa-Marzal, Rosa M; Drobek, Tanja; Balmer, Tobias; Heuberger, Manfred P


    In this work we revisit the surface forces measured between two atomically flat mica surfaces submerged in a reservoir of potassium nitrate (KNO(3)) solution. We consider a comprehensive range of concentrations from 0.08 mM to 2.6 M. The significantly improved resolution available from the extended surface force apparatus (eSFA) allows the distinction of hydration structures and hydrated-ion correlations. Above concentrations of 0.3 mM, hydrated-ion correlations give rise to multiple collective transitions (4 ± 1 Å) in the electrical double layers upon interpenetration. These features are interpreted as the result of hydrated-ion ordering (e.g. layering), in contrast to the traditional interpretation invoking water layering. The hydrated-ion layer adjacent to the surface (i.e. outer Helmholtz layer) is particularly well defined and plays a distinctive role. It can be either collectively expelled in a 5.8 ± 0.3 Å film-thickness transition or collectively forced to associate with the surface by external mechanical work. The latter is observed as a characteristic 2.9 ± 0.3 Å film-thickness transition along with an abrupt decrease of surface adhesion at concentrations above 1 mM. At concentrations as low as 20 mM, attractive surface forces are measured in deviation to the DLVO theory. The hydration number in the confined electrolyte seems to be significantly below that of the bulk. A 1-3 nm thick ionic layer solidifies at the surfaces at concentrations >100 mM, i.e. below bulk saturation.

  12. TOPICAL REVIEW: Double beta decay (United States)

    Faessler, Amand; Simkovic, Fedor


    We review the recent developments in the field of nuclear double beta decay, which is presently an important topic in both nuclear and particle physics. The mechanism of lepton number violation within the neutrinoless double beta decay (0954-3899/24/12/001/img5-decay) is discussed in the context of the problem of neutrino mixing and the R-parity violating supersymmetric extensions of the standard model. The problem of reliable determination of the nuclear matrix elements governing both two-neutrino and neutrinoless modes of the double beta decay is addressed. The validity of different approximation schemes in the considered nuclear structure studies is analysed and the role of the Pauli exclusion principle for a correct treatment of nuclear matrix elements is emphasized. The constraints on different lepton-number violating parameters such as effective electron neutrino mass, effective right-handed weak interaction parameters, effective Majoron coupling constant and R-parity violating SUSY parameters are derived from the best presently available experimental limits on the half-life of 0954-3899/24/12/001/img5-decay.

  13. Double-Critical Graphs and Complete Minors

    DEFF Research Database (Denmark)

    Kawarabayashi, Ken-ichi; Pedersen, Anders Sune; Toft, Bjarne


      A connected $k$-chromatic graph $G$ is double-critical if for all edges $uv$ of $G$ the graph $G - u - v$ is $(k-2)$-colourable. The only known double-critical $k$-chromatic graph is the complete $k$-graph $K_k$. The conjecture that there are no other double-critical graphs is a special case of...

  14. Double Modals as Single Lexical Items. (United States)

    Di Paolo, Marianna


    Study of East and West Texans' (N=62) use of double modals as single lexical items and their syntactic and semantic characteristics found that neither Aux nor subcategorization analysis could account for both single-modal and double-modal dialects. Double modals, however, could conceivably be analyzed as two-word lexical items such as idioms or…

  15. Double pot and double compartment: integrating two approaches to study nutrient uptake by arbuscular mycorrhizal fungi

    NARCIS (Netherlands)

    Cardoso, I.M.; Boddington, C.L.; Janssen, B.H.; Oenema, O.; Kuyper, T.W.


    The double compartment technique has been commonly used in studies on nutrient uptake by mycorrhizas whereas the double pot technique has been used to assess the nutritional stress of plants grown in different soils. A combination of the double pot and the double compartment technique was used as a

  16. Synthesis and Characterization of Well-Defined Soluble Alq3- and Znq2-Functionalized Polymers via RAFT Copolymerization

    Directory of Open Access Journals (Sweden)

    Chengchao Wang


    Full Text Available The reversible addition-fragmentation chain transfer (RAFT copolymerizations of 2-((8-hydroxyquinolin-5-ylmethoxyethyl methacrylate (HQHEMA with styrene (St or methyl methacrylate (MMA were successfully carried out in the presence of 2-cyanoprop-2-yl dithionaphthalenoate (CPDN. The polymerization behaviors showed the typical living natures by the first-order polymerization kinetics, the linear dependence of molecular weights of the polymers on the monomer conversions with the relatively narrow molecular weight distributions (Mw/Mn, and the successful chain extension experiments. The soluble polymers having tris(8-hydroxyquinolinealuminum (Alq3 and bis(8-hydroxyquinoline znic(II (Znq2 side chains were obtained via complexation of the polymers with aluminium isopropoxide or zinc acetate in the presence of monomeric 8-hydroxyquinoline, which had strong fluorescent emission at 520 nm. The obtained polymers were characterized by GPC, NMR, UV-vis, and fluorescent spectra.


    Energy Technology Data Exchange (ETDEWEB)

    Lenardic, A. [Department of Earth Science, Rice University, MS 126, P.O. Box 1892, Houston, TX 77251-1892 (United States); Crowley, J. W., E-mail:, E-mail: [Department of Earth and Planetary Science, Harvard University, 20 Oxford St., Cambridge, MA 02138 (United States)


    A model of coupled mantle convection and planetary tectonics is used to demonstrate that history dependence can outweigh the effects of a planet's energy content and material parameters in determining its tectonic state. The mantle convection-surface tectonics system allows multiple tectonic modes to exist for equivalent planetary parameter values. The tectonic mode of the system is then determined by its specific geologic and climatic history. This implies that models of tectonics and mantle convection will not be able to uniquely determine the tectonic mode of a terrestrial planet without the addition of historical data. Historical data exists, to variable degrees, for all four terrestrial planets within our solar system. For the Earth, the planet with the largest amount of observational data, debate does still remain regarding the geologic and climatic history of Earth's deep past but constraints are available. For planets in other solar systems, no such constraints exist at present. The existence of multiple tectonic modes, for equivalent parameter values, points to a reason why different groups have reached different conclusions regarding the tectonic state of extrasolar terrestrial planets larger than Earth ({sup s}uper-Earths{sup )}. The region of multiple stable solutions is predicted to widen in parameter space for more energetic mantle convection (as would be expected for larger planets). This means that different groups can find different solutions, all potentially viable and stable, using identical models and identical system parameter values. At a more practical level, the results argue that the question of whether extrasolar terrestrial planets will have plate tectonics is unanswerable and will remain so until the temporal evolution of extrasolar planets can be constrained.

  18. Current rectification in a single GaN nanowire with a well-defined p-n junction (United States)

    Cheng, Guosheng; Kolmakov, Andrei; Zhang, Youxiang; Moskovits, Martin; Munden, Ryan; Reed, Mark A.; Wang, Guangming; Moses, Daniel; Zhang, Jinping


    This letter discusses Mg incorporation in GaN nanowires with diameters ˜35 nm, fabricated by vapor-liquid-solid synthesis in p-type nanowires. Turning on the Mg doping halfway through the synthesis produced nanowires with p-n junctions that showed excellent rectification properties down to 2.6 K. The nanowires are shown to possess good-quality, crystalline, hexagonal GaN inner cores surrounded by an amorphous GaN outer layer. Most wires grow such that the crystalline c axis is normal to the long axis of the nanowire. The temperature dependence of the current-voltage characteristics is consistent with electron tunneling through a voltage-dependent barrier.

  19. Surface Structure Dependence of SO 2 Interaction with Ceria Nanocrystals with Well-Defined Surface Facets

    Energy Technology Data Exchange (ETDEWEB)

    Tumuluri, Uma; Li, Meijun; Cook, Brandon G.; Sumpter, Bobby; Dai, Sheng; Wu, Zili


    The effects of the surface structure of ceria (CeO2) on the nature, strength, and amount of species resulting from SO2 adsorption were studied using in situ IR and Raman spectroscopies coupled with mass spectrometry, along with first-principles calculations based on density functional theory (DFT). CeO2 nanocrystals with different morphologies, namely, rods (representing a defective structure), cubes (100 facet), and octahedra (111 facet), were used to represent different CeO2 surface structures. IR and Raman spectroscopic studies showed that the structure and binding strength of adsorbed species from SO2 depend on the shape of the CeO2 nanocrystals. SO2 adsorbs mainly as surface sulfites and sulfates at room temperature on CeO2 rods, cubes, and octahedra that were either oxidatively or reductively pretreated. The formation of sulfites is more evident on CeO2 octahedra, whereas surface sulfates are more prominent on CeO2 rods and cubes. This is explained by the increasing reducibility of the surface oxygen in the order octahedra < cubes < rods. Bulk sulfites are also formed during SO2 adsorption on reduced CeO2 rods. The formation of surface sulfites and sulfates on CeO2 cubes is in good agreement with our DFT results of SO2 interactions with the CeO2(100) surface. CeO2 rods desorb SO2 at higher temperatures than cubes and octahedra nanocrystals, but bulk sulfates are formed on CeO2 rods and cubes after high-temperature desorption whereas only some surface sulfates/sulfites are left on octahedra. This difference is rationalized by the fact that CeO2 rods have the highest surface basicity and largest amount of defects among the three nanocrystals, so they bind and react with SO2 strongly and are the most degraded after SO2 adsorption cycles. The fundamental understanding obtained in this work on the effects of the surface structure and defects on the interaction of SO2 with CeO2 provides insights for the design of more sulfur-resistant CeO2-based catalysts.

  20. Predicting Alzheimer's disease by classifying 3D-Brain MRI images using SVM and other well-defined classifiers (United States)

    Matoug, S.; Abdel-Dayem, A.; Passi, K.; Gross, W.; Alqarni, M.


    Alzheimer's disease (AD) is the most common form of dementia affecting seniors age 65 and over. When AD is suspected, the diagnosis is usually confirmed with behavioural assessments and cognitive tests, often followed by a brain scan. Advanced medical imaging and pattern recognition techniques are good tools to create a learning database in the first step and to predict the class label of incoming data in order to assess the development of the disease, i.e., the conversion from prodromal stages (mild cognitive impairment) to Alzheimer's disease, which is the most critical brain disease for the senior population. Advanced medical imaging such as the volumetric MRI can detect changes in the size of brain regions due to the loss of the brain tissues. Measuring regions that atrophy during the progress of Alzheimer's disease can help neurologists in detecting and staging the disease. In the present investigation, we present a pseudo-automatic scheme that reads volumetric MRI, extracts the middle slices of the brain region, performs segmentation in order to detect the region of brain's ventricle, generates a feature vector that characterizes this region, creates an SQL database that contains the generated data, and finally classifies the images based on the extracted features. For our results, we have used the MRI data sets from the Alzheimer's Disease Neuroimaging Initiative (ADNI) database.

  1. Molecular characterization of apocrine carcinoma of the breast: validation of an apocrine protein signature in a well-defined cohort

    DEFF Research Database (Denmark)

    Celis, J.E.; Cabezon, T.; Moreira, José


    Invasive apocrine carcinomas (IACs), as defined by morphological features, correspond to 0.3-4% of all invasive ductal carcinomas (IDC), and despite the fact that they are histologically distinct from other breast lesions there are currently no standard molecular criteria available for their diag......Invasive apocrine carcinomas (IACs), as defined by morphological features, correspond to 0.3-4% of all invasive ductal carcinomas (IDC), and despite the fact that they are histologically distinct from other breast lesions there are currently no standard molecular criteria available...

  2. Postantibiotic effect of colistin alone and combined with vancomycin or meropenem against Acinetobacter spp. with well defined resistance mechanisms. (United States)

    Bedenić, Branka; Beader, Natasa; Godič-Torkar, Karmen; Prahin, Esmina; Mihaljević, Ljiljana; Ćačić, Marko; Vraneš, Jasmina


    Previous studies found short postantibiotic effect of colistin on Acinetobacter baumannii. Many studies have evaluated the potential for synergy between colistin and other antibiotics against A. baumannii. The aim of this study was to determine in vitro synergy and postantibiotic effect (PAE) of colistin alone and combined with other antibiotics (vancomycin or meropenem) against eight carbapenem-non-susceptible Acinetobacter spp. strains with defined resistance mechanisms. It was hypothesised that vancomycin or meropenem would prologue the PAE of colistin since it was previously found that they exert synergism with colistin in time-kill kinetics and chequerboard analysis. After exposure of 1 hour colistin alone exhibited the negative ( - 0.07 hour) (OXA-143), short (0.2-1.82 hours) (OXA-24, OXA-58, OXA-72, VIM-1+OXA-23, OXA-58+NDM-1, ISAba1/OXA-69) or moderate PAE (3.2 hours) for OXA-23 positive strain. When combined with vancomycin, the PAE was moderate (1.7-4 hours) with OXA-23, OXA-23+VIM-1, OXA-72 and OXA-24 positive strains while with OXA-58, OXA-143, OXA-58/NDM-1 and ISAba1/OXA-69 positive strains, it was not possible to calculate mean duration of PAE because there was no regrowth after exposure to antibiotics or it was longer than 5 hours. The combination with meropenem resulted in short (0.2 hours) (OXA-143), moderate (2.4-3.73 hours) (OXA-24, OXA-58, OXA-23, OXA-23+VIM-1), long PAE of 5 hours (OXA-23) or longer than 5 hours (OXA-58+VIM-1, ISAba1/OXA-69). From the clinical point of view, the prolongation of colistin PAE when combined with other antibiotics could provide a rationale for the modification of the dosing interval and could be important for the optimization of the treatment regimen and the minimization of drug-induced side effects.

  3. Customized high resolution CGH-array for clinical diagnosis reveals additional genomic imbalances in previous well-defined pathological samples. (United States)

    Vallespín, Elena; Palomares Bralo, María; Mori, M Ángeles; Martín, Rubén; García-Miñaúr, Sixto; Fernández, Luis; de Torres, M Luisa; García-Santiago, Fe; Mansilla, Elena; Santos, Fernando; M-Montaño, Victoria E; Crespo, M Carmen; Martín, Sol; Martínez-Glez, Victor; Delicado, Alicia; Lapunzina, Pablo; Nevado, Julián


    High-resolution array comparative genomic hybridization (aCGH) is a powerful molecular cytogenetic tool that is being adopted for diagnostic evaluation of genomic imbalances and study disease mechanisms and pathogenesis. We report on the design and use, of a custom whole-genome oligonucleotide-based array (called KaryoArray®v3.0; Agilent-based 8 × 60 K) for diagnostic setting, which was able to detect new and unexpected rearrangements in 11/63 (~17.5%) of previous known pathological cases associated with known genetic disorders, and in the second step it identified at least one causal genomic imbalance responsible of the phenotype in ~20% of patients with psychomotor development delay and/or intellectual disability. To validate the array, first; we blindly tested 120 samples; 63 genomic imbalances that had previously been detected by karyotyping, FISH and/or MLPA, and 57 sex-matched control samples from healthy individuals; secondly a prospective study of 540 patients with intellectual disabilities, autism spectrum disorder and multiple congenital anomalies were evaluated to confirm the utility of the tool. These data indicate that implementation of array technologies as the first-tier test may reveal that additional genomic imbalances could co-exist in patients with trisomies and classical del/dup syndromes, suggesting that aCGH may also be indicated in these individuals, at least when phenotype does not match completely with genotype. Copyright © 2013 Wiley Periodicals, Inc.

  4. Well-defined star-shaped conjugated macroelectrolytes as efficient electron-collecting interlayer for inverted polymer solar cells. (United States)

    Xu, Weidong; Kan, Zhipeng; Ye, Tengling; Zhao, Li; Lai, Wen-Yong; Xia, Ruidong; Lanzani, Guglielmo; Keivanidis, Panagiotis E; Huang, Wei


    A star-shaped monodisperse conjugated macroelectrolyte grafted with cationic side chains, TrNBr, was designed, synthesized, and utilized as efficient electron-collecting cathode interlayers for inverted polymer solar cells. A neutral one composed of identical star-shaped conjugated backbone, TrOH, was also investigated for comparison. The surface properties and the function as interfacial layers on modulating the work function of bottom electrode (indium tin oxide) were systematically studied. Both interfacial electron-selective materials show strongly thickness-dependent performance for inverted polymer solar cells, and the best performance could be achieved via optimizing the thickness with 2.4 nm of TrNBr and 8.7 nm of TrOH. Parallel investigations of optimized TrNBr and TrOH interlayer in inverted architecture with active blend layer of poly(3-hexylthiophene):indene-C60 bisadduct (P3HT:ICBA) demonstrated a remarkable power conversion efficiency (PCE) enhancement (PCE of 4.88% for TrNBr and 4.74% for TrOH) in comparison with those of conventional noninverted devices using Ca/Al cathodes (3.94%) and inverted devices with sol-gel ZnO buffer layer (4.21%). In addition, the inverted devices using the TrNBr and TrOH interlayer exhibited improved device stability in contrast to conventional noninverted devices using Ca/Al cathodes.

  5. Isolation and Characterization of Well-Defined Silica-Supported Azametallacyclopentane: A Key Intermediate in Catalytic Hydroaminoalkylation Reactions

    KAUST Repository

    Hamzaoui, Bilel


    Intermolecular catalytic hydroaminoalkylation of unactivated alkene occurs with silica-supported azazirconacyclopropane [[TRIPLE BOND]Si[BOND]O[BOND]Zr(HNMe2)(η2-NMeCH2)(NMe2)]. Mechanistic studies were conducted using surface organometallic chemistry (SOMC) concepts to identify the key surface intermediates. The azametallacyclopentene intermediate {[TRIPLE BOND]Si[BOND]O[BOND]Zr(HNMe2)[η2-NMeCH2CH(Me)CH2](NMe2)} was isolated after treating with 1-propylene and characterized by FT-IR spectroscopy, elemental analysis, 1H 13C HETCOR, DARR SS-NMR and DQ TQ SS-NMR. The regeneration of the catalyst was conducted by dimethylamine protonolysis to yield the pure amine.

  6. Well-defined 2:1 and 2:2 arylcopper-copper bromide aggregates and selective biaryl formation

    NARCIS (Netherlands)

    Koten, G. van; Janssen, M.D.; Corsten, M.A.; Spek, A.L.; Grove, D.M.


    Reaction of tetranuclear [Li4(C6H4CH2NMe2-2)4] (1) with 4/3 equiv of the copper(I) arenethiolate [Cu3(SC6H4NMe2-2)3] (2) results in the quantitative formation of the arylcopper compound [Cu4(C6H4CH2NMe2-2)4] (3) and the lithium arenethiolate [Li(SC6H4NMe2-2)]n (4). The arylcopper species 3 is a

  7. In-depth analysis of protein inference algorithms using multiple search engines and well-defined metrics. (United States)

    Audain, Enrique; Uszkoreit, Julian; Sachsenberg, Timo; Pfeuffer, Julianus; Liang, Xiao; Hermjakob, Henning; Sanchez, Aniel; Eisenacher, Martin; Reinert, Knut; Tabb, David L; Kohlbacher, Oliver; Perez-Riverol, Yasset


    In mass spectrometry-based shotgun proteomics, protein identifications are usually the desired result. However, most of the analytical methods are based on the identification of reliable peptides and not the direct identification of intact proteins. Thus, assembling peptides identified from tandem mass spectra into a list of proteins, referred to as protein inference, is a critical step in proteomics research. Currently, different protein inference algorithms and tools are available for the proteomics community. Here, we evaluated five software tools for protein inference (PIA, ProteinProphet, Fido, ProteinLP, MSBayesPro) using three popular database search engines: Mascot, X!Tandem, and MS-GF+. All the algorithms were evaluated using a highly customizable KNIME workflow using four different public datasets with varying complexities (different sample preparation, species and analytical instruments). We defined a set of quality control metrics to evaluate the performance of each combination of search engines, protein inference algorithm, and parameters on each dataset. We show that the results for complex samples vary not only regarding the actual numbers of reported protein groups but also concerning the actual composition of groups. Furthermore, the robustness of reported proteins when using databases of differing complexities is strongly dependant on the applied inference algorithm. Finally, merging the identifications of multiple search engines does not necessarily increase the number of reported proteins, but does increase the number of peptides per protein and thus can generally be recommended. Protein inference is one of the major challenges in MS-based proteomics nowadays. Currently, there are a vast number of protein inference algorithms and implementations available for the proteomics community. Protein assembly impacts in the final results of the research, the quantitation values and the final claims in the research manuscript. Even though protein inference is a crucial step in proteomics data analysis, a comprehensive evaluation of the many different inference methods has never been performed. Previously Journal of proteomics has published multiple studies about other benchmark of bioinformatics algorithms (PMID: 26585461; PMID: 22728601) in proteomics studies making clear the importance of those studies for the proteomics community and the journal audience. This manuscript presents a new bioinformatics solution based on the KNIME/OpenMS platform that aims at providing a fair comparison of protein inference algorithms ( Six different algorithms - ProteinProphet, MSBayesPro, ProteinLP, Fido and PIA- were evaluated using the highly customizable workflow on four public datasets with varying complexities. Five popular database search engines Mascot, X!Tandem, MS-GF+ and combinations thereof were evaluated for every protein inference tool. In total >186 proteins lists were analyzed and carefully compare using three metrics for quality assessments of the protein inference results: 1) the numbers of reported proteins, 2) peptides per protein, and the 3) number of uniquely reported proteins per inference method, to address the quality of each inference method. We also examined how many proteins were reported by choosing each combination of search engines, protein inference algorithms and parameters on each dataset. The results show that using 1) PIA or Fido seems to be a good choice when studying the results of the analyzed workflow, regarding not only the reported proteins and the high-quality identifications, but also the required runtime. 2) Merging the identifications of multiple search engines gives almost always more confident results and increases the number of peptides per protein group. 3) The usage of databases containing not only the canonical, but also known isoforms of proteins has a small impact on the number of reported proteins. The detection of specific isoforms could, concerning the question behind the study, compensate for slightly shorter reports using the parsimonious reports. 4) The current workflow can be easily extended to support new algorithms and search engine combinations. Copyright © 2016. Published by Elsevier B.V.

  8. The antibody response to well-defined malaria antigens after acute malaria in individuals living under continuous malaria transmission

    DEFF Research Database (Denmark)

    Petersen, E; Høgh, B; Dziegiel, Morten Hanefeld


    the antigens, the responses were often short-lived. In adults, the antibody responses to the GLURP489-1271 fusion protein and the (EENV)6 peptide peaked after 2 weeks, and not all individuals responded to all antigens. The antibody response, even against large fragments of conserved antigens, is not uniformly......The IgG and IgM antibody responses to the C-terminal 783 amino acids of the P. falciparum glutamate-rich protein, GLURP489-1271, expressed as an E. coli fusion protein, the IgG response to a 18-mer synthetic peptide EDKNEKGQHEIVEVEEIL (GLURP899-916) representing the C-terminal repeats of GLURP......, and a synthetic peptide (EENV)6 representing the C-terminal repeats from Pf155/RESA, were investigated longitudinally in 13 children and 7 adults living under conditions of continuous, intense malaria transmission. Some subjects did not recognize the antigens after malaria infection, and in subjects recognizing...

  9. Photodeposition of platinum nanoparticles on well-defined Tungsten oxide: controlling oxidation state, particle size and geometrical distribution

    NARCIS (Netherlands)

    Wenderich, Kasper


    In this thesis, structure-directed photodeposition of the cocatalyst platinum (Pt) on monoclinic tungsten oxide (WO3) nanoplates is described, both considering fundamental aspects, as well as usefulness for applications in photocatalytic propane oxidation. Before such studies are described, the

  10. Overcoming the PEG-addiction: well-defined alternatives to PEG, from structure–property relationships to better defined therapeutics

    KAUST Repository

    Barz, Matthias


    Synthetic methods in polymer chemistry have evolved tremendously during the last decade. Nowadays more and more attention is devoted to the application of those tools in the development of the next generation of nanomedicines. Nevertheless, poly(ethylene glycol) (PEG) remains the most frequently used polymer for biomedical applications. In this review, we try to summarize recent efforts and developments in controlled polymerisation techniques that may allow alternatives to PEG based systems and can be used to improve the properties of future polymer therapeutics. © 2011 The Royal Society of Chemistry.

  11. Well-defined inorganic/organic nanocomposite by nano silica core-poly(methyl methacrylate/butylacrylate/trifluoroethyl methacrylate) shell. (United States)

    Chang, Gang; He, Ling; Zheng, Wei; Pan, Aizhao; Liu, Jing; Li, Yingjun; Cao, Ruijun


    The novel inorganic/organic core-shell SiO2/P(MMA/BA/3FMA) nanocomposite for coating application is synthesized in this paper by seed emulsion polymerization, in which the inorganic phase is composed of nano-SiO2 modified by vinyl-trimethoxysilane (VMS) or γ-methacryloxy propyl trimethoxylsilane (MPMS), and the organic phase is made of terpolymer by 2,2,2-trifluoroethyl methacrylate (3FMA), methyl methacrylate (MMA), and n-butyl acrylate (BA). The chemical structure of SiO2/P(MMA/BA/3FMA) is characterized by FTIR. The effect of surfactant polyvinylpyrrolidone (PVP), sodium dodecyl sulfate (SDS)/octyl phenyl polyoxyethylene ether (TX-10), sodium dodecyl benzene sulfonate (SDBS)/TX-10 and sodium hexametaphosphate (SHMP) on the grafting ratio (GR) of VMS and MPMS, the dispersion of nano-SiO2 particles and the film properties of SiO2/P(MMA/BA/3FMA) are investigated by TGA, DLS, TEM, SEM, and XPS. The morphology variation and the particle size distributions of SiO2/P(MMA/BA/3FMA) with the content of surfactant and P(MMA/BA/3FMA) are characterized. It is found that MPMS is more effective than VMS in improving GR and the dispersion of nano-SiO2 particles. The surfactants are favor of gaining the higher GR in the multilayer grafted nano-SiO2, especially SDS/TX-10 for 17.6% GR. The morphology of SiO2/P(MMA/BA/3FMA) is controlled by the amount of SDS/TX-10 and P(MMA/BA/3FMA) as the core-shell particles, the stacked pomegranate seed with multicore and the multicore-single shell structure when w(MMA)/w(BA)/w(3FMA)=1.3/1/1. Among the different surfactants, SDBS/TX-10 and PVP could give the monodispersing nano-SiO2 in the terpolymer matrix of the films, but SDS/TX-10 and SDBS/TX-10 could perform the fluorine-rich surface. Crown Copyright © 2013. Published by Elsevier Inc. All rights reserved.

  12. The antibody response to well-defined malaria antigens after acute malaria in individuals living under continuous malaria transmission

    DEFF Research Database (Denmark)

    Petersen, E; Høgh, B; Dziegiel, M


    , and a synthetic peptide (EENV)6 representing the C-terminal repeats from Pf155/RESA, were investigated longitudinally in 13 children and 7 adults living under conditions of continuous, intense malaria transmission. Some subjects did not recognize the antigens after malaria infection, and in subjects recognizing...... elicited by natural malaria infection in previously primed donors....

  13. Modification of Ti6Al4V substrates with well-defined zwitterionic polysulfobetaine brushes for improved surface mineralization. (United States)

    Liu, Pingsheng; Domingue, Emily; Ayers, David C; Song, Jie


    Osteoconductive mineral coatings are beneficial for improving the osteointegration of metallic orthopedic/dental implants, but achieving adequate structural integration between the surface minerals and underlying metallic substrates has been a significant challenge. Here, we report covalent grafting of zwitterionic poly(sulfobetaine methacrylate) (pSBMA) brushes on the Ti6Al4V substrates to promote the surface-mineralization of hydroxyapatite with enhanced surface mineral coverage and mineral-substrate interfacial adhesion. We first optimized the atom transfer radical polymerization (ATRP) conditions for synthesizing pSBMA polymers in solution. Well-controlled pSBMA polymers (relative molecular weight up to 26 kD, PDI = 1.17) with high conversions were obtained when the ATRP was carried out in trifluoroethanol/ionic liquid system at 60 °C. Applying identical polymerization conditions, surface-initiated atom transfer radical polymerization (SI-ATRP) was carried out to graft zwitterionic pSBMA brushes (PDI Ti6Al4V substrates, generating a stable superhydrophilic and low-fouling surface coating without compromising the bulk mechanic property of the Ti6Al4V substrates. The zwitterionic pSBMA surface brushes, capable of attracting both cationic and anionic precursor ions during calcium phosphate apatite mineralization, increased the surface mineral coverage from 32% to 71%, and significantly reinforced the attachment of the apatite crystals on the Ti6Al4V substrate. This facile approach to surface modification of metallic substrates can be exploited to generate multifunctional polymer coatings and improve the performance of metallic implants in skeletal tissue engineering and orthopedic and dental care.

  14. Quality-controlled small-scale production of a well-defined bacteriophage cocktail for use in human clinical trials.

    Directory of Open Access Journals (Sweden)

    Maya Merabishvili

    Full Text Available We describe the small-scale, laboratory-based, production and quality control of a cocktail, consisting of exclusively lytic bacteriophages, designed for the treatment of Pseudomonas aeruginosa and Staphylococcus aureus infections in burn wound patients. Based on successive selection rounds three bacteriophages were retained from an initial pool of 82 P. aeruginosa and 8 S. aureus bacteriophages, specific for prevalent P. aeruginosa and S. aureus strains in the Burn Centre of the Queen Astrid Military Hospital in Brussels, Belgium. This cocktail, consisting of P. aeruginosa phages 14/1 (Myoviridae and PNM (Podoviridae and S. aureus phage ISP (Myoviridae was produced and purified of endotoxin. Quality control included Stability (shelf life, determination of pyrogenicity, sterility and cytotoxicity, confirmation of the absence of temperate bacteriophages and transmission electron microscopy-based confirmation of the presence of the expected virion morphologic particles as well as of their specific interaction with the target bacteria. Bacteriophage genome and proteome analysis confirmed the lytic nature of the bacteriophages, the absence of toxin-coding genes and showed that the selected phages 14/1, PNM and ISP are close relatives of respectively F8, phiKMV and phage G1. The bacteriophage cocktail is currently being evaluated in a pilot clinical study cleared by a leading Medical Ethical Committee.

  15. Growth, characterization, and application of well-defined separated GaN-based pyramid array on micropatterned sapphire substrate (United States)

    Tian, Zhenhuan; Li, Yufeng; Su, Xilin; Feng, Lungang; Wang, Shuai; Zhang, Minyan; Ding, Wen; Li, Qiang; Zhang, Ye; Guo, Maofeng; Yun, Feng; Lee, S. W. Ricky


    We tried to obtain microstructures on a three-dimensional (3D) micropatterned substrate by laser drilling. The influences of the dimensions of the drilling holes on the morphology and the material quality of the grown structures were studied. Uniform micropyramid arrays with relatively low dislocation density can be achieved by adjusting the laser drilling parameters. The internal quantum efficiency was estimated to be improved by a factor of 3 for a pyramid structure compared with that of planar LEDs. We fabricated 5 × 7 mm2 flexible LEDs employing the pyramid structure and the devices exhibited good flexibility without performance reduction after bending.

  16. Gold Nanoparticles on Layered Double Hydroxide Nanosheets and Its Electrocatalysis for Glucose Oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Hye Ran; Lee, Jong Hyeon [The Catholic University of Korea, Bucheon (Korea, Republic of); Cho, Se Hee; Ji, Hong Geun [H and A PharmaChem, Bucheon (Korea, Republic of)


    We developed a new way to form the well-defined nanocomposite of Au NPs and exfoliated LDH nanosheet by in situ chemical reduction with NaBH{sub 4}. The optical and structural studies indicate that the Au NPs are highly dispersed and immobilized on the surface of LDH nanosheets. The Au/LDH nanosheet exhibited an excellent electrocatalysis toward glucose oxidation reaction. The results strongly demonstrate that the nanoscopic natures and dense positive charges of LDH nanosheet effectively stabilized the Au NPs to maintain their inherent properties during the synthesis and the electrocatalysis. The use of the double hydroxide nanosheets as nanoscopic support materials for the transition-metal NPs will dramatically improve their functionalities in heterogeneous catalysis. Recently, two-dimensional nanosheet of exfoliated layered double hydroxide (LDH) has emerged as a new type of solid support to immobilize the diverse metal NPs because of the large metal hydroxide area, good biochemical stability, and highly charged positive potential of 1- to 2-nm thick LDH layers. LDHs consist of a continuous stack of positively charged metal hydroxide layers with counter anions and water molecules placed in interlayer spaces.

  17. Experiments on double beta decay

    Energy Technology Data Exchange (ETDEWEB)

    Busto, J. [Neuchatel Univ. (Switzerland). Inst. de Physique


    The Double Beta Decay, and especially ({beta}{beta}){sub 0{nu}} mode, is an excellent test of Standard Model as well as of neutrino physics. From experimental point of view, a very large number of different techniques are or have been used increasing the sensitivity of this experiments quite a lot (the factor of 10{sup 4} in the last 20 years). In future, in spite of several difficulties, the sensitivity would be increased further, keeping the interest of this very important process. (author) 4 figs., 5 tabs., 21 refs.

  18. Reconfigurable Double-Curved Mould

    DEFF Research Database (Denmark)

    Raun, Christian; Kirkegaard, Poul Henning


    , double curved surfaces like facades or walls, where the curvature of each element is relatively small in comparison to the overall shape. In the proposed dynamic mould system, where only a set of points is defined, a stiff membrane interpolates the surface between points. To function as a surface...... suitable for casting concrete or other substances against without the need for further manual treatment, the membrane should be durable and maintain a perfectly smooth and non-porous surface as well. A membrane with these properties has been developed for this project, and it is the core of the dynamic...

  19. Booster Double Harmonic Setup Notes

    Energy Technology Data Exchange (ETDEWEB)

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


    The motivation behind implementing a booster double harmonic include the reduced transverse space charge force from a reduced peak beam current and reduced momentum spread of the beam, both of which can be achieved from flattening the RF bucket. RF capture and acceleration of polarized protons (PP) is first set up in the single harmonic mode with RF harmonic h=1. Once capture and acceleration have been set up in the single harmonic mode, the second harmonic system is brought on and programmed to operate in concert with the single harmonic system.

  20. Double breast contour in primary aesthetic breast augmentation: incidence, prevention and treatment. (United States)

    Médard de Chardon, Victor; Balaguer, Thierry; Chignon-Sicard, Bérengère; Lebreton, Elisabeth


    , physiopathogeny, prevention and treatment. Type I major risk factor is subpectoral augmentation of ptotic breasts (with medium to bad skin quality and loses muscle to gland attachments). The muscle at the inferior pole of the breast is a "brake" preventing implant to fill the envelope. This risk is increased with implant malposition, constitutional ptosis asymmetry with symmetrical implant placement and selection of an insufficient implant projection or dimensions. This deformity can be avoided with selection of a subglandular or dual plane (type II or III) placement, a sufficient implant volume or projection and anatomic prosthesis. Type II is related to a lowering of a well-defined submammary fold more commonly in constricted and dens glandular breasts. This deformity can be avoided with respecting the inframammary fold, radial incisions on the gland's posterior surface, and selection of anatomic implants.

  1. Challenges in Double Beta Decay

    Directory of Open Access Journals (Sweden)

    Oliviero Cremonesi


    Full Text Available In the past ten years, neutrino oscillation experiments have provided the incontrovertible evidence that neutrinos mix and have finite masses. These results represent the strongest demonstration that the electroweak Standard Model is incomplete and that new Physics beyond it must exist. In this scenario, a unique role is played by the Neutrinoless Double Beta Decay searches which can probe lepton number conservation and investigate the Dirac/Majorana nature of the neutrinos and their absolute mass scale (hierarchy problem with unprecedented sensitivity. Today Neutrinoless Double Beta Decay faces a new era where large-scale experiments with a sensitivity approaching the so-called degenerate-hierarchy region are nearly ready to start and where the challenge for the next future is the construction of detectors characterized by a tonne-scale size and an incredibly low background. A number of new proposed projects took up this challenge. These are based either on large expansions of the present experiments or on new ideas to improve the technical performance and/or reduce the background contributions. In this paper, a review of the most relevant ongoing experiments is given. The most relevant parameters contributing to the experimental sensitivity are discussed and a critical comparison of the future projects is proposed.

  2. Dynamical Aspects of Electrostatic Double Layers

    DEFF Research Database (Denmark)

    Raadu, M.A.; Juul Rasmussen, J.


    Electrostatic double layers have been proposed as an acceleration mechanism in solar flares and other astrophysical objects. They have been extensively studied in the laboratory and by means of computer simulations. The theory of steady-state double layers implies several existence criteria...... plasma, at least for strong double layers, and it is argued that such conditions must be used with care when applied to real plasmas. Laboratory double layers, and by implication those arising in astrophysical plasmas often produce instabilities in the surrounding plasma and are generally time......-dependent structures. Naturally occuring double layers should, therefore, be far more common than the restrictions deduced from idealised time-independent models would imply. In particular it is necessary to understand more fully the time-dependent behaviour of double layers. In the present paper the dynamics of weak...

  3. Double Dirac cones in phononic crystals

    KAUST Repository

    Li, Yan


    A double Dirac cone is realized at the center of the Brillouin zone of a two-dimensional phononic crystal (PC) consisting of a triangular array of core-shell-structure cylinders in water. The double Dirac cone is induced by the accidental degeneracy of two double-degenerate Bloch states. Using a perturbation method, we demonstrate that the double Dirac cone is composed of two identical and overlapping Dirac cones whose linear slopes can also be accurately predicted from the method. Because the double Dirac cone occurs at a relatively low frequency, a slab of the PC can be mapped onto a slab of zero refractive index material by using a standard retrieval method. Total transmission without phase change and energy tunneling at the double Dirac point frequency are unambiguously demonstrated by two examples. Potential applications can be expected in diverse fields such as acoustic wave manipulations and energy flow control.

  4. Optics design for CEPC double ring scheme (United States)

    Wang, Yiwei; Su, Feng; Bai, Sha; Yu, Chenghui; Gao, Jie


    The CEPC is a future Circular Electron and Positron Collider proposed by China to mainly study the Higgs boson. Its baseline design is a double ring scheme and an alternative design is a partial double ring scheme. This paper will present the optics design for the main ring of the double ring scheme. The CEPC will also work as a W and Z factory. Compatible optics designs for a W and a Z modes will be presented as well.

  5. Double Helix Nodal Line Superconductor (United States)

    Sun, Xiao-Qi; Lian, Biao; Zhang, Shou-Cheng


    Time-reversal invariant superconductors in three dimensions may contain nodal lines in the Brillouin zone, which behave as Wilson loops of 3D momentum-space Chern-Simons theory of the Berry connection. Here we study the conditions of realizing linked nodal lines (Wilson loops), which yield a topological contribution to the thermal magnetoelectric coefficient that is given by the Chern-Simons action. We find the essential conditions are the existence of torus or higher genus Fermi surfaces and spiral spin textures. We construct such a model with two torus Fermi surfaces, where a generic spin-dependent interaction leads to double-helix-like linked nodal lines as the superconductivity is developed.

  6. CERN celebrates a double anniversary

    CERN Multimedia


    A symposium will celebrate the double anniversary of the observation of neutral currents in 1973 and the discovery of W and Z bosons in 1983. The symposium will also provide an opportunity to discuss future discoveries at CERN. The symposium will be held on 16 September in the Main Auditorium from 9:00 hrs and will be open to the public. If you cannot access the Main Auditorium, the symposium will be broadcast live in the following conference rooms: AB Auditorium II (Bldg 864) in Prévessin IT Auditorium (Bldg 31) AT Auditorium (Bldg 30) You can also follow it online with the Webcast accessible from the CERN home page. See the complete programme under Seminars.

  7. Double Helix Nodal Line Superconductor. (United States)

    Sun, Xiao-Qi; Lian, Biao; Zhang, Shou-Cheng


    Time-reversal invariant superconductors in three dimensions may contain nodal lines in the Brillouin zone, which behave as Wilson loops of 3D momentum-space Chern-Simons theory of the Berry connection. Here we study the conditions of realizing linked nodal lines (Wilson loops), which yield a topological contribution to the thermal magnetoelectric coefficient that is given by the Chern-Simons action. We find the essential conditions are the existence of torus or higher genus Fermi surfaces and spiral spin textures. We construct such a model with two torus Fermi surfaces, where a generic spin-dependent interaction leads to double-helix-like linked nodal lines as the superconductivity is developed.

  8. The concept of double inlet-double outlet right ventricle: a distinct congenital heart disease


    Spadotto, V; Frescura, C; Ho, SY; Thiene, G


    The aim of this study was to estimate the incidence and to analyze the anatomy of double inlet-double outlet right ventricle complex and its associated cardiac anomalies in our autopsy series. Among the 1640 hearts with congenital heart disease of our Anatomical Collection, we reviewed the specimens with double inlet-double outlet right ventricle, according to the sequential-segmental analysis, identifying associated cardiac anomalies and examining lung histology to assess the presence of pul...

  9. Double meanings will not save the principle of double effect. (United States)

    Douglas, Charles D; Kerridge, Ian H; Ankeny, Rachel A


    In an article somewhat ironically entitled "Disambiguating Clinical Intentions," Lynn Jansen promotes an idea that should be bewildering to anyone familiar with the literature on the intention/foresight distinction. According to Jansen, "intention" has two commonsense meanings, one of which is equivalent to "foresight." Consequently, questions about intention are "infected" with ambiguity-people cannot tell what they mean and do not know how to answer them. This hypothesis is unsupported by evidence, but Jansen states it as if it were accepted fact. In this reply, we make explicit the multiple misrepresentations she has employed to make her hypothesis seem plausible. We also point out the ways in which it defies common sense. In particular, Jansen applies her thesis only to recent empirical research on the intentions of doctors, totally ignoring the widespread confusion that her assertion would imply in everyday life, in law, and indeed in religious and philosophical writings concerning the intention/foresight distinction and the Principle of Double Effect. © The Author 2014. Published by Oxford University Press, on behalf of the Journal of Medicine and Philosophy Inc. All rights reserved. For permissions, please e-mail:

  10. Finite difference order doubling in two dimensions

    Energy Technology Data Exchange (ETDEWEB)

    Killingbeck, John P [Mathematics Centre, University of Hull, Hull HU6 7RX (United Kingdom); Jolicard, Georges [Universite de Franche-Comte, Institut Utinam (UMR CNRS 6213), Observatoire de Besancon, 41 bis Avenue de l' Observatoire, BP1615, 25010 Besancon cedex (France)


    An order doubling process previously used to obtain eighth-order eigenvalues from the fourth-order Numerov method is applied to the perturbed oscillator in two dimensions. A simple method of obtaining high order finite difference operators is reported and an odd parity boundary condition is found to be effective in facilitating the smooth operation of the order doubling process.

  11. Double Chooz and Reactor Theta13 Experiments

    CERN Document Server



    This is a contribution paper from the Double Chooz experiment to the special issue of NPB on neutrino oscillations. The physics and history of the reactor theta13 experiments, as well as Double Chooz experiment and its neutrino oscillation analyses are reviewed.

  12. Modelling the formation of double white dwarfs

    NARCIS (Netherlands)

    van der Sluijs, M.V.; Verbunt, F.W.M.|info:eu-repo/dai/nl/068970374; Pols, O.|info:eu-repo/dai/nl/111811155


    We investigate the formation of the ten double-lined double white dwarfs that have been observed so far. A detailed stellar evolution code is used to calculate grids of single-star and binary models and we use these to reconstruct possible evolutionary scenarios. We apply various criteria to select

  13. The homozygosity verification for doubled haploid Japanese ...

    African Journals Online (AJOL)



    Sep 18, 2012 ... coefficients of variation of doubled haploids were significantly higher than those of normal diploids. Key words: Doubled haploids, gynogenesis, Japanese flounder, Paralichthys olivaceus. INTRODUCTION. Mitotic gynogenesis in fish has been used to produce completely homozygous progenies (Thorgaad ...

  14. 7 CFR 3560.460 - Double damages. (United States)


    ... DIRECT MULTI-FAMILY HOUSING LOANS AND GRANTS Special Servicing, Enforcement, Liquidation, and Other Actions § 3560.460 Double damages. (a) Action to recover assets or income. (1) The Agency may request to... 7 Agriculture 15 2010-01-01 2010-01-01 false Double damages. 3560.460 Section 3560.460 Agriculture...

  15. Double pulse Thomson scattering system at RTP

    NARCIS (Netherlands)

    Beurskens, M. N. A.; Barth, C. J.; Chu, C.C.; Donne, A. J. H.; Herranz, J. A.; Cardozo, N. J. L.; van der Meiden, H. J.; Pijper, F.J.


    In this article a double pulse multiposition Thomson scattering diagnostic, under construction at RTP, is discussed. Light from a double pulsed ruby laser (pulse separation: 10-800 mu s, max. 2x12.5 J) is scattered by the free electrons of the tokamak plasma and relayed to a Littrow polychromator

  16. Intrateam Communication and Performance in Doubles Tennis (United States)

    Lausic, Domagoj; Tennebaum, Gershon; Eccles, David; Jeong, Allan; Johnson, Tristan


    Verbal and nonverbal communication is a critical mediator of performance in team sports and yet there is little extant research in sports that involves direct measures of communication. Our study explored communication within NCAA Division I female tennis doubles teams. Video and audio recordings of players during doubles tennis matches captured…

  17. Three Dimensional Double Layers in Magnetized Plasmas

    DEFF Research Database (Denmark)

    Jovanovic, D.; Lynov, Jens-Peter; Michelsen, Poul


    Experimental results are presented which demonstrate the formation of fully three dimensional double layers in a magnetized plasma. The measurements are performed in a magnetized stationary plasma column with radius 1.5 cm. Double layers are produced by introducing an electron beam with radius 0...

  18. The Sexual Double Standard: How Prevalent Today? (United States)

    Sack, Alan R.; And Others


    Studied the sexual double standard among university students. Females showed a stronger association between premarital intercourse and affection and perceived less approval from five reference groups for their sexual behavior than did males. Results indicate the sexual double standard is still evident among the present group of college students.…

  19. The Doubling Moment: Resurrecting Edgar Allan Poe (United States)

    Minnick, J. Bradley; Mergil, Fernando


    This article expands upon Jeffrey Wilhelm's and Brian Edmiston's (1998) concept of a doubling of viewpoints by encouraging middle level students to use dramatization to take on multiple perspectives, to pose interpretive questions, and to enhance critical inquiry from inside and outside of texts. The doubling moment is both the activation of…

  20. Reliability Estimation for Double Containment Piping

    Energy Technology Data Exchange (ETDEWEB)

    L. Cadwallader; T. Pinna


    Double walled or double containment piping is considered for use in the ITER international project and other next-generation fusion device designs to provide an extra barrier for tritium gas and other radioactive materials. The extra barrier improves confinement of these materials and enhances safety of the facility. This paper describes some of the design challenges in designing double containment piping systems. There is also a brief review of a few operating experiences of double walled piping used with hazardous chemicals in different industries. This paper recommends approaches for the reliability analyst to use to quantify leakage from a double containment piping system in conceptual and more advanced designs. The paper also cites quantitative data that can be used to support such reliability analyses.

  1. Agreement, dominance and doubling : the morphosyntax of DP

    NARCIS (Netherlands)

    Schoorlemmer, Erik


    This thesis investigates doubling and agreement in Romance and Germanic nominal constituents. In Swedish, Norwegian, and Faroese, the definite article is doubled in case an adjective modifies the noun. This doubling is known as double definiteness. This thesis proposes that double definiteness is

  2. Double layers in contactor plasmas (United States)

    Cooke, David L.


    The concept of using a hollow cathode to establish a low impedance contact between a spacecraft and the ambient plasma continues to gain in popularity, and is often then referred to as a plasma contactor. A growing number of studies indicate that large contact currents can be supported with small potential difference between the contactor and the ambient plasma. Results will be presented from a simple one-dimensional spherical model that obtains potentials from the solution of Poisson's equation, and particle densities from a turning point formalism that includes particle angular momentum. The neglect of collisions and magnetic field limits the realism. However, the results illustrate the effect of double layers that can form at the interface between contactor and ambient plasmas, when there is any voltage differential between the contactor and the ambient. The I-V characteristic of this model shows the usual space charge depends upon collection when the contactor flux is lower than some threshold; independence of I from variation in V when the flux is slightly greater than that threshold, and (numerical ?) instability for excessive flux suggesting the possibility of negative resistance. Even if a real I-V characteristic does not exhibit negative resistance, flat spots or high resistance regions may still be troublesome (or useful) to the total circuit.

  3. Contact double-contrast cholangiography. (United States)

    Hishida, Y


    Recently operative cholangiography has become an essential step in biliary surgery. However, an usual technique in which x-ray film is set beneath the patient has its limitation in visualization of fine changes. The author devised a new technique to resolve this problem. A triangular mammography film designed for good positioning is vaccum-packed, coupled with an intensifying screen of the same size, and then is sterilized in advance. Barium solution mixed with Gascon drop (a defoaming agent) is used as contrast material. The duodenum and head of the pancreas are mobilized. Usual cholangiography is performed at first, introducing angiographic media through a catheter placed into the catheter placed into the common duct via the cystic duct. After this study a triangle film pack is set beneath the second part of the duodenum. Two to three milliliters of barium, 1 to 2 ml of Gascon, and 15 ml of air are pushed in; thus a contact double-contrast cholangiogram is obtained. This technique promises clear demonstration of the distal bile duct without risk, and even fine mucosal plicae may be discernible in the film.

  4. Renormalization of minimally doubled fermions (United States)

    Capitani, Stefano; Creutz, Michael; Weber, Johannes; Wittig, Hartmut


    We investigate the renormalization properties of minimally doubled fermions, at one loop in perturbation theory. Our study is based on the two particular realizations of Boriçi-Creutz and Karsten-Wilczek. A common feature of both formulations is the breaking of hyper-cubic symmetry, which requires that the lattice actions are supplemented by suitable counterterms. We show that three counterterms are required in each case and determine their coefficients to one loop in perturbation theory. For both actions we compute the vacuum polarization of the gluon. It is shown that no power divergences appear and that all contributions which arise from the breaking of Lorentz symmetry are cancelled by the counterterms. We also derive the conserved vector and axial-vector currents for Karsten-Wilczek fermions. Like in the case of the previously studied Boriçi-Creutz action, one obtains simple expressions, involving only nearest-neighbour sites. We suggest methods how to fix the coefficients of the counterterms non-perturbatively and discuss the implications of our findings for practical simulations.

  5. Indefinite Determiner Doubling: Data and Methods

    DEFF Research Database (Denmark)

    Wood, Johanna; Vikner, Sten


    , and double definiteness, found in some Scandinavian languages. In this chapter, we focus on doubling of indefinite determiners in the Germanic languages, that is, on nominal expressions in which the indefinite article occurs more than once within the same DP (determiner phrase, i.e. nominal expression).......Syntactic doubling, expressing a constituent twice (or more) when a single occurrence should suffice, is surprisingly common, especially where functional elements are concerned (Barbiers 2008:5). Some well-known examples include multiple negation/negative concord, found in many languages...

  6. Double-reed exhaust valve engine (United States)

    Bennett, Charles L.


    An engine based on a reciprocating piston engine that extracts work from pressurized working fluid. The engine includes a double reed outlet valve for controlling the flow of low-pressure working fluid out of the engine. The double reed provides a stronger force resisting closure of the outlet valve than the force tending to open the outlet valve. The double reed valve enables engine operation at relatively higher torque and lower efficiency at low speed, with lower torque, but higher efficiency at high speed.

  7. The Dissolution of Double Holliday Junctions

    DEFF Research Database (Denmark)

    Bizard, Anna H; Hickson, Ian D


    as "double Holliday junction dissolution." This reaction requires the cooperative action of a so-called "dissolvasome" comprising a Holliday junction branch migration enzyme (Sgs1/BLM RecQ helicase) and a type IA topoisomerase (Top3/TopoIIIα) in complex with its OB (oligonucleotide/oligosaccharide binding......Double Holliday junctions (dHJS) are important intermediates of homologous recombination. The separate junctions can each be cleaved by DNA structure-selective endonucleases known as Holliday junction resolvases. Alternatively, double Holliday junctions can be processed by a reaction known...

  8. Doubling left syntactic positions in Danish

    DEFF Research Database (Denmark)

    Jørgensen, Henrik


    This paper deals with the doubling of left syntactic positions in Danish. Such doublings consist of a referential element: a NP or a clause, and an anaphoric element, an unstressed personal pronoun or an unstressed resumptive adverb. In main clauses, the CP-spec position may double in this way, w...... in the analysis of a broadcasted public speech (sect. 5). In earlier versions of Danish, as shown in sect. 4, the construction is both more frequent in writing and also seems almost obligatory....

  9. Positivity bounds on double parton distributions

    Energy Technology Data Exchange (ETDEWEB)

    Diehl, Markus; Kasemets, Tomas


    Double hard scattering in proton-proton collisions is described in terms of double parton distributions. We derive bounds on these distributions that follow from their interpretation as probability densities, taking into account all possible spin correlations between two partons in an unpolarized proton. These bounds constrain the size of the polarized distributions and can for instance be used to set upper limits on the effects of spin correlations in double hard scattering. We show that the bounds are stable under leading-order DGLAP evolution to higher scales.

  10. Electric double layer and electrokinetic potential of pectic macromolecules in sugar beet

    Directory of Open Access Journals (Sweden)

    Kuljanin Tatjana A.


    Full Text Available Electrokinetic potential is an important property of colloidal particles and, regarding the fact that it is a well defined and easily measurable property, it is considered to be a permanent characteristic of a particular colloidal system. In fact, it is a measure of electrokinetic charge that surrounds the colloidal particle in a solution and is in direct proportion with the mobility of particles in an electric field. Gouy-Chapman-Stern-Graham's model of electric double layer was adopted and it was proven experimentally that the addition of Cu++ ions to sugar beet pectin caused a reduction in the negative electrokinetic potential proportional to the increase of Cu++ concentration. Higher Cu++ concentrations increased the proportion of cation specific adsorption (Cu++ and H+ with regard to electrostatic Coulombic forces. Consequently, there is a shift in the shear plane between the fixed and diffuse layers directed towards the diffuse layer, i.e. towards its compression and decrease in the electrokinetic potential or even charge inversion of pectin macromolecules.

  11. Nuclear magnetic resonance diffusion pore imaging: Experimental phase detection by double diffusion encoding. (United States)

    Demberg, Kerstin; Laun, Frederik Bernd; Windschuh, Johannes; Umathum, Reiner; Bachert, Peter; Kuder, Tristan Anselm


    Diffusion pore imaging is an extension of diffusion-weighted nuclear magnetic resonance imaging enabling the direct measurement of the shape of arbitrarily formed, closed pores by probing diffusion restrictions using the motion of spin-bearing particles. Examples of such pores comprise cells in biological tissue or oil containing cavities in porous rocks. All pores contained in the measurement volume contribute to one reconstructed image, which reduces the problem of vanishing signal at increasing resolution present in conventional magnetic resonance imaging. It has been previously experimentally demonstrated that pore imaging using a combination of a long and a narrow magnetic field gradient pulse is feasible. In this work, an experimental verification is presented showing that pores can be imaged using short gradient pulses only. Experiments were carried out using hyperpolarized xenon gas in well-defined pores. The phase required for pore image reconstruction was retrieved from double diffusion encoded (DDE) measurements, while the magnitude could either be obtained from DDE signals or classical diffusion measurements with single encoding. The occurring image artifacts caused by restrictions of the gradient system, insufficient diffusion time, and by the phase reconstruction approach were investigated. Employing short gradient pulses only is advantageous compared to the initial long-narrow approach due to a more flexible sequence design when omitting the long gradient and due to faster convergence to the diffusion long-time limit, which may enable application to larger pores.

  12. A realistic model of neutrino masses with a large neutrinoless double beta decay rate (United States)

    del Aguila, Francisco; Aparici, Alberto; Bhattacharya, Subhaditya; Santamaria, Arcadi; Wudka, Jose


    The minimal Standard Model extension with the Weinberg operator does accommodate the observed neutrino masses and mixing, but predicts a neutrinoless double beta (0 νββ) decay rate proportional to the effective electron neutrino mass, which can be then arbitrarily small within present experimental limits. However, in general 0 νββ decay can have an independent origin and be near its present experimental bound; whereas neutrino masses are generated radiatively, contributing negligibly to 0 νββ decay. We provide a realization of this scenario in a simple, well defined and testable model, with potential LHC effects and calculable neutrino masses, whose two-loop expression we derive exactly. We also discuss the connection of this model to others that have appeared in the literature, and remark on the significant differences that result from various choices of quantum number assignments and symmetry assumptions. In this type of models lepton flavor violating rates are also preferred to be relatively large, at the reach of foreseen experiments. Interestingly enough, in our model this stands for a large third mixing angle, {{si}}{{{n}}^{{2}}}{θ_{{{13}}}}{˜}}}{ > }}0.00{8} , when μ→ eee is required to lie below its present experimental limit.

  13. Estimation of pore size distribution using concentric double pulsed-field gradient NMR. (United States)

    Benjamini, Dan; Nevo, Uri


    Estimation of pore size distribution of well calibrated phantoms using NMR is demonstrated here for the first time. Porous materials are a central constituent in fields as diverse as biology, geology, and oil drilling. Noninvasive characterization of monodisperse porous samples using conventional pulsed-field gradient (PFG) NMR is a well-established method. However, estimation of pore size distribution of heterogeneous polydisperse systems, which comprise most of the materials found in nature, remains extremely challenging. Concentric double pulsed-field gradient (CDPFG) is a 2-D technique where both q (the amplitude of the diffusion gradient) and φ (the relative angle between the gradient pairs) are varied. A recent prediction indicates this method should produce a more accurate and robust estimation of pore size distribution than its conventional 1-D versions. Five well defined size distribution phantoms, consisting of 1-5 different pore sizes in the range of 5-25 μm were used. The estimated pore size distributions were all in good agreement with the known theoretical size distributions, and were obtained without any a priori assumption on the size distribution model. These findings support that in addition to its theoretical benefits, the CDPFG method is experimentally reliable. Furthermore, by adding the angle parameter, sensitivity to small compartment sizes is increased without the use of strong gradients, thus making CDPFG safe for biological applications. Copyright © 2013 Elsevier Inc. All rights reserved.

  14. On Double-Star Decomposition of Graphs

    Directory of Open Access Journals (Sweden)

    Akbari Saieed


    Full Text Available A tree containing exactly two non-pendant vertices is called a double-star. A double-star with degree sequence (k1 + 1, k2 + 1, 1, . . . , 1 is denoted by Sk1,k2. We study the edge-decomposition of graphs into double-stars. It was proved that every double-star of size k decomposes every 2k-regular graph. In this paper, we extend this result by showing that every graph in which every vertex has degree 2k + 1 or 2k + 2 and containing a 2-factor is decomposed into Sk1,k2 and Sk1−1,k2, for all positive integers k1 and k2 such that k1 + k2 = k.

  15. 32 CFR 199.8 - Double coverage. (United States)


    ... from the operation of a motor vehicle. (4) Exceptions. Double coverage plans do not include: (i) Plans... (for example, the Indian Health Service); or (v) State Victims of Crime Compensation Programs. (c...

  16. Period doubling patterns of interval maps

    CERN Document Server

    Valaristos, A


    We prove the existence and demonstrate the construction of period doubling patterns centered at periodic orbits of continuous maps on the interval. In particular we prove that f in R: =set membership C sup 0 (I,I) exhibits a period doubling pattern centered at a fixed point of f if and only if the set of periodic points is not closed. Furthermore, we prove that if f has a periodic orbit of period n>1, which is not a power of two, and n .pr. m in Sarkovskii's ordering, then f exhibits a period doubling pattern centered at a periodic orbit of period m. An analytic configuration of such period doubling patterns is exhibited.

  17. Over-under double-pass interferometer (United States)

    Schindler, Rudolf A. (Inventor)


    An over-under double-pass interferometer in which the beamsplitter area and thickness can be reduced to conform only with optical flatness considerations is achieved by offsetting the optical center line of one cat's-eye retroreflector relative to the optical center line of the other in order that one split beam be folded into a plane distinct from the other folded split beam. The beamsplitter is made transparent in one area for a first folded beam to be passed to a mirror for doubling back and is made totally reflective in another area for the second folded beam to be reflected to a mirror for doubling back. The two beams thus doubled back are combined in the central, beam-splitting area of the beamsplitter and passed to a detector. This makes the beamsplitter insensitive to minimum-thickness requirements and selection of material.

  18. Clitic doubling and pure agreement person features

    Directory of Open Access Journals (Sweden)

    Ricardo Machado Rocha


    Full Text Available In this paper, we analyze clitic doubling constructions in dialectal non-standard Brazilian Portuguese. Within the Minimalism Framework, we explain very peculiar aspects of the doubled structures in this language, namely the fact that they occur only for 1st and 2nd person pronouns and that they co-vary with single clitic structures and single strong pronoun structures. Our approach assumes that the clitics me and te are hosted by a dedicated functional projection and result from the checking of the sole person feature [speaker:±]. Moreover, we show that, unlikely other cross-linguistic phenomena of pronominal doubling, Brazilian Portuguese Clitic Doubling does neither yield (nor is a result of any interpretive effect, but rather is an instance of a pure agreement chain. This leads us to advocate, contra the standard Minimalist Program, for the validity of the conceptual postulation of AgrP, as a condition on well-formedness of certain structures.

  19. Double Heavy Flavour Production at LHCb

    CERN Document Server

    Li, Yiming


    This proceeding summarises the latest LHCb results on associated heavy flavour productions, including double charm production and associated bottomonia and charm production. This article belongs to the Topical Collection “New Observables in Quarkonium Production”.

  20. Rosalind Franklin and the Double Helix (United States)

    Elkin, Lynne Osman


    Although she made essential contributions toward elucidating the structure of DNA, Rosalind Franklin is known to many only as seen through the distorting lens of James Watson's book, The Double Helix.

  1. A High Power Frequency Doubled Fiber Laser (United States)

    Thompson, Rob; Tu, Meirong; Aveline, Dave; Lundblad, Nathan; Maleki, Lute


    This slide presentation reviews the power frequencies for the doubled fiber laser. It includes information on the 780 nm laser, second harmonic generation in one crystal, cascading crystals, the tenability of laser systems, laser cooling, and directions for future work.

  2. Forensic testing of a double tee bridge. (United States)


    This report describes an investigation to quantify the behavior of precast, prestressed concrete double-tee bridge : girders made with lightweight concrete. As part of the investigation, three bridge girders were salvaged from a : decommissioned brid...

  3. Inverse solutions for tilting orthogonal double prisms. (United States)

    Li, Anhu; Ding, Ye; Bian, Yongming; Liu, Liren


    An analytical reverse solution and actual examples are given to show how to direct a laser beam from a pair of orthogonal prisms to given targets in free space. Considering the influences of double-prism structural parameters, a lookup table method to seek the numerical reverse solution of each prism's tilting angle is also proposed for steering the double-prism orientation to track a target position located in the near field. Some case studies, as well as a specified elliptical target trajectory scanned by the cam-based driving double prisms, exhibit the significant application values of the theoretical derivation. The analytic reverse and numerical solutions can be generalized to investigate the synthesis of scanning patterns and the controlling strategy of double-prism tilting motion, the potentials of which can be explored to perform the orientation and position tracking functions in applications of precision engineering fields.

  4. Micropatterns of double-layered nanofiber scaffolds with dual functions of cell patterning and metabolite detection. (United States)

    Lee, Hyun Jong; Kim, Han-Soo; Kim, Hyun Ok; Koh, Won-Gun


    This paper describes the development of multi-functional nanofiber scaffolds consisting of multiple layers of nanofiber scaffolds and nanofiber-incorporated poly(ethylene glycol) (PEG) hydrogels. As a proof-of-concept demonstration, we fabricated micropatterned polymeric nanofiber scaffolds that were capable of simultaneously generating cellular micropatterns within a biomimetic environment and detecting cellular metabolic products within well-defined microdomains. To achieve this goal, we designed nanofiber scaffolds with both vertical and lateral microdomains. Vertically heterogeneous structures that were responsible for multi-functionality were realized by preparing double-layered nanofiber scaffolds consisting of an antibody-immobilized bottom layer of nanofibers and an upper layer of bare polystyrene (PS) nanofibers by a two-step sequential electrospinning process. Photopatterning of poly(ethylene glycol) (PEG) hydrogel on the electrospun nanofibers produced laterally heterogeneous micropatterned nanofiber scaffolds made of hydrogel microwells filled with a nanofibrous region, which is capable of generating cell and protein micropatterns due to the different interactions that cells and proteins have with PEG hydrogels and nanofibers. When HepG2 cells were seeded into resultant nanofiber scaffolds, cells selectively adhered within the 200 μm × 200 μm PS fiber microdomain and formed 180.2 ± 6.7 μm spheroids after 5 days of culture in the upper layer. Furthermore, immobilized anti-albumin in the bottom layer detected albumin secreted by micropatterned HepG2 cells with higher sensitivity than flat PS substrates, demonstrating successful accomplishment of dual functions using micropatterned double-layered nanofiber scaffolds.

  5. On the distribution of visual double stars

    Directory of Open Access Journals (Sweden)

    Angelov T.


    Full Text Available An integrated distribution function is derived for visual double stars according to the magnitude difference Δm between the components. For this purpose the author uses a sample of 1626 double stars with Δm ∈ [0m − 4m]. The increment of the descriptive distribution function for an arbitrary increment of the variable Δm is also determined.

  6. Conserved currents of double field theory

    Energy Technology Data Exchange (ETDEWEB)

    Blair, Chris D.A. [Department of Applied Mathematics and Theoretical Physics,Centre for Mathematical Sciences, University of Cambridge, Wilberforce Road, Cambridge CB3 0WA (United Kingdom)


    We find the conserved current associated to invariance under generalised diffeomorphisms in double field theory. This can be used to define a generalised Komar integral. We comment on its applications to solutions, in particular to the fundamental string/pp-wave. We also discuss the current in the context of Scherk-Schwarz compactifications. We calculate the current for both the original double field theory action, corresponding to the NSNS sector alone, and for the RR sector.

  7. Double parton scatterings at the CERN LHC

    CERN Document Server

    Del Fabbro, R


    Double parton collisions give important effects at the LHC and not only in the QCD sector. Given the relatively low threshold and the consequent large rate of production of bb pairs, one expects a large background of double parton collisions to the Higgs boson production and decay via the bbW channel, which is one of the most promising discovery channels at the LHC, if the Higgs mass is below the W/sup + /W/sup -/ threshold. (15 refs).

  8. Oat Doubled Haploids Following Maize Pollination. (United States)

    Davies, Philip A; Sidhu, Parminder K


    Doubled haploids (DHs) are an important tool for the accelerated production of new crop varieties. In oat, DHs were first produced by pollinating oat florets with maize pollen. The resultant embryos spontaneously eliminate the maize chromosomes leaving a haploid complement of oat chromosomes. These embryos can be cultured in vitro using the "embryo rescue" technique to produce haploid plants whose chromosome number can be doubled with colchicine to produce homozygous DH oat plants.

  9. Double Marginalisation Effect Within Logistics Chain


    Drago Pupavac


    Double marginalization occurs in vertical industries when both the upstream and downstream firms have monopoly power. Each firm reduces output from the competitive level to the monopoly level,creating two deadweight losses. This market myopia creates a "vertical externality" that vertical integration would internalize. In order to prove the hypothesis about building strategic partnership and collaboration as a way to remove the effect of double marginalization we have been focused on the rese...

  10. Nanofabrication of 10-nm T-shaped gates using a double patterning process with electron beam lithography and dry etch (United States)

    Shao, Jinhai; Deng, Jianan; Lu, W.; Chen, Yifang


    A process to fabricate T-shaped gates with the footprint scaling down to 10 nm using a double patterning procedure is reported. One of the keys in this process is to separate the definition of the footprint from that for the gate-head so that the proximity effect originated from electron forward scattering in the resist is significantly minimized, enabling us to achieve as narrow as 10-nm foot width. Furthermore, in contrast to the reported technique for 10-nm T-shaped profile in resist, this process utilizes a metallic film with a nanoslit as an etch mask to form a well-defined 10-nm-wide foot in a SiNx layer by reactive ion etch. Such a double patterning process has demonstrated enhanced reliability. The detailed process is comprehensively described, and its advantages and limitations are discussed. Nanofabrication of InP-based high-electron-mobility transistors using the developed process for 10- to 20-nm T-shaped gates is currently under the way.

  11. [Bleeding in digestive tract caused by jejunal angiodysplasia: complementary value of capsule endoscopy and double-balloon enteroscopy]. (United States)

    Vásquez, Jorge; Alva, Edgar; Frisancho, Oscar; Yoza, Max; Zumaeta, Eduardo; Watanabe, José; Palomino, Américo


    We report the case of a 35-year-old male patient, with a history of six months of pallor and dyspnea associated with severe iron deficiency anemia and positive fecal occult blood tests. Endoscopy of the lower and upper gastrointestinal tract, and a small bowel follow-through were performed, but did not reveal the origin of the bledding. Later, a capsule endoscopy study were performed and detected an elevated area - not well defined - with active bleeding in the jejunal portion of the small bowel, for that reason we decided to complement the study with a double balloon enteroscopy, that allowed us to see more clearly the jejunal lesion: an elevated and ulcerated lesion; the area was marked with India ink to guide the surgeon. In the surgical intervention a resection of the involved jejunal segment was performed; the study of pathological anatomy established the diagnosis of jejunal angiodysplasia. We present this case of obscure gastrointestinal bleeding to emphasize the diagnostic utility of capsule endoscopy and double balloon enteroscopy.


    Directory of Open Access Journals (Sweden)

    Geoff Pollard


    Full Text Available In this paper a family of scoring systems for tennis doubles for testing the hypothesis that pair A is better than pair B versus the alternative hypothesis that pair B is better than A, is established. This family or benchmark of scoring systems can be used as a benchmark against which the efficiency of any doubles scoring system can be assessed. Thus, the formula for the efficiency of any doubles scoring system is derived. As in tennis singles, one scoring system based on the play-the-loser structure is shown to be more efficient than the benchmark systems. An expression for the relative efficiency of two doubles scoring systems is derived. Thus, the relative efficiency of the various scoring systems presently used in doubles can be assessed. The methods of this paper can be extended to a match between two teams of 2, 4, 8, …doubles pairs, so that it is possible to establish a measure for the relative efficiency of the various systems used for tennis contests between teams of players.

  13. Re-naming D Double Prime (United States)

    Chao, Benjamin F.


    "Knowledge about the dynamics of the D double prime region is a key to unlock some fundamental mysteries of the Earth heat engine which governs a wide range of global geophysical processes from tectonics to geodynamo." This benign sentence makes complete sense to many geophysicists. But for many others, it makes sense all except the odd nomenclature "D double prime". One knows about the crust, upper and lower mantle, outer and inner core, but where is the D double prime region? What meaning does it try to convey? Where is D prime region, or D, or A, B, C regions for that matter, and are there higher-order primes? How does such an odd name come about anyway? D double prime, or more "simply" D", is a generic designation given to the thin shell, about 200 km thick, of the lowermost mantle just above the core-mantle boundary inside the Earth. Incidentally, whether D" is "simpler" than "D double prime" depends on whether you are pronouncing it or writing/typing it; and D" can be confusing to readers in distinguishing quotation marks (such as in the above sentences) and second derivatives, and to word processors in spelling check and indexing.

  14. Doubled strings, negative strings and null waves

    Energy Technology Data Exchange (ETDEWEB)

    Blair, Chris D.A. [Theoretische Natuurkunde, Vrije Universiteit Brussel, and the International Solvay Institutes,Pleinlaan 2, B-1050 Brussels (Belgium)


    We revisit the fundamental string (F1) solution in the doubled formalism. We show that the wave-like solution of double field theory (DFT) corresponding to the F1/pp-wave duality pair is more properly a solution of the DFT action coupled to a doubled sigma model action. The doubled string configuration which sources the pp-wave can be thought of as static gauge with the string oriented in a dual direction. We also discuss the DFT solution corresponding to a vibrating string, carrying both winding and momentum. We further show that the solution dual to the F1 in both time and space can be viewed as a “negative string” solution. Negative branes are closely connected to certain exotic string theories which involve unusual signatures for both spacetime and brane worldvolumes. In order to better understand this from the doubled point of view, we construct a variant of DFT suitable for describing theories in which the fundamental string has a Euclidean worldsheet, for which T-dualities appear to change the spacetime signature.

  15. Observing and Measuring Visual Double Stars

    CERN Document Server


    In these days of high-precision astrometric satellites, tremendous contributions to the science of astrometry are being made by amateur astronomers around the globe. This second edition of Observing and Measuring Visual Double Stars contains a significant amount of completely new material inspired by the work done by observers - particularly in the USA - since the first edition was published. Fifteen skilled and experienced astronomers have contributed chapters on their own specialization in the various fields. These include how to use the Internet to carry out precise astronomical measurement, an excellent guide to sketching double stars, and information on how to image double stars of unequal brightness. This new edition is the definitive book for those who are serious about this fascinating aspect of astronomy! Author Bob Argyle has been observing visual double stars for more than 40 years, some with the help of the world's biggest refractors, and has been director of the Webb Society Double Star Se...

  16. ITER PF6 double pancakes winding line

    Energy Technology Data Exchange (ETDEWEB)

    Du, Shuangsong [Institute of Plasma Physics, Chinese Academy of Science, Hefei (China); University of Science and Technology of China, Hefei (China); Wen, Wei, E-mail: [Institute of Plasma Physics, Chinese Academy of Science, Hefei (China); Chen, Jin; Wu, Weiyue; Song, Yuntao; Shen, Guang [Institute of Plasma Physics, Chinese Academy of Science, Hefei (China)


    Highlights: • ITER PF6 double pancakes “two-in-hand” winding line layout and main parameters were introduced, main winding sequences were also included. • Main features of each winding unit include de-spooling unit, straightening unit, sandblasting and cleaning unit, bending unit, turn insulation wrapping head, rotary table and automatic control system were depicted. • PF6 double pancake winding line was commissioned with PF5 empty jacket conductor after the installation and testing of each unit, ±0.5 mm turn positioning and ±2 turn to turn deviations were achieved. - Abstract: The Poloidal Field (PF) coils are one of the main sub-systems of the ITER magnets. The PF6 coil is being manufactured by the Institute of Plasma Physics, Chinese Academy of Sciences (ASIPP) as per the Poloidal Field coils cooperation agreement signed between ASIPP and Fusion for Energy (F4E).The ITER PF6 winding pack is composed by stacking of 9 double pancakes. Each double pancake is wound with a “two-in-hand” configuration. This paper describes the ITER PF6 double pancakes winding line, including layout and main parameters of the winding line, features of main units and the commissioning trial with PF5 empty jacket conductor.

  17. Synthesis of layered double hydroxides from eggshells

    Energy Technology Data Exchange (ETDEWEB)

    Li Songnan [Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, 150001 (China); Wang Fangyong [College of Engineering and Technology, Northeast Forestry University, 150001 (China); Jing Xiaoyan [Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, 150001 (China); Wang Jun, E-mail: [Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, 150001 (China); Saba, Jamil; Liu Qi; Ge Lan; Song Dalei; Zhang Milin [Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, 150001 (China)


    Graphical abstract: This is the XRD pattern and TEM image of 4Ca-Al layered double hydroxide, which is obtained from eggshells. It can be seen that the sample is of layered double hydroxide and shows the plate-like agglomerations with an average size of 20-100 nm. Highlights: Black-Right-Pointing-Pointer We synthesize layered double hydroxides from eggshells. Black-Right-Pointing-Pointer Eggshells are the mainly material in this method. Black-Right-Pointing-Pointer The additional alkaline solution is not required. - Abstract: Ca-Al and Ca-Fe layered double hydroxides (LDHs) were successfully synthesized from chicken eggshells by an ultrasonic wave assistant method. The products were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and Fourier transform infrared spectroscopy (FT-IR) techniques. XRD and TEM analyses showed that the 4Ca-Al LDHs were of high purity but other samples were not. The present study provides a simple, efficient and environmental friendly method to obtain LDHs from biowaste eggshells, in which additional alkaline solution is not required for synthesis. Moreover, eggshells provide all the requisite bivalent metal ions, which are needed to form layered double hydroxides.

  18. Double Engine for a Nebula (United States)


    ESO has just released a stunning new image of a field of stars towards the constellation of Carina (the Keel). This striking view is ablaze with a flurry of stars of all colours and brightnesses, some of which are seen against a backdrop of clouds of dust and gas. One unusual star in the middle, HD 87643, has been extensively studied with several ESO telescopes, including the Very Large Telescope Interferometer (VLTI). Surrounded by a complex, extended nebula that is the result of previous violent ejections, the star has been shown to have a companion. Interactions in this double system, surrounded by a dusty disc, may be the engine fuelling the star's remarkable nebula. The new image, showing a very rich field of stars towards the Carina arm of the Milky Way, is centred on the star HD 87643, a member of the exotic class of B[e] stars [1]. It is part of a set of observations that provide astronomers with the best ever picture of a B[e] star. The image was obtained with the Wide Field Imager (WFI) attached to the MPG/ESO 2.2-metre telescope at the 2400-metre-high La Silla Observatory in Chile. The image shows beautifully the extended nebula of gas and dust that reflects the light from the star. The central star's wind appears to have shaped the nebula, leaving bright, ragged tendrils of gas and dust. A careful investigation of these features seems to indicate that there are regular ejections of matter from the star every 15 to 50 years. A team of astronomers, led by Florentin Millour, has studied the star HD 87643 in great detail, using several of ESO's telescopes. Apart from the WFI, the team also used ESO's Very Large Telescope (VLT) at Paranal. At the VLT, the astronomers used the NACO adaptive optics instrument, allowing them to obtain an image of the star free from the blurring effect of the atmosphere. To probe the object further, the team then obtained an image with the Very Large Telescope Interferometer (VLTI). The sheer range of this set of observations

  19. High power double-scale pulses from a gain-guided double-clad fiber laser (United States)

    Zhang, Haitao; Gao, Gan; Li, Qinghua; Gong, Mali


    Generation of high power double-scale pulses from a gain-guided double-clad fiber laser is experimentally demonstrated. By employing the Yb-doped 10/130 double-clad fiber as the gain medium, the laser realizes an output power of 5.1 W and pulse energy of 0.175 µJ at repetition rate of 29.14 MHz. To the best of our knowledge, this average output power is the highest among the reported double-scale pulse oscillators. The autocorrelation trace of pulses contains the short (98 fs) and long (29.5 ps) components, and the spectral bandwidth of the pulse is 27.3 nm. Such double-scale pulses are well suited for seeding the high power MOPA (master oscillator power amplifier) systems, nonlinear frequency conversion and optical coherence tomography.

  20. Two-step rating-based 'double-faced applicability' test for sensory analysis of spread products as an alternative to descriptive analysis with trained panel. (United States)

    Kim, In-Ah; den-Hollander, Elyn; Lee, Hye-Seong


    Descriptive analysis with a trained sensory panel has thus far been the most well defined methodology to characterize various products. However, in practical terms, intensive training in descriptive analysis has been recognized as a serious defect. To overcome this limitation, various novel rapid sensory profiling methodologies have been suggested in the literature. Among these, attribute-based methodologies such as check-all-that-apply (CATA) questions showed results comparable to those of conventional sensory descriptive analysis. Kim, Hopkinson, van Hout, and Lee (2017a, 2017b) have proposed a novel attribute-based methodology termed the two-step rating-based 'double-faced applicability' test with a novel output measure of applicability magnitude (d' A ) for measuring consumers' product usage experience throughout various product usage stages. In this paper, the potential of the two-step rating-based 'double-faced applicability' test with d' A was investigated as an alternative to conventional sensory descriptive analysis in terms of sensory characterization and product discrimination. Twelve commercial spread products were evaluated using both conventional sensory descriptive analysis with a trained sensory panel and two-step rating-based 'double-faced applicability' test with an untrained sensory panel. The results demonstrated that the 'double-faced applicability' test can be used to provide a direct measure of the applicability magnitude of sensory attributes of the samples tested in terms of d' A for sensory characterization of individual samples and multiple sample comparisons. This suggests that when the appropriate list of attributes to be used in the questionnaire is already available, the two-step rating-based 'double-faced applicability' test with d' A can be used as a more efficient alternative to conventional descriptive analysis, without requiring any intensive training process. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. Double Planet Meets Triple Star (United States)


    High-Resolution VLT Image of Pluto Event on July 20, 2002 A rare celestial phenomenon involving the distant planet Pluto has occurred twice within the past month. Seen from the Earth, this planet moved in front of two different stars on July 20 and August 21, respectively, providing observers at various observatories in South America and in the Pacific area with a long awaited and most welcome opportunity to learn more about the tenuous atmosphere of that cold planet. On the first date, a series of very sharp images of a small sky field with Pluto and the star was obtained with the NAOS-CONICA (NACO) adaptive optics (AO) camera mounted on the ESO VLT 8.2-m YEPUN telescope at the Paranal Observatory. With a diameter of about 2300 km, Pluto is about six times smaller than the Earth. Like our own planet, it possesses a relatively large moon, Charon , measuring 1200 km across and circling Pluto at a distance of about 19,600 km once every 6.4 days. In fact, because of the similarity of the two bodies, the Pluto-Charon system is often referred to as a double planet . At the current distance of nearly 4,500 million km from the Earth, Pluto's disk subtends a very small angle in the sky, 0.107 arcsec. It is therefore very seldom that Pluto - during its orbital motion - passes exactly in front of a comparatively bright star. Such events are known as "occultations" , and it is difficult to predict exactly when and where on the Earth's surface they are visible. Stellar occultations When Pluto moves in front of a star, it casts a "shadow" on the Earth's surface within which an observer cannot see the star, much like the Earth's Moon hides the Sun during a total solar eclipse. During the occultation event, Pluto's "shadow" also moves across the Earth's surface. The width of this shadow is equal to Pluto's diameter, i.e. about 2300 km. One such occultation event was observed in 1988, and two others were expected to occur in 2002, according to predictions published in 2000 by

  2. Double-layer ice from first principles (United States)

    Chen, Ji; Schusteritsch, Georg; Pickard, Chris J.; Salzmann, Christoph G.; Michaelides, Angelos


    The formation of monolayer and multilayer ice with a square lattice structure has recently been reported on the basis of transmission electron microscopy experiments, renewing interest in confined two-dimensional ice. Here we report a systematic density functional theory study of double-layer ice in nanoconfinement. A phase diagram as a function of confinement width and lateral pressure is presented. Included in the phase diagram are honeycomb hexagonal, square-tube, hexagonal-close-packed, and buckled-rhombic structures. However, contrary to experimental observations, square structures do not feature: our most stable double-layer square structure is predicted to be metastable. This study provides general insight into the phase transitions of double-layer confined ice and a fresh theoretical perspective on the stability of square ice in graphene nanocapillary experiments.

  3. Neutrinoless double beta decay from lattice QCD (United States)

    Nicholson, Amy; Cheng, Chia; Berkowitz, Evan; Rinaldi, Enrico; Walker-Loud, Andre; Vranas, Pavlos; Kurth, Thorsten; Clark, M. A.; Garron, Nicolas; Tiburzi, Brian; Monge-Camacho, Henry; Brantley, David; Joo, Balint; Callat Collaboration


    Lepton number-violating neutrinoless double beta decay is a natural consequence of Majorana neutrinos and many BSM theories, and, if observed, could potentially explain the observed matter/anti-matter asymmetry in the universe. Several experimental searches for these processes using nuclear sources are planned and/or underway worldwide, and understanding quantitatively how neutrinoless double beta decay would manifest in nuclear environments is key for interpreting any observed signals. While long-range, light neutrino exchange is the most common mechanism studied, short-range interactions involving heavy mediator exchange may also contribute. In this talk I will give an overview of the microscopic observables relevant for experimental searches for neutrinoless double beta decay which may be calculated directly from QCD using lattice methods, and present results for short-range matrix elements contributing to pion exchange diagrams between nucleons.

  4. Excitonic superfluid phase in double bilayer graphene (United States)

    Li, J. I. A.; Taniguchi, T.; Watanabe, K.; Hone, J.; Dean, C. R.


    A spatially indirect exciton is created when an electron and a hole, confined to separate layers of a double quantum well system, bind to form a composite boson. Such excitons are long-lived, and in the limit of strong interactions are predicted to undergo a Bose-Einstein condensate-like phase transition into a superfluid ground state. Here, we report evidence of an exciton condensate in the quantum Hall effect regime of double-layer structures of bilayer graphene. Interlayer correlation is identified by quantized Hall drag at matched layer densities, and the dissipationless nature of the phase is confirmed in the counterflow geometry. A selection rule for the condensate phase is observed involving both the orbital and valley indices of bilayer graphene. Our results establish double bilayer graphene as an ideal system for studying the rich phase diagram of strongly interacting bosonic particles in the solid state.

  5. Generalised kinematics for double field theory (United States)

    Freidel, Laurent; Rudolph, Felix J.; Svoboda, David


    We formulate a kinematical extension of Double Field Theory on a 2 d-dimensional para-Hermitian manifold (P,η, ω ) where the O( d, d) metric η is supplemented by an almost symplectic two-form ω. Together η and ω define an almost bi-Lagrangian structure K which provides a splitting of the tangent bundle TP=L\\oplus \\tilde{L} into two Lagrangian sub-spaces. In this paper a canonical connection and a corresponding generalised Lie derivative for the Leibniz algebroid on TP are constructed. We find integrability conditions under which the symmetry algebra closes for general η and ω, even if they are not flat and constant. This formalism thus provides a generalisation of the kinematical structure of Double Field Theory. We also show that this formalism allows one to reconcile and unify Double Field Theory with Generalised Geometry which is thoroughly discussed.

  6. Double Dirac Semimetals in Three Dimensions. (United States)

    Wieder, Benjamin J; Kim, Youngkuk; Rappe, A M; Kane, C L


    We study a class of Dirac semimetals that feature an eightfold-degenerate double Dirac point. We show that 7 of the 230 space groups can host such Dirac points and argue that they all generically display linear dispersion. We introduce an explicit tight-binding model for space groups 130 and 135. Space group 135 can host an intrinsic double Dirac semimetal with no additional states at the Fermi energy. This defines a symmetry-protected topological critical point, and we show that a uniaxial compressive strain applied in different directions leads to topologically distinct insulating phases. In addition, the double Dirac semimetal can accommodate topological line defects that bind helical modes. Connections are made to theories of strongly interacting filling-enforced semimetals, and potential materials realizations are discussed.

  7. Limiting effects in double EEX beamline (United States)

    Ha, G.; Power, J. G.; Conde, M.; Doran, D. S.; Gai, W.


    The double emittance exchange (EEX) beamline is suggested to overcome the large horizontal emittance and transverse jitter issues associated with the single EEX beamline while preserving its powerful phase-space manipulation capability. However, the double EEX beamline also has potential limitations due to coherent synchrotron radiation (CSR) and transverse jitter. The former limitation arises because double EEX uses twice as many bending magnets as single EEX which means stronger CSR effects degrading the beam quality. The latter limitation arises because a longitudinal jitter in front of the first EEX beamline is converted into a transverse jitter in the middle section (between the EEX beamlines) which can cause beam loss or beam degradation. In this paper, we numerically explore the effects of these two limitations on the emittance and beam transport.

  8. Innocuous Double Rounding of Basic Arithmetic Operations

    Directory of Open Access Journals (Sweden)

    Pierre Roux


    Full Text Available Double rounding occurs when a floating-point value is first rounded to an intermediate precision before being rounded to a final precision. The result of two such consecutive roundings can differ from the result obtained when directly rounding to the final precision. Double rounding practically happens, for instance, when implementing the IEEE754 binary32 format with an arithmetic unit performing operations only in the larger binary64 format, such as done in the PowerPC or x87 floating-point units. It belongs to the folklore in the floating-point arithmetic community that double rounding is innocuous for the basic arithmetic operations (addition, division, multiplication, and square root as soon as the final precision is about twice larger than the intermediate one. This paper adresses the formal proof of this fact considering underflow cases and its extension to radices other than two.

  9. Jonckheere Double Star Photometry - Part IV: Cetus (United States)

    Knapp, Wilfried


    If any double star discoverer is in urgent need of photometry then it is Jonckheere. There are over 3000 Jonckheere objects listed in the WDS catalog and a good part of them have magnitudes which are obviously far too bright. This report covers the Jonckheere objects in the constellation Cet. Only one image per object was taken as despite the risk of random effects even a single measurement is better than the currently usually given estimation although the J-objects in this southern constellation are better covered with observations as usual for Jonckheere doubles.

  10. Double-partition Quantum Cluster Algebras

    DEFF Research Database (Denmark)

    Jakobsen, Hans Plesner; Zhang, Hechun


    A family of quantum cluster algebras is introduced and studied. In general, these algebras are new, but sub-classes have been studied previously by other authors. The algebras are indexed by double parti- tions or double flag varieties. Equivalently, they are indexed by broken lines L. By grouping...... together neighboring mutations into quantum line mutations we can mutate from the cluster algebra of one broken line to another. Compatible pairs can be written down. The algebras are equal to their upper cluster algebras. The variables of the quantum seeds are given by elements of the dual canonical basis....

  11. Unique double recurrence of cerebral arteriovenous malformation. (United States)

    Nagm, Alhusain; Horiuchi, Tetsuyoshi; Ichinose, Shunsuke; Hongo, Kazuhiro


    Surgically treated patients with arteriovenous malformations (AVMs) are considered cured when the postoperative angiogram proves complete resection. However, despite no residual nidus or early draining vein on postoperative angiogram, rare instances of AVM recurrence have been reported in adults. In this paper, the authors present a case of a 24-year-old woman with asymptomatic double recurrence of her cerebral AVM after angiographically proven complete resection. To the authors' knowledge, this patient represents the first case with double de novo asymptomatic recurrence of Spetzler-Martin grade I AVM. Also, she represents the first case with unique AVM criteria in each recurrence.

  12. Simulation Results of Double Forward Converter

    Directory of Open Access Journals (Sweden)

    P. Vijaya KUMAR


    Full Text Available This work aims to find a better forward converter for DC to DC conversion.Simulation of double forward converter in SMPS system is discussed in this paper. Aforward converter with RCD snubber to synchronous rectifier and/or to current doubleris also discussed. The evolution of the forward converter is first reviewed in a tutorialfashion. Performance parameters are discussed including operating principle, voltageconversion ratio, efficiency, device stress, small-signal dynamics, noise and EMI. Itscircuit operation and its performance characteristics of the forward converter with RCDsnubber and double forward converter are described and the simulation results arepresented.

  13. Double conformal space-time algebra (United States)

    Easter, Robert Benjamin; Hitzer, Eckhard


    The Double Conformal Space-Time Algebra (DCSTA) is a high-dimensional 12D Geometric Algebra G 4,8that extends the concepts introduced with the Double Conformal / Darboux Cyclide Geometric Algebra (DCGA) G 8,2 with entities for Darboux cyclides (incl. parabolic and Dupin cyclides, general quadrics, and ring torus) in spacetime with a new boost operator. The base algebra in which spacetime geometry is modeled is the Space-Time Algebra (STA) G 1,3. Two Conformal Space-Time subalgebras (CSTA) G 2,4 provide spacetime entities for points, flats (incl. worldlines), and hyperbolics, and a complete set of versors for their spacetime transformations that includes rotation, translation, isotropic dilation, hyperbolic rotation (boost), planar reflection, and (pseudo)spherical inversion in rounds or hyperbolics. The DCSTA G 4,8 is a doubling product of two G 2,4 CSTA subalgebras that inherits doubled CSTA entities and versors from CSTA and adds new bivector entities for (pseudo)quadrics and Darboux (pseudo)cyclides in spacetime that are also transformed by the doubled versors. The "pseudo" surface entities are spacetime hyperbolics or other surface entities using the time axis as a pseudospatial dimension. The (pseudo)cyclides are the inversions of (pseudo)quadrics in rounds or hyperbolics. An operation for the directed non-uniform scaling (anisotropic dilation) of the bivector general quadric entities is defined using the boost operator and a spatial projection. DCSTA allows general quadric surfaces to be transformed in spacetime by the same complete set of doubled CSTA versor (i.e., DCSTA versor) operations that are also valid on the doubled CSTA point entity (i.e., DCSTA point) and the other doubled CSTA entities. The new DCSTA bivector entities are formed by extracting values from the DCSTA point entity using specifically defined inner product extraction operators. Quadric surface entities can be boosted into moving surfaces with constant velocities that display the length

  14. Double Harmonic Transmission (D.H.T.

    Directory of Open Access Journals (Sweden)

    Sava Ianici


    Full Text Available The paper presents the construction and functioning of a new type of harmonic drive named double harmonic transmission (D.H.T.. In the second part of this paper is presented the dynamic analysis of the double harmonic transmission, which is based on the results of the experimental researches on the D.H.T. This study of the stress status and the forces distribution is necessary for to determine the durability on the portant elements of the D.H.T.

  15. Jonckheere Double Star Photometry - Part VI: Auriga (United States)

    Knapp, Wilfried


    If any double star discoverer is in urgent need of photometry then it is Jonckheere. There are over 3000 Jonckheere objects listed in the WDS catalog and a good part of them has magnitudes which are obviously far too bright. This report covers the Jonckheere objects in the constellation Auriga. Only one image per object was taken as despite the risk of random effects even a single instance visual magnitude measurement is better than the currently usually given estimation although the J-objects in this constellation seem with some exceptions better covered with observations as usual for Jonckheere doubles.

  16. Jonckheere Double Star Photometry - Part V: Cancer (United States)

    Knapp, Wilfried


    If any double star discoverer is in urgent need of photometry then it is Jonckheere. There are over 3000 Jonckheere objects listed in the WDS catalog and a good part of them have magnitudes which are obviously far too bright. This report covers the Jonckheere objects in the constellation Cancer. Only one image per object was taken as despite the risk of random effects even a single measurement is better than the currently usually given estimation, although the J-objects in this constellation seem with some exceptions better covered with observations as usual for Jonckheere doubles.

  17. Probabilistic double guarantee kidnapping detection in SLAM. (United States)

    Tian, Yang; Ma, Shugen


    For determining whether kidnapping has happened and which type of kidnapping it is while a robot performs autonomous tasks in an unknown environment, a double guarantee kidnapping detection (DGKD) method has been proposed. The good performance of DGKD in a relative small environment is shown. However, a limitation of DGKD is found in a large-scale environment by our recent work. In order to increase the adaptability of DGKD in a large-scale environment, an improved method called probabilistic double guarantee kidnapping detection is proposed in this paper to combine probability of features' positions and the robot's posture. Simulation results demonstrate the validity and accuracy of the proposed method.

  18. Dynamically possible pattern speeds of double bars


    Maciejewski, Witold


    The method to study oscillating potentials of double bars, based on invariant loops, is introduced here in a new way, intended to be more intelligible. Using this method, I show how the orbital structure of a double-barred galaxy (nested bars) changes with the variation of nuclear bar's pattern speed. Not all pattern speeds are allowed when the inner bar rotates in the same direction as the outer bar. Below certain minimum pattern speed orbital support for the inner bar abruptly disappears, w...

  19. Facility Location with Double-peaked Preferences

    DEFF Research Database (Denmark)

    Filos-Ratsikas, Aris; Li, Minming; Zhang, Jie


    We study the problem of locating a single facility on a real line based on the reports of self-interested agents, when agents have double-peaked preferences, with the peaks being on opposite sides of their locations. We observe that double-peaked preferences capture real-life scenarios and thus...... complement the well-studied notion of single-peaked preferences. We mainly focus on the case where peaks are equidistant from the agents’ locations and discuss how our results extend to more general settings. We show that most of the results for single-peaked preferences do not directly apply to this setting...

  20. Double sequential defibrillation for refractory ventricular fibrillation. (United States)

    El Tawil, Chady; Mrad, Sandra; Khishfe, Basem F


    A 54-year-old suffered from an out-of-hospital cardiac arrest. Compressions were started within minutes and the patient was in refractory ventricular fibrillation despite multiple asynchronized shocks and maximal doses of antiarrhythmic agents. Double sequential defibrillation was attempted with successful Return Of Spontaneous Circulation (ROSC) after a total of 61min of cardiac arrest. The patient was discharged home neurologically intact. Double sequential defibrillation could be a simple effective approach to patients with refractory ventricular fibrillation. Copyright © 2017 Elsevier Inc. All rights reserved.

  1. Double parton scattering in the ultraviolet. Addressing the double counting problem

    Energy Technology Data Exchange (ETDEWEB)

    Diehl, Markus [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Gaunt, Jonathan R. [Nikhef Theory Group, Amsterdam (Netherlands); Amsterdam VU Univ. (Netherlands)


    An important question in the theory of double parton scattering is how to incorporate the possibility of the parton pairs being generated perturbatively via 1→ 2splitting into the theory, whilst avoiding double counting with single parton scattering loop corrections. Here, we describe a consistent approach for solving this problem, which retains the notion of double parton distributions (DPDs) for individual hadrons. Further, we discuss the construction of appropriate model DPDs in our framework, and the use of these to compute the DPS part, presenting DPS 'luminosities' from our model DPDs for a few sample cases.

  2. Material capture by double lunar gravity assist (United States)

    Ross, D. J.


    The equations yielding the performance of a single lunar flyby in removing incoming hyperbolic excess velocity to capture payloads on interplanetary trajectories are briefly derived. The impossibility of using a single lunar flyby to capture a body entering the earth-moon system with a hyperbolic velocity in excess of about 1.9 km/s is discussed, and a method of using a double flyby of the moon to significantly improve this performance is developed. The equations for achieving a double lunar flyby are derived by solving the orbital equations and Lambert's problem both for the incoming trajectory in the plane of the moon's orbit and for arbitrary declination. For the in-plane case it is shown that the maximum removable hyperbolic excess velocity is 2.2687 km/s. For the inclined case, it is shown that the use of a double lunar flyby allows capture for declinations in excess of 54 degrees, and that for declinations less than 38 degrees the double lunar flyby offers better performance than the single lunar flyby.

  3. On double Hurwitz numbers with completed cycles

    NARCIS (Netherlands)

    Shadrin, S.; Spitz, L.; Zvonkine, D.


    In this paper, we collect a number of facts about double Hurwitz numbers, where the simple branch points are replaced by their more general analogues: completed (r + 1)-cycles. In particular, we give a geometric interpretation of these generalized Hurwitz numbers and derive a cut-and-join operator

  4. The Modular Construction of DNA Double Helix

    Indian Academy of Sciences (India)

    host; its usual right-handed helix profile can change all the way to the left-handed double one, the entire spectrum with expen- diture of minimum energy. Its major groove can play host to countless guests leading to recognition and the resulting bio- logical functions; its minor groove can receive antibiotics initi-.

  5. Double Pomeron Exchange: the early years

    Energy Technology Data Exchange (ETDEWEB)

    Albrow, Michael G. [Fermilab


    I review the early experimental searches for double pomeron exchange, the first observations at the CERN Intersecting Storage Rings (ISR) and further studies at the SPS and Tevatron (fixed target). I only have space for a superficial coverage of some highlights, and will not cover later colliders with √s > GeV.

  6. Oxygen isotope fractionation in double carbonates. (United States)

    Zheng, Yong-Fei; Böttcher, Michael E


    Oxygen isotope fractionations in double carbonates of different crystal structures were calculated by the increment method. Synthesis experiments were performed at 60 °C and 100 °C to determine oxygen and carbon isotope fractionations involving PbMg[CO3]2. The calculations suggest that the double carbonates of calcite structure are systematically enriched in (18)O relative to those of aragonite and mixture structures. Internally consistent oxygen isotope fractionation factors are obtained for these minerals with respect to quartz, calcite and water at a temperature range of 0-1200 °C. The calculated fractionation factors for double carbonate-water systems are generally consistent with the data available from laboratory experiments. The experimentally determined fractionation factors for PbMg[CO3]2, BaMg[CO3]2 and CaMg[CO3]2 against H2O not only fall between fractionation factors involving pure carbonate end-members but are also close to the calculated fractionation factors. In contrast, experimentally determined carbon isotope fractionation factors between PbMg[CO3]2 and CO2 are much closer to theoretical predictions for the cerussite-CO2 system than for the magnesite-CO2 system, similar to the fractionation behavior for BaMg[CO3]2. Therefore, the combined theoretical and experimental results provide insights into the effects of crystal structure and exchange kinetics on oxygen isotope partitioning in double carbonates.

  7. Double-Stranded Peptide Nucleic Acids

    DEFF Research Database (Denmark)


    A novel class of compounds, known as peptide nucleic acids, form double-stranded structures with one another and with ssDNA. The peptide nucleic acids generally comprise ligands such as naturally occurring DNA bases attached to a peptide backbone through a suitable linker....

  8. Double tracks test site characterization report

    Energy Technology Data Exchange (ETDEWEB)



    This report presents the results of site characterization activities performed at the Double Tracks Test Site, located on Range 71 North, of the Nellis Air Force Range (NAFR) in southern Nevada. Site characterization activities included reviewing historical data from the Double Tracks experiment, previous site investigation efforts, and recent site characterization data. The most recent site characterization activities were conducted in support of an interim corrective action to remediate the Double Tracks Test Site to an acceptable risk to human health and the environment. Site characterization was performed using a phased approach. First, previously collected data and historical records sere compiled and reviewed. Generalized scopes of work were then prepared to fill known data gaps. Field activities were conducted and the collected data were then reviewed to determine whether data gaps were filled and whether other areas needed to be investigated. Additional field efforts were then conducted, as required, to adequately characterize the site. Characterization of the Double Tracks Test Site was conducted in accordance with the US Department of Energy`s (DOE) Streamlined Approach for Environmental Restoration (SAFER).

  9. Constraining double-parton correlations and interferences

    NARCIS (Netherlands)

    Kasemets, T.; Mulders, P.J.G.


    Double-parton scattering (DPS) has become very relevant as a background to interesting analyses performed by the experiments at the LHC. It encodes knowledge of correlations between the proton constituents not accessible in single-parton scattering. Within perturbative QCD DPS is described in terms

  10. New orbital elements for 5 double stars

    Directory of Open Access Journals (Sweden)

    Olević D.


    Full Text Available In this paper are presented recalculated elliptical and Thiel-Innes orbitatal elements for the following double stars: WDS05255-0033, WDS12272+2701, WDS 13336+2944 and WDS 21031+0132 (two versions. The elements of the pair WDS 06074+2640 = McA 25 are calculated for the first time.

  11. Double-compression method for biomedical images (United States)

    Antonenko, Yevhenii A.; Mustetsov, Timofey N.; Hamdi, Rami R.; Małecka-Massalska, Teresa; Orshubekov, Nurbek; DzierŻak, RóŻa; Uvaysova, Svetlana


    This paper describes a double compression method (DCM) of biomedical images. A comparison of image compression factors in size JPEG, PNG and developed DCM was carried out. The main purpose of the DCM - compression of medical images while maintaining the key points that carry diagnostic information. To estimate the minimum compression factor an analysis of the coding of random noise image is presented.

  12. Single and Double Superconducting Coplanar Waveguide Resonators (United States)

    Zhao, Na; Liu, Jian-She; Li, Hao; Li, Tie-Fu; Chen, Wei


    Transmission characteristics of single and double coplanar waveguide (CPW) resonators are simulated. The crosstalk of two CPW resonators located on the same chip is observed in simulation as well as in low temperature measurement results. The crosstalk behaves as exponential attenuation versus the distance between two resonators.

  13. [Euthanasia and the doctrine of double effect]. (United States)

    Klein, Martin


    Direct active euthanasia is prohibited in most countries while passive and indirect is not. However, many arguments against the legalization of voluntary active euthanasia are flawed. Ethical differences between active and passive or indirect euthanasia are difficult to maintain especially when the passivity of the actor causes death. The crucial point is not activity or passivity but respect for the autonomy of individual human beings. In particular there appears to be little ethical difference between active and indirect euthanasia. Indirect euthanasia has often been justified by the principle of double effect, which traces back to Thomas Aquinas. But resorting to this rule contains a logical fallacy. The principle of double effect does not allow foreseen and unwanted adverse effects of an action to occur when they are avoidable. In terminal sedation, an example for indirect euthanasia, hypoxemia and dehydration can easily be prevented by respirator therapy and fluid administration. Therefore the rule of double effect is not applicable. Indirect and direct active euthanasia cannot be ethically distinguished by resorting to the principle of double effect.

  14. The Double Bind: The next Generation (United States)

    Malcom, Lindsey E.; Malcom, Shirley M.


    In this foreword, Shirley Malcom and Lindsey Malcom speak to the history and current status of women of color in science, technology, engineering, and mathematics (STEM) fields. As the author of the seminal report "The Double Bind: The Price of Being a Minority Woman in Science", Shirley Malcom is uniquely poised to give us an insightful…

  15. [Double aortic arch: prenatal case report]. (United States)

    Budziszewska, Patrycja; Kuka, Dorota; Sodowski, Marcin; Sodowski, Krzysztof; Jeanty, Philippe; Skrzypulec, Violetta


    We have presented a case of prenatal double aortic arch, diagnosed by ultrasound, to demonstrate the importance of 3-vessel view by detecting aortic arch abnormalities. Double aortic arch is one the most common types of the vascular ring. The suspicion of a double aortic arch is raised by detecting the U-sign which is formed by the combination of both aortic arches and the left ductus arteriosus. In the 3-vessel view the ascending aorta and aortic arch are pointing to the right, whereas the left arch points to the left, and the trachea is seen between. The 4-chamber view appears normal, but the descending aorta is deviated medially. Literature review revealed an association between double aortic arch and congenital heart diseases in approximately 20% of cases; most often tetralogy of Fallot, transposition of great vessels, ventricular septal defects. Rarely there can be atresia of the segment of the aortic arch, which can be difficult to differentiate from other aortic arch anomalies associated with chromosomal abnormalities such as microdeletion of chromosome 22q11.

  16. An Optimal Double Inequality for Means

    Directory of Open Access Journals (Sweden)

    Qian Wei-Mao


    Full Text Available For , the generalized logarithmic mean , arithmetic mean and geometric mean of two positive numbers and are defined by , ; , , , ; , , ; , , ; and , respectively. In this paper, we give an answer to the open problem: for , what are the greatest value and the least value , such that the double inequality holds for all ?

  17. Double orifice mitral valve; a coincidental finding

    NARCIS (Netherlands)

    Westendorp, Iris C. D.; de Bruin-Bon, H. A. C. M.; Hrudova, Jana


    A double orifice mitral valve (DOMV) represents a rare congenital malformation characterised by two valve orifices with two separate subvalvular apparatus. This case demonstrates the necessity of careful imaging of the mitral valve apparatus, not only in patients with atrioventricular septal

  18. Statistical Convergence of Double Sequences of Order

    Directory of Open Access Journals (Sweden)

    R. Çolak


    Full Text Available We intend to make a new approach and introduce the concepts of statistical convergence of order and strongly -Cesàro summability of order for double sequences of complex or real numbers. Also, some relations between the statistical convergence of order and strong -Cesàro summability of order are given.

  19. The College Double Major and Subsequent Earnings (United States)

    Hemelt, Steven W.


    In this study I examine the relationship between graduating from college with two majors rather than one and labor market earnings using the 2003 National Survey of College Graduates. Because institutions are heterogeneous both in terms of overall quality and in the availability of opportunities to double major, I attempt to control for such…

  20. Salinity transfer in bounded double diffusive convection

    NARCIS (Netherlands)

    Yang, Yantao; van der Poel, Erwin; Ostilla Monico, Rodolfo; Sun, Chao; Verzicco, Roberto; Grossmann, Siegfried; Lohse, Detlef


    The double diffusive convection between two parallel plates is numerically studied for a series of parameters. The flow is driven by the salinity difference and stabilised by the thermal field. Our simulations are directly compared with experiments by Hage & Tilgner (Phys. Fluids, vol. 22, 2010,

  1. State dynamics of a double sandbar system

    NARCIS (Netherlands)

    Price, T.D.; Ruessink, B.G.


    A 9.3-year dataset of low-tide time-exposure images from Surfers Paradise, Northern Gold Coast, Australia was used to characterise the state dynamics of a double sandbar system. The morphology of the nearshore sandbars was described by means of the sequential bar state classification scheme of

  2. The invertible double of elliptic operators

    DEFF Research Database (Denmark)

    Booss-Bavnbek, Bernhelm; Lesch, Matthias; Zhu, Chaofeng

    We construct a canonical invertible double for general first order elliptic differential operators over smooth compact manifolds with boundary and derive a natural formula for the Calderon projector which yields a generalization of the famous Cobordism Theorem. Assuming symmetric principal symbol...

  3. Double-balloon endoscopy: Who needs it?

    DEFF Research Database (Denmark)

    Hendel, J.W.; Vilmann, P.; Jensen, T.


    Objective. Double-balloon endoscopy (DBE) made the small bowel accessible to inspection and therapy in its entirety. However, DBE is a time-consuming procedure that requires a highly skilled endoscopist, several nurses and - more often than not - anesthesiological support. This makes the selection...

  4. Under the Gaze of Double Critique

    DEFF Research Database (Denmark)

    Sabih, Joshua


    of the theory of double critique: decolonisation, desacralisation and the orphan book are operative in Ḫaṭībī´s analysis of Orientalism, identity, and the issue of origin. As a professional outsider, Ḫaṭībī follows conceptually and methodologically the rules of the epistemological critique in an enunciation...

  5. A Morphism Double Category and Monoidal Structure

    Directory of Open Access Journals (Sweden)

    Saikat Chatterjee


    Full Text Available We provide a recipe for “fattening” a category that leads to the construction of a double category. Motivated by an example where the underlying category has vector spaces as objects, we show how a monoidal category leads to a law of composition, satisfying certain coherence properties, on the object set of the fattened category.

  6. The Discovery of the Double Helix

    CERN Multimedia

    CERN. Geneva


    Professor James D. Watson has kindly agreed to make a presentation on the 1953 finding of the Double Helix at the Cavendish Laboratory by Francis Crick and himself. Being one of the greatest scientific discoveries in human history, little else needs to be added.

  7. Double-outlet right ventricle revisited. (United States)

    Ebadi, Ameneh; Spicer, Diane E; Backer, Carl L; Fricker, F Jay; Anderson, Robert H


    Double-outlet right ventricle is a form of ventriculoarterial connection. The definition formulated by the International Society for Nomenclature of Paediatric and Congenital Heart Disease is based on hearts with both arterial trunks supported in their greater part by a morphologically right ventricle. Bilateral infundibula and ventricular septal defects are highly debated criteria. This study examines the anatomic controversies surrounding double-outlet right ventricle. We show that hearts with double-outlet right ventricle can have atrioventricular-to-arterial valvular continuity. We emphasize the difference between the interventricular communication and the zone of deficient ventricular septation. The hearts examined were from the University of Florida in Gainesville; Johns Hopkins All Children's Hospital, St Petersburg, Fla; and Lurie Children's Hospital, Chicago, Ill. Each specimen had at least 75% of both arterial roots supported by the morphologically right ventricle, with a total of 100 hearts examined. The morphologic method was used to assess anatomic features, including arterial-atrioventricular valvular continuity, subarterial infundibular musculature, and the location of the hole between the ventricles. Most hearts had fibrous continuity between one of the arterial valves and an atrioventricular valve, with bilateral infundibula in 23%, and intact ventricular septum in 5%. Bilateral infundibula are not a defining feature of double-outlet right ventricle, representing only 23% of the specimens in our sample. The interventricular communication can have a posteroinferior muscular rim or extend to become perimembranous (58%). Double-outlet right ventricle can exist with an intact ventricular septum. Copyright © 2017 The American Association for Thoracic Surgery. All rights reserved.

  8. Delivery of double singleton pregnancies in a woman with a double uterus, double cervix, and complete septate vagina

    Directory of Open Access Journals (Sweden)

    Ming-Jie Yang


    Full Text Available Uterine anomalies involving a double uterus, double cervix, also known as didelphys uterus, and complete septate vagina are rarely seen and have an associated fertility problem. However, artificial reproductive technology with embryo transfers can help solve this fertility challenge. Conception in the uterus in just one side is commonly seen for embryos, which are always transferred through the usually used (dilated vagina. We here present a patient with the above uterine anomaly who conceived with the aid of in vitro fertilization and embryo transfer to both uterine cavities under general anesthesia, which resulted in successful double singleton pregnancies with one fetus in each uterus. With intensive prenatal care, the pregnancy course for each fetus was rather uneventful. Although both fetuses were in cephalic presentation, cesarean section was performed at the 39th week of gestation with good outcomes in order to preclude anticipated difficulties if the baby had been delivered through the rarely dilated vagina. However, order of birth between the two fetuses was a crucial decision during the operation.

  9. 46 CFR 173.058 - Double bottom requirements. (United States)


    ... PERTAINING TO VESSEL USE School Ships § 173.058 Double bottom requirements. Each new sailing school vessel... service must comply with the double bottom requirements in §§ 171.105 through 171.109, inclusive, of this...

  10. Heuristic Solution Approaches to the Double TSP with Multiple Stacks

    DEFF Research Database (Denmark)

    Petersen, Hanne Løhmann


    This paper introduces the Double Travelling Salesman Problem with Multiple Stacks and presents a three different metaheuristic approaches to its solution. The Double Travelling Salesman Problem with Multiple Stacks is concerned with finding the shortest route performing pickups and deliveries...

  11. Heuristic Solution Approaches to the Double TSP with Multiple Stacks

    DEFF Research Database (Denmark)

    Petersen, Hanne Løhmann

    This paper introduces the Double Travelling Salesman Problem with Multiple Stacks and presents a three different metaheuristic approaches to its solution. The Double Travelling Salesman Problem with Multiple Stacks is concerned with finding the shortest route performing pickups and deliveries...

  12. Double folding model analysis of elastic scattering of halo nucleus ...

    Indian Academy of Sciences (India)


    Coulomb barrier energy have been performed using a potential obtained from the double folding model and are compared with the experiment. In the framework of the double folding model, the nuclear matter densities of 9,10 ...

  13. Micrometer and CCD measurements of double stars (Series 51

    Directory of Open Access Journals (Sweden)

    Popović G.M.


    Full Text Available 36 micrometric measurements of 20 double or multiple systems carried out with the Zeiss 65/1055 cm Refractor of Belgrade Observatory are communicated. Also 35 CCD measurements of 15 double or multiple systems are included.

  14. Boltzmann equation with double-well potentials (United States)

    Chiacchiera, Silvia; Macrı, Tommaso; Trombettoni, Andrea


    We study the dynamics of an interacting classical gas trapped in a double-well potential at finite temperature. Two model potentials are considered: a cubic box with a square barrier in the middle, and a harmonic trap with a Gaussian barrier along one direction. The study is performed using the Boltzmann equation, solved numerically via the test-particle method. We introduce and discuss a simple analytical model that allows one to provide estimates of the relaxation time, which are compared with numerical results. Finally, we use our findings to make numerical and analytical predictions for the case of a fermionic mixture in the normal-fluid phase in a realistic double-well potential relevant for experiments with cold atoms.

  15. Phonon tunneling through a double barrier system

    Energy Technology Data Exchange (ETDEWEB)

    Villegas, Diosdado [Departamento de Física, Universidad Central “Marta Abreu” de Las Villas, CP 54830, Santa Clara, Villa Clara (Cuba); Instituto de Física, Universidad Autónoma de Puebla, 18 Sur y San Claudio, Edif. 110A, Ciudad Universitaria, 72570 Puebla (Mexico); León-Pérez, Fernando de [Centro Universitario de la Defensa de Zaragoza, Ctra. de Huesca s/n, E-50090 Zaragoza (Spain); Pérez-Álvarez, R. [Universidad Autónoma del Estado de Morelos, Av. Universidad 1001, CP 62209 Cuernavaca (Mexico); Arriaga, J., E-mail: [Instituto de Física, Universidad Autónoma de Puebla, 18 Sur y San Claudio, Edif. 110A, Ciudad Universitaria, 72570 Puebla (Mexico)


    The tunneling of optical and acoustic phonons at normal incidence on a double-barrier is studied in this paper. Transmission coefficients and resonance conditions are derived theoretically under the assumption that the long-wavelength approximation is valid. It is shown that the behavior of the transmission coefficients for the symmetric double barrier has a Lorentzian form close to resonant frequencies and that Breit–Wigner's formula have a general validity in one-dimensional phonon tunneling. Authors also study the so-called generalized Hartman effect in the tunneling of long-wavelength phonons and show that this effect is a numerical artifact resulting from taking the opaque limit before exploring the variation with a finite barrier width. This study could be useful for the design of acoustic devices.

  16. The DNA double helix fifty years on. (United States)

    Macgregor, Robert B; Poon, Gregory M K


    This year marks the 50th anniversary of the proposal of a double helical structure for DNA by James Watson and Francis Crick. The place of this proposal in the history and development of molecular biology is discussed. Several other discoveries that occurred in the middle of the twentieth century were perhaps equally important to our understanding of cellular processes; however, none of these captured the attention and imagination of the public to the same extent as the double helix. The existence of multiple forms of DNA and the uses of DNA in biological technologies is presented. DNA is also finding increasing use as a material due to its rather unusual structural and physical characteristics as well as its ready availability.

  17. Quantum capacitance of double-layer graphene (United States)

    Parhizgar, Fariborz; Qaiumzadeh, Alireza; Asgari, Reza


    We study the ground-state properties of a double-layer graphene system with the Coulomb interlayer electron-electron interaction modeled within the random-phase approximation. We first obtain an expression of the quantum capacitance of a two-layer system. In addition, we calculate the many-body exchange-correlation energy and quantum capacitance of the hybrid double-layer graphene system at zero temperature. We show an enhancement of the majority density layer thermodynamic density of states owing to an increasing interlayer interaction between two layers near the Dirac point. The quantum capacitance near the neutrality point behaves like a square root of the total density α √{n } where the coefficient α decreases by increasing the charge-density imbalance between two layers. Furthermore, we show that the quantum capacitance changes linearly by the gate voltage. Our results can be verified by current experiments.

  18. Double Beta Decay Experiments with Thermal Detectors (United States)

    Alessandrello, A.; Brofferio, C.; Cremonesi, O.; Fiorini, E.; Giuliani, A.; Nucciotti, A.; Pavan, M.; Pessina, G.; Pirro, S.; Previtali, E.; Vanzini, M.; Zanotti, L.; Bucci, C.


    Massive low temperature particle detectors and their possible impacts on searches for neutrinoless double beta decay (O-DBD) are presented and discussed. In particular, the experimental work of the Milano group is described. Special relevance is given to the present status of the search for O-DBD of 130Te and to the possible expansion of this experiment in the near future. The most recent results obtained by the Milano-Gran Sasso collaboration with a 20 bolometer array are presented. On the basis of these results, the construction of a 42 kg array consisting of 56 TeO2 bolometers (CUORICINO project), to extend the sensitivity of the present experiment, has been proposed. CUORICINO should represent also a feasibility test for a large array of 1000 bolometers (CUORE project) aiming at the search for neutrinoless Double Beta Decay, Cold Dark Matter and Solar Axions with extremely high sensitivity.

  19. Double Image Design in Newspaper Production

    Directory of Open Access Journals (Sweden)

    Mario Barišić


    Full Text Available In the high circulation production of daily newspapers, a double image, double information is set under the rules of Infraredesign theory (Pap et al, 2010. The management of visible and near infrared is posted with process colors for color setting configured for conventional newspaper print. The place of imprint that has delimited information in vs (Visible Spectrum and nir (Near InfraRed is called “a print with an infrared effect,” or conditionally “a print with infrared colors.” Daily newspapers, as massive carriers of information made by printing technique, are receiving a new form of presentation: printed image with a built-in invisible image.

  20. Double papilla flap technique for dual purpose

    Directory of Open Access Journals (Sweden)

    P Mohan Kumar


    Full Text Available Marginal tissue recession exposes the anatomic root on the teeth, which gives rise to -common patient complaints. It is associated with sensitivity, tissue irritation, cervical abrasions, and esthetic concerns. Various types of soft tissue grafts may be performed when recession is deep and marginal tissue health cannot be maintained. Double papilla flap is an alternative technique to cover isolated recessions and correct gingival defects in areas of insufficient attached gingiva, not suitable for a lateral sliding flap. This technique offers the advantages of dual blood supply and denudation of interdental bone only, which is less susceptible to permanent damage after surgical exposure. It also offers the advantage of quicker healing in the donor site and reduces the risk of facial bone height loss. This case report presents the advantages of double papilla flap in enhancing esthetic and functional outcome of the patient.

  1. Amplitude determinant coupled cluster with pairwise doubles

    CERN Document Server

    Zhao, Luning


    Recently developed pair coupled cluster doubles (pCCD) theory successfully reproduces doubly occupied configuration interaction (DOCI) with mean field cost. However, the projective nature of pCCD makes the method non-variational and thus hard to improve systematically. As a variational alternative, we explore the idea of coupled-cluster-like expansions based on amplitude determinants and develop a specific theory similar to pCCD based on determinants of pairwise doubles. The new ansatz admits a variational treatment through Monte Carlo methods while remaining size-consistent and, crucially, polynomial cost. In the dissociations of LiH, HF, H2O and N2, the method performs very similarly to pCCD and DOCI, suggesting that coupled-cluster-like ansatzes and variational evaluation may not be mutually exclusive.

  2. Xanthogranulomatous Pyelonephritis with Incomplete Double Ureter

    Directory of Open Access Journals (Sweden)

    Yutaro Hayashi


    Full Text Available Introduction. Xanthogranulomatous pyelonephritis (XGP is a type of chronic renal inflammation that usually occurs in immunocompromised middle-aged women with chronic urinary tract infection or ureteral obstruction induced by the formation of ureteral stones. XGP with an incomplete double ureter is extremely rare. Case Presentation. A 76-year-old woman was referred to our department to undergo further examination for a left renal tumor that was detected by ultrasonography. Dynamic contrast computed tomography (CT revealed an enhanced tumor in the upper renal parenchyma. Laparoscopic radical nephrectomy was performed based on a preoperative diagnosis of renal cell carcinoma. Histological sections showed the aggregation of foam cells; thus, XGP was diagnosed. Conclusion. We herein report a rare case of XGP in the upper pole of the kidney, which might have been associated with an incomplete double ureter.

  3. Inviscid double wake model for stalled airfoils

    DEFF Research Database (Denmark)

    Marion, Lucas; Ramos García, Néstor; Sørensen, Jens Nørkær


    An inviscid double wake model based on a steady two-dimensional panel method has been developed to predict aerodynamic loads of wind turbine airfoils in the deep stall region. The separated flow is modelled using two constant vorticity sheets which are released at the trailing edge and at the sep......An inviscid double wake model based on a steady two-dimensional panel method has been developed to predict aerodynamic loads of wind turbine airfoils in the deep stall region. The separated flow is modelled using two constant vorticity sheets which are released at the trailing edge...... and at the separation point. A calibration of the code through comparison with experiments has been performed using one set of airfoils. A second set of airfoils has been used for the validation of the calibrated model. Predicted aerodynamic forces for a wide range of angles of attack (0 to 90 deg) are in overall good...

  4. Detecting double compression of audio signal (United States)

    Yang, Rui; Shi, Yun Q.; Huang, Jiwu


    MP3 is the most popular audio format nowadays in our daily life, for example music downloaded from the Internet and file saved in the digital recorder are often in MP3 format. However, low bitrate MP3s are often transcoded to high bitrate since high bitrate ones are of high commercial value. Also audio recording in digital recorder can be doctored easily by pervasive audio editing software. This paper presents two methods for the detection of double MP3 compression. The methods are essential for finding out fake-quality MP3 and audio forensics. The proposed methods use support vector machine classifiers with feature vectors formed by the distributions of the first digits of the quantized MDCT (modified discrete cosine transform) coefficients. Extensive experiments demonstrate the effectiveness of the proposed methods. To the best of our knowledge, this piece of work is the first one to detect double compression of audio signal.

  5. Energy Calibration of Double Chooz Detector (United States)

    Yang, Guang


    Reactor anti-neutrino oscillation experiment Double Chooz was designed to measure the mixing angle theta-13 with unprecedented sensitivity. The Double Chooz detector system consists of a main detector, an outer veto system and several calibration systems. The main detector has a cylindrical structure. It consists of the target vessel, a liquid scintillator loaded with Gd, surrounded by the gamma-catcher, a non-loaded liquid scintillator. A buffer region of non-scintillating liquid surrounds the gamma-catcher and serves to host 390 photomultiplier tubes and to decrease the level of accidental background. The Inner Veto region is outside the buffer, and the Outer Veto system covers all detector components. Far detector is operational and the near detector is under construction. The detector is calibrated with light sources, radioactive point sources, cosmics and natural radioactivity. In this presentation we will describe use of radioactive calibration sources and cross-checks performed with cosmics and natural radioactivity.

  6. Double quantum dots in carbon nanotubes (United States)

    von Stecher, Javier; Wunsch, Bernhard; Lukin, Mikhail; Demler, Eugene; Rey, Ana Maria


    We study the behavior of few-electrons confined in a double-well quantum dot in semiconducting carbon nanotubes. These carbon nanostructures exhibit richer physics than GaAs ones due to the additional valley degree of freedom. We calculate and characterize the low energy eigenstates in the presence of a magnetic field and double-well detuning. Spin-orbit coupling lifts the spin and valley degeneracy and, in the presence of exchange interactions, leads, at small detunings and weak magnetic fields, to a spin-valley antisymmetric two-electron ground state which is not a pure spin-singlet state. At large detuning, the strong Coulomb interactions accessible in carbon nanotubes can substantially modify the non-interacting eigenstates via higher orbital-level mixing. The latter manifest in current transport experiments by the disappearance of the Pauli blockade.

  7. Monitoring of Double Stud Wall Moisture Conditions in the Northeast

    Energy Technology Data Exchange (ETDEWEB)

    Ueno, K. [Building Science Corporation, Westford, MA (United States)


    Double-stud walls insulated with cellulose or low-density spray foam can have R-values of 40 or higher. However, double stud walls have a higher risk of interior-sourced condensation moisture damage, when compared with high-R approaches using exterior insulating sheathing.; Moisture conditions in double stud walls were monitored in Zone 5A (Massachusetts); three double stud assemblies were compared.

  8. Maxillary double lip: A case series with review of literature

    Directory of Open Access Journals (Sweden)

    Vela D Desai


    Full Text Available Double lip is a rare dental anomaly affecting either upper or lower lip or concurrently. It may be congenital or acquired. This deformity can affect the facial esthetics as it gets exaggerated while speaking, smiling, or chewing food. When it interferes with speech, double lip may cause potential functional problems. The purpose of this article is to review the literature on double lip and present a case series of maxillary double lip.

  9. A double patella-like condition secondary to synovial osteochondromatosis

    Directory of Open Access Journals (Sweden)

    Kajikawa Yoshiteru


    Full Text Available Abstract To our knowledge, this is the first case of synovial osteochondromatosis in a patient presenting with a double patella-like condition. The true duplication of the patella, which is called double patella, is extremely rare. In our case, the operative and histopathological findings showed that the double patella-like condition was secondarily induced by synovial osteochondromatosis. Synovial osteochondromatosis should be considered as a differential diagnosis for congenital double patella.

  10. Structure and stability of human hemoglobin microparticles prepared with a double emulsion technique. (United States)

    Cedrati, N; Bonneaux, F; Labrude, P; Maincent, P


    Hemoglobin solutions can be used as blood substitutes but they present some disadvantages often due to their rapid removal from the bloodstream after injection. A possible way of overcoming this problem is to trap hemoglobin inside particles. This study deals with the preparation, structure and stability of poly(lactic acid) and ethylcellulose microparticles containing human hemoglobin obtained with a double emulsion technique. We investigated the manufacturing process of these particles in order to increase the encapsulation ratio of hemoglobin. For this purpose, some parameters involved in the procedure were optimized, such as hemoglobin concentration and duration of stirring: hemoglobin loading increases with its concentration in the preparation and well-defined stirring time avoids a leakage of hemoglobin. Hemoglobin concentration, surfactant concentration i.e. poly(vinylic alcohol), amounts of polymer and solvent (methylene chloride), duration and speed of stirring. The microparticles were prepared with satisfactory yields (60 to 73%). They were spherical and their mean size was lower than 200 microns. The functional properties of entrapped hemoglobin were studied. The encapsulation did not alter hemoglobin and the oxygen affinity of the hemoglobin remained unmodified (P50 about 13.9 mm Hg in a Bis-Tris buffer pH 7.4 at 37 degrees C). Moreover, only low levels of methemoglobin could be detected (less than 3%). Besides, about 90% of encapsulated hemoglobin could be released from microparticles, with a speed related to the internal structure of the particles. The prepared microparticles were stored during one month at +4 degrees C. No degradation of the particle structure occurred and the functional properties of hemoglobin were preserved. These particles could provide a potential source of oxygen in the field of biotechnologies but any application for a transfusional purpose would first require a drastic reduction in particle size.

  11. [Double gall blader--surprise during operation]. (United States)

    Oprea, D; Maier, A; Costea, P


    Gall blader abnormalities are very rare. The diagnosis is difficult, more often appears during operation or necropsy. The authors present a clinical case with double gall blader, into a 50 years old man. The diagnosis appeared during laparoscopic cholecystectomy. The colecistectomy was performed for chronic cholelithiasis. Even it is rare, this pathology should be known, to avoid biliary ducts iatrogenic injuries during operations. The authors made a mustering of literature.

  12. Floral double mesiodentes: A rare case report. (United States)

    Singaraju, Gowri Sankar; Reddy, B Rama Mohan; Supraja, G; Reddy, K Narayana


    Mesiodens is the most commonly erupting supernumerary in the midline between two maxillary central incisors. Mesiodentes is a rare condition when mesiodens erupt in multiples, which may present as either labial or palatal to permanent central incisors. We report a rare case of double mesiodentes (non-syndromic mesiodentes) with floret like appearance. The presence of mesiodens has functional and esthetic implications. Careful radiographic evaluation should be done to prevent complications during their extraction.

  13. Tables of double beta decay data

    Energy Technology Data Exchange (ETDEWEB)

    Tretyak, V.I. [AN Ukrainskoj SSR, Kiev (Ukraine)]|[Strasbourg-1 Univ., 67 (France). Centre de Recherches Nucleaires; Zdesenko, Y.G. [AN Ukrainskoj SSR, Kiev (Ukraine)


    A compilation of experimental data on double beta decay is presented. The tables contain the most stringent known experimental limits or positive results of 2{beta} transitions of 69 natural nuclides to ground and excited states of daughter nuclei for different channels (2{beta}{sup -}; 2{beta}{sup +}; {epsilon}{beta}{sup +}; 2{epsilon}) and modes (0{nu}; 2{nu}; 0{nu}M) of decay. (authors). 189 refs., 9 figs., 3 tabs.

  14. Doubling Time for Nonexponential Families of Functions (United States)

    Gordon, Sheldon P.


    One special characteristic of any exponential growth or decay function f(t) = Ab[superscript t] is its unique doubling time or half-life, each of which depends only on the base "b". The half-life is used to characterize the rate of decay of any radioactive substance or the rate at which the level of a medication in the bloodstream decays as it is…

  15. Vitrectomy in double-perforation gunshot injury

    Directory of Open Access Journals (Sweden)

    Abd El Alim Mohamed A


    Full Text Available Ahmed Abd El Alim MohamedOphthalmology department, Ain Shams University, Cairo, EgyptObjective: This study sought to evaluate the result of pars plana vitrectomy in patients with gunshot wounds involving double perforation.Methods: This was a retrospective, noncomparative, interventional case series.Results: Eighteen patients (18 eyes with double-perforation gunshot injuries were treated from February 2010 to March 2012. The group included 16 men (88% and two women (11%; the mean age was 24 (15–33 years. In each case, vitrectomy was scheduled 1–6 weeks after repair of the entrance site. Associated retinal detachments were observed in two eyes (11%, retinal incarceration was observed surrounding the exit site in three eyes (16%, and retention of an intraocular foreign body was observed in two cases. After a follow-up period of 8 ± 2 months, two eyes (11% had achieved visual acuity (VA of 0.5, nine eyes (50% had achieved VA between 0.5 and 0.1, and seven eyes (38% had achieved VA between 0.1 and hand movement. The main reasons for functional failure (VA 0.1 to hand movement were macular dragging (due to fibrosis at the exit site near the macula in seven cases (38%, submacular hemorrhage in four cases (22%, and epimacular fibrosis in five cases (27%. All cases developed postoperative exotropia. One case (5% developed postoperative hemorrhage. No cases exhibited signs of postoperative redetachment.Conclusion: The outcome of pars plana vitrectomy in cases with double perforations is variable. Factors including the surgeon's skill level, the time to surgery, and the efficacy of the intraocular tamponade affect the postoperative outcome.Keywords: pars plana vitrectomy, gunshot injury, double perforation

  16. Nivolumab Doubles Survival for Patients with HNSCC. (United States)


    In patients with head and neck squamous cell carcinoma refractory to platinum-based chemotherapy, those treated with nivolumab had a 30% reduction in the risk of death compared with those assigned to receive one of three single-agent chemotherapies, according to a recent phase III trial. In addition, 1-year survival among nivolumab recipients was double that of those who received a chemotherapeutic, the current standard of care. ©2016 American Association for Cancer Research.

  17. The double helix and the 'wronged heroine'. (United States)

    Maddox, Brenda


    In 1962, James Watson, Francis Crick and Maurice Wilkins received the Nobel prize for the discovery of the structure of DNA. Notably absent from the podium was Rosalind Franklin, whose X-ray photographs of DNA contributed directly to the discovery of the double helix. Franklin's premature death, combined with misogynist treatment by the male scientific establishment, cast her as a feminist icon. This myth overshadowed her intellectual strength and independence both as a scientist and as an individual.

  18. Integrated double-sided silicon microstrip detectors

    Directory of Open Access Journals (Sweden)

    Perevertailo V. L.


    Full Text Available The problems of design, technology and manufacturing double-sided silicon microstrip detectors using standard equipment production line in mass production of silicon integrated circuits are considered. The design of prototype high-energy particles detector for experiment ALICE (CERN is presented. The parameters of fabricated detectors are comparable with those of similar foreign detectors, but they are distinguished by lesser cost.

  19. Double-Diffusive Convection in Rotational Shear (United States)


    have already been conducted to test the distortion of thermohaline 49 staircases and the channel propagation of acoustic signals (Bulters, 2013...models of ocean circulation (Radko 2013). In each of these instances, a clearer understanding of the small-scale dynamics of double diffusion would...REFERENCES Bulters, A. C., 2012: Three-dimensional structure of thermohaline staircases in the tropical north Atlantic and their effect on acoustic

  20. Why double-stranded RNA resists condensation (United States)

    Tolokh, Igor S.; Pabit, Suzette A.; Katz, Andrea M.; Chen, Yujie; Drozdetski, Aleksander; Baker, Nathan; Pollack, Lois; Onufriev, Alexey V.


    The addition of small amounts of multivalent cations to solutions containing double-stranded DNA leads to inter-DNA attraction and eventual condensation. Surprisingly, the condensation is suppressed in double-stranded RNA, which carries the same negative charge as DNA, but assumes a different double helical form. Here, we combine experiment and atomistic simulations to propose a mechanism that explains the variations in condensation of short (25 base-pairs) nucleic acid (NA) duplexes, from B-like form of homopolymeric DNA, to mixed sequence DNA, to DNA:RNA hybrid, to A-like RNA. Circular dichroism measurements suggest that duplex helical geometry is not the fundamental property that ultimately determines the observed differences in condensation. Instead, these differences are governed by the spatial variation of cobalt hexammine (CoHex) binding to NA. There are two major NA-CoHex binding modes—internal and external—distinguished by the proximity of bound CoHex to the helical axis. We find a significant difference, up to 5-fold, in the fraction of ions bound to the external surfaces of the different NA constructs studied. NA condensation propensity is determined by the fraction of CoHex ions in the external binding mode. PMID:25123663

  1. Double shell planar experiments on OMEGA (United States)

    Dodd, E. S.; Merritt, E. C.; Palaniyappan, S.; Montgomery, D. S.; Daughton, W. S.; Schmidt, D. W.; Cardenas, T.; Wilson, D. C.; Loomis, E. N.; Batha, S. H.; Ping, Y.; Smalyuk, V. A.; Amendt, P. A.


    The double shell project is aimed at fielding neutron-producing capsules at the National Ignition Facility (NIF), in which an outer low-Z ablator collides with an inner high-Z shell to compress the fuel. However, understanding these targets experimentally can be challenging when compared with conventional single shell targets. Halfraum-driven planar targets at OMEGA are being used to study physics issues important to double shell implosions outside of a convergent geometry. Both VISAR and radiography through a tube have advantages over imaging through the hohlraum and double-shell capsule at NIF. A number physics issues are being studied with this platform that include 1-d and higher dimensional effects such as defect-driven hydrodynamic instabilities from engineering features. Additionally, the use of novel materials with controlled density gradients require study in easily diagnosed 1-d systems. This work ultimately feeds back into the NIF capsule platform through manufacturing tolerances set using data from OMEGA. Supported under the US DOE by the LANS, LLC under contract DE-AC52-06NA25396. LA-UR-17-25386.

  2. The 'double cortex' syndrome on MRI. (United States)

    Hashimoto, R; Seki, T; Takuma, Y; Suzuki, N


    We report a 6-year-old girl with diffuse subcortical heterotopia (band heterotopia), an unusual type of ectopic gray matter on magnetic resonance imaging (MRI). Her cerebral parenchyma had four layers consisting of cortex, thin outer white matter, diffuse subcortical heterotopia, and inner white matter around the lateral ventricles, giving the appearance of a 'double cortex'. The overlying cortex had midly broad gyri, especially in the frontal lobes. MRI showed the appearance of laminar heterotopia, a classical pathological entity. The double cortex syndrome is presumably a radiological delineation of laminar heterotopia. Her development was slightly delayed and she was clumsy and easily upset, with poor impulse control. However, her daily life was largely unaffected in spite of the severe abnormalities on MRI. She had abnormal movements during sleep, and sleeping EEG showed high voltage spindles in the bilateral frontal areas but no epileptic discharges. It could not be determined whether or not these movements were epileptic. The double cortex syndrome, an anomaly of the central nervous system associated with mental retardation, epilepsy, behavioral problems, and exclusive occurrence in girls, will be established as a clinico-radiological entity.

  3. Aerodynamic Analysis Over Double Wedge Airfoil (United States)

    Prasad, U. S.; Ajay, V. S.; Rajat, R. H.; Samanyu, S.


    Aeronautical studies are being focused more towards supersonic flights and methods to attain a better and safer flight with highest possible performance. Aerodynamic analysis is part of the whole procedure, which includes focusing on airfoil shapes which will permit sustained flight of aircraft at these speeds. Airfoil shapes differ based on the applications, hence the airfoil shapes considered for supersonic speeds are different from the ones considered for Subsonic. The present work is based on the effects of change in physical parameter for the Double wedge airfoil. Mach number range taken is for transonic and supersonic. Physical parameters considered for the Double wedge case with wedge angle (ranging from 5 degree to 15 degree. Available Computational tools are utilized for analysis. Double wedge airfoil is analysed at different Angles of attack (AOA) based on the wedge angle. Analysis is carried out using fluent at standard conditions with specific heat ratio taken as 1.4. Manual calculations for oblique shock properties are calculated with the help of Microsoft excel. MATLAB is used to form a code for obtaining shock angle with Mach number and wedge angle at the given parameters. Results obtained from manual calculations and fluent analysis are cross checked.

  4. Academic knowing in/through double perspectives

    Directory of Open Access Journals (Sweden)

    Margareta Melin


    Full Text Available This article explores the cultures and learning practices of four academic schools with an expressed wish to bridge the gap between traditional academic and arts or journalistic practices. Pierre Bourdieu, the French sociologist, termed them allodoxic, in that they challenge the traditional academic way of thinking and doing. Results from two research projects, spanning over 5 years, employing a multitude of methods, have been used in this article. The results show that these challenging bridging attempts create conflictual cultures. First, faculties with different backgrounds are employed and they bring with them their respective habitus and doxa (Bourdieu, which is manifested in their different epistemologies, doxas. Despite a strong will to work interdisciplinarily, conflicts (destructive arise particularly around epistemological and pedagogic issues. Second, I show that students at these schools have had double-perspective learning, through theoretical and practice-based methods, despite little help from their lecturers who have high ideals but little actual knowledge themselves of working in/through a double perspective. In many cases, through trial-and-error processes, students have appropriated embodied knowledge of a double perspective, which has given them surplus value when compared with learning through only traditional academic learning practices. It gives reflexive insights and understandings as well as transferrable skills highly useful in professional life. I finally argue that allodoxic conflictual cultures actually construct new ways of knowing through continuous discussions and meetings between faculties with different competences.

  5. Double entry bookkeeping vs single entry bookkeeping

    Directory of Open Access Journals (Sweden)

    Ileana Andreica


    Full Text Available Abstract: A financial management eficiently begin, primarily, with an accounting record kept in the best possible conditions, this being conditioned on the adoption of a uniform forms, rational, clear and simple accounting. Throughout history, there have been known two forms of accounting: the simple and double entry. Romanian society after 1990 underwent a substantial change in social structure, the sector on which put a great emphasis being private, that of small manufacturers, peddler, freelance, who work independently and authorized or as associative form (family enterprises, various associations (owners, tenants, etc., liberal professions, etc.. They are obliged to keep a simple bookkeeping, because they have no juridical personality. Companies with legal personality are required to keep double entry bookkeeping; therefore, knowledge and border demarcation between the two forms of organisation of accounting is an essential. The material used for this work is mainly represented by the financial and accounting documents, by the analysis of the economic, by legislative updated sources, and as the method was used the comparison method, using hypothetical data, in case of an authorized individual and a legal entity. Based on the chosen material, an authorized individual (who perform single entry accounting system and a juridical entity (who perform double entry accounting system were selected comparative case studies, using hypothetical data, were analysed advantages and disadvantages in term of fiscal, if using two accounting systems, then were highlighted some conclusion that result.

  6. Perturbative quantum gravity in double field theory

    Energy Technology Data Exchange (ETDEWEB)

    Boels, Rutger H.; Horst, Christoph [II. Institut für Theoretische Physik, Universität Hamburg,Luruper Chaussee 149, D- 22761 Hamburg (Germany)


    We study perturbative general relativity with a two-form and a dilaton using the double field theory formulation which features explicit index factorisation at the Lagrangian level. Explicit checks to known tree level results are performed. In a natural covariant gauge a ghost-like scalar which contributes even at tree level is shown to decouple consistently as required by perturbative unitarity. In addition, a lightcone gauge is explored which bypasses the problem altogether. Using this gauge to study BCFW on-shell recursion, we can show that most of the D-dimensional tree level S-matrix of the theory, including all pure graviton scattering amplitudes, is reproduced by the double field theory. More generally, we argue that the integrand may be reconstructed from its single cuts and provide limited evidence for off-shell cancellations in the Feynman graphs. As a straightforward application of the developed technology double field theory-like expressions for four field string corrections are derived.

  7. Double-Difference Tomography for Sequestration MVA

    Energy Technology Data Exchange (ETDEWEB)

    Westman, Erik


    Analysis of synthetic data was performed to determine the most cost-effective tomographic monitoring system for a geologic carbon sequestration injection site. Double-difference tomographic inversion was performed on 125 synthetic data sets: five stages of CO2 plume growth, five seismic event regions, and five geophone arrays. Each resulting velocity model was compared quantitatively to its respective synthetic velocity model to determine an accuracy value. The results were examined to determine a relationship between cost and accuracy in monitoring, verification, and accounting applications using double-difference tomography. The geophone arrays with widely-varying geophone locations, both laterally and vertically, performed best. Additionally, double difference seismic tomography was performed using travel time data from a carbon sequestration site at the Aneth oil field in southeast Utah as part of a Department of Energy initiative on monitoring, verification, and accounting (MVA) of sequestered CO2. A total of 1,211 seismic events were recorded from a borehole array consisting of 22 geophones. Artificial velocity models were created to determine the ease with which different CO2 plume locations and sizes can be detected. Most likely because of the poor geophone arrangement, a low velocity zone in the Desert Creek reservoir can only be detected when regions of test site containing the highest ray path coverage are considered. MVA accuracy and precision may be improved through the use of a receiver array that provides more comprehensive ray path coverage.

  8. Visual mislocalization during double-step saccades

    Directory of Open Access Journals (Sweden)

    Eckart eZimmermann


    Full Text Available Visual objects presented briefly at the time of saccade onset appear compressed toward the saccade target. Compression strength depends on the presentation of a visual saccade target signal and is strongly reduced during the second saccade of a double-step saccade sequence (Zimmermann et al., 2014; 2014. Here, I tested whether perisaccadic compression is linked to saccade planning by contrasting two double-step paradigms. In the same-direction double-step paradigm, subjects were required to perform two rightward 10° saccades successively. At various times around execution of the saccade sequence a probe dot was briefly flashed. Subjects had to localize the position of the probe dot after they had completed both saccades. I found compression of visual space only at the time of the first but not at the time of the second saccade. In the reverse-direction paradigm, subjects performed first a rightward 10° saccade followed by a leftward 10° saccade back to initial fixation. In this paradigm compression was found in similar magnitude during both saccades. Analysis of the saccade parameters did not reveal indications of saccade sequence preplanning in this paradigm. I therefore conclude that saccade planning, rather than saccade execution factors, is involved in perisaccadic compression.

  9. The GS09 double parton distribution functions (United States)

    Gaunt, J. R.

    It is anticipated that hard double parton scattering (DPS) will occur frequently in the collisions of the LHC, producing interesting signals and significant backgrounds to certain single scattering processes. In order to make theoretical predictions of double scattering rates and properties, the double parton distributions (dPDFs) D_p^{j_1j_2}(x_1,x_2;Q_A,Q_B) are required. We discuss the first publicly available set of equal-scale (Q_A=Q_B) leading order dPDFs -- the GS09 dPDFs. A brief account is given describing how pQCD evolution effects and sum rule constraints (the latter derived by us) have been incorporated into this set of dPDFs. We then present a summary of a phenomenological investigation into same-sign W pair production conducted using GS09. In this, the DPS signal produced using GS09 is compared with that obtained using simple products of single PDFs multiplied by (1-x_1-x_2)^n, and the single scattering backgrounds (W+-W+-jj, di-boson and heavy flavour) are carefully calculated. It is found that the correlations in GS09 manifest themselves in non-trivial kinematic correlations between the W bosons. However, it is unlikely that these correlations will be measurable at the LHC in the near future owing to the fact that the background is significant even after cuts.

  10. 40 CFR 721.5547 - Antimony double oxide. (United States)


    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Antimony double oxide. 721.5547... Substances § 721.5547 Antimony double oxide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substances identified generically as antimony double oxide (PMNs P-95-677 and P...

  11. Measurements of Neglected Double Stars: December 2016 Report (United States)

    Carro, Joseph


    This article presents measurements of 36 neglected double stars and one double star. The stars were selected from the Washington Double Star Catalog published by the United States Naval Observatory. The photographs were taken by remote telescopes. The measurements were done by the author.

  12. Clinical and Radiographic Evaluation of Double Teeth in Primary ...

    African Journals Online (AJOL)


    Jan 16, 2016 ... KEYWORDS: Dental anomaly, double teeth, fusion, germination, primary dentition. Clinical and Radiographic Evaluation of Double ... and Pediatric Dentistry departments between. February 2009 and April 2015. ... Type III: Two fused crowns, double conical root. [Figure 1c]. • Type IV: Two fused crowns, two ...

  13. On efficiency of some ratio estimators in double sampling design ...

    African Journals Online (AJOL)

    In this paper, three sampling ratio estimators in double sampling design were proposed with the intention of finding an alternative double sampling design estimator to the conventional ratio estimator in double sampling design discussed by Cochran (1997), Okafor (2002) , Raj (1972) and Raj and Chandhok (1999).

  14. Cyclone frequency in east asia and double-cyclones


    Umemoto, Tohru


    Japanese meteorologists call a certain type of cyclone "Futatsudama-teikiatsu" (Double-cyclone). The relationships between frequencies of extratropical cyclones and Double-cyclones were studied. Using a 2° latitude/longitude grid covering East Asia, three high frequency belts were found. Double-cyclones were classified into three types. Features of occurrence of these three types were discussed.

  15. Testing Intelligently Includes Double-Checking Wechsler IQ Scores (United States)

    Kuentzel, Jeffrey G.; Hetterscheidt, Lesley A.; Barnett, Douglas


    The rigors of standardized testing make for numerous opportunities for examiner error, including simple computational mistakes in scoring. Although experts recommend that test scoring be double-checked, the extent to which independent double-checking would reduce scoring errors is not known. A double-checking procedure was established at a…

  16. Double-planting can affect gains from weed control treatments (United States)

    David B. South


    Double-planting is the practice of planting two seedlings at every planting spot. When both seedlings survive, then either the less vigorous seedling is removed or each seedling is given an equal chance of being removed. Some researchers double-plant so that tree growth among experimental plots is not affected by initial differences in stocking. However, double-...

  17. Comparing and Selecting Generalized Double Ring Network Structures

    DEFF Research Database (Denmark)

    Pedersen, Jens Myrup; Knudsen, Thomas Phillip; Madsen, Ole Brun


    N2R(p;q) network structures were introduced recently as a generalization of double rings, and they were shown to be superior compared to double rings in terms of average distance and diameter. For a given number of nodes, there is only one double ring, but often more different N2R(p;q) structures...

  18. Rare Case of Double Looped Ansa Cervicalis Associated with its ...

    African Journals Online (AJOL)

    fibers of C1‑C3 nerves arose from this loop and ran obliquely downwards superficial to CCA and branched out to supply the infrahyoid muscles. Rare Case of Double Looped Ansa ... Keywords: Ansa cervicalis, Double loop, Nerve muscle transplant, Variation ... categorized as type 3 with the prevalence of 4% and double.

  19. Double diabetes: an emerging disease in children and young adults ...

    African Journals Online (AJOL)

    Prevention of childhood obesity by encouraging physical activities and dietary control would prevent double diabetes. Conclusion: Double diabetes is increasing in children and young adults. A high index of suspicion is required in obese children with diabetes. Keywords: Double diabetes, Emerging problem, Children, ...

  20. The double identity of doubling: Evidence for the phonology-morphology split. (United States)

    Berent, Iris; Bat-El, Outi; Vaknin-Nusbaum, Vered


    Duality of patterning, is, by hypothesis, a universal design feature of language. Every language constructs words from meaningful units (morphemes), which, in turn, are comprised of meaningless phonological elements (e.g., segments, syllables). But whether the language faculty does, in fact, include a separate morphological level, distinct from the phonology, is a matter of controversy. To elucidate the role of morphology, here we ask whether morphological forms are constrained by putatively universal combinatorial principles, distinct from those applying to phonological patterns. Our research exploits the structural ambiguity of doubling. Doubling (e.g., trafraf) is open to two competing interpretations-as either a purely phonological form, or as a complex morphological structure that is systematically linked to meaning (e.g., trafraf is the diminutive of traf). Our experiments show that responses to doubling (trafraf) shift radically, depending on its level of analysis. Viewed as a meaningless phonological form, doubling is dispreferred irrespective of its kind (i.e., trafraf is as bad as traftaf, even though the latter violates a morphological constraint on contiguity). But once doubling is systematically linked to meaning (i.e., as a morphological structure), the doubling dislike shifts into a reliable preference, and an additional constraint on its contiguity arises (i.e., trafraf>traftaf). Remarkably, the dissociation between morphological and phonological doubling emerges regardless of whether morphological reduplication is abundant in participants' language (in Hebrew) or relatively rare (in English). These results suggest the existence of distinct linguistic constraints that preferentially target the morphological vs. phonological levels. We discuss various explanations for the origins of these restrictions. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. An uncommon variant of double-chambered right ventricle masquerading as double-chambered left ventricle. (United States)

    Baritakis, Nikolaos; Grapsas, Nikolaos; Kotsalos, Andreas; Davlouros, Periklis


    We present a rare case of a double-chambered right ventricle masquerading as a double-chambered left ventricle, which was found incidentally on cardiac imaging in an adult female patient with atypical chest pain. The most common form of double-chambered right ventricle is characterized by compartmentalization of the right ventricle by muscular bands into 2 distinct chambers. The main features of this malformation are a pressure gradient between the 2 compartments, and the frequent (up to 90%) association with a membranous ventricular septal defect. In our case, the muscular band dividing the right ventricle was located in the inferoseptal part of the latter, creating a diminutive cavity that had no communication with the main right ventricle but communicated with the left ventricle creating the false impression of a double-chambered left ventricle. This constitutes a rare variant of double-chambered right ventricle with unknown clinical implications. © The Author 2017. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.

  2. Formation of Double Neutron Stars, Millisecond Pulsars and Double Black Holes (United States)

    van den Heuvel, Edward P. J.


    The 1982 model for the formation of Hulse-Taylor binary radio pulsar PSR B1913+16 is described, which since has become the `standard model' for the formation of the double neutron stars, confirmed by the 2003 discovery of the double pulsar system PSR J0737-3039AB. A brief overview is given of the present status of our knowledge of the double neutron stars, of which 15 systems are presently known. The binary-recycling model for the formation of millisecond pulsars is described, as put forward independently by Alpar et al. (1982), Radhakrishnan & Srinivasan (1982) and Fabian et al. (1983). This now is the `standard model' for the formation of these objects, confirmed by the discovery in 1998 of the accreting millisecond X-ray pulsars. It is noticed that the formation process of close double black holes has analogies to that of close double neutron stars, extended to binaries with larger initial component masses, although there are also considerable differences in the physics of the binary evolution at these larger masses.

  3. Role of effective distance in the fission mechanism study by the double-energy measurement for uranium isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Baba, Hiroshi; Saito, Tadashi; Takahashi, Naruto [Osaka Univ., Suita (Japan)] [and others


    Fission product kinetic energies were measured by the double-energy method for thermal-neutron fission of {sup 235,233}U and proton-induced fission of {sup 238}U at the 15.8-MeV excitation. From the obtained energy-mass correlation data, the kinetic-energy distribution was constructed from each mass bin to evaluate the first moment of the kinetic energy for a given fragment mass. The resulting kinetic energy was then converted to the effective distance between the charge centers at the moment of scission. The effective distances deduced for the proton-induced fission was concluded to be classified into two constant values, one for asymmetric and the other for symmetric mode, irrespective of the mass though an additional component was further extracted in the asymmetric mass region. This indicates that the fission takes place via two well-defined saddles, followed by the random neck rupture. On the contrary, the effective distances obtained for thermal-neutron induced fission turned out to lie along the contour line at the same level as the equilibrium deformation in the two-dimensional potential map. This strongly suggests that it is essentially a barrier-penetrating type of fission rather than the over-barrier fission. (author). 73 refs.

  4. Laboratory observation of multiple double layer resembling space plasma double layer (United States)

    Alex, Prince; Arumugam, Saravanan; Sinha, Suraj


    Perceptible double layer consisting of more than one layers were produced in laboratory using a double discharge plasma setup. The confinement of oppositely charged particles in each layer with sharply defined luminous boarder is attributed to the self-organization scenario. This structure is generated in front of a positively biased electrode when the electron drift velocity (νd) exceeds 1.3 times the electron thermal velocity (νte) . Stable multiple double layer structures were observed only between 1.3 νte organized criticality in the emergence of turbulence. The algebraic decaying tale of the autocorrelation function and power law behavior in the power spectrum are consistent with the observation.

  5. Design and delivery of the diamond double double bend achromat project

    Energy Technology Data Exchange (ETDEWEB)

    Kay, J., E-mail:; Hammond, N. P.; Thomson, A. [Diamond Light Source, Didcot, Oxfordshire, UK, OX11 0DE (United Kingdom)


    A major project is underway at Diamond Light Source to remove one of the 24 Double Bend Achromat (DBA) Storage Ring cells and replace it with a Double Double Bend Achromat (DDBA). In this way a new Insertion Device (ID) straight can be created and so ID light can be produced and delivered to a beamline previously only capable of receiving Bending Magnet (BM) radiation. This project is in support of the micro-focus Protein Crystallography (MX) beamline VMX-m which is scheduled to take users towards the end of 2017. This paper describes the Engineering Design of the DDBA project in more detail and gives the current status of the project.

  6. Comparative Analysis of Guided Modal Properties of Double-Positive and Double-Negative Metamaterial Slab Waveguides

    Directory of Open Access Journals (Sweden)

    K. Y. Kim


    Full Text Available The guided modal properties of double-positive and double-negative metamaterial slab waveguides are numerically analyzed and compared when varying the dielectric and magnetic constants. As the cutoff frequencies of both slab waveguides remained unchanged when the absolute value of the refractive index was kept invariant, this enabled an effective comparison of the respective guided modes. Thus, the guided mode dispersion characteristics of the double-positive and double-negative slab waveguides were analyzed and compared, including several higher order modes. As a result, this comparative analysis provides greater physical insights and a better understanding of the guided modal characteristics of double-negative metamaterial slab waveguides.

  7. Design studies for the Double Chooz trigger

    Energy Technology Data Exchange (ETDEWEB)

    Cucoanes, Andi Sebastian


    The main characteristic of the neutrino mixing effect is assumed to be the coupling between the flavor and the mass eigenstates. Three mixing angles ({theta}{sub 12}, {theta}{sub 23}, {theta}{sub 13}) are describing the magnitude of this effect. Still unknown, {theta}{sub 13} is considered very small, based on the measurement done by the CHOOZ experiment. A leading experiment will be Double Chooz, placed in the Ardennes region, on the same site as used by CHOOZ. The Double Chooz goal is the exploration of {proportional_to}80% from the currently allowed {theta}{sub 13} region, by searching the disappearance of reactor antineutrinos. Double Chooz will use two similar detectors, located at different distances from the reactor cores: a near one at {proportional_to}150 m where no oscillations are expected and a far one at 1.05 km distance, close to the first minimum of the survival probability function. The measurement foresees a precise comparison of neutrino rates and spectra between both detectors. The detection mechanism is based on the inverse {beta}-decay. The Double Chooz detectors have been designed to minimize the rate of random background. In a simplified view, two optically separated regions are considered. The target, filled with Gd-doped liquid scintillator, is the main antineutrino interaction volume. Surrounding the target, the inner veto region aims to tag the cosmogenic muon background which hits the detector. Both regions are viewed by photomultipliers. The Double Chooz trigger system has to be highly efficient for antineutrino events as well as for several types of background. The trigger analyzes discriminated signals from the central region and the inner veto photomultipliers. The trigger logic is fully programmable and can combine the input signals. The trigger conditions are based on the total energy released in event and on the PMT groups multiplicity. For redundancy, two independent trigger boards will be used for the central region, each of

  8. Ferroelectricity in d0 double perovskite fluoroscandates (United States)

    Charles, Nenian; Rondinelli, James M.


    Ferroelectricity in strain-free and strained double perovskite fluorides, Na3ScF6 and K2NaScF6 , is investigated using first-principles density functional theory. Although the experimental room temperature crystal structures of these fluoroscandates are centrosymmetric, i.e., Na3ScF6 (P 21/n ) and K2NaScF6 (F m 3 ¯m ), lattice dynamical calculations reveal that soft polar instabilities exist in each prototypical cubic phase and that the modes harden as the tolerance factor approaches unity. Thus the double fluoroperovskites bear some similarities to A B O3 perovskite oxides; however, in contrast, these fluorides exhibit large acentric displacements of alkali metal cations (Na, K) rather than polar displacements of the transition metal cations. Biaxial strain investigations of the centrosymmetric and polar Na3ScF6 and K2NaScF6 phases reveal that the paraelectric structures are favored under compressive strain, whereas polar structures with in-plane electric polarizations (˜5 -18 μ C cm-2 ) are realized at sufficiently large tensile strains. The electric polarization and stability of the polar structures for both chemistries are found to be further enhanced and stabilized by a coexisting single octahedral tilt system. Our results suggest that polar double perovskite fluorides may be realized by suppression of octahedral rotations about more than one Cartesian axis; structures exhibiting in- or out-of-phase octahedral rotations about the c axis are more susceptible to polar symmetries.

  9. Double orifice mitral valve: A case report

    Directory of Open Access Journals (Sweden)

    Musić Ljilja


    Full Text Available Introduction. Double orifice mitrol valve (DOMV is a very rare congenital heart defect. Case report. We reported 20-year-old male referred to our center due to evaluation of his cardiologic status. He was operated on shortly after birth for a tracheoesophageal fistula. Accidentally, echocardiography examination at the age of 4 years revealed double orifice mitral valve (DOMV without the presence of mitral regurgitation, as well as mitral stenosis, with normal dimensions of all cardiac chambers. The patient was asymptomatic, even more he was a kick boxer. His physical finding was normal. Electrocardiography showed regular sinus rhythm, incomplete right bundle branch block. Transthoracic echocardiography (TTE examination revealed the normal size of the left atrial, mitral leaflets were slightly more redundant. The left and right heart chambers, aorta, tricuspid valve and pulmonary artery valve were normal. During TTE examination on a short axis view two asymmetric mitral orifices were seen as a double mitral orifice through which we registered normal flow, without regurgitation and mitral stenosis. Transesophageal echocardiography (TEE examination from the transgastric view at the level of mitral valve, showed 2 single asymmetric mitral orifices separated by fibrous tissue, mitral leaflet with a separate insertion of hordes for each orifice. Conclusion. The presented patient with DOMV is the only one recognized in our country. The case is interesting because during 16-year a follow-up period there were no functional changes despite the fact that he performed very demanded sport activities. This is very important because there is no information in the literature about that.

  10. Double obstruction of ureter: A diagnostic challenge

    Directory of Open Access Journals (Sweden)

    Pankaj Halder


    Full Text Available Introduction: Isolated obstruction of the ureteropelvic junction and the vesico-ureteric junction are the two most common causes of hydronephrosis in a pediatric population. [1] They do not pose diagnostic difficulties when are present alone but when together can be difficult to diagnose. Here, we discuss the problems we faced when we encountered these two anomalies in the same ureter and the way in which we managed them. Aim: To assess the difficulties in diagnosis of pediatric patients who present with both ureteropelvic junction obstruction (UPJO and vesico-ureteric junction obstruction (VUJO in the ipsilateral ureter and their management protocol. Materials and Methods: This is a retrospective study. The study period is from 1 January 2004 to 31 December 2011. Out of 254 children who were diagnosed to have hydronephrosis due to UPJO in our institute, 5 patients (in the age range of 5 to 10 years had both UPJO and VUJO in the ipsilateral ureter. The problems we faced in diagnosing the two conditions are mentioned with a literature review. Results: Operative intervention was used in four out of five patients; none of the patients had an accurate diagnosis before surgery. All patients were suspected of having double obstruction during pyeloplasty when appropriate size double J stent could not be negotiated through the vesicoureteric junction into the bladder. Postoperative nephrostogram confirmed the diagnosis in all patients. Conclusion: Children with double obstruction of the ipsilateral ureter present as a diagnostic dilemma. Because of the rarity of this condition it can escape the eye of even an astute clinician. Early diagnosis can be made if this condition is kept in mind while treating any hydronephrosis due to UPJO or UVJO.

  11. Double exchange model for magnetic hexaborides. (United States)

    Pereira, Vitor M; Lopes dos Santos, J M B; Castro, Eduardo V; Neto, A H Castro


    A microscopic theory for rare-earth ferromagnetic hexaborides, such as Eu1-xCaxB6, is proposed on the basis of the double-exchange Hamiltonian. In these systems, the reduced carrier concentrations place the Fermi level near the mobility edge, introduced in the spectral density by the disordered spin background. We show that the transport properties such as the Hall effect, magnetoresistance, frequency dependent conductivity, and dc resistivity can be quantitatively described within the model. We also make specific predictions for the behavior of the Curie temperature T(C) as a function of the plasma frequency omega(p).

  12. Routing in double layered satellite network (United States)

    Fan, Xiaofeng; Fei, Gao


    With the fast development of aviation technology and network, satellite communication systems are not limited to a signal satellite any more, they are now oriented to network. Double LEO/MEO network can separate network manage from traffic in physical layer in order to manage total network and operate central routing. At last, aiming at the problem of the frequency link switch, we give a new routing protocol (OSPF_SAT) based on OSPF routing protocol. The optimized strategy routing algorithm and is applied to the model, with the result of getting less link switch ratio.

  13. Double maxima of 11-year solar cycles (United States)

    Krivodubskij, V. N.


    The explanation of the observed phenomenon of double peaks of the 11 year sunspot cycles is proposed. The scenario involves five processes of reconstruction of magnetism in the solar convective zone (SCZ): ω effect, magnetic buoyancy, macroscopic turbulent diamagnetism, rotary \\downtriangle ρ effect and meridional circulation. It was established that the reconstruction of magnetism in high-latitude and equatorial domains of the SCZ occurs in different modes. Two time-shifted waves of the toroidal field to the solar surface play a key role in the proposed mechanism in the equatorial domain.

  14. Elderly donors double kidney transplantation (DKT)


    Méndez-Chacón, Pedro; Facultad de Medicina, UNMSM. Lima, Perú; Servicio Nefrología. Servicio de Patología. Hospital Nacional Edgardo Rebagliati Martins. Lima, Perú; Vidalón, Armando; Facultad de Medicina, UNMSM. Lima, Perú; Servicio Nefrología. Servicio de Patología. Hospital Nacional Edgardo Rebagliati Martins. Lima, Perú; Medina, Mario; Servicio Nefrología. Servicio de Patología. Hospital Nacional Edgardo Rebagliati Martins. Lima, Perú; Camacho, Miguel; Servicio Nefrología. Servicio de Patología. Hospital Nacional Edgardo Rebagliati Martins. Lima, Perú; Somocurcio, José; Servicio Nefrología. Servicio de Patología. Hospital Nacional Edgardo Rebagliati Martins. Lima, Perú


    Objective: To use both kidneys of an elderly donor in the same receptor and remark the importance of kidney histology as selector method. Materials and Methods: We evaluate the selection and surveillance of 11 patients who received double kidney of cadaver elderly donors. The ten donors’ mean serum creatinine was 1,3 mg/dL, and the mean age was 63 years old (range 56 to 73 years), the receptor’s mean age 53 years. Both kidneys were examined by frozen wedge biopsy. Quantification of damaged ti...

  15. Double issue of the Bulletin for Ascension

    CERN Multimedia

    Publications Section (ETT)


    Because Thursday 20 May and Friday 21 May are official holidays, there will be a double issue of the Bulletin (No. 21-22/2004) covering the weeks of 17 and 24 May. The deadline for texts to appear in this issue will be midday on Tuesday, 11 May, both for articles submitted to the Publications Section and for those of the Staff Association. Articles for the following issue of the Bulletin (No. 23/2004), which will cover the week of 31 May, should be submitted by midday on Tuesday 25 May at the latest.

  16. Structures of Thermal Double Donors in Silicon


    Pesola, M.; Joo Lee, Young; von Boehm, J.; Kaukonen, M.; Nieminen, Risto M.


    Accurate total-energy calculations are used to study the structures and formation energies of oxygen chains as models for thermal double donors (TDD's) in Si. We find that the first three TDD's (TDD0–TDD2) consist of one four-member ring, with one or two adjacent interstitial O atoms. These metastable TDD's form bistable negative-U systems with the corresponding stable, electrically inactive staggered structures. The TDD3-TDD7 structures are found to consist of four-member rings with adjacent...

  17. The high sensitivity double beta spectrometer TGV (United States)

    Briancon, Ch.; Brudanin, V. B.; Egorov, V. G.; Janout, Z.; Koníček, J.; Kovalík, A.; Kovalenko, V. E.; Kubašta, J.; Pospíšil, S.; Revenko, A. V.; Rukhadze, N. I.; Salamatin, A. V.; Sandukovsky, V. G.; Štekl, I.; Timkin, V. V.; Tsupko-Sitnikov, V. V.; Vorobel, V.; Vylov, Ts.


    A high sensitivity double beta spectrometer TGV (Telescope Germanium Vertical) has been developed. It is based on 16 HPGe detectors of volume 1200 × 6 mm 3 each in the same cryostat. The TGV spectrometer was proposed for the study of ultrarare nuclear processes (e.g. 2νββ, 0νββ, 2νEC/EC). Details of the TGV spectrometer construction are described, the principles of background suppression, the results of Monte Carlo simulations and the results of test background measurements (in Dubna and Modane underground laboratory) are provided.

  18. NGC 4340: Double Bar + Fossil Nuclear Ring


    Erwin, P.; Beltran, J. C. Vega; Beckman, J. E.


    NGC 4340 is a double-barred SB0 galaxy in the Virgo cluster (Wozniak et al. 1995). Here, we present evidence that this galaxy also posseses a luminous stellar nuclear ring of relatively old stars with little or no gas. The ring lies just outside the inner bar, at the probable inner inner Lindblad resonance (IILR) of the outer bar. Careful inspection of the isophotes and unsharp masks shows that the two bars are slightly misaligned, which suggests they may be independently rotating.

  19. Minimally doubled fermions at one loop (United States)

    Capitani, Stefano; Weber, Johannes; Wittig, Hartmut


    Minimally doubled fermions have been proposed as a cost-effective realization of chiral symmetry at non-zero lattice spacing. Using lattice perturbation theory at one loop, we study their renormalization properties. Specifically, we investigate the consequences of the breaking of hyper-cubic symmetry, which is a typical feature of this class of fermionic discretizations. Our results for the quark self-energy indicate that the four-momentum undergoes a renormalization which is linearly divergent. We also compute renormalization factors for quark bilinears, construct the conserved vector and axial-vector currents and verify that at one loop the renormalization factors of the latter are equal to one.

  20. Triple Pelvic Osteotomy and Double Pelvic Osteotomy. (United States)

    Guevara, Francisco; Franklin, Samuel P


    Triple and double pelvic osteotomy (TPO, DPO) are performed with the goal of increasing acetabular ventro-version, increasing femoral head coverage, and decreasing femoral head subluxation. Since the first descriptions of TPO, there have been modifications in technique, most notably omission of the ischial osteotomy for DPO, and improvements in the implants, including availability of locking TPO/DPO bone plates. Associated complication rates seem to have declined accordingly. The most salient questions regarding these procedures remain what selection criteria should be used to identify candidates and whether halting or preventing osteoarthritis is necessary to consider these surgeries clinically beneficial. Copyright © 2017 Elsevier Inc. All rights reserved.

  1. Jonckheere Double Star Photometry - Part VII: Aquarius (United States)

    Knapp, Wilfried R. A.


    If any double star discoverer is in urgent need of photometry then it is Jonckheere. There are over 3000 Jonckheere objects listed in the WDS catalog and a good part of them with magnitudes obviously far too bright. This report covers the Jonckheere objects in the constellation Aquarius. One image per object was taken with V-filter to allow for visual magnitude measurement by differential pho-tometry. All objects were additionally checked for common proper motion by comparing 2MASS to GAIA DR1 positions and a rather surprisingly large part of the objects qualify indeed as potential CPM pairs. For a few objects also WDS position errors were found.

  2. A Green Platform for Preparation of the Well-Defined Polyacrylonitrile: 60Co γ-ray Irradiation-Initiated RAFT Polymerization at Room Temperature

    Directory of Open Access Journals (Sweden)

    Shuangshuang Zhang


    Full Text Available 60Co γ-ray irradiation-initiated reversible addition–fragmentation chain transfer (RAFT polymerization at room temperature with 2-cyanoprop-2-yl 1-dithionaphthalate (CPDN as the chain transfer agent was first applied to acrylonitrile (AN polymerization, providing a “green” platform for preparing polyacrylonitrile (PAN-based carbon fibers using an environment-friendly energy source. Various effects of dose rate, molar ratio of the monomer to the chain transfer agent, monomer concentration and reaction time on the AN polymerization behaviors were performed to improve the controllability of molecular the weight and molecular weight distribution of the obtained PAN. The feature of the controlled polymerization was proven by the first-order kinetics, linear increase of the molecular weight with the monomer conversion and a successful chain-extension experiment. The molecular weight and molecular weight distribution of PAN were characterized by size exclusion chromatography (SEC. 1H NMR and Matrix assisted laser desorption ionization/time of flight mass spectra (MALDI-TOF-MS confirmed the chain-end functionality of PAN, which also was supported by the successful chain-extension experiments of original PANs with acrylonitrile and styrene as the second monomers respectively.

  3. Bioanalytical chromatographic method validation according to current regulations, with a special focus on the non-well defined parameters limit of quantification, robustness and matrix effect. (United States)

    González, Oskar; Blanco, María Encarnación; Iriarte, Gorka; Bartolomé, Luis; Maguregui, Miren Itxaso; Alonso, Rosa M


    Method validation is a mandatory step in bioanalysis, to evaluate the ability of developed methods in providing reliable results for their routine application. Even if some organisations have developed guidelines to define the different parameters to be included in method validation (FDA, EMA); there are still some ambiguous concepts in validation criteria and methodology that need to be clarified. The methodology to calculate fundamental parameters such as the limit of quantification has been defined in several ways without reaching a harmonised definition, which can lead to very different values depending on the applied criterion. Other parameters such as robustness or ruggedness are usually omitted and when defined there is not an established approach to evaluate them. Especially significant is the case of the matrix effect evaluation which is one of the most critical points to be studied in LC-MS methods but has been traditionally overlooked. Due to the increasing importance of bioanalysis this scenario is no longer acceptable and harmonised criteria involving all the concerned parties should be arisen. The objective of this review is thus to discuss and highlight several essential aspects of method validation, focused in bioanalysis. The overall validation process including common validation parameters (selectivity, linearity range, precision, accuracy, stability…) will be reviewed. Furthermore, the most controversial parameters (limit of quantification, robustness and matrix effect) will be carefully studied and the definitions and methodology proposed by the different regulatory bodies will be compared. This review aims to clarify the methodology to be followed in bioanalytical method validation, facilitating this time consuming step. Copyright © 2014 Elsevier B.V. All rights reserved.

  4. Distribution of MEG and methanol in well-defined hydrocarbon and water systems: Experimental measurement and modeling using the CPA EoS

    DEFF Research Database (Denmark)

    Riaz, Muhammad; Yussuf, Mustafe A.; Kontogeorgis, Georgios


    Liquid-liquid equilibria data for two binary and two ternary systems are reported in the temperature range of 303.15-323.15. K at atmospheric pressure. The binary systems measured are n-nonane + MEG and ethylbenzene + MEG and the ternary systems are n-nonane + MEG + water and ethylbenzene + MEG...... + water. These data are satisfactorily correlated (binaries) and predicted (ternaries) using Cubic Plus Association (CPA) equation of state (EoS). CPA is also applied to binary LLE of aromatic hydrocarbon + water and VLE of methane + methanol. Finally the distribution of water and inhibitors (methanol...... and MEG) in various phases is modeled using CPA. The hydrocarbon phase consists of mixture-1 (methane, ethane, n-butane) or mixture-2 (methane, ethane, propane, n-butane, n-heptane, toluene and n-decane). CPA can satisfactorily predict the water content in the gas phase of the multicomponent systems...

  5. Development of a self-supported single-wall carbon nanotube-based gas diffusion electrode with spatially well-defined reaction and diffusion layers (United States)

    Drillet, J.-F.; Bueb, H.; Dettlaff-Weglikowska, U.; Dittmeyer, R.; Roth, S.

    This work reports on the development of a solvent-free method for the fabrication of a self-supported single-wall carbon nanotubes electrode, which is based on successive sedimentation of both SWCNT/surfactant and PtRu-SWCNT/surfactant suspensions followed by a thermal treatment at 130 °C. The as-prepared self-supported electrode showed sufficient mechanical strength for half-cell investigation and membrane-electrodes assembly fabrication. By using a Pt catalyst loading of 1 mg cm -2, the overall thickness of the gas diffusion electrode reached 95 μm. Its electrochemical activity towards methanol oxidation was investigated by means of cyclic voltammetry and current-voltage polarisation measurements under half-cell and direct methanol fuel cell conditions.

  6. Development of a self-supported single-wall carbon nanotube-based gas diffusion electrode with spatially well-defined reaction and diffusion layers

    Energy Technology Data Exchange (ETDEWEB)

    Drillet, J.-F.; Bueb, H.; Dittmeyer, R. [DECHEMA e.V., Society for Chemical Engineering and Biotechnology, Karl Winnacker Institute, Theodor-Heuss-Allee 25, 60486 Frankfurt am Main (Germany); Dettlaff-Weglikowska, U.; Roth, S. [Max Planck Institute for Solid State Research, Heisenbergstrasse 1, 70569 Stuttgart (Germany)


    This work reports on the development of a solvent-free method for the fabrication of a self-supported single-wall carbon nanotubes electrode, which is based on successive sedimentation of both SWCNT/surfactant and PtRu-SWCNT/surfactant suspensions followed by a thermal treatment at 130 C. The as-prepared self-supported electrode showed sufficient mechanical strength for half-cell investigation and membrane-electrodes assembly fabrication. By using a Pt catalyst loading of 1 mg cm{sup -2}, the overall thickness of the gas diffusion electrode reached 95 {mu}m. Its electrochemical activity towards methanol oxidation was investigated by means of cyclic voltammetry and current-voltage polarisation measurements under half-cell and direct methanol fuel cell conditions. (author)

  7. Well-defined polyethylene-based graft terpolymers by combining nitroxide-mediated radical polymerization, polyhomologation and azide/alkyne “click” chemistry†

    KAUST Repository

    Alkayal, Nazeeha


    Novel well–defined polyethylene–based graft terpolymers were synthesized via the “grafting onto” strategy by combining nitroxide-mediated radical polymerization (NMP), polyhomologation and copper (I)-catalyzed azide-alkyne cycloaddition (CuAAC) “click” chemistry. Three steps were involved in this approach: (i) synthesis of alkyne-terminated polyethylene-b-poly(ε-caprolactone) (PE-b-PCL-alkyne) block copolymers (branches) by esterification of PE-b-PCL-OH with 4-pentynoic acid; the PE-b-PCL-OH was obtained by polyhomologation of dimethylsulfoxonium methylide to afford PE-OH, followed by ring opening polymerization of ε-caprolactone using the PE-OH as macroinitiator, (ii) synthesis of random copolymers of styrene (St) and 4-chloromethylstyrene (4-CMS) with various CMS contents, by nitroxide-mediated radical copolymerization (NMP), and conversion of chloride to azide groups by reaction with sodium azide (NaN3) (backbone) and (iii) “click” linking reaction to afford the PE-based graft terpolymers. All intermediates and final products were characterized by high-temperature size exclusion chromatography (HT-SEC), Fourier transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance spectroscopy (1H NMR) and differential scanning calorimetry (DSC).

  8. Microscope-assisted UV-initiated preparation of well-defined porous polymer monolithic plugs in glass microchips for peptide preconcentration. (United States)

    Dziomba, Szymon; Araya-Farias, Monica; Taverna, Myriam; Guerrouache, Mohamed; Carbonnier, Benjamin; Tran, N Thuy


    Herein, highly defined monolithic beds were prepared in glass microchips by photopolymerization of ethylene glycol methacrylate phosphate (EGMP), acrylamide, and N,N'-methylenebisacrylamide (BAA) using an epifluorescence microscope as UV-irradiation source. Such a fast and easy method allowed precise control of (i) the edge shape, (ii) the location along the microchannel, and (iii) the length of the monolithic plugs within glass microchips. The addition of hydroquinone, a polymerization inhibitor, to the prepolymerization mixture was beneficial for achieving local and robust incorporation of monoliths with sharp edges within microchannels. The monolith length was easily tuned from 160 to 400 μm through simple change in the magnification of the objective and was found to be repeatable (relative standard deviation microscope-UV-synthesis of monolithic plugs with sharp edges.


    The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

  10. The Candy Man Can; How well-defined brands and critical strategic thinking helped Dan Alvo drive local relevance for Wrigley's brands amid global budget pressure

    National Research Council Canada - National Science Library

    Josh Kolm


      Heading into 2016, Wrigley Canada was in a tough position. There was pressure from the confectionary company's global HQ to build candy and mint brands when it was already dealing with a declining gum category, its largest business...

  11. Covalent surface immobilization of Arg-Gly-Asp- and Tyr-Ile-Gly-Ser-Arg-containing peptides to obtain well-defined cell-adhesive substrates. (United States)

    Massia, S P; Hubbell, J A


    The synthetic peptides Gly-Arg-Gly-Asp-Tyr and Gly-Tyr-Ile-Gly-Ser-Arg-Tyr, which contain Arg-Gly-Asp (RGD) and Tyr-Ile-Gly-Ser-Arg (YIGSR), the ligands for two important classes of cell adhesion receptors, were covalently coupled to a nonadhesive modified glass surface by the N-terminal Gly. The N-terminal Gly served as a spacer, and the C-terminal Y served as a site for radioiodination. These modified substrates supported the adhesion and spreading of cultured human foreskin fibroblasts (HFFs) independently of adsorbed proteins and, it was demonstrated that a covalently immobilized YIGSR-containing peptide has biological activity. The surface concentration of grafted peptide on the glass was measured by 125I radio-labeling and was 12.1 pmol/cm2. HFFs spread on both immobilized peptide substrates, but at much slower rates on grafted YIGSR glass surfaces than on the RGD-containing substrates. Cells formed focal contacts on the RGD-derivatized substrates in the presence or absence of serum. Focal contacts formed on the YIGSR-grafted surfaces only when serum was present in the medium and had morphologies different from those observed on the RGD-containing substrates. Serum influenced the organization of microfilaments and the extent of spreading of adherent cells, although adsorption of adhesion proteins was minimal on all substrates. This derivatization method produced chemically stable substrates which may be useful in studying receptor-mediated cell adhesion, as the quantity of peptide available at the surface may be precisely measured and controlled.

  12. An Undergraduate Chemistry Laboratory: Synthesis of Well-Defined Polymers by Low-Catalyst-Concentration ATRP and Postpolymerization Modification to Fluorescent Materials (United States)

    Tsarevsky, Nicolay V.; Woodruf, Shannon R.; Wisian-Neilson, Patty J.


    A two-session experiment is designed to introduce undergraduate students to concepts in catalysis, transition metal complexes, polymer synthesis, and postpolymerization modifications. In the first session, students synthesize poly(glycidyl methacrylate) via low-catalyst-concentration atom transfer radical polymerization (ATRP). The…

  13. Controlled interactions between anhydrous keggin-type heteropolyacids and silica support: Preparation and characterization of well-defined silica-supported polyoxometalate species

    KAUST Repository

    Grinenval, Eva


    Anhydrous Keggin-type phosphorus heteropolyacids were deposited on partially dehydroxylated silica by using the surface organometallic chemistry (SOMC) strategy. The resulting solids were characterized by a combination of physicochemical methods including IR, Raman, 1D and 2D 1H, and 31P MAS NMR, electron microscopy experiments and density functional theory (DFT) calculations. It is shown that the main surface species is [ - Si(OH...H+)]2[H+]1[PM 12O403-] where the polyoxometalate is linked to the support by proton interaction with two silanols. Two other minor species (10% each) are formed by coordination of the polyoxometalate to the surface via the interaction between all three protons with three silanol groups or via three covalent bonds formed by dehydroxylation of the above species. Comparison of the reactivity of these solids and of compounds prepared by a classical way shows that the samples prepared by the SOMC approach contain ca. 7 times more acid sites. © 2010 American Chemical Society.

  14. Cystinosin, MPDU1, SWEETs and KDELR belong to a well-defined protein family with putative function of cargo receptors involved in vesicle trafficking. (United States)

    Saudek, Vladimir


    Classification of proteins into families based on remote homology often helps prediction of their biological function. Here we describe prediction of protein cargo receptors involved in vesicle formation and protein trafficking. Hidden Markov model profile-to-profile searches in protein databases using endoplasmic reticulum lumen protein retaining receptors (KDEL, Erd2) as query reveal a large and diverse family of proteins with seven transmembrane helices and common topology and, most likely, similar function. Their coding genes exist in all eukaryota and in several prokaryota. Some are responsible for metabolic diseases (cystinosis, congenital disorder of glycosylation), others are candidate genes for genetic disorders (cleft lip and palate, certain forms of cancer) or solute uptake and efflux (SWEETs) and many have not yet been assigned a function. Comparison with the properties of KDEL receptors suggests that the family members could be involved in protein trafficking and serve as cargo receptors. This prediction sheds new light on a range of biologically, medically and agronomically important proteins and could open the way to discovering the function of many genes not yet annotated. Experimental testing is suggested.

  15. First line treatment response in patients with transmitted HIV drug resistance and well defined time point of HIV infection: updated results from the German HIV-1 seroconverter study. (United States)

    Zu Knyphausen, Fabia; Scheufele, Ramona; Kücherer, Claudia; Jansen, Klaus; Somogyi, Sybille; Dupke, Stephan; Jessen, Heiko; Schürmann, Dirk; Hamouda, Osamah; Meixenberger, Karolin; Bartmeyer, Barbara


    Transmission of drug-resistant HIV-1 (TDR) can impair the virologic response to antiretroviral combination therapy. Aim of the study was to assess the impact of TDR on treatment success of resistance test-guided first-line therapy in the German HIV-1 Seroconverter Cohort for patients infected with HIV between 1996 and 2010. An update of the prevalence of TDR and trend over time was performed. Data of 1,667 HIV-infected individuals who seroconverted between 1996 and 2010 were analysed. The WHO drug resistance mutations list was used to identify resistance-associated HIV mutations in drug-naïve patients for epidemiological analysis. For treatment success analysis the Stanford algorithm was used to classify a subset of 323 drug-naïve genotyped patients who received a first-line cART into three resistance groups: patients without TDR, patients with TDR and fully active cART and patients with TDR and non-fully active cART. The frequency of virologic failure 5 to 12 months after treatment initiation was determined. Prevalence of TDR was stable at a high mean level of 11.9% (198/1,667) in the HIV-1 Seroconverter Cohort without significant trend over time. Nucleotide reverse transcriptase inhibitor resistance was predominant (6.0%) and decreased significantly over time (OR = 0.92, CI = 0.87-0.98, p = 0.01). Non-nucleoside reverse transcriptase inhibitor (2.4%; OR = 1.00, CI = 0.92-1.09, p = 0.96) and protease inhibitor resistance (2.0%; OR = 0.94, CI = 0.861.03, p = 0.17) remained stable. Virologic failure was observed in 6.5% of patients with TDR receiving fully active cART, 5,6% of patients with TDR receiving non-fully active cART and 3.2% of patients without TDR. The difference between the three groups was not significant (p = 0.41). Overall prevalence of TDR remained stable at a rather high level. No significant differences in the frequency of virologic failure were identified during first-line cART between patients with TDR and fully-active cART, patients with TDR and non-fully active cART and patients without TDR.

  16. First line treatment response in patients with transmitted HIV drug resistance and well defined time point of HIV infection: updated results from the German HIV-1 seroconverter study.

    Directory of Open Access Journals (Sweden)

    Fabia Zu Knyphausen

    Full Text Available BACKGROUND: Transmission of drug-resistant HIV-1 (TDR can impair the virologic response to antiretroviral combination therapy. Aim of the study was to assess the impact of TDR on treatment success of resistance test-guided first-line therapy in the German HIV-1 Seroconverter Cohort for patients infected with HIV between 1996 and 2010. An update of the prevalence of TDR and trend over time was performed. METHODS: Data of 1,667 HIV-infected individuals who seroconverted between 1996 and 2010 were analysed. The WHO drug resistance mutations list was used to identify resistance-associated HIV mutations in drug-naïve patients for epidemiological analysis. For treatment success analysis the Stanford algorithm was used to classify a subset of 323 drug-naïve genotyped patients who received a first-line cART into three resistance groups: patients without TDR, patients with TDR and fully active cART and patients with TDR and non-fully active cART. The frequency of virologic failure 5 to 12 months after treatment initiation was determined. RESULTS: Prevalence of TDR was stable at a high mean level of 11.9% (198/1,667 in the HIV-1 Seroconverter Cohort without significant trend over time. Nucleotide reverse transcriptase inhibitor resistance was predominant (6.0% and decreased significantly over time (OR = 0.92, CI = 0.87-0.98, p = 0.01. Non-nucleoside reverse transcriptase inhibitor (2.4%; OR = 1.00, CI = 0.92-1.09, p = 0.96 and protease inhibitor resistance (2.0%; OR = 0.94, CI = 0.861.03, p = 0.17 remained stable. Virologic failure was observed in 6.5% of patients with TDR receiving fully active cART, 5,6% of patients with TDR receiving non-fully active cART and 3.2% of patients without TDR. The difference between the three groups was not significant (p = 0.41. CONCLUSION: Overall prevalence of TDR remained stable at a rather high level. No significant differences in the frequency of virologic failure were identified during first-line cART between patients with TDR and fully-active cART, patients with TDR and non-fully active cART and patients without TDR.

  17. The Autism Diagnostic Observation Schedule, Module 4: Application of the Revised Algorithms in an Independent, Well-Defined, Dutch Sample (N = 93) (United States)

    de Bildt, Annelies; Sytema, Sjoerd; Meffert, Harma; Bastiaansen, Jojanneke A. C. J.


    This study examined the discriminative ability of the revised Autism Diagnostic Observation Schedule module 4 algorithm (Hus and Lord in "J Autism Dev Disord" 44(8):1996-2012, 2014) in 93 Dutch males with Autism Spectrum Disorder (ASD), schizophrenia, psychopathy or controls. Discriminative ability of the revised algorithm ASD cut-off…

  18. New data on morphometrics, distribution and ecology of Mioscirtus wagneri (Kittary, 1849 (Orthoptera, Acrididae in Spain: is maghrebi a well defined subespecies?

    Directory of Open Access Journals (Sweden)

    Aparicio, J. M.


    Full Text Available We studied different populations of Mioscirtus wagneri (Kittary, 1859 in Spain assigned to subspecies maghrebi by Fernandes (1968 and obtained some new records for the species. To see if maghrebi is a consistent taxon for the Iberian populations, we performed a morphometric analysis involving 53 individuals from different origins considering body size (front of the head to tip of the abdomen; the shape of pronotum and presence of a second anterior notch or sulcus; length of the antennae and epiphallum, according to the characters used to define subspecies maghrebi. If maghrebi is consistent, we would expect intermediate sizes between wagneri and rogenhoferi, the other two well separated subspecies considered for M.w. However, in our measurements we obtained that body size is not intermediate between M. w. wagneri and M. w. rogenhoferi contrary to expectations if assuming the existence of maghrebi. Body size is similar to wagneri and further, we recorded some of the smallest individuals described so far. Also, the pronotum varied widely across and within populations showing different phenotypes that formerly were used to separate maghrebi and wagneri. Taking into account body size, pronotum, length of antenna and epiphallum, we think that differences between the studied Spanish populations and wagneri form are not enough to assign the studied populations to maghrebi. In the studied area, M.w. shows a narrow ecological niche inhabiting shores or proximities of hipersaline lagoons wherever Suaeda vera (Forsskål 1791, Chenopodiacea is present, M.w. uses this plant as refuge and food. The species also inhabits bare saline low grounds with scattered S vera. It presents a markedly discontinuous and patchy distribution in Spain, showing up punctually, where the microhabitat is appropriate. We obtained a morphometric variability with a significant association between body size and locality, and between body size and the colour of posterior wings in males. Because of its wide range disjunction, its discontinuous regional distribution and morphological variability, we believe that M.w. is an interesting species to investigate possible substructuring of populations in which we probably may recognize ecological forms or varieties that deserve deeper and further study.Estudiamos distintas poblaciones de Mioscirtus wagneri (Kittary, 1859, considerado como M. w. maghrebi por Fernandes (1968 en España, con algunas nuevas citas para la especie. Para dilucidar si el taxón maghrebi es consistente en nuestras poblaciones, realizamos un análisis morfométrico de 53 ejemplares considerando los mismos caracteres utilizados para establecer dicha subespecie, a citar: tamaño del cuerpo, relieve y forma del pronoto, longitud de la antena y forma del epifalo. El tamaño de los individuos de nuestras poblaciones no es intermedio entre las formas conocidas de M. w. wagneri y M. w. rogenhoferi Saussuare, 1888, como cabría esperar asumiendo la existencia de maghrebi. Nuestras poblaciones no se apartan del tamaño de wagneri e incluso encontramos las menores tallas descritas para este taxón. El relieve del pronoto, y en particular la presencia de un segundo surco, el anterior, es muy variable abarcando en una misma población fenotipos dispares utilizados anteriormente para separar las formas maghrebi y wagneri. Las diferencias entre el tamaño del cuerpo, el pronoto, la longitud de la antena y la forma del epifalo no nos parecen suficientes para asignar como maghrebi al conjunto de las poblaciones estudiadas y separarlas de la subespecie nominada wagneri. M.w. es una especie de requerimientos ecológicos muy restringidos. La hemos encontrado a orillas de lagunas hipersalinas y siempre dependiendo de Suaeda vera (Forsskål, 1791 Chenopodiacea que utiliza como refugio y alimento, en particular en suelos desnudos y salitrosos donde predominan manchas de esa planta. Su distribución regional es marcadamente discontinua y muy puntual, presentándose allí donde el hábitat le es propicio. Aunque el análisis es preliminar, encontramos una variabilidad morfométrica y una asociación del tamaño corporal con la localidad, y del tamaño corporal con la coloración de las alas posteriores en los machos. Debido a su distribución geográfica disjunta, localmente discontinua, y a la variabilidad morfométrica encontrada en sus poblaciones, creemos que M. w. es una especie interesante para investigar la posible subestructuración de sus poblaciones en las cuales es posible se reconozcan diversas formas o variedades ecológicas lo que merece mayor investigación.

  19. One-pot synthesis of well-defined polyether/polyester block copolymers and terpolymers by a highly efficient catalyst switch approach

    KAUST Repository

    Alamri, Haleema


    A highly efficient methodology, based on a novel catalyst switch approach with rapid crossover characteristics, was developed for the one-pot synthesis of block co/terpolymers of cyclic ethers and esters. This new approach, which takes advantage of one of the best catalysts for epoxide (t-BuP4) and cyclic ester (t-BuP2) polymerization, opens new horizons toward the synthesis of cyclic ether/ester complex macromolecular architectures. © The Royal Society of Chemistry 2016.

  20. Long-term changes in bone mass after partial gastrectomy in a well-defined population and its relation to tobacco and alcohol consumption

    DEFF Research Database (Denmark)

    Krogsgaard, M R; Frølich, A; Lund, B


    alcohol consumption or cumulative tobacco consumption and bone mineral content in each group. Gastrectomized women smoked much more than control women, and smoking may be a determinant factor for the bone loss, as it is in healthy persons. Operated patients had a lower intake of milk products. All...... patients were exposed to sunlight for more than 3 hours/week. It is suggested that osteopenia after gastrectomy might be caused by calcium depletion rather than lack of vitamin D. The consumption of tobacco but not of alcohol was connected to bone loss....

  1. Well-defined functional mesoporous silica/polymer hybrids prepared by an ICAR ATRP technique integrated with bio-inspired polydopamine chemistry for lithium isotope separation. (United States)

    Liu, Yuekun; Liu, Xuegang; Ye, Gang; Song, Yang; Liu, Fei; Huo, Xiaomei; Chen, Jing


    Mesoporous silica/polymer hybrids with well-preserved mesoporosity were prepared by integrating the initiators for continuous activator regeneration (ICAR) atom transfer radical polymerization (ATRP) technique with the bio-inspired polydopamine (PDA) chemistry. By manipulating the auto-oxidative polymerization of dopamine, uniform PDA layers were deposited on the surfaces and pore walls of ordered mesoporous silicas (OMSs), thereby promoting the immobilization of ATRP initiators. Poly(glycidyl methacrylate) (PGMA) brushes were then grown from the OMSs by using the ICAR ATRP technique. The evolution of the mesoporous silica/polymer hybrids during synthesis, in terms of morphology, structure, surface and porous properties, was detailed. And, parameters influencing the controlled growth of polymer chains in the ICAR ATRP system were studied. Taking advantage of the abundant epoxy groups in the PGMA platform, post-functionalization of the mesoporous silica/polymer hybrids by the covalent attachment of macrocyclic ligands for the adsorptive separation of lithium isotopes was realized. Adsorption behavior of the functionalized hybrids toward lithium ions was fully investigated, highlighting the good selectivity, and effects of temperature, solvent and counter ions. The ability for lithium isotope separation was evaluated. A higher separation factor could be obtained in systems with softer counter anions and lower polarity solvents. More importantly, due to the versatility of the ICAR ATRP technique, combined with the non-surface specific PDA chemistry, the methodology established in this work would provide new opportunities for the preparation of advanced organic-inorganic porous hybrids for broadened applications.

  2. Breast cancer in situ. From pre-malignant lesion of uncertain significance to well-defined non-invasive malignant lesion

    DEFF Research Database (Denmark)

    Laenkholm, Anne-Vibeke; Jensen, Maj-Britt; Kroman, Niels


    In addition to nationwide standardized pathology forms for operable primary invasive breast cancer, the Danish Breast Cancer cooperative Group (DBCG) in 1982 introduced pathology forms for breast cancer in situ (CIS). The histological reporting form was used primarily for ductal cancer in situ...... receptor (ER) and Progesteron receptor (PR) status. Also mastectomy specimens were included. In 2004 the previous malignancy grading was replaced by the Van Nuys classification, and information on microcalcifications was introduced. The axillary status now included the sentinel node technique only. In 2006...

  3. Selective Hydrogen Generation from Formic Acid with Well-Defined Complexes of Ruthenium and Phosphorus-Nitrogen PN3-Pincer Ligand

    KAUST Repository

    Pan, Yupeng


    An unsymmetrically protonated PN3-pincer complex in which ruthenium is coordinated by one nitrogen and two phosphorus atoms was employed for the selective generation of hydrogen from formic acid. Mechanistic studies suggest that the imine arm participates in the formic acid activation/deprotonation step. A long life time of 150 h with a turnover number over 1 million was achieved. Grabbing hold: A PN3-pincer complex was employed for the selective hydrogen generation from formic acid. Mechanistic studies suggest the imine arm participates in the formic acid activation/deprotonation step. A long life time of 150 h with a turnover number over 1 million was achieved. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Synthesis of Well-Defined, Water-Soluble Hyperbranched Polyamides by Chain-Growth Condensation Polymerization of AB2 Monomer

    Directory of Open Access Journals (Sweden)

    Akihiro Yokoyama


    Full Text Available Condensation polymerization of 5-aminoisophthalic acid methyl ester 1 bearing a N-tri(ethylene glycol methyl ester (TEG chain as an AB2 monomer was conducted and the properties of the resulting hyperbranched polyamides (HBPA were investigated. When the polymerization of 1 was carried out with N-methyl core initiator 2b at various feed ratios of 1 to 2b ([1]0/[2b]0 in the presence of LiHMDS and LiCl at −10 °C, the Mn values of the obtained HBPA increased in proportion to the [1]0/[2b]0 ratio from 7 to 46 (Mn = 3810–18600, retaining a narrow molecular weight distribution (Mw/Mn = 1.11–1.19. The HBPA was soluble in water, and a 0.25 wt.−% aqueous solution of the HBPA exhibited a lower critical solution temperature (LCST. The cloud point was 21–23 °C, which is about 30 °C lower than that of the corresponding poly(m-benzamide with the N-TEG unit.

  5. Linking an Anxiety-Related Personality Trait to Cardiac Autonomic Regulation in Well-Defined Healthy Adults: Harm Avoidance and Resting Heart Rate Variability. (United States)

    Kao, Lien-Cheng; Liu, Yu-Wen; Tzeng, Nian-Sheng; Kuo, Terry B J; Huang, San-Yuan; Chang, Chuan-Chia; Chang, Hsin-An


    Anxiety trait, anxiety and depression states have all been reported to increase risks for cardiovascular disease (CVD), possibly through altering cardiac autonomic regulation. Our aim was to investigate whether the relationship between harm avoidance (HA, an anxiety-related personality trait) and cardiac autonomic regulation is independent of anxiety and depression states in healthy adults. We recruited 535 physically and mentally healthy volunteers. Participants completed the Beck Anxiety Inventory (BAI), Beck Depression Inventory (BDI) and Tri-dimensional Personality Questionnaire. Participants were divided into high or low HA groups as discriminated by the quartile value. Cardiac autonomic function was evaluated by measuring heart rate variability (HRV). We obtained the time and frequency-domain indices of HRV including variance (total HRV), the low-frequency power (LF; 0.05-0.15 Hz), which may reflect baroreflex function, the high-frequency power (HF; 0.15-0.40 Hz), which reflects cardiac parasympathetic activity, as well as the LF/HF ratio. The BDI and HA scores showed associations with HRV parameters. After adjustment for the BDI scores and other control variables, HA is still associated with reduced variance, LF and HF power. Compared with the participants with low HA, those with high HA displayed significant reductions in variance, LF and HF power and a significant increase in their LF/HF ratio. This study highlights the independent role of HA in contributing to decreased autonomic cardiac regulation in healthy adults and provides a potential underlying mechanism for anxiety trait to confer increased risk for CVD.

  6. Facile Synthesis of Well-Defined MDMO-PPV Containing (Tri)Block-Copolymers via Controlled Radical Polymerization and CuAAC Conjugation


    ZAQUEN, Neomy; VANDENBERGH, Joke; Schneider-Baumann, Maria; LUTSEN, Laurence; VANDERZANDE, Dirk; JUNKERS, Thomas


    A systematic investigation into the chain transfer polymerization of the so-called radical precursor polymerization of poly(p-phenylene vinylene) (PPV) materials is presented. Polymerizations are characterized by systematic variation of chain transfer agent (CTA) concentration and reaction temperature. For the chain transfer constant, a negative activation energy of -12.8 kJ center dot mol(-1) was deduced. Good control over molecular weight is achieved for both the sulfinyl and the dithiocarb...

  7. Facile Synthesis of Well-Defined MDMO-PPV Containing (TriBlock—Copolymers via Controlled Radical Polymerization and CuAAC Conjugation

    Directory of Open Access Journals (Sweden)

    Neomy Zaquen


    Full Text Available A systematic investigation into the chain transfer polymerization of the so-called radical precursor polymerization of poly(p-phenylene vinylene (PPV materials is presented. Polymerizations are characterized by systematic variation of chain transfer agent (CTA concentration and reaction temperature. For the chain transfer constant, a negative activation energy of −12.8 kJ·mol−1 was deduced. Good control over molecular weight is achieved for both the sulfinyl and the dithiocarbamate route (DTC. PPVs with molecular weights ranging from thousands to ten thousands g·mol−1 were obtained. To allow for a meaningful analysis of the CTA influence, Mark–Houwink–Kuhn–Sakurada (MHKS parameters were determined for conjugated MDMO-PPV ([2-methoxy-5-(3',7'-dimethyloctyloxy]-1,4-phenylenevinylene to α = 0.809 and k = 0.00002 mL·g−1. Further, high-endgroup fidelity of the CBr4-derived PPVs was proven via chain extension experiments. MDMO-PPV-Br was successfully used as macroinitiator in atom transfer radical polymerization (ATRP with acrylates and styrene. A more polar PPV counterpart was chain extended by an acrylate in single-electron transfer living radical polymerization (SET-LRP. In a last step, copper-catalyzed azide alkyne cycloaddition (CuAAC was used to synthesize block copolymer structures. Direct azidation followed by macromolecular conjugation showed only partial success, while the successive chain extension via ATRP followed by CuAAC afforded triblock copolymers of the poly(p-phenylene vinylene-block-poly(tert-butyl acrylate-block-poly(ethylene glycol (PPV-b-PtBuA-b-PEG.

  8. Electron exchange between r-keggin tungstoaluminates and a well-defined cluster-anion probe for studies in electron transfer (United States)

    Yurii V. Geletii; Craig L. Hill; Alan J. Bailey; Kenneth I. Hardcastle; Rajai H. Atalla; Ira A. Weinstock


    Fully oxidized [alpha]-AlIIIW12O405-(1ox), and one-electron-reduced [alpha]-AlIIIW12O406-(1red), are well-behaved (stable and free of ion pairing) over a wide range of pH and ionic-strength values at room temperature in water. Having established this, 27Al NMR spectroscopy is used to measure rates of electron exchange between 1ox (27Al NMR: 72.2 ppm relative to Al(H2O)...

  9. Selective Catalytic Hydrogenation of Arenols by a Well-Defined Complex of Ruthenium and Phosphorus–Nitrogen PN3–Pincer Ligand Containing a Phenanthroline Backbone

    KAUST Repository

    Li, Huaifeng


    Selective catalytic hydrogenation of aromatic compounds is extremely challenging using transition-metal catalysts. Hydrogenation of arenols to substituted tetrahydronaphthols or cyclohexanols has been reported only with heterogeneous catalysts. Herein, we demonstrate the selective hydrogenation of arenols to the corresponding tetrahydronaphthols or cyclohexanols catalyzed by a phenanthroline-based PN3-ruthenium pincer catalyst.

  10. Synthesis of PVDF Homo- and Co-Polymers with Well-Defined Molecular Structure; Using Borane/Oxygen Coordination Free Radical Initiator

    National Research Council Canada - National Science Library

    Chung, T


    ...) The terpolymers exhibit excellent electric properties. Comparing with the known VDF/TrFE copolymer, the slightly bulky chlorine atoms randomly distributed along the polymer chain spontaneously alter the crystalline phase from Beta-phase...

  11. Mesoporous Bragg reflectors: block-copolymer self-assembly leads to building blocks with well defined continuous pores and high control over optical properties

    KAUST Repository

    Guldin, S.


    Mesoporous distributed Bragg re ectors (MDBRs) exhibit porosity on the sub-optical length scale. This makes them ideally suited as sensing platforms in biology and chemistry as well as for light management in optoelectronic devices. Here we present a new fast forward route for the fabrication of MDBRs which relies on the self-assembling properties of the block copolymer poly(isoprene-block -ethylene oxide) (PI-b -PEO) in combination with sol-gel chemistry. The interplay between structure directing organic host and co-assembled inorganic guest allows the ne tuning of refractive index in the outcome material. The refractive index dierence between the high and low porosity layer can be as high as 0.4, with the optical interfaces being well dened. Following a 30 min annealing protocol after each layer deposition enables the fast and reliable stacking of MDBRs which exhibit a continuous TiO2 network with large accessible pores and high optical quality.

  12. The Clinical, Symptom, and Quality-of-Life Characterization of a Well-Defined Group of Patients with Posttreatment Lyme Disease Syndrome

    Directory of Open Access Journals (Sweden)

    Alison W. Rebman


    Full Text Available BackgroundThe increased incidence and geographic expansion of Lyme disease has made it the most common vector-borne infection in North America. Posttreatment Lyme disease syndrome (PTLDS represents a subset of patients who remain ill following standard antibiotic therapy for Lyme disease. The spectrum of symptoms and their impact on quality of life remain largely unexplored among patients with well-documented PTLDS.ObjectiveTo characterize a case series of patients with well-documented PTLDS compared to a sample of healthy controls.MethodsSixty-one participants met the proposed case definition for PTLDS. Twenty-six healthy controls had neither a clinical history of Lyme disease nor current antibodies to Borrelia burgdorferi. Participants with PTLDS and controls were evaluated by physical exam, clinical laboratory testing, standardized questionnaires, and a 36-item current symptom list.ResultsCompared to controls, participants with PTLDS reported significantly greater fatigue, pain, sleep disturbance, and depression (Fatigue Severity Scale: 50.0 ± 10.6 vs. 19.8 ± 8.6; Short-Form McGill Pain Questionnaire: 13.7 ± 8.3 vs. 0.8 ± 1.9; Pittsburgh Sleep Quality Index: 10.1 ± 4.7 vs. 4.1 ± 2.1; Beck Depression Inventory-II: 15.1 ± 7.7 vs. 2.2 ± 3.2; p < 0.001 for each, and significantly lower quality of life (SF-36 Physical Component Score: 33.9 ± 9.7 vs. 55.1 ± 6.2; Mental Component Score: 42.9 ± 10.1 vs. 54.2 ± 5.4; p < 0.001 for each. Nineteen non-PTLDS-defining symptoms were found to be significantly more severe among participants with PTLDS than controls, including sleep difficultly and visual complaints. Initial delayed or misdiagnosis was characterized in 59.0% of participants with PTLDS, and 32.2% had abnormal vibratory sense.ConclusionAlthough physical exam and clinical laboratory tests showed few objective abnormalities, standardized symptom questionnaires revealed that patients with PTLDS are highly and clinically significantly symptomatic, with poor health-related quality of life. PTLDS patients exhibited levels of fatigue, musculoskeletal pain, sleep disturbance, and depression which were both clinically relevant and statistically significantly higher than controls. Our study shows that PTLDS can be successfully identified using a systematic approach to diagnosis and symptom measurement. As the prevalence of PTLDS continues to rise, there will be an increased need for physician education to more effectively identify and manage PTLDS as part of integrated patient care.

  13. DOuble LOngitudinal Megapreputium Incision TEchnique: the DOLOMITE. (United States)

    Callewaert, Piet R H; Rahnama'i, Mohammad S; Guimarães, Maia N C; Vrijens, Daisy M J; Van Kerrebroeck, Philip E V A


    To present a straightforward, reproducible technique with the basic principle of preserving all available outer penile shaft skin and using this to cover the dorsal side of the penis. The DOuble LOngitudinal Megapreputium Incision TEchnique is presented in a step-by-step fashion. Six consecutive patients with a mean age of 13.3 months (range, 7-25) underwent this reconstruction between 2006 and 2011. The technique starts with 2 longitudinal incisions, the first on the ventral side, and the second on the dorsal side of the penis. After hinging the penile skin to the dorsal side, redundant inner preputial tissue is resected using diagonal incisions. Dartos is spared. A comparison with previously reported techniques and a concise review of existing literature are provided. The final cosmetic results, after an initial period of edematous swelling of the ventral aspect of the penis, were good in all patients. The bilateral diagonal scars on the penile shaft became inconspicuous over time. Voiding normalized. No complications occurred. The DOuble LOngitudinal Megapreputium Incision TEchnique provides a straightforward and reproducible surgical correction for congenital megaprepuce. Copyright © 2014 Elsevier Inc. All rights reserved.

  14. Cutaneous presentation of Double Hit Lymphoma

    Directory of Open Access Journals (Sweden)

    Yousef Khelfa MD, FACP


    Full Text Available Diffuse large B-cell lymphoma (DLBCL is the most common type of non-Hodgkin lymphoma (NHL, representing approximately 25% of diagnosed NHL. DLBCL is heterogeneous disease both clinically and genetically. The 3 most common chromosomal translocations in DLBCL involve the oncogenes BCL2, BCL6, and MYC. Double hit (DH DLBCL is an aggressive form in which MYC rearrangement is associated with either BCL2 or BCL6 rearrangement. Patients typically present with a rapidly growing mass, often with B symptoms. Extranodal disease is often present. Though there is a paucity of prospective trials in this subtype, double hit lymphoma (DHL has been linked to very poor outcomes when patients are treated with standard R-CHOP. There is, therefore, a lack of consensus regarding the standard treatment for DHL. Several retrospective analyses have been conducted to help guide treatment of this disease. These suggest that DA EPOCH-R may be the most promising regimen and that achievement of complete resolution predicts better long-term outcomes.

  15. Nonlinear dynamics of a rotating double pendulum

    Energy Technology Data Exchange (ETDEWEB)

    Maiti, Soumyabrata, E-mail: [Department of Mechanical Engineering, Indian Institute of Engineering Science and Technology, Shibpur, 711103 (India); Roy, Jyotirmoy, E-mail: [UM-DAE Centre for Excellence in Basic Sciences, Santa Cruz, Mumbai, 400098 (India); Mallik, Asok K., E-mail: [Department of Applied Mechanics and Aerospace Engineering, Indian Institute of Engineering Science and Technology, Shibpur, 711103 (India); Bhattacharjee, Jayanta K., E-mail: [Harish-Chandra Research Institute, Allahabad, 211019 (India)


    Nonlinear dynamics of a double pendulum rotating at a constant speed about a vertical axis passing through the top hinge is investigated. Transitions of oscillations from chaotic to quasiperiodic and back to chaotic again are observed with increasing speed of rotation. With increasing speed, a pair of new stable equilibrium states, different from the normal vertical one, appear and the quasiperiodic oscillations occur. These oscillations are first centered around the origin, but with increasing rotation speed they cover the origin and the new fixed points. At a still higher speed, more than one pair of fixed points appear and the oscillation again turns chaotic. The onset of chaos is explained in terms of internal resonance. Analytical and numerical results confirm the critical values of the speed parameter at various transitions. - Highlights: • The rotating double pendulum shows transitions from chaos to order and back to chaos. • These transitions occur as the rotation speed is increased. • The dynamics is quasi-periodic in the ordered state. • Within the ordered state the nature of quasi-periodicity changes with rotation speed. • The chaotic state always emerges as a result of an internal resonance.

  16. Inherited thrombophilia: a double-edged sword. (United States)

    Middeldorp, Saskia


    Inherited thrombophilia is a blood coagulation disorder that increases the risk for venous thromboembolism (VTE). During the last decades, the practice of testing has evolved from testing selected populations, leading to high perceived risks, to broad testing for various conditions that included VTE, arterial thrombosis, and pregnancy complications. Because results of such tests usually do not guide treatment decisions, not testing patients with VTE for inherited thrombophilia is on the "Choosing Wisely" list endorsed by multiple specialty societies, including ASH. Inherited thrombophilia can be regarded a double-edged sword, as despite the rationale not to test, it is still being performed frequently. Another way of seeing inherited thrombophilia as a double-edged sword lies in its 2-sided association with reproduction, both in men and in women. Current areas of research are whether women with inherited thrombophilia and pregnancy complications benefit from anticoagulant therapy with regard to improving the chance of a successful pregnancy. Potential effects of inherited thrombophilia, most notably factor V Leiden, on improved embryo implantation in women and sperm counts in men are intriguing, but are currently poorly understood. © 2016 by The American Society of Hematology. All rights reserved.

  17. Recurrent Pneumonia due to Double Aortic Arch

    Directory of Open Access Journals (Sweden)

    I. Sedighi


    Full Text Available Introduction: Pneumonia is one of the most common infections during childhood. In children with recurrent bacterial pneumonia complete evaluation for underlying factors is necessary. The most common underlying diseases include: antibody deficiencies , cystic fibrosis , tracheoesophageal fistula and increased pulmonary blood flow. Vascular ring and its pressure effect is a less common cause of stridor and recurrent pneumonia. Congenital abnormalities in aortic arch and main branches which form vascular ring around esophagus and trachea with variable pressure effect cause respiratory symptoms such as stridor , wheezing and recurrent pneumoniaCase Report: A 2 year old boy was admitted in our hospital with respiratory distress and cough . Chest x-Ray demonstrated right lobar pneumonia. He had history of stridor and wheezing from neonatal period and hospitalization due to pneumonia for four times. The patient received appropriate antibiotics. Despite fever and respiratory distress improvement, wheezing continued. Review of his medical documents showed fixed pressure effect on posterior aspect of esophagus in barium swallow. In CT angiography we confirmed double aortic arch.Conclusion: Double aortic arch is one of the causes of persistant respiratory symptom and recurrent pneumonia in children for which fluoroscopic barium swallow is the first non-invasive diagnostic method.(Sci J Hamadan Univ Med Sci 2012;19(1:70-74

  18. Neutrinoless double beta decay search with SNO+

    Directory of Open Access Journals (Sweden)

    Lozza V.


    Full Text Available The SNO+ experiment is the follow up of SNO. The detector is located 2 km underground in the Vale Canada Ltd.’s Creighton Mine near Sudbury, Ontario, Canada. The active volume of the detector consists of 780 tonnes of Linear Alkyl Benzene (LAB in an acrylic vessel of 12 m diameter, surrounded by about 9500 PMTs. The main goal of the SNO+ experiment is the search for neutrinoless double beta decay of 130Te. With an initial loading of 0.3% of natural tellurium (nearly 800 kg of 130Te, it is expected to reach a sensitivity on the effective Majorana neutrino mass of about 100 meV after several years of data taking. Designed as a general purpose neutrino experiment, other exciting physical goals can be explored, like the measurement of reactor neutrino oscillations and geo-neutrinos in a geologically-interesting location, watch of supernova neutrinos and studies of solar neutrinos. A first commissioning phase with water filled detector will start at the end of 2013, while the double beta decay phase will start in 2015.

  19. Neutrinoless double beta decay search with SNO+ (United States)

    Lozza, V.


    The SNO+ experiment is the follow up of SNO. The detector is located 2 km underground in the Vale Canada Ltd.'s Creighton Mine near Sudbury, Ontario, Canada. The active volume of the detector consists of 780 tonnes of Linear Alkyl Benzene (LAB) in an acrylic vessel of 12 m diameter, surrounded by about 9500 PMTs. The main goal of the SNO+ experiment is the search for neutrinoless double beta decay of 130Te. With an initial loading of 0.3% of natural tellurium (nearly 800 kg of 130Te), it is expected to reach a sensitivity on the effective Majorana neutrino mass of about 100 meV after several years of data taking. Designed as a general purpose neutrino experiment, other exciting physical goals can be explored, like the measurement of reactor neutrino oscillations and geo-neutrinos in a geologically-interesting location, watch of supernova neutrinos and studies of solar neutrinos. A first commissioning phase with water filled detector will start at the end of 2013, while the double beta decay phase will start in 2015.

  20. Double Retort System for Materials Compatibility Testing

    Energy Technology Data Exchange (ETDEWEB)

    V. Munne; EV Carelli


    With Naval Reactors (NR) approval of the Naval Reactors Prime Contractor Team (NRPCT) recommendation to develop a gas cooled reactor directly coupled to a Brayton power conversion system as the Space Nuclear Power Plant (SNPP) for Project Prometheus (References a and b) there was a need to investigate compatibility between the various materials to be used throughout the SNPP. Of particular interest was the transport of interstitial impurities from the nickel-base superalloys, which were leading candidates for most of the piping and turbine components to the refractory metal alloys planned for use in the reactor core. This kind of contamination has the potential to affect the lifetime of the core materials. This letter provides technical information regarding the assembly and operation of a double retort materials compatibility testing system and initial experimental results. The use of a double retort system to test materials compatibility through the transfer of impurities from a source to a sink material is described here. The system has independent temperature control for both materials and is far less complex than closed loops. The system is described in detail and the results of three experiments are presented.

  1. Appendicitis in double cecal appendix: Case report. (United States)

    Alves, José Roberto; Maranhão, Icaro Godeiro de Oliveira; de Oliveira, Patrick Vanttinny Vieira


    Double cecal appendix is a rare anatomical variation. Approximately 100 cases have been reported worldwide. It is usually diagnosed incidentally during emergency appendectomies due to inflammatory processes in the cecal appendix. male, white, 36 years old, obese, presenting with pain in the lower abdomen for 24 h followed by nausea, vomiting and mild fever. He was subjected to additional tests, with the leukogram showing leukocytosis and abdominal ultrasonography depicting cecal appendix with thickened wall, locally associated with small quantities of liquid and intestinal loop obstruction. He underwent laparotomy, revealing acute appendicitis. Another intestinal loop obstruction was identified next to the ileum, leading to recognizing another cecal appendix after local dissection. Double appendectomy and segmental iliectomy were performed although not needed. Results of the anatomopathological examination of the surgical samples showed acute inflammation in the two cecal appendices. So, performing a routine retroperitoneal release and a complete cecum evaluation during such surgical procedures is recommended and suggested due to the possibility of not identifying a second cecal appendix.

  2. Dealing with double trouble: consequences of single and double herbivory in Brassica juncea

    NARCIS (Netherlands)

    Mathur, V.; Tytgat, T.O.G.; Graaf, de R.M.; Kalia, V.; Reddy, A.S.; Vet, L.E.M.; Dam, van N.M.


    In their natural environment, plants are often attacked simultaneously by many insect species. The specificity of induced plant responses that is reported after single herbivore attacks may be compromised under double herbivory and this may influence later arriving herbivores. The present study

  3. Double layer of platinum electrodes: Non-monotonic surface charging phenomena and negative double layer capacitance. (United States)

    Huang, Jun; Zhou, Tao; Zhang, Jianbo; Eikerling, Michael


    In this study, a refined double layer model of platinum electrodes accounting for chemisorbed oxygen species, oriented interfacial water molecules, and ion size effects in solution is presented. It results in a non-monotonic surface charging relation and a peculiar capacitance vs. potential curve with a maximum and possibly negative values in the potential regime of oxide-formation.

  4. Double parton scattering in the ultraviolet. Addressing the double counting problem

    Energy Technology Data Exchange (ETDEWEB)

    Diehl, Markus [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Gaunt, Jonathan R. [Nationaal Inst. voor Kernfysica en Hoge-Energiefysica (NIKHEF), Amsterdam (Netherlands); Vrije Univ. Amsterdam (Netherlands)


    In proton-proton collisions there is a smooth transition between the regime of double parton scattering, initiated by two pairs of partons at a large relative distance, and the regime where a single parton splits into a parton pair in one or both protons. We present a scheme for computing both contributions in a consistent and practicable way.

  5. Eddy turbulence, the double mesopause, and the double layer of atomic oxygen

    Directory of Open Access Journals (Sweden)

    M. N. Vlasov


    Full Text Available In this study, we consider the impact of eddy turbulence on temperature and atomic oxygen distribution when the peak of the temperature occurs in the upper mesosphere. A previous paper (Vlasov and Kelley, 2010 considered the simultaneous impact of eddy turbulence on temperature and atomic oxygen density and showed that eddy turbulence provides an effective mechanism to explain the cold summer and warm winter mesopause observed at high latitudes. Also, the prevalent role of eddy turbulence in this case removes the strong contradiction between seasonal variations of the O density distribution and the impact of upward/downward motion corresponding to adiabatic cooling/heating of oxygen atoms. Classically, there is a single minimum in the temperature profile marking the location of the mesopause. But often, a local maximum in the temperature is observed in the height range of 85–100 km, creating the appearance of a double mesopause (Bills and Gardner, 1993; Yu and She, 1995; Gusev et al., 2006. Our results show that the relative temperature maximum in the upper mesosphere (and thus the double mesopause can result from heating by eddy turbulence. According to our model, there is a close connection between the extra temperature peak in the mesosphere and the oxygen atom density distribution. The main feature of the O density height profile produced by eddy turbulence in our model is a double peak instead of a single peak of O density. A rocket experiment called TOMEX confirms these results (Hecht et al., 2004. Applying our model to the results of the TOMEX rocket campaign gives good agreement with both the temperature and oxygen profiles observed. Climatology of the midlatitude mesopause and green line emission shows that the double mesopause and the double layers of the green line emission, corresponding to the double O density height profile, are mainly observed in spring and fall (Yu and She, 1995; Liu and Shepherd, 2006. Further observations of

  6. A Weekend Workshop on Double Stars for Students (United States)

    Brewer, Mark; Estrada, Chris; Estrada, Reed; Gillette, Sean


    A weekend double star workshop was held by Vanguard Preparatory for selected eighth grade students with the purpose of introducing them to astrometric observational science. The students were selected based on an essay provided by their language arts class. Collaboration with local visiting astronomers was established to provide telescopes equipped with an astrometric eyepiece, observational supervision, and expertise. During the workshop students learned how to determine the scale constant of an astrometric eyepiece, and the procedure for measuring separations and position angles of double stars. The students compared their data to past measurements reported in the Washington Double Star Catalog. Three goals were set for the student's outcome: 1) observe, record, and report observations of double stars, 2) write a scientific paper for publication in the Journal of Double Star Observations, and 3) present a PowerPoint presentation to their peers. This paper chronicles the planning, preparation, funding, and execution required to complete a double star workshop at a public middle school.

  7. Double sigmoidal models describing the growth of coffee berries

    Directory of Open Access Journals (Sweden)

    Tales Jesus Fernandes

    Full Text Available ABSTRACT: This study aimed to verify if the growth pattern of coffee berries, considering fresh mass accumulation over time, is double sigmoid and to select the most suitable nonlinear model to describe such behavior. Data used consisted of fourteen longitudinal observations of average fresh mass of coffee berries obtained in an experiment with the cultivar Obatã IAC 1669-20. The fits provided by the Logistic and Gompertz models were compared in their single and double versions. Parameters were estimated using the least squares method using the Gauss-Newton algorithm implemented in the nls function of the R software. It can be concluded that the growth pattern of the coffee fruit, in fresh mass accumulation, is double sigmoid. The double Gompertz and double Logistic models were adequate to describe such a growth curve, with a superiority of the double Logistic model.

  8. Measuring Visual Double Stars with Robotic Telescopes (United States)

    Boyce, Pat; Boyce, Grady; Genet, Russell M.; Faisal Al-Zaben, Dewei Li, Yongyao Li, Aren Dennis, Zhixin Cao, Junyao Li, Steven Qu, Jeff Li, Michael Fene, Allen Priest, Stephen Priest, Rex Qiu, , and, Bill Riley


    produce four published research papers on seven visual double star systems and have our data added to the Washington Double Star Catalog. A school can adopt these techniques to do visual double star research with a minimal investment.

  9. STT Doubles with Large Delta_M - Objects Nearby (United States)

    Nanson, John; Knapp, Wilfried


    Following our series of reports on STT doubles with large delta_M, we are submitting measurements of WDS objects which were by chance found nearby in the images taken of the STT doubles. In these cases we did not suspect any issues with the current WDS catalog data, but wanted to make use of existing image material as any double star visited is worth a current measurement.

  10. Wave Propagation Characteristics in Functionally Graded Double-Beams

    Directory of Open Access Journals (Sweden)

    Fatih Karacam


    Full Text Available The wave propagation characteristics of functionally graded (FG double-beams are investigated by use of Euler-Bernoulli beam theory. Two beams are connected by a Winkler foundation. The wave propagation characteristics like frequency, phase and group velocities are obtained for different wave numbers and material properties. Four frequencies are obtained for functionally graded double-beam system. It is obtained that flexural and axial waves are coupled for FG double-beams.

  11. Modifying the double smoothing bandwidth selector in nonparametric regression


    Beran, Jan; Feng, Yuanhua; Heiler, Siegfried


    In this paper a modified double smoothing bandwidth selector, ^h MDS , based on a new criterion, which combines the plug-in and the double smoothing ideas, is proposed. A self-complete iterative double smoothing rule ( ^ h IDS ) is introduced as a pilot method. The asymptotic properties of both ^ h IDS and ^ h MDS are investigated. It is shown that ^ h MDS performs asymptotically very well. Moreover, it is asymptotically negatively correlated with h ASE , the minimizer of the averaged squared...

  12. Torus-doubling process via strange nonchaotic attractors (United States)

    Mitsui, Takahito; Uenohara, Seiji; Morie, Takashi; Horio, Yoshihiko; Aihara, Kazuyuki


    Torus-doubling bifurcations typically occur only a finite number of times. It has been assumed that torus-doubling bifurcations in quasiperiodically forced systems are interrupted by the appearance of strange nonchaotic attractors (SNAs). In the present Letter, we study a quasiperiodically forced noninvertible map and report the occurrence of a torus-doubling process via SNAs. The mechanism of this process is numerically clarified. Furthermore, this process is experimentally demonstrated in a switched-capacitor integrated circuit.

  13. The double bind : Women, honour and sexuality in contemporary Ireland


    Inglis, Tom; MacKeogh, Carol


    Irish women are caught in contradictory sexual discourses which create a cultural double bind. The legacy of Catholic Church teaching, in which the sexual honour of women revolves around their innocence and subservience, still lingers. This is gradually being replaced by media messages and images which portray women as sexually equal and independent. However, the media also portray sexually independent women as a threat to sexual moral order. The double bind reproduces double standards. The c...

  14. The double bind of audit culture in Romania

    National Research Council Canada - National Science Library

    Vintilă Mihăilescu


    .... The case of academic competition between anthropology and ethnology is scrutinized in order to illustrate the double standards, nationally and globally oriented, of the quantitative metrics promoted...

  15. Studies of double parton interactions with the ATLAS detector

    CERN Document Server

    AUTHOR|(INSPIRE)INSPIRE-00227648; The ATLAS collaboration


    The contributions of double and multiple parton scattering are sizable in many physics processes at the LHC, especially in the region of low particle transverse momenta. Studies of double-parton scattering using various final states, i.e. W+dijet, W+J/Psi, Z+J/Psi, double-J/psi and four-jet events, are presented along with measurements of the effective cross section, exploiting the different kinematic configurations of events with the double parton and single parton scattering.

  16. Modelling of observed double-junction effect

    CERN Document Server

    Menichelli, D; Li, Z; Eremin, V


    New TCT measurements reveal the existence of a strong electric field, before full depletion, near both p sup + and n sup + side of high- and medium-resistivity silicon detectors, irradiated over space-charge sign inversion. More, by injecting carriers near the low-field side, double-peaked TCT current pulses are observed. This fact can be justified by assuming the presence of two deep levels in the gap, an acceptor like above mid-gap, and a donor like in the lower half of the gap, which can support the existence of two depleted regions. Particularly, the theoretical analysis of the TCT current profiles has been developed, and the second peak existence has been explained as the effect of carriers re-injection from ENB inside depleted regions.

  17. Predicting tilt of a double pendulum (United States)

    Strom, George J.


    An iterative computer method is described that has been used to calculate the proper settings of the lengths of six turnbuckles used in the hoisting of the 24,000-lb Hubble Space Telescope and components during assembly. The various sections are required to hang very close to level (within a few arc-seconds) when hoisted. The hoisting gear is a delta (triangular) frame suspended by three chains from a single hook on the hoist. Three long cables attached to the bottom of the frame are attached to the Space Telescope. The chains and frame and the cables and telescope together constitute a double pendulum. After correcting some errors in the CG calculations and fixing a large discrepancy in the supposed coordinates of the attach points, a nearly perfect result (6 arcmin tilt in one plane, 3 arcmin in the other) was obtained. The program gives a satisfactory answer in 30 seconds; at most, one adjustment of the turnbuckles is required.

  18. Regression Estimator Using Double Ranked Set Sampling

    Directory of Open Access Journals (Sweden)

    Hani M. Samawi


    Full Text Available The performance of a regression estimator based on the double ranked set sample (DRSS scheme, introduced by Al-Saleh and Al-Kadiri (2000, is investigated when the mean of the auxiliary variable X is unknown. Our primary analysis and simulation indicates that using the DRSS regression estimator for estimating the population mean substantially increases relative efficiency compared to using regression estimator based on simple random sampling (SRS or ranked set sampling (RSS (Yu and Lam, 1997 regression estimator.  Moreover, the regression estimator using DRSS is also more efficient than the naïve estimators of the population mean using SRS, RSS (when the correlation coefficient is at least 0.4 and DRSS for high correlation coefficient (at least 0.91. The theory is illustrated using a real data set of trees.

  19. Fiber tractography assessment in double cortex syndrome. (United States)

    Iannetti, Paola; Nicita, Francesco; Spalice, Alberto; Parisi, Pasquale; Papetti, Laura; Verrotti, Alberto


    Subcortical band heterotopia (SBH) or double cortex syndrome is a malformation of cortical development that may be related to intractable epilepsy and severe mental retardation or to mild epilepsy and slight mental delay or normal cognitive functions. Several studies have been performed using neuroradiological or neurophysiological techniques, like SPECT, PET, MRS, fMRI, and MEG, in attempt to better characterize this neuronal migration disorder. Recently, also diffusion tensor imaging (DTI) and fiber tracking (FT) have been used to investigate on white matter anomalies in SBH, adding more information about such gray matter anomaly. We report on three cases of SBH, evaluated with MRI, DTI, and FT. The data gathered from DTI and TF allow us to hypothesize a new functional role for heterotopic gray matter.

  20. Standard Model as a Double Field Theory. (United States)

    Choi, Kang-Sin; Park, Jeong-Hyuck


    We show that, without any extra physical degree introduced, the standard model can be readily reformulated as a double field theory. Consequently, the standard model can couple to an arbitrary stringy gravitational background in an O(4,4) T-duality covariant manner and manifest two independent local Lorentz symmetries, Spin(1,3)×Spin(3,1). While the diagonal gauge fixing of the twofold spin groups leads to the conventional formulation on the flat Minkowskian background, the enhanced symmetry makes the standard model more rigid, and also stringy, than it appeared. The CP violating θ term may no longer be allowed by the symmetry, and hence the strong CP problem can be solved. There are now stronger constraints imposed on the possible higher order corrections. We speculate that the quarks and the leptons may belong to the two different spin classes.