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Sample records for metallocene dichlorides identified

  1. Electrochemistry of vanadocene dichloride in tetrahydrofuran and general scheme of the electroreduction of metallocene dichlorides of subgroups IVB-VIB

    Energy Technology Data Exchange (ETDEWEB)

    Kuzharenko, S.V.; Strelets, V.V.

    1987-08-10

    In tetrahydrofuran medium on a dropping mercury electrode, vanadocene dichloride undergoes reversible one-electron reduction to a metastable vanadocene dichloride anion on the first wave; this anion is reversibly dehalogenated in the layer near the electrode, forming vanadocene monochloride. On the second wave there is an irreversible one-electron reduction of vanadocene monochloride to vanadocene. The reversible one-electron reduction of vanadocene on the third wave leads to the formation of metastable anion Cp/sub 2/V/sup -/ as the primary product. A general scheme is proposed for the electroreduction of metallocene dichlorides of subgroups IVB-VIB.

  2. Trends in Covalency for d- and f-Element Metallocene Dichlorides Identified Using Chlorine K-Edge X-Ray Absorption Spectroscopy and Time Dependent-Density Functional Theory

    Energy Technology Data Exchange (ETDEWEB)

    Kozimor, Stosh A.; Yang, Ping; Batista, Enrique R.; Boland, Kevin S.; Burns, Carol J.; Clark, David L.; Conradson, Steven D.; Martin, Richard L.; Wikerson, Marianne P.; Wolfsberg, Laura E.

    2009-09-02

    We describe the use of Cl K-edge X-ray Absorption Spectroscopy (XAS) and both ground state and time-dependent hybrid density functional theory (DFT) to probe electronic structure and determine the degree of orbital mixing in M-Cl bonds for (C5Me5)2MCl2 (M = Ti, 1; Zr, 2; Hf, 3; Th, 4; and U, 5), where we can directly compare a class of structurally similar compounds for d- and f-elements. We report direct experimental evidence for covalency in M-Cl bonding, including actinides, and offer insight into the relative roles of the valence f- and dorbitals in these systems. The Cl K-edge XAS data for the group IV transition metals, 1 – 3, show slight decreases in covalency in M-Cl bonding with increasing principal quantum number, in the order Ti > Zr > Hf. The percent Cl 3p character per M-Cl bond was experimentally determined to be 25, 23, and 22% per M-Cl bond for 1-3, respectively. For actinides, we find a shoulder on the white line for (C5Me5)2ThCl2, 4, and distinct, but weak pre-edge features for 2 (C5Me5)2UCl2, 5. The percent Cl 3p character in Th-Cl bonds in 4 was determined to be 14 %, with high uncertainty, while the U-Cl bonds in 5 contains 9 % Cl 3p character. The magnitudes of both values are approximately half what was observed for the transition metal complexes in this class of bent metallocene dichlorides. Using the hybrid DFT calculations as a guide to interpret the experimental Cl K-edge XAS, these experiments suggest that when evaluating An- Cl bonding, both 5f- and 6d-orbitals should be considered. For (C5Me5)2ThCl2, the calculations and XAS indicate that the 5f- and 6d-orbitals are nearly degenerate and heavily mixed. In contrast, the 5f- and 6d-orbitals in (C5Me5)2UCl2 are no longer degenerate, and fall in two distinct energy groupings. The 5f-orbitals are lowest in energy and split into a 5-over-2 pattern with the high lying U 6d-orbitals split in a 4-over-1 pattern, the latter of which is similar to the dorbital splitting in group IV transition

  3. A molecular docking study of the interactions between human transferrin and seven metallocene dichlorides.

    Science.gov (United States)

    Güette-Fernández, Jorge R; Meléndez, Enrique; Maldonado-Rojas, Wilson; Ortega-Zúñiga, Carlos; Olivero-Verbel, Jesus; Parés-Matos, Elsie I

    2017-08-01

    Human Transferrin (hTf) is a metal-binding protein found in blood plasma and is well known for its role in iron delivery. With only a 30% of its capacity for Fe +3 binding, this protein has the potential ability to transport other metal ions or organometallic compounds from the blood stream to all cell tissues. In this perspective, recent studies have described seven metallocene dichlorides (Cp 2 M(IV)Cl 2 , M(IV)=V, Mo, W, Nb, Ti, Zr, Hf) suitable as anticancer drugs and less secondary effects than cisplatin. However, these studies have not provided enough data to clearly explain how hTf binds and transports these organometallic compounds into the cells. Thus, a computational docking study with native apo-hTf using Sybyl-X 2.0 program was conducted to explore the binding modes of these seven Cp 2 M(IV)Cl 2 after their optimization and minimization using Gaussian 09. Our model showed that the first three Cp 2 M(IV)Cl 2 (M(IV)=V, Mo, W) can interact with apo-hTf on a common binding site with the amino acid residues Leu-46, Ile-49, Arg-50, Leu-66, Asp-69, Ala-70, Leu-72, Ala-73, Pro-74 and Asn-75, while the next four Cp 2 M(IV)Cl 2 (M(IV)=Nb, Ti, Zr, Hf) showed different binding sites, unknown until now. A decreasing order in the total score (equal to -log Kd) was observed from these docking studies: W (5.4356), Mo (5.2692), Nb (5.1672), V (4.5973), Ti (3.6529), Zr (2.0054) and Hf (1.8811). High and significant correlation between the affinity of these seven ligands (metallocenes) for apo-hTf and their bond angles CpMCp (r=0.94, p<0.01) and Cl-M-Cl (r=0.95, p<0.01) were observed, thus indicating the important role that these bond angles can play in ligand-protein interactions. Fluorescence spectra of apo-hTf, measured at pH 7.4, had a decrease in the fluorescence emission spectrum with increasing concentration of Cp 2 M(IV)Cl 2 . Experimental data has a good correlation between K A (r=0.84, p=0.027) and K d (r=0.94, p=0.0014) values and the calculated total scores

  4. Causes of the different catalytic activity of metallocene dichlorides of subgroups IVB-VIB in the amalgam reduction of carbon monoxide

    Energy Technology Data Exchange (ETDEWEB)

    Strelets, V.V.; Kuzharenko, S.V.; Tsarev, V.N.

    1987-08-10

    Vanadocene, generated by the amalgam reduction of Cp/sub 2/VCl/sub 2/ (Cp = eta/sup 5/-C/sub 5/H/sub 5/) in a medium of aprotic solvents (DMFA, THF, dimethylacetamide, DMSO, etc.), containing phenol as a proton donor, effectively catalyzes the reduction of CO by sodium amalgam at approx. 20/sup 0/C and 1 atm with the formation of C/sub 1/-C/sub 4/ hydrocarbons. In this work they studied the catalytic activity of other complexes of metals of subgroups IVB-VIB (M = Ti, Nb, Mo, W) in the amalgam reduction of CO in THF and DMFA medium. Differences in the catalytic activity of metallocene dichlorides of subgroups IVB-VIB in the amalgam reduction of carbon monoxide are due to thermodynamic factors determining the impossibility of amalgam reduction of the catalyst-substrate complex (subgroup IV) and differences in the stability of the corresponding metallocene (subgroups VB and VIB). Amalgam reduction of carbon monoxide, bound in a complex with metallocene, occurs under conditions of transfer of the first electron against the potential gradient.

  5. Theoretical and experimental prediction of the redox potentials of metallocene compounds

    Science.gov (United States)

    Li, Ya-Ping; Liu, Hai-Bo; Liu, Tao; Yu, Zhang-Yu

    2017-11-01

    The standard redox electrode potential ( E°) values of metallocene compounds are obtained theoretically with density functional theory (DFT) method at B3LYP/6-311++G( d, p) level and experimentally with cyclic voltammetry (CV). The theoretical E° values of metallocene compounds are in good agreement with experimental ones. We investigate the substituent effects on the redox properties of metallocene compounds. Among the four metallocene compounds, the E° values is largest for titanocene dichloride and smallest for ferrocene.

  6. Paraquat Dichloride

    Science.gov (United States)

    Paraquat dichloride, commonly referred to as “paraquat,” is one of the most widely used herbicides registered in the United States. Paraquat is also often referred to as Gramoxone (a popular end-use product).

  7. Covalency Trends in Group IV Metallocene Dichlorides. Chlorine K-Edge X-Ray Absorption Spectroscopy And Time Dependent-Density Functional Theory

    Energy Technology Data Exchange (ETDEWEB)

    Kozimor, S.A.; Yang, P.; Batista, E.R.; Boland, K.S.; Burns, C.J.; Christensen, C.N.; Clark, D.L.; Conradson, S.D.; Hay, P.J.; Lezama, J.S.; Martin, R.L.; Schwarz, D.E.; Wilkerson, M.P.; Wolfsberg, L.E.

    2009-05-20

    For 3-5d transition-metal ions, the (C{sub 5}R{sub 5}){sub 2}MCl{sub 2} (R = H, Me for M = Ti, Zr, Hf) bent metallocenes represent a series of compounds that have been central in the development of organometallic chemistry and homogeneous catalysis. Here, we evaluate how changes in the principal quantum number for the group IV (C{sub 5}H{sub 5}){sub 2}MCl{sub 2} (M = Ti, Zr, Hf; 1-3, respectively) complexes affects the covalency of M-Cl bonds through application of Cl K-edge X-ray Absorption Spectroscopy (XAS). Spectra were recorded on solid samples dispersed as a thin film and encapsulated in polystyrene matrices to reliably minimize problems associated with X-ray self-absorption. The data show that XAS pre-edge intensities can be quantitatively reproduced when analytes are encapsulated in polystyrene. Cl K-edge XAS data show that covalency in M-Cl bonding changes in the order Ti > Zr > Hf and demonstrates that covalency slightly decreases with increasing principal quantum number in 1-3. The percent Cl 3p character was experimentally determined to be 26, 23, and 18% per M-Cl bond in the thin-film samples for 1-3 respectively and was indistinguishable from the polystyrene samples, which analyzed as 25, 25, and 19% for 1-3, respectively. To aid in interpretation of Cl K-edge XAS, 1-3 were also analyzed by ground-state and time-dependent density functional theory (TD-DFT) calculations. The calculated spectra and percent chlorine character are in close agreement with the experimental observations, and show 20, 18, and 17% Cl 3p character per M-Cl bond for 1-3, respectively. Polystyrene matrix encapsulation affords a convenient method to safely contain radioactive samples to extend our studies to include actinide elements, where both 5f and 6d orbitals are expected to play a role in M-Cl bonding and where transition assignments must rely on accurate theoretical calculations.

  8. Carbon K-edge X-ray absorption spectroscopy and time-dependent density functional theory examination of metal-carbon bonding in metallocene dichlorides.

    Science.gov (United States)

    Minasian, Stefan G; Keith, Jason M; Batista, Enrique R; Boland, Kevin S; Kozimor, Stosh A; Martin, Richard L; Shuh, David K; Tyliszczak, Tolek; Vernon, Louis J

    2013-10-02

    Metal-carbon covalence in (C5H5)2MCl2 (M = Ti, Zr, Hf) has been evaluated using carbon K-edge X-ray absorption spectroscopy (XAS) as well as ground-state and time-dependent hybrid density functional theory (DFT and TDDFT). Differences in orbital mixing were determined experimentally using transmission XAS of thin crystalline material with a scanning transmission X-ray microscope (STXM). Moving down the periodic table (Ti to Hf) has a marked effect on the experimental transition intensities associated with the low-lying antibonding 1a1* and 1b2* orbitals. The peak intensities, which are directly related to the M-(C5H5) orbital mixing coefficients, increase from 0.08(1) and 0.26(3) for (C5H5)2TiCl2 to 0.31(3) and 0.75(8) for (C5H5)2ZrCl2, and finally to 0.54(5) and 0.83(8) for (C5H5)2HfCl2. The experimental trend toward increased peak intensity for transitions associated with 1a1* and 1b2* orbitals agrees with the calculated TDDFT oscillator strengths [0.10 and 0.21, (C5H5)2TiCl2; 0.21 and 0.73, (C5H5)2ZrCl2; 0.35 and 0.69, (C5H5)2HfCl2] and with the amount of C 2p character obtained from the Mulliken populations for the antibonding 1a1* and 1b2* orbitals [8.2 and 23.4%, (C5H5)2TiCl2; 15.3 and 39.7%, (C5H5)2ZrCl2; 20.1 and 50.9%, (C5H5)2HfCl2]. The excellent agreement between experiment, theory, and recent Cl K-edge XAS and DFT measurements shows that C 2p orbital mixing is enhanced for the diffuse Hf (5d) and Zr (4d) atomic orbitals in relation to the more localized Ti (3d) orbitals. These results provide insight into how changes in M-Cl orbital mixing within the metallocene wedge are correlated with periodic trends in covalent bonding between the metal and the cyclopentadienide ancillary ligands.

  9. Reversible photoisomerization of a d0-metallocene

    International Nuclear Information System (INIS)

    Lukova, G.V.; Smirnov, V.A.; Zenchuk, E.V.

    2006-01-01

    A reversible photochemical isomerization of rac-isomer↔racelyc mixture, when irradiation is alternated in different regions of the UV spectrum, has been detected for the first time for class d 0 -metallocenes, bis(tetrahydroindenyl)zirconium dichloride with a trans-cyclohexyl bridge specifically. It is shown that in all probability photoinduced isomerization occurs by the dissociative mechanism from the short-lived singlet electron-excited state [ru

  10. Ansa-metallocene polymerization catalysts derived from [2+2]cycloaddition reactions of bis(1-methylethenyl-cyclopentadienyl)zirconium systems

    Science.gov (United States)

    Paradies, Jan; Kehr, Gerald; Fröhlich, Roland; Erker, Gerhard

    2006-01-01

    Bis(1-methylethenyl-cyclopentadienyl)zirconium dichloride (7a) was prepared by a fulvene route. Photolysis at 0°C with Pyrex-filtered UV light resulted in a rapid and complete intramolecular [2+2]cycloaddition reaction to yield the corresponding cyclobutylene-bridged ansa-zirconocene dichloride isomer (8a). This is one of the rare examples of an organic functional group chemistry that leads to carbon–carbon coupling at the framework of an intact sensitive group 4 bent metallocene complex. More sterically hindered open metallocenes that bear bulky isopropyl or tert-butyl substituents at their Cp rings in addition to the active 1-methylethenyl functional group undergo the photochemical ansa-metallocene ring closure reaction equally facile. The metallocene systems used and obtained in this study have served as transition metal components for the generation of active metallocene propene polymerization catalysts. PMID:17032775

  11. Metallocenes and metallocene derivatives having a radioactive central atom

    Energy Technology Data Exchange (ETDEWEB)

    Wenzel, M.; Langheim, D.

    1977-06-07

    Radioactive metallocenes and metallocene derivatives are prepared by heating a non-radioactive metallocene or metallocene derivative with a radioactive metal salt, e.g., /sup 103/RuCl/sub 3/, at 140 to 250/sup 0/C.

  12. Binuclear metallocene

    International Nuclear Information System (INIS)

    Lemenovskij, D.A.; Fedin, V.P.

    1986-01-01

    Analysis of data on synthesis methods and chemical transformations in bis-metal-locene complexes of transition elements of 4-6 groups of the Periodic system is given. Main attention is paid to the detection of a general mechanism of binuclear metallocene structure and transformations as well as to analysis of disagreements arising repeatedly in the course of investigation of these compounds

  13. Metallocene complexes as homogeneous catalysts in olefin polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Alt, H.G. [Universitaet Bayreuth (Germany)

    1995-01-01

    Ansa metallocene dichloride complexes of titanium, zirconium, and hafnium can be activated by methyl aluminoxane (MAO) to give excellent catalysts for the homogeneous polymerization of ethylene and propylene. The symmetry of the corresponding metallocene dichloride complexes is essential for the stereospecific polymerization of propylene (isotactic, syndiotactic or atactic). The application of fluorenyl groups instead of cyclopentadienyl groups greatly increases the activity of the catalysts. The first ansa bis(fluorenyl) complexes of zirconium and hafnium, (C{sub 13}H{sub 8}-C{sub 2}H{sub 4}-C{sub 13}H{sub 8})MCl{sub 2} (M = Zr, Hf), have been prepared. It was found that after the activation by MAO the zirconium derivative demonstrates a very high activity. Several models are presented in order to discuss the mechanism of the polymerization.

  14. Metallocene Based Polyolefin Nanocomposites

    OpenAIRE

    Walter Kaminsky

    2014-01-01

    One of the most efficient and versatile ways to synthesize polyolefin nanocomposites is the in-situ polymerization of olefins in the presence of nano particles by metallocene catalysts. Metallocene/methylaluminoxane (MAO) catalysts are soluble in hydrocarbons and therefore they can be absorbed perfectly in solution onto the surface of particles or fibers and after addition of ethene or propene they can then catalyze a polyolefin film on the surface. Metallocene/MAO and other single site catal...

  15. Electrochemistry of metallocene dichlorides of subgroup IVB in tetrahydrofuran

    Energy Technology Data Exchange (ETDEWEB)

    Kukharenko, S.V.; Soloveichik, G.L.; Strelets, V.V.

    1986-11-10

    The complex metallocenyl chlorides Cp/sub 2/MCl/sub 2/ (M = Ti, Zr, Hf) are reversibly reduced in a THF medium on a dropping mercury electrode to the corresponding metastable radical anions Cp/sub 2/MCl/sub 2//sup -./, which are reversibly converted into the complexes Cp/sub 2/MCl, the rate of the dehalogenation reaction decreases as the temperature is lowered and increases along the series of metals Zr..-->.. Hf ..-->.. Ti. The second reduction wave of the complexes Cp/sub 2/MCl/sub 2/ corresponds to the irreversible one-electron reduction of the complexes Cp/sub 2/MCl/sub 2/, which form in the layer next to the electrode as a result of the dehalogenation of Cp/sub 2/MCl/sub 2//sup -./. The third wave corresponds to the one-electron reduction of the radical anions Cp/sub 2/MCl/sub 2//sup -./ (M = Zr, Hf) or titanocene (M = Ti). The electroreduction of the complexes Cp/sub 2/MCl/sub 2/ to the M(III) and M(II) derivatives becomes increasingly hindered along the series Ti ..-->.. Zr..-->.. Hf. The values of E/sub 1/2/ of the complexes studied are linearly correlated with the fourth and third ionization potentials of the corresponding metals in the gaseous phase.

  16. Crystal structures and stereospecific propylene polymerizations with chiral hafnium metallocene catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Ewen, J.A.; Haspeslagh, L.; Atwood, J.L.; Zhang, H.

    1987-10-14

    Ligand effects on stereoregulation with homogeneous catalysts have been stimulated considerable interest in Ziegler-Natta propylene polymerizations with metallocene catalysts. The major limitations to development in this area have been that the titanium catalysts are unstable at conventional polymerization temperatures, and that the zirconium analogues only produce low molecular weight oligomers in significant quantities. In this contribution, the authors describe the structures and the polymerization behavior of both rac-ethylenebis(indenyl)hafnium(IV) dichloride (rac-Et(Ind)/sub 2/HfCl/sub 2/) and rac-ethylenebis(4,5,6,7-tetrahydro-1-indenyl)hafnium(IV) dichloride (rac-Et-(IndH/sub 4/)/sub 2/HfCl/sub 2/). The results are compared to those with Ti and Zr analogues. The new Hf catalysts are the first metallocenes to provide high yields of high molecular weight isotactic polypropylene.

  17. Metallocene carbene chemistry

    International Nuclear Information System (INIS)

    Ehrker, G.; Ker, G.; Frelikh, R.

    2004-01-01

    A review of chemical properties of group IV element chamfered metallocenes Cp 2 M (M=Ti, Zr, Hf) is presented. It is shown that specific features of their stereoelectronic structure and clearly pronounced oxophily of M metals permit using the complexes as components of reaction systems involving carbenes. The use of ruthenium carbene complexes for realizing the catalytic metathesis of lateral olefin substituents in the chamfered metallocenes is described by way of example [ru

  18. Metallocene Based Polyolefin Nanocomposites

    Directory of Open Access Journals (Sweden)

    Walter Kaminsky

    2014-03-01

    Full Text Available One of the most efficient and versatile ways to synthesize polyolefin nanocomposites is the in-situ polymerization of olefins in the presence of nano particles by metallocene catalysts. Metallocene/methylaluminoxane (MAO catalysts are soluble in hydrocarbons and therefore they can be absorbed perfectly in solution onto the surface of particles or fibers and after addition of ethene or propene they can then catalyze a polyolefin film on the surface. Metallocene/MAO and other single site catalysts allow the synthesis of polymers with a precisely defined microstructure, tacticity, and stereoregularity as well as new copolymers with superior properties such as film clarity, high tensile strength and lower content of extractables. The polymer properties can be enlarged by the incorporation of nanofillers. The resulting polyethylene or polypropylene nanocomposites give a tremendous boost to the physical and chemical properties such as dramatically improved stiffness, high gas barrier properties, significant flame retardancy, and high crystallization rates.

  19. Method of preparing metallocene compounds

    Energy Technology Data Exchange (ETDEWEB)

    Rosenblum, M.; Matchett, S.A.

    1992-06-23

    This invention describes a novel method of preparing metallocene compounds. The invention is based on synthesis of novel bis cyclopentadienides that, under appropriate conditions, will either encapsulate a transition metal to produce a metallocene such as ferrocene, or ferrocene derivative, or will yield a polymeric metallocene. Compounds produced by this process are useful as catalysts in propulsion systems, or as anti-knock compounds in gasolines. 2 figs.

  20. Method of preparing metallocene compounds

    Science.gov (United States)

    Rosenblum, Myron; Matchett, Stephen A.

    1992-01-01

    This invention describes a novel method of preparing metallocene compounds. The invention is based on synthesis of novel bis cyclopentadienides that, under appropriate conditions, will either encapsulate a transition metal to produce a metallocene such as ferrocene, or ferrocene derivative, or will yield a polymeric metallocene. Compounds produced by this process are useful as catalysts in propulsion systems, or as anti-knock compounds in gasolines.

  1. Mass spectrometric characterization of methylaluminoxane-activated metallocene complexes.

    Science.gov (United States)

    Trefz, Tyler K; Henderson, Matthew A; Linnolahti, Mikko; Collins, Scott; McIndoe, J Scott

    2015-02-09

    Electrospray-ionization mass spectrometric studies of poly(methylaluminoxane) (MAO) in the presence of [Cp2 ZrMe2 ], [Cp2 ZrMe(Cl)], and [Cp2 ZrCl2 ] in fluorobenzene (PhF) solution are reported. The results demonstrate that alkylation and ionization are separate events that occur at competitive rates in a polar solvent. Furthermore, there are significant differences in ion-pair speciation that result from the use of metallocene dichloride complexes in comparison to alkylated precursors at otherwise identical Al/Zr ratios. Finally, the counter anions that form are dependent on the choice of precursor and Al/Zr ratio; halogenated aluminoxane anions [(MeAlO)x (Me3 Al)y-z (Me2 AlCl)z Me](-) (z=1, 2, 3…︁) are observed using metal chloride complexes and under some conditions may predominate over their non-halogenated precursors [(MeAlO)x (Me3 Al)y Me](-) . Specifically, this halogenation process appears selective for the anions that form in comparison to the neutral components of MAO. Only at very high Al/Zr ratios is the same "native" anion distribution observed when using [Cp2 ZrCl2 ] when compared with [Cp2 ZrMe2 ]. Together, the results suggest that the need for a large excess of MAO when using metallocene dichloride complexes is a reflection of competitive alkylation vs. ionization, the persistence of unreactive, homodinuclear ion pairs in the case of [Cp2 ZrCl2 ], as well as a change in ion pairing resulting from modification of the anions formed at lower Al/Zr ratios. Models for neutral precursors and anions are examined computationally. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. 21 CFR 173.230 - Ethylene dichloride.

    Science.gov (United States)

    2010-04-01

    ... HUMAN CONSUMPTION (CONTINUED) SECONDARY DIRECT FOOD ADDITIVES PERMITTED IN FOOD FOR HUMAN CONSUMPTION Solvents, Lubricants, Release Agents and Related Substances § 173.230 Ethylene dichloride. A tolerance of...

  3. Metallocene Antimalarials: The Continuing Quest

    OpenAIRE

    Blackie, Margaret A. L.; Chibale, Kelly

    2007-01-01

    Over the last decade, a significant body of research has been developed around the inclusion of a metallocene moiety into known antimalarial compounds. Ferroquine is the most successful of these compounds. Herein, we describe our contribution to metallocene antimalarials. Our approach has sought to introduce diversity sites in the side chain of ferroquine in order to develop a series of ferroquine derivatives. The replacement of the ferrocenyl moiety with ruthenocene has given rise to rutheno...

  4. Hafnium metallocene compounds used as cathode interfacial layers for enhanced electron transfer in organic solar cells

    Science.gov (United States)

    2012-01-01

    We have used hafnium metallocene compounds as cathode interfacial layers for organic solar cells [OSCs]. A metallocene compound consists of a transition metal and two cyclopentadienyl ligands coordinated in a sandwich structure. For the fabrication of the OSCs, poly[3,4-ethylenedioxythiophene]:poly(styrene sulfonate), poly(3-hexylthiophene-2,5-diyl) + [6,6]-phenyl C61 butyric acid methyl ester, bis-(ethylcyclopentadienyl)hafnium(IV) dichloride, and aluminum were deposited as a hole transport layer, an active layer, a cathode interfacial layer, and a cathode, respectively. The hafnium metallocene compound cathode interfacial layer improved the performance of OSCs compared to that of OSCs without the interfacial layer. The current density-voltage characteristics of OSCs with an interfacial layer thickness of 0.7 nm and of those without an interfacial layer showed power conversion efficiency [PCE] values of 2.96% and 2.34%, respectively, under an illumination condition of 100 mW/cm2 (AM 1.5). It is thought that a cathode interfacial layer of an appropriate thickness enhances the electron transfer between the active layer and the cathode, and thus increases the PCE of the OSCs. PMID:22230259

  5. Synthetic transformations of a pendant nitrile moiety in group 4 metallocene complexes.

    Science.gov (United States)

    Pinkas, Jiří; Císařová, Ivana; Kubišta, Jiří; Horáček, Michal; Lamač, Martin

    2013-05-21

    Functional group transformations at the group 4 metallocene framework have been demonstrated, which have provided relatively straightforward access to otherwise synthetically challenging derivatives. The pendant nitrile group in Ti and Zr metallocene complexes of the type [(η(5)-C5Me5)(η(5)-C5H4CMe2CH2CN)MCl2] was converted into an intramolecularly bound ketimido moiety by alkylation, which took place not only at the nitrile, but also at the metal centre. The choice of an alkylating reagent (alkyl/aryl lithium, Grignard reagent) was crucial: e.g., 2 equiv. of MeMgBr effected the alkylation only at the metal, yielding selectively complexes [(η(5)-C5Me5)(η(5)-C5H4CMe2CH2CN)MMe2], while the use of PhMgBr, PhLi, or MeLi instead gave selectively the ketimido complexes. Organyl lithium reagents were, however, not compatible with the titanocene derivatives. The metal-bound ketimides were subsequently cleaved off by the reaction with HCl, which afforded metallocene dichlorides with a pendant imino group. These compounds were easily protonated again at the nitrogen atom to produce a cationic iminium moiety. Aqueous hydrolysis of the imine or its respective hydrochloride proved to be viable in the case of Zr and it finally afforded a pendant ketone group attached to the zirconocene framework.

  6. Hafnium metallocene compounds used as cathode interfacial layers for enhanced electron transfer in organic solar cells

    Science.gov (United States)

    Park, Keunhee; Oh, Seungsik; Jung, Donggeun; Chae, Heeyeop; Kim, Hyoungsub; Boo, Jin-Hyo

    2012-01-01

    We have used hafnium metallocene compounds as cathode interfacial layers for organic solar cells [OSCs]. A metallocene compound consists of a transition metal and two cyclopentadienyl ligands coordinated in a sandwich structure. For the fabrication of the OSCs, poly[3,4-ethylenedioxythiophene]:poly(styrene sulfonate), poly(3-hexylthiophene-2,5-diyl) + [6, 6]-phenyl C61 butyric acid methyl ester, bis-(ethylcyclopentadienyl)hafnium(IV) dichloride, and aluminum were deposited as a hole transport layer, an active layer, a cathode interfacial layer, and a cathode, respectively. The hafnium metallocene compound cathode interfacial layer improved the performance of OSCs compared to that of OSCs without the interfacial layer. The current density-voltage characteristics of OSCs with an interfacial layer thickness of 0.7 nm and of those without an interfacial layer showed power conversion efficiency [PCE] values of 2.96% and 2.34%, respectively, under an illumination condition of 100 mW/cm2 (AM 1.5). It is thought that a cathode interfacial layer of an appropriate thickness enhances the electron transfer between the active layer and the cathode, and thus increases the PCE of the OSCs.

  7. Stability of films impregnated with group IVB metallocene polydyes based on monoazo dyes to high energy radiation

    Energy Technology Data Exchange (ETDEWEB)

    Carraher, C.; Kloss, J.; Medina, F. [Flordia Atlantic Univ., Boca Raton, FL (United States)

    1993-12-31

    A number of polydyes were synthesized based on the condensation of Group IVB metallocene dichlorides and monoazo dyes. These polydyes, and the monomeric reactants, were added to produce films. Stability to various high energy radiations derived from lasers and other high energy radiation sources was tested. By comparison, the films containing the polydyes exhibit markedly shorter {open_quotes}burnthrough{close_quotes} times when employing a laser operating in the UV-Visible region. Addition of polydyes to materials then allow energy to be concentrated thus requiring lesser energy for fabrication of items such as computer chips and other electrical devices and miniaturization of items.

  8. Stability of films impregnated with group IVB metallocene polydyes based on monoazo dyes to high energy radiation

    International Nuclear Information System (INIS)

    Carraher, C.; Kloss, J.; Medina, F.

    1993-01-01

    A number of polydyes were synthesized based on the condensation of Group IVB metallocene dichlorides and monoazo dyes. These polydyes, and the monomeric reactants, were added to produce films. Stability to various high energy radiations derived from lasers and other high energy radiation sources was tested. By comparison, the films containing the polydyes exhibit markedly shorter open-quotes burnthroughclose quotes times when employing a laser operating in the UV-Visible region. Addition of polydyes to materials then allow energy to be concentrated thus requiring lesser energy for fabrication of items such as computer chips and other electrical devices and miniaturization of items

  9. Synthesis of elastomeric polypropylene in bulk using C1-symmetric ansa-metallocenes. New aspects of the synthesis of 1-(fluoren-9-yl)-2-(2-methyl-5,6-dihydrocyclopenta[f]-1H-inden-1-yl)ethane and complexes of zirconium and hafnium with this ligand

    International Nuclear Information System (INIS)

    Nedorezova, P.M.; Veksler, Eh.N.; Novikova, E.S.; Optov, V.A.; Baranov, A.O.; Aladyshev, A.M.; Tsvetkova, V.I.; Shklyaruk, B.F.; Krut'ko, D.P.; Churakov, A.V.; Kuz'mina, L.G.; Howard, J.A.K.

    2005-01-01

    Isomeric 1-(fluoren-9-yl)-2-(2-methyl-5,6-dihydrocyclopenta[f]-1H-indenyl)ethanes (1a,b) and C 1 -symmetric metallocenes, viz., rac-{1-(η 5 -fluoren-9-yl)-2-(2-methyl-5,6-dihydrocyclopenta[f]- η 5 -inden-1-yl)ethane}zirconium dichloride (2) and rac-{1-(η 5 -fluoren-9-yl)- 2-(2-methyl-5,6-dihydrocyclopenta[f]-η 5 -inden-1-yl)ethane}hafnium dichloride (3), with these ligands were synthesized by modified procedures. The structures of compounds 1b (two crystalline modifications) and 3 were established by X-ray diffraction analysis. The synthesis of polypropylene in bulk was studied in the presence of polymethylalumoxane-activated metallocenes 2 and 3 in the temperature range of 30-70 deg C

  10. Developments of Chiral Metallocenes as Polymerization Catalysts

    Directory of Open Access Journals (Sweden)

    Takeshi Shiono

    2005-07-01

    Full Text Available This review article describes developments in chiral metallocenes as polymerization catalysts focusing on C2 symmetric ansa-zirconocene complexes. Selective synthesis of rac-isomers of ansa-zirconocenes are surveyed. Isospecific polymerizations of propylene catalyzed by chiral zirconocenes are summarized. Advanced series of polymerizations by chiral metallocenes such as asymmetric polymerization and polymerization of polar monomers are also introduced.

  11. Recent Advances of Metallocenes for Medicinal Chemistry.

    Science.gov (United States)

    Santos, Miguel M; Bastos, Pedro; Catela, Isabelle; Zalewska, Karolina; Branco, Luis C

    2017-01-01

    The recent advances for the synthesis and application of different metallocenes for Medicinal Chemistry is reviewed. This manuscript presents the different metallocene scaffolds, with special emphasis on ferrocene derivatives, and their potential pharmaceutical application. Over the last years, the synthesis of new metallocene compounds and their biological and medicinal effects against some types of diseases (e.g. anti-tumoral, antibiotics, anti-viral) have been reported. From the medicinal point of view, the attractive properties of metallocene derivatives, such as their high stability, low toxicity and appealing redox behaviors are particularly relevant. This area has attracted many researchers as well as the pharmaceutical industry due to the promising results of some metallocenes, in particular ferrocene compounds, in breast cancer and malaria. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  12. Metallocene Antimalarials: The Continuing Quest

    Science.gov (United States)

    Blackie, Margaret A. L.; Chibale, Kelly

    2008-01-01

    Over the last decade, a significant body of research has been developed around the inclusion of a metallocene moiety into known antimalarial compounds. Ferroquine is the most successful of these compounds. Herein, we describe our contribution to metallocene antimalarials. Our approach has sought to introduce diversity sites in the side chain of ferroquine in order to develop a series of ferroquine derivatives. The replacement of the ferrocenyl moiety with ruthenocene has given rise to ruthenoquine and a modest series of analogues. The reaction of ferroquine and selected analogues with Au(PPh3)NO3, Au(C6F5)(tht), and [Rh(COD)Cl2] has resulted in a series of heterobimetallic derivatives. In all cases, compounds have been evaluated for in vitro antiplasmodial activity in both chloroquine-sensitive and chloroquine-resistant strains of Plasmodium falciparum. Preliminary structure-activity relationships have been delineated. PMID:18274662

  13. Biochemistry of metallocenes. Pt. 2

    International Nuclear Information System (INIS)

    Wenzel, M.; Herken, R.; Klose, W.

    1977-01-01

    Metallocenes, labelled with 103 Ru, are potential radiopharmaceuticals for use in nuclear medicine diagnosis. Ruthenocene derivatives with oxopropene side-chains were administered to mice and rats to study their biochemical properties. Excretion rates and organ distributions of 103 RuCl 3 and Cinnamoyl-[ 103 Ru] ruthenocene were very different. While 103 RuCl 3 was relatively evenly distributed in the body, the metallocene derivative was concentrated in liver, lungs and spleen after intravenous (i.v.) injection. After i.p. injection, however, a high thymus affinity was observed and autoradiography proved that the site of 103 Ru accumulation was in thymocytes. The thymus affinity can be diminished by corticoid pretreatment and raised by inhibition of phagocytosis (BeSO 4 ). The mechanism of accumulation in the thymus and a possible clinical application are discussed. (orig.) [de

  14. Radium 223 dichloride for prostate cancer treatment

    Directory of Open Access Journals (Sweden)

    Deshayes E

    2017-09-01

    Full Text Available Emmanuel Deshayes,1,2 Mathieu Roumiguie,3 Constance Thibault,4 Philippe Beuzeboc,5 Florent Cachin,6 Christophe Hennequin,7 Damien Huglo,8 François Rozet,9 Diana Kassab-Chahmi,10 Xavier Rebillard,11 Nadine Houédé1,12 1Radiobiology Unit, INSERM U1194, Institut du Cancer de Montpellier (ICM, 2Department of Nuclear Medicine, Institut du Cancer de Montpellier (ICM, Montpellier, 3Urology Department, Andrology and Renal Transplantation, CHU Rangueil, Toulouse, 4Medical Oncology Department, Hôpital Européen Georges Pompidou, 5Oncology Department, Institut Curie, 6Department of Nuclear Medicine, CHU, Clermont-Ferrand, 7Radiotherapy Department, Hôpital Saint Louis, Paris, 8Department of Nuclear Medicine, CHRU, Lille, 9Urology Department, Institut Mutualiste Montsouris, 10Intergroupe coopérateur francophone de recherche en onco-urologie, Paris, 11Urology Department, Clinique BeauSoleil, Montpellier, 12Medical Oncology Department, Institut de Cancérologie du Gard – CHU Caremeau, Nîmes, France Abstract: Prostate cancer is the most common malignant disease in men. Several therapeutic agents have been approved during the last 10 years. Among them, radium-223 dichloride (Xofigo® is a radioactive isotope that induces irreversible DNA double-strand breaks and consequently tumor cell death. Radium-223 dichloride is a calcium-mimetic agent that specifically targets bone lesions. Radium-223 dichloride has been approved for the treatment of metastatic castration-resistant prostate cancer with symptomatic bone metastases, without known visceral metastases. In this review, first we summarize the interplay between prostate tumor cells and bone microenvironment; then, we discuss radium-223 dichloride mechanism of action and present the results of the available clinical trials and future developments for this new drug. Keywords: bone metastasis, mCRPC, mechanism, drug, agents, development 

  15. Ferromagnetism in metallocene-doped fullerenes

    CERN Document Server

    Mihailovic, D

    2003-01-01

    Ferromagnetism in fullerene-based systems doped with metallocenes is reviewed. These compounds form a ferromagnetic state by spin-coupling between pi electrons on fullerene units, while the metallocene molecules do not contribute to the spin ordering. One of these compounds has the highest critical temperature (19 K) for this class of compound. The magnetic properties of these materials are very strongly dependent on the crystallization conditions. Refs. 19 (author)

  16. Ferromagnetism in metallocene-doped fullerenes

    International Nuclear Information System (INIS)

    Mihailovic, D.

    2003-01-01

    Ferromagnetism in fullerene-based systems doped with metallocenes is reviewed. These compounds form a ferromagnetic state by spin-coupling between π electrons on fullerene units, while the metallocene molecules do not contribute to the spin ordering. One of these compounds has the highest critical temperature (19 K) for this class of compound. The magnetic properties of these materials are very strongly dependent on the crystallization conditions. Refs. 19 (author)

  17. Surface functionalization of detonation nanodiamonds by phosphonic dichloride derivatives.

    Science.gov (United States)

    Presti, Charlene; Alauzun, Johan G; Laurencin, Danielle; Mutin, P Hubert

    2014-08-05

    A new method for the functionalization of detonation nanodiamonds (DNDs) is proposed, on the basis of surface modification with phosphonic dichloride derivatives. DNDs were first modified by phenylphosphonic dichloride, and the grafting modes and hydrolytic stability under neutral conditions were investigated using (1)H, (13)C, and (31)P solid state NMR spectroscopy, Fourier transform infrared spectroscopy, as well as elemental analysis. Then, in order to illustrate the possibilities offered by this method, DNDs functionalized by mesityl imidazolium groups were obtained by postmodification of DNDs modified by 12-bromododecylphosphonic dichloride. The oxidative thermal stability of the functionalized DNDs was investigated using thermogravimetric analysis.

  18. Radiation exposure of relatives of patients treated with Ra-223 dichloride; Strahlenexposition von Angehoerigen bei Therapie mit Ra-223-Dichlorid

    Energy Technology Data Exchange (ETDEWEB)

    Wanke, C.; Szermerski, B.; Solle, A.; Geworski, L. [Medizinische Hochschule Hannover (Germany). Stabsstelle Strahlenschutz und Abt. Medizinische Physik; Pinkert, J. [Bayer Vital GmbH, Leverkusen (Germany); Kranert, W.T. [Frankfurt Univ. (Germany). Klinik fuer Nuklearmedizin; Andreeff, M. [Universitaetsklinikum ' ' Carl Gustav Carus' ' TU Dresden (Germany). Klinik fuer Nuklearmedizin

    2015-07-01

    Since November 2013, a radiopharmaceutical containing Ra-223 dichloride as active substance is approved in the European Union for patients with castration resistant prostate cancer with symptomatic bone metastases and no known visceral metastases. Ra-223 (T{sub 1/2} = 11.43 d) decays via a chain of 4 alpha and 2 beta decays. This therapy is presently the only application of an alpha emitter in clinical routine therapy. To show that the exposure of relatives and caregivers of patients treated with Ra-223 dichloride in an outpatient setting does not exceed a value of 1 mSv, the multicenter study ''RAPSODY'' was conducted. As Ra-223 and most of its progeny emit alpha particles, the internal exposure had to be evaluated in particular. Within this study, measurements of the radiation emitted from the patient were performed using standard dose-rate meters. Wipe-tests were taken in the patients' homes to identify significant contaminations and evaluated by liquid scintillation counting. Samples of saliva and sweat were taken and measured using gamma spectrometry. Ra-223 disintegrates to the noble gas Rn-219 and was measured in the exhaled breath from the patients using conventional Radon Monitors. Furthermore, a computational fluid dynamics simulation (CFD) was performed to assess the radioactivity in the air, which could be inhaled by persons close to the patient. Conclusions: The potential exposure of relatives and caregivers by external irradiation and incorporation of radioactivity exhaled or excreted by the patient with saliva or sweat is well below 1 mSv. No objections are seen regarding outpatient treatment. This paper summarizes contents of a poster presented at the Annual Meeting of the Society of Nuclear Medicine and Molecular Imaging.

  19. Synthesis of Substituted Titanocene Dichloride Derivatives by Hydrosilylation

    Czech Academy of Sciences Publication Activity Database

    Strašák, Tomáš; Karban, Jindřich; Červenková Šťastná, Lucie; Maixnerová, Lucie; Březinová, Anna; Bernard, Martin; Fajgar, Radek

    2014-01-01

    Roč. 768, OCT 1 (2014), s. 115-120 ISSN 0022-328X Institutional support: RVO:67985858 ; RVO:61388963 Keywords : titanocene dichloride * hydrosilylation * carbohydrates Subject RIV: CC - Organic Chemistry Impact factor: 2.173, year: 2014

  20. Electronic Structure of the d Bent-metallocene Cp(2)VCl(2): A Photoelectron and Density Functional Study.

    Science.gov (United States)

    Cranswick, Matthew A; Gruhn, Nadine E; Enemark, John H; Lichtenberger, Dennis L

    2008-04-15

    The Cp(2)VCl(2) molecule is a prototype for bent metallocene complexes with a single electron in the metal d shell, but experimental measure of the binding energy of the d electron by photoelectron spectroscopy eluded early attempts due to apparent decomposition in the spectrometer to Cp(2)VCl. With improved instrumentation, the amount of decomposition is reduced and subtraction of ionization intensity due to Cp(2)VCl from the Cp(2)VCl(2)/Cp(2)VCl mixed spectrum yields the Cp(2)VCl(2) spectrum exclusively. The measured ionization energies provide well-defined benchmarks for electronic structure calculations. Density functional calculations support the spectral interpretations and agree well with the ionization energy of the d(1) electron and the energies of the higher positive ion states of Cp(2)VCl(2). The calculations also account well for the trends to the other Group V bent metallocene dichlorides Cp(2)NbCl(2) and Cp(2)TaCl(2). The first ionization energy of Cp(2)VCl(2) is considerably greater than the first ionization energies of the second- and third-row transition metal analogues.

  1. Electronic Structure of the d1 Bent-metallocene Cp2VCl2: A Photoelectron and Density Functional Study

    Science.gov (United States)

    Cranswick, Matthew A.; Gruhn, Nadine E.; Enemark, John H.; Lichtenberger, Dennis L.

    2009-01-01

    The Cp2VCl2 molecule is a prototype for bent metallocene complexes with a single electron in the metal d shell, but experimental measure of the binding energy of the d electron by photoelectron spectroscopy eluded early attempts due to apparent decomposition in the spectrometer to Cp2VCl. With improved instrumentation, the amount of decomposition is reduced and subtraction of ionization intensity due to Cp2VCl from the Cp2VCl2/Cp2VCl mixed spectrum yields the Cp2VCl2 spectrum exclusively. The measured ionization energies provide well-defined benchmarks for electronic structure calculations. Density functional calculations support the spectral interpretations and agree well with the ionization energy of the d1 electron and the energies of the higher positive ion states of Cp2VCl2. The calculations also account well for the trends to the other Group V bent metallocene dichlorides Cp2NbCl2 and Cp2TaCl2. The first ionization energy of Cp2VCl2 is considerably greater than the first ionization energies of the second- and third-row transition metal analogues. PMID:19593395

  2. Planar chirale Metallocene

    OpenAIRE

    Kesselgruber, Martin

    2001-01-01

    The element of planar chirality turned out to be of special importance to achieve high enantioselectivities in various asymmetric processes. In the course of this PhD thesis, the sulfoximine unit was established as a new chiral ortho-directing group for ferrocenes. By variation of the metal fragment and other structural properties of a published chiral ligand, a cyclopentadienylrhenium(I)tricarbonyl complex was identified as more selective than the original ferrocene system in the asymmetric ...

  3. Water-Soluble Metallocene-Containing Polymers.

    Science.gov (United States)

    Alkan, Arda; Wurm, Frederik R

    2016-09-01

    Metallocenes are organometallic compounds with reversible redox profiles and tunable oxidation and reduction potentials, depending on the metal and substituents at the cyclopentadienyl rings. Metallocenes have been introduced in macromolecules to combine the redox-activity with polymer properties. There are many examples of such hydrophobic polymer materials, but much fewer water-soluble examples are found scattered across the polymer literature. However, in terms of drug delivery and other biological applications, water solubility is essential. For this very reason, all the synthetic routes to water-soluble metallocene containing polymers are collected and discussed here. The focus is on neutral ferrocene- and ruthenocene-containing and charged cobaltocenium-containing macromolecules (i.e., symmetrical sandwich complexes). The synthetic protocols, self-assembly behavior, and other benefits of the obtained materials are discussed. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Synthesis of Metallocene Catalyst for Terpolymerization of Ethylene, Propylene and Diene

    Directory of Open Access Journals (Sweden)

    S.M.M. Mortazavi

    2014-04-01

    Full Text Available The bis(indenyl zirconium dichloride catalyst was synthesized by a modified method at room temperature. Terpolymerization of ethylene, propylene and diene monomers were carried out using this metallocene catalyst under different conditions of different feed ratios of monomers, co-catalyst/catalyst ratios and polymerization temperatures. Methylaluminoxane (MAO was used as a co-catalyst. The highest activity of catalyst was obtained at total pressure 4 bar, co-catalyst/catalyst ratio [Al]/[Zr]=600, polymerization temperature 60°C and E/P=67:33 and momomer feed ratio of 1700 kgEPDM/molZrh. The activity of catalyst showed bell-shaped behaviors versus co-catalyst/catalyst ratio ([Al]/[Zr] and polymerization temperatures. The viscosity-average molecular weight (Mv of terpolymers increased with increasing total pressure at different feed ratios of monomers. However, the viscosity-average molecular weight of terpolymers decreased at higher co-catalyst/catalyst ratios ([Al]/[Zr] and higher polymerization temperatures. The increases in propylene and diene monomers in the feed ratios decreased the catalyst activity and viscosity-average molecular weight of terpolymers. The ratio of maximum average rate of terpolymerization to an average rate of terpolymerization at the end of the polymerization (DI for different terpolymerization conditions was relatively high; an indication of the decay kinetics for this type of metallocene catalyst. Increasing the co-catalyst/catalyst ratio up to [Al]/[Zr] = 500 increased the Et% and ENB% in the final obtained polymers. However, increasing the polymerization temperature, diene and propylene concentrations in the feed ratio decreased the Et% and increased the ENB% contents in the final obtained polymers. Tg of the final terpolymers was between -64 and -52°C. The study on microstructures of some polymer revealed block type of chain microstructures.

  5. Post-metallocene catalysts for olefin polymerisation

    International Nuclear Information System (INIS)

    Bryliakov, Konstantin P

    2007-01-01

    The main types of post-metallocene catalysts for olefin polymerisation based on bis(imino), bis(imino)pyridyl, bis(phenoxyimino), bis(pyrrolylimino) and other complexes of transition metals developed in the last 10-15 years and having prospects for practical use are considered. Modern views on the mechanism of action of these catalysts are discussed.

  6. Post-metallocene catalysts for olefin polymerisation

    Energy Technology Data Exchange (ETDEWEB)

    Bryliakov, Konstantin P [G K Boreskov Institute of Catalysis, Siberian Branch of the Russian Academy of Sciences (Russian Federation)

    2007-03-31

    The main types of post-metallocene catalysts for olefin polymerisation based on bis(imino), bis(imino)pyridyl, bis(phenoxyimino), bis(pyrrolylimino) and other complexes of transition metals developed in the last 10-15 years and having prospects for practical use are considered. Modern views on the mechanism of action of these catalysts are discussed.

  7. Metallocene catalyst containing bulky organic group

    Energy Technology Data Exchange (ETDEWEB)

    Marks, Tobin J. (Evanston, IL); Ja, Li (Chicago, IL); Yang, Xinmin (Evanston, IL)

    1996-03-26

    An ionic metallocene catalyst for olefin polymerization which comprises: (1) a cyclopentadienyl-type ligand, a Group IVB transition metal, and alkyl, aryl, or hydride substituents, as a cation, and (2) a weakly coordinating anion comprising boron substituted with halogenated, such as tetra fluoro, aryl substituents preferably containing silylalkyl substitution, such as para-silyl t-butyldimethyl.

  8. Metallocene catalyst containing bulky organic group

    Science.gov (United States)

    Marks, T.J.; Ja, L.; Yang, X.

    1996-03-26

    An ionic metallocene catalyst for olefin polymerization which comprises: (1) a cyclopentadienyl-type ligand, a Group IVB transition metal, and alkyl, aryl, or hydride substituents, as a cation, and (2) a weakly coordinating anion comprising boron substituted with halogenated, such as tetrafluoro-aryl substituents preferably containing silylalkyl substitution, such as para-silyl t-butyldimethyl.

  9. Post-metallocene catalysts for olefin polymerisation

    Science.gov (United States)

    Bryliakov, Konstantin P.

    2007-03-01

    The main types of post-metallocene catalysts for olefin polymerisation based on bis(imino), bis(imino)pyridyl, bis(phenoxyimino), bis(pyrrolylimino) and other complexes of transition metals developed in the last 10-15 years and having prospects for practical use are considered. Modern views on the mechanism of action of these catalysts are discussed.

  10. Hydrogen and chlorine isotope exchange in hydrogen dichloride ions

    International Nuclear Information System (INIS)

    Szydlowski, J.; Ratajska, W.

    1987-01-01

    The kinetics of deuterium and chlorine-36 isotope exchange between hydrogen dichloride ions in tetramethyl- and tetraethyl-ammonium salts and hydrogen chloride was studied in the temperature range of 275-304 K. On the basis of the results obtained the exchange mechanism was proposed emphasizing the role of hydrogen bonding in the exchange process. (author)

  11. a review of cyclopentadienyl type ligands in group 4 metallocene

    African Journals Online (AJOL)

    Neil Grimmer

    4. TiCl. Cl. 3. M. M=Ti 1. =Zr 2. Cl. Cl. 2. The Nature of Metallocene Catalysts. Before we commence the discussion of how metallocene ligand design has evolved, .... The use of kinetic isotope effects to probe the polymerisation mechanism, first ...... Here the size of a ligand is measured as a function of distance from the point.

  12. Sterically shielded diboron-containing metallocene olefin polymerization catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Marks, T.J.; Ja, L.; Yang, X.

    1995-09-05

    A non-coordinating anion, preferably containing a sterically shielded diboron hydride, if combined with a cyclopenta-dienyl-substituted metallocene cation component, such as a zirconocene metallocene, is a useful olefin polymerization catalyst component. The anion preferably has the formula as shown in the accompanying diagram where R is branched lower alkyl, such as t-butyl.

  13. Sterically shielded diboron-containing metallocene olefin polymerization catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Marks, Tobin J. (Evanston, IL); Ja, Li (Chicago, IL); Yang, Xinmin (Evanston, IL)

    1995-09-05

    A non-coordinating anion, preferably containing a sterically shielded diboron hydride, if combined with a cyclopenta-dienyl-substituted metallocene cation component, such as a zirconocene metallocene, is a useful olefin polymerization catalyst component. The anion preferably has the formula ##STR1## where R is branched lower alkyl, such as t-butyl.

  14. Analytical rheology of metallocene-catalyzed polyethylenes

    Science.gov (United States)

    Shanbhag, Sachin; Takeh, Arsia

    2011-03-01

    A computational algorithm that seeks to invert the linear viscoelastic spectrum of single-site metallocene-catalyzed polyethylenes is presented. The algorithm uses a general linear rheological model of branched polymers as its underlying engine, and is based on a Bayesian formulation that transforms the inverse problem into a sampling problem. Given experimental rheological data on unknown single-site metallocene- catalyzed polyethylenes, it is able to quantitatively describe the range of values of weight-averaged molecular molecular weight, MW , and average branching density, bm , consistent with the data. The algorithm uses a Markov-chain Monte Carlo method to simulate the sampling problem. If, and when information about the molecular weight is available through supplementary experiments, such as chromatography or light scattering, it can easily be incorporated into the algorithm, as demonstrated. Financial support from NSF DMR 0953002.

  15. Quantum transport of the single metallocene molecule

    Science.gov (United States)

    Yu, Jing-Xin; Chang, Jing; Wei, Rong-Kai; Liu, Xiu-Ying; Li, Xiao-Dong

    2016-10-01

    The Quantum transport of three single metallocene molecule is investigated by performing theoretical calculations using the non-equilibrium Green's function method combined with density functional theory. We find that the three metallocen molecules structure become stretched along the transport direction, the distance between two Cp rings longer than the other theory and experiment results. The lager conductance is found in nickelocene molecule, the main transmission channel is the electron coupling between molecule and the electrodes is through the Ni dxz and dyz orbitals and the s, dxz, dyz of gold. This is also confirmed by the highest occupied molecular orbital resonance at Fermi level. In addition, negative differential resistance effect is found in the ferrocene, cobaltocene molecules, this is also closely related with the evolution of the transmission spectrum under applied bias.

  16. Stereospecific olefin polymerization with chiral metallocene catalysts

    OpenAIRE

    Brintzinger, Hans-Herbert; Fischer, David; Mülhaupt, Rolf; Rieger, Bernhard; Waymouth, Robert M.

    1995-01-01

    Current studies on novel, metallocenebased catalysts for the polymerization of α-olefins have far-reaching implications for the development of new materials as well as for the understanding of basic reaction mechanisms responsible for the growth of a polymer chain at a catalyst center and the control of its stereoregularity. In contrast to heterogeneous Ziegler–Natta catalysts, polymerization by a homogeneous, metallocene-based catalyst occurs principally at a single type of metal center with...

  17. Metallocene-catalyzed ethylene−α-olefin isomeric copolymerization: A perspective from hydrodynamic boundary layer mass transfer and design of MAO anion

    KAUST Repository

    Adamu, Sagir

    2015-11-28

    This study reports a novel conceptual framework that can be easily experimented to evaluate the effects of hydrodynamic boundary layer mass transfer, methylaluminoxane (MAO) anion design, and comonomer steric hindrance on metallocene-catalyzed ethylene polymerization. This approach was illustrated by conducting homo- and isomeric copolymerization of ethylene with 1-hexene and 4-methyl-1-pentene in the presence of bis(n-butylcyclopentadienyl) zirconium dichloride (nBuCp)2ZrCl2, using (i) MAO anion 1 (unsupported [MAOCl2]−) and pseudo-homogeneous reference polymerization, and (ii) MAO anion 2 (supported Si−O−[MAOCl2]−) and in-situ heterogeneous polymerization. The measured polymer morphology, catalyst productivity, molecular weight distribution, and inter-chain composition distribution were related to the locus of polymerization, comonomer effect, in-situ chain transfer process, and micromixing effect, respectively. The peak melting and crystallization temperatures and %crystallinity were mathematically correlated to the parameters of microstructural composition distributions, melt fractionation temperatures, and average lamellar thickness. These relations showed to be insightful. The comonomer-induced enchainment defects and the eventual partial disruption of the crystal lattice were successfully modeled using Flory and Gibbs–Thompson equations. The present methodology can also be applied to study ethylene−α-olefin copolymerization, performed using MAO-activated non-metallocene precatalysts.

  18. Reaction of metallocene dichlorides of titanium(IV) and zirconium(IV) and lithium bis(trimethylsilyl)amide

    Energy Technology Data Exchange (ETDEWEB)

    Simpson, S.J.; Andersen, R.A.

    1981-11-01

    Reaction of Cp/sub 2/TiCl/sub 2/ with 1 or 2 molar equiv of LiN(SiMe/sub 3/)/sub 2/ yields the previously described metallacycle Cp/sub 2/TiCH/sub 2/SiMe/sub 2/NSiMe/sub 3/. Mass balance shows that for each mole of metallacycle formed, 1 molar equiv of hydrogen chloride is also formed. The related zirconium metallacycle was prepared from Cp/sub 2/Zr(H)(Cl) and LiN(SiMe/sub 3/)/sub 2/. The bis(silylamide) of zirconium, Cp/sub 2/Zr(N(SiMe/sub 3/)/sub 2/)/sub 2/, was prepared from Cp/sub 2/ZrCl/sub 2/ and 2 molar equiv of LiN(SiMe/sub 3/)/sub 2/. The Me/sub 3/Si groups in the latter compound are magnetically nonequivalent at 27/sup 0/C but coalesce at 84/sup 0/C on the /sup 1/H NMR time scale.

  19. Cyanide metallocenes of trivalent f-elements

    International Nuclear Information System (INIS)

    Maynadie, J.; Berthet, J.C.; Thuery, P.; Ephritikhine, M.

    2007-01-01

    Addition of N n Bu 4 CN to (C 5 Me 5 ) 2 UI(py), (C 5 Me 5 ) 2 CeI, or (C 5 Me 5 ) 2 M(OTf) (M = U, Ce) in acetonitrile led to the precipitation of the neutral mono-cyanide species [(C 5 Me 5 ) 2 M(μ-CN)] n [M = U (1), Ce (2)], which likely have an oligomeric structure, as shown by the tri-meric cyanide-bridged complex [(C 5 Me 5 ) 2 Ce(μ-CN)(CN t Bu)] 3 (3) obtained by addition of excess t BuNC into a suspension of 2 in acetonitrile. The structure of the U(III,IV) mixed valence compound [{(C 5 Me 5 ) 2 U} 2 (μ-CN){(μ-CN) 2 Na(thf)} 2 ] ∞ (4), which crystallized from a thf solution of (C 5 Me 5 ) 2 UI(py) in the presence of excess NaCN, reveals a unique example of an f-element-(μ-CN)-M interaction (M = main group or d transition metal). The anionic poly-cyanides [(C 5 Me 5 ) 2 M(CN) 3 ][N n Bu 4 ] 2 [M = U (5), Ce (6)] were synthesized by treatment of 1 and 2 with 2 equiv or an excess of N n Bu 4 CN in acetonitrile; they were also prepared in a one-pot procedure by stepwise addition of 1 equiv of KCN and 2 equiv of N n Bu 4 CN to the parent iodides in acetonitrile. The bent metallocenes 5 and 6 are unique low-valent molecular poly-cyanide compounds of an f-element that have been structurally identified, while 5 is the first fully characterized actinide(III) cyanide. Comparison of the crystal structures of 5 and 6 shows that the M-C(C 5 Me 5 ) and M-C(CN) distances are 0.02-0.03 Angstroms shorter for M = U than for M Ce, while the ionic radius of uranium(III) is 0.02 Angstroms larger than that of cerium(III). (authors)

  20. Organo-Lewis acid as cocatalyst for cationic homogenous metallocene Ziegler-Natta olefin polymerizations

    Energy Technology Data Exchange (ETDEWEB)

    Marks, Tobin J. (Evanston, IL); Chen, You-Xian (Chicago, IL)

    2000-01-01

    The synthesis of the organo-Lewis acid perfluorobiphenylborane (PBB) and the activation of metallocenes for the formation of a variety of highly active homogeneous Ziegler-Natta metallocene olefin polymerization, copolymerization and ring-opening polymerization catalysts is described.

  1. Non-metallocene organometallic complexes and related methods and systems

    Energy Technology Data Exchange (ETDEWEB)

    Agapie, Theodor (Berkeley, CA); Golisz, Suzanne Rose (Pasadena, CA); Tofan, Daniel (Pasadena, CA); Bercaw, John E. (Pasadena, CA)

    2010-12-07

    A non-metallocene organometallic complex comprising a tridentate ligand and a metal bonded to a tridentate ligand, wherein two substituted aryl groups in the tridentate ligand are connected to a cyclic group at the ortho position via semi-rigid ring-ring linkages, and selected so to provide the resulting non-metallocene organometallic complex with a C.sub.S geometry, a C.sub.1 geometry, a C.sub.2 geometry or a C.sub.2v geometry. Method for performing olefin polymerization with a non-metallocene organometallic complex as a catalyst, related catalytic systems, tridentate ligand and method for providing a non-metallocene organometallic complex.

  2. Hafnium metallocene catalyst for the polymerization of olefins

    Energy Technology Data Exchange (ETDEWEB)

    Ewen, J.A.

    1988-12-27

    A catalyst is described for the polymerization and copolymerization of olefins comprising a an alumoxane and chiral, stereorigid hafnium metallocene catalyst. It includes a cyclopentadienyl ring and germanium, silicon, phosphorus, nitrogen, boron, and aluminum radicals.

  3. Metallocene to metallocene conversion. Synthesis of an oxazoline-substituted pentamethyliridocenium cation from a ferrocenyloxazoline.

    Science.gov (United States)

    Arthurs, Ross A; Horton, Peter N; Coles, Simon J; Richards, Christopher J

    2016-05-19

    Reaction of (S)-2-ferrocenyl-4-(1-methylethyl)oxazoline with [Cp*IrCl2]2 in benzonitrile with KPF6 and NaOH gave (η(5)-(S)-2-(4-(1-methylethyl))oxazolinylcyclopentadienyl)(η(5)-pentamethylcyclopentadienyl)iridium(iii) hexafluorophosphate (68%). This transformation of an iron-based into an iridium-based metallocene proceeds via the rearrangement, with loss of cyclopentadienyliron, of an intermediate cationic ferrocenyliridacycle.

  4. Synthesis of [119mSn]-mesoporphyrin IX dichloride

    International Nuclear Information System (INIS)

    Denissen, J.F.

    1990-01-01

    Tin mesoporphyrin IX dichloride (Sn-MPCl 2 ) is a heme oxygenase inhibitor of current clinical interest for the treatment of neonatal hyperbilirubinemia. The synthesis of [ 119m Sn]-MPCl 2 for drug metabolism and disposition studies is reported. [ 119m Sn]-MPCl 2 was prepared in 60% radiochemical yield by metalation of the porphyrin nucleus of mesoporphyrin IX dihydrochloride with tin(II)-119m acetate. The product had a specific activity of 43.4 mCi/mmol and a radiochemical purity of 99%, as determined by radio-HPLC analysis. (author)

  5. Synthesis and insertion chemistry of mixed tether uranium metallocene complexes.

    Science.gov (United States)

    Siladke, Nathan A; LeDuc, Jennifer; Ziller, Joseph W; Evans, William J

    2012-11-12

    The synthesis of mixed tethered alkyl uranium metallocenes has been investigated by examining the reactivity of the bis(tethered alkyl) metallocene [(η(5)-C(5)Me(4)SiMe(2)CH(2)-κC)(2)U] (1) with substrates that react with only one of the U-C linkages. The effect of these mixed tether coordination environments on the reactivity of the remaining U-C bond has been studied by using CO insertion chemistry. One equivalent of azidoadamantane (AdN(3)) reacts with 1 to yield the mixed tethered alkyl triazenido complex [(η(5)-C(5)Me(4)SiMe(2)CH(2)-κC)U(η(5)-C(5)Me(4)SiMe(2)-CH(2)NNN-Ad-κ(2)N(1,3))]. Similarly, a single equivalent of CS(2) reacts with 1 to form the mixed tethered alkyl dithiocarboxylate complex [(η(5)-C(5)Me(4)SiMe(2)CH(2)-κC)U(η(5)-C(5)Me(4)SiMe(2)-CH(2)C(S)(2)-κ(2)S,S')], a reaction that constitutes the first example of CS(2) insertion into a U(4+)-C bond. Complex 1 reacts with one equivalent of pyridine N-oxide by C-H bond activation of the pyridine ring to form a mixed tethered alkyl cyclometalated pyridine N-oxide complex [(η(5)-C(5)Me(4)SiMe(2)CH(2)-κC)(η(5)-C(5)Me(4)SiMe(3))U(C(6)H(4)NO-κ(2)C,O)]. The remaining (η(5)-C(5)Me(4)SiMe(2)CH(2)-κC)(2-) ligand in each of these mixed tethered species show reactivity towards CO and tethered enolate ligands form by insertion. Subsequent rearrangement have been identified in [(η(5)-C(5)Me(4)SiMe(3))U(C(5)H(4)NO-κ(2)C,O)(η(5)-C(5)Me(4)SiMe(2)C(=CH(2))O-κO)] and [(η(5)-C(5)Me(4)SiMe(2)CH(2)NNN-Ad-κ(2)N(1,3))U(η(5)-C(5)Me(4)SiMe(2)C(=CH(2))O-κO)]. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Synthesis and insertion chemistry of mixed tether uranium metallocene complexes

    International Nuclear Information System (INIS)

    Siladke, Nathan A.; LeDuc, Jennifer; Ziller, Joseph W.; Evans, William J.

    2012-01-01

    The synthesis of mixed tethered alkyl uranium metallocenes has been investigated by examining the reactivity of the bis(tethered alkyl) metallocene [(η 5 -C 5 Me 4 SiMe 2 CH 2 -κC) 2 U] (1) with substrates that react with only one of the U-C linkages. The effect of these mixed tether coordination environments on the reactivity of the remaining U-C bond has been studied by using CO insertion chemistry. One equivalent of azidoadamantane (AdN 3 ) reacts with 1 to yield the mixed tethered alkyl triazenido complex [(η 5 -C 5 Me 4 SiMe 2 CH 2 -κC)U(η 5 -C 5 Me 4 SiMe 2 -CH 2 NNN-Ad-κ 2 N 1,3 )]. Similarly, a single equivalent of CS 2 reacts with 1 to form the mixed tethered alkyl dithiocarboxylate complex [(η 5 -C 5 Me 4 SiMe 2 CH 2 -κC)U(η 5 -C 5 Me 4 SiMe 2 - CH 2 C(S) 2 -κ 2 S,S ' )], a reaction that constitutes the first example of CS 2 insertion into a U 4+ -C bond. Complex 1 reacts with one equivalent of pyridine N-oxide by C-H bond activation of the pyridine ring to form a mixed tethered alkyl cyclometalated pyridine N-oxide complex [(η 5 -C 5 Me 4 SiMe 2 CH 2 -κC)(η 5 -C 5 Me 4 SiMe 3 )U(C 6 H 4 NO-κ 2 C,O)]. The remaining (η 5 -C 5 Me 4 SiMe 2 CH 2 -κC) 2- ligand in each of these mixed tethered species show reactivity towards CO and tethered enolate ligands form by insertion. Subsequent rearrangement have been identified in [(η 5 -C 5 Me 4 SiMe 3 )U(C 5 H 4 NO-κ 2 C,O)(η 5 -C 5 Me 4 SiMe 2 C(=CH 2 )O- κO)] and [(η 5 -C 5 Me 4 SiMe 2 CH 2 NNN-Ad-κ 2 N 1,3 )U(η 5 -C 5 Me 4 SiMe 2 C(=CH 2 )O-κO)]. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  7. Synthesis and Biological Evaluation of Achiral Indole-Substituted Titanocene Dichloride Derivatives

    Directory of Open Access Journals (Sweden)

    Anthony Deally

    2012-01-01

    Full Text Available Six new titanocene compounds have been isolated and characterised. These compounds were synthesised from their fulvene precursors using Super Hydride (LiBEt3H followed by transmetallation with titanium tetrachloride to yield the corresponding titanocene dichloride derivatives. These complexes are bis-[((1-methyl-3-diethylaminomethylindol-2-ylmethylcyclopentadienyl] titanium (IV dichloride (5a, bis-[((5-methoxy-1-methyl,3-diethylaminomethylindol-2-ylmethylcyclopentadienyl] titanium (IV dichloride (5b, bis-[((1-methyl,3-diethylaminomethylindol-4-ylmethylcyclopentadienyl] titanium (IV dichloride (5c, bis-[((5-bromo-1-methylindol-3-ylmethylcyclopentadienyl] titanium (IV dichloride (5d, bis-[((5-chloro-1-methylindol-3-ylmethylcyclopentadienyl] titanium (IV dichloride (5e, and bis-[((5-fluoro-1-methylindol-3-ylmethylcyclopentadienyl] titanium (IV dichloride (5f. All six titanocenes 5a–5f were tested for their cytotoxicity through MTT-based in vitro tests on CAKI-1 cell lines using DMSO and Soluphor P as solubilising agents in order to determine their IC50 values. Titanocenes 5a–5f were found to have IC50 values of 10 (±2, 21 (±3, 29 (±4, 140 (±6, and 450 (±10 μM when tested using DMSO.

  8. Radiation exposure of relatives of patients treated with Ra-223 dichloride

    International Nuclear Information System (INIS)

    Wanke, C.; Szermerski, B.; Solle, A.; Geworski, L.; Kranert, W.T.; Andreeff, M.; TU Dresden

    2015-01-01

    Since November 2013, a radiopharmaceutical containing Ra-223 dichloride as active substance is approved in the European Union for patients with castration resistant prostate cancer with symptomatic bone metastases and no known visceral metastases. Ra-223 (T 1/2 = 11.43 d) decays via a chain of 4 alpha and 2 beta decays. This therapy is presently the only application of an alpha emitter in clinical routine therapy. To show that the exposure of relatives and caregivers of patients treated with Ra-223 dichloride in an outpatient setting does not exceed a value of 1 mSv, the multicenter study ''RAPSODY'' was conducted. As Ra-223 and most of its progeny emit alpha particles, the internal exposure had to be evaluated in particular. Within this study, measurements of the radiation emitted from the patient were performed using standard dose-rate meters. Wipe-tests were taken in the patients' homes to identify significant contaminations and evaluated by liquid scintillation counting. Samples of saliva and sweat were taken and measured using gamma spectrometry. Ra-223 disintegrates to the noble gas Rn-219 and was measured in the exhaled breath from the patients using conventional Radon Monitors. Furthermore, a computational fluid dynamics simulation (CFD) was performed to assess the radioactivity in the air, which could be inhaled by persons close to the patient. Conclusions: The potential exposure of relatives and caregivers by external irradiation and incorporation of radioactivity exhaled or excreted by the patient with saliva or sweat is well below 1 mSv. No objections are seen regarding outpatient treatment. This paper summarizes contents of a poster presented at the Annual Meeting of the Society of Nuclear Medicine and Molecular Imaging.

  9. The adsorption of Benzene-Ethylene Dichloride Mixtures on Activated Carbon

    Science.gov (United States)

    Miao, T.; Tang, H. M.; Cheng, Z. X.

    2018-02-01

    The single component adsorption of benzene and ethylene dichloride and also the adsorption of binary mixtures of benzene and ethylene dichloride have been studied in a small fixed isothermal bed containing activated carbon (AC). Results indicate that an empirical Langmuir isotherm fits the experimental data for single components. An extended form of the empirical Langmuir isotherm, in which the parameters are obtained from single component data, satisfactorily describes the adsorption of binary mixtures. Breakthrough curves of both components could be predicted with good precision studied. This paper analyses the adsorption behaviour of a mixture of VOCs (benzene–ethylene dichloride) on AC, due to the lack of information regarding the adsorption of mixtures.

  10. Development of syndiotactic PP technology using metallocene catalyst. Metallocene shokubai wo mochiita syndiotactic PP no gijutsu kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    Uchikawa, N. (Mitsui Toatsu Chemicals, Inc., Tokyo (Japan))

    1993-09-01

    This paper introduces a metallocene catalyst and syndiotactic PP synthesized therefrom. The metallocene catalyst discovered in 1980 is a combination of metallocene compound of the IV-family transition metal with methyl aluminoxane (MAO) as a promoter. The metallocene catalyst has its active species homogeneous and soluble to solvents, hence it is called a homogeneous-system polymerized catalyst. Further, its active species concentration is said to account for 65% or higher of the transition metal at normal temperatures, and has high polymerization activity and superior random copolymerization performance. A syndiotactic PP having high stereoregularity and macromolecules sufficient in amount as molding resin was synthesized in 1988 by using a combination of the metallocene catalyst with MAO. It has properties of crystallinity from 30% to 40%, a melting point in a range from 140[degree]C to 150[degree]C, and a density of 0.88. It has high normal-temperature impact strength, low bending elastic modulus, and high transparency, and is expected to develop into foodstuff and medical material packaging materials. 4 figs., 3 tabs.

  11. The quenching of excited uranyl ion by d6 metallocenes

    International Nuclear Information System (INIS)

    Traverso, O.; Rossi, R.; Magon, L.; Cinquantini, A.; Kemp, T.

    1978-01-01

    Quenching constants Ksub(Q) of uranyl luminescence by d 6 metallocenes of Fe, Ru, and Os have been obtained both from luminescence intensity and lifetime measurements. The values of log 10 Ksub(Q) are correlated with the oxidant potentials of metallocenes, in accordance with an electron-transfer mechanism. This scheme is supported by photoreaction studies, where the formation of either the rather elusive [UO 2 ] + ion or (in the case of osmocene solutions) uranium(IV) species has been observed: in the case of ferrocene solutions, ferricenium ion is also produced. (author)

  12. Metallocene Catalytic Insertion Polymerization of 1-Silene to Polycarbosilanes

    Science.gov (United States)

    Tian, Yuelong; Ge, Min; Zhang, Weigang; Lv, Xiaoxu; Yu, Shouquan

    2015-11-01

    Metallocene of zirconium were used as a catalyst for an insertion polymerization of 1-methylsilene directly into pre-ceramic precursor polyzirconocenecarbosilane (PZCS) during dechlorination of dichlorodimethylesilane by sodium, which exhibits high catalytic effectiveness with the maximum conversion ratio of polycarbosilane up to 91%. The average molecular weights of polymers synthesized are less than 1400, all with very narrow polymolecularities. The mechanism of catalytic polymerization was assumed to be similar to a coordination insertion polymerization of 1-olefins by metallocenes. The obtained PZCS show high ceramic yields with formation of composite ceramics of ZrC-SiC, which are novel polymeric precursors of ultra-high temperature ceramic (UHTC) fiber and composite.

  13. Group 4 metallocene catalysed full dehydrogenation of hydrazine borane.

    Science.gov (United States)

    Thomas, Johannes; Klahn, Marcus; Spannenberg, Anke; Beweries, Torsten

    2013-10-01

    A study of the full dehydrogenation of hydrazine borane (H2N-NH2·BH3) to give H2 and N2 as gaseous products catalysed by a variety of group 4 metallocene alkyne complexes of the type CpM(L)(η(2)-Me3SiC2SiMe3) (Cp' = substituted or unsubstituted η(5)-cyclopentadienyl; M = Ti, no L; M = Zr, L = pyridine) and group 4 metallocene hydrides is presented. Volumetric data show that the amount of hydrogen released is strongly dependent on both, the metal and the cyclopentadienyl ligand.

  14. Adenosine triphosphate-magnesium dichloride during hyperdynamic porcine endotoxemia: Effects on hepatosplanchnic oxygen exchange and metabolism

    NARCIS (Netherlands)

    Asfar, Pierre; Nalos, Marek; Pittner, Antje; Theisen, Marc; Ichai, Carole; Ploner, Franz; Georgieff, Michael; Ince, Can; Brückner, Uwe Bernd; Leverve, Xavier Maurice; Radermacher, Peter; Froeba, Gebhard

    2002-01-01

    OBJECTIVE: To assess the effects of adenosine triphosphate-magnesium dichloride (ATP-MgCl2) on systemic and hepatosplanchnic hemodynamics, oxygen exchange, and energy metabolism over 24 hrs of hyperdynamic normotensive porcine endotoxemia. DESIGN: Prospective, randomized, controlled experimental

  15. Crystal structure of magnesium dichloride decahydrate determined by X-ray and neutron diffraction under high pressure.

    Science.gov (United States)

    Komatsu, Kazuki; Shinozaki, Ayako; Machida, Shinichi; Matsubayashi, Takuto; Watanabe, Mao; Kagi, Hiroyuki; Sano-Furukawa, Asami; Hattori, Takanori

    2015-02-01

    Magnesium dichloride decahydrate (MgCl2·10H2O) and its deuterated counterpart (MgCl2·10D2O) are identified for the first time by in-situ powder synchrotron X-ray and spallation neutron diffraction. These substances are crystallized from a previously unidentified nanocrystalline compound, which originates from an amorphous state at low temperature. A combination of a recently developed autoindexing procedure and the charge-flipping method reveals that the crystal structure of MgCl2·10H2O consists of an ABCABC··· sequence of Mg(H2O)6 octahedra. The Cl(-) anions and remaining water molecules unconnected to the Mg(2+) cations bind the octahedra, similar to other water-rich magnesium dichloride hydrates. The D positions in MgCl2·10D2O, determined by the difference Fourier methods using the neutron powder diffraction patterns at 2.5 GPa, show the features such as bifurcated hydrogen bonds and tetrahedrally coordinated O atoms, which were not found in other forms of magnesium chloride hydrates.

  16. Polypropylene reinvented: Costs of using metallocene catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Brockmeier, N.F.

    1996-05-01

    This study develops scoping estimates of the required capital investment and manufacturing costs to make a zirconocene catalyst/cocatalyst system [(F{sub 6}-acen)Zr(CH{sub 2}CMe{sub 3})(NMe{sub 2}Ph)][B(C{sub 6}F{sub 5}){sub 4}] immobilized on a silica support. Costs for this fluorine-based system are compared with estimates for two other metallocene catalysts using methylaluminoxane (MAO)-based cocatalysts. Including wt of support and cocatalyst, each of the production facilities for making the 3 zirconocene catalyst systems is sized at 364--484 tonnes/year. Cost to make the F-based catalyst system is estimated to be $10780/kg, assuming 20% return on capital invested. Costs for the two MAO-based catalyst system fall in the range of $10950--12160/kg, assuming same return. Within the {plus_minus}50% accuracy of these estimates, these differences are not significant. Given a catalyst productivity of 250 kg resin/gram zirconocene, the cost contribution in the finished ethylene-propylene copolymer resin is 4.4 cents/kg, excluding selling, administrative, research costs.

  17. An approach to study 'molecular rocket' reaction using metallocene-cyclodextrin inclusion compounds

    International Nuclear Information System (INIS)

    Matsue, H.; Sekine, T.; Yoshihara, K.

    1992-01-01

    A 'molecular rocket' using nuclear recoil in metallocene inclusion complex has been studied. Sublimatographic separation of liberated metallocene molecule from metallocene cyclodextrin complex suggested that at least a small fraction was due to this molecular rocket process with soft landing, which causes no serious decomposition. In the retention-recoil energy relation, analysis also revealed a part which suggested the presence of the molecular rocket with and without decomposition. (author) 11 refs.; 3 figs.; 1 tab

  18. 129I Moessbauer spectroscopic study of metallocene-iodine adducts

    International Nuclear Information System (INIS)

    Nakashima, Satoru; Sakai, Hiroshi; Watanabe, Masanobu; Maeda, Yutaka

    1994-01-01

    A 129 I Moessbauer spectroscopic study of iodine adducts of ferrocenophane, biruthenocene, and osmocene is reported. The spectra show the existence of iodine bonded to the central metals of metallocenes in addition to triiodide anions. The valence state of iron in the ferrocenophane-iodine adduct is the same as those of ruthenium and osmium in their adducts. (orig.)

  19. A bipyridyl thorium metallocene: synthesis, structure and reactivity.

    Science.gov (United States)

    Ren, Wenshan; Song, Haibin; Zi, Guofu; Walter, Marc D

    2012-05-21

    The synthesis, structure and reactivity of a new bipy thorium metallocene have been studied. The reduction of the thorium chloride metallocene [η(5)-1,3-(Me(3)C)(2)C(5)H(3)](2)ThCl(2) (1) with potassium graphite in the presence of 2,2'-bipyridine gives the purple bipy metallocene [η(5)-1,3-(Me(3)C)(2)C(5)H(3)](2)Th(bipy) (2) in good yield. Complex 2 has been fully characterized by various spectroscopic techniques, elemental analysis and X-ray diffraction analysis. Complex 2 reacts cleanly with trityl chloride, silver halides and diphenyl diselenide, leading to the halide metallocenes [η(5)-1,3-(Me(3)C)(2)C(5)H(3)](2)ThX(2) (X = Cl (1), Br (3), I (4)) and [η(5)-1,3-(Me(3)C)(2)C(5)H(3)](2)Th(F)(μ-F)(3)Th[η(5)-1,3-(Me(3)C)(2)C(5)H(3)](F)(bipy) (5), and selenido metallocene [η(5)-1,3-(Me(3)C)(2)C(5)H(3)](2)Th(SePh)(2) (6), in good conversions. In addition, 2 cleaves the C[double bond, length as m-dash]S bond of CS(2) to give the sulfido complex, [η(5)-1,3-(Me(3)C)(2)C(5)H(3)](2)ThS (7), which further undergoes an irreversible dimerization or nucleophilic addition with CS(2), leading to the dimeric sulfido complex {[η(5)-1,3-(Me(3)C)(2)C(5)H(3)](2)Th}(μ-S)(2) (8) and dimeric trithiocarbonate complex {[η(5)-1,3-(Me(3)C)(2)C(5)H(3)](2)Th}(μ-CS(3))(2) (10) in good yields, respectively.

  20. Synthesis and insertion chemistry of mixed tether uranium metallocene complexes

    Energy Technology Data Exchange (ETDEWEB)

    Siladke, Nathan A.; LeDuc, Jennifer; Ziller, Joseph W.; Evans, William J. [Department of Chemistry, University of California, Irvine, CA (United States)

    2012-11-12

    The synthesis of mixed tethered alkyl uranium metallocenes has been investigated by examining the reactivity of the bis(tethered alkyl) metallocene [(η{sup 5}-C{sub 5}Me{sub 4}SiMe{sub 2}CH{sub 2}-κC){sub 2}U] (1) with substrates that react with only one of the U-C linkages. The effect of these mixed tether coordination environments on the reactivity of the remaining U-C bond has been studied by using CO insertion chemistry. One equivalent of azidoadamantane (AdN{sub 3}) reacts with 1 to yield the mixed tethered alkyl triazenido complex [(η{sup 5}-C{sub 5}Me{sub 4}SiMe{sub 2}CH{sub 2}-κC)U(η{sup 5}-C{sub 5}Me{sub 4}SiMe{sub 2}-CH{sub 2}NNN-Ad-κ{sup 2}N{sup 1,3})]. Similarly, a single equivalent of CS{sub 2} reacts with 1 to form the mixed tethered alkyl dithiocarboxylate complex [(η{sup 5}-C{sub 5}Me{sub 4}SiMe{sub 2}CH{sub 2}-κC)U(η{sup 5}-C{sub 5}Me{sub 4}SiMe{sub 2}- CH{sub 2}C(S){sub 2}-κ{sup 2}S,S{sup '})], a reaction that constitutes the first example of CS{sub 2} insertion into a U{sup 4+}-C bond. Complex 1 reacts with one equivalent of pyridine N-oxide by C-H bond activation of the pyridine ring to form a mixed tethered alkyl cyclometalated pyridine N-oxide complex [(η{sup 5}-C{sub 5}Me{sub 4}SiMe{sub 2}CH{sub 2}-κC)(η{sup 5}-C{sub 5}Me{sub 4}SiMe{sub 3})U(C{sub 6}H{sub 4}NO-κ{sup 2} C,O)]. The remaining (η{sup 5}-C{sub 5}Me{sub 4}SiMe{sub 2}CH{sub 2}-κC){sup 2-} ligand in each of these mixed tethered species show reactivity towards CO and tethered enolate ligands form by insertion. Subsequent rearrangement have been identified in [(η{sup 5}-C{sub 5}Me{sub 4}SiMe{sub 3})U(C{sub 5}H{sub 4}NO-κ{sup 2}C,O)(η{sup 5}-C{sub 5}Me{sub 4}SiMe{sub 2}C(=CH{sub 2})O- κO)] and [(η{sup 5}-C{sub 5}Me{sub 4}SiMe{sub 2}CH{sub 2}NNN-Ad-κ{sup 2}N{sup 1,3})U(η{sup 5}-C{sub 5}Me{sub 4}SiMe{sub 2}C(=CH{sub 2})O-κO)]. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  1. Organic synthesis via group 4 metallocene complexes

    Energy Technology Data Exchange (ETDEWEB)

    Grossman, R.B.

    1992-01-01

    The syntheses of the known chiral zirconocene compound ethylene-1,2-bis([eta][sup 5]-4,5,6,7-tetrahydro-1-indenyl)zirconium dichloride and the corresponding hafnium compound have been improved, and a new, reproducible method for the resolution of the zirconium compound has been developed. Syntheses of the corresponding methylzirconium triflate and dimeric zirconium dihydride complexes has also been developed. The triflate represents a chiral, enantiopure analog of methylzirconocene chloride, a useful reagent for the synthesis of organic compounds. A simple procedure for the synthesis of enantiomerically pure allylic N-arylamine via the zirconium-mediated coupling of an achiral N-arylamine and an unactivated alkyne is presented. The allylic amines are prepared in moderate to good yields with very high ee's (90-99%) in most cases. The key steps of the reaction sequence involve the highly diastereoselective formation of an complex via a C-H activation reaction followed by a stereospecific insertion of an alkyne into a carbon-zirconium bond to give a 2-zircona-3-pyrroline. The mechanisms of these reactions have been investigated. The data indicate the the C-H activation reaction is only slightly diastereoselective. An unusual structure for the benzaldimine complex has been proposed, and mechanisms that explain the different diastereoselectivities that are observed upon coupling of nitriles, alkynes, and olefins to alkaldimine and benzaldimine complexes are suggested. A practical reagent has been discovered which effects the reductive cyclization of enynes to bicyclic titanacyclopentenes. This reagent, Cp[sub 2] TiCl[sub 2]/2 n-BuLi, is tolerant of ester and either functionality in cyclic cyclopentenones by carbonylation in chloroform or into iminocyclopentenes by treatment with isocyanides in moderate to good isolated yields. In the latter system, the intermediate iminoacylthitanium compounds are sometimes observable by [sup 1]H NMR.

  2. Organo-Lewis acid as cocatalyst for cationic homogeneous metallocene Ziegler-Natta olefin polymerizations

    Energy Technology Data Exchange (ETDEWEB)

    Marks, T.J.; Chen, Y.X.

    2000-07-11

    The synthesis of the organo-Lewis acid perfluorobiphenylborane (PBB) and the activation of metallocenes are disclosed for the formation of a variety of highly active homogeneous Ziegler-Natta metallocene olefin polymerization, copolymerization and ring-opening polymerization catalysts is described.

  3. Group 4 metallocene complexes with pendant nitrile groups

    Czech Academy of Sciences Publication Activity Database

    Pinkas, Jiří; Gyepes, R.; Kubišta, Jiří; Horáček, Michal; Lamač, Martin

    2011-01-01

    Roč. 696, 11-12 (2011), s. 2364-2372 ISSN 0022-328X R&D Projects: GA ČR GPP207/10/P200; GA MŠk(CZ) LC06070 Institutional research plan: CEZ:AV0Z40400503 Keywords : metallocene * group 4 elements * nitrile Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.384, year: 2011

  4. Carbon monoxide and isocyanide complexes of trivalent uranium metallocenes

    International Nuclear Information System (INIS)

    Mar Conejo, M. del; Parry, J.S.; Carmona, E.; Schultz, M.; Brennann, J.G.; Beshouri, S.M.; Andersen, R.A.; Rogers, R.D.; Coles, S.; Hursthouse, M.

    1999-01-01

    The [Cp' 3 U] metallocenes contain substituted cyclopentadienyl ligands and U III with f 3 electron configuration. They are good π donors and bind π-accepting ligands (L) such as carbon monoxide and isocyanides to form the corresponding adducts [Cp' 3 U(L)]. The π-donating capability of the [Cp' 3 U] fragments appears to be readily modulated by the substituents on the cyclopentadienyl ligand. (orig.)

  5. Synthesis of ferrocenestrone: the first metallocene based steroid analogue

    Czech Academy of Sciences Publication Activity Database

    Hessler, F.; Císařová, I.; Sedlák, David; Bartůněk, Petr; Kotora, Martin

    2012-01-01

    Roč. 18, č. 18 (2012), s. 5515-5518 ISSN 0947-6539 R&D Projects: GA MŠk(CZ) 1M0508; GA ČR GA204/09/1905; GA MŠk(CZ) LC06077 Institutional support: RVO:68378050 ; RVO:61388963 Keywords : asymmetric synthesis * ferrocenestrones * metallocene s * steroids * synthesis design Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 5.831, year: 2012

  6. Synthesis of ferrocenestrone: the first metallocene based steroid analogue.

    Science.gov (United States)

    Hessler, Filip; Císařová, Ivana; Sedlák, David; Bartůněk, Petr; Kotora, Martin

    2012-04-27

    Ferrocenestrone, the first steroid derivative containing a metallocene moiety, was stereoselectively prepared. The key steps included the enantioselective functionalization of ferrocene, elongation of the side chain, intramolecular enyne metathesis, Diels-Alder reaction, heterogeneous hydrogenation of the sterically hindered double bond, and finally inversion of the configuration at C13. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Strongly correlated electron physics in nanotube-encapsulated metallocene chains

    Science.gov (United States)

    García-Suárez, V. M.; Ferrer, J.; Lambert, C. J.

    2006-11-01

    The structural, electronic, and transport properties of metallocene molecules (MCp2) and isolated or nanotube-encapsulated metallocene chains are studied by using a combination of density functional theory and nonequilibrium Green’s functions. The analysis first discusses the whole series of isolated (MCp2) molecules, where M=V , Cr, Mn, Fe, Co, Ni, Ru, and Os. The series presents a rich range of electronic and magnetic behaviors due to the interplay between the crystal field interaction and Hund’s rules, as the occupation of the d shell increases. The article then shows how many of these interesting properties can also be seen when (MCp2) molecules are linked together to form periodic chains. Interestingly, a large portion of these chains display metallic, and eventually magnetic, behavior. These properties may render these systems as useful tools for spintronics applications but this is hindered by the lack of mechanical stability of the chains. It is finally argued that encapsulation of the chains inside carbon nanotubes, that is exothermic for radii larger than 4.5Å , provides the missing mechanical stability and electrical isolation. The structural stability, charge transfer, magnetic, and electronic behavior of the ensuing chains, as well as the modification of the electrostatic potential in the nanotube wall produced by the metallocenes are thoroughly discussed. We argue that the full devices can be characterized by two doped, strongly correlated Hubbard models whose mutual hybridization is almost negligible. The charge transferred from the chains produces a strong modification of the electrostatic potential in the nanotube walls, which is amplified in case of semiconducting and endothermic nanotubes. The transport properties of isolated metallocenes between semi-infinite nanotubes are also analyzed and shown to lead to important changes in the transmission coefficients of clean nanotubes for high energies.

  8. Tuning the Electrical Conductivity of Nanotube-Encapsulated Metallocene Wires

    Science.gov (United States)

    García-Suárez, Víctor M.; Ferrer, Jaime; Lambert, Colin J.

    2006-03-01

    We analyze a new family of carbon nanotube-based molecular wires, formed by encapsulating metallocene molecules inside the nanotubes. Our simulations, which are based on a combination of nonequilibrium Green function techniques and density functional theory, indicate that these wires can be engineered to exhibit desirable magnetotransport effects for use in spintronics devices. The proposed structures should also be resilient to room-temperature fluctuations, and are expected to have a high yield.

  9. Modeling intraparticle transports during propylene polymerizations using supported metallocene and dual function metallocene as catalysts: Single particle model

    Directory of Open Access Journals (Sweden)

    Li Hua-Rong

    2014-01-01

    Full Text Available Two improved multigrain models (MGMs for preparing homopolypropylene and long chain branched polypropylene via propylene polymerization using silica-supported metallocene or dual function metallocene as catalysts are presented in this paper. The presented models are used to predict the intraparticle flow fields involved in the polymerizations. The simulation results show that the flow field distributions involve dare basically identical. The results also show that both the two polymerization processes have an initiation stage and the controlling step for them is reaction-diffusion-reaction with the polymerization proceeding. Furthermore, the simulation results show that the intra particle mass transfer resistance has significant effect on the polymerization but the heat transfer resistance can be ignored.

  10. Palladium-catalyzed intramolecular asymmetric C-H functionalization/cyclization reaction of metallocenes: an efficient approach toward the synthesis of planar chiral metallocene compounds.

    Science.gov (United States)

    Deng, Ruixian; Huang, Yunze; Ma, Xinna; Li, Gencheng; Zhu, Rui; Wang, Bin; Kang, Yan-Biao; Gu, Zhenhua

    2014-03-26

    A palladium-catalyzed asymmetric synthesis of planar chiral metallocene compounds is reported. The reaction stereoselectively functionalized one of the ortho C-H bonds of Cp rings by intramolecular cyclization to form indenone derivatives in high yields with excellent enantioselectivity. The mild set of reaction conditions allowed a wide variety of chiral metallocene compounds to be synthesized with broad functional group tolerance. The influences of preinstalled chiralities on the other Cp-ring were also investigated.

  11. Biological Interaction of Molybdenocene Dichloride with Bovine Serum Albumin Using Fluorescence Spectroscopy

    Science.gov (United States)

    Domínguez, Moralba; Cortes-Figueroa, Jose´ E.; Meléndez, Enrique

    2018-01-01

    Bioinorganic topics are ubiquitous in the inorganic chemistry curriculum; however, experiments to enhance understanding of related topics are scarce. In this proposed laboratory, upper undergraduate students assess the biological interaction of molybdenocene dichloride (Cp2MoCl2) with bovine serum albumin (BSA) by fluorescence spectroscopy.…

  12. The absorption, tissue distribution and excretion of di-n-octyltin dichloride in rats

    NARCIS (Netherlands)

    Penninks, A.H.; Hilgers, L.; Seinen, W.

    In this study the absorption, tissue distribution and excretion of 14C-labeled di-n-octyltin dichloride ([14C]DOTC) in rats were investigated after oral and intravenous (i.v.) administration. Although after i.v. administration with 1.2 mg [14C]DOTC/kg body weight the tissue radioactivity was about

  13. Photobleaching of Sn(IV) chlorine e6 dichloride trisodium salt in ...

    African Journals Online (AJOL)

    The photobleaching of Sn(IV) chlorine e6 dichloride trisodiuim salt in variety of solvents was investigated. The absorption of photosensitizer in polar solvent was much higher than in non-polar solvent. The results prove that this photosensitizer was high water soluble. The photosensitizer absorption decreased at all bands ...

  14. Reactions of 3d-series metallocenes with organic cadmium compounds

    International Nuclear Information System (INIS)

    Razuvaev, G.A.; Mar'in, V.P.; Vyshinskaya, L.I.; Grinval'd, I.I.; Spiridonova, N.N.

    1987-01-01

    Interaction of organic cadmium compounds and 3d-series metallocenes, Cp 2 M (M=V, Cr, Mn, Ni, Co) has been studied. It is shown that direction of these reactions is determined by metallocene nature. Reactions of oxidizing addition leading to σ-complexes formation are characteristic for vanadium and chromium metallocenes. When reacting cobaltocene with R 2 Cd, R group introduction to cyclopentadienyl ring and elimination of cobalt diene complexes take place. Manganocene and nickelocene interaction goes through the stage of complex formation with transition metal - cadmium bond

  15. Preparation, characterization, and activity of α-Ti(HPO4)2 supported metallocene catalysts

    Science.gov (United States)

    Shi, Yasai; Yuan, Yuan; Xu, Qinghong; Yi, Jianjun

    2016-10-01

    A series of heterogeneous catalysts by loading metallocenes on surface of α-Ti(HPO4)2, a kind of solid acid, has been synthesized. Polymerization of alkenes, including ethylene and propylene, based on participation of the heterogeneous catalysts were studied and the results were compared to metallocenes supported on silica gel, α-Zr(HPO4)2 and clay. Higher catalytic activity, larger polymer molecular weight and narrow distribution of polymer molecular weight were obtained. Acidic strength of the support and its influence to metallocenes were studied to discover intrinsic factors in the polymerizations.

  16. Simple correlation between the main luminescence parameters of the metallocene complex in the liquid phase

    International Nuclear Information System (INIS)

    Lukova, G.V.; Vasil'ev, V.P.; Smirnov, V.A.

    2007-01-01

    The lifetimes (τ) of excited states of the metallocene rac-C 6 H 10 (IndH 4 ) 2 ZrCl 2 (Ind = indenyl) in solutions have been studied. This metallocene features intensive luminescence in the liquid phase at room temperature. The main luminescence characteristics (Φ L and τ) of the complex in solutions are shown to strongly depend on the solvent nature. Long lifetimes and high luminescence yields are observed in solutions with strong solvating ability to metallocene complexes. The solvent defines the rate of radiationless deactivation, that becomes apparent in a linear correlation between Φ L and τ parameters [ru

  17. Hot atom reactions in mixed crystals of iron group metallocenes

    International Nuclear Information System (INIS)

    Yassine, T.; Blackburn, R.

    1989-01-01

    Neutron irradiations of mixed crystals of pairs of ferrocene, ruthenocene, and osmocene were carried out and a theoretical model is proposed to explain the behaviour of recoil metal species in the irradiated matrices. The proposed model is based on ion-molecule reactions which are controlled by several factors, which include the ionisation potentials of the reactants and the internal energies of both reactants and products. Most of the observed retention data on the mixed metallocene systems appear to be consistent with the proposed explanation. (author)

  18. Planar pentacoordinate carbon atoms embedded in a metallocene framework.

    Science.gov (United States)

    Cui, Zhong-Hua; Vassilev-Galindo, Valentin; Luis Cabellos, José; Osorio, Edison; Orozco, Mesías; Pan, Sudip; Ding, Yi-Hong; Merino, Gabriel

    2016-12-20

    Viable planar pentacoordinate carbon (ppC) systems with a ppC bonded to a transition metal and embedded in a metallocene framework are reported. Our detailed global minima search shows that CAl 4 MX 2 (M = Zr and Hf; X = F-I and C 5 H 5 ) clusters with ppCs are appropriate candidates for experimental realization in the gas phase. The fulfillment of the 18 electron rule and electron delocalization is found to be crucial for the stabilization of these ppC arrangements.

  19. Hot atom reactions in mixed crystals of iron group metallocenes

    International Nuclear Information System (INIS)

    Yassine, T.; Blackburn, R.

    1990-01-01

    Neutron irradiations of mixed crystals of pairs of ferrocene, ruthenocene, and osmoscene were carried out and a theoretical model is proposed to explain the behaviour of recoil metal species in the irradiated matrices. The proposed model is based on ion-molecule reactions which are controlled by several factors, which include the ionisation potentials of the reactants and the internal energies of both reactants and products. Most of the observed retention data on the mixed metallocene systems appear to be consistent with the proposed explanation. (author). 9 refs., 5 figs., 2 tabs

  20. Dipole moment of metallocene precatalyst in ground and excited states

    International Nuclear Information System (INIS)

    Lukova, G.V.; Vasil'ev, V.P.; Smirnov, V.A.; Milov, A.A.

    2008-01-01

    Electric dipole momenta of high-emitting metallocene precatalyst, i.e. π-complex of Zr IV (ras-C 6 H 10 (IndH 4 ) 2 ZrCl 2 ) in basic and triplet states in series of diluents have been estimated by the method of spectral shifts and quantum-chemical calculations using the DFT method. The absorption spectra characteristic of charge transfer from the ligand to metal and of zirconocene luminescence depend on the aprotic diluent nature. It is shown that transition from S 0 state to emitting T 1 state entails essential increase in the electric dipole momentum [ru

  1. Constitutive modeling of the viscoelastic and viscoplastic responses of metallocene catalyzed polypropylene

    DEFF Research Database (Denmark)

    Drozdov, Aleksey; Christiansen, Jesper de Claville; Sanporean, Catalina-Gabriela

    2012-01-01

    Purpose – The purpose of this paper is to perform experimental investigation and constitutive modeling of the viscoelastic and viscoplastic behavior of metallocene catalyzed polypropylene (mPP) with application to lifetime assessment under conditions of creep rupture. Design/methodology/approach ......Purpose – The purpose of this paper is to perform experimental investigation and constitutive modeling of the viscoelastic and viscoplastic behavior of metallocene catalyzed polypropylene (mPP) with application to lifetime assessment under conditions of creep rupture. Design...... an arbitrary three-dimensional deformation with small strains, and its parameters are found fitting the observations. Findings – Crystalline structure and molecular architecture of polypropylene strongly affect its time and rate-dependent behavior. In particular, time-to-failure of metallocene catalyzed...... in long-term creep tests. Keywords Metallocene catalyzed polypropylene, Viscoelasticity, Viscoplasticity, Creep rupture, Constitutive modeling, Elastoplastic analysis, Viscosity, Creep, Physical properties of materials Paper type Research paper...

  2. Photophysical properties and coordination interaction of d0 metallocenes with unsaturated hydrocarbons

    International Nuclear Information System (INIS)

    Lukova, G.V.; Smirnov, V.A.; Starodubova, S.E.

    2005-01-01

    On the basis of photophysical experiment data one showed for the first time the triplet nature of long-lived excited states of organometallic compounds formed due to transfer of charge from ligand to metal in metallocene complexes of titanium(IV), zirconium(IV) and hafnium(IV). One revealed a strong specific interaction of Cp 2 MCl 2 (M = Zr 4+ , Hf 4+ ) metallocenes with polymerization catalytic system substrates - ethylene and diene series unsaturated hydrocarbons [ru

  3. The enthalpies of formation of neutral and charged components of saturated vapor over europium dichloride

    International Nuclear Information System (INIS)

    Pogrebnoj, A.M.; Kudin, L.S.

    2003-01-01

    Composition of saturated vapor over europium dichloride was studied by the method of high-temperature mass spectrometry in the temperature range of 1154 - 1267 K. For neutral components of the vapor, represented by monomer and dimer molecules, partial pressures were determined. Enthalpies of sublimation of europium dichloride Δ s H 0 (298 K) as monomers (338 ± 9) and dimers (407 ± 20 kJ/mol) were calculated. Equilibrium constants of ion-molecular and ion-ionic reactions were measured, their enthalpies being ascertained. Enthalpies of formation of molecules and ions Δ f H 0 (298 K) were calculated: -486 ± 11 (EuCl 2 ), -1242 ± 22 (Eu 2 Cl 4 ), 1 ± 12 (Eu 2 Cl 2 + ), -347 ± 20 (Eu 2 Cl 3 + ), -1111 ± 42 (Eu 3 Cl 5 + ), -975 ± 20 (EuCl 3 - ), -1309 ± 17(EuCl 4 - ), -1734 ± 20 (Eu 2 Cl 5 - ) kJ/mol [ru

  4. Characteristics of the blends of metallocene catalyzed polymer and polyethylene

    Energy Technology Data Exchange (ETDEWEB)

    Kim, K.S. [LG Chemical Ltd. (Korea); Hong, S.K. [Chungnam National University, Taejon (Korea)

    1999-07-01

    The metallocene PE(m-PE)/HDPE and m-PE/LDPE blend systems show typical miscible behavior in the solid state. The yield strength and elongation decreased with the addition of m-PE, while the tensile strength at break, contrary to the yield strength, increased with the content of m-PE. The melting and crystallization behavior of the blend were dominated by HDPE. The melting temperature and the heat of fusion were linearly decreased with the m-PE content. This result shows that the metallocene PEs have a good low temperature heat-seability. The flow rate of blends under large load (21.6 kg) increased with the addition of m-PE, but the flow rate under small load (2.16 kg and 5 kg) decreased with the m-PE content. The melt flow rate ratio decreased with the m-PE content while the torque value of blend increased. These results indicate that the processibility of m-PE/HDPE or LDPE decreases with m-PE content. 18 refs., 12 figs.

  5. Linear uranium metallocenes with polydentate aromatic nitrogen ligands

    International Nuclear Information System (INIS)

    Berthet, Jean-Claude; Thuery, Pierre; Ephritikhine, Michel; Maynadie, Jerome

    2010-01-01

    Treatment of [Cp 2 *U(NCMe) 5 ]X 2 [Cp* = C 5 Me 5 , X = BPh 4 (1) or I (1')] or Cp 2 *UI 2 in acetonitrile with the polydentate aromatic nitrogen bases phen, terpy and R 4 btbp led to the formation of the linear uranium metallocenes [Cp 2 *U(NCMe) 3 (phen)]X 2 [X = BPh 4 (2), I (2')], [Cp 2 *U(NCMe) 2 (terpy)][BPh 4 ] 2 (4), [Cp 2 *U(NCMe)(Me 4 btbp)][BPh 4 ] 2 (5) and [Cp 2 *U(NCMe)(CyMe 4 btbp)][X] 2 , [X = BPh 4 (6), I (6')], [phen 1, 10-phenanthroline, terpy = 2, 2':6, 2''-terpyridine, Me 4 btbp 6, 6'-bis-(3, 3, 6, 6-tetramethyl-1, 2, 4-triazin-3-yl)-2, 2'-bipyridine, CyMe 4 btbp = 6, 6'-bis-(3, 3, 6, 6-tetramethyl-cyclohexane-1, 2, 4-triazin-3-yl)-2, 2'-bipyridine]. The bent metallocene [Cp 2 *U(phen) 2 ][BPh 4 ] 2 (3) was isolated from the reaction of 1 and two molar equivalents of phen in THF. The X-ray crystal structures of 2.2MeCN, 3.2THF, 4 and 6'center dot 2MeCN were determined. (authors)

  6. Scoping economics for the commercial manufacture of metallocene catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Brockmeier, N.F.

    1994-05-26

    This study assumes that commercial-scale production of propylene-based isotactic polymers with metallocene catalyst systems will become a reality. The challenge that must be overcome for commercial success with these propylene polymers is to discover a metallocene system recipe that will give sufficient catalyst activity along with the requisite stereo-selectivity at reasonable cost. Anticipating such a discovery, it is assumed here that the economics are well-represented by a catalyst system that consists in part of a silylene-bridged cyclopentadienyl zirconocene made in a batchwise process having an annual capacity of 15,000 pounds. Activation will be achieved with a cocatalyst such as methylaluminoxane (MAO), coated in conjunction with the catalyst on a support such as silica. The MAO at an estimated $100/lb contributes $1800/lb cost to the finished catalyst with an assumed recipe of 18:1 mass ratio of MAO to zirconocene. Based on a 20% return on investment, the selling price for the supported zirconocene system is estimated to be $2915/lb. The required capital investment to make 735,000 lb/yr of the total supported system is 9 million dollars. These estimates have {plus_minus}50% range of uncertainty. Payback period for this plant in a sold-out condition is three years. The catalyst system cost in ethylene-propylene copolymer is 3.9 cents per pound with a productivity of 75,000 lb polymer/lb of zirconocene. An Appendix includes some economic details.

  7. Competitive adsorption between benzene and ethylene dichloride on activated carbon: The importance of concentration

    Science.gov (United States)

    Miao, T.; Tang, H. M.; Cheng, Z. X.

    2018-03-01

    In this work we studied breakthroughs of binary mixtures of benzene and ethylene dichloride on fixed activated carbons bed. The results show a series of assault concentrations on activated carbon bed influences the nature of the adsorption competition mechanism. Assault concentration were used to determine how competition of compound distribution. The results are discussed in terms of competing energetic and the underlying molecular mechanisms. The ratio of assault concentrations is main reason for determining selectivity.

  8. Hyaluronidase: its effects on HI-6 dichloride and dimethanesulphonate pharmacokinetic profile in pigs.

    Science.gov (United States)

    Karasova, Jana Zdarova; Pavlik, Michal; Chladek, Jaroslav; Jun, Daniel; Kuca, Kamil

    2013-07-04

    Pigs were administered intramuscularly molar equivalents of HI-6 salts (HI-6 dichloride 10.71 mg/kg and HI-6 DMS 13.59 mg/kg) either with or without hyaluronidase (60 U/kg). Hyaluronidase is supposed to increase tissue permeability and diminishes discomfort caused by the intramuscular injection. Doses of HI-6 salts corresponded with standard HI-6 dichloride dose in one autoinjector (500 mg) and were recalculated for 1 kg of body weight. According to the results, both HI-6 salts applied in combination with hyaluronidase had increased tissue absorption and improved pharmacokinetic profile. The Cmax was significantly higher in case of HI-6 DMS plus hyaluronidase (29.6 ± 2.98 μg/ml) administration increase compared to HI-6 DMS (23.8 ± 3.04 μg/ml) and HI-6 dichloride (19.0 ± 0.93 μg/ml); both without hyaluronidase. Bioavailability calculated as AUCtotal (HI-6 DMS with hyaluronidase, 4,119 ± 647 min μg/ml) was also significantly higher compared to HI-6 DMS (2,259 ± 329 min μg/ml) and HI-6 dichloride (1,969 ± 254 min μg/ml); both without hyaluronidase. The results suggest that administration of HI-6 salt with higher solubility is the first step in the improvement of application strategy, but use some substances with spreading effect (hyaluronidase) may also leads to better absorption and better bioavailability. Improved bioavailability could to go hand in hand with increased effectiveness of therapy without the need of multiple autoinjector applications. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  9. A spiral-like chain from a hydrogen-bonded cyclic dichloride ...

    Indian Academy of Sciences (India)

    The O-H ⋯ Cl and O-H ⋯ O interactions between the chloride anions and water molecules lead to the formation of a five-membered {O3Cl2} cyclic dichloride containing a water dimer. The five-membered rings are linked into a chain with the aid of a O-H ⋯ Cl interaction. The organic cations are organised in zigzag fashion ...

  10. Chain structure, aggregation state structure, and tensile behavior of segmented ethylene-propylene copolymers produced by an oscillating unbridged metallocene catalyst.

    Science.gov (United States)

    Tong, Zai-Zai; Huang, Yao; Xu, Jun-Ting; Fu, Zhi-Sheng; Fan, Zhi-Qiang

    2015-05-14

    Segmented ethylene-propylene copolymers (SEPs) with different propylene contents were prepared by an unbridged metallocene bis(2,4,6-trimethylindenyl)zirconium dichloride [(2,4,6-Me3Ind)2ZrCl2] catalyst. Due to oscillation of the unbridged ligands in the catalyst, the SEPs are composed of segments with low propylene contents, alternated by the segments with high propylene contents. Such a chain structure was verified by (13)C NMR and successive self-nucleation and annealing (SSA). As the propylene/ethylene feed ratio during copolymerization increases, the comonomer contents in both segments are increased, leading to noncrystallizability of the high propylene segments and smaller crystallinity of the low propylene segments. Consequently, SEPs may be used as thermoplastic elastomers (TPEs). The aggregation state structures at nano- and micro-scales were characterized with small angle X-ray scattering, transmission electron microscopy and polarized optical microscopy, and compared with those of ethylene-octene multiblocky copolymers (OBCs) with similar crystallinity. It is found that SEPs form thinner lamellar crystals with a lower melting temperature due to shorter length and higher comonomer content of the low propylene segments. Moreover, the short length of the high propylene segments in SEPs results in an evidently thinner amorphous layer among the lamellar crystals, thus lots of amorphous phases are excluded out of the interlamellae. Accordingly, ill-developed spherulites or even bundle crystals are formed in SEPs, as compared with the well-developed spherulites in OBCs. SEPs exhibit the tensile property of typical TPEs with diffused yielding and large strain at break.

  11. Depuration Technique of Xenobiotics with Reference to Accumulation and Elimination of Paraquat Dichloride in Clarias Gariepinus

    Directory of Open Access Journals (Sweden)

    Thomas Ikpesu

    2013-09-01

    Full Text Available Background: Paraquat dichloride is a highly toxic herbicide which is still used in many developing countries. African cat fish (Clarias gariepinus is a commercially important species in many countries and was selected assess accumulation and elimination of paraquat dichloride in its tissues.Methods: Groups of ten fish with equal lengths and weights were exposed to varying concentrations of Paraquat dichloride for 28 days. After the exposure, the fish were transferred to uncontaminated water. Two fish were sampled for pesticide residue at the end of exposure period (28days and 1, 7 and 14 days post exposure. Results: In pesticide treated fish, the accumulation of paraquat increased with increases in the concentration of the toxicant and varied significantly between the treatments (p < 0.05. The herbicide depurated gradually with cessation of exposure and no pesticide was observed after 14 days. Conclusion: Xenobiotics could be eliminated from aquatic organisms especially fishes and could be put into practice in areas at risk of pollutants. This novel approach can reduce the risks of biomagnification of poisons in sea food.

  12. Comparison of Ethylene/1-Hexene Copolymers Microstructures Synthesized by Homogeneous and Heterogeneous Metallocene Catalysts

    Directory of Open Access Journals (Sweden)

    Saeid Ahmadjo

    2013-05-01

    Full Text Available The substituted (bis-2-PhIndZrCl2 and non-substituted (bis-IndZrCl2 indenylbased metallocene catalysts were synthesized and used in homogenous and heterogeneous forms for copolymerization of ethylene and 1-hexene. The MCM-41 nano silica was used as support in heterogenization of the catalysts. The substituted (bis-2-PhIndZrCl2 metallocene catalyst in homogenous and heterogeneous forms showed lower activities in comparison to non-substituted (bis-IndZrCl2 metallocene catalyst. The microstructures of the obtained copolymers were investigated by techniques such as DSC, CNMR and TRRF. The kinetic study showed that the decay index (DI was decreased for both homogeneous catalysts due to unstable kinetic behaviors. However, the decay index contents approached one, using heterogeneous forms of catalyst which was an indication of stable kinetic behaviors. The kinetic results also displayed negative effect on the catalysts activities both in the homogeneous and heterogeneous forms by addition of comonomer on the polymerization. The triad distributions of obtained polymer by NMR technique exhibited the higher ratio of EEH, EHE, EEE triads than the other triads. The comonomer incorporationacceptability of substituted metallocene catalyst (bis-2-PhIndZrCl2 was higher than non-substituted catalyst (bis-IndZrCl2 as its comonomer acceptability increased from 1.3% to 5.4% by substitution mechanism. Microstructures of copolymers obtained by supported metallocene catalyst showed more non-uniform comonomer distribution in comparison with unsupported catalyst. The lamella thickness distributions for polymer obtained by supported substituted metallocene catalyst (bis-2-PhIndZrCl2 were in the ranges (3-8 . However, for supported metallocene non-substituted catalysts (bis-IndZrCl2 the lamella thickness were in the ranges (3-16 .

  13. Branching structure and strain hardening of branched metallocene polyethylenes

    International Nuclear Information System (INIS)

    Torres, Enrique; Li, Si-Wan; Costeux, Stéphane; Dealy, John M.

    2015-01-01

    There have been a number of studies of a series of branched metallocene polyethylenes (BMPs) made in a solution, continuous stirred tank reactor (CSTR) polymerization. The materials studied vary in branching level in a systematic way, and the most highly branched members of the series exhibit mild strain hardening. An outstanding question is which types of branched molecules are responsible for strain hardening in extension. This question is explored here by use of polymerization and rheological models along with new data on the extensional flow behavior of the most highly branched members of the set. After reviewing all that is known about the effects of various branching structures in homogeneous polymers and comparing this with the structures predicted to be present in BMPs, it is concluded that in spite of their very low concentration, treelike molecules with branch-on-branch structure provide a large number of deeply buried inner segments that are essential for strain hardening in these polymers

  14. Metallocene Molecular Clusters Studied with Scanning Tunneling Microscopy and Spectroscopy

    Science.gov (United States)

    Kwon, Jeonghoon; Ham, Ungdon; Lee, Minjun; Lim, Seong Joon; Kuk, Young

    2014-03-01

    Atomic spins and molecular magnets have been actively reported using Scanning Tunneling Microscope(STM) in recent studies. One can even assemble an artificial magnet by STM manipulation. Manganocene((C5H5)2 Mn), a sandwich complex of metallocene, is composed of one manganese atom and two cyclopentadianyl ligands. This molecule is known to reveal not only high spin number S = 5/2 at room temperature but also two structural states: monomer and molecular chain. In this presentation, we report STM images and spectroscopic results of these monomers and dimers. We try to map the molecular electronic state and the spin texture. The molecule is adsorbed on an insulating layer to decouple the spin state from the metallic substrate. We will present that manganocene can become a basic element of a spin chain.

  15. Metallocene-based nanocomposites as cathode materials in lithium batteries

    Energy Technology Data Exchange (ETDEWEB)

    Prakash, Raju; Wall, Clemens; Fichtner, Maximilian [Karlsruhe Institute of Technology (KIT), Institute of Nanotechnology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany)

    2010-07-01

    Lithium-ion batteries have been the most utilized batteries in the portable electronic market since many years. But their performance still lies behind the demands of the consumer. New electrode materials with high specific capacities are necessary to meet these demands. Metal fluorides have high theoretical specific capacity based on a novel conversion mechanism, making them promising cathode materials for high performance lithium-ion batteries. However, the metal fluoride cathodes are still hampered by loss of capacity and cyclic instability. Hence, a new approach such as encapsulation of active materials in nanotubes or carbon-coating, etc. is needed in order to improve their performance. Herein, we present a simple method based on the thermal decomposition of a metallocene/LiF mixture to produce inexpensive cathode materials which exhibit a good cyclic stability and reversibility. The detailed structural investigations of the nanocomposites as well as their electrochemical performances are presented.

  16. Steric and electronic interactions between cofacial metallocene rings

    Energy Technology Data Exchange (ETDEWEB)

    Arnold, R.; Foxman, B.M.; Rosenblum, M.; Euler, W.B.

    1988-06-01

    As part of a study of interactions between metallocenes, held so that two cyclopentadienyl rings are constrained to be proximate and facing one another, 1,8-diruthenocenylnaphthalene has been prepared and its crystal structure has been determined. This structure is shown to be close to that of 1,8-diferrocenylnaphthalene reported earlier, especially in respect to the dihedral angle between the substituted cyclopentadienyl and naphthalene ring planes and the splay angle between the two substituted cyclopentadienyl rings. Both of these distortions are significantly diminished in the monocation derived from 1a, suggesting that there is a significant decrease in electron density on the cyclopentadienyl rings on oxidation of ferrocene to a ferricenium cation, consistent with theoretical analyses.

  17. Branching structure and strain hardening of branched metallocene polyethylenes

    Energy Technology Data Exchange (ETDEWEB)

    Torres, Enrique; Li, Si-Wan; Costeux, Stéphane; Dealy, John M., E-mail: john.dealy@mcgill.ca [Department of Chemical Engineering, McGill University, Montreal, Quebec H3A 0C4 (Canada)

    2015-09-15

    There have been a number of studies of a series of branched metallocene polyethylenes (BMPs) made in a solution, continuous stirred tank reactor (CSTR) polymerization. The materials studied vary in branching level in a systematic way, and the most highly branched members of the series exhibit mild strain hardening. An outstanding question is which types of branched molecules are responsible for strain hardening in extension. This question is explored here by use of polymerization and rheological models along with new data on the extensional flow behavior of the most highly branched members of the set. After reviewing all that is known about the effects of various branching structures in homogeneous polymers and comparing this with the structures predicted to be present in BMPs, it is concluded that in spite of their very low concentration, treelike molecules with branch-on-branch structure provide a large number of deeply buried inner segments that are essential for strain hardening in these polymers.

  18. Structural complexity in the rare earth metallocene hydride complexes, [(C₅Me₅)₂LnH]₂.

    Science.gov (United States)

    Liu, Shan-Shan; Gao, Song; Ziller, Joseph W; Evans, William J

    2014-11-07

    X-ray crystallographic data obtained on the metallocene hydrides, [(C5Me5)2LnH]2 (Ln = Gd, Tb, and Dy), of interest for their magnetic properties, have revealed unexpected structural variability in a closely related series of rare earth complexes that can complicate magnetic analysis. Crystals of the two larger metals, Gd and Tb, were structurally straightforward and isomorphous with crystals of [(C5Me5)2SmH]2. However, only for Tb were the locations of the hydride ligands in this structural type identified for the first time and found to be consistent with a (C5Me5)2Ln(μ-H)2Ln(C5Me5)2 structure. In contrast, for Ln = Dy, the [(C5Me5)2H](3-) ligand set does not appear to have one optimum crystal structure. Two different types of crystals and one other solid form of [(C5Me5)2DyH]2 were repeatedly isolated upon crystallization and demonstrated that the structure of any particular crystalline sample selected for magnetic analysis could be variable. Asymmetric structures with a single hydride bridge, (C5Me5)2Dy(μ-H)DyH(C5Me5)2, were identifiable for the two crystalline forms. This demonstrated uncertainty in structure and highlights the importance of having a coordination environment with one preferred form for magnetically interesting complexes.

  19. Porous Organic Polymers-Supported Metallocene Catalysts for Ethylene/1-Hexene Copolymerization

    Directory of Open Access Journals (Sweden)

    Xiong Wang

    2018-04-01

    Full Text Available Porous organic polymers (POPs have received much attention in adsorption, separation, and catalysis. In this paper, porous organic polymers with different pore structure were used as metallocene catalyst supports, and ethylene/1-hexene copolymerizations were conducted using the POPs-supported metallocene catalyst. The pore structure of the prepared POPs and the supported metallocene catalyst were characterized by nitrogen sorption porosimetry and non-local density functional theory simulation, and the molecular chain structure of the produced ethylene/1-hexene copolymers were investigated through gel permeation chromatography (GPC, IR analysis, differential scanning calorimetry (DSC, and temperature rising elution fractionation (TREF. The results show that the loading amount of active sites varied with different pore structures of the POP supports, and the active species scattered in different pore sizes had a moderate impact on the molecular chain growth and the molecular weight distribution. The IR, DSC, and TREF analysis revealedthat different branching degree, double bond content, and chemical composition distributions were detected from the molecular chain structure of the ethylene/α-olefin copolymers from different POPs and silica-supported metallocene catalysts, despite their similar IR, DSC, and TREF curves due to the same active species. Scanning electron microscopy (SEM showed that porous ethylene/α-olefin copolymers with varied surface morphology were obtained from the POPs-supported metallocene catalysts with different pore structure.

  20. Fe-Mediated Nitrogen Fixation with a Metallocene Mediator: Exploring pKa Effects and Demonstrating Electrocatalysis.

    Science.gov (United States)

    Chalkley, Matthew J; Del Castillo, Trevor J; Matson, Benjamin D; Peters, Jonas C

    2018-04-18

    Substrate selectivity in reductive multi-electron/proton catalysis with small molecules such as N2, CO2, and O2 is a major challenge for catalyst design, especially where the competing hydrogen evolution reaction (HER) is thermo-dynamically and kinetically competent. In this study, we investigate how the selectivity of a tris(phosphine)borane iron(I) catalyst, P3BFe+, for catalyzing the nitrogen reduction reaction (N2RR, N2-to-NH3 conversion) versus HER changes as a function of acid pKa. We find that there is a strong correlation between pKa and N2RR efficiency. Stoi-chiometric studies indicate that the anilinium triflate acids employed are only compatible with the formation of ear-ly stage intermediates of N2 reduction (e.g., Fe(NNH) or Fe(NNH2)) in the presence of the metallocene reductant Cp*2Co. This suggests that the interaction of acid and reductant is playing a critical role in N-H bond forming reac-tions. DFT studies identify a protonated metallocene species as a strong PCET donor and suggest that it should be capable of forming the early stage N-H bonds critical for N2RR. Furthermore, DFT studies also suggest that the observed pKa effect on N2RR efficiency is attributable to the rate and thermodynamics, of Cp*2Co protonation by the different anilinium acids. Inclusion of Cp*2Co+ as a co-catalyst in controlled potential electrolysis experiments leads to improved yields of NH3. The data presented provide what is to our knowledge the first unambiguous demonstration of electrocatalytic nitrogen fixation by a molecular catalyst (up to 6.7 equiv NH3 per Fe at -2.1 V vs Fc+/0).

  1. Investigation into paramagnetic metallocenes and diarene transition element complexes by magnetic resonance methods

    International Nuclear Information System (INIS)

    Solodovnikov, S'P.

    1982-01-01

    Data on study of EPR- and NMR-spectra of paramagnetic metal-locenes and diarene transition element complexes are presented. Analysis of g-factors, constants of superthin and spin-spin interactions in the EPR spectra, as well as paramagnetic shifts in the NMR spectra has been used to establish electron configuration of the complexes. Manifestation of Jahn-Feller effect in EPR spectra of sandwich compounds is described. Scheme of d-electron equations in metallocenes and mechanizm of spin delocalization are discussed

  2. Trends in charge transfer and spin alignment of metallocene on graphene

    Science.gov (United States)

    Li, Yuanchang; Chen, Xiaobin; Zhou, Gang; Duan, Wenhui; Kim, Youngkuk; Kim, Minsung; Ihm, Jisoon

    2011-05-01

    By using the first-principles calculations, geometric, electronic, and magnetic properties of metallocene deposited on graphene are systematically investigated. Among all the metallocenes studied, only cobaltocene exhibits obvious charge transfer. Relatively delocalized e1 orbitals of cobaltocene are responsible for n-type doping of graphene or nanoribbons, as well as for the spin-polarized current along the cobaltocene chains. We also propose that, based on our total energy calculations, cobaltocene may be used as a sensor to detect pentagonal defects in graphene by taking advantage of the rotation of cobaltocene’s axis when located above pentagonal defects.

  3. Direct measurement of interaction forces between a platinum dichloride complex and DNA molecules.

    Science.gov (United States)

    Muramatsu, Hiroshi; Shimada, Shogo; Okada, Tomoko

    2017-09-01

    The interaction forces between a platinum dichloride complex and DNA molecules have been studied using atomic force microscopy (AFM). The platinum dichloride complex, di-dimethylsulfoxide-dichloroplatinum (II) (Pt(DMSO) 2 Cl 2 ), was immobilized on an AFM probe by coordinating the platinum to two amino groups to form a complex similar to Pt(en)Cl 2 , which is structurally similar to cisplatin. The retraction forces were measured between the platinum complex and DNA molecules immobilized on mica plates using force curve measurements. The histogram of the retraction force for λ-DNA showed several peaks; the unit retraction force was estimated to be 130 pN for a pulling rate of 60 nm/s. The retraction forces were also measured separately for four single-base DNA oligomers (adenine, guanine, thymine, and cytosine). Retraction forces were frequently observed in the force curves for the DNA oligomers of guanine and adenine. For the guanine DNA oligomer, the most frequent retraction force was slightly lower than but very similar to the retraction force for λ-DNA. A higher retraction force was obtained for the adenine DNA oligomer than for the guanine oligomer. This result is consistent with a higher retraction activation energy of adenine with the Pt complex being than that of guanine because the kinetic rate constant for retraction correlates to exp(FΔx - ΔE) where ΔE is an activation energy, F is an applied force, and Δx is a displacement of distance.

  4. Energy dependence of `molecular rocket reaction` in modified metallocene - cyclodextrin inclusion compound and comparison with those in other systems

    Energy Technology Data Exchange (ETDEWEB)

    Matsue, H. [Tohoku Univ., Sendai (Japan). Dept. of Chemistry; Yamaguchi, I. [Tohoku Univ., Sendai (Japan). Dept. of Chemistry; Sekine, T. [Tohoku Univ., Sendai (Japan). Dept. of Chemistry; Yoshihara, K. [Tohoku Univ., Sendai (Japan). Dept. of Chemistry

    1995-11-01

    `Molecular rocket reaction` was confirmed in modified metallocene-{beta}-cyclodextrin(CD) inclusion compound for the first time. Energy dependence of the reaction was examined in the range between 100 eV and several tens keV. The curve revealed at least an order of 0.5% of rocket survival probability below 126 eV and a nearly constant value ({approx}0.2%) above 130 eV. The energy dependence curve was discussed in relation to those in metal {beta}-diketonates, phtalocyanines, metallocenes and normal metallocene-{beta}-CD inclusion compounds. (orig.)

  5. Energy dependence of 'molecular rocket reaction' in modified metallocene -cyclodextrin inclusion compound and comparison with those in other systems

    International Nuclear Information System (INIS)

    Matsue, H.; Yamaguchi, I.; Sekine, T.; Yoshihara, K.

    1995-01-01

    'Molecular rocket reaction' was confirmed in modified metallocene-β-cyclodextrin(CD) inclusion compound for the first time. Energy dependence of the reaction was examined in the range between 100 eV and several tens keV. The curve revealed at least an order of 0.5% of rocket survival probability below 126 eV and a nearly constant value (∼0.2%) above 130 eV. The energy dependence curve was discussed in relation to those in metal β-diketonates, phtalocyanines, metallocenes and normal metallocene-β-CD inclusion compounds. (orig.)

  6. Solvation energy of metallocenes pilot ions: Beyond the Born approximation

    International Nuclear Information System (INIS)

    Krishtalik, Lev I.

    2008-01-01

    Determination of the single-ion transfer energies demands for some extrathermodynamic assumption on the solvation energy of the pilot ion. Here, the factors affecting solvation energies of the metallocenes pilot ions are explored. The dielectric response energies for these ions in several organic solvents obey the predictions of the local continuum electrostatics. The dielectric response of water reveals to be anomalously large due to the effect of dipoles' correlation caused by hydrogen bonds. The effect of this nonlocal response has been estimated from the data on redox potentials in aqueous-organic solvents as equal to ∼0.09-0.10 eV. The second reason for deviation of solvation energy from the simple picture of continuum electrostatics lies in the preferable orientation of water molecules with H atoms towards the neutral solute creating a positive intraphase potential. The determination of this potential based on experimental data has been done. Its value for ferrocene in water is estimated as ∼+0.1 V. This figure is in accordance with the value which one could expect from the MD simulations in the framework of the polarizable force field model. The list of the single-ion transfer energies based on the improved ferrocene-ferricenium standard is given

  7. Hot atom reactions in neutron irradiated solid iron group metallocenes

    International Nuclear Information System (INIS)

    Yassine, T.; Blackburn, R.

    1990-01-01

    Investigation of the hot reactions of the recoil metal nuclides in neutron irradiated solid ferrocene, ruthenocene and osmocene shows that the retention decreases from ferrocene to osmocene. This observation is ascribed to the effects of recoil energy and the size of the hot zone. The large isotope effect observed between osmium isotopes and between ruthenium isotopes are explained as resulting from the effect of the Auger ionisation produced by internal conversion which takes place in Os-185 and Ru-97 to a greater degree than in their other isotopes. Irradiation of solid metallocenes diluted with an inert solid (silica) showed that the retention in ruthenocene is high and only slightly less than for the pure case whilst the retention of osmocene is very small and the retention of ferrocene is almost zero. The high retention in solid diluted ruthenocene was tentatively attributed to a combination of primary retention resulting from γ cancellation and uptake of recoil momentum by the solid lattice. (author) 15 refs. 5 tabs. 2 figs

  8. Synthesis and Antitumor Activity of New Group 3 Metallocene Complexes.

    Science.gov (United States)

    Caporale, Angelamaria; Palma, Giuseppe; Mariconda, Annaluisa; Del Vecchio, Vitale; Iacopetta, Domenico; Parisi, Ortensia Ilaria; Sinicropi, Maria Stefania; Puoci, Francesco; Arra, Claudio; Longo, Pasquale; Saturnino, Carmela

    2017-03-28

    The quest for alternative drugs with respect to the well-known cis -platin and its derivatives, which are still used in more than 50% of the treatment regimens for patients suffering from cancer, is highly needed. In this context, organometallic compounds, which are defined as metal complexes containing at least one direct covalent metal-carbon bond, have recently been found to be promising anticancer drug candidates. A series of new metallocene complexes with scandium, yttrium, and neodymium have been prepared and characterized. Some of these compounds show a very interesting anti-proliferative activity in triple negative breast cancer cell line (MDA.MB231) and the non-hormone sensitive prostate cancer cell line (DU145). Moreover, the interaction of some of them with biological membranes, evaluated using liposomes as bio-membrane mimetic model systems, seems to be relevant. The biological activity of these compounds, particularly those based on yttrium, already effective at low concentrations on both cancer cell lines, should be taken into account with regard to new therapeutic approaches in anticancer therapy.

  9. [sup 129]I Moessbauer spectroscopic study of metallocene-iodine adducts

    Energy Technology Data Exchange (ETDEWEB)

    Nakashima, Satoru (Dept. of Chemistry, Faculty of Science, Hiroshima Univ. (Japan)); Sakai, Hiroshi (Dept. of Chemistry, Faculty of Science, Hiroshima Univ. (Japan)); Watanabe, Masanobu (Dept. of Chemistry, Coll. of Arts and Sciences, Univ. of Tokyo (Japan)); Maeda, Yutaka (Research Reactor Inst., Kyoto Univ., Osaka (Japan))

    1994-05-01

    A [sup 129]I Moessbauer spectroscopic study of iodine adducts of ferrocenophane, biruthenocene, and osmocene is reported. The spectra show the existence of iodine bonded to the central metals of metallocenes in addition to triiodide anions. The valence state of iron in the ferrocenophane-iodine adduct is the same as those of ruthenium and osmium in their adducts. (orig.)

  10. Highly tunable porous organic polymer (POP) supports for metallocene-based ethylene polymerization

    Science.gov (United States)

    Wang, Xiong; Li, Zhenyou; Han, Xiaoyu; Han, Zhengang; Bai, Yongxiao

    2017-10-01

    Porous organic Polymers (POPs) can not only exhibit high specific surface area and pore volume, but also tunable pore size distribution. Herein, copolymers of 2-hydroxyethylmethylacrylate (HEMA) and divinylbenzene (DVB) with specific pore structure were synthesized via a dispersion polymerization strategy, and then immobilized metallocene catalysts with well-defined pore structure were obtained on the produced POP supports. The nitrogen sorption and Gel permeation chromatography (GPC) results demonstrate that the pore structure of the immobilized metallocene catalyst is highly dependent on the pore structure of the POPs, and the pore structure of metallocene catalysts or the POPs has a significant influence on the molecular chain growth of the produced polyethylene. By tuning the distribution of the active species scattered in the micro- and the narrow meso-pore range (roughly ≤4 nm), the chain growth of the polyolefin can be tailored effectively during the polymerization process, although differential scanning calorimetry (DSC) and temperature rising elution fractionation (TREF) results show that the chemical composition distributions (CCDs) of produced PE from the POPs-supported metallocene catalysts are not determined by polymerization activity or molecule chain length, but mainly by the active site species scattered in the supported catalysts. Scanning electron micrograph (SEM) shows that the produced polyethylene has highly porous fabric which consists of nanofiber and spherical beads of micron dimension.

  11. Rheological characterization and modeling of linear and branched metallocene polypropylenes prepared by reactive processing

    Czech Academy of Sciences Publication Activity Database

    Pivokonský, Radek; Zatloukal, M.; Filip, Petr; Tzoganakis, C.

    2009-01-01

    Roč. 156, 1-2 (2009), s. 1-6 ISSN 0377-0257 R&D Projects: GA AV ČR IAA200600703 Institutional research plan: CEZ:AV0Z20600510 Keywords : Melt strength * Metallocene polypropylene * Elongational viscosity Subject RIV: BK - Fluid Dynamics Impact factor: 2.000, year: 2009

  12. Si-H Bond Activation of Alkynylsilanes by Group 4 Metallocene Complexes

    Czech Academy of Sciences Publication Activity Database

    Lamač, Martin; Spannenberg, A.; Baumann, W.; Jiao, H.; Fischer, Ch.; Hansen, S.; Arndt, P.; Rosenthal, U.

    2010-01-01

    Roč. 132, č. 12 (2010), s. 4369-4380 ISSN 0002-7863 Institutional research plan: CEZ:AV0Z40400503 Keywords : Si-H bond activation * alkynylsilanes * metallocene complexes Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 9.019, year: 2010

  13. Intramolecular activation of a pendant nitrile group in Ti and Zr metallocene complexes

    Czech Academy of Sciences Publication Activity Database

    Horáček, Michal; Gyepes, Robert; Císařová, I.; Pinkas, Jiří; Kubišta, Jiří; Lamač, Martin

    2015-01-01

    Roč. 787, JUL 2015 (2015), s. 56-64 ISSN 0022-328X R&D Projects: GA ČR(CZ) GA14-08531S Institutional support: RVO:61388955 Keywords : metallocene * titanium * zirconium Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.336, year: 2015

  14. Synthesis and characterization of calcium hydroxy and fluoroapatite functionalized with methyl phosphonic dichloride

    Energy Technology Data Exchange (ETDEWEB)

    Agougui, Hassen; Aissa, Abdallah [Laboratoire de Physico-Chimie des Materiaux, Faculte des Sciences de Monastir, 5019 Monastir (Tunisia); Debbabi, Mongi, E-mail: m.debbabi@yahoo.fr [Laboratoire de Physico-Chimie des Materiaux, Faculte des Sciences de Monastir, 5019 Monastir (Tunisia)

    2012-11-15

    Highlights: Black-Right-Pointing-Pointer Surface reactivity of apatites toward methyl phosphonic dichloride is tested. Black-Right-Pointing-Pointer Chemical analysis shows that hydroxyapatite is more reactive. Black-Right-Pointing-Pointer NMR spectra show the formation of Ca-O-P{sub org} and P{sub inorg}-O-P{sub org} bonds. Black-Right-Pointing-Pointer AFM indicated that the texture surface was changed by grafting. - Abstract: The nature of apatite-organic molecule interaction was the subject of many investigations. Grafting the organic molecule onto the inorganic support may precede through either formation of covalent bonds or ionic interaction between superficial hydroxyl on the apatite surface and organic functions. The hybrid materials obtained by functionalization of apatite surfaces with phosphonate moieties are of interest for their potential applications such in catalysis, chromatography and biomedical domain. In this scope, calcium hydroxyl and fluoroapatite (CaHAp and CaFAp) were prepared in the presence of the methyl phosphonic dichloride (MPO), by contact method in organic solvent at 25 Degree-Sign C for 2 days. The products are rigorously characterized by chemical analysis, infrared (IR), MAS-NMR spectroscopies, powder X-ray diffraction (XRD), atomic force microscopy (AFM) and specific surface area (SSA). The X-ray powder analysis showed that the crystallinity was sensibly affected by the presence of organic moieties. The IR spectroscopy showed new vibration modes appearing related to phosphonate groups essentially at 2930, 1315, 945, 764 and 514 cm{sup -1}. The {sup 31}P MAS NMR spectrum for hydroxy and fluoroapatite exhibits a single signal at 2.8 ppm. After reaction with (MPO) the spectra show the presence of new signals, assigned to the formation of organic-inorganic bond between the superficial hydroxyl groups of the apatite ({identical_to}CaOH) and ({identical_to}POH) and methyl phosphonic dichloride. The SSA decreases with increasing

  15. Anionic tantalum(V) bis(dicarbollide) complexes with bent-metallocene structures

    Energy Technology Data Exchange (ETDEWEB)

    Uhrhammer, R.; Su, Yue-Xin; Swenson, D.C.; Jordan, R.F. [Univ. of Iowa, Iowa City, IA (United States)

    1994-09-14

    Bis(dicarbollide) complexes {eta}{sup 5}-C{sub 2}B{sub 9}H{sub 11}){sub 2}M which adopt ferrocene-type metallocene structures are well known. However, ({eta}{sup 5}-C{sub 2}B{sub 9}H{sub 11}){sub 2}MX{sub n} species with bent metallocene structures are comparitively rare and are limited to the f-block metals. Key examples include Raymond`s dianionic U(IV) complex ({eta}{sup 5}-C{sub 2}B{sub 9}H{sub 11}){sub 2}UCl{sub 2}{sup 2-2} and a series of lanthanide complexes ({eta}{sup 5}-C{sub 2}B{sub 9}H{sub 11}){sub 2}Ln(THF){sup n-} (n = 2, Y; n = 1, Zr, Hf) complexes which adopt bent-metallocene structures. For several years, the authors have been investigating the possibility of exploiting carborane ligands in the construction of electrophilic early transition metal alkyl systems, and they have reported on a series of mixed-ring bent-metallocene (C{sub 5}-Me{sub 5})(C{sub 2}B{sub 9}H{sub 11})M(R) (M = Zr, Hf) and (C{sub 5}H{sub 4}R)(C{sub 2}B{sub 9}H{sub 11})TaX{sub 2} (R = H, Me) species. During the course of this work, the authors prepared a series of anionic tantalum (V) bis(dicarbollide) complexes, ({eta}{sup 5}-C{sub 2}B{sub 9}H{sub 11}){sub 2}TaX{sub 2}- (X = C1 (1), Me (2), F (3)), which adopt bent-metallocene structures. The synthesis and characterization of these compounds are discussed in this contribution.

  16. Ethylenediammonium dichloride

    Directory of Open Access Journals (Sweden)

    Milad Gabro

    2009-06-01

    Full Text Available The title ionic compound, C2H10N22+·2Cl−, crystallizes with a center of symmetry within the cation. Each of the positively charged ammonium ends of the molecule is trigonally hydrogen bonded to three different chloride counter-ions, while each of the chloride ions is trigonally hydrogen bonded to three different ethylenediammonium cations. The hydrogen-bonding network leads to stabilization of the structure.

  17. Synthesis, solid and solution studies of paraquat dichloride calixarene complexes. Molecular modelling

    Energy Technology Data Exchange (ETDEWEB)

    Garcia S, I.; Ramirez, F. M., E-mail: flor.ramirez@inin.gob.m [ININ, Departamento de Quimica, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico)

    2010-07-01

    The interaction of the herbicide paraquat dichloride (P Q, substrate) with p-tert-butylcalix arenas (L, receptor) was investigated in both the solution and solid states. The isolated paraquat calixarene complexes were characterised by UV-visible, {sup 1}H NMR, ESI-Ms, Luminescence and IR spectroscopies and elemental analysis. The stoichiometry of complexes 1 and 2 was 1:1 (1 herbicide: 1 calixarene) and both revealed a biexponential luminescence decay with lifetimes depending on the size and the conformational particularity of the calixarenes. Molecular modelling suggested that both calixarenes interact with the herbicide through cation-{pi} interaction. P Q in included in the p-tert butylcalix a rene cavity, a situation favoured by its pinched conformation in polar solvent while it is partially included in the p-tert butylcalix a rene cavity because of its in-out cone conformation. The theoretical results, in particular using Mopac procedures, were in agreement with the experimental findings. (Author)

  18. Synthesis, solid and solution studies of paraquat dichloride calixarene complexes. Molecular modelling

    International Nuclear Information System (INIS)

    Garcia S, I.; Ramirez, F. M.

    2010-01-01

    The interaction of the herbicide paraquat dichloride (P Q, substrate) with p-tert-butylcalix arenas (L, receptor) was investigated in both the solution and solid states. The isolated paraquat calixarene complexes were characterised by UV-visible, 1 H NMR, ESI-Ms, Luminescence and IR spectroscopies and elemental analysis. The stoichiometry of complexes 1 and 2 was 1:1 (1 herbicide: 1 calixarene) and both revealed a biexponential luminescence decay with lifetimes depending on the size and the conformational particularity of the calixarenes. Molecular modelling suggested that both calixarenes interact with the herbicide through cation-π interaction. P Q in included in the p-tert butylcalix a rene cavity, a situation favoured by its pinched conformation in polar solvent while it is partially included in the p-tert butylcalix a rene cavity because of its in-out cone conformation. The theoretical results, in particular using Mopac procedures, were in agreement with the experimental findings. (Author)

  19. Nucleophilic reactions of hydrazido(2-) complexes of molybdenum and tungsten with succinyl dichloride and phenyl isocyanate

    International Nuclear Information System (INIS)

    Iwanami, Kiyotaka; Mizobe, Yasushi; Takahashi, Tamotsu; Kodama, Teruyuki; Uchida, Yasuzo

    1981-01-01

    Nucleophilic attack of the WNNH 2 group in the hydrazido(2-) complex [WF(NNH 2 )(dpe) 2 ][BF 4 ] (dpe = Ph 2 PCH 2 CH 2 PPh 2 ) on succinyl dichloride gives a novel ethanedioylhydrazido(2-) complex, [WF(NNCOCH 2 CH 2 CO)(dpe) 2 ][BF 4 ]. X-Ray structural analysis shows that the carbon, nitrogen, and oxygen atoms of the ethanedioylhydrazido(2-) ligand lie nearly in the same plane, indicating sp 2 character of the nitrogen atom bearing the two carbonyl groups. Phenyl isocyanate also undergoes nucleophilic attack by the hydrazido(2-) complex [MBr(NNH 2 )(dpe) 2 ]Br (M = Mo or W) to yield the phenylsemicarbazido(2-) type complex, [MBr(NNHCONHPh)(dpe) 2 ]Br. Treatment of the semicarbazido(2-) complex with triethylamine gives a new diazenido complex [MBr(NNCONHPh)(dpe) 2 ]. (author)

  20. Modeling the structure and vibrational spectra for oxouranium dichloride monomer and dimer

    Science.gov (United States)

    Umreiko, D. S.; Shundalau, M. B.; Trubina, O. V.

    2010-11-01

    Structural models are designed and spectral characteristics are computed for the monomer and dimer of the oxouranium dichloride (UOCl2) molecule based on ab initio calculations. The calculations were carried out in the LANL2DZ effective core potential approximation for the uranium atom and all-electron basis sets using DFT methods for oxygen and chlorine atoms (B3LYP/cc-pVDZ). A close-to-planar Y-shaped equilibrium configuration with Cs symmetry is obtained for the UOCl2 monomer. The formation of the dimer is accompanied by both significant changes in the structure of the monomeric fragments and the actual loss of their identities. The obtained spectral characteristics are analyzed and compared with experimental data. The adequacy of the proposed models and qualitative agreement between calculation and experiment are demonstrated.

  1. Mercuric dichloride induces DNA damage in human salivary gland tissue cells and lymphocytes

    Energy Technology Data Exchange (ETDEWEB)

    Schmid, Katharina; Kroemer, Susanne [University of Regensburg, Regensburg (Germany); Sassen, Andrea [University of Regensburg, Department of Pathology, Regensburg (Germany); Staudenmaier, Rainer [Technical University of Munich, Department of Otorhinolaryngology, Head and Neck Surgery, Munich (Germany); Reichl, Franz-Xaver [University of Munich, Institute of Pharmacology and Toxicology, Munich (Germany); Harreus, Ulrich [University of Munich, Department of Otorhinolaryngology, Head and Neck Surgery, Munich (Germany); Hagen, Rudolf; Kleinsasser, Norbert [University of Wuerzburg, Department of Otorhinolaryngology, Head and Neck Surgery, Wuerzburg (Germany)

    2007-11-15

    Amalgam is still one of the most frequently used dental filling materials. However, the possible adverse effects especially that of the mercuric component have led to continued controversy. Considering that mercury may be released from amalgam fillings into the oral cavity and also reach the circulating blood after absorption and resorption, it eventually may contribute to tumorigenesis in a variety of target cells. The present investigation focuses on genotoxic effects below a cytotoxic dose level of mercuric dichloride (HgCl{sub 2}) in human samples of salivary glands and lymphocytes to elucidate a possible role in tumor initiation. DNA migration due to single strand breaks, alkali labile sites and incomplete excision repair was quantified with the aid of the single cell microgel electrophoresis (Comet) assay. The concepts of Olive Tail Moment, percentage of DNA in the Tail and Tail Length were used as measures of DNA damage. To control for cytotoxic effects, the trypan blue exclusion test was applied. Human samples of the parotid salivary gland and lymphocytes of ten donors were exposed to HgCl{sub 2} concentrations from 1 to 50 {mu}M. N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) and dimethyl sulfoxide (DMSO) served as controls. Increasing dose-dependent DNA migration could be demonstrated after exposure to HgCl{sub 2} in cells of the salivary glands and lymphocytes. In both cell types a significant increase in DNA migration could be shown starting from HgCl{sub 2} concentrations of 5 {mu}M in comparison to the negative control. The viability of the cell systems was not affected except at the highest concentration (50 {mu}M) tested. These data indicate genotoxic effects of mercuric dichloride in human salivary glands and lymphocytes at concentrations not leading to cytotoxic effects or cell death. Consequently, a contributory role in oral salivary gland tumor initiation warrants further investigation. (orig.)

  2. Trivalent metallocene chemistry of some uranium, titanium, and zirconium complexes

    International Nuclear Information System (INIS)

    Lukens, W.W. Jr.

    1995-05-01

    Dicyclopentadienyluranium halide dimers have been prepared and their solution behavior examined. These molecules exist as dimers in solution, and the halide ligands undergo rapid site exchange on the NMR timescale above 50 C. Analogous dicyclopentadienyluranium hydroxide dimers have also been prepared; they oxidatively eliminate hydrogen to give the corresponding oxide dimers. Mechanism of this reaction is consistent with αmigration of one of the hydroxide hydrogen atoms to a uranium center followed by elimination of hydrogen. Ground state of [(Me 3 Si) 2 C 5 H 3 ] 3 M M = Nd, U and their base adducts has been examined by variable temperature magnetic susceptibility and EPR spectroscopy. The ground state is found to be 4 I 9/2 with a crystal field state consisting largely of J z = 1/2 lowest, in agreement with previous studies on tris-cyclopentadienylneodymium complexes. The zirconium metallocene Cp 3 Zr has been prepared, characterized crystallographically, and its reactivity studied. Its chemical behavior is controlled by presence of an electron in the non-bonding, d z 2 orbital which prevents formation of base adducts Of Cp 3 Zr, but allows Cp 3 Zr to abstract atoms from other molecules. Electonic and EPR spectra of Cp* 2 TiX complexes, where Cp* is Me 5 C 5 and X is a monodentate, anionic ligand such as halide, have been studied. A π-bonding spectrochemical series is developed, and trends in π-bonding ability are found similar to those in other inorganic complexes. The β-agostic interactions in Cp* 2 TiN(Me)Ph have been examined using variable temperature EPR spectroscopy, and the enthalpy/entropy of the interaction determined. In Cp* 2 TiEt, enthalpy of the β-agostic interaction is -1.9 kcal/mol. The titanocene anion, Cp* 2 TiLi(TMEDA) (TMEDA is N,N,N',N'-tetramethylethylenediamine), has been prepared and its structure determined

  3. Slow Magnetic Relaxation in a Dysprosium Ammonia Metallocene Complex.

    Science.gov (United States)

    Demir, Selvan; Boshart, Monica D; Corbey, Jordan F; Woen, David H; Gonzalez, Miguel I; Ziller, Joseph W; Meihaus, Katie R; Long, Jeffrey R; Evans, William J

    2017-12-18

    We report the serendipitous discovery and magnetic characterization of a dysprosium bis(ammonia) metallocene complex, [(C 5 Me 5 ) 2 Dy(NH 3 ) 2 ](BPh 4 ) (1), isolated in the course of performing a well-established synthesis of the unsolvated cationic complex [(C 5 Me 5 ) 2 Dy][(μ-Ph) 2 BPh 2 ]. While side reactivity studies suggest that this bis(ammonia) species owes its initial incidence to impurities in the DyCl 3 (H 2 O) x starting material, we were able to independently prepare 1 and its tetrahydrofuran (THF) derivative, [(C 5 Me 5 ) 2 Dy(NH 3 )(THF)](BPh 4 ) (2), from the reaction of [(C 5 Me 5 ) 2 Dy][(μ-Ph) 2 BPh 2 ] with ammonia in THF. The low-symmetry complex 1 exhibits slow magnetic relaxation under zero applied direct-current (dc) field to temperatures as high as 46 K and notably exhibits an effective barrier to magnetic relaxation that is more than 150% greater than that previously reported for the [(C 5 Me 5 ) 2 Ln][(μ-Ph) 2 BPh 2 ] precursor. On the basis of fitting of the temperature-dependent relaxation data, magnetic relaxation is found to occur via Orbach, Raman, and quantum-tunneling relaxation processes, and the latter process can be suppressed by the application of a 1400 Oe dc field. Field-cooled and zero-field-cooled dc magnetic susceptibility measurements reveal a divergence at 4 K indicative of magnetic blocking, and magnetic hysteresis was observed up to 5.2 K. These results illustrate the surprises and advantages that the lanthanides continue to offer for synthetic chemists and magnetochemists alike.

  4. Assessment of occurrence and concentrations of paraquat dichloride in water, sediments and fish from Warri River Basin, Niger Delta, Nigeria.

    Science.gov (United States)

    Ikpesu, Thomas Ohwofasa

    2015-06-01

    The distribution of Paraquat dichloride in different matrices of Warri River, Western Niger Delta, Nigeria was examined. The samplings and physicochemical parameters of the river were carried out during the dry and wet seasons, and stations were visited on monthly basis. The downstream stations had significant (p water, the pesticide level was higher in the dry season than in wet season, and there was no significant difference between the seasons (p > 0.05). The reverse was the case for sediments and fish. The physicochemical parameters of the river's water were within the recommended limits accepted by Federal Environmental Protection Agency, Nigeria. The observed Paraquat dichloride concentrations were above ecological bench, an observation that calls for regular monitoring and strict law enforcement to develop a strategy to manage environmental hazards and to improve environmental protection of this area.

  5. Dosimetry of bone metastases in targeted radionuclide therapy with alpha-emitting (223)Ra-dichloride.

    Science.gov (United States)

    Pacilio, Massimiliano; Ventroni, Guido; De Vincentis, Giuseppe; Cassano, Bartolomeo; Pellegrini, Rosanna; Di Castro, Elisabetta; Frantellizzi, Viviana; Follacchio, Giulia Anna; Garkavaya, Tatiana; Lorenzon, Leda; Ialongo, Pasquale; Pani, Roberto; Mango, Lucio

    2016-01-01

    Ra-dichloride is an alpha-emitting radiopharmaceutical used in the treatment of bone metastases from castration-resistant prostate cancer. Image-based dosimetric studies remain challenging because the emitted photons are few. The aim of this study was to implement a methodology for in-vivo quantitative planar imaging, and to assess the absorbed dose to lesions using the MIRD approach. The study included nine Caucasian patients with 24 lesions (6 humeral head lesions, 4 iliac wing lesions, 2 scapular lesions, 5 trochanter lesions, 3 vertebral lesions, 3 glenoid lesions, 1 coxofemoral lesion). The treatment consisted of six injections (one every 4 weeks) of 50 kBq per kg body weight. Gamma-camera calibrations for (223)Ra included measurements of sensitivity and transmission curves. Patients were statically imaged for 30 min, using an MEGP collimator, double-peak acquisition, and filtering to improve the image quality. Lesions were delineated on (99m)Tc-MDP whole-body images, and the ROIs superimposed on the (223)Ra images after image coregistration. The activity was quantified with background, attenuation, and scatter correction. Absorbed doses were assessed deriving the S values from the S factors for soft-tissue spheres of OLINDA/EXM, evaluating the lesion volumes by delineation on the CT images. In 12 lesions with a wash-in phase the biokinetics were assumed to be biexponential, and to be monoexponential in the remainder. The optimal timing for serial acquisitions was between 1 and 5 h, between 18 and 24 h, between 48 and 60 h, and between 7 and 15 days. The error in cumulated activity neglecting the wash-in phase was between 2 % and 12 %. The mean effective half-life (T 1/2eff) of (223)Ra was 8.2 days (range 5.5-11.4 days). The absorbed dose (D) after the first injection was 0.7 Gy (range 0.2-1.9 Gy. Considering the relative biological effectiveness (RBE) of alpha particles (RBE = 5), D RBE = 899 mGy/MBq (range 340-2,450 mGy/MBq). The

  6. Trivalent metallocene chemistry of some uranium, titanium, and zirconium complexes

    Energy Technology Data Exchange (ETDEWEB)

    Lukens, Jr., Wayne Wendell [Univ. of California, Berkeley, CA (United States)

    1995-05-01

    Dicyclopentadienyluranium halide dimers have been prepared and their solution behavior examined. These molecules exist as dimers in solution, and the halide ligands undergo rapid site exchange on the NMR timescale above 50 C. Analogous dicyclopentadienyluranium hydroxide dimers have also been prepared; they oxidatively eliminate hydrogen to give the corresponding oxide dimers. Mechanism of this reaction is consistent with αmigration of one of the hydroxide hydrogen atoms to a uranium center followed by elimination of hydrogen. Ground state of [(Me3Si)2C5H3]3M M = Nd, U and their base adducts has been examined by variable temperature magnetic susceptibility and EPR spectroscopy. The ground state is found to be 4I9/2 with a crystal field state consisting largely of Jz = 1/2 lowest, in agreement with previous studies on tris-cyclopentadienylneodymium complexes. The zirconium metallocene Cp3Zr has been prepared, characterized crystallographically, and its reactivity studied. Its chemical behavior is controlled by presence of an electron in the non-bonding, dz2 orbital which prevents formation of base adducts Of Cp3Zr, but allows Cp3Zr to abstract atoms from other molecules. Electonic and EPR spectra of Cp*2TiX complexes, where Cp* is Me5C5 and X is a monodentate, anionic ligand such as halide, have been studied. A π-bonding spectrochemical series is developed, and trends in π-bonding ability are found similar to those in other inorganic complexes. The β-agostic interactions in Cp*2TiN(Me)Ph have been examined using variable temperature EPR spectroscopy, and the enthalpy/entropy of the interaction determined. In Cp*2TiEt, enthalpy of the β-agostic interaction is -1.9 kcal/mol. The titanocene anion, Cp*2TiLi(TMEDA) (TMEDA is N,N,N`,N`-tetramethylethylenediamine), has been

  7. Properties of metallocene complexes during the oxidative crosslinking of air drying coatings

    Science.gov (United States)

    Stava, Vit; Erben, Milan; Vesely, David; Kalenda, Petr

    2007-05-01

    Driers are added to air drying paints to accelerate the hardening of spread coating. For decades cobalt octoate has been the most widely used drier because of its good performance at ambient temperature. Recently, several reports describing possible carcinogenity and genotoxicity of cobalt and cobalt salts, such as cobalt sulfate in aerosols, have appeared. It is necessary to reduce the amount of cobalt compounds in coatings industry. Present study deals with the possibility of using ferrocene and its derivatives as driers for air drying coatings. We concentrated particularly on the synergic effect between these metallocene complexes and the cobalt drier. In the first step the kinetics of autooxidation by FTIR spectroscopy in model systems was investigated. Then the metallocene complexes were applied together with cobalt drier to alkyd resin, where their influence on hardness of spread coatings was examined.

  8. Solid-state NMR studies of Ziegler-Natta and metallocene catalysts.

    Science.gov (United States)

    Tijssen, Koen C H; Blaakmeer, E S Merijn; Kentgens, Arno P M

    2015-01-01

    Ziegler-Natta catalysts are the workhorses of polyolefin production. However, although they have been used and intensively studied for half a century, there is still no comprehensive picture of their mechanistic operation. New techniques are needed to gain more insight in these catalysts. Solid-state NMR has reached a high level of sophistication over the last few decades and holds great promise for providing a deeper insight in Ziegler-Natta catalysis. This review outlines the possibilities for solid-state NMR to characterize the different components and interactions in Ziegler-Natta and metallocene catalysts. An overview is given of some of the expected mechanisms and the resulting polymer microstructure and other characteristics. In the second part of this review we present studies that have used solid-state NMR to investigate the composition of Ziegler-Natta and metallocene catalysts or the interactions between their components. Copyright © 2015 Elsevier Inc. All rights reserved.

  9. Crosslinking of metallocenic α-olefin propylene copolymers by vacuum gamma irradiation

    International Nuclear Information System (INIS)

    Satti, A.J.; Andreucetti, N.A.; Quijada, R.; Vallés, E.M.

    2012-01-01

    Metallocenic polypropylene and copolymers with 3.7, and 9.2 mol% of hexene and 3.0 mol% of octadecene comonomer content were synthesized without the presence of additives and irradiated with 60 Co gamma radiation under vacuum at room temperature. Size Exclusion Cromatography and gel extraction data showed that scission reactions predominate over crosslinking in the homopolymer and that there is a dose from where crosslinking started to increase considerably, in the irradiated copolymers. Rheology also showed evidence of chain-enlargements on the copolymers by means of an increase in the viscoelastic properties of the irradiated material. - Highlight: ► Vacuum gamma irradiation of metallocenic isotactic propylene copolymers. ► We examine the radioinduced changes in rheological properties and molecular weights. ► Radioinduced crosslinking in the copolymers, without the presence of additives. ► Dependence of crosslinking with copolymer′s length and amount of short branches.

  10. Coordination of molecular nitrogen to metallocenes of 3d-series elements at low temperatures

    International Nuclear Information System (INIS)

    Grinval'd, I.I.; Lokshin, B.V.; Mar'in, V.P.; Vyshinskij, L.I.; Razuvaev, G.A.

    1987-01-01

    Methods of low-temperature IR spectroscopy are used to study coordination of molecular nitrogen to metallocenes of 3d-series, Cp 2 M (Cp=η 5 -C 5 H 5 ; M=V, Cr, Mn, Fe, Co, Ni). The reaction was carried out by sequent seposition of reagent to cooled substrate (the window of KBr) at 16 and 80 K temperatures. It is stated that a narrow absorption band in the range of 2140 cm -1 , observed in synthesis products at 16 K, belongs to monodentatly coordinated N 2 molecule. Synthesis at 80 K is followed by formation of polymeric bridge structures, that results in pronounced IR spectrum band broadening. On the basis of absorption band intensity analysis concentration of produced adducts is estimated and a series of variation of metallocene ability to addition molecular nitrogen: Cp 2 Fe 2 V 2 Cr approximately Cp 2 Mn 2 Co 2 Ni is determined

  11. Influence of the elastomeric polypropylene addition on the properties of commercial metallocenic polypropylene

    Directory of Open Access Journals (Sweden)

    Maria de Fátima V. Marques

    2001-10-01

    Full Text Available Polypropylene with special properties can be obtained by metallocenic catalysts. These catalytic systems represent the beginning of a new age in polyolefins technology. In this work, the influence of the addition of a syndiotactic polypropylene (s-PP on the processability and mechanical properties of a commercial isotactic polypropylene (i-PP obtained by metallocenic catalysts was evaluated. Increasing addition of s-PP promoted better processability, with an increase in the impact strength and a decrease in the stress at break. A reduction of the crystallinity in the polymeric blends was verified. The more significant influence of the s-PP addition was observed for the mi-PP, compared to the ZNi-PP.

  12. On the triplet nature of excited states of group IVB metallocenes

    International Nuclear Information System (INIS)

    Lukova, G.V.; Smirnov, V.A.; Starodubova, S.E.

    2005-01-01

    Direct photophysical approach is presented to estimation of energy and orbital nature of electron-excited states of metalorganic compounds of transition metals (Ti, Zr, Hf) by nonradiating triplet-triplet energy transfer from metalorganic complexes to unsaturated hydrocarbons having strong S-T-splitting energy. It is proved for the first time that emission excites states of metallocenes Cp 2 M IV Cl 2 are triplet and their emission is accordingly phosphorescence [ru

  13. Metallocene catalyzed synthesis of fungistatic vicinal aminoalcohols under solvent free conditions.

    Science.gov (United States)

    Mancilla, Gabriela; Durán-Patrón, Rosa M; Macías-Sánchez, Antonio J; Collado, Isidro G

    2010-11-15

    Group 4 and 5 metallocenes, Cp(2)TiCl(2), Cp(2)ZrCl(2) and Cp(2)VCl(2), have been evaluated as catalyst in the solvent free, room temperature, preparation of vicinal aminoalcohols. The regioselectivity of the reaction and the fungistatic activity of the prepared compounds against Botrytis cinerea and Colletotrichum gloeosporioides are discussed. Copyright © 2010 Elsevier Ltd. All rights reserved.

  14. Activation of C-H bonds by rare-earth metallocene-butyl complexes.

    Science.gov (United States)

    Grindell, Richard; Day, Benjamin M; Guo, Fu-Sheng; Pugh, Thomas; Layfield, Richard A

    2017-09-05

    The stable metallocene-butyl complexes [(Cp Me ) 2 M( n Bu)] 2 (M = Y, Dy) were synthesized and their reactivity towards to ferrocene and bulky N-heterocyclic carbenes investigated. Selective mono-deprotonation of ferrocene and a benzylic methyl group of IMes were observed, whereas a control reaction of (Cp Me ) 3 M with IMes resulted in a normal-to-abnormal NHC rearrangement.

  15. Influence of metallocene substitution on the antibacterial activity of multivalent peptide conjugates.

    Science.gov (United States)

    Hoffknecht, Barbara C; Prochnow, Pascal; Bandow, Julia E; Metzler-Nolte, Nils

    2016-07-01

    Peptide dendrimers and derivatisation of peptides with metallocenes showed promising results in the search for new antibacterial agents. The two concepts are combined in this work leading to multivalent, metallocene-containing peptide derivates. These new peptides were synthesised utilising microwave assisted, copper(I) catalyzed alkyne-azide cycloaddition (CuAAC, "click" chemistry). Twelve new peptide conjugates, containing either a ferrocenoyl group or a ruthenocenoyl group on so-called ultrashort (i.e. < 5 amino acids) peptides, and ranging from monovalent to trivalent conjugates, were synthesised and their antibacterial activity was investigated by minimal inhibitory concentration (MIC) assays on five different bacterial strains. The antibacterial activity was compared to the same peptide conjugates without metallocenes. The resulting MIC values showed a significant enhancement of the antibacterial activity of these peptide conjugates against Gram-positive bacteria by the metallocenoyl groups. Additionally, the compounds with two metallocenoyl groups presented the best antibacterial activities overall. Copyright © 2016 Elsevier Inc. All rights reserved.

  16. In situ synthesis of nanoclay filled polyethylene using polymer supported metallocene catalyst system

    Directory of Open Access Journals (Sweden)

    Z. V. P Murthy

    2011-01-01

    Full Text Available In situ ethylene polymerizations were performed using bis(cyclopentadienetitanium dichloride supported on polyethersulfone as catalyst. The bis(cyclopentadienetitanium dichloride supported on polyethersulfone catalyst activity estimated by ethylene polymerization was 360 kgPE/molTi/h. During polymerization the fillers used were montmorillionite nanoclays having surface modifications with 35-45 wt% dimethyl dialkyl(14-18amine (FA and 25-30 wt% trimethyl stearyl ammonium (FB. These fillers were pretreated with methylaluminoxine (MAO; cocatalyst for better dispersion onto the polymer matrix. The formation of polyethylene within the whole matrix was confirmed by FTIR studies. It was found that the nature of nanofiller did not have any remarkable effect on the melting characteristics of the polymer. TGA study indicates that nanoclay FB filled polyethylene has higher thermal stability than nanoclay FA filled polyethylene. The melting temperature of the obtained polyethylenes was 142 ºC, which corresponds to that synthesized by the polyether sulfone supported catalyst.

  17. Copper-64 Dichloride as Theranostic Agent for Glioblastoma Multiforme: A Preclinical Study

    Directory of Open Access Journals (Sweden)

    Cristina Ferrari

    2015-01-01

    Full Text Available Glioblastoma multiforme (GBM is the most common primary malignant brain tumor in adults with a median survival time less than one year. To date, there are only a limited number of effective agents available for GBM therapy and this does not seem to add much survival advantage over the conventional approach based on surgery and radiotherapy. Therefore, the development of novel therapeutic approaches to GBM is essential and those based on radionuclide therapy could be of significant clinical impact. Experimental evidence has clearly demonstrated that cancer cells have a particularly high fractional content of copper inside the nucleus compared to normal cells. This behavior can be conveniently exploited both for diagnosis and for delivering therapeutic payloads (theranostic of the radionuclide copper-64 into the nucleus of cancerous cells by intravenous administration of its simplest chemical form as dichloride salt [64Cu]CuCl2. To evaluate the potential theranostic role of [64Cu]CuCl2 in GBM, the present work reports results from a preclinical study carried out in a xenografted GBM tumor mouse model. Biodistribution data of this new agent were collected using a small-animal PET tomograph. Subsequently, groups of tumor implanted nude mice were treated with [64Cu]CuCl2 to simulate single- and multiple-dose therapy protocols, and results were analyzed to estimate therapeutic efficacy.

  18. Root bark extracts of Juncus effusus and Paeonia suffruticosa protect salivary gland acinar cells from apoptotic cell death induced by cis-platinum (II) diammine dichloride.

    Science.gov (United States)

    Mukudai, Yoshiki; Kondo, Seiji; Shiogama, Sunao; Koyama, Tomoyuki; Li, Chunnan; Yazawa, Kazunaga; Shintani, Satoru

    2013-12-01

    Cis-platinum (II) diammine dichloride (CDDP) is a platinum-based anticancer agent, and is often used for chemotherapy for malignant tumors, albeit CDDP has serious side-effects, including xerostomia (dry mouth). Since patients with xerostomia have reduced quality of life, it is urgent and important to identify nontoxic and natural agents capable of reducing the adverse effect of chemotherapy on salivary gland function. Therefore, we commenced an institutional collaborative project in which candidates of herbal extracts were selected from more than 400 bioactive herbal products for their potential therapeutic effects not only on xerostomia, but also on oral diseases. In the present study, we report on two Chinese medical herbal extracts from the root barks of Juncus effusus and Paeonia suffruticosa. The two extracts showed a protective effect in NS-SV-Ac cells from the cytotoxicity and apoptosis caused by CDDP. The effect was dependent on the p53 pathway, protein kinase B/Akt 1 and mitochondrial apoptosis-related proteins (i.e. Bcl-2 and Bax), but was not dependent on nuclear factor κB. Notably, the apoptosis-protective effect of the extracts was not observed in adenocystic carcinoma cell lines. Although these extracts have been utilized in traditional Chinese medicine for hundreds of years, there are no reports to our knowledge, on their therapeutic effects on xerostomia. Thus, in the present study, we elucidated the potency of these herbal extracts as novel candidates for xerostomia to improve the quality of life of patients undergoing chemotherapy.

  19. UV induced surface modification on improving the cytocompatibility of metallocene polyethylene.

    Science.gov (United States)

    Jaganathan, Saravana K; Prasath, Mani M

    2018-01-01

    Demand for medical implants is rising day by day as the world becomes the place for more diseased and older people. Accordingly, in this research, metallocene polyethylene (mPE), a commonly used polymer was treated with UV rays for improving its biocompatibility. Scanning electron microscopy (SEM) images confirmed the formation of crests and troughs, which depicts the improvement of surface roughness of mPE substrates caused by UV etching. Accordingly, the contact angle measurements revealed that the wettability of mPE-2.5 J/cm2 (68.09º) and mPE-5 J/cm2 (57.93º) samples were found to be increased compared to untreated mPE (86.84º) indicating better hydrophilicity. Further, the UV treated surface exhibited enhanced blood compatibility as determined in APTT (untreated mPE- 55.3 ± 2.5 s, mPE-2.5 J/cm2 - 76.7 ± 4.1 s and mPE-5 J/cm2 - 112.3 ± 2 s) and PT (untreated mPE - 24.7 ± 1.5 s, mPE- 2.5 J/cm2 - 34.3 ± 1.1 s and mPE-5 J/cm2 - 43 ± 2 s) assay. Moreover, the treated mPE-2.5 J/cm2 (4.88%) and mPE-5 J/cm2 (1.79%) showed decreased hemolytic percentage compared to untreated mPE (15.40%) indicating better safety to red blood cells. Interestingly, the changes in physicochemical properties of mPE are directly proportional to the dosage of the UV rays. UV modified mPE surfaces were found to be more compatible as identified through MTT assay, photomicrograph and SEM images of the seeded 3T3 cell population. Hence UV-modified surface of mPE may be successfully exploited for medical implants.

  20. UV induced surface modification on improving the cytocompatibility of metallocene polyethylene

    Directory of Open Access Journals (Sweden)

    SARAVANA K. JAGANATHAN

    Full Text Available ABSTRACT Demand for medical implants is rising day by day as the world becomes the place for more diseased and older people. Accordingly, in this research, metallocene polyethylene (mPE, a commonly used polymer was treated with UV rays for improving its biocompatibility. Scanning electron microscopy (SEM images confirmed the formation of crests and troughs, which depicts the improvement of surface roughness of mPE substrates caused by UV etching. Accordingly, the contact angle measurements revealed that the wettability of mPE-2.5 J/cm2 (68.09º and mPE-5 J/cm2 (57.93º samples were found to be increased compared to untreated mPE (86.84º indicating better hydrophilicity. Further, the UV treated surface exhibited enhanced blood compatibility as determined in APTT (untreated mPE- 55.3 ± 2.5 s, mPE-2.5 J/cm2 - 76.7 ± 4.1 s and mPE-5 J/cm2 - 112.3 ± 2 s and PT (untreated mPE - 24.7 ± 1.5 s, mPE- 2.5 J/cm2 - 34.3 ± 1.1 s and mPE-5 J/cm2 - 43 ± 2 s assay. Moreover, the treated mPE-2.5 J/cm2 (4.88% and mPE-5 J/cm2 (1.79% showed decreased hemolytic percentage compared to untreated mPE (15.40% indicating better safety to red blood cells. Interestingly, the changes in physicochemical properties of mPE are directly proportional to the dosage of the UV rays. UV modified mPE surfaces were found to be more compatible as identified through MTT assay, photomicrograph and SEM images of the seeded 3T3 cell population. Hence UV-modified surface of mPE may be successfully exploited for medical implants.

  1. Rhodium-catalyzed enantioselective intramolecular C-H silylation for the syntheses of planar-chiral metallocene siloles.

    Science.gov (United States)

    Zhang, Qing-Wei; An, Kun; Liu, Li-Chuan; Yue, Yuan; He, Wei

    2015-06-01

    Reported herein is the rhodium-catalyzed enantioselective C-H bond silylation of the cyclopentadiene rings in Fe and Ru metallocenes. Thus, in the presence of (S)-TMS-Segphos, the reactions took place under very mild conditions to afford metallocene-fused siloles in good to excellent yields and with ee values of up to 97%. During this study it was observed that the steric hindrance of chiral ligands had a profound influence on the reactivity and enantioselectivity of the reaction, and might hold the key to accomplishing conventionally challenging asymmetric C-H silylations. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Cyclic voltammetry of 1,1'-bis(diarylphosphino)metallocenes and their complexes with palladium(II)

    International Nuclear Information System (INIS)

    Gusev, O.V.; Peterlejtner, M.G.; Kal'sin, A.M.; Vologdin, N.V.

    2003-01-01

    Influence of composition of 1,1'-bis(diarylphosphino)metallocenes [M(η 5 -C 5 H 4 PPh 2 ) 2 ] (M = Fe, Ru, Os) and their complexes with palladium(II) on the values of the compounds redox potentials was studied by the method of cyclic voltammetry. It was ascertained that oxidation of undercoordinated ruthenocene occurs via phosphorus atom in one two-electron stage. Palladium(II) complexes with the ligands studied are oxidized via metallocene metal atom and the values of oxidation potentials of similar compounds increase in the series Fe [ru

  3. Synthesis, characterization and x-ray crystal structure of a dimethyltin (IV) dichloride complex of 2-acetylpyridine benzophenone azine

    International Nuclear Information System (INIS)

    Mustaffa Shamsuddin; Md Abu Affan; Ramli Atan

    1998-01-01

    Dimethyltin dichloride react with 2-ac ethylpyridine benzophenone azine (apba) in refluxing dry hexane to give (SnMe 2 Cl 2 (apba)) where the azine ligand acts as a bidentate N-N chelating ligand. The complex has been characterized by IR spectroscopy, 1 H and 13 C NMR spectroscopic data and elemental analyses. The crystal structure of the dimethyltin(IV) derivative has also been determined. Crystals are monoclinic with space group P2(1)/n with cell dimensions: a = 10.1819(3) Armstrong, b = 18.3113(5) Armstrong, c = 12.6451(4) Armstrong

  4. Uptake of Radium-223 Dichloride and Early [18F]NaF PET Response Are Driven by Baseline [18F]NaF Parameters: a Pilot Study in Castration-Resistant Prostate Cancer Patients.

    Science.gov (United States)

    Letellier, Arthur; Johnson, Alison C; Kit, Nicolas How; Savigny, Jean-François; Batalla, Alain; Parienti, Jean-Jacques; Aide, Nicolas

    2017-10-12

    The purpose of this study is to identify predictive factors on baseline [ 18 F]NaF positron emission tomography (PET)/computed tomography (CT) of early response to radium-223 dichloride after 3 cycles of treatment in metastatic castration-resistant prostate cancer patients. Analysis of 152 metastases was performed in six consecutive patients who underwent [ 18 F]NaF PET/CT at baseline and for early monitoring after 3 cycles of radium-223 dichloride. All metastases depicted on whole-body [ 18 F]NaF PET/CT were contoured and CT (density in Hounsfield units, sclerotic, mixed, or lytic appearance) as well as [ 18 F]NaF [maximum standardized uptake value (SUV max ), SUV mean , and lesion volume (V 18F-NaF )] patterns were recorded. Tumor response was defined as percentage change in SUV max and SUV mean between baseline and post-treatment PET. Bone lesions were defined as stable, responsive, or progressive, according to thresholds derived from a recent multicentre test-retest study in [ 18 F]NaF PET/CT. Total [ 18 F]NaF uptake in metastases, defined as MATV × SUV mean , was correlated to uptake of radium-223 on biodistribution scintigraphy performed 7 days after the first cycle of treatment. Among metastases, 116 involved the axial skeleton and 36 the appendicular skeleton. Lesions were sclerotic in 126 cases and mixed in 26 cases. No lytic lesion was depicted. ROC analysis showed that SUV max and SUV mean were better predictors of lesion response than V 18F-NaF and density on CT (P < 0.0001 and P = 0.001, respectively). SUV max and SUV mean were predictors of individual tumor response in separate multivariate models (P = 0.01 and P = 0.02, respectively). CT pattern (mixed versus sclerotic) and lesion density were independent predictors only when assessing response with delta SUV max (P = 0.002 and 0.007, respectively). A good correlation between total [ 18 F]NaF uptake within metastases and their relative radium-223 uptake assessed by two observers 7

  5. A base-free thorium-terminal-imido metallocene: synthesis, structure, and reactivity.

    Science.gov (United States)

    Ren, Wenshan; Zi, Guofu; Fang, De-Cai; Walter, Marc D

    2011-11-04

    The synthesis, structure, and reactivity of a base-free thorium terminal-imido metallocene have been comprehensively studied. Treatment of thorium metallocenes [{η(5)-1,2,4-(Me(3)C)(3)C(5)H(2)}(2)ThMe(2)] and [{η(5)-1,3-(Me(3)C)(2)C(5)H(3)}(2)ThMe(2)] with RNH(2) gives diamides [{η(5)-1,2,4-(Me(3)C)(3)C(5)H(2)}(2)Th(NHR)(2)] (R=Me (7), p-tolyl (8)) and [{η(5)-1,3-(Me(3)C)(2)C(5)H(3)}(2)Th(NH-p-tolyl)(2)] (9), respectively. Diamides 7 and 9 do not eliminate methylamine or p-toluidine, but sublime without decomposition at 150 °C under vacuum (0.01 mmHg), whereas diamide 8 is converted at 140 °C/0.01 mmHg into the primary amine p-tolyl-NH(2) and [{η(5)-1,2,4-(Me(3)C)(3)C(5)H(2)}(2)Th=N(p-tolyl)] (10), which may be isolated in pure form. Imido metallocene 10 does not react with electrophiles such as alkylsilyl halides; however, it reacts with electron-rich or unsaturated reagents. For example, reaction of 10 with sulfur affords the metallacycle [{η(5)-1,2,4-(Me(3)C)(3)C(5)H(2)}(2)Th{N(p-tolyl)S-S}]. Imido 10 is an important intermediate in the catalytic hydroamination of internal alkynes, and an efficient catalyst for the trimerization of PhCN. Density functional theory (DFT) studies provide a detailed understanding of the experimentally observed reactivity patterns. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Binding energies and isomerization in metallocene ions from threshold photoelectron photoion coincidence spectroscopy.

    Science.gov (United States)

    Révész, Agnes; Szepes, László; Baer, Tomas; Sztáray, Bálint

    2010-12-22

    Metallocene ions (Cp(2)M(+), M = Cr, Co, Ni) were studied by threshold photoelectron photoion coincidence spectroscopy (TPEPICO) to investigate the mechanism, energetics, and kinetics of the ionic dissociation processes. The examined energy-selected Cp(2)M(+) ions fragment by losing the neutral cyclopentadienyl ligand. In addition, CH and C(2)H(2) losses appear as minor channels, while the cobaltocene ion also loses an H atom. A possible isomerization pathway has also been observed for Cp(2)Ni(+), yielding a complex with pentafulvalene (C(10)H(8)) with a loss of H(2). In order to determine the 0 K appearance energies for the CpM(+) fragment ions, the asymmetric time-of-flight peak shapes and the breakdown diagrams of the energy-selected metallocene ions were modeled by both the rigid activated complex (RAC) Rice-Ramsperger-Kassel-Marcus (RRKM) theory and the simplified statistical adiabatic channel model (SSACM). The following appearance energies were obtained with SSACM, which is more reliable for loose transition states: 10.57 ± 0.14, 11.01 ± 0.13, and 10.18 ± 0.13 eV for M = Cr, Co, and Ni, respectively. These values combined with the corresponding adiabatic ionization energies yield M-Cp bond dissociation energies in Cp(2)M(+) ions of 5.04 ± 0.16, 5.77 ± 0.15, and 3.96 ± 0.15 eV. Density functional calculations at the B3LYP/6-311G(d,p) level of theory were used to determine the structures of these complexes and to provide parameters necessary for the analysis of the experimental data. The trends in the M-Cp bond energies can be related to the electronic structures of the metallocene ions based on a simple molecular orbital picture.

  7. A base-free thorium-terminal-imido metallocene: synthesis, structure, and reactivity

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Wenshan; Zi, Guofu; Fang, De-Cai [Department of Chemistry, Beijing Normal University (China); Walter, Marc D. [Institut fuer Anorganische und Analytische Chemie, Technische Universitaet Braunschweig (Germany)

    2011-11-04

    The synthesis, structure, and reactivity of a base-free thorium terminal-imido metallocene have been comprehensively studied. Treatment of thorium metallocenes [{η"5-1,2,4-(Me_3C)_3C_5H_2}{sub 2}ThMe{sub 2}] and [{η"5-1,3-(Me_3C)_2C_5H_3}{sub 2}ThMe{sub 2}] with RNH{sub 2} gives diamides [{η"5-1,2,4-(Me_3C)_3C_5H_2}{sub 2}Th(NHR){sub 2}] (R=Me (7), p-tolyl (8)) and [{η"5-1,3-(Me_3C)_2C_5H_3}{sub 2}Th(NH-p-tolyl){sub 2}] (9), respectively. Diamides 7 and 9 do not eliminate methylamine or p-toluidine, but sublime without decomposition at 150 C under vacuum (0.01 mmHg), whereas diamide 8 is converted at 140 C/0.01 mmHg into the primary amine p-tolyl-NH{sub 2} and [{η"5-1,2,4-(Me_3C)_3C_5H_2}{sub 2}Th=N(p-tolyl)] (10), which may be isolated in pure form. Imido metallocene 10 does not react with electrophiles such as alkylsilyl halides; however, it reacts with electron-rich or unsaturated reagents. For example, reaction of 10 with sulfur affords the metallacycle [{η"5-1,2,4-(Me_3C)_3C_5H_2}{sub 2}Th{N(p-tolyl)S-S}]. Imido 10 is an important intermediate in the catalytic hydroamination of internal alkynes, and an efficient catalyst for the trimerization of PhCN. Density functional theory (DFT) studies provide a detailed understanding of the experimentally observed reactivity patterns. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  8. Permethylated metallocenes as suitable models for obtaining the onium mono- and dications

    International Nuclear Information System (INIS)

    Rybinskaya, M.I.; Krejndlin, A.Z.; Khoffmann, R.; Minyaev, R.M.

    1994-01-01

    Permethylated metallocenes of iron sub-group (M = Fe, Ru, Os) have been considered as suitable models for obtaining the onium mono- and dications. EHM MO calculation of charge distribution in monocations, homoannular and heteroannular dications has shown that the positive charge is localized mainly at the metal atom. This fact was confirmed by X-ray studies, IR, 1 H and 13 C NMR spectral and electrochemical data. Reactivity of monocations has been studied. It is shown that M-C(α) σ-bond is realized in mono- and dications under investigation. 36 refs.; 3 tabs

  9. Catalytic dehydrogenation of dimethylamine borane by group 4 metallocene alkyne complexes and homoleptic amido compounds.

    Science.gov (United States)

    Beweries, Torsten; Hansen, Sven; Kessler, Monty; Klahn, Marcus; Rosenthal, Uwe

    2011-08-14

    Dehydrogenation of Me(2)NH·BH(3) (1) by group 4 metallocene alkyne complexes of the type Cp(2)M(L)(η(2)-Me(3)SiC(2)SiMe(3)) [Cp = η(5)-cyclopentadienyl; M = Ti, no L (2Ti); M = Zr, L = pyridine (2Zr)] and group 4 metal amido complexes of the type M(NMe(2))(4) [M = Ti (8Ti), Zr (8Zr)] is presented. This journal is © The Royal Society of Chemistry 2011

  10. Broadening of molecular weight distribution of polymers synthesized by metallocene-based dual-site catalysts

    International Nuclear Information System (INIS)

    Santos, Joao H.Z. dos; Fisch, Adriano G.; Cardozo, Nilo S.M.; Secchi, Argimiro R.

    2008-01-01

    The main topics related to the use of dual-site catalysts in the production of polymers with broad molecular weight distribution are reviewed. The polymerization using dual-site catalysts is more economical and allows to produce a higher quality product than other processes, such as polymer blend and multistage reactors. However, the formulation of these catalysts is quite complicated since the same catalyst must produce distinct polymer grades. In addition, the release of patents concerning the combination of metallocenes and new technologies for polymerization shows that polymerization processes using dual-site catalysts are of current industrial interest. (author)

  11. Oscillating spin-density pattern in gold metallocene and phthalocyanine molecules

    Science.gov (United States)

    Carrascal, Diego; Fernández-Seivane, Lucas; Ferrer, Jaime

    2009-11-01

    We present a theoretical study of the magnetic properties of the spin-1/2 dicyclopentadienyl metallocene (MCp2) and phthalocyanine molecules that contain the transition-metal atoms M=Co , Cu, and Au. We find that the spin-density pattern of gold molecules shows a fully delocalized and oscillating behavior. This spin pattern is to be contrasted with the well-known cases of cobalt or iron molecules, where the magnetic moment is strongly localized at the transition-metal ion.

  12. Conformational analysis and vibrational circular dichroism study of a chiral metallocene catalyst

    Science.gov (United States)

    Merten, Christian; Amkreutz, Marc; Hartwig, Andreas

    2010-04-01

    Metallocene complexes are an important type of catalysts for several applications. In the present work, the Ziegler-Natta-catalyst dichloro[( S, S)-ethylenebis(4,5,6,7-tetrahydro-1-indenyl)] zirconium(IV) is investigated using vibrational circular dichroism (VCD) spectroscopy and density functional theory (DFT) calculations. Furthermore the influence of a different central ion as well as different counterions is examined theoretically. From the comparison of the experimental and calculated VCD spectra, it is concluded that the metal ion acts as a placeholder whose function is just to keep the conformation of the ligand in a chiral shape.

  13. 1H and 13C NMR spectra of metallocene derivatives of bi-and trivalent rare earths

    International Nuclear Information System (INIS)

    Sulejmanov, G.Z.; Bogachev, Yu.S.; Petrovskij, P.V.; Kazimirchuk, E.I.; Zhuravleva, I.L.; Mekhdiev, R.Yu.; Agdamskij, T.A.; Kolobova, N.E.; Beletskaya, I.P.

    1989-01-01

    Using 1 H and 13 C NMR spectroscopy of metallocene lanthanide-containg derivatives of iron, manganese, rhenium and molybdenum, the interaction character of cyclopentadienyl ligand, central metal atom (Re,Mo) with lanthanide atom is studied. The introduction of bivalent ytterbium-containing substituent both over cyclopentadienyl ring and transition metal atom is realized according to σ-type

  14. Non-metallocene rare-earth organometallic derivatives: synthesis, structure and application in the catalysis of transformations of unsaturated substrates

    International Nuclear Information System (INIS)

    Trifonov, A A

    2007-01-01

    The post-metallocene period of development of the chemistry of rare-earth organometallic compounds is analysed. The synthesis, structures and reactivities of complexes containing metal-carbon and metal-hydrogen bonds and stabilised by N-, P, and O-donor ligands are considered. The catalytic activities of these compounds in alkene polymerisation, hydroamination, hydrosilylation and hydroboration are discussed.

  15. Non-metallocene rare-earth organometallic derivatives: synthesis, structure and application in the catalysis of transformations of unsaturated substrates

    Energy Technology Data Exchange (ETDEWEB)

    Trifonov, A A [G.A. Razuvaev Institute of Organometallic Chemistry, Russian Academy of Sciences, Nizhnii Novgorod (Russian Federation)

    2007-11-30

    The post-metallocene period of development of the chemistry of rare-earth organometallic compounds is analysed. The synthesis, structures and reactivities of complexes containing metal-carbon and metal-hydrogen bonds and stabilised by N-, P, and O-donor ligands are considered. The catalytic activities of these compounds in alkene polymerisation, hydroamination, hydrosilylation and hydroboration are discussed.

  16. Non-metallocene rare-earth organometallic derivatives: synthesis, structure and application in the catalysis of transformations of unsaturated substrates

    Science.gov (United States)

    Trifonov, A. A.

    2007-11-01

    The post-metallocene period of development of the chemistry of rare-earth organometallic compounds is analysed. The synthesis, structures and reactivities of complexes containing metal-carbon and metal-hydrogen bonds and stabilised by N-, P, and O-donor ligands are considered. The catalytic activities of these compounds in alkene polymerisation, hydroamination, hydrosilylation and hydroboration are discussed.

  17. Thermal decomposition studies of the polyhedral oligomeric silsesquioxane, POSS h, and when it is impregnated with the metallocene bis(η 5-cyclopentadienyl)zirconium (IV) dichloride or immobilized on silica

    Science.gov (United States)

    Bianchini, D.; Butler, I. S.; Barsan, M. M.; Martens, W.; Frost, R. L.; Galland, G. B.; dos Santos, J. H. Z.

    2008-11-01

    Thermal decomposition studies of the free polyhedral oligomeric silsesquioxane, POSS h, and when this compound has been impregnated with Cp 2ZrCl 2 (Cp = η 5-C 5H 5) or immobilized on SiO 2 were conducted using infrared emission spectroscopy (IES) over a 100-1000 °C temperature range and by thermogravimetric analysis (TGA). The organic groups in POSS h apparently decompose thermally into Si-CH 3, Si-H and other fragments. Upon impregnation with Cp 2ZrCl 2, however, a different thermal decomposition pathway was followed and new infrared emission bands appeared in the 1000-900 cm -1 region suggesting the formation of Si-O-Zr moieties. When immobilized on SiO 2 and subjected to thermal decomposition, the POSS h compound lost its organic groups and the inorganic structure remaining was incorporated into the SiO 2 framework.

  18. 3d Transition Metals and Oxides within Carbon Nanotubes by Co-Pyrolysis of Metallocene & Camphor: High Filling Efficiency and Self-Organized Structures

    OpenAIRE

    Kapoor, Aakanksha; Singh, Nitesh; Dey, Arka Bikash; Nigam, A. K.; Bajpai, Ashna

    2017-01-01

    We demonstrate that a single zone furnace with a modified synthesis chamber design is sufficient to obtain metal (Fe, Co or Ni) filled carbon nanotubes (CNT) with high filling efficiency and controlled morphology. Samples are formed by pyrolysis of metallocenes, a synthesis technique that otherwise requires a dual zone furnace. Respective metallocene in all three cases are sublimed in powder form, a crucial factor for obtaining high filling efficiency. While Fe@CNT is routinely produced using...

  19. Effective half metallocene type titanium complex catalyst for the olefin polymerization; Orefuin jugo ni yukona hafu metarosen gata chitan sakutai shokubai

    Energy Technology Data Exchange (ETDEWEB)

    Nomura, Kotohiro [Nara Institute of Sience and Technology, Nara (Japan)

    1999-10-01

    From the conventional metallocene complex catalyst, ethylene system copolymer of the wide alpha olefin content can efficiently synthesize titanium complex catalyst of the half metallocene type, when it is used. It became clear that the monomer arrangement differed by the substituent on using ligand, when the non-cross-linking complex catalyst was used, while the monomer arrangement of the copolymer was a statistical random array in the cross-linking cyclopentadienyl - amide (CGC) complex catalyst. (NEDO)

  20. Reduction of titanocene dichloride with dysprosium: access to a stable titanocene(ii) equivalent for phosphite-free Takeda carbonyl olefination.

    Science.gov (United States)

    Bousrez, G; Déchamps, I; Vasse, J-L; Jaroschik, F

    2015-05-28

    The reduction of titanocene dichloride with dysprosium yields a new titanocene(ii) equivalent without the need for further stabilising ligands. This reagent can be employed in combination with dithioacetals for the olefination of different carbonyl groups and allows for a simplified all-in-one procedure.

  1. Titanocene Dichloride Complexes Bonded to Carbosilane Dendrimers Via a Spacer of Variable Length – Molecular Dynamics Calculations and Catalysis of Allylic Coupling Reactions

    Czech Academy of Sciences Publication Activity Database

    Strašák, Tomáš; Jaroschik, F.; Malý, M.; Čermák, Jan; Sýkora, Jan; Fajgar, Radek; Karban, Jindřich; Harakat, D.

    2014-01-01

    Roč. 409, SI (2014), s. 137-146 ISSN 0020-1693 R&D Projects: GA MŠk(CZ) LC06070 Grant - others:UJEP(CZ) GA13-06989S Institutional support: RVO:67985858 Keywords : metallodendrimers * titanocene dichloride * allylic homocoupling * molecular dynamics Subject RIV: CC - Organic Chemistry Impact factor: 2.046, year: 2014

  2. The Influence of Ziegler-Natta and Metallocene Catalysts on Polyolefin Structure, Properties, and Processing Ability

    Directory of Open Access Journals (Sweden)

    Ahmad Shamiri

    2014-07-01

    Full Text Available 50 years ago, Karl Ziegler and Giulio Natta were awarded the Nobel Prize for their discovery of the catalytic polymerization of ethylene and propylene using titanium compounds and aluminum-alkyls as co-catalysts. Polyolefins have grown to become one of the biggest of all produced polymers. New metallocene/methylaluminoxane (MAO catalysts open the possibility to synthesize polymers with highly defined microstructure, tacticity, and steroregularity, as well as long-chain branched, or blocky copolymers with excellent properties. This improvement in polymerization is possible due to the single active sites available on the metallocene catalysts in contrast to their traditional counterparts. Moreover, these catalysts, half titanocenes/MAO, zirconocenes, and other single site catalysts can control various important parameters, such as co-monomer distribution, molecular weight, molecular weight distribution, molecular architecture, stereo-specificity, degree of linearity, and branching of the polymer. However, in most cases research in this area has reduced academia as olefin polymerization has seen significant advancements in the industries. Therefore, this paper aims to further motivate interest in polyolefin research in academia by highlighting promising and open areas for the future.

  3. The Influence of Ziegler-Natta and Metallocene Catalysts on Polyolefin Structure, Properties, and Processing Ability

    Science.gov (United States)

    Shamiri, Ahmad; Chakrabarti, Mohammed H.; Jahan, Shah; Hussain, Mohd Azlan; Kaminsky, Walter; Aravind, Purushothaman V.; Yehye, Wageeh A.

    2014-01-01

    50 years ago, Karl Ziegler and Giulio Natta were awarded the Nobel Prize for their discovery of the catalytic polymerization of ethylene and propylene using titanium compounds and aluminum-alkyls as co-catalysts. Polyolefins have grown to become one of the biggest of all produced polymers. New metallocene/methylaluminoxane (MAO) catalysts open the possibility to synthesize polymers with highly defined microstructure, tacticity, and steroregularity, as well as long-chain branched, or blocky copolymers with excellent properties. This improvement in polymerization is possible due to the single active sites available on the metallocene catalysts in contrast to their traditional counterparts. Moreover, these catalysts, half titanocenes/MAO, zirconocenes, and other single site catalysts can control various important parameters, such as co-monomer distribution, molecular weight, molecular weight distribution, molecular architecture, stereo-specificity, degree of linearity, and branching of the polymer. However, in most cases research in this area has reduced academia as olefin polymerization has seen significant advancements in the industries. Therefore, this paper aims to further motivate interest in polyolefin research in academia by highlighting promising and open areas for the future. PMID:28788120

  4. Preparation of tetraphenyl substituted disiloxane bridged ansa-metallocene and investigation of its polymerization properties

    Energy Technology Data Exchange (ETDEWEB)

    Jung, J.H.; Noh, S.K. [Yeungnam University, Kyongsan (Korea, Republic of); Lee, H.B.; Park, S.K.; Lee, D.H. [Kyungpook National University, Taegu (Korea, Republic of); Kang, K.S. [Hanwha Group Research Engineering Center, Taejon (Korea, Republic of)

    1999-03-01

    The tetraphenyl substituted disiloxane bridged ansa-zirconocene has been generated to probe the effect of bridging ligand on metallocene polymerization. The indicated zirconocene has been synthesized by the reaction of ZrCl{sub 4} with the distannylated precursor compound. The new disiloxane bridged ansa-metallocene was characterized by {sup 1}H and {sup 13}C NMR< mass analysis, and elemental analysis. Thylene polymerization was carried out to investigate the polymerization properties of the prepared complex. Polymerization experiments exhibited that the catalytic activity increases with the increase in polymerization temperature as well as the amount of cocatalyst. On the other hand, the molecular weights of the polymers decreased with the increase in polymerization temperature. It turned out that tetraphenyl replacement caused about 50 to 70% activity reduction. The most important feature associated in tetramethyl to tetraphenyl substitution was that molecular weights of the polymers from the tetraphenyl substituted complex were enormously improved comparing to those of the polymers from the tetramethyl one. 9 refs., 1 fig., 1 tab.

  5. Unexpected formation and crystal structure of tetrakis(1H-pyrazole-κN2palladium(II dichloride

    Directory of Open Access Journals (Sweden)

    Thomas Wagner

    2014-12-01

    Full Text Available The title salt, [Pd(C3H4N24]Cl2, was obtained unexpectedly by the reaction of palladium(II dichloride with equimolar amounts of 1-chloro-1-nitro-2,2,2-tris(pyrazolylethane in methanol solution. The Pd2+ cation is located on an inversion centre and has a square-planar coordination sphere defined by four N atoms of four neutral pyrazole ligands. The average Pd—N distance is 2.000 (2 Å. The two chloride anions are not coordinating to Pd2+. They are connected to the complex cations through N—H...Cl hydrogen bonds. In addition, C—H...Cl hydrogen bonds are observed, leading to a three-dimensional linkage of cations and anions.

  6. Intravenous application of HI-6 salts (dichloride and dimethansulphonate) in pigs: comparison with pharmacokinetics profile after intramuscular administration.

    Science.gov (United States)

    Zdarova Karasova, Jana; Zemek, Filip; Kunes, Martin; Kvetina, Jaroslav; Chladek, Jaroslav; Jun, Daniel; Bures, Jan; Tachecí, Ilja; Kuca, Kamil

    2013-01-01

    Oxime HI-6 is an acetylcholinesterase reactivator therapeutically efficient against nerve agents. Because of their physico-chemical properties, oximes are typically applied intramuscularly (i.m.). This route of administration has also some disadvantages, and alternative strategies ought to be examined. We evaluated the pharmacokinetic profiles of two HI-6 salts after their intravenous (i.v.) administration, and compare the results with the known pharmacokinetics after i.m. administration. Pigs were administered with HI-6 salts (i.v), either HI-6 dichloride (10.71 mg/kg) or molar equivalent HI-6 dimethansulphonate (13.59 mg/kg). Doses of the HI-6 salts corresponded with a standard HI-6 dichloride dose in one autoinjector (500 mg) and were recalculated for one kilogram of body weight. The main pharmacokinetic parameters are comparable after i.v. and i.m. HI-6 administration. The compared pharmacokinetic parameters were half-life, terminal rate constant, mean residence time of the molecule in the body, clearance, and the apparent volume in the terminal phase. The bioavailability after i.m. administration was comparable with that of i.v.; these results suggest that the oxime is well released from the muscle depot. Significant differences were found in parameters Cmax and Tmax which are important in cases of emergency when rapidity and bioavailability are paramount for the success of treatment. I.v. administration should solve the problem of rapid clearance. Infusion or bolus administration may be considered as a logical subsequent step in oxime treatment strategy. The main advantage is in maintenance of an effective therapeutic plasma concentration, a more easily achievable effective therapeutic concentration, and fewer local adverse reactions.

  7. Immobilized Bis-Indenyl Ligands for Stable and Cost-Effective Metallocene Catalysts of Hydrogenation and Polymerization Reactions

    Science.gov (United States)

    Simerly, Thomas Max

    Reactions of catalytic hydrogenations and polymerizations are widely used in industry for manufacture of fine chemicals, pharmaceuticals, and plastics. Homogeneous catalysts for the processes that have low stability and their separation is difficult. Therefore, the development of new highly active and stable catalysts for hydrogenations and polymerizations is a necessity. The objective of this research was the development of a strategy for immobilization of heterogeneous metallocene catalysts. First, a methodology of immobilization of bis-indenyl ligands on the surface of mesoporous silica gel was designed. Four bis-indenyl ligands containing functionalized tethers of various lengths with terminal alkene groups were synthesized. All bis-indenyl ligands were immobilized on the surface of mesoporous functionalized silica gel by two methods: hydrosilylation and thiol-ene coupling of the double bond. After comparing the results, the second strategy was chosen as more efficient. The materials can be used further as intermediates for synthesis of supported metallocene catalysts.

  8. Spin transport properties of single metallocene molecules attached to single-walled carbon nanotubes via nickel adatoms

    Science.gov (United States)

    Wei, Peng; Sun, Lili; Benassi, Enrico; Shen, Ziyong; Sanvito, Stefano; Hou, Shimin

    2011-06-01

    The spin-dependent transport properties of single ferrocene, cobaltocene, and nickelocene molecules attached to the sidewall of a (4,4) armchair single-walled carbon nanotube via a Ni adatom are investigated by using a self-consistent ab initio approach that combines the non-equilibrium Green's function formalism with the spin density functional theory. Our calculations show that the Ni adatom not only binds strongly to the sidewall of the nanotube, but also maintains the spin degeneracy and affects little the transmission around the Fermi level. When the Ni adatom further binds to a metallocene molecule, its density of states is modulated by that of the molecule and electron scattering takes place in the nanotube. In particular, we find that for both cobaltocene and nickelocene the transport across the nanotube becomes spin-polarized. This demonstrates that metallocene molecules and carbon nanotubes can become a promising materials platform for applications in molecular spintronics.

  9. Synthesis and structural nvestigation into bivalent lanthanide metallocene derivatives by PMR spectroscopy

    International Nuclear Information System (INIS)

    Sulejmanov, G.Z.; Bogachev, Yu.S.; Abdullaeva, L.T.; Zhuravleva, I.L.; Khalilov, Kh.S.; Rybakova, L.F.; Shapet'ko, N.N.; Beletskaya, I.P.

    1984-01-01

    The nature of the interaction of mercury- and lanthanide (Sm, Eu, Yb) atoms with cyclopentadienyl (CPD) ring in ferrocene and cimantrene derivatives is studied by the PMR method. It is shown that the introduction of mercury and ytterbium into the cyclopentadienyl rings of ferrocene and cimantrene leads to chemical shift displacement of α-protons of the substituted CPD ring to the weak feld, which testifies to electron-acceptor ability of these metals. The conclusion is drawn on similarity of the nature of the ytterbium- and mercury atom interaction with the cyclopentadienyl ring. The techniques are presented for the synthesis of metallocene derivatives of bivalent mercury and lanthanides in tetrahydrofuran at 20 deg C which ensure the 16% yield in preparing [C 5 H 5 FeC 5 H 4 ]L2 YbxC 4 H 8 O and the 78% yield in preparing [(OC) 3 MnC 5 H 4 ] 2 YbxC 4 H 8 O

  10. Metallocene-based polyolefin foams: effects of oxidative irradiation on mechanical properties

    International Nuclear Information System (INIS)

    Bhatt, Chinmay U.; Khan, Saad A.; Hwang, C. Robin

    1998-01-01

    Metallocene-based polyolefin (MPO) foams are being considered for a wide range of applications because of their uniform composition and low toxicity. In this study, stress relaxation and dynamic rheological experiments are used to probe the effects of oxidative irradiation on the structure and final properties of these novel MPO foams. Experiments conducted on irradiated foams of two different densities reveal significantly different behavior. Gamma irradiation of the lighter foam causes structural degradation due to chain scission reactions. This is manifested in faster stress relaxation rates and lower values of elastic moduli and gel fraction in the irradiated samples. The incorporation of O 2 into the polymer backbone, verified by FTIR analysis, confirms the hypothesis of chain scission occurring at the labile peroxide linkages. In contrast, the denser foam shows a small amount of cross-linking and a concomitant improvement in mechanical properties after oxidative irradiation

  11. Metallocene-based polyolefin foams: effects of oxidative irradiation on mechanical properties

    Energy Technology Data Exchange (ETDEWEB)

    Bhatt, Chinmay U.; Khan, Saad A. [Department of Chemical Engineering, North Carolina State University, Raleigh, NC (United States); Hwang, C. Robin [Becton Dickinson Technologies, Research Triangle Park, NC (United States)

    1998-11-01

    Metallocene-based polyolefin (MPO) foams are being considered for a wide range of applications because of their uniform composition and low toxicity. In this study, stress relaxation and dynamic rheological experiments are used to probe the effects of oxidative irradiation on the structure and final properties of these novel MPO foams. Experiments conducted on irradiated foams of two different densities reveal significantly different behavior. Gamma irradiation of the lighter foam causes structural degradation due to chain scission reactions. This is manifested in faster stress relaxation rates and lower values of elastic moduli and gel fraction in the irradiated samples. The incorporation of O{sub 2} into the polymer backbone, verified by FTIR analysis, confirms the hypothesis of chain scission occurring at the labile peroxide linkages. In contrast, the denser foam shows a small amount of cross-linking and a concomitant improvement in mechanical properties after oxidative irradiation.

  12. Development of insulation material for DC cables -- Space charge properties of metallocene catalyzed polyethylene

    Energy Technology Data Exchange (ETDEWEB)

    Wang, S.; Fujita, Michitomo; Tanimoto, Gen; Aida, Fumio; Fujiwara, Yasutaka [Showa Electric Wire and Cable Co., Ltd., Kawasaki, Kanagawa (Japan)

    1996-12-31

    Applicability of polyethylene polymerized using a metallocene catalyst to an insulation material for DC power cables has been investigated. The accumulation properties of space charge in a range from room temperature to 90 C was examined using the pulse electroacoustic method. The result indicated that hetero-charge was observed in the vicinity of the surface of sample at increased temperature, and that hetero-space charge produced by activation of an antioxidant added to the sample was increased or decreased with the increase of the temperature of sample. A hetero-charge absorber was added for controlling the hetero-space charge. As a result, hetero-charge was not observed on the sample in a high electric field extending from room temperature to high temperature. It was confirmed that the volume resistivity of sample was increased at high temperature.

  13. A Low-Symmetry Dysprosium Metallocene Single-Molecule Magnet with a High Anisotropy Barrier.

    Science.gov (United States)

    Pugh, Thomas; Chilton, Nicholas F; Layfield, Richard A

    2016-09-05

    The single-molecule magnet (SMM) properties of the isocarbonyl-ligated dysprosium metallocene [Cp*2 Dy{μ-(OC)2 FeCp}]2 (1Dy ), which contains a rhombus-shaped Dy2 Fe2 core, are described. Combining a strong axial [Cp*](-) ligand field with a weak equatorial field consisting of the isocarbonyl ligands leads to an anisotropy barrier of 662 cm(-1) in zero applied field. The dominant thermal relaxation pathways in 1Dy involves at least the fourth-excited Kramers doublet, thus demonstrating that prominent SMM behavior can be observed for dysprosium in low-symmetry environments. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. First structural evidence for multiple alkali metals between sandwich decks in a metallocene.

    Science.gov (United States)

    Jeletic, Matthew; Perras, Frédéric A; Gorelsky, Serge I; Le Roy, Jennifer J; Korobkov, Ilia; Bryce, David L; Murugesu, Muralee

    2012-07-14

    A tetralithio salt (1) derived by treating 1,4-bis(trimethylsilyl)-cyclooctatriene with (n)BuLi serves as the first structural evidence for a multi-alkali metallocene. Single-crystal XRD confirms two Li(+) each asymmetrically bind to η(3) and η(4) between two COT'' rings and two Li(+) terminally bind to η(3). Solid-state NMR studies confirm the presence of two distinct lithium ion sites while the solution NMR studies suggest the formation of an (COT'' dianion) ion-pair in solution. Further treating of the tetralithio salt with NaCl leads to linear sodium polymeric chains. Therefore, simply changing the ionic radius changes the molecular structure.

  15. High-field electrical properties of new LDPE films prepared using metallocene catalyst; Metallocene shokubai ni yori sakuseisareta shinki polyethylene film no kodenkai tokusei

    Energy Technology Data Exchange (ETDEWEB)

    Ishimatsu, K.; Banmongkol, C.; Mori, T.; Mizutani, T. [Nagoya University, Nagoya (Japan); Ishioka, M.

    1998-07-01

    New Low Density Polyethylene (M-LDPE) prepared using metallocene catalyst has narrower composition distribution and molecular weight distributions than Linear-Low Density Polyethylene (LLDPE) using Ziegler catalyst. The authors compared the electrical insulating properties of M-LDPE films and conventional LLDPE films. The high-field current of M-LDPE was found to be lower than that of LLDPE. The difference in current increased with the decrease of temperature. The high-field current was much suppressed in M-LDPE with a low melting point. The impulse breakdown strength of M-LDPE raised with the decrease of temperature. The insulating properties of M-LDPE with a low melting point were improved at 30degC. These results were explained by a fact that M-LDPE with a low melting point includes more low-molecular-weight components. We also discussed the effects of antioxidant on the electrical properties of MLDPE. We compared the electrical conduction and breakdown strength of undoped M-LDPE and antioxidant-doped M-LDPE. The difference of their electrical properties were little. It was found that the excellent properties of M-LDPE do not depend on the effects or antioxidant. 11 refs., 12 figs., 2 tabs.

  16. A general synthetic strategy for the design of new BODIPY fluorophores based on pyrroles with polycondensed aromatic and metallocene substituents.

    Science.gov (United States)

    Schmidt, Elena Yu; Zorina, Nadezhda V; Dvorko, Marina Yu; Protsuk, Nadezhda I; Belyaeva, Kseniya V; Clavier, Gilles; Méallet-Renault, Rachel; Vu, Thanh T; Mikhaleva, Al'bina I; Trofimov, Boris A

    2011-03-07

    BODIPYrrole: A general strategy for the design of novel BODIPY fluorophores based on pyrroles with polycondensed aromatic and metallocene substituents has been developed. The strategy involves the acylation of the condensed substituent and treatment of the acylated derivative (as oxime) with acetylene in MOH/DMSO (M = alkali metal) to give pyrroles that were then used for assembly of the BODIPY fluorophores (see scheme). Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Effects of Electron Beam Irradiation on Binary Polyamide-6 Blends with Metallocene Copolymers

    International Nuclear Information System (INIS)

    Rosales, C.

    2006-01-01

    A versatile way to produce new materials with high Izod impact strength and reduced heat deformations is the irradiation of compatibilized blends. The effect of electron beam irradiation and different types of dispersed phase grafted copolymers on thermal and mechanical properties, and SEM morphology of polyamide-6 (PA-6) blends were investigated. Two metallocene copolymers (mEPDM and mPOE) grafted in-situ with maleic anhydride and two commercial maleated copolymers (EPDM-g-MA and mEPR-g-MA) were employed in binary blends with PA6 as matrix. The blends were prepared by extrusion with a composition of 80 wt. % of PA-6. The influence of the radical or functional groups generated in the grafting and the irradiation processes (25, 50, 100 and 200 kGy) was found by ATR-FTIR. The blends exhibited the characteristic thermal behavior of immiscible systems. All compatibilizers employed influenced the melting and crystallization behavior of the blend components without irradiation and an improvement in interface adhesion was clearly observed by SEM micrographs. The sizes of the dispersed phase in the non-irradiated reactive blends were in agreement with the viscosity ratios of the blend components. High toughness materials were obtained with ethylene-polypropylene-diene (mEPDM) grafted copolymers without significant variations in their thermal properties and Izod impact strength at room temperature and -30 degree with the irradiation doses. However, the toughness of the blends with grafted metallocene polyethylenes was affected by the irradiation doses employed. Therefore, the gel content and tensile properties of the samples depended on the chain scission, crosslinking and/or grafting reactions of the blend components

  18. Bent and linear Uranium(IV) metallocenes with terminal and bridging cyanide ligands

    International Nuclear Information System (INIS)

    Maynadie, J.; Berthet, J.C.; Thuery, P.; Ephritikhine, M.

    2007-01-01

    Treatment of Cp 2 * UI 2 with KCN in thf led to the formation of Cp 2 * U(CN) 2 (2), which further reacted with NR 4 CN to give [Cp 2 * U(CN) 3 ][ NR 4 ] (R = Et, 3; R = n Bu, 3') and [Cp 2 * U(CN) 5 ][NR 4 ] 3 (R = Et, 4; R n Bu, 4'). While the tri-cyanide 3' adopts the familiar bent sandwich configuration, the penta-cyanide 4 is, after the [Cp 2 * U(NCMe) 5 ] 2+ cation, the second example of a linear metallocene resulting from complete saturation of the equatorial girdle. Compound 3' was also obtained by oxidation of the trivalent compound [Cp 2 * U(CN) 3 ][N n Bu 4 ] 2 ; the rapid and reversible electron transfer between the U(III) and U(IV) complexes was revealed by 1 H NMR spectroscopy. The NMR spectra also revealed that 4 is partially dissociated in thf into 3, providing the first example of an equilibrating couple of bent and linear metallocenes [K = 4.24(4) * 10 -5 at 25 C, ΔH = 199(6) kJ mol -1 , and ΔS = 586(20) J mol -1 K -1 ]. The trinuclear compound [Cp 2 * UCl 2 (μ-CN)] 2 Mg(thf) 4 (1) and the 2D polymeric complex [Cp 2 * U(dmf) 3 -(μ-NC) 2 (AgI) 2 ] n (5), which were obtained during initial attempts on the synthesis of 2-4 and uranium- (V) derivatives, exhibit a bent and linear sandwich structure, respectively. (authors)

  19. Solvent dynamical effects in electron transfer: Evaluation of electronic matrix coupling elements for metallocene self-exchange reactions

    Science.gov (United States)

    McManis, George E.; Nielson, Roger M.; Gochev, Alexander; Weaver, Michael J.

    1989-07-01

    The functional dependence of the rate constants for self exchange, k sub ex, for a series of metallocene redox couples to solvent-induced variations in the nuclear frequency factor, nu, engendered by alterations in the longitudinal solvent relaxation time, tau sub L, are utilized to deduce values of the electronic matrix coupling element, H12, for electron exchange. The analysis exploits the sensitivity of the k sub ex tau sub L -1 dependence to the degree of reaction adiabaticity and hence H12 for a given electron exchange reaction. Six metallocene couples are examined: Cp2Co+/o, Cp2Fe+/o (Cp = cyclopentadienyl) and the decamethyl derivatives Cp2Co+/o and Cp2Fe+/o scrutinized previously, additional solvent-dependent k sub ex values for carboxymethyl (cobaltocenium-cobaltocene) (Cp(e)Z Co+/o, e= ester) and hydroxymethyl (ferrocenium-ferrocene) (HMFc+/o.) Kinetic data are examined in 15 solvents, including 11 debye solvents for which it is anticipated that is proportioned to 1/tau sub L. Corrections to k sub ex for the solvent-dependent variations in the barrier height were obtained by corresponding measurements of the optical electron transfer energies for the related binuclear complex biferrocenylacetylene, yielding barrier corrected rate constants, k sub ex. The relationship between H12 superscript o and metallocene electronic structure is briefly discussed. The analysis also enables effective solvent relaxation times for adiabatic barrier crossing in non-Debye media including primary alcohols, to be extracted.

  20. Versatile supramolecular reactivity of zinc-tetra(4-pyridylporphyrin in crystalline solids: Polymeric grids with zinc dichloride and hydrogen-bonded networks with mellitic acid

    Directory of Open Access Journals (Sweden)

    Sophia Lipstman

    2009-12-01

    Full Text Available Crystal engineering studies confirm that the zinc-tetra(4-pyridylporphyrin building block reveals versatile supramolecular chemistry. In this work, it was found to be reactive in the assembly of both (a a 2D polymeric array by a unique combination of self-coordination and coordination through external zinc dichloride linkers and (b an extended heteromolecular hydrogen-bonded network with mellitic acid sustained by multiple connectivity between the component species.

  1. Dosimetry of bone metastases in targeted radionuclide therapy with alpha-emitting {sup 223}Ra-dichloride

    Energy Technology Data Exchange (ETDEWEB)

    Pacilio, Massimiliano [Azienda Ospealiera San Camillo Forlianini, Rome (Italy). Dept. of Medical Physics; Ventroni, Guido; Mango, Lucio [Azienda Ospealiera San Camillo Forlianini, Rome (Italy). Dept. of Nuclear Medicin; De Vincentis, Giuseppe; Di Castro, Elisabetta; Frantellizzi, Viviana; Follacchio, Giulia Anna; Garkavaya, Tatiana [Rome Univ. (Italy). Dept. of Radiological, Oncological and Anatomo Pathological Sciences; Cassano, Bartolomeo; Lorenzon, Leda [Rome Univ. (Italy). Postgraduate School of Medical Physics; Pellegrini, Rosanna; Pani, Roberto [Rome Univ. (Italy). Dept. of Molecular Medicine; Ialongo, Pasquale [Azienda Ospealiera San Camillo Forlianini, Rome (Italy). Dept. of Radiology

    2016-01-15

    Ra-dichloride is an alpha-emitting radiopharmaceutical used in the treatment of bone metastases from castration-resistant prostate cancer. Image-based dosimetric studies remain challenging because the emitted photons are few. The aim of this study was to implement a methodology for in-vivo quantitative planar imaging, and to assess the absorbed dose to lesions using the MIRD approach. The study included nine Caucasian patients with 24 lesions (6 humeral head lesions, 4 iliac wing lesions, 2 scapular lesions, 5 trochanter lesions, 3 vertebral lesions, 3 glenoid lesions, 1 coxofemoral lesion). The treatment consisted of six injections (one every 4 weeks) of 50 kBq per kg body weight. Gamma-camera calibrations for {sup 223}Ra included measurements of sensitivity and transmission curves. Patients were statically imaged for 30 min, using an MEGP collimator, double-peak acquisition, and filtering to improve the image quality. Lesions were delineated on {sup 99m}Tc-MDP whole-body images, and the ROIs superimposed on the {sup 223}Ra images after image coregistration. The activity was quantified with background, attenuation, and scatter correction. Absorbed doses were assessed deriving the S values from the S factors for soft-tissue spheres of OLINDA/EXM, evaluating the lesion volumes by delineation on the CT images. In 12 lesions with a wash-in phase the biokinetics were assumed to be biexponential, and to be monoexponential in the remainder. The optimal timing for serial acquisitions was between 1 and 5 h, between 18 and 24 h, between 48 and 60 h, and between 7 and 15 days. The error in cumulated activity neglecting the wash-in phase was between 2 % and 12 %. The mean effective half-life (T{sub 1/2eff}) of {sup 223}Ra was 8.2 days (range 5.5-11.4 days). The absorbed dose (D) after the first injection was 0.7 Gy (range 0.2-1.9 Gy). Considering the relative biological effectiveness (RBE) of alpha particles (RBE = 5), D{sub RBE} = 899 mGy/MBq (range 340-2,450 mGy/MBq). The

  2. Introducing metallocene into a triazole peptide conjugate reduces its off-rate and enhances its affinity and antiviral potency for HIV-1 gp120

    Science.gov (United States)

    Gopi, Hosahudya; Cocklin, Simon; Pirrone, Vanessa; McFadden, Karyn; Tuzer, Ferit; Zentner, Isaac; Ajith, Sandya; Baxter, Sabine; Jawanda, Navneet; Krebs, Fred C.; Chaiken, Irwin M.

    2013-01-01

    In this work, we identified a high affinity and potency metallocene-containing triazole peptide conjugate that suppresses the interactions of HIV-1 envelope gp120 at both its CD4 and co-receptor binding sites. The ferrocene-peptide conjugate, HNG-156, was formed by an on-resin copper-catalysed [2 + 3] cycloaddition reaction. Surface plasmon resonance interaction analysis revealed that, compared to a previously reported phenyl-containing triazole conjugate HNG-105 (105), peptide 156 had a higher direct binding affinity for several subtypes of HIV-1 gp120 due mainly to the decreased dissociation rate of the conjugate-gp120 complex. The ferrocene triazole conjugate bound to gp120 of both clade A (92UG037-08) and clade B (YU-2 and SF162) virus subtypes with nanomolar KD in direct binding and inhibited the binding of gp120 to soluble CD4 and to antibodies that bind to HIV-1YU-2 gp120 at both the CD4 binding site and CD4-induced binding sites. HNG-156 showed a close-to nanomolar IC50 for inhibiting cell infection by HIV-1BaL whole virus. The dual receptor site antagonist activity and potency of HNG-156 make it a promising viral envelope inhibitor lead for developing anti-HIV-1 treatments. PMID:18498083

  3. Porous carbon nanospheres derived from chlorination of bis(cyclopentadienyl)titanium dichloride and their electrochemical capacitor performance

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez-Garcia, Pedro, E-mail: pegonzal@quim.ucm.es [Departamento de Quimica Inorganica, Facultad de Ciencias Quimicas, Universidad Complutense, E-28040 Madrid (Spain); Centeno, T.A. [Instituto Nacional del Carbon-CSIC, Apartado 73, E-33080 Oviedo (Spain); Urones-Garrote, Esteban [Centro de Microscopia y Citometria, Universidad Complutense, E-28040 Madrid (Spain); Avila-Brande, David; Otero-Diaz, L. Carlos [Departamento de Quimica Inorganica, Facultad de Ciencias Quimicas, Universidad Complutense, E-28040 Madrid (Spain)

    2011-10-17

    Highlights: {yields} Microporous carbon nanospheres have been produced via chlorination reaction of bis(cyclopentadienyl)titanium dichloride. {yields} The materials present a structure formed by disordered arrangements of graphene-like layers, sp{sup 2}/sp{sup 3} ratio {approx}95-97% and mass-density below pure graphite. {yields} The increase in the reaction temperature decreases the particle size distribution and improves the surface area and the micropore volume. {yields} Electrochemical performance for the 900 deg. C sample shows a specific capacitance of 106 F g{sup -1} in H{sub 2}SO{sub 4} electrolyte and 80 F g{sup -1} in (C{sub 2}H{sub 5}){sub 4}NBF{sub 4}/acetonitrile medium. - Abstract: Conglomerated and accreted porous carbon spheres have been obtained by the chlorination reaction of bis(cyclopentadienyl)titanium dichloride as carbon precursor. The spheres size distribution, derived from scanning electron microscopy observations, shows that the diameter intervals decreases from 70-525 nm at 400 deg. C to 40-370 nm at 900 deg. C. High-resolution transmission electron microscopy observations indicate that the spheres are formed by open and curved randomly stacked graphene-like layers. Electron energy loss spectroscopy studies show relative sp{sup 2}/sp{sup 3} ratio higher than 95% and mass-density values (1.1-1.6 g cm{sup -3}) smaller than graphite. Nitrogen adsorption measurements reveal the presence of micro and mesopores whose contributions to the total porosity greatly depend on the preparation temperature. Galvanostatic charging-discharging measurements on the carbon material synthesized at 900 deg. C provide a specific capacitance of 106 F g{sup -1} in the aqueous H{sub 2}SO{sub 4} electrolyte and 80 F g{sup -1} in the aprotic (C{sub 2}H{sub 5}){sub 4}NBF{sub 4}/acetonitrile medium. These high values suggest the potentiality of this material for electrical energy storage in electrochemical double layer capacitors.

  4. Homogeneous catalytic dehydrocoupling/dehydrogenation of amine-borane adducts by early transition metal, group 4 metallocene complexes.

    Science.gov (United States)

    Sloan, Matthew E; Staubitz, Anne; Clark, Timothy J; Russell, Christopher A; Lloyd-Jones, Guy C; Manners, Ian

    2010-03-24

    The efficient catalytic dehydrocoupling of a range of amine-borane adducts, R'RNH x BH(3) (R' = R = Me 1a; R' = R = (i)Pr 1b; R' = Me, R = CH(2)Ph 1c) by a series of group 4 metallocene type precatalysts has been demonstrated. A reduction in catalytic activity was detected upon descending the group and also on substitution of the cyclopentadienyl (Cp) ligands with sterically bulky or electron-donating substituents. Precatalysts Cp(2)TiCl(2)/2(n)BuLi and Cp(2)Ti(PMe(3))(2), which are believed to act as precursors to [Cp(2)Ti], were found to promote the transformation of 1a to [Me(2)N-BH(2)](2) (3a) in a homogeneous catalytic process. Mechanistic studies identified the linear dimer Me(2)NH-BH(2)-NMe(2)-BH(3) (2a) as a reaction intermediate, which subsequently undergoes further catalytic dehydrogenation to form cyclic dimer 3a. Synthesis of the (2)H-isotopologues of 1a allowed the extraction of phenomenological kinetic isotope effects for 1a --> 2a and 2a --> 3a from initial rate data, which permitted the proposal of a catalytic cycle with plausible intermediates. Support for the presence of an active Ti(II) catalyst was provided by the lack of reactivity of Ti(III) complexes TiCl(3) and Cp(2)TiCl or Ti(0) in the form of THF soluble colloids or bulk Ti powder toward 1a or 1b. Modeling of the rates of consumption of 1a and formation of 3a during catalysis by Cp(2)Ti(PMe(3))(2) supported this conclusion and allowed the proposal of a two cycle, four step reaction mechanism. The proposed first cycle generates 2a in a two step process. In the second cycle, interaction of 2a with the same catalyst then results in a catalytic dehydrogenative ring closing reaction to form 3a, also in a two step process.

  5. Radiation Dose and Hazard Assessment of Potential Contamination Events During Use of 223Ra Dichloride in Radionuclide Therapy.

    Science.gov (United States)

    Stabin, Michael G; Siegel, Jeffry A

    2015-09-01

    An analysis is presented of the possible dosimetric consequences of various potential contamination events involving 223Ra dichloride (Xofigo), the FDA-approved therapeutic agent used in the treatment of bone metastases in patients with castration-resistant prostate cancer. Three exposure scenarios are considered: inhalation dose to an individual due to the hypothetical inhalation of 219Rn and its progeny assumed to be released into the air from a liquid spill on the floor, external dose from direct photon exposure of an individual assigned to clean up a spill, and skin dose to an individual should the liquid material come into contact with their skin. Doses from the first two scenarios were very small; 2.8 × 10(-3) mSv and 8.1 × 10(-4) mSv, respectively. Using extremely conservative assumptions, the skin dose was estimated to be 72 mSv; in a realistic scenario, this dose would likely be an order of magnitude or more lower. These doses are very small compared to regulatory limits, and good health physics practices likely to be employed in such incidents would lower them still further. The authors conclude that the medical use of Xofigo does not pose any significant radiation safety issue with respect to potential contamination events, even if multiple incidents might occur during the course of a year, since all worst-case potential contamination events considered in this study will not result in significant radiation exposures to workers.

  6. Ability of Group IVB metallocene polyethers containing dienestrol to arrest the growth of selected cancer cell lines

    Science.gov (United States)

    2009-01-01

    Background Monomeric Group IVB (Ti, Zr and Hf) metallocenes represent a new class of antitumor compounds. There is literature on the general biological activities of some organotin compounds. Unfortunately, there is little information with respect to the molecular level activity of these organotin compounds. We recently started focusing on the anti-cancer activity of organotin polymers that we had made for other purposes and as part of our platinum anti-cancer effort. Methods For this study, we synthesized a new series of metallocene-containing compounds coupling the metallocene unit with dienestrol, a synthetic, nonsteroidal estrogen. This is part of our effort to couple known moieties that offer antitumor activity with biologically active units hoping to increase the biological activity of the combination. The materials were confirmed to be polymeric using light scattering photometry and the structural repeat unit was verified employing matrix assisted laser desorption ionization mass spectrometry and infrared spectroscopy results. Results The polymers demonstrated the ability to suppress the growth of a series of tumor cell lines originating from breast, colon, prostrate, and lung cancers at concentrations generally lower than those required for inhibition of cell growth by the commonly used antitumor drug cisplatin. Conclusion These drugs show great promise in vitro against a number of cancer cell lines and due to their polymeric nature will most likely be less toxic than currently used metal-containing drugs such as cisplatin. These drugs also offer several addition positive aspects. First, the reactants are commercially available so that additional synthetic steps are not needed. Second, synthesis of the polymer is rapid, occurring within about 15 seconds. Third, the interfacial synthetic system is already industrially employed in the synthesis of aromatic nylons and polycarbonates. Thus, the ability to synthesize large amounts of the drugs is straight

  7. Ability of Group IVB metallocene polyethers containing dienestrol to arrest the growth of selected cancer cell lines

    Directory of Open Access Journals (Sweden)

    Ashida Yuki

    2009-10-01

    Full Text Available Abstract Background Monomeric Group IVB (Ti, Zr and Hf metallocenes represent a new class of antitumor compounds. There is literature on the general biological activities of some organotin compounds. Unfortunately, there is little information with respect to the molecular level activity of these organotin compounds. We recently started focusing on the anti-cancer activity of organotin polymers that we had made for other purposes and as part of our platinum anti-cancer effort. Methods For this study, we synthesized a new series of metallocene-containing compounds coupling the metallocene unit with dienestrol, a synthetic, nonsteroidal estrogen. This is part of our effort to couple known moieties that offer antitumor activity with biologically active units hoping to increase the biological activity of the combination. The materials were confirmed to be polymeric using light scattering photometry and the structural repeat unit was verified employing matrix assisted laser desorption ionization mass spectrometry and infrared spectroscopy results. Results The polymers demonstrated the ability to suppress the growth of a series of tumor cell lines originating from breast, colon, prostrate, and lung cancers at concentrations generally lower than those required for inhibition of cell growth by the commonly used antitumor drug cisplatin. Conclusion These drugs show great promise in vitro against a number of cancer cell lines and due to their polymeric nature will most likely be less toxic than currently used metal-containing drugs such as cisplatin. These drugs also offer several addition positive aspects. First, the reactants are commercially available so that additional synthetic steps are not needed. Second, synthesis of the polymer is rapid, occurring within about 15 seconds. Third, the interfacial synthetic system is already industrially employed in the synthesis of aromatic nylons and polycarbonates. Thus, the ability to synthesize large amounts of

  8. Ability of Group IVB metallocene polyethers containing dienestrol to arrest the growth of selected cancer cell lines

    International Nuclear Information System (INIS)

    Roner, Michael R; Carraher, Charles E Jr; Shahi, Kimberly; Ashida, Yuki; Barot, Girish

    2009-01-01

    Monomeric Group IVB (Ti, Zr and Hf) metallocenes represent a new class of antitumor compounds. There is literature on the general biological activities of some organotin compounds. Unfortunately, there is little information with respect to the molecular level activity of these organotin compounds. We recently started focusing on the anti-cancer activity of organotin polymers that we had made for other purposes and as part of our platinum anti-cancer effort. For this study, we synthesized a new series of metallocene-containing compounds coupling the metallocene unit with dienestrol, a synthetic, nonsteroidal estrogen. This is part of our effort to couple known moieties that offer antitumor activity with biologically active units hoping to increase the biological activity of the combination. The materials were confirmed to be polymeric using light scattering photometry and the structural repeat unit was verified employing matrix assisted laser desorption ionization mass spectrometry and infrared spectroscopy results. The polymers demonstrated the ability to suppress the growth of a series of tumor cell lines originating from breast, colon, prostrate, and lung cancers at concentrations generally lower than those required for inhibition of cell growth by the commonly used antitumor drug cisplatin. These drugs show great promise in vitro against a number of cancer cell lines and due to their polymeric nature will most likely be less toxic than currently used metal-containing drugs such as cisplatin. These drugs also offer several addition positive aspects. First, the reactants are commercially available so that additional synthetic steps are not needed. Second, synthesis of the polymer is rapid, occurring within about 15 seconds. Third, the interfacial synthetic system is already industrially employed in the synthesis of aromatic nylons and polycarbonates. Thus, the ability to synthesize large amounts of the drugs is straight forward

  9. The thermodynamic and structural properties of metallocenes-type random ethylene copolymers

    Energy Technology Data Exchange (ETDEWEB)

    Simanke, Adriane G.; Mauler, Raquel S.; Galland, Griselda B. [Rio Grande do Sul Univ., Porto Alegre, RS (Brazil). Inst. de Quimica]. E-mail: asimanke@portoweb.com.br; Alamo, Rufina G. [Florida State Univ., Tallahassee, FL (UNited States). College of Engineering. Dept. of Chemical Engineering]. E-mail: alamo@eng.fsu.edu

    2001-07-01

    The properties of a series of random ethylene copolymers prepared with the metallocenes catalytic system rac-Et[Ind]{sub 2} ZrCl{sub 2}/MAO were studied for a large variety of comonomer types. These include the classical 1-alkene type with length up to 10 carbons and those of the cyclic type such as cyclopentadiene and dicyclopentadiene. Under rapid crystallization, the melting temperatures of the newly synthesized copolymers followed the relation of model random copolymers indicating a behavior that conforms to that predicted by Flory's phase equilibrium theory. The molar entropy of fusion is not significantly altered by the comonomer type including the dicyclopentadiene type. All types of comonomers studied showed, for a fixed comonomer content, the same change in properties during annealing, except the ethylene 1-butenes. These latter copolymers and the hydrogenated poly butadiene showed a faster rate of change in thermal properties. This is consistent with a higher molecular diffusion for the butene comonomer than for the rest of comonomers analyzed. The properties of the inter lamellar region were also studied as a function of comonomer type and content following the variation of the amorphous halo extracted from the WAXS diffractograms. The observed systematic decrease in the peak scattering angle with increasing comonomer content indicates a variation of the intermolecular liquid structure. (author)

  10. The thermodynamic and structural properties of metallocenes-type random ethylene copolymers

    International Nuclear Information System (INIS)

    Simanke, Adriane G.; Mauler, Raquel S.; Galland, Griselda B.; Alamo, Rufina G.

    2001-01-01

    The properties of a series of random ethylene copolymers prepared with the metallocenes catalytic system rac-Et[Ind] 2 ZrCl 2 /MAO were studied for a large variety of comonomer types. These include the classical 1-alkene type with length up to 10 carbons and those of the cyclic type such as cyclopentadiene and dicyclopentadiene. Under rapid crystallization, the melting temperatures of the newly synthesized copolymers followed the relation of model random copolymers indicating a behavior that conforms to that predicted by Flory's phase equilibrium theory. The molar entropy of fusion is not significantly altered by the comonomer type including the dicyclopentadiene type. All types of comonomers studied showed, for a fixed comonomer content, the same change in properties during annealing, except the ethylene 1-butenes. These latter copolymers and the hydrogenated poly butadiene showed a faster rate of change in thermal properties. This is consistent with a higher molecular diffusion for the butene comonomer than for the rest of comonomers analyzed. The properties of the inter lamellar region were also studied as a function of comonomer type and content following the variation of the amorphous halo extracted from the WAXS diffractograms. The observed systematic decrease in the peak scattering angle with increasing comonomer content indicates a variation of the intermolecular liquid structure. (author)

  11. Physical properties of metallocenes propene-higher α-olefins copolymers

    International Nuclear Information System (INIS)

    Lovisi, Humberto; Santa Maria, Luiz Claudio de; Coutinho, Fernanda M.B.

    2001-01-01

    In this work, new copolymers of propene/1-hexene (PHC) and propene/1-octene (POC) were synthesized by using a highly iso specific metallocenes catalyst system based on rac-Me 2 Si(2-ethyl,4-phenyl,1-indenyl) 2 ZrCl 2 , in the homogeneous and heterogeneous forms, methylaluminoxane (MAO) activated. An investigation about the copolymerization of propene with 1-hexene and 1-octene using this catalyst system illustrates the potential for the tailoring of propene/higher α-olefin copolymers with controlled thermal and mechanical properties by varying the comonomer concentration in the polymerization feed. Both catalyst systems showed high activity and produced random copolymers with very low or no detectable crystallinity. It was observed that properties such as enthalpy of crystallization (ΔHc), crystallization temperature (Tc), melting temperature (Tm), glass transition temperature (Tg) and elastic modulus (E') decreased in a linear pattern with increasing comonomer content in the copolymer. The effect of the short chain branch length was also investigated and it was observed that, compared to 1-hexene, much less 1-octene was necessary to disrupt the crystalline structure and impart rubbery behaviour to the copolymers. (author)

  12. A Dysprosium Metallocene Single-Molecule Magnet Functioning at the Axial Limit.

    Science.gov (United States)

    Guo, Fu-Sheng; Day, Benjamin M; Chen, Yan-Cong; Tong, Ming-Liang; Mansikkamäki, Akseli; Layfield, Richard A

    2017-09-11

    Abstraction of a chloride ligand from the dysprosium metallocene [(Cp ttt ) 2 DyCl] (1 Dy Cp ttt =1,2,4-tri(tert-butyl)cyclopentadienide) by the triethylsilylium cation produces the first base-free rare-earth metallocenium cation [(Cp ttt ) 2 Dy] + (2 Dy ) as a salt of the non-coordinating [B(C 6 F 5 ) 4 ] - anion. Magnetic measurements reveal that [2 Dy ][B(C 6 F 5 ) 4 ] is an SMM with a record anisotropy barrier up to 1277 cm -1 (1837 K) in zero field and a record magnetic blocking temperature of 60 K, including hysteresis with coercivity. The exceptional magnetic axiality of 2 Dy is further highlighted by computational studies, which reveal this system to be the first lanthanide SMM in which all low-lying Kramers doublets correspond to a well-defined M J value, with no significant mixing even in the higher doublets. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Multi-Alkenylsilsesquioxanes as Comonomers and Active Species Modifiers of Metallocene Catalyst in Copolymerization with Ethylene

    Directory of Open Access Journals (Sweden)

    Paweł Groch

    2018-02-01

    Full Text Available The copolymers of ethylene (E with open-caged iso-butyl-substituted tri-alkenyl-silsesquioxanes (POSS-6-3 and POSS-10-3 and phenyl-substituted tetra-alkenyl-silsesquioxane (POSS-10-4 were synthesized by copolymerization over the ansa-metallocene catalyst. The influence of the kind of silsesquioxane and of the copolymerization conditions on the reaction performance and on the properties of the copolymers was studied. In the case of copolymerization of E/POSS-6-3, the positive comonomer effect was observed, which was associated with the influence of POSS-6-3 on transformation of the bimetallic ion pair to the active catalytic species. Functionality of silsesquioxanes and polymerization parameters affected the polyhedral oligomeric silsesquioxanes (POSS contents in the copolymers which varied in the range of 1.33–7.43 wt %. Tri-alkenyl-silsesquioxanes were incorporated into the polymer chain as pendant groups while the tetra-alkenyl-silsesquioxane derivative could act as a cross-linking agent which was proved by the changes in the contents of unsaturated end groups, by the glass transition temperature values, and by the gel contents (up to 81.3% for E/POSS-10-4. Incorporation of multi-alkenyl-POSS into the polymer chain affected also the melting and crystallization behaviors.

  14. Copolymerization of ethylene and cycloolefin with metallocene catalysts : I. Effect of catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Lee, D.H.; Jung, H.K.; Kim, W.S.; Min, K.E.; Park, L.S.; Seo, K.H.; Kang, I.K. [Kyungpook National University, Taegu (Korea); Noh, S.K. [Yeoungnam University, Kyungsan (Korea)

    2000-07-01

    The copolymerization of ethylene (E) and norbornene (N) was examined by using various metallocene catalysts and modified-MAO (MMAO) cocatalyst. For C{sub 2}-symmetry catalysts such as rac-Et(Ind){sub 2}ZrCl{sub 2}, Me{sub 2}Si(Ind){sub 2}ZrCl{sub 2},Me{sub 2}Si(Cp){sub 2}ZrCl{sub 2} and Cs-symmetrical iPr(FluCp)ZrCl{sub 2} as well as CGC and di-bridged zirconocene, the effects of catalyst structure and [N]/[E] feed ratio on catalyst activity, thermal property and [N] content of copolymer (COC) was investigated. For rac-Et(Ind){sub 2}ZrCl{sub 2} catalyst of a constant [N]/[E] feed ratio, the appropriate conditions of [Al]/[Zr] mole ratio, polymerization temperature and cocatalyst structure were found to be 3000, 40 deg. C, MMAO cocatalyst, respectively. As [N]/[E] feed ratio increased. the incorporation of norbornene to copolymer increased while the activity of catalyst decreased except for iPr(FluCp)ZrCl{sub 2}. With consideration of catalyst activity as well as N content, it was found that rac-Et(Ind){sub 2}ZrCl{sub 2}/MMAO system exhibited relatively high activity and controllable T{sub g}. Monomer reactivity ratio was determined by Kelen-Tudos method. (author). 34 refs., 5 tabs., 3 figs.

  15. Thermal and rheological behavior of reactive blends from metallocene olefin elastomers and polypropylene

    Directory of Open Access Journals (Sweden)

    Nei S. Domingues Junior

    2012-01-01

    Full Text Available Reactive blends of metallocene polyolefin elastomers (POE/polypropylene (PP with 60/40 composition were prepared with an organic peroxide, 2,5-dimethyl-2,5-di-(t-butylperoxyhexane, and a bis-azide derivative, diphenyloxid-4,4'-bis(sulfonylazide (BSA. Ethylene-1-butene (EB and ethylene-1-octene (EO copolymers and elastomeric polypropylene (ePP were used as the elastomeric phase. The effect of elastomeric phase on the thermal, rheological, morphological and mechanical properties of the thermoplastic vulcanizates (TPVs or dynamic vulcanizates were studied. All TPVs depicted pseudoplastic behavior and blends cured with azide curative showed higher viscosities. The TPVs showed both dispersed and continuous phase morphology that depends on the elastomeric phase type revealing a limited degree of compatibility between PP and the elastomers EO or EB. On the other hand, the TPV PP/ePP showed a uniform morphology suggesting an improved compatibility. Substantial changes observed in physical properties were explained on the basis of blends' morphology and dynamic vulcanization. The results confirm that the mechanical properties are more influenced by the elastomeric phase than by the curative agent. This study revealed a broad new range of opportunities for POE-based TPVs.

  16. Microwave-assisted surface modification of metallocene polyethylene for improving blood compatibility.

    Science.gov (United States)

    Mohandas, Hemanth; Sivakumar, Gunalan; Kasi, Palaniappan; Jaganathan, Saravana Kumar; Supriyanto, Eko

    2013-01-01

    A wide number of polymers are being used for various medical applications. In this work, microwave-assisted surface modification of metallocene polyethylene (mPE) was studied. FTIR analysis showed no significant changes in the chemical groups after treatment. Contact angle analysis revealed a decrease in contact angle of the treated samples insinuating increasing hydrophilicity and better biocompatibility. Qualitative analysis of treated samples using scanning electron microscope (SEM) depicted increasing surface roughness and holes formation further corroborating the results. Coagulation assays performed for estimating prothrombin time (PT) and activated partial thromboplastin time (APTT) showed an increase in the clotting time which further confirmed the improved blood compatibility of the microwave-treated surfaces. Further, the extent of hemolysis in the treated sample was lower than the untreated one. Hence, microwave-assisted surface modification of mPE resulted in enhanced blood compatibility. Improved blood compatibility of mPE may be exploited for fabrication of artificial vascular prostheses, implants, and various blood contacting devices.

  17. Structures of substituted-cyclopentadienyl uranium(III) dimers and related uranium metallocenes deduced by EXAFS

    International Nuclear Information System (INIS)

    Lukens, W.W. Jr.; Allen, P.G.; Bucher, J.J.; Edelstein, N.M.; Hudson, E.A.; Shuh, D.K.; Reich, T.; Andersen, R.A.

    1999-01-01

    The crystal structures of [Cp double-prime 2 UF] 2 and [Cp double-dagger 2 UO] 2 are reported, where Cp double-prime is 1,3-(Me 3 -Si) 2 C 5 H 3 and Cp double-dagger is 1,3-(Me 3 C) 2 C 5 H 3 . Both complexes have idealized C 2h symmetry, and their U hor-ellipsis U distances are 3.85 and 3.39 angstrom, respectively. The X-ray absorption spectra of several uranium metallocene complexes, and the numerical results from fitting the EXAFS spectra, are reported. For [Cp double-dagger 2 UF] 2 , the U hor-ellipsis U distance was found by EXAFS to be similar to that in [Cp double-prime 2 UF] 2 , implying that [Cp double-dagger 2 UF] 2 is dimeric. A structural model is advanced that correlates the U hor-ellipsis U distance with the orientation of the cyclopentadienyl rings; the orientation is due to a subtle combination of steric repulsions between ligands on the same metal center and between ligands on adjacent metal centers

  18. Enhanced blood compatibility of metallocene polyethylene subjected to hydrochloric acid treatment for cardiovascular implants.

    Science.gov (United States)

    Jaganathan, Saravana Kumar; Mohandas, Hemanth; Sivakumar, Gunalan; Kasi, Palaniappan; Sudheer, Theertha; Avineri Veetil, Sruthi; Murugesan, Selvakumar; Supriyanto, Eko

    2014-01-01

    Blood compatibility of metallocene polyethylene (mPE) was investigated after modifying the surface using hydrochloric acid. Contact angle of the mPE exposed to HCl poses a decrease in its value which indicates increasing wettability and better blood compatibility. Surface of mPE analyzed by using FTIR revealed no significant changes in its functional groups after treatment. Furthermore, scanning electron microscope images supported the increasing wettability through the modifications like pit formations and etching on the acid rendered surface. To evaluate the effect of acid treatment on the coagulation cascade, prothrombin time (PT) and activated partial thromboplastin time (APTT) were measured. Both PT and APTT were delayed significantly (P < 0.05) after 60 min exposure implying improved blood compatibility of the surfaces. Hemolysis assay of the treated surface showed a remarkable decrease in the percentage of lysis of red blood cells when compared with untreated surface. Moreover, platelet adhesion assay demonstrated that HCl exposed surfaces deter the attachment of platelets and thereby reduce the chances of activation of blood coagulation cascade. These results confirmed the enhanced blood compatibility of mPE after HCl exposure which can be utilized for cardiovascular implants like artificial vascular prostheses, implants, and various blood contacting devices.

  19. Ferrocenyl(trihydro)borates: building blocks for the synthesis of heterooligonuclear metallocene complexes.

    Science.gov (United States)

    Reichert, Adelina; Bolte, Michael; Lerner, Hans-Wolfram; Wagner, Matthias

    2013-01-21

    The reaction of [Cp(2)ZrCl(2)] with the lithium salt Li[FcBH(3)] in stoichiometric ratios of 1.5 : 1 or 0.4 : 1 furnishes the mixed-metallocene complexes [Cp(2)(Cl)Zr(H(3)BFc)] (1) and [Cp(2)Zr(H(3)BFc)(2)] (3), respectively (Cp = cyclopentadienyl; Fc = ferrocenyl). When the two reagents are combined in a ratio of 0.6 : 1, complex 1 is formed together with the zirconium hydride species [Cp(2)(H)Zr(H(3)BFc)] (2). Compound 2 can be obtained in pure form from [Cp(2)Zr(H)Cl] and Li[FcBH(3)]. Treatment of the half-sandwich complexes [(C(5)R(5))ZrCl(3)] with 3 equivalents of Li[FcBH(3)] leads to the heterotetranuclear aggregates [(C(5)R(5))Zr(H(3)BFc)(3)] (4: R = H; 5: R = CH(3)). Li(2)[fc(BH(3))(2)] and 3 equivalents of [Cp(2)ZrCl(2)] give the heterotrinuclear compound [fc(BH(3)Zr(Cl)Cp(2))(2)] (6) with bridging ferrocenylene core (fc = 1,1'-ferrocenylene). According to X-ray crystallography, the trihydroborate ions are coordinated in a [Zr(μ-H)(2)B(H)-] fashion in 1, 2, 3 and 6, whereas 4 and 5 are carrying tridentate trihydroborate ligands.

  20. Microwave-Assisted Surface Modification of Metallocene Polyethylene for Improving Blood Compatibility

    Directory of Open Access Journals (Sweden)

    Hemanth Mohandas

    2013-01-01

    Full Text Available A wide number of polymers are being used for various medical applications. In this work, microwave-assisted surface modification of metallocene polyethylene (mPE was studied. FTIR analysis showed no significant changes in the chemical groups after treatment. Contact angle analysis revealed a decrease in contact angle of the treated samples insinuating increasing hydrophilicity and better biocompatibility. Qualitative analysis of treated samples using scanning electron microscope (SEM depicted increasing surface roughness and holes formation further corroborating the results. Coagulation assays performed for estimating prothrombin time (PT and activated partial thromboplastin time (APTT showed an increase in the clotting time which further confirmed the improved blood compatibility of the microwave-treated surfaces. Further, the extent of hemolysis in the treated sample was lower than the untreated one. Hence, microwave-assisted surface modification of mPE resulted in enhanced blood compatibility. Improved blood compatibility of mPE may be exploited for fabrication of artificial vascular prostheses, implants, and various blood contacting devices.

  1. Enhanced Blood Compatibility of Metallocene Polyethylene Subjected to Hydrochloric Acid Treatment for Cardiovascular Implants

    Directory of Open Access Journals (Sweden)

    Saravana Kumar Jaganathan

    2014-01-01

    Full Text Available Blood compatibility of metallocene polyethylene (mPE was investigated after modifying the surface using hydrochloric acid. Contact angle of the mPE exposed to HCl poses a decrease in its value which indicates increasing wettability and better blood compatibility. Surface of mPE analyzed by using FTIR revealed no significant changes in its functional groups after treatment. Furthermore, scanning electron microscope images supported the increasing wettability through the modifications like pit formations and etching on the acid rendered surface. To evaluate the effect of acid treatment on the coagulation cascade, prothrombin time (PT and activated partial thromboplastin time (APTT were measured. Both PT and APTT were delayed significantly (P<0.05 after 60 min exposure implying improved blood compatibility of the surfaces. Hemolysis assay of the treated surface showed a remarkable decrease in the percentage of lysis of red blood cells when compared with untreated surface. Moreover, platelet adhesion assay demonstrated that HCl exposed surfaces deter the attachment of platelets and thereby reduce the chances of activation of blood coagulation cascade. These results confirmed the enhanced blood compatibility of mPE after HCl exposure which can be utilized for cardiovascular implants like artificial vascular prostheses, implants, and various blood contacting devices.

  2. Metallocene-based inhibitors of cancer-associated carbonic anhydrase enzymes IX and XII.

    Science.gov (United States)

    Salmon, Adam J; Williams, Michael L; Wu, Quoc K; Morizzi, Julia; Gregg, Daniel; Charman, Susan A; Vullo, Daniela; Supuran, Claudiu T; Poulsen, Sally-Ann

    2012-06-14

    In this study, 20 metallocene-based compounds comprising extensive structural diversity were synthesized and evaluated as carbonic anhydrase (CA, EC 4.2.1.1) inhibitors. These compounds proved moderate to good CA inhibitors in vitro, with several compounds displaying selectivity for cancer-associated isozymes CA IX and CA XII compared to off-target CA I and CA II. Compound 6 was the most potent ferrocene-based inhibitor with K(i)s of 5.9 and 6.8 nM at CA IX and XII, respectively. A selection of key drug-like parameters comprising Log P, Log D, solubility, and in vitro metabolic stability and permeability were measured for two of the ferrocene-based compounds, regioisomers 1 and 5. Compounds 1 and 5 were found to have characteristics consistent with lipophilic compounds, however, our findings show that the lipophilicity of the ferrocene moiety is not well modeled by replacement with either a naphthyl or a phenyl moiety in software prediction tools.

  3. Synthesis and structural investigation into bivalent lanthanide metallocene derivatives by PMR spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Sulejmanov, G.Z.; Bogachev, Yu.S.; Abdullaeva, L.T.; Zhuravleva, I.L.; Khalilov, Kh.S.; Rybakova, L.F.; Shapet' ko, N.N.; Beletskaya, I.P. (Nauchno-Issledovatel' skij Fiziko-Khimicheskij Inst., Moscow (USSR))

    1984-01-01

    The nature of the interaction of mercury- and lanthanide (Sm, Eu, Yb) atoms with cyclopentadienyl (CPD) ring in ferrocene and cimantrene derivatives is studied by the PMR method. It is shown that the introduction of mercury and ytterbium into the cyclopentadienyl rings of ferrocene and cimantrene leads to chemical shift displacement of ..cap alpha..-protons of the substituted CPD ring to the weak feld, which testifies to electron-acceptor ability of these metals. The conclusion is drawn on similarity of the nature of the ytterbium- and mercury atom interaction with the cyclopentadienyl ring. The techniques are presented for the synthesis of metallocene derivatives of bivalent mercury and lanthanides in tetrahydrofuran at 20 deg C which ensure the 16% yield in preparing (C/sub 5/H/sub 5/FeC/sub 5/H/sub 4/)L2 YbxC/sub 4/H/sub 8/O and the 78% yield in preparing ((OC)/sub 3/MnC/sub 5/H/sub 4/)/sub 2/ YbxC/sub 4/H/sub 8/O.

  4. Comonomer-induced stereo-selectivity enhancement in a c2 -symmetric metallocene-catalyzed propylene polymerization.

    Science.gov (United States)

    Ma, Lin; Dong, Jin-Yong

    2015-04-01

    Propylene polymerization is carried out with a C 2 -symmetric metallocene catalyst of rac-Et(Ind)2 ZrCl2 /MAO at 40 °C in the presence of a cyclo-triene of trans,trans,cis-1,5,9-cyclododecatriene ((E,E,Z)-CDT). Comonomer incorporations are rather low (7% in [mmmm]). (E,E,Z)-CDT is speculated to coordinate to the metal center forming comonomer-complexed active sites in charge of the entire polymerization reaction with decreased activity however increased propylene -enantiomorphic selectivity. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Theoretical study on the initial reaction mechanisms of ansa-metallocene zirconium precursor on hydroxylated Si(1 0 0) surface.

    Science.gov (United States)

    Zhou, Guangfen; Ren, Jie; Zhang, Shaowen

    2016-05-01

    The initial reaction mechanisms for depositing ZrO2 thin films using ansa-metallocene zirconium (Cp2CMe2)ZrMe2 precursor were studied by density functional theory (DFT) calculations. The (Cp2CMe2)ZrMe2 precursor could be absorbed on the hydroxylated Si(1 0 0) surface via physisorption. Possible reaction pathways of (Cp2CMe2)ZrMe2 were proposed. For each reaction, the activation energies and reaction energies were compared, and stationary points along the reaction pathways were shown. In addition, the influence of dispersion effects on the reactions was evaluated by non-local dispersion corrected DFT calculations.

  6. A unique drug distribution process for radium Ra 223 dichloride injection and its implication for product quality, patient privacy, and delineation of professional responsibilities.

    Science.gov (United States)

    Dansereau, Raymond N

    2014-11-01

    On May 15, 2013, Bayer Healthcare Pharmaceuticals announced that it had received marketing approval for the therapeutic radioactive medication radium Ra 223 dichloride injection (Xofigo; Ra 223). The product acquisition and distribution process for hospital-based nuclear pharmacies and nuclear medicine services is unlike any other. The product is distributed as a low-risk compounded sterile preparation through a single compounding nuclear pharmacy located in Denver, Colorado, pursuant to a prescription. This model for drug distribution and delivery to the user institution has implications for product quality, patient privacy, and delineation of professional responsibilities. © The Author(s) 2014.

  7. Crystallization analysis fractionation of poly(ethylene-co-styrene) produced by metallocene catalysts

    KAUST Repository

    Kamal, Muhammad Shahzad

    2013-06-06

    Ethylene homo polymer and ethylene-styrene copolymers were synthesized using Cp2ZrCl2 (1)/methyl aluminoxane (MAO) and rac-silylene-bis (indenyl) zirconium dichloride (2)/MAO catalyst systems by varying styrene concentration and reaction conditions. Crystallization analysis fractionation (CRYSTAF), DSC, FTIR and 1H NMR spectroscopy were used for characterizing the synthesized polymers. Interestingly, styrene was able to increase the activity of 1/MAO and 2/MAO catalyst systems at low concentrations, but at higher concentrations the activity decreases. The 1/MAO system at low and high pressure was unable to incorporate styrene, and the final product was pure polyethylene. On the other hand, with 2/MAO polymerization of ethylene and styrene yielded copolymer containing both styrene and ethylene. Results obtained from CRYSTAF and DSC reveal that on using 1/MAO system at high pressure, the resulting polymer in the presence of styrene has similar crystallinity as the polymer produced without styrene. Using both 1/MAO at low pressure and 2/MAO leads to decrease in crystallinity with increase in styrene concentration, even though the former does not incorporate styrene. © 2013 Springer-Verlag Berlin Heidelberg.

  8. Influence of zirconocene based catalyst structure on stereo-regularity and properties of the obtained polypropylene

    International Nuclear Information System (INIS)

    Meneghetti, Mario R.; Dupont, Jairton; Forte, Madalena C.

    1997-01-01

    Metallocenes with different symmetries in combination with methylaluminoxane (MAO), have been investigated at different propylene polymerization temperatures. The metallocenes rac-ethylene bis(η 5 -1 indenyl) zirconium dichloride, with C, symmetry and isopropylidene (η 5 -cyclopentadienyl) (η 5 -9-fluorenyl) zirconium dichloride, with Cs symmetry, produce isotatic and syndiotactic polyproylene respectively. The degree of tacticity of these polymers decreases with the increase of polymerization temperature. Only atactic polypropylene was formed with the unbridged zirconocenes bis(η 5 -cyclopentadienyl) zirconium dichloride and bis (η 5 -indenyl) zirconium dichloride at any temperature investigated. The polymer microtacticity was analysed by 13 CNMR. (author)

  9. Synthesis and characterization of long chain branched isotactic polypropylene via a metallocene catalyst and T-reagent

    Science.gov (United States)

    Langston, Justin August

    Long chain branched isotactic polypropylene (LCBPP) was synthesized via the combination of a metallocene catalyst, p-(3-butenyl)styrene (T-reagent), and hydrogen. T-reagent, in the presence of hydrogen, simultaneously served as comonomer and chain transfer agent, resulting in a high molecular weight, branched polypropylene. The preparation of LCBPP by the addition of T-reagent was a one-step procedure in which the metallocene catalyst remained highly reactive. To understand the structure-property relationships, a series of LCBPP was prepared with similar weight-average molecular weights of about 250,000 g/mol and branch densities ranging from 0 (linear iPP) to 3.3 branches per 10,000 carbon. SEC equipped with triple detectors revealed the presence of high molecular weight branches whose density depended on the concentration of Treagent, hydrogen, and propylene. Melt properties were examined by small amplitude oscillatory shear and extensional flow measurements. The zero-shear viscosities of LCBPP displayed a systematic increase as branch density increased despite similar molecular weights. Strain hardening was observed in extensional flow of LCBPP. Because of these melt properties, the LCBPP and other branched polypropylenes displayed the ability to retain orientation after high temperature (T > Tm) deformations.

  10. A metallocene molecular complex as visible-light absorber for high-voltage organic-inorganic hybrid photovoltaic cells.

    Science.gov (United States)

    Ishii, Ayumi; Miyasaka, Tsutomu

    2014-04-14

    A thin solid-state dye-sensitized photovoltaic cell is fabricated by composing organic and inorganic heterojunctions in which the visible-light sensitizers are cyclopentadiene derivatives (Cp*) coordinated to a metal oxide, typically TiO2. The coordination bonds of the metallocene molecular complex (Ti-Cp*) create a new LMCT (ligand-to-metal charge transfer) absorption band and induce a rectified charge transfer from the organic ligands to TiO2, leading to photocurrent generation. Photovoltaic junctions are completed by coating crystalline organic molecules (perylene) as a hole-transport layer on the Cp*-coordinated TiO2 surface by using the vapor deposition method. The molecular plane of Cp* on the TiO2 surfaces seems to help the hole-transport layer to form ordered structures, which effectively improve carrier conductivities and minimize interfacial resistance. The organic-inorganic hybrid thin-film photocell with metallocene molecular complexes is capable of generating high open-circuit voltages exceeding 1.2 V. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Conversion of Aryl Iodides into Aryliodine(III Dichlorides by an Oxidative Halogenation Strategy Using 30% Aqueous Hydrogen Peroxide in Fluorinated Alcohol

    Directory of Open Access Journals (Sweden)

    Ajda Podgoršek

    2010-04-01

    Full Text Available Oxidative chlorination with HCl/H2O2 in 1,1,1-trifluoroethanol was used to transform aryl iodides into aryliodine(III dihalides. In this instance 1,1,1-trifluoroethanol is not only the reaction medium, but is also an activator of hydrogen peroxide for the oxidation of hydrochloric acid to molecular chlorine. Aryliodine(III dichlorides were formed in 72–91% isolated yields in the reaction of aryl iodides with 30% aqueous hydrogen peroxide and hydrochloric acid at ambient temperature. A study of the effect that substituents on the aromatic ring have on the formation and stability of aryliodine(III dichlorides shows that the transformation is easier to achieve in the presence of the electron-donating groups (i.e. methoxy, but in this case the products rapidly decompose under the reported reaction conditions to form chlorinated arenes. The results suggest that oxidation of hydrogen chloride with hydrogen peroxide is the initial reaction step, while direct oxidation of aryl iodide with hydrogen peroxide is less likely to occur.

  12. Binuclear half-metallocene chromium(III) complexes mediated ethylene polymerization with alkylaluminium as cocatalyst.

    Science.gov (United States)

    Xu, Tieqi; Pan, Yu; Lu, Xiao-Bing

    2011-09-14

    Binuclear half-metallocene chromium complexes {Cp*[3-(CH==NR)-2-O-C(10)H(5)]CrCl}(2) [Cp* = C(5)Me(5); R = (i)Pr (1), Ph (2), 2,6-(i)Pr(2)C(6)H(3) (3)] based on 1,1'-binaphthyl ligands, as well as their mononuclear analogues Cp*[3-(CH==NR)-2'-R'-2-O-C(20)H(11)]CrCl [R = (i)Pr, R' = (n)BuO (4), R = Ph, R' = (n)BuO (5), R = 2,6-(i)Pr(2)C(6)H(3), R' = (n)BuO (6), R = (i)Pr, R' = H (7)], were synthesized and characterized by mass spectrometry, elemental analysis, magnetic measurement, and UV-vis spectroscopy. The molecular structures of complexes 1, 3, 5 and 6 were further confirmed by single-crystal X-ray crystallographic analysis. When activated with a small amount of AlMe(3), these binuclear complexes exhibited higher activities in catalyzing ethylene polymerization in comparison with their mononuclear analogues, affording high molecular weight polymers with unimodal molecular weight distributions. The highest activity up to 2.87 × 10(6) g PE (mol Cr)(-1) h(-1) was achieved in the catalyst system of complex 3 bearing a bulky 2,6-(i)Pr(2)C(6)H(3) group on the imine nitrogen atom in the presence of 25 equiv. AlMe(3) as activator at 20 °C. (13)C NMR analysis indicates the resultant polymers are linear and no evidence on branch was found. This journal is © The Royal Society of Chemistry 2011

  13. Synthesis and characterization of multiferrocenyl-substituted group 4 metallocene complexes.

    Science.gov (United States)

    Kaleta, Katharina; Strehler, Frank; Hildebrandt, Alexander; Beweries, Torsten; Arndt, Perdita; Rüffer, Tobias; Spannenberg, Anke; Lang, Heinrich; Rosenthal, Uwe

    2012-10-01

    The reaction of different metallocene fragments [Cp(2)M] (Cp=η(5)-cyclopentadienyl, M=Ti, Zr) with diferrocenylacetylene and 1,4-diferrocenylbuta-1,3-diyne is described. The titanocene complexes form the highly strained three- and five-membered ring systems [Cp(2)Ti(η(2)-FcC(2)Fc)] (1) and [Cp(2)Ti(η(4)-FcC(4)Fc)](2) (Fc=[Fe(η(5)-C(5)H(4))(η(5)-C(5)H(5))]) by addition of the appropriate alkyne or diyne to Cp(2)Ti. Zirconocene precursors react with diferrocenyl- and ferrocenylphenylacetylene under C-C bond coupling to yield the metallacyclopentadienes [Cp(2)Zr(C(4)Fc(4))](3) and [Cp(2)Zr(C(4)Fc(2)Ph(2))](5), respectively. The exchange of the zirconocene unit in 3 by hydrogen atoms opens the route to the super-crowded ferrocenyl-substituted compound tetraferrocenylbutadiene (4). On the other hand, the reaction of 1,4-diferrocenylbuta-1,3-diyne with zirconocene complexes afforded a cleavage of the central C-C bond, and thus, dinuclear [{Cp(2)Zr(μ-η(1):η(2)-C≡CFc)}(2)] (6) that consists of two zirconocene acetylide groups was formed. Most of the complexes were characterized by single-crystal X-ray crystallography, showing attractive multinuclear molecules. The redox properties of 3, 5, and 6 were studied by cyclic voltammetry. Upon oxidation to 3(n+), 5(n+), and 6(n+) (n=1-3), decomposition occured with in situ formation of new species. The follow-up products from 3 and 5 possess two or four reversible redox events pointing to butadiene-based molecules. However, the dinuclear complex 6 afforded ethynylferrocene under the measurement conditions. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Crystalline structure changes in preoriented metallocene-based isotactic polypropylene upon annealing.

    Science.gov (United States)

    Wang, Yan; Xu, Jia-Zhuang; Chen, Yan-Hui; Qiao, Kai; Xu, Ling; Ji, Xu; Li, Zhong-Ming; Hsiao, Benjamin S

    2013-06-13

    Partially melted metallocene-based isotactic polypropylene (m-iPP), which was preoriented with a high degree of molecular orientation and a shish-kebab structure, was annealed at various temperatures and isothermally crystallized at 130 °C. The melting and crystallization process was examined using synchrotron wide-angle X-ray diffraction, small-angle X-ray scattering, and differential scanning calorimetry. For the m-iPP samples annealed at relatively low temperatures, lamellar thickening, lateral growth, and a decrease in the γ-crystal fraction occurred. Because of parallel evolution of α- and γ-crystal growth in the limited crystallizable melt volume, the fraction of γ-crystals was very low. Furthermore, topological constraints in the melt dominate the chain flux in crystal evolution; the chains are consumed by the thickening lamellae and lateral growth, forming α-crystals with parallel chains in the unit cell. For the m-iPP samples isothermally annealed at medium annealing temperatures, the increase in the amount of crystallizable melt caused the γ-crystal fraction to increase. A shish-kebab (α-crystals) structure with high thermal stability and a newly formed macro-unoriented structure coexisted in the final sample. After annealing at high temperatures, at which no crystals survived, γ-crystal formation was greatly favored; this was attributed to the nature of m-iPP molecules and their dynamic behavior at 130 °C. Because of the lack of oriented nuclei, randomly oriented lamellae were formed. On the basis of the structural cooperative changes at different scales, the morphological features at different annealing temperatures were proposed.

  15. Infrared spectrum and structure of the homochiral serine octamer-dichloride complex

    Science.gov (United States)

    Seo, Jongcheol; Warnke, Stephan; Pagel, Kevin; Bowers, Michael T.; von Helden, Gert

    2017-12-01

    The amino acid serine is known to form a very stable octamer that has properties that set it apart from serine complexes of different sizes or from complexes composed of other amino acids. For example, both singly protonated serine octamers and anionic octamers complexed with two halogen ions strongly prefer homochirality, even when assembled from racemic D,L mixtures. Consequently, the structures of these complexes are of great interest, but no acceptable candidates have so far been identified. Here, we investigate anionic serine octamers coordinated with two chloride ions using a novel technique coupling ion mobility spectrometry-mass spectrometry with infrared spectroscopy, in combination with theoretical calculations. The results allow the identification of a unique structure for (Ser8Cl2)2- that is highly symmetric, very stable and homochiral and whose calculated properties match those observed in experiments.

  16. Si-H bond activation of alkynylsilanes by group 4 metallocene complexes.

    Science.gov (United States)

    Lamac, Martin; Spannenberg, Anke; Baumann, Wolfgang; Jiao, Haijun; Fischer, Christine; Hansen, Sven; Arndt, Perdita; Rosenthal, Uwe

    2010-03-31

    The reactivity of variously substituted alkynylsilanes toward selected group 4 metallocene complexes was investigated. Reactions of the alkynylsilanes R(1)C(2)SiR(2)(2)H (R(1) = SiMe(3), R(2) = Me, 1; R(1) = SiMe(3), R(2) = Ph, 2; R(1) = SiMe(2)H, R(2) = Me, 5) with Cp(2)TiMe(2) (Cp = eta(5)-cyclopentadienyl) resulted, upon methyl group transfer to the silyl group, in the previously described titanocene alkyne complexes Cp(2)Ti(R(1)C(2)SiR(2)(2)R(3)) (R(1) = Me(3)Si, R(2) = R(3) = Me, 3; R(1) = HMe(2)Si, R(2) = R(3) = Me, 6) or the unreported complex 4 (R(1) = Me(3)Si, R(2) = Ph, R(3) = Me). The Cp(2)TiCl(2)/n-BuLi system yielded alkyne complexes 6 and 7 (R(1) = HMe(2)Si, R(2) = Me, R(3) = H); no alkyl group transfer was detected. On the other hand, reactions utilizing the Cp(2)ZrCl(2)/n-BuLi system afforded inseparable mixtures; however, complexes of the type Cp(2)Zr[R(1)C(2)SiMe(2)(n-Bu)] (R(1) = Me(3)Si, 8; R(1) = HMe(2)Si, 9) were detected. Cp(2)Hf(n-Bu)(2) reacted with the alkynylsilanes in a diverse way, depending on the substituents of the alkyne substrate. The reaction with an excess of alkyne 1 (R(1) = Me(3)Si, R(2) = Me) afforded only an intractable mixture, which contained Me(3)SiC(2)SiMe(2)(n-Bu) (10). Hafnacyclopentadienes 13-15 as precedented product types were obtained when alkyne 12 (R(1) = Ph, R(2) = Me) was used. In sharp contrast, the symmetrically substituted alkynes 5 (R(1) = HMe(2)Si, R(2) = Me) and H(2)PhSiC(2)SiPhH(2) (18) yielded the hitherto unknown Si-containing metallacycles 16 and 19. A reaction mechanism leading to these products was proposed and subsequently supported by DFT calculations. In addition, the reduction of Cp(2)HfCl(2) with magnesium in THF in the presence of alkynylsilanes was shown to be an alternative route to compounds 14-16 and 19. Presumably due to steric reasons, alkyne 1 could not form any of the product types described above. Nevertheless, it was utilized for the preparation of the PMe(3)-stabilized hafnocene

  17. Creation of metal-containing carbon onions via self-assembly in metallocene/benzene solution irradiated with an ultraviolet laser

    International Nuclear Information System (INIS)

    Hayasaki, Yasuhiro; Maekawa, Toru; Fukuda, Takahiro; Hasumura, Takashi

    2012-01-01

    We irradiate sub- and super-critical benzene, in which metallocene such as ferrocene or cobaltocene is dissolved, with a UV laser of 266 nm wavelength, and show that benzene and metallocenes are dissociated and iron- and cobalt-containing carbon onions (Fe-C and Co-C) are created. The operational temperature of the present method is much lower than that of conventional ones for the growth of nanomaterials and therefore coagulation among metal-containing carbon onions is avoided. The average diameters of the core iron and cobalt nanoparticles are, respectively, 7.5 and 7.2 nm, whereas the thickness of the layers of carbon onions surrounding the core metal particles is 3.2 nm in both Fe-C and Co-C cases. The metal-containing carbon onions show superparamagnetic characteristics. (paper)

  18. Creation of metal-containing carbon onions via self-assembly in metallocene/benzene solution irradiated with an ultraviolet laser

    Science.gov (United States)

    Hayasaki, Yasuhiro; Fukuda, Takahiro; Hasumura, Takashi; Maekawa, Toru

    2012-09-01

    We irradiate sub- and super-critical benzene, in which metallocene such as ferrocene or cobaltocene is dissolved, with a UV laser of 266 nm wavelength, and show that benzene and metallocenes are dissociated and iron- and cobalt-containing carbon onions (Fe@C and Co@C) are created. The operational temperature of the present method is much lower than that of conventional ones for the growth of nanomaterials and therefore coagulation among metal-containing carbon onions is avoided. The average diameters of the core iron and cobalt nanoparticles are, respectively, 7.5 and 7.2 nm, whereas the thickness of the layers of carbon onions surrounding the core metal particles is 3.2 nm in both Fe@C and Co@C cases. The metal-containing carbon onions show superparamagnetic characteristics.

  19. Recent studies on appearance energy and hot reaction zone in solid-state reactions in metallocenes and their β-cyclodextrin inclusion compounds

    International Nuclear Information System (INIS)

    Yoshihara, K.; Sekine, T.; Matsue, H.

    1994-01-01

    Striking contrasts were observed in the hot atom chemical retention-recoil energy relation between metallocenes and their β-cyclodextrin inclusion compounds. Energy dependence curves of the parent yields in ferrocene and ruthenocene dramatically dropped by the inclusion. However, the curve in osmocene did not change remarkably. Surprisingly, the parent yield was represented by one curve for ferrocene, ruthenocene and osmocene with inclusion. The independence on the chemical character was explained by considering that a larger reaction zone in pure metallocene was restricted by inclusion, and a hot atom reaction occurred in a unimolecular manner in the cyclodextrin cavity which led to the independence on elemental characters. Normalized appearance energy was estimated for the diagnosis of the processes in concern. Isotope effects in hot atom chemistry in ruthenocene-ferrocene mixtures were found for (γ, n) reactions for the first time. ((orig.))

  20. The effect of doping on the energetics and quantum conductance in graphene nanoribbons with a metallocene adsorbate

    Science.gov (United States)

    Kang, Hong Seok; Pramanik, Anup

    2011-09-01

    Based on a PBE-D2 calculation that empirically includes van der Waals interactions to the standard GGA approximation of Perdew, Berke, and Ernzerhof, we have investigated the adsorption of ferrocene or ruthenocene on pristine and X-doped graphene (GrS) or graphene nanoribbons (GNRs), where X (=B or N) is a p-type or n-type heteroatom. First, we find that van der Waals interactions play a dominant role in the adsorption. Second, we find that metallocene adsorption on doped GNRs introduces different effects in the low-bias conductance, not far from the linear response regime, of GNRs depending upon the doping type. Adsorption on undoped or p-type GNRs brings about a slight reduction in conductance due to an introduction of quasi-bound states just below the Fermi level. No appreciable reduction is expected in n-type GNRs because those states are introduced far below the Fermi level.

  1. Catalisadores metalocênicos: aspectos gerais e heterogeneização Metallocene catalysts: general aspects and heterogenization

    Directory of Open Access Journals (Sweden)

    Maria de Fátima V. Marques

    1998-01-01

    Full Text Available Este trabalho apresenta uma discussão sobre aspectos gerais da nova tecnologia de síntese de polímeros com microestrutura e propriedades controladas, obtidos via sistema catalítico metaloceno/MAO. Mostra a importância da heterogeneização desses sistemas para possibilitar o seu emprego na produção industrial de uma ampla classe de materiais poliméricos. São discutidas ainda as principais características dos suportes mais empregados para esses catalisadores.This work presents a discussion about the general aspects of the new technology for the synthesis of polymers with controlled microstructure and properties, obtained by metallocene/MAO catalyst system. It shows the relevance of heterogenization of these systems to allow their application for industrial production of a large range of polymer materials. The characteristics of the more used supports for these catalysts are also discussed.

  2. Effect of Mn doped-titania on the activity of metallocene catalyst by in situ ethylene polymerization

    KAUST Repository

    Abdul Kaleel, S. H.

    2012-09-01

    Ethylene polymerization was carried out using highly active metallocene catalysts (Cp 2ZrCl 2 and Cp 2TiCl 2) in combination with methylalumoxane. Titanium(IV) oxide containing 1% Mn as dopant was used as nanofillers. The influence of filler concentration, reaction temperature and pressure on the catalytic activity and polymer properties was investigated. There was a fourfold increase in the activity of zirconocene catalyst by addition of doped-titania. The morphology indicates that the doped-titania nanoparticles have a nucleus effect on the polymerization and caused a homogeneous PE shell around them. The optimum condition for polymerization was found to be 30°C. © 2012 The Korean Society of Industrial and Engineering Chemistry.

  3. Carbon monoxide and related π-acceptors are good ligands for trivalent metallocenes of uranium and the trans-uranium metals

    International Nuclear Information System (INIS)

    Andersen, R.A.

    1990-01-01

    The evolution of the concept that tertiary phosphines are good ligands towards the tetravalent uranium halides and that phosphines, carbon monoxide, and related π-acceptor ligands are good ligands towards the trivalent uranium metallocenes will be described. Solid state X-ray, crystallographic and solution state equilibrium quotient studies show the ligand displacement series: (RO) 3 P > R 3 P > R 3 N; RNC > RCN. These concepts will be extended to the trans-uranium element neptunium and plutonium

  4. Metal-cyclopentadienyl bond energies in metallocene cations measured using threshold collision-induced dissociation mass spectrometry.

    Science.gov (United States)

    Rowland, Tyson G; Sztáray, Bálint; Armentrout, Peter B

    2013-02-14

    Metal-cyclopentadienyl bond dissociation energies (BDEs) were measured for seven metallocene ions (Cp(2)M(+), Cp = η(5)-cyclopentadienyl = c-C(5)H(5), M = Ti, V, Cr, Mn, Fe, Co, Ni) using threshold collision-induced dissociation (TCID) performed in a guided ion beam tandem mass spectrometer. For all seven room temperature metallocene ions, the dominant dissociation pathway is simple Cp loss from the metal. Traces of other fragment ions were also detected, such as C(10)H(10)(+), C(10)H(8)(+), C(8)H(8)(+), C(3)H(3)(+), H(2)M(+), C(3)H(3)M(+), C(6)H(6)M(+), and C(7)H(6)M(+), depending on the metal center. Statistical modeling of the Cp-loss TCID experimental data, including consideration of energy distributions, multiple collisions, and kinetic shifts, allow the extraction of 0 K [CpM(+)- Cp] BDEs. These are found to be 4.85 ± 0.15, 4.02 ± 0.14, 4.22 ± 0.13, 3.51 ± 0.12, 4.26 ± 0.15, 4.57 ± 0.15, and 3.37 ± 0.12 eV for Cp(2)Ti(+), Cp(2)V(+), Cp(2)Cr(+), Cp(2)Mn(+), Cp(2)Fe(+), Cp(2)Co(+), and Cp(2)Ni(+), respectively. The measured BDE trend is largely in line with arguments based on a simple molecular orbital picture, with the exception of the anomalous case of titanocene, most likely attributable to its bent structure. The new results presented here are compared to previous literature values and are found to provide a more complete and accurate set of thermochemistry.

  5. Effects of supported metallocene catalyst active center multiplicity on antioxidant-stabilized ethylene homo- and copolymers

    KAUST Repository

    Atiqullah, Muhammad

    2014-10-09

    © 2014 Akadémiai Kiadó, Budapest, Hungary. A silica-supported bis(n-butylcyclopentadienyl) zirconium dichloride [( n BuCp)2ZrCl2] catalyst was synthesized. This was used to prepare an ethylene homopolymer and an ethylene-1-hexene copolymer. The active center multiplicity of this catalyst was modeled by deconvoluting the copolymer molecular mass distribution and chemical composition distribution. Five different active site types were predicted, which matched the successive self-nucleation and annealing temperature peaks. The thermo-oxidative melt stability, with and without Irganox 1010 and Irgafos 168, of the above polyethylenes was investigated using nonisothermal differential scanning calorimetric (DSC) experiments at 150 °C. This is a temperature that ensures complete melting of the samples and avoids the diffusivity of oxygen to interfere into polyethylene crystallinity and its thermo-oxidative melt degradation. The oxidation parameters such as onset oxidation temperature, induction period, protection factor, and S-factor were determined by combining theoretical modeling with the DSC experiments. Subsequently, these findings were discussed considering catalyst active center multiplicity and polymer microstructure, particularly average ethylene sequence length. Several insightful results, which have not been reported earlier in the literature, were obtained. The antioxidant effect, for each polymer, varied as (Irganox + Irgafos) ≈ Irganox > Irgafos > Neat polymer. The as-synthesized homopolymer turned out to be almost twice as stable as the corresponding copolymer. The antioxidant(s) in the copolymer showed higher antioxidant effectiveness (AEX) than those in the homopolymer. Irganox exhibited more AEX than Irgafos. To the best of our knowledge, such findings have not been reported earlier in the literature. However, mixed with Irganox or Irgafos, their melt oxidation stability was comparable. The homopolymer, as per the calculated S-factor, showed Irganox

  6. The role of defect microstructure in the crystallization behavior of metallocene and MgCl2-supported Ziegler-Natta isotactic poly(propylenes

    Directory of Open Access Journals (Sweden)

    Rufina G. Alamo

    2003-12-01

    Full Text Available The intermolecular defect distribution of poly(propylenes of the Ziegler-Natta (ZN and metallocene (M types is assessed by classical fractionation and analysis of the fractions by GPC and 13C NMR. In addition, the linear growth rates, a property sensitive to differences in defects distribution in the poly(propylene chain, are used to infer the stereoblock-like intramolecular distribution of defects in industrial type ZN iPPs and their fractions. The behavior of fractions from a matched metallocene iPP provide direct evidence of the single-site nature of the catalyst. Metallocene poly(propylenes enable a quantitative assessment of the molecular, thermodynamic and kinetic factors that govern the formation and concentrations of the a and g polymorphs. Short continuous crystallizable sequences and high crystallization temperatures favor the formation of this polymorph in homo poly(propylenes and random propylene copolymers. Differences in the partitioning of the comonomer between the crystalline and non-crystalline regions leads to contents of the gamma phase that differ among the copolymers at any given crystallization temperature. Qualitatively these differences can be used to assess the degree to which a counit participates in the crystallite.

  7. Low temperature in situ synthesis and the formation mechanism of various carbon-encapsulated nanocrystals by the electrophilic oxidation of metallocene complexes

    Science.gov (United States)

    Liu, Boyang; Fan, Chunhua; Chen, Jianwei; Wang, Junhua; Lu, Zepeng; Ren, Jiayuan; Yu, Shuaiqin; Dong, Lihua; Li, Wenge

    2016-02-01

    The core-shell nanostructures have the advantages of combining distinctive properties of varied materials and improved properties over their single-component counterparts. Synthesis approaches for this class of nanostructures have been intensively explored, generally involving multiple steps. Here, a general and convenient strategy is developed for one-step in situ synthesis of various carbon-encapsulated nanocrystals with a core-shell structure via a solid-state reaction of metallocene complexes with (NH4)2S2O8 in an autoclave at 200 °C. A variety of near-spherical and equiaxed nanocrystals with a small median size ranging from 6.5 to 50.6 nm are prepared as inner cores, including Fe7S8, Ni3S4 and NiS, CoS, TiO2, TiO2 and S8, ZrO2, (NH4)3V(SO4)3 and VO2, Fe7S8 and Fe3O4, MoS2 and MoO2. The worm-like carbon shell provides exclusive room for hundreds of nanocrystals separated from each other, preventing nanocrystal aggregation. The synergistic effect of ammonium and a strong oxidizing anion on the electrophilic oxidation of metallocene complexes containing a metal-ligand π bond contributes to the carbon formation at low temperature. It is considered that the cyclopentadienyl ligand in a metallocene complex will decompose into highly reactive straight chain olefinic pieces and the metal-olefin π interaction enables an ordered self-assembly of olefinic pieces on nanocrystals to partially form graphitizable carbon and a core-shell structure. The high capacity, good cycling behavior and rate capability of Fe7S8@C and Ni3S4 and NiS@C electrodes are attributed to the good protection and electrical conductivity of the carbon shell.

  8. Low temperature in situ synthesis and the formation mechanism of various carbon-encapsulated nanocrystals by the electrophilic oxidation of metallocene complexes

    International Nuclear Information System (INIS)

    Liu, Boyang; Fan, Chunhua; Chen, Jianwei; Wang, Junhua; Lu, Zepeng; Ren, Jiayuan; Yu, Shuaiqin; Dong, Lihua; Li, Wenge

    2016-01-01

    The core–shell nanostructures have the advantages of combining distinctive properties of varied materials and improved properties over their single-component counterparts. Synthesis approaches for this class of nanostructures have been intensively explored, generally involving multiple steps. Here, a general and convenient strategy is developed for one-step in situ synthesis of various carbon-encapsulated nanocrystals with a core–shell structure via a solid-state reaction of metallocene complexes with (NH 4 ) 2 S 2 O 8 in an autoclave at 200 °C. A variety of near-spherical and equiaxed nanocrystals with a small median size ranging from 6.5 to 50.6 nm are prepared as inner cores, including Fe 7 S 8 , Ni 3 S 4 and NiS, CoS, TiO 2 , TiO 2 and S 8 , ZrO 2 , (NH 4 ) 3 V(SO 4 ) 3 and VO 2 , Fe 7 S 8 and Fe 3 O 4 , MoS 2 and MoO 2 . The worm-like carbon shell provides exclusive room for hundreds of nanocrystals separated from each other, preventing nanocrystal aggregation. The synergistic effect of ammonium and a strong oxidizing anion on the electrophilic oxidation of metallocene complexes containing a metal–ligand π bond contributes to the carbon formation at low temperature. It is considered that the cyclopentadienyl ligand in a metallocene complex will decompose into highly reactive straight chain olefinic pieces and the metal–olefin π interaction enables an ordered self-assembly of olefinic pieces on nanocrystals to partially form graphitizable carbon and a core–shell structure. The high capacity, good cycling behavior and rate capability of Fe 7 S 8 @C and Ni 3 S 4 and NiS@C electrodes are attributed to the good protection and electrical conductivity of the carbon shell. (paper)

  9. Synthesis, growth and characterization of L-lysinium(+)...L-lysinium(2+) dichloride perchlorate (LLDP) single crystals by Sankaranarayanan-Ramasamy method.

    Science.gov (United States)

    Vasudevan, V; Ramesh Babu, R; Ramamurthi, K

    2012-12-01

    L-lysinium(+)...L-lysinium(2+) dichloride perchlorate was synthesized at ambient temperature and bulk single crystals were grown by conventional and Sankaranarayanan-Ramasamy methods. Crystals grown by these methods were subjected to single crystal X-ray diffraction, Fourier transform infrared, high resolution X-ray diffraction, Vickers microhardness and thermogravimetric/differential scanning calorimetric/differential thermal analyses. Further, the cut-off wavelength and optical transmittance of the grown crystals were determined by UV-vis-NIR spectrum. Linear refractive index (n(x)) of the crystal was measured using minimum deviation method for different wavelengths. Optical quality of the grown crystals was analyzed by conoscopic interference pattern and the birefringence was calculated using interferometric technique. Surface laser damage threshold of the crystal was determined using Nd:YAG laser. The nonlinear refractive index n(2) was measured through the Z-scan technique using low power continuous wave HeNe laser. Frequency and temperature dependent dielectric constant (ε(r)) and dielectric loss (tanδ) were measured. Copyright © 2012 Elsevier B.V. All rights reserved.

  10. Synthesis, growth and characterization of L-lysinium(+)…L-lysinium(2+) dichloride perchlorate (LLDP) single crystals by Sankaranarayanan-Ramasamy method

    Science.gov (United States)

    Vasudevan, V.; Ramesh Babu, R.; Ramamurthi, K.

    2012-12-01

    L-lysinium(+)…L-lysinium(2+) dichloride perchlorate was synthesized at ambient temperature and bulk single crystals were grown by conventional and Sankaranarayanan-Ramasamy methods. Crystals grown by these methods were subjected to single crystal X-ray diffraction, Fourier transform infrared, high resolution X-ray diffraction, Vickers microhardness and thermogravimetric/differential scanning calorimetric/differential thermal analyses. Further, the cut-off wavelength and optical transmittance of the grown crystals were determined by UV-vis-NIR spectrum. Linear refractive index (nx) of the crystal was measured using minimum deviation method for different wavelengths. Optical quality of the grown crystals was analyzed by conoscopic interference pattern and the birefringence was calculated using interferometric technique. Surface laser damage threshold of the crystal was determined using Nd:YAG laser. The nonlinear refractive index n2 was measured through the Z-scan technique using low power continuous wave Hesbnd Ne laser. Frequency and temperature dependent dielectric constant (ɛr) and dielectric loss (tan δ) were measured.

  11. Synthesis and Mössbauer spectroscopy of formal tin(II) dichloride and dihydride species supported by Lewis acids and bases.

    Science.gov (United States)

    Al-Rafia, S M Ibrahim; Shynkaruk, Olena; McDonald, Sean M; Liew, Sean K; Ferguson, Michael J; McDonald, Robert; Herber, Rolfe H; Rivard, Eric

    2013-05-06

    (119)Sn Mössbauer spectroscopy was performed on a series of formal Sn(II) dichloride and dihydride adducts bound by either carbon- or phosphorus-based electron pair donors. Upon binding electron-withdrawing metal pentacarbonyl units to the tin centers in LB·SnCl2·M(CO)5 (LB = Lewis base; M = Cr or W), a significant decrease in isomer shift (IS) was noted relative to the unbound Sn(II) complexes, LB·SnCl2, consistent with removal of nonbonding s-electron density from tin upon forming Sn-M linkages (M = Cr and W). Interestingly, when the nature of the Lewis base in the series LB·SnCl2·W(CO)5 was altered, very little change in the IS values was noted, implying that the LB-Sn bonds were constructed with tin-based orbitals of large p-character (as supported by prior theoretical studies). In addition, variable temperature Mössbauer measurements were used to determine the mean displacement of the tin atoms in the solid state, a parameter that can be correlated with the degree of covalent bonding involving tin in these species.

  12. Polypropylene Nano composites Obtained by In Situ Polymerization Using Metallocenes Catalyst: Influence of the Nanoparticles on the Final Polymer Morphology

    International Nuclear Information System (INIS)

    Zapata, P.; Quijada, R.

    2012-01-01

    Polypropylene nano composites containing silica nanospheres based on the sol-gel methods were produced via in situ polymerization using a rac-Et(Ind) 2 ZrCl 2 /methylaluminoxane (MAO) system. Two different routes were used depending on the interaction between the silica nanoparticles with the catalytic system. In route 1 the nanoparticles were added together with the catalytic system (rac-Et(Ind) 2 ZrCl 2 )/(MAO) directly into the reactor, and in route 2 the metallocenes rac-Et(Ind) 2 ZrCl 2 was supported on silica nanospheres pretreated with (MAO). SEM images show that when the nanospheres were added by both routes, they were replicated in the final polymer particle morphology; this phenomenon was more pronounced for PP obtained by route 2. The polypropylene (PP) nano composites obtained by both routes had a slightly higher percent crystallinity and crystallinity temperatures than pure PP. Transmission electron microscopy (TEM) images show that the nanospheres were well dispersed into the polypropylene matrix, particularly in the nano composites obtained by the support system (route 2).

  13. Suppressing of γ-crystal formation in metallocene-based isotactic polypropylene during isothermal crystallization under shear flow.

    Science.gov (United States)

    Wang, Yan; Chen, Chen; Xu, Jia-Zhuang; Lei, Jun; Mao, Yimin; Li, Zhong-Ming; Hsiao, Benjamin S

    2012-04-26

    The effect of shear flow on isothermal crystallization behavior of γ-crystals in metallocene-based isotactic polypropylene melt was investigated by in situ synchrotron wide-angle X-ray diffraction (WAXD). In the sample under weak shear (at strain of 300% for 30 s duration), simultaneous evolution of α- and γ-crystals occurred, and the final fraction of γ-crystals (fγ) was 0.66, which was identical to the undeformed sample (PP-Static). In this scenario, α-crystals probably served as effective seeds for nucleation of γ-crystals. In the samples under strong shear (at strain of 500% for 30 s duration or long-time continuous shear at strains of 100% and 500%), the sequential emergence of α- and γ-crystals was observed. In this case, molten polymer chains were probably constrained by the surrounding crystals after intense short-time shear and/or maintained their extended chain conformation after long-time shear. These oriented chains had little chance to form the γ-crystals directly, behaving very differently from the relaxed chains. Under strong shear fields, the emergence of γ-crystals was delayed or inhibited, whereas the fγ value was also decreased rapidly. A simple model for the possible pathway of γ-crystal formation in the strong shear environment was proposed.

  14. Effect of DBPH and vacuum gamma radiation on metallocenic ethylene-1-hexene and ethylene-1-octadecene copolymers

    International Nuclear Information System (INIS)

    Satti, A.J.; Andreucetti, N.A.; Quijada, R.; Sarmoria, C.; Valles, E.M.

    2010-01-01

    Two different post reactor processes were compared, 60 Co vacuum gamma irradiation and chemical modification with 2,5-dimethyl-2,5-di(tert-butylperoxy)-hexane (DBPH), on two metallocenic copolymers. These copolymers have a similar molecular weight and crystallinity, but different side chain lengths and concentration of end vinyl groups. The influence of the crosslinking agents on the structure of the samples was studied using gel extraction, size exclusion chromatography (SEC), FTIR spectroscopy and differential scanning calorimetry (DSC). The analysis of the data indicates that crosslinking reactions predominated over scission reactions in all cases. At the same conversion, peroxide modified samples show higher crosslinking levels than irradiated samples. The modified polymers show a complex rheological behavior and an increment in their rheological properties due to crosslinking. FTIR data demonstrated a depletion of vinyl terminal groups with the increment of the absorbed dose and the peroxide concentrations applied. This depletion was more significant in the peroxide crosslinked samples. A mathematical model that accounts for scission and crosslinking reactions fitted well the experimental data.

  15. Reduction of dinitrogen with an yttrium metallocene hydride precursor, [(C5Me5)2YH]2.

    Science.gov (United States)

    Schmiege, Benjamin M; Ziller, Joseph W; Evans, William J

    2010-11-15

    Treatment of [(C(5)Me(5))(2)YH](2), 1, with KC(8) under N(2) in methylcyclohexane generates the unsolvated reduced dinitrogen complex, [(C(5)Me(5))(2)Y](2)(μ-η(2):η(2)-N(2)), 2, and extends the range of yttrium and lanthanide LnZ(2)Z'/M (Z = monoanion; M = alkali metal) dinitrogen reduction reactions to (Z')(-) = (H)(-). The hydride complex, 1, is unique in this reactivity compared to other alkane-soluble yttrium metallocenes, [(C(5)Me(5))(2)YX](x) {X = [N(SiMe(3))(2)](-), (Me)(-), (C(3)H(5))(-), and (C(5)Me(5))(-)} which did not generate 2 when treated with KC(8). [(C(5)Me(5))(2)LnH](x)/KC(8)/N(2) reactions with Ln = La and Lu did not give isolable dinitrogen complexes. Complex 2 and the unsolvated lutetium analogue, [(C(5)Me(5))(2)Lu](2)(μ-η(2):η(2)-N(2)), 3, were obtained using benzene as a solvent and [(C(5)Me(5))(2)Ln][(μ-Ph)(2)BPh(2)] as precursors with excess KC(8). Complex 2 functions as a reducing agent with PhSSPh to form [(C(5)Me(5))(2)Y(μ-SPh)](2), 4, in high yield.

  16. Polypropylene Nanocomposites Obtained by In Situ Polymerization Using Metallocene Catalyst: Influence of the Nanoparticles on the Final Polymer Morphology

    Directory of Open Access Journals (Sweden)

    Paula Zapata

    2012-01-01

    Full Text Available Polypropylene nanocomposites containing silica nanospheres based on the sol-gel methods were produced via in situ polymerization using a rac-Et(Ind2ZrCl2/methylaluminoxane (MAO system. Two different routes were used depending on the interaction between the silica nanoparticles with the catalytic system. In route 1 the nanoparticles were added together with the catalytic system (rac-Et(Ind2ZrCl2/(MAO directly into the reactor, and in route 2 the metallocene rac-Et(Ind2ZrCl2 was supported on silica nanospheres pretreated with (MAO. SEM images show that when the nanospheres were added by both routes, they were replicated in the final polymer particle morphology; this phenomenon was more pronounced for PP obtained by route 2. The polypropylene (PP nanocomposites obtained by both routes had a slightly higher percent crystallinities and crystallinity temperatures than pure PP. Transmission electron microscopy (TEM images show that the nanospheres were well dispersed into the polypropylene matrix, particularly in the nanocomposites obtained by the support system (route 2.

  17. Cu-Containing Polymer Nanocomposites on the Basis Of Some (Co)Polymers Obtained Using Novel Non-Metallocene Type Ti-Containing Catalysts

    Science.gov (United States)

    Kalbaliyeva, Elnara; Aliyeva, Reyhan; Azizov, Akif

    Polyethylenes and ethylene/1-hexene copolymers with various thermo-dynamic and structural parameters in the presence of novel non-metallocene type Ti-containing efficient catalytic systems, and Cu-containing polymer nano-composites were prepared. Polyolefins and composites have been investigated using such methods as Differential Scanning Calorimetry, IR spectroscopy and X-ray phase analysis. It is shown that introduction of Cu-containing particles (Cu/Cu2O) having sizes lower than 10 nm, determined by EMR method, in polymer matrix allows to obtain metal-polymer composites with improved thermal properties.

  18. Paramagnetic titanium(III) and zirconium(III) metallocene complexes as precatalysts for the dehydrocoupling/dehydrogenation of amine-boranes.

    Science.gov (United States)

    Helten, Holger; Dutta, Barnali; Vance, James R; Sloan, Matthew E; Haddow, Mairi F; Sproules, Stephen; Collison, David; Whittell, George R; Lloyd-Jones, Guy C; Manners, Ian

    2013-01-02

    Complexes of Group 4 metallocenes in the +3 oxidation state and amidoborane or phosphidoborane function as efficient precatalysts for the dehydrocoupling/dehydrogenation of amine-boranes, such as Me(2) NH⋅BH(3). Such Ti(III) -amidoborane complexes are generated in [Cp(2)Ti]-catalyzed amine-borane dehydrocoupling reactions, for which diamagnetic M(II) and M(IV) species have been previously postulated as precatalysts and intermediates. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. MS characterization of some metallocene dithiolene chelate complexes of the early transition metals - first synthesis of vanadocene toluene-3,4-dithiolate

    International Nuclear Information System (INIS)

    Klapoetke, T.; Koepf, H.

    1988-01-01

    Fragmentation patterns (under the conditions in the mass spectrometer) of the metallocene dithiolene chelate complexes of some early transition metals (subgroup IV-VI) were investigated. In some cases ion geneses could be elucidated by purchasing metastable transitions, using the linked scan technique. After cleavage of one cyclopentadienyl ring the unsubstituted ethene dithiolates surprisingly show an intense peak corresponding to an elimination of acetylene as a neutral particle, which contrasts to the analogous maleonitrile derivatives. The first synthesis of Cp 2 V(1,2-S 2 C 6 H 3 CH 3 -4) (Cp = C 5 H 5 ) is described. (author)

  20. The molecular, electronic, bonding, and photophysical features of the [(c-Pt3)Tl(c-Pt3)]+ inorganic metallocenes.

    Science.gov (United States)

    Tsipis, Athanassios C; Gkekas, George N

    2013-06-21

    The molecular, electronic, bonding and photophysical properties of a series of inorganic metallocenes with the general formula {[Pt3(μ2-L)3(L')3]2(μ6-Tl)}(+) (L = CO, CH3CN, PH2, C6F5, or SO2 and L' = CO, PH3, CH3CN, C6F5) have been studied by means of DFT electronic structure calculations. The estimated Tl-cd distances between Tl(+) cations and the centroids (cd) of the trimetallic Pt3(μ2-L)3(L')3 {3 : 3 : 3} decks were found in the range 2.932-3.397 Å. The predicted bond dissociation energy, D0, of the (c-Pt3)···Tl(+) bonds was found to lie within the range -31.5 up to -77.5 kcal mol(-1) at the B3LYP/LANL2TZ(f)(Pt) ∪ 6-31G(d,p)(E) ∪ SRLC(Tl) level of theory. Most of the [(c-Pt3)Tl(c-Pt3)](+) inorganic metallocenes adopt a bend titanocene-like structure. The Localized Orbital Locator (LOL) contour maps along with the 3D contour plots of the Reduced Gradient Density (RDG) mirror the composite nature of the interaction of Tl(+) with the triangular Pt3 metallic ring cores consisting of electrostatic, covalent and dispersion interaction components. The Pt3···Tl(+)···Pt3 bonding mode was further validated by Energy Decomposition Analysis (EDA) calculations which demonstrated that the electrostatic and covalent components of the interaction contribute almost equally to the bonding interactions. Furthermore, Charge Decomposition Analysis (CDA) and Natural Bond Orbital Analysis (NBO) calculations indicated that charge transfer from the Tl(+) cation to the Pt3(0) {3 : 3 : 3} decks also occurs. The {[Pt3(μ2-L)3(L')3]2(μ6-Tl)}(+) sandwiches absorb in the UV-Vis region (300-500 nm) and emit in the visible-near IR region (600-1000 nm). The absorption bands are mainly of MLCT/MC character while phosphorescence is predicted to occur via the first triplet excited state, T1, since the spin density of this excited state could be described as a SOMO - 1/SOMO combination. Generally, no significant distortions occur upon excitation of these systems

  1. Steric and electronic effects of 1,3-disubstituted cyclopentadienyl ligands on metallocene derivatives of Cerium, Titanium, Manganese, and Iron

    Energy Technology Data Exchange (ETDEWEB)

    Sofield, Chadwick Dean [Univ. of California, Berkeley, CA (United States)

    2000-05-01

    Sterically demanding 1,3-disubstituted cyclopentadienyl ligands were used to modify the physical properties of the corresponding metallocenes. Sterically demanding ligands provided kinetic stabilization for trivalent cerium compounds. Tris(di-t-butylcyclopentadienyl)cerium was prepared and anion competition between halides and cyclopentadienyl groups which had complicated synthesis of the tris(cyclopentadienyl)compound was qualitatively examined. Bis(di-t-butylcyclopentadienyl)cerium methyl was prepared and its rate of decomposition, by ligand redistribution, to tris(di-t-butylcyclopentadienyl)cerium was shown to be slower than the corresponding rate for less sterically demanding ligands. Asymmetrically substituted ligands provided a symmetry label for examination of chemical exchange processes. Tris[trimethylsilyl(t-butyl)cyclopentadienyl]cerium was prepared and the rate of interconversion between the C1 and C3 isomers was examined. The enthalpy difference between the two distereomers is 7.0 kJ/mol. The sterically demanding cyclopentadienyl ligands ansa-di-t-butylcyclopentadiene (Me2Si[(Me3C)2C5H3]2), ansa-bis(trimethylsilyl)cyclopentadiene (Me2Si[(Me3Si)2C5H3]2) and tetra-t-butylfulvalene and metallocene derivatives of the ligands were prepared and their structures were examined by single crystal X-ray crystallography. The effect that substituents on the cyclopentadienyl ring have on the pi-electron system of the ligand was examined through interaction between ligand and metal orbitals. A series of 1,3-disubstituted manganocenes was prepared and their electronic states were determined by solid-state magnetic susceptibility, electron paramagnetic resonance, X-ray crystallography, and variable temperature UV-vis spectroscopy. Spin-equilibria in [(Me3C)2C5H3]2Mn and [(Me3

  2. Observation of Different Catalytic Activity of Various 1-Olefins during Ethylene/1-Olefin Copolymerization with Homogeneous Metallocene Catalysts

    Directory of Open Access Journals (Sweden)

    Mingkwan Wannaborworn

    2011-01-01

    Full Text Available This research aimed to investigate the copolymerization of ethylene and various 1-olefins. The comonomer lengths were varied from 1-hexene (1-C6 up to 1-octadecene (1-C18 in order to study the effect of comonomer chain length on the activity and properties of the polymer in the metallocene/MAO catalyst system. The results indicated that two distinct cases can be described for the effect of 1-olefin chain length on the activity. Considering the short chain length comonomers, such as 1-hexene, 1-octene and 1-decene, it is obvious that the polymerization activity decreased when the length of comonomer was higher, which is probably due to increased steric hindrance at the catalytic center hindering the insertion of ethylene monomer to the active sites, hence, the polymerization rate decreased. On the contrary, for the longer chain 1-olefins, namely 1-dodecene, 1-tetradecene and 1-octadecene, an increase in the comonomer chain length resulted in better activity due to the opening of the gap aperture between Cp(centroid-M-Cp-(centroid, which forced the coordination site to open more. This effect facilitated the polymerization of the ethylene monomer at the catalytic sites, and thus, the activity increased. The copolymers obtained were further characterized using thermal analysis, X-ray diffraction spectroscopy and 13C-NMR techniques. It could be seen that the melting temperature and comonomer distribution were not affected by the 1-olefin chain length. The polymer crystallinity decreased slightly with increasing comonomer chain length. Moreover, all the synthesized polymers were typical LLDPE having random comonomer distribution.

  3. Observation of different catalytic activity of various 1-olefins during ethylene/1-olefin copolymerization with homogeneous metallocene catalysts.

    Science.gov (United States)

    Wannaborworn, Mingkwan; Praserthdam, Piyasan; Jongsomjit, Bunjerd

    2011-01-07

    This research aimed to investigate the copolymerization of ethylene and various 1-olefins. The comonomer lengths were varied from 1-hexene (1-C₆) up to 1-octadecene (1-C₁₈) in order to study the effect of comonomer chain length on the activity and properties of the polymer in the metallocene/MAO catalyst system. The results indicated that two distinct cases can be described for the effect of 1-olefin chain length on the activity. Considering the short chain length comonomers, such as 1-hexene, 1-octene and 1-decene, it is obvious that the polymerization activity decreased when the length of comonomer was higher, which is probably due to increased steric hindrance at the catalytic center hindering the insertion of ethylene monomer to the active sites, hence, the polymerization rate decreased. On the contrary, for the longer chain 1-olefins, namely 1-dodecene, 1-tetradecene and 1-octadecene, an increase in the comonomer chain length resulted in better activity due to the opening of the gap aperture between C(p)(centroid)-M-C(p)-(centroid), which forced the coordination site to open more. This effect facilitated the polymerization of the ethylene monomer at the catalytic sites, and thus, the activity increased. The copolymers obtained were further characterized using thermal analysis, X-ray diffraction spectroscopy and ¹³C-NMR techniques. It could be seen that the melting temperature and comonomer distribution were not affected by the 1-olefin chain length. The polymer crystallinity decreased slightly with increasing comonomer chain length. Moreover, all the synthesized polymers were typical LLDPE having random comonomer distribution.

  4. Reactions of Group 4 metallocene complexes with mono- and diphenylacetonitrile: formation of unusual four- and six-membered metallacycles.

    Science.gov (United States)

    Becker, Lisanne; Burlakov, Vladimir V; Arndt, Perdita; Spannenberg, Anke; Baumann, Wolfgang; Jiao, Haijun; Rosenthal, Uwe

    2013-03-25

    Reactions of Group 4 metallocene alkyne complexes [Cp'2M(η(2)-Me3SiC2SiMe3)] (1: M = Zr, Cp' = Cp* = η(5)-pentamethylcyclopentadienyl; 2 a: M = Ti, Cp' = Cp*, and 2 b: M = Ti, Cp'2 = rac-(ebthi) = rac-1,2-ethylene-1,1'-bis(η(5)-tetrahydroindenyl)) with diphenylacetonitrile (Ph2CHCN) and of the seven-membered zirconacyclocumulene 3 with phenylacetonitrile (PhCH2CN) were investigated. Different compounds were obtained depending on the metal, the cyclopentadienyl ligand and the reaction temperature. In the first step, Ph2CHCN coordinated to 1 to form [Cp*2Zr(η(2)-Me3SiC2SiMe3)(NCCHPh2)] (4). Higher temperatures led to elimination of the alkyne, coordination of a second Ph2CHCN and transformation of the nitriles to a keteniminate and an imine ligand in [Cp*2Zr(NC2Ph2)(NCHCHPh2)] (5). The conversion of 4 to 5 was monitored by using (1)H NMR spectroscopy. The analogue titanocene complex 2 a eliminated the alkyne first, which led directly to [Cp*2Ti(NC2Ph2)2] (6) with two keteniminate ligands. In contrast, the reaction of 2 b with diphenylacetonitrile involved a formal coupling of the nitriles to obtain the unusual four-membered titanacycle 7. An unexpected six-membered fused zirconaheterocycle (8) resulted from the reaction of 3 with PhCH2CN. The molecular structures of complexes 4, 5, 6, 7 and 8 were determined by X-ray crystallography. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Is the bipyridyl thorium metallocene a low-valent thorium complex? A combined experimental and computational study

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Wenshan; Lukens, Wayne W.; Zi, Guofu; Maron, Laurent; Walter, Marc D.

    2012-01-12

    Bipyridyl thorium metallocenes [5-1,2,4-(Me3C)3C5H2]2Th(bipy) (1) and [5-1,3-(Me3C)2C5H3]2Th(bipy) (2) have been investigated by magnetic susceptibility and computational studies. The magnetic susceptibility data reveal that 1 and 2 are not diamagnetic, but they behave as temperature independent paramagnets (TIPs). To rationalize this observation, density functional theory (DFT) and complete active space SCF (CASSCF) calculations have been undertaken, which indicated that Cp2Th(bipy) has indeed a Th(IV)(bipy2-) ground state (f0d0 2, S = 0), but the open-shell singlet (f0d1 1, S = 0) (almost degenerate with its triplet congener) is lying only 9.2 kcal/mol higher in energy. Complexes 1 and 2 react cleanly with Ph2CS to give [ 5-1,2,4-(Me3C)3C5H2]2Th[(bipy)(SCPh2)] (3) and [ 5-1,3-(Me3C)2C5H3]2Th[(bipy)(SCPh2)] (4), respectively, in quantitative conversions. Since no intermediates were observed experimentally, this reaction was also studied computationally. Coordination of Ph2CS to 2 in its S = 0 ground state is not possible, but Ph2CS can coordinate to 2 in its triplet state (S = 1) upon which a single electron transfer (SET) from the (bipy2-) fragment to Ph2CS followed by C-C coupling takes place.

  6. Evaluation of Alpha-Therapy with Radium-223-Dichloride in Castration Resistant Metastatic Prostate Cancer-the Role of Gamma Scintigraphy in Dosimetry and Pharmacokinetics.

    Science.gov (United States)

    Kairemo, Kalevi; Joensuu, Timo; Rasulova, Nigora; Kiljunen, Timo; Kangasmäki, Aki

    2015-07-30

    Radium-223-dichloride ((223)RaCl₂) is a new bone-seeking calcium analogue alpha-emitter, which has obtained marketing authorization for the treatment skeletal metastases of hormone-refractory prostate cancer. The current treatment regimen is based on six consecutive doses of (223)RaCl₂ at 4 week intervals and the administered activity dose, 50 kBq/kg per cycle is based on patient weight. We analyzed two patients using quantitative serial gamma imaging to estimate dosimetry in tumors and see possible pharmacokinetic differences in the treatment cycles. The lesions were rather well visualized in gamma scintigraphy in spite of low gamma activity (2.0-fold (1.8 vs. 3.6). Of these patients, patient 1 demonstrated a serum PSA response, whereas there was no PSA response in patient 2. From our data, there were maximally up to 4.0-fold differences (62.1 vs. 246.6 ) between the relative absorbed radiation doses between patients as calculated from the quantitative standardized imaging to be delivered in only two lesions, and in the same lesion the maximum difference in the cycles was up to 2.3-fold (107.4 vs. 246.6). Our recommendation based on statistical simulation analysis, is serial measurement at days 0-8 at least 3 times, this improve the accuracy significantly to study the lesion activities, half-lives or calculated relative absorbed radiation doses as calculated from the imaging. Both our patients had originally two metastatic sites in the imaging field; the former patient demonstrated a serum PSA response and the latter demonstrated no PSA response. In these two patients there was no significant difference in the lesion activities, half-lives or calculated relative absorbed radiation doses as calculated from the quantitative imaging. Our results, although preliminary, suggest that dose monitoring can be included as a part of this treatment modality. On the other hand, from the absorbed radiation doses, the response cannot be predicted because with very similar

  7. A Biodistribution and Toxicity Study of Cobalt Dichloride-N-Acetyl Cysteine in an Implantable MRI Marker for Prostate Cancer Treatment

    Energy Technology Data Exchange (ETDEWEB)

    Frank, Steven J., E-mail: sjfrank@mdanderson.org [Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Texas (United States); Johansen, Mary J. [Department of Experimental Therapeutics, The University of Texas MD Anderson Cancer Center, Texas (United States); Martirosyan, Karen S. [Department of Physics and Astronomy, The University of Texas at Brownsville, Texas (United States); Gagea, Mihai; Van Pelt, Carolyn S.; Borne, Agatha [Department of Veterinary Medicine, Surgery, and Pathology, The University of Texas MD Anderson Cancer Center, Texas (United States); Carmazzi, Yudith; Madden, Timothy [Department of Experimental Therapeutics, The University of Texas MD Anderson Cancer Center, Texas (United States)

    2013-03-15

    Purpose: C4, a cobalt dichloride-N-acetyl cysteine complex, is being developed as a positive-signal magnetic resonance imaging (MRI) marker to localize implanted radioactive seeds in prostate brachytherapy. We evaluated the toxicity and biodistribution of C4 in rats with the goal of simulating the systemic effects of potential leakage from C4 MRI markers within the prostate. Methods and Materials: 9-μL doses (equivalent to leakage from 120 markers in a human) of control solution (0.9% sodium chloride), 1% (proposed for clinical use), and 10% C4 solution were injected into the prostates of male Sprague-Dawley rats via laparotomy. Organ toxicity and cobalt disposition in plasma, tissues, feces, and urine were evaluated. Results: No C4-related morbidity or mortality was observed in the biodistribution arm (60 rats). Biodistribution was measurable after 10% C4 injection: cobalt was cleared rapidly from periprostatic tissue; mean concentrations in prostate were 163 μg/g and 268 μg/g at 5 and 30 minutes but were undetectable by 60 minutes. Expected dual renal-hepatic elimination was observed, with percentages of injected dose recovered in tissues of 39.0 ± 5.6% (liver), >11.8 ± 6.5% (prostate), and >5.3 ± 0.9% (kidney), with low plasma concentrations detected up to 1 hour (1.40 μg/mL at 5-60 minutes). Excretion in urine was 13.1 ± 4.6%, with 3.1 ± 0.54% recovered in feces by 24 hours. In the toxicity arm, 3 animals died in the control group and 1 each in the 1% and 10% groups from surgical or anesthesia-related complications; all others survived to scheduled termination at 14 days. No C4-related adverse clinical signs or organ toxicity were observed. Conclusion: C4-related toxicity was not observed at exposures at least 10-fold the exposure proposed for use in humans. These data demonstrating lack of systemic toxicity with dual routes of elimination in the event of in situ rupture suggest that C4 warrants further investigation as an MRI marker for prostate

  8. Spatial distribution of gamma-crystals in metallocene-made isotactic polypropylene crystallized under combined thermal and flow fields.

    Science.gov (United States)

    Wang, Yan; Pan, Ji-Lin; Mao, Yimin; Li, Zhong-Ming; Li, Liangbin; Hsiao, Benjamin S

    2010-05-27

    The present Article reports the relationships between molecular orientation, formation, and spatial distribution of gamma-crystals in metallocene-made isotactic polypropylene (m-iPP) samples prepared by two industrial processes: conventional injection molding (CIM) and oscillatory shear injection molding (OSIM), in which combined thermal and flow fields typically exist. In particular, spatial distributions of crystallinity, fraction of gamma-crystal (f(gamma)) with respect to alpha-crystal, and lamella-branched shish-kebab structure in the shaped samples were characterized by synchrotron two-dimensional (2D) wide-angle X-ray diffraction (WAXD) and small-angle X-ray scattering (SAXS) techniques. The results showed that the crystallinity in any given region of OSIM samples was always higher than that of CIM samples. The value of f(gamma) increased monotonously from skin to core in CIM samples, whereas the corresponding f(gamma) increased nonmonotonically in OSIM samples. The spatial distribution of gamma-crystal in OSIM samples can be explained by the epitaxial arrangement between gamma- and alpha-crystal in a lamella-branched shish-kebab structure. In the proposed model, the parent lamellae of alpha-crystal provide secondary nucleation sites for daughter lamellae of alpha-crystal and gamma-crystal, and the different content of parent lamellae results in varying amounts of gamma-crystal. In OSIM samples, the smallest parent-daughter ratio ([R]) = 1.38) in the core region led to the lowest fraction of gamma-crystal (0.57), but relatively higher gamma-crystal content (0.69) at 600 and 1200 mum depth of the samples (corresponding to [R] of 4.5 and 5.8, respectively). This is consistent with the proposed model where more parent lamellae provide more nucleation sites for crystallization, thus resulting in higher content of gamma-crystal. The melting behavior of CIM and OSIM samples was studied by differential scanning calorimetery (DSC). The observed double-melting peaks

  9. Synthesis, characterization and reactivity of group 4 metallocene bis(diphenylphosphino)acetylene complexes-a reactivity and bonding study.

    Science.gov (United States)

    Haehnel, Martin; Hansen, Sven; Schubert, Kathleen; Arndt, Perdita; Spannenberg, Anke; Jiao, Haijun; Rosenthal, Uwe

    2013-11-20

    A study of the coordination chemistry of bis(diphenylphosphino)acetylene, Ph2P-C≡C-PPh2, with selected group 4 metallocenes is presented. By substitution of the alkyne in complexes of the type Cp'2M(L)(η(2)-Me3SiC2SiMe3) (M = Ti, no L; M = Zr, L = pyridine; Cp' = substituted or unsubstituted bridged or unbridged η(5)-cyclopentadienyl), the expected mononuclear complexes Cp*2Ti(η(2)-Ph2PC2PPh2) (4Ti), (rac-ebthi)Ti(η(2)-Ph2PC2PPh2) (5Ti), and (rac-ebthi)Zr(η(2)-Ph2PC2PPh2) (5Zr) [ebthi = ethylenebis(tetrahydroindenyl)] were obtained. When [Cp2Zr] was used in the reaction of Cp2Zr(py)(η(2)-Me3SiC2SiMe3) with Ph2P-C≡C-PPh2, the dinuclear complex [Cp2Zr(η(2)-Ph2PC2PPh2)]2 (6) was formed and isolated in the solid state. In solution, this complex is in equilibrium with the very spectacular structure of complex 7b as the first example of such a highly strained four-membered heterometallacycle of a group 4 metal, involving the rare R2PCCR' fragment in the cyclic unit. Both the stability and reactivity of heterodisubstituted alkynes X-C≡C-X (X = NR2, PR2, SR, SiR3, etc.) themselves and also of their complexes are of general interest. Complex 6 did not react with a second [Cp2Zr] fragment to form a homobimetallic complex. In contrast, for (rac-ebthi)Zr(η(2)-Ph2PC2PPh2) (5Zr) this reaction occurs. In the reaction of complex 4Ti with the Ni(0) complex (Cy3P)2Ni(η(2)-C2H4) (Cy = cyclohexyl), C-P bond cleavage of the alkyne ligand resulted in the formation of the isolated complex [(Cy3P)Ni(μ-PPh2)]2 (11). The structure and bonding of the complexes were investigated by DFT analysis to compare the different possible coordination modes of the R2P-C≡C-PR2 ligand. For compound 7b, a flip-flop coordination of the phosphorus atoms was proposed. Complexes 4Ti, 5Ti, 5Zr, 6, and 11 were characterized by X-ray crystallography.

  10. Spatial Distribution of -Crystals in Metallocene-Made Isotactic Polypropylene Crystallized under Combined Thermal and Flow Fields

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Y.; Pan, J; Mao, Y; Li, Z; Li, L; Hsiao, B

    2010-01-01

    The present Article reports the relationships between molecular orientation, formation, and spatial distribution of {gamma}-crystals in metallocene-made isotactic polypropylene (m-iPP) samples prepared by two industrial processes: conventional injection molding (CIM) and oscillatory shear injection molding (OSIM), in which combined thermal and flow fields typically exist. In particular, spatial distributions of crystallinity, fraction of {gamma}-crystal (f{gamma}) with respect to {alpha}-crystal, and lamella-branched shish-kebab structure in the shaped samples were characterized by synchrotron two-dimensional (2D) wide-angle X-ray diffraction (WAXD) and small-angle X-ray scattering (SAXS) techniques. The results showed that the crystallinity in any given region of OSIM samples was always higher than that of CIM samples. The value of f{gamma} increased monotonously from skin to core in CIM samples, whereas the corresponding f{gamma} increased nonmonotonically in OSIM samples. The spatial distribution of {gamma}-crystal in OSIM samples can be explained by the epitaxial arrangement between {gamma}- and {alpha}-crystal in a lamella-branched shish-kebab structure. In the proposed model, the parent lamellae of {alpha}-crystal provide secondary nucleation sites for daughter lamellae of {alpha}-crystal and {gamma}-crystal, and the different content of parent lamellae results in varying amounts of {gamma}-crystal. In OSIM samples, the smallest parent-daughter ratio ([R] = 1.38) in the core region led to the lowest fraction of {gamma}-crystal (0.57), but relatively higher {gamma}-crystal content (0.69) at 600 and 1200 {micro}m depth of the samples (corresponding to [R] of 4.5 and 5.8, respectively). This is consistent with the proposed model where more parent lamellae provide more nucleation sites for crystallization, thus resulting in higher content of {gamma}-crystal. The melting behavior of CIM and OSIM samples was studied by differential scanning calorimetery (DSC). The

  11. Binuclear metallocenes of elements at the beginning of the transition series: The first heterometallic complex (n5:n5-C10H8)(n-CpTi)(n-CpNb)(u-H)2

    International Nuclear Information System (INIS)

    Demenovskii, D.A.; Nifant'er, I.E.; Zagorevskii, D.V.

    1986-01-01

    The authors synthesized the first mixed bis-metallocene complex (I) containing titanium and niobium. This complex was synthesized by the combined reduction of a mixture of metallocene dihalides as well as by the reaction of Cp 2 TiCl with lithium derivative. The yield of (I) in the first reaction was about 40% while it was more than 90% in the second. Complex (II), Cp 2 NbH 2 Li, is a new, convenient synthetic reagent readily formed in the crystalline state in the metallation of Cp 2 NbH 3 by butyllithium in toluene. The mass spectrum of (I) at 9-V ionizing potential shows a strong peak for only the molecular ion m/z 401 (for the ion with Ti 48); extensive dehydrogenation of the molecular ion occurs upon increasing the ionizing electron energy

  12. Isospecific polymerization of 1-hexene by C1-symmetric half-metallocene dimethyl complexes of group 4 metals with bidentate N-substituted iminomethylpyrrolyl ligands.

    Science.gov (United States)

    Yasumoto, Takahiro; Yamamoto, Keishi; Tsurugi, Hayato; Mashima, Kazushi

    2013-07-07

    Non-bridged half-metallocene dimethyl complexes of group 4 metals 2a-4a with an N-4-methoxyphenyl(iminomethyl)pyrrolyl ligand 1a were synthesized and characterized by NMR spectroscopy and X-ray analysis. Upon activation with [Ph3C][B(C6F5)4], these complexes became active catalysts for the polymerization of 1-hexene. A series of hafnium complexes with various N-substituents on the imine group of ligands 1b-1g were also prepared and applied as catalysts for 1-hexene polymerization. The activation parameters for the exchange process between the two methyl groups bound to the metal for Cp*MMe2(R-pyr) complexes were estimated by NMR shape analysis at various temperatures. The findings indicated that the transition state of the ligand flipping process might be associated with the isoselectivity of the polymerization reaction.

  13. The potential of {sup 223}Ra and {sup 18}F-fluoride imaging to predict bone lesion response to treatment with {sup 223}Ra-dichloride in castration-resistant prostate cancer

    Energy Technology Data Exchange (ETDEWEB)

    Murray, Iain; Chittenden, Sarah J.; Denis-Bacelar, Ana M.; Flux, Glenn D. [Royal Marsden NHS Foundation Trust, Joint Department of Physics, Sutton, Surrey (United Kingdom); The Institute of Cancer Research, London (United Kingdom); Hindorf, Cecilia [Royal Marsden NHS Foundation Trust, Joint Department of Physics, Sutton, Surrey (United Kingdom); The Institute of Cancer Research, London (United Kingdom); Skaane University Hospital, Department of Radiation Physics, Lund (Sweden); Parker, Christopher C. [Royal Marsden NHS Foundation Trust, Department of Urology, Sutton (United Kingdom); Chua, Sue [Royal Marsden NHS Foundation Trust, Department of Nuclear Medicine, Sutton (United Kingdom)

    2017-10-15

    The aims of this study were to calculate bone lesion absorbed doses resulting from a weight-based administration of {sup 223}Ra-dichloride, to assess the relationship between those doses and corresponding {sup 18}F-fluoride uptake and to assess the potential of quantitative {sup 18}F-fluoride imaging to predict response to treatment. Five patients received two intravenous injections of {sup 223}Ra-dichloride, 6 weeks apart, at 110 kBq/kg whole-body weight. The biodistribution of {sup 223}Ra in metastatic lesions as a function of time after administration as well as associated lesion dosimetry were determined from serial {sup 223}Ra scans. PET/CT imaging using {sup 18}F-fluoride was performed prior to the first treatment (baseline), and at week 6 immediately before the second treatment and at week 12 after baseline. Absorbed doses to metastatic bone lesions ranged from 0.6 Gy to 44.1 Gy. For individual patients, there was an average factor difference of 5.3 (range 2.5-11.0) between the maximum and minimum lesion dose. A relationship between lesion-absorbed doses and serial changes in {sup 18}F-fluoride uptake was demonstrated (r{sup 2} = 0.52). A log-linear relationship was demonstrated (r{sup 2} = 0.77) between baseline measurements of {sup 18}F-fluoride uptake prior to {sup 223}Ra-dichloride therapy and changes in uptake 12 weeks after the first cycle of therapy. Correlations were also observed between both {sup 223}Ra and {sup 18}F-fluoride uptake in lesions (r = 0.75) as well as between {sup 223}Ra absorbed dose and {sup 18}F-fluoride uptake (r = 0.96). There is both inter-patient and intra-patient heterogeneity of absorbed dose estimates to metastatic lesions. A relationship between {sup 223}Ra lesion absorbed dose and subsequent lesion response was observed. Analysis of this small group of patients suggests that baseline uptake of {sup 18}F-fluoride in bone metastases is significantly correlated with corresponding uptake of {sup 223}Ra, the associated {sup 223

  14. Evaluation of Alpha-Therapy with Radium-223-Dichloride in Castration Resistant Metastatic Prostate Cancer—the Role of Gamma Scintigraphy in Dosimetry and Pharmacokinetics

    Directory of Open Access Journals (Sweden)

    Kalevi Kairemo

    2015-07-01

    Full Text Available Radium-223-dichloride (223RaCl2 is a new bone-seeking calcium analogue alpha-emitter, which has obtained marketing authorization for the treatment skeletal metastases of hormone-refractory prostate cancer. The current treatment regimen is based on six consecutive doses of 223RaCl2 at 4 week intervals and the administered activity dose, 50 kBq/kg per cycle is based on patient weight. We analyzed two patients using quantitative serial gamma imaging to estimate dosimetry in tumors and see possible pharmacokinetic differences in the treatment cycles. The lesions were rather well visualized in gamma scintigraphy in spite of low gamma activity (<1.1% gamma radiation at 0, 7 and 28 days using 30–60 min acquisition times. Both our patients analyzed in serial gamma imagings, had two lesions in the gamma imaging field, the mean counts of the relative intensity varied from 27.8 to 36.5 (patient 1, and from 37.4 to 82.2 (patient 2. The half-lives varied from 1.8 days to 4.5 days during the six cycles (patient 1, and from 1.5 days to 3.6 days (patient 2, respectively. In the lesion half-lives calculated from the imaging the maximum difference between the treatment cycles in the same lesion was 2.0-fold (1.8 vs. 3.6. Of these patients, patient 1 demonstrated a serum PSA response, whereas there was no PSA response in patient 2. From our data, there were maximally up to 4.0-fold differences (62.1 vs. 246.6 between the relative absorbed radiation doses between patients as calculated from the quantitative standardized imaging to be delivered in only two lesions, and in the same lesion the maximum difference in the cycles was up to 2.3-fold (107.4 vs. 246.6. Our recommendation based on statistical simulation analysis, is serial measurement at days 0–8 at least 3 times, this improve the accuracy significantly to study the lesion activities, half-lives or calculated relative absorbed radiation doses as calculated from the imaging. Both our patients had

  15. Vanadium NMR Chemical Shifts of (Imido)vanadium(V) Dichloride Complexes with Imidazolin-2-iminato and Imidazolidin-2-iminato Ligands: Cooperation with Quantum-Chemical Calculations and Multiple Linear Regression Analyses.

    Science.gov (United States)

    Yi, Jun; Yang, Wenhong; Sun, Wen-Hua; Nomura, Kotohiro; Hada, Masahiko

    2017-11-30

    The NMR chemical shifts of vanadium ( 51 V) in (imido)vanadium(V) dichloride complexes with imidazolin-2-iminato and imidazolidin-2-iminato ligands were calculated by the density functional theory (DFT) method with GIAO. The calculated 51 V NMR chemical shifts were analyzed by the multiple linear regression (MLR) analysis (MLRA) method with a series of calculated molecular properties. Some of calculated NMR chemical shifts were incorrect using the optimized molecular geometries of the X-ray structures. After the global minimum geometries of all of the molecules were determined, the trend of the observed chemical shifts was well reproduced by the present DFT method. The MLRA method was performed to investigate the correlation between the 51 V NMR chemical shift and the natural charge, band energy gap, and Wiberg bond index of the V═N bond. The 51 V NMR chemical shifts obtained with the present MLR model were well reproduced with a correlation coefficient of 0.97.

  16. The preparation of nanosized polyethylene particles via novel heterogeneous non-metallocene catalyst (m-CH3PhO)TiCl3/CNTs/AlEt3

    Science.gov (United States)

    Wang, J.; Guo, J. P.; Yi, J. J.; Huang, Q. G.; Li, H. M.; Li, Y. F.; Gao, K. J.; Yang, W. T.

    2014-08-01

    This paper reports the preparation of coral-shaped topological morphology nascent polyethylene (PE) particles promoted by the novel heterogeneous non-metallocene catalyst (m-CH3PhO)TiCl3/carbon nanotubes (CNTs), with AlEt3 used as a cocatalyst. Scanning electron microscope (SEM), high resolution transmission electron microscope (HR-TEM) and inductively coupled plasma (ICP) emission spectroscopy were used to determine the morphology of the catalyst particles and the content of (m-CH3PhO)TiCl3. The carbon nanotube surface was treated with Grignard Reagent prior to reacting with (m-CH3PhO)TiCl3. The catalyst system could effectively catalyze ethylene polymerization and ethylene with 1- hexene copolymerization, the catalytic activity could reach up to 5.8 kg/((gTi)h). Morphology of the obtained polymer particles by SEM and HR-TEM technique revealed that the nascent polyethylene particles looked like coral shape in micro-size. The multiwalled carbon nanotubes (MWCNTs) supported catalysts polymerized ethylene to form polymer nanocomposite in situ. The microscopic examination of this nanocomposite revealed that carbon nanoparticles in PE matrix had a good distribution and the cryogenically fractured surface was ductile-like when polymerization time was 2 min.

  17. Metallocene electrochemistry. 3. Reduction-oxidation study of dicyclopentadienyl compounds of ruthenium and titanium in Lewis acid-base molten salts

    Energy Technology Data Exchange (ETDEWEB)

    Gale, R.J.; Job, R.

    1981-01-01

    Voltammetry at vitreous C electrodes of Ru(eta/sup 5/-C/sub 5/H/sub 5/)/sub 2/ and Ti(eta/sup 5/-C/sub 5/H/sub 5/)/sub 2/Cl/sub 2/ in the 0.8:1 molar ratio AlCl/sub 3/-1 butylpyridinium chloride melt reveals an irreversible oxidation (E/sub p/2/ = = +0.68 V, 100 mV s/sup -1/) and a reversible 1e reduction (E/sub 1/2/ = -0.65 V vs. SCE), respectively. These electrode potentials are comparable to those found for each species in nonaqueous, organic electrolytes. In the acidic melts (excess AlCl/sub 3/), Ru(eta/sup 5/-C/sub 5/H/sub 5/)/sub 2/ is oxidized by multistep pathways sensitive to the melt composition, while the Ti(eta/sup 5/-C/sub 5/H/sub 5/)/sup 2 +/ dication is reduced by a reversible 1e step (E/sub 1/2/ = +0.67 V vs. SCE, 2:1 mole ratio melt) in a pC1/sup -/ dependent process. Electrochemical behavior of each of these metallocenes in neutral 1:1 molar ratio melts is complicated.

  18. A comparative study of the reactivity of Zr(IV), Hf(IV) and Th(IV) metallocene complexes: Thorium is not a Group IV metal after all

    International Nuclear Information System (INIS)

    Jantunen, Kimberly C.; Scott, Brian L.; Kiplinger, Jaqueline L.

    2007-01-01

    Thorium(IV) is often considered to show similar chemistry to Group IV transition metals. However, studies in our laboratory have shown that this generalization is incorrect. This report presents direct comparisons where the Th(IV) metallocene complexes (C 5 Me 5 ) 2 ThR 2 (R = CH 3 , Ph, CH 2 Ph) undergo unique chemical reactivity with pyridine, 2-picoline, pyridine N-oxide, 2-picoline N-oxide, and benzonitrile, while the Group IV metal analogues (C 5 R 5 ) 2 M(CH 3 ) 2 (R = H, CH 3 ; M = Zr, Hf) do not. We also report revised high-yield syntheses for the zirconium and hafnium starting materials, (C 5 H 5 ) 2 MR 2 (M = Zr, Hf; R = CH 3 , Ph, CH 2 Ph), using Grignard reagents for alkylation in addition to the X-ray crystal structures of (C 5 H 5 ) 2 Hf(Ph) 2 and (C 5 H 5 ) 2 Hf(CH 2 Ph) 2

  19. Unravelling the potential of nitric acid as a surface modifier for improving the hemocompatibility of metallocene polyethylene for blood contacting devices

    Directory of Open Access Journals (Sweden)

    Muthu Vignesh Vellayappan

    2016-01-01

    Full Text Available Design of blood compatible surfaces is obligatory to minimize platelet surface interactions and improve the thromboresistance of foreign surfaces when they are utilized as biomaterials particularly for blood contacting devices. Pure metallocene polyethylene (mPE and nitric acid (HNO3 treated mPE antithrombogenicity and hydrophilicity were investigated. The contact angle of the mPE treated with HNO3 decreased. Surface of mPE and HNO3 treated mPE investigated with FTIR revealed no major changes in its functional groups. 3D Hirox digital microscopy, SEM and AFM images show increased porosity and surface roughness. Blood coagulation assays prothrombin time (PT and activated partial thromboplastin time (APTT were delayed significantly (P < 0.05 for HNO3 treated mPE. Hemolysis assay and platelet adhesion of the treated surface resulted in the lysis of red blood cells and platelet adherence, respectively indicating improved hemocompatibility of HNO3 treated mPE. To determine that HNO3 does not deteriorate elastic modulus of mPE, the elastic modulus of mPE and HNO3 treated mPE was compared and the result shows no significant difference. Hence, the overall observation suggests that the novel HNO3 treated mPE may hold great promises to be exploited for blood contacting devices like grafts, catheters, and etc.

  20. Reactions of group 4 metallocene alkyne complexes with carbodiimides: experimental and theoretical studies of the structure and bonding of five-membered hetero-metallacycloallenes.

    Science.gov (United States)

    Kaleta, Katharina; Ruhmann, Martin; Theilmann, Oliver; Beweries, Torsten; Roy, Subhendu; Arndt, Perdita; Villinger, Alexander; Jemmis, Eluvathingal D; Schulz, Axel; Rosenthal, Uwe

    2011-04-13

    The reaction of the low-valent metallocene(II) sources Cp(2)Ti(η(2)-Me(3)SiC(2)SiMe(3)) (7) and Cp(2)Zr(py)(η(2)-Me(3)SiC(2)SiMe(3)) (11, Cp = η(5)-cyclopentadienyl, py = pyridine) with carbodiimides RN═C═NR (R = Cy, i-Pr, p-Tol) leads to the formation of five membered hetero-metallacycloallenes Cp(2)M{Me(3)SiC═C═C[N(SiMe(3))(R)]-N(R)} (9M-R) (M = Ti, R = i-Pr; M = Zr, R = Cy, i-Pr, p-Tol). Elimination of the alkyne (as the hitherto known reactivity of titanocene and zirconocene alkyne complexes would suggest) was not observed. The molecular structures of the obtained complexes were confirmed by X-ray studies. Moreover, the structure and bonding of the complexes 9Zr-Cy and 9Zr-p-Tol was investigated by DFT calculations. © 2011 American Chemical Society

  1. Catalytic N2-to-NH3 Conversion by Fe at Lower Driving Force: A Proposed Role for Metallocene-Mediated PCET.

    Science.gov (United States)

    Chalkley, Matthew J; Del Castillo, Trevor J; Matson, Benjamin D; Roddy, Joseph P; Peters, Jonas C

    2017-03-22

    We have recently reported on several Fe catalysts for N 2 -to-NH 3 conversion that operate at low temperature (-78 °C) and atmospheric pressure while relying on a very strong reductant (KC 8 ) and acid ([H(OEt 2 ) 2 ][BAr F 4 ]). Here we show that our original catalyst system, P 3 B Fe, achieves both significantly improved efficiency for NH 3 formation (up to 72% for e - delivery) and a comparatively high turnover number for a synthetic molecular Fe catalyst (84 equiv of NH 3 per Fe site), when employing a significantly weaker combination of reductant (Cp* 2 Co) and acid ([Ph 2 NH 2 ][OTf] or [PhNH 3 ][OTf]). Relative to the previously reported catalysis, freeze-quench Mössbauer spectroscopy under turnover conditions suggests a change in the rate of key elementary steps; formation of a previously characterized off-path borohydrido-hydrido resting state is also suppressed. Theoretical and experimental studies are presented that highlight the possibility of protonated metallocenes as discrete PCET reagents under the present (and related) catalytic conditions, offering a plausible rationale for the increased efficiency at reduced driving force of this Fe catalyst system.

  2. Unravelling the potential of nitric acid as a surface modifier for improving the hemocompatibility of metallocene polyethylene for blood contacting devices.

    Science.gov (United States)

    Vellayappan, Muthu Vignesh; Jaganathan, Saravana Kumar; Muhamad, Ida Idayu

    2016-01-01

    Design of blood compatible surfaces is obligatory to minimize platelet surface interactions and improve the thromboresistance of foreign surfaces when they are utilized as biomaterials particularly for blood contacting devices. Pure metallocene polyethylene (mPE) and nitric acid (HNO3) treated mPE antithrombogenicity and hydrophilicity were investigated. The contact angle of the mPE treated with HNO3 decreased. Surface of mPE and HNO3 treated mPE investigated with FTIR revealed no major changes in its functional groups. 3D Hirox digital microscopy, SEM and AFM images show increased porosity and surface roughness. Blood coagulation assays prothrombin time (PT) and activated partial thromboplastin time (APTT) were delayed significantly (P < 0.05) for HNO3 treated mPE. Hemolysis assay and platelet adhesion of the treated surface resulted in the lysis of red blood cells and platelet adherence, respectively indicating improved hemocompatibility of HNO3 treated mPE. To determine that HNO3 does not deteriorate elastic modulus of mPE, the elastic modulus of mPE and HNO3 treated mPE was compared and the result shows no significant difference. Hence, the overall observation suggests that the novel HNO3 treated mPE may hold great promises to be exploited for blood contacting devices like grafts, catheters, and etc.

  3. A comparative study of the reactivity of Zr(IV), Hf(IV) and Th(IV) metallocene complexes: Thorium is not a Group IV metal after all

    Energy Technology Data Exchange (ETDEWEB)

    Jantunen, Kimberly C.; Scott, Brian L. [Los Alamos National Laboratory, Mail Stop J514, Los Alamos, NM 87545 (United States); Kiplinger, Jaqueline L. [Los Alamos National Laboratory, Mail Stop J514, Los Alamos, NM 87545 (United States)], E-mail: kiplinger@lanl.gov

    2007-10-11

    Thorium(IV) is often considered to show similar chemistry to Group IV transition metals. However, studies in our laboratory have shown that this generalization is incorrect. This report presents direct comparisons where the Th(IV) metallocene complexes (C{sub 5}Me{sub 5}){sub 2}ThR{sub 2} (R = CH{sub 3}, Ph, CH{sub 2}Ph) undergo unique chemical reactivity with pyridine, 2-picoline, pyridine N-oxide, 2-picoline N-oxide, and benzonitrile, while the Group IV metal analogues (C{sub 5}R{sub 5}){sub 2}M(CH{sub 3}){sub 2} (R = H, CH{sub 3}; M = Zr, Hf) do not. We also report revised high-yield syntheses for the zirconium and hafnium starting materials, (C{sub 5}H{sub 5}){sub 2}MR{sub 2} (M = Zr, Hf; R = CH{sub 3}, Ph, CH{sub 2}Ph), using Grignard reagents for alkylation in addition to the X-ray crystal structures of (C{sub 5}H{sub 5}){sub 2}Hf(Ph){sub 2} and (C{sub 5}H{sub 5}){sub 2}Hf(CH{sub 2}Ph){sub 2}.

  4. The preparation of nanosized polyethylene particles via novel heterogeneous non-metallocene catalyst (m-CH3PhO)TiCl3/CNTs/AlEt3

    International Nuclear Information System (INIS)

    Wang, J; Guo, J P; Huang, Q G; Li, Y F; Yang, W T; Yi, J J; Li, H M; Gao, K J

    2014-01-01

    This paper reports the preparation of coral-shaped topological morphology nascent polyethylene (PE) particles promoted by the novel heterogeneous non-metallocene catalyst (m-CH 3 PhO)TiCl 3 /carbon nanotubes (CNTs), with AlEt 3 used as a cocatalyst. Scanning electron microscope (SEM), high resolution transmission electron microscope (HR-TEM) and inductively coupled plasma (ICP) emission spectroscopy were used to determine the morphology of the catalyst particles and the content of (m-CH 3 PhO)TiCl 3 . The carbon nanotube surface was treated with Grignard Reagent prior to reacting with (m-CH 3 PhO)TiCl 3 . The catalyst system could effectively catalyze ethylene polymerization and ethylene with 1- hexene copolymerization, the catalytic activity could reach up to 5.8 kg/((gTi)h). Morphology of the obtained polymer particles by SEM and HR-TEM technique revealed that the nascent polyethylene particles looked like coral shape in micro-size. The multiwalled carbon nanotubes (MWCNTs) supported catalysts polymerized ethylene to form polymer nanocomposite in situ. The microscopic examination of this nanocomposite revealed that carbon nanoparticles in PE matrix had a good distribution and the cryogenically fractured surface was ductile-like when polymerization time was 2 min

  5. Alargamento da distribuição de massa molar de polímeros sintetizados com catalisadores metalocênicos dual-site Broadening of molecular weight distribution of polymers synthesized by metallocene-based dual-site catalysts

    Directory of Open Access Journals (Sweden)

    João H. Z. dos Santos

    2008-01-01

    Full Text Available The main topics related to the use of dual-site catalysts in the production of polymers with broad molecular weight distribution are reviewed. The polymerization using dual-site catalysts is more economical and allows to produce a higher quality product than other processes, such as polymer blend and multistage reactors. However, the formulation of these catalysts is quite complicated since the same catalyst must produce distinct polymer grades. In addition, the release of patents concerning the combination of metallocenes and new technologies for polymerization shows that polymerization processes using dual-site catalysts are of current industrial interest.

  6. Broadening of molecular weight distribution of polymers synthesized by metallocene-based dual-site catalysts; Alargamento da distribuicao de massa molar de polimeros sintetizados com catalisadores metalocenicos dual-site

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Joao H.Z. dos [Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS (Brazil). Inst. de Quimica]. E-mail: jhzds@iq.ufrgs.br; Fisch, Adriano G.; Cardozo, Nilo S.M.; Secchi, Argimiro R. [Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS (Brazil). Dept. de Engenharia Quimica

    2008-07-01

    The main topics related to the use of dual-site catalysts in the production of polymers with broad molecular weight distribution are reviewed. The polymerization using dual-site catalysts is more economical and allows to produce a higher quality product than other processes, such as polymer blend and multistage reactors. However, the formulation of these catalysts is quite complicated since the same catalyst must produce distinct polymer grades. In addition, the release of patents concerning the combination of metallocenes and new technologies for polymerization shows that polymerization processes using dual-site catalysts are of current industrial interest. (author)

  7. Identifying sarcopenia.

    Science.gov (United States)

    Abellan van Kan, Gabor; Houles, Mathieu; Vellas, Bruno

    2012-09-01

    The present review describes and discusses the currently available definitions for sarcopenia from consensus studies. Different sarcopenia definitions have been proposed in these last years. Six main approaches to an operative definition of sarcopenia have been identified. Although the first definitions were solely based on the assessment of the amount of muscle mass, current definitions seem to consistently recognize a bi-dimensional nature of sarcopenia. So, these approaches imply the need of simultaneously assessing both age-related quantitative (i.e. amount of muscle mass) and qualitative (i.e. muscle strength and function) declines of skeletal muscle. Although current consensus exists about a bi-dimensional nature, the proposed approaches to measure sarcopenia are characterized by methodological differences. The majority of the operative definitions proposes to assess muscle mass as an index of appendicular muscle mass divided by squared height (evaluated by dual energy X-ray absorptiometry), assess strength using hand-held dynamometers, and assess function by evaluating gait speed at habitual pace over a short distance. Nevertheless, the clinically relevant thresholds and how to combine the three aspects in an operative definition in order to identify sarcopenia are heterogeneous. A main drawback is that supportive empirical data are missing for these conceptual definitions regarding the risk-assessment of different clinically significant adverse outcomes.

  8. An aqueous all-organic redox-flow battery employing a (2,2,6,6-tetramethylpiperidin-1-yl)oxyl-containing polymer as catholyte and dimethyl viologen dichloride as anolyte

    Science.gov (United States)

    Hagemann, Tino; Winsberg, Jan; Grube, Mandy; Nischang, Ivo; Janoschka, Tobias; Martin, Norbert; Hager, Martin D.; Schubert, Ulrich S.

    2018-02-01

    Herein we present a new redox-flow battery (RFB) that employs a (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO) containing copolymer (P1) as catholyte and the viologen derivative N,N‧-dimethyl-4,4‧-bipyridinium dichloride (MV) as anolyte in an aqueous sodium chloride solution. This is the first time that a combination of an organic polymer and a low-molar-mass organic redox-active material is presented. The electrochemical behavior of the utilized charge-storage materials were investigated by cyclic voltammetry (CV) and feature reversible redox-reactions at E½ = 0.7 V (TEMPO/TEMPO+) and E½ = -0.6 V vs. AgCl/Ag (MV++/MV+•), which lead to a promising cell voltage of 1.3 V in the subsequent battery application. Studies were performed to determine the most suitable anion-exchange membrane (AEM), the ideal conducting salt concentration and the optimal flow rate. The resulting battery reveals a stable charge/discharge performance over 100 consecutive cycles with coulombic efficiencies of up to 95%, a high energy efficiency of 85% and an overall energy density of the electrolyte system of 3.8 W h L-1.

  9. Strong Lewis acids of air-stable metallocene bis(perfluorooctanesulfonate)s as high-efficiency catalysts for carbonyl-group transformation reactions.

    Science.gov (United States)

    Qiu, Renhua; Xu, Xinhua; Peng, Lifeng; Zhao, Yalei; Li, Ningbo; Yin, Shuangfeng

    2012-05-14

    Strong Lewis acids of air-stable metallocene bis(perfluorooctanesulfonate)s [M(Cp)(2)][OSO(2)C(8)F(17)](2)⋅nH(2)O⋅THF (M = Zr (2 a⋅3 H(2)O⋅THF), M = Ti (2 b⋅2 H(2)O⋅THF)) were synthesized by the reaction of [M(Cp)(2)]Cl(2) (M = Zr (1 a), M = Ti (1 b)) with nBuLi and C(8)F(17)SO(3)H (2 equiv) or with C(8)F(17)SO(3)Ag (2 equiv). The hydrate numbers (n) of these complexes were variable, changing from 0 to 4 depending on conditions. In contrast to well-known metallocene triflates, these complexes suffered no change in open air for a year. thermogravimetry-differential scanning calorimetry (TG-DSC) analysis showed that 2 a and 2 b were thermally stable at 300 and 180 °C, respectively. These complexes exhibited unusually high solubility in polar organic solvents. Conductivity measurement showed that the complexes (2 a and 2 b) were ionic dissociation in CH(3)CN solution. X-ray analysis result confirmed 2 a⋅3 H(2)O⋅THF was a cationic organometallic Lewis acid. UV/Vis spectra showed a significant red shift due to the strong complex formation between 10-methylacridone and 2 a. Fluorescence spectra showed that the Lewis acidity of 2 a fell between those of Sc(3+) (λ(em)=474 nm) and Fe(3+) (λ(em)=478 nm). ESR spectra showed the Lewis acidity of 2 a (0.91 eV) was at the same level as that of Sc(3+) (1.00 eV) and Y(3+) (0.85 eV), while the Lewis acidity of 2 b (1.06 eV) was larger than that of Sc(3+) (1.00 eV) and Y(3+) (0.85 eV). They showed high catalytic ability in carbonyl-compound transformation reactions, such as the Mannich reaction, the Mukaiyama aldol reaction, allylation of aldehydes, the Friedel-Crafts acylation of alkyl aromatic ethers, and cyclotrimerization of ketones. Moreover, the complexes possessed good reusability. On account of their excellent catalytic efficiency, stability, and reusability, the complexes will find broad catalytic applications in organic synthesis. Copyright © 2012

  10. Microwave-Assisted Dip Coating of Aloe Vera on Metallocene Polyethylene Incorporated with Nano-Rods of Hydroxyapaptite for Bone Tissue Engineering

    Directory of Open Access Journals (Sweden)

    Hairong Wang

    2017-10-01

    Full Text Available Bone tissue engineering widely explores the use of ceramic reinforced polymer-matrix composites. Among the various widely-used ceramic reinforcements, hydroxyapatite is an undisputed choice due to its inherent osteoconductive nature. In this study, a novel nanocomposite comprising metallocene polyethylene (mPE incorporated with nano-hydroxyapaptite nanorods (mPE-nHA was synthesized and dip coated with Aloe vera after subjecting it to microwave treatment. The samples were characterized using contact angle, Fourier transform infrared spectroscopy (FTIR, scanning electron microscope (SEM, atomic force microscopy (AFM and 3D Hirox microscopy scanning. Contact angle results show that the hydrophilicity of mPE-nHA improved notably with the coating of Aloe vera. The surface topology and increase in surface roughness were observed using the SEM, AFM and 3D Hirox microscopy. Blood compatibility assays of pure mPE and the Aloe vera coated nanocomposite were performed. The prothrombin time (PT was delayed by 1.06% for 24 h Aloe-vera-treated mPE-nHA compared to the pristine mPE-nHA. Similarly, the 24 h Aloe-vera-coated mPE-nHA nanocomposite prolonged the activated partial thromboplastin time (APTT by 41 s against the control of pristine mPE-nHA. The hemolysis percentage was also found to be the least for the 24 h Aloe-vera-treated mPE-nHA which was only 0.2449% compared to the pristine mPE-nHA, which was 2.188%. To conclude, this novel hydroxyapatite-reinforced, Aloe-vera-coated mPE with a better mechanical and anti-thrombogenic nature may hold a great potential to be exploited for bone tissue engineering applications.

  11. Journal of Chemical Sciences | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Reaction of ,-unsaturated aromatic carboxylic acids with KBr and H2O2 in the presence of Na2MoO4 ⋅ H2O in aqueous medium affords -bromo alkenes in high yields. Metallocene dichlorides, Cp2MCl2 (M = Ti, Zr, or V) catalyse polymerisation of olefins in aqueous medium to afford high molecular weight polymers ...

  12. Computational Study of the Effect of Confinement within Microporous Structures on the Activity and Selectivity of Metallocene Catalysts for Ethylene Oligomerization

    KAUST Repository

    Toulhoat, Hervé

    2011-03-02

    The effect of confinement within some zeolitic structures on the activity and selectivity of metallocene catalysts for the ethylene oligomerization has been investigated using grand canonical Monte Carlo simulations (GCMC). The following zeolite (host) frameworks displaying different pore sizes, have been studied as solid hosts: mazzite (MAZ), AIPO-8 (AET), UTD-1F (DON), faujasite (FAU), and VPI-5 (VFI). Intermediates and transition states involved in the ethylene trimerization reaction catalyzed by a Ti-based catalyst [(η5-C5H4CMe2C6H 5)TiCl3/MAO] have been used as sorbates (guests). We have demonstrated linear correlations with slope aH,j between the adsorption enthalpy and the molecular volume Vm of the sorbates, each holding for a given microporous host below a host-specific threshold V mmax,j. Beyond this maximal molecular volume, the adsorption vanishes due to steric exclusion. aH,j increases, and Vmmax,j decreases with decreasing host pore size, in line with the confinement concept. We moreover showed that, in the limit of vanishing loading (Henry regime), the enthalpies and entropies of adsorption in a given host are linearly correlated. We have defined a host-specific confinement compensation temperature a j, which refers to a temperature where the stabilizing adsorption enthalpic interactions are canceled out against the loss in entropy. However, calculated aj are much larger than the operating temperatures. With a setup microkinetic model, we predict that the activity and selectivity of the confined Ti-catalyst in ethylene oligomerization can be significantly altered with respect to homogeneous phase conditions, since the adsorption free energies of transition states and intermediates also become functions of aH,j and Vm. We have applied this theory to predict the optimum host pore size to get maximum α-octene production, instead of α-hexene, which is primarily produced in the homogeneous phase. We also predict a significantly increased activity for

  13. Chiral and achiral (imino)phenoxy-based cationic group 4 non-metallocene complexes as catalysts for polymerization of renewable α-methylene-γ-butyrolactones.

    Science.gov (United States)

    Gowda, Ravikumar R; Chen, Eugene Y-X

    2013-07-07

    Protonolysis of M(Bn)4 (M = Zr, Ti; Bn = benzyl) with equimolar 2,4-di-tert-butyl-6-[(2,6-diisopropylphenylimino)methyl]phenol [(2,6-(i)Pr2C6H3)N=C(3,5-(t)Bu2C6H2)OH] in toluene at -30 °C to 25 °C cleanly affords the corresponding achiral (imino)phenoxy-tribenzyl complexes, [(2,6-(i)Pr2C6H3)N=C(3,5-(t)Bu2C6H2)O]Zr(Bn)3 (1) and [(2,6-(i)Pr2C6H3)N=C(3,5-(t)Bu2C6H2)O]Ti(Bn)3 (2). A chiral dibenzyl complex 3 incorporating the unsymmetric, tetradentate amino(imino)bis(phenoxy) ligand, [2,4-Br2C6H2(O)(6-CH2(NC5H9))CH2N=CH(2-adamantyl-4-MeC6H2O)]Zr(Bn)2 (3), has also been prepared using the same protonolysis protocol. Abstractive activation of 1 with B(C6F5)3·THF in CD2Cl2 at room temperature (RT) affords clean, quantitative formation of the corresponding zirconium cation [((2,6-(i)Pr2C6H3)N=C(3,5-(t)Bu2C6H2)O)Zr(Bn)2(THF)](+)[BnB(C6F5)3](-) (4). Likewise, benzyl abstraction of 2 with B(C6F5)3·THF in CD2Cl2 at RT generates the cationic titanium complex [((2,6-(i)Pr2C6H3)N=C(3,5-(t)Bu2C6H2)O)Ti(Bn)2(THF)](+)[BnB(C6F5)3](-) (5), accompanied by a small amount of decomposed species as a result of C6F5 transfer. The dibenzyl cations 4 and 5 have been characterized spectroscopically, and their structures have been confirmed by single crystal X-ray diffraction analysis. Characteristics of the coordination polymerization of renewable α-methylene-γ-butyrolactone monomers by the cationic catalysts derived from achiral complexes 1 and 2 as well as chiral complex 3 have been investigated, representing the first study of such polymerization by non-metallocene catalysts.

  14. Computational study of the effect of confinement within microporous structures on the activity and selectivity of metallocene catalysts for ethylene oligomerization.

    Science.gov (United States)

    Toulhoat, Hervé; Fomena, Mireille Lontsi; de Bruin, Theodorus

    2011-03-02

    The effect of confinement within some zeolitic structures on the activity and selectivity of metallocene catalysts for the ethylene oligomerization has been investigated using grand canonical Monte Carlo simulations (GCMC). The following zeolite (host) frameworks displaying different pore sizes, have been studied as solid hosts: mazzite (MAZ), AIPO-8 (AET), UTD-1F (DON), faujasite (FAU), and VPI-5 (VFI). Intermediates and transition states involved in the ethylene trimerization reaction catalyzed by a Ti-based catalyst [(η(5)-C(5)H(4)CMe(2)C(6)H(5))TiCl(3)/MAO] have been used as sorbates (guests). We have demonstrated linear correlations with slope a(H,j) between the adsorption enthalpy and the molecular volume V(m) of the sorbates, each holding for a given microporous host below a host-specific threshold V(mmax,j). Beyond this maximal molecular volume, the adsorption vanishes due to steric exclusion. a(H,j) increases, and V(mmax,j) decreases with decreasing host pore size, in line with the confinement concept. We moreover showed that, in the limit of vanishing loading (Henry regime), the enthalpies and entropies of adsorption in a given host are linearly correlated. We have defined a host-specific confinement compensation temperature a(j), which refers to a temperature where the stabilizing adsorption enthalpic interactions are canceled out against the loss in entropy. However, calculated a(j) are much larger than the operating temperatures. With a setup microkinetic model, we predict that the activity and selectivity of the confined Ti-catalyst in ethylene oligomerization can be significantly altered with respect to homogeneous phase conditions, since the adsorption free energies of transition states and intermediates also become functions of a(H,j) and V(m). We have applied this theory to predict the optimum host pore size to get maximum α-octene production, instead of α-hexene, which is primarily produced in the homogeneous phase. We also predict a

  15. New organo-Lewis acids. Tris({beta}-perfluoronaphthyl)borane (PNB) as a highly active cocatalyst for metallocene-mediated Ziegler-Natta {alpha}-olefin polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Li, L.; Marks, T.J. [Northwestern Univ., Evanston, IL (United States). Dept. of Chemistry

    1998-08-31

    Tris({beta}-perfluoronaphthyl)borane (B(C{sub 10}F{sub 7}){sub 3}, PNB) is synthesized from {beta}-perfluoronaphthyllithium and BCl{sub 3} to serve as a new strong organo-Lewis acid cocatalyst. PNB efficiently activates a variety of group 4 dimethyl complexes to form highly active homogeneous Ziegler-Natta olefin polymerization catalysts. Reaction of PNB with rac-Me{sub 2}Si(Ind){sub 2}ZrMe{sub 2} and CGCMMe{sub 2} (M = Zr, Ti; CGC = Me{sub 2}Si({eta}{sup 5}-Me{sub 4}C{sub 5})({sup t}BuN)) (1:1 molar ratio) rapidly produces the base-free cationic complexes rac-Me{sub 2}Si(Ind){sub 2}ZrMe{sup +}MePNB{sup {minus}} (1) and CGCMMe{sup +}MePNB{sup {minus}} (M = Zr, 2; Ti, 3), respectively. The {mu}-methyl dinuclear cationic complex [(CGCTiMe){sub 2}({mu}-Me)]{sup +}MePNB{sup {minus}} (4) is formed when 2:1 CGCTiMe{sub 2}:PNB stoichiometry is employed. In the case of group 4 dimethyl zirconocenes, L{sub 2}ZrMe{sub 2} (L = {eta}{sup 5}-C{sub 5}H{sub 5}, Cp; {eta}{sup 5}-1,2-Me{sub 2}C{sub 5}H{sub 3}, Cp{double_prime}), reaction in a 1:1 metallocene:PNB ratio affords cationic complexes L{sub 2}ZrMe{sup +}MePNB{sup {minus}} (L = Cp, 5; Cp{double_prime}, 6), while the reaction with a 1:2 molar ratio affords dinuclear {mu}-methyl cationic complexes [(L{sub 2}ZrMe){sub 2}({mu}-Me)]{sup +}MePNB{sup {minus}} (L = Cp, 7; Cp{double_prime}, 8). In both reactions, {mu}-F dinuclear cationic complexes [(L{sub 2}ZrMe){sub 2}({mu}F)]{sup +}MePNB{sup {minus}} (L = Cp, 9; Cp{double_prime}, 10) are formed as byproducts. (C{sub 6}F{sub 5}){sub 3}BNCCH{sub 3} and PNBNCCH{sub 3} were synthesized and characterized.

  16. Effects of a vanadium post-metallocene catalyst-induced polymer backbone inhomogeneity on UV oxidative degradation of the resulting polyethylene film

    KAUST Repository

    Atiqullah, M.

    2012-07-01

    A Group 5 post-metallocene precatalyst, (ONO)VCl(THF) 2 (ONO = a bis(phenolate)pyridine LX 2 pincer ligand), activated with modified methylaluminoxane (MMAO-3A) produced a linear ethylene homopolymer (nm-HomoPE)and an unusual inhomogeneous copolymer (nm-CopolyPE) with 1-hexene having very low backbone unsaturation. The nm-CopolyPE inhomogeneity was reflected in the distributions of short chain branches, 1-hexene composition, and methylene sequence length. The 1-hexene incorporation into the polyethylene backbone strongly depended on the molecular weight of the growing polymer chain. (ONO)VCl(THF) 2, because of site diversity and easier removal of a tertiary (vs. a secondary) hydrogen, produced a skewed short chain branching (SCB) profile, incorporating 1-hexene more efficiently in the low molecular weight region than in the high molecular weight region. The significant decrease in molecular weight by 1-hexene showed that the (ONO)VCl(THF) 2 catalytic sites were also highly responsive to chain-transfer directly to 1-hexene itself, producing vinyl and trans-vinylene termini. Subsequently, the effect of backbone inhomogeneity on the UV oxidative degradation of films made from both polyethylenes was investigated. The major functional group accumulated in the branched nm-CopolyPE film was carbonyl followed by carboxyl, then vinyl/ester, whereas that in the linear nm-HomoPE film was carboxyl. However, (carbonyl, carboxyl, vinyl, and ester) nm-CopolyPE film >> (carboxyl) nm-HomoPE film). The distributions of the tertiary C-H sites and methylene sequence length in the branched nm-CopolyPE film enhanced abstraction of H, decomposition of hydroperoxide group ROOH, and generation of carbonyl compounds as compared with those in the linear nm-HomoPE film. This clearly establishes the role played by the backbone inhomogeneity. The effect of short chain branches and sequence length distributions on peak melting temperature T pm, and most probably lamellar thickness L o, was

  17. Introdução de catalisadores metalocênicos como estratégia competitiva da indústria de termoplásticos The introduction of metallocene catalysts as a competitive strategy of the thermoplastic industry

    Directory of Open Access Journals (Sweden)

    Francisco A. Ribeiro Fº

    1997-09-01

    Full Text Available Recentes inovações tecnológicas no setor de polímeros levaram a novos catalisadores que poderão mudar a estrutura de toda a indústria. É feita uma análise das estratégias competitivas adotadas pelas empresas do setor e do impacto que a adoção dos catalisadores metalocênicos vêm causando.Recent technological innovation in the polymer sector has produced new catalysts, which may change the structure of the industry. Competitive strategies adopted by these companies are analysed as well as the impact caused by the adoption of metallocene catalysts.

  18. Reaction-path calculations and crystal structures of 1,1'-(ethylene-1,2-diyl)dipyridinium dichloride dihydrate and 1,1'-(ethylene-1,2-diyl)dipyridinium dibromide.

    Science.gov (United States)

    Rukiah, Mwaffak; Al-Ktaifani, Mahmoud M; Sabra, Mohammad K

    2016-02-01

    The design of new organic-inorganic hybrid ionic materials is of interest for various applications, particularly in the areas of crystal engineering, supramolecular chemistry and materials science. The monohalogenated intermediates 1-(2-chloroethyl)pyridinium chloride, C5H5NCH2CH2Cl(+)·Cl(-), (I'), and 1-(2-bromoethyl)pyridinium bromide, C5H5NCH2CH2Br(+)·Br(-), (II'), and the ionic disubstituted products 1,1'-(ethylene-1,2-diyl)dipyridinium dichloride dihydrate, C12H14N2(2+)·2Cl(-)·2H2O, (I), and 1,1'-(ethylene-1,2-diyl)dipyridinium dibromide, C12H14N2(2+)·2Br(-), (II), have been isolated as powders from the reactions of pyridine with the appropriate 1,2-dihaloethanes. The monohalogenated intermediates (I') and (II') were characterized by multinuclear NMR spectroscopy, while (I) and (II) were structurally characterized using powder X-ray diffraction. Both (I) and (II) crystallize with half the empirical formula in the asymmetric unit in the triclinic space group P-1. The organic 1,1'-(ethylene-1,2-diyl)dipyridinium dications, which display approximate C2h symmetry in both structures, are situated on inversion centres. The components in (I) are linked via intermolecular O-H...Cl, C-H...Cl and C-H...O hydrogen bonds into a three-dimensional framework, while for (II), they are connected via weak intermolecular C-H...Br hydrogen bonds into one-dimensional chains in the [110] direction. The nucleophilic substitution reactions of 1,2-dichloroethane and 1,2-dibromoethane with pyridine have been investigated by ab initio quantum chemical calculations using the 6-31G** basis. In both cases, the reactions occur in two exothermic stages involving consecutive SN2 nucleophilic substitutions. The isolation of the monosubstituted intermediate in each case is strong evidence that the second step is not fast relative to the first.

  19. Arrested disproportionation in trivalent, mononuclear, and non-metallocene complexes of Zr(iii) and Hf(iii).

    Science.gov (United States)

    Grant, Lauren N; Miehlich, Matthias E; Meyer, Karsten; Mindiola, Daniel J

    2018-02-20

    Reduction of the group 4 transition metal precursors [(PN) 2 MCl 2 ] (M = Zr (1), and Hf (2)); PN - = (N-(2-(diisopropylphosphino)-4-methylphenyl)-2,4,6-trimethylanilide), both readily prepared by transmetallation of 2 LiPN with [MCl 4 (THF) 2 ], with a slight excess of KC 8 , resulted in the isolation of the trivalent complexes [(PN) 2 MCl] (M = Zr (3), and Hf (4)). Complexes 1-4 were all identified by solid-state X-ray diffraction analysis, whereas in the case of 3 and 4 low temperature X-band EPR spectroscopy allowed for the identification of these metal-centered d 1 radicals. A comparison with the isostructural and isoelectronic but more stable [(PN) 2 TiCl] is also presented.

  20. Coordination and reductive chemistry of tetraphenylborate complexes of trivalent rare earth metallocene cations, [(C5Me5)2Ln][(μ-Ph)2BPh2].

    Science.gov (United States)

    MacDonald, Matthew R; Ziller, Joseph W; Evans, William J

    2011-05-02

    The reactivity of the tetraphenylborate salts of the rare earth metallocene cations [(C(5)Me(5))(2)Ln][(μ-Ph)(2)BPh(2)] (Ln = Y, 1; Sm, 2) has been investigated with substrates that undergo reduction with f element complexes to probe metal-substrate interactions prior to reduction. Results with NaN(3), 1-adamantyl azide, acetone, benzophenone, phenanthroline, pyridine, azobenzene, and phenazine are described. Not only were coordination complexes isolated, but substrate reduction by (BPh(4))(-) was also observed. Complex 1 reacts with NaN(3) to form the azide [(C(5)Me(5))(2)YN(3)](x), 3, which crystallizes as [(C(5)Me(5))(2)Y(μ-N(3))](3), 4, when obtained from 1 and 1-adamantyl azide. The samarium analogue [(C(5)Me(5))(2)SmN(3)](x), 5, can be produced similarly from 2 and NaN(3) and crystallized from MeCN as [(C(5)Me(5))(2)Sm(NCMe)(μ-N(3))](3), 6, and {[(C(5)Me(5))(2)Sm(μ-N(3))][(C(5)Me(5))(2)Sm(NCMe)(μ-N(3))]}(n), 7. Complexes 1 and 2 react with stoichiometric amounts of acetone and benzophenone to form the ketone adducts [(C(5)Me(5))(2)Ln(OCMe(2))(2)][BPh(4)] (Ln = Y, 8; Sm, 9) and [(C(5)Me(5))(2)Ln(OCPh(2))(2)][BPh(4)] (Ln = Y, 10; Sm, 11), respectively. Phenanthroline (phen) coordinates to 1 to form [(C(5)Me(5))(2)Y(phen)][BPh(4)], 12. Complexes 1 and 2 react with pyridine (py) to form [(C(5)Me(5))(2)Ln(py)(2)][BPh(4)], (Ln = Y, 13; Sm, 14). Complexes 3, 8, 10, and 12 can also be made from the solvated cation [(C(5)Me(5))(2)Y(THF)(2)][BPh(4)]. The reaction of 1 with PhNNPh yields the diamagnetic adduct [(C(5)Me(5))(2)Y(PhNNPh)][BPh(4)], 15, which transforms in benzene to the radical anion complex (C(5)Me(5))(2)Y(PhNNPh), 16, via a one electron reduction by (BPh(4))(-). Complex 1 similarly reacts with phenazine (phz) to produce the first rare earth phenazine radical anion complex {[(C(5)Me(5))(2)Y](2)(phz)}{BPh(4)}, 17. Further reduction of phenazine by (BPh(4))(-) in 17 yields [(C(5)Me(5))(2)Y](2)(phz), 18, which contains the common (phz)(2-) dianion. The

  1. 77 FR 47539 - Paraquat Dichloride; Pesticide Tolerances

    Science.gov (United States)

    2012-08-09

    ... valid basis to show what percentage of the food derived from such crop is likely to contain the... percentage of the food treated is not likely to be an underestimation. As to Conditions b and c, regional...'' (coagulation using alum with either lime or soda ash, flocculation and sedimentation), followed by duel media...

  2. Carbosilane Metallodendrimers with Titanocene Dichloride end Groups

    Czech Academy of Sciences Publication Activity Database

    Strašák, Tomáš; Čermák, Jan; Sýkora, Jan; Horský, Jiří; Walterová, Zuzana; Jaroschik, F.; Harakat, D.

    2012-01-01

    Roč. 31, č. 19 (2012), s. 6779-6786 ISSN 0276-7333 R&D Projects: GA MŠk(CZ) LC06070 Institutional support: RVO:67985858 ; RVO:61389013 Keywords : dendrimers * titanocene * hydrosilylation Subject RIV: CC - Organic Chemistry Impact factor: 4.145, year: 2012

  3. Tetrakis(4-chloroanilinium hexachloridostannate(IV dichloride

    Directory of Open Access Journals (Sweden)

    Benhua Zhou

    2012-06-01

    Full Text Available The asymmetric unit of the title compound, (C6H7ClN4[SnCl6]Cl2, comprises two 4-chloroanilinium cations, half of an [SnCl6]2− anion and a Cl− anion. The SnIV atom, located on a special position on a twofold rotation axis, exhibits an octahedral environment. In the crystal, molecules are linked by N—H...Cl hydrogen bonds between the 4-chloroanilinium cations, [SnCl6]2− anions and Cl− anions.

  4. Scandium Cluster and Metallocene Chemistry

    OpenAIRE

    Demir, Selvan

    2010-01-01

    This thesis focuses on the synthesis and characterization of scandium compounds. One goal was to investigate the solution reactivity of {CSc6}I12Sc, which resulted in the isolation of a molecular scandium nitride, [(C5H5)2ScNSc(C5H5)(THF)]2, and a scandium propoxide complex, [(C5H5)2Sc(µ-OPr)]2. Besides this, priority was given to the synthesis and characterization of the first scandium dinitrogen complex, [(C5Me4H)2Sc]2(µ-η2:η2-N2), along with its precursor compounds: (C5Me4H)2ScCl(THF), (C5...

  5. Biochemistry of metallocenes. Pt. 3

    International Nuclear Information System (INIS)

    Wenzel, M.; Klose, W.

    1977-01-01

    103 Ru labelled 1-Ruthenocenyl-3-phenyl-propen-1-one was administered to mice intropertioneally. The organ distribution was determined in liver, spleen, lung, muscle, blood, kidney and thymus. The highest concentration was found in the thymus-up to 22% of the injected dose/g with corresponding thymus to muscle ration of up to 364 : 1. The consequences for nuclear medicine are discussed. (orig.) [de

  6. Muon implantation of metallocenes: ferrocene.

    Science.gov (United States)

    Jayasooriya, Upali A; Grinter, Roger; Hubbard, Penny L; Aston, Georgina M; Stride, John A; Hopkins, Gareth A; Camus, Laure; Reid, Ivan D; Cottrell, Stephen P; Cox, Stephen F J

    2007-01-01

    Muon Spin Relaxation and Avoided Level Crossing (ALC) measurements of ferrocene are reported. The main features observed are five high field resonances in the ALC spectrum at about 3.26, 2.44, 2.04, 1.19 and 1.17 T, for the low-temperature phase at 18 K. The high-temperature phase at 295 K shows that only the last feature shifted down to about 0.49 T and a muon spin relaxation peak at about 0.106 T which approaches zero field when reaching the phase transition temperature of 164 K. A model involving three muoniated radicals, two with muonium addition to the cyclopentadienyl ring and the other to the metal atom, is postulated to rationalise these observations. A theoretical treatment involving spin-orbit coupling is found to be required to understand the Fe-Mu adduct, where an interesting interplay between the ferrocene ring dynamics and the spin-orbit coupling of the unpaired electron is shown to be important. The limiting temperature above which the full effect of spin-orbit interaction is observable in the muSR spectra of ferrocene was estimated to be 584 K. Correlation time for the ring rotation dynamics of the Fe-Mu radical at this temperature is 3.2 ps. Estimated electron g values and the changes in zero-field splittings for this temperature range are also reported.

  7. Cationic metallocene polymerization catalysts based on tetrakis(pentafluorophenyl)borate and its derivatives. Probing the limits of anion `noncoordination` via a synthetic, solution dynamic, structural, and catalytic olefin polymerization study

    Energy Technology Data Exchange (ETDEWEB)

    Jia, L.; Yang, X.; Stern, C.L.; Marks, T.J. [Northwestern Univ., Evanston, IL (United States)

    1997-03-04

    The silyl-functionalized/protected derivatives of the tetrakis(perfluoroaryl)borate anions, B(C{sub 6}F{sub 4}TBS){sub 4}{sup -} and B(C{sub 6}F{sub 4}TIPS){sub 4}{sup -} (TBS = tert-butyldimethylsilyl and TIPS = triisopropylsilyl) have been synthesized, and a series of stable, highly reactive Zr and Th ion-paired methyl and hydride catalysts have been isolated using these anions. In contrast, the analogous B(C{sub 6}F{sub 5}){sub 4}{sup -}-based zirconocene methyl complexes are not stable at room temperature; however, B(C{sub 6}F{sub 5}){sub 4}{sup -}-based zirconocene hydride complexes can be isolated. The relative coordinative ability of the series of fluoroarylborates with respect to metallocene cations has been evaluated on the basis of spectroscopic and reactivity data. The polymerization activity of the zirconocene catalysts reaches a maximum when B(C{sub 6}F{sub 4}TBS){sub 4}{sup -} and B(C{sub 6}F{sub 4}TIPS){sub 4}{sup -} are counteranions, and the polymerization activity of the Zr constrained geometry catalyst reaches a maximum in aromatic solvents due to arene coordination when B(C{sub 6}F{sub 5}){sub 4}{sup -} is the counteranion. 37 refs., 5 figs., 7 tabs.

  8. Synthesis and reactions of (η5-C5Me4-2-C5H4N)2UCl2 and its derivatives, including the puzzling formation of the ansa-metallocene C2H4(η5-C5Me3-2-C5H4N)2UCl2

    International Nuclear Information System (INIS)

    Moisan, L.; Le Borgne, Th.; Villiers, C.; Thuery, P.; Ephritikhine, M.

    2007-01-01

    Reaction of UCl 4 with Li(C 5 Me 4 -2-C 5 H 4 N) (LiCp * Py) gave (Cp * Py) 2 UCl 2 (1), which was subsequently transformed into (Cp * Py) 2 UX 2 [X = Me (2), BH 4 (3)]. Treatment of 3 with HNEt 3 BPh 4 afforded the cationic derivative [(Cp * Py) 2 U(BH 4 )][BPh 4 ]. The ansa-metallocene C 2 H 4 (η 5 -C 5 Me 3 -2-C 5 H 4 N) 2 UCl 2 (5) was unexpectedly obtained in one reaction of 2 and CuCl 2 . The crystal structures of 1 and 5 have been determined. (authors)

  9. Diastereoselective formation of calcium and ytterbium ansa-metallocenes via recombination of guaiazulene (Gaz) radical anions. Molecular structure of ansa-(η5-Gaz)2Ca(THF)2 and ansa-(η5-Gaz)2Yb(Py)2 (Gaz=1,4-dimethyl-7-isopropylazulene) complexes

    International Nuclear Information System (INIS)

    Fedyushkin, I.L.; Kurskij, Yu.A.; Balashova, T.V.; Bochkarev, M.N.; Dekhert, S.; Myule, S.; Shuman, G.

    2003-01-01

    Metallocene derivative, i.e. ansa-(η 5 -Gaz) 2 Yb(THF) 2 (1), was synthesized by reduction of quaiazulene (Gaz) with ytterbium naphthalenide in tetrahydrofuran (THF). As a result of recrystallization of 1 from pyridine (Py) compound ansa-(η 5 -Gaz) 2 Yb(Py) 2 (2) was prepared. The products were characterized by the methods of 1 H NMR, element and X-ray diffraction analyses. It was ascertained that crystals of complexes 1 and 2 contain a racemic mixture of R, R- and S,S-enantiomers. Atoms of Yb in the complexes coordinate five-member rings of Gaz ligands according to η 5 -type [ru

  10. Thoughts on identifiers

    CERN Document Server

    CERN. Geneva

    2005-01-01

    As business processes and information transactions have become an inextricably intertwined with the Web, the importance of assignment, registration, discovery, and maintenance of identifiers has increased. In spite of this, integrated frameworks for managing identifiers have been slow to emerge. Instead, identification systems arise (quite naturally) from immediate business needs without consideration for how they fit into larger information architectures. In addition, many legacy identifier systems further complicate the landscape, making it difficult for content managers to select and deploy identifier systems that meet both the business case and long term information management objectives. This presentation will outline a model for evaluating identifier applications and the functional requirements of the systems necessary to support them. The model is based on a layered analysis of the characteristics of identifier systems, including: * Functional characteristics * Technology * Policy * Business * Social T...

  11. Identifiability in stochastic models

    CERN Document Server

    1992-01-01

    The problem of identifiability is basic to all statistical methods and data analysis, occurring in such diverse areas as Reliability Theory, Survival Analysis, and Econometrics, where stochastic modeling is widely used. Mathematics dealing with identifiability per se is closely related to the so-called branch of ""characterization problems"" in Probability Theory. This book brings together relevant material on identifiability as it occurs in these diverse fields.

  12. Identifying Knowledge and Communication

    Directory of Open Access Journals (Sweden)

    Eduardo Coutinho Lourenço de Lima

    2006-12-01

    Full Text Available In this paper, I discuss how the principle of identifying knowledge which Strawson advances in ‘Singular Terms and Predication’ (1961, and in ‘Identifying Reference and Truth-Values’ (1964 turns out to constrain communication. The principle states that a speaker’s use of a referring expression should invoke identifying knowledge on the part of the hearer, if the hearer is to understand what the speaker is saying, and also that, in so referring, speakers are attentive to hearers’ epistemic states. In contrasting it with Russell’s Principle (Evans 1982, as well as with the principle of identifying descriptions (Donnellan 1970, I try to show that the principle of identifying knowledge, ultimately a condition for understanding, makes sense only in a situation of conversation. This allows me to conclude that the cooperative feature of communication (Grice 1975 and reference (Clark andWilkes-Gibbs 1986 holds also at the understanding level. Finally, I discuss where Strawson’s views seem to be unsatisfactory, and suggest how they might be improved.

  13. Identifying learning styles.

    Science.gov (United States)

    Hughes, Grace

    2016-12-14

    What was the nature of the CPD activity, practice-related feedback and/or event and/or experience in your practice? The article explored different learning styles and outlined some of the models that can be used to identify them. It discussed the limitations of these models, indicating that although they can be helpful in identifying a student's preferred learning style, this is not 'fixed' and might change over time. Learning is also influenced by other factors, such as culture and age.

  14. spatially identifying vulnerable areas

    African Journals Online (AJOL)

    System (SMDSS) to identify factors that make forest and game reserves vulnerable to rampant human induced ... Commission Act, 1999 (Act 571); and Wildlife Resources (Amendment) (Declaration of Game Reserves). Regulations, 1976 ..... A dynamic simulation model of land-use changes in Sudano-sahelian countries of ...

  15. Identifying and Managing Risk.

    Science.gov (United States)

    Abraham, Janice M.

    1999-01-01

    The role of the college or university chief financial officer in institutional risk management is (1) to identify risk (physical, casualty, fiscal, business, reputational, workplace safety, legal liability, employment practices, general liability), (2) to develop a campus plan to reduce and control risk, (3) to transfer risk, and (4) to track and…

  16. Global Microbial Identifier

    DEFF Research Database (Denmark)

    Wielinga, Peter; Hendriksen, Rene S.; Aarestrup, Frank Møller

    2017-01-01

    -source systems. There is therefore an obvious need to develop a global system of whole microbial genome databases to aggregate, share, mine and use microbiological genomic data, to address global public health and clinical challenges, and most importantly to identify and diagnose infectious diseases. The global...... of microorganisms, for the identification of relevant genes and for the comparison of genomes to detect outbreaks and emerging pathogens. To harness the full potential of WGS, a shared global database of genomes linked to relevant metadata and the necessary software tools needs to be generated, hence the global...... microbial identifier (GMI) initiative. This tool will ideally be used in amongst others in the diagnosis of infectious diseases in humans and animals, in the identification of microorganisms in food and environment, and to track and trace microbial agents in all arenas globally. This will require...

  17. Identifying anterior segment crystals.

    OpenAIRE

    Hurley, I W; Brooks, A M; Reinehr, D P; Grant, G B; Gillies, W E

    1991-01-01

    A series of 22 patients with crystals in the anterior segment of the eye was examined by specular microscopy. Of 10 patients with hypermature cataract and hyperrefringent bodies in the anterior chamber cholesterol crystals were identified in four patients and in six of the 10 in whom aspirate was obtained cholesterol crystals were demonstrated in three, two of these having shown crystals on specular microscopy. In 10 patients with intracorneal crystalline deposits, cholesterol crystals were f...

  18. Encrypting personal identifiers.

    OpenAIRE

    Meux, E

    1994-01-01

    STUDY SETTING. A statewide patient discharge database contained only one unique identifier: the social security number (SSN). A method was developed to transform (encrypt) the SSN so that it could be made publicly available, for purposes of linking discharge records, without revealing the SSN itself. The method of encrypting the SSN into a Record Linkage Number (RLN) is described. PRINCIPAL FINDINGS. The same RLN will always result from the same SSN; it is highly improbable that the same RLN ...

  19. On identified predictive control

    Science.gov (United States)

    Bialasiewicz, Jan T.

    1993-01-01

    Self-tuning control algorithms are potential successors to manually tuned PID controllers traditionally used in process control applications. A very attractive design method for self-tuning controllers, which has been developed over recent years, is the long-range predictive control (LRPC). The success of LRPC is due to its effectiveness with plants of unknown order and dead-time which may be simultaneously nonminimum phase and unstable or have multiple lightly damped poles (as in the case of flexible structures or flexible robot arms). LRPC is a receding horizon strategy and can be, in general terms, summarized as follows. Using assumed long-range (or multi-step) cost function the optimal control law is found in terms of unknown parameters of the predictor model of the process, current input-output sequence, and future reference signal sequence. The common approach is to assume that the input-output process model is known or separately identified and then to find the parameters of the predictor model. Once these are known, the optimal control law determines control signal at the current time t which is applied at the process input and the whole procedure is repeated at the next time instant. Most of the recent research in this field is apparently centered around the LRPC formulation developed by Clarke et al., known as generalized predictive control (GPC). GPC uses ARIMAX/CARIMA model of the process in its input-output formulation. In this paper, the GPC formulation is used but the process predictor model is derived from the state space formulation of the ARIMAX model and is directly identified over the receding horizon, i.e., using current input-output sequence. The underlying technique in the design of identified predictive control (IPC) algorithm is the identification algorithm of observer/Kalman filter Markov parameters developed by Juang et al. at NASA Langley Research Center and successfully applied to identification of flexible structures.

  20. Identifying phenomenal consciousness.

    Science.gov (United States)

    Schier, Elizabeth

    2009-03-01

    This paper examines the possibility of finding evidence that phenomenal consciousness is independent of access. The suggestion reviewed is that we should look for isomorphisms between phenomenal and neural activation spaces. It is argued that the fact that phenomenal spaces are mapped via verbal report is no problem for this methodology. The fact that activation and phenomenal space are mapped via different means does not mean that they cannot be identified. The paper finishes by examining how data addressing this theoretical question could be obtained.

  1. Random Cell Identifiers Assignment

    Directory of Open Access Journals (Sweden)

    Robert Bestak

    2012-01-01

    Full Text Available Despite integration of advanced functions that enable Femto Access Points (FAPs to be deployed in a plug-and-play manner, the femtocell concept still cause several opened issues to be resolved. One of them represents an assignment of Physical Cell Identifiers (PCIs to FAPs. This paper analyses a random based assignment algorithm in LTE systems operating in diverse femtocell scenarios. The performance of the algorithm is evaluated by comparing the number of confusions for various femtocell densities, PCI ranges and knowledge of vicinity. Simulation results show that better knowledge of vicinity can significantly reduce the number of confusions events.

  2. Reaction of tin(iv) phthalocyanine dichloride with decamethylmetallocenes (M = CrII and CoII). Strong magnetic coupling of spins in (Cp*2Co+){SnIVCl2(Pc˙3-)}˙-·2C6H4Cl2.

    Science.gov (United States)

    Konarev, Dmitri V; Troyanov, Sergey I; Shestakov, Alexander F; Yudanova, Evgeniya I; Otsuka, Akihiro; Yamochi, Hideki; Kitagawa, Hiroshi; Lyubovskaya, Rimma N

    2018-01-23

    The reaction of tin(iv) phthalocyanine dichloride {Sn IV Cl 2 (Pc 2- )} with decamethylmetallocenes (Cp* 2 M, M = Co, Cr) has been studied. Decamethylcobaltocene reduces Sn IV Cl 2 (Pc 2- ) to form the (Cp* 2 Co + ){Sn IV Cl 2 (Pc˙ 3- )}˙ - ·2C 6 H 4 Cl 2 (1) complex. The negative charge of {Sn IV Cl 2 (Pc˙ 3- )}˙ - is delocalized over the Pc macrocycle providing the alternation of the C-N(imine) bonds, the appearance of new bands in the NIR range and a strong blue shift of both the Soret and Q-bands in the spectrum of 1. The magnetic moment of 1 is equal to 1.68μ B at 300 K, indicating the contribution of one S = 1/2 spin of the Pc˙ 3- macrocycles. These macrocycles form closely packed double stacks in 1 with effective π-π interactions providing strong antiferromagnetic coupling of spins at a Weiss temperature of -80 K. Decamethylchromocene initially also reduces Sn IV Cl 2 (Pc 2- ) to form the [(Cp* 2 Cr + ){Sn VI Cl 2 (Pc˙ 3- )}˙ - complex but further reaction between the ions is observed. This reaction is accompanied by the substitution of one Cp* ligand of Cp* 2 Cr by chloride anions originating from {Sn IV Cl 2 (Pc˙ 3- )}˙ - to form the complex {(Cp*CrCl 2 )(Sn IV (μ-Cl)(Pc 2- ))}·C 6 H 4 Cl 2 (2) in which the (Cp*CrCl 2 ) and {Sn IV (Pc 2- )} species are bonded through the μ-bridged Cl - anion. According to the DFT calculations, this reaction proceeds via an intermediate [(Cp* 2 CrCl)(SnClPc)] complex.

  3. Radiograph identifying means

    International Nuclear Information System (INIS)

    Sheldon, A.D.

    1983-01-01

    A flexible character-indentable plastics embossing tape is backed by and bonded to a lead strip, not more than 0.025 inches thick, to form a tape suitable for identifying radiographs. The lead strip is itself backed by a relatively thin and flimsy plastics or fabric strip which, when removed, allows the lead plastic tape to be pressure-bonded to the surface to be radiographed. A conventional tape-embossing gun is used to indent the desired characters in succession into the lead-backed tape, without necessarily severing the lead; and then the backing strip is peeled away to expose the layer of adhesive which pressure-bonds the indented tape to the object to be radiographed. X-rays incident on the embossed tape will cause the raised characters to show up dark on the subsequently-developed film, whilst the raised side areas will show up white. Each character will thus stand out on the developed film. (author)

  4. Physical properties of superbulky lanthanide metallocenes: synthesis and extraordinary luminescence of [Eu(II)(Cp(BIG))2] (Cp(BIG) = (4-nBu-C6H4)5-cyclopentadienyl).

    Science.gov (United States)

    Harder, Sjoerd; Naglav, Dominik; Ruspic, Christian; Wickleder, Claudia; Adlung, Matthias; Hermes, Wilfried; Eul, Matthias; Pöttgen, Rainer; Rego, Daniel B; Poineau, Frederic; Czerwinski, Kenneth R; Herber, Rolfe H; Nowik, Israel

    2013-09-09

    The superbulky deca-aryleuropocene [Eu(Cp(BIG))2], Cp(BIG) = (4-nBu-C6H4)5-cyclopentadienyl, was prepared by reaction of [Eu(dmat)2(thf)2], DMAT = 2-Me2N-α-Me3Si-benzyl, with two equivalents of Cp(BIG)H. Recrystallizyation from cold hexane gave the product with a surprisingly bright and efficient orange emission (45% quantum yield). The crystal structure is isomorphic to those of [M(Cp(BIG))2] (M = Sm, Yb, Ca, Ba) and shows the typical distortions that arise from Cp(BIG)⋅⋅⋅Cp(BIG) attraction as well as excessively large displacement parameter for the heavy Eu atom (U(eq) = 0.075). In order to gain information on the true oxidation state of the central metal in superbulky metallocenes [M(Cp(BIG))2] (M = Sm, Eu, Yb), several physical analyses have been applied. Temperature-dependent magnetic susceptibility data of [Yb(Cp(BIG))2] show diamagnetism, indicating stable divalent ytterbium. Temperature-dependent (151)Eu Mössbauer effect spectroscopic examination of [Eu(Cp(BIG))2] was examined over the temperature range 93-215 K and the hyperfine and dynamical properties of the Eu(II) species are discussed in detail. The mean square amplitude of vibration of the Eu atom as a function of temperature was determined and compared to the value extracted from the single-crystal X-ray data at 203 K. The large difference in these two values was ascribed to the presence of static disorder and/or the presence of low-frequency torsional and librational modes in [Eu(Cp(BIG))2]. X-ray absorbance near edge spectroscopy (XANES) showed that all three [Ln(Cp(BIG))2] (Ln = Sm, Eu, Yb) compounds are divalent. The XANES white-line spectra are at 8.3, 7.3, and 7.8 eV, for Sm, Eu, and Yb, respectively, lower than the Ln2O3 standards. No XANES temperature dependence was found from room temperature to 100 K. XANES also showed that the [Ln(Cp(BIG))2] complexes had less trivalent impurity than a [EuI2(thf)x] standard. The complex [Eu(Cp(BIG))2] shows already at room temperature

  5. Monochloro non-bridged half-metallocene-type zirconium complexes containing phosphine oxide-(thio)phenolate chelating ligands as efficient ethylene polymerization catalysts.

    Science.gov (United States)

    Tang, Xiao-Yan; Wang, Yong-Xia; Liu, San-Rong; Liu, Jing-Yu; Li, Yue-Sheng

    2013-01-14

    A series of novel monochloro half-zirconocene complexes containing phosphine oxide-(thio)phenolate chelating ligands of the type, ClCp'Zr[X-2-R(1)-4-R(2)-6-(Ph(2)P=O)C(6)H(2)](2) (Cp' = C(5)H(5), 2a: X = O, R(1) = Ph, R(2) = H; 2b: X = O, R(1) = F, R(2) = H; 2c: X = O, R(1) = (t)Bu, R(2) = H; 2d: X = O, R(1) = R(2) = (t)Bu; 2e: X = O, R(1) = SiMe(3), R(2) = H; 2f: X = S, R(1) = SiMe(3), R(2) = H; Cp' = C(5)Me(5), 2g: X = O, R(1) = SiMe(3), R(2) = H), have been synthesized in high yields. These complexes were identified by (1)H {(13)C} NMR and elemental analyses. Structures for 2b, 2c and 2f were further confirmed by X-ray crystallography. Structural characterization of these complexes reveals crowded environments around the zirconium. Complexes 2b and 2c adopt six-coordinate, distorted octahedral geometry around the zirconium center, in which the equatorial positions are occupied by three oxygen atoms of two chelating phosphine oxide-bridged phenolate ligands and a chlorine atom. The cyclopentadienyl ring and one oxygen atom of the ligand are coordinated on the axial position. Complex 2f also folds a six-coordinate, distorted octahedral geometry around the Zr center, consisting of a Cp-Zr-O (in P=O) axis [177.16°] and a distorted plane of two sulfur atoms and one oxygen atom of two chelating phosphine oxide-bridged thiophenolate ligands as well as a chlorine atom. When activated by modified methylaluminoxane (MMAO), all the complexes exhibited high activities towards ethylene polymerization at high temperature (75 °C), giving high molecular weight polymers with unimodal molecular weight distribution. The formation of 14-electron, cationic metal alkyl species might come from the Zr-O (in phenol ring) bond cleavage based on the DFT calculations study.

  6. Electrochemical properties of metallocene hydroxo and oxo complexes of Ta(V): [Cp*(CpR)TaOHCl]{sup +}Cl{sup -}, R = H, SiMe{sub 3} or (CH{sub 2}){sub 3}NC{sub 4}H{sub 4}, Cp*(Cp(CH{sub 2}){sub 3}NC{sub 4}H{sub 4})TaOCl

    Energy Technology Data Exchange (ETDEWEB)

    Skompska, Magdalena [Department of Chemistry, Warsaw University, ul. Pasteura 1, 02093 Warsaw (Poland)], E-mail: mskomps@chem.uw.edu.pl; Vorotyntsev, Mikhail A. [ICMUB-UMR 5260 CNRS, University of Bourgogne, Bat. Mirande, 9 Avenue A. Savary, BP 47870, 21078 Dijon Cedex (France)], E-mail: mv@u-bourgogne.fr; Goux, Jerome; Le Gendre, Pierre; Moise, Claude [ICMUB-UMR 5260 CNRS, University of Bourgogne, Bat. Mirande, 9 Avenue A. Savary, BP 47870, 21078 Dijon Cedex (France)

    2008-04-20

    Redox properties of three cationic tantalocene hydroxo complexes, [Cp*(CpR)Ta{sup V}OHCl]{sup +}, with one pentamethylated cyclopentadienyl ligand, Cp* = {eta}{sup 5}-C{sub 5}Me{sub 5}, Me = CH{sub 3}, and one monosubstituted cyclopentadienyl ligand, CpR, Cp = C{sub 5}H{sub 4}, R = H, SiMe{sub 3} or (CH{sub 2}){sub 3}NC{sub 4}H{sub 4}, as well as of an oxo complex with the pyrrole-containing ligand, Cp*(Cp(CH{sub 2}){sub 3}NC{sub 4}H{sub 4})TaOCl, have been studied in acetonitrile solutions with cyclic voltammetry in the ranges of the Ta(V) reduction to Ta(IV) and to Ta(III). Both transitions are irreversible due to the dissociation of reduced complexes with the loss of their chloride ligand. The mechanism of hydroxo complex reduction is discussed in terms of its reversible deprotonation/protonation equilibrium with the corresponding oxo complex, Cp*(CpR)TaOCl. The variation of the reduction potential for the Ta(V)/Ta(IV) transition in the negative direction in the series of tantalocene complexes: dichloride > hydroxo > oxo, as well as the difference in the behavior of the reduced (Ta(IV)) complexes (stable for dichloride but losing their chloride ligand for hydroxo and oxo complexes) was explained by the increase of the electronic density at the central metal in this series, correlated with the weakening of the Ta-Cl bond and its easier dissociation. The tantalocene centers were immobilized inside a polypyrrole matrix on the electrode surface by electropolymerization of the cationic complex [Cp*(Cp(CH{sub 2}){sub 3}NC{sub 4}H{sub 4})TaOHCl]{sup +}. This was possible after removal of the 'free' chloride ions from the polymerization bath by their precipitation upon addition of TlPF{sub 6}. The corresponding polymer, poly[Cp*(Cp(CH{sub 2}){sub 3}NC{sub 4}H{sub 4})TaOHCl], was found to be electroactive in contact with a background electrolyte, giving a redox response both in the polymer matrix and tantalocene potential ranges. The mechanism of the

  7. Metallocene mit \\(CF_{3}\\)-haltigen Substituenten

    OpenAIRE

    Maschke, Marcus (M. Sc.)

    2016-01-01

    Die vorliegende Arbeit beschreibt die Untersuchung der Struktur-Wirkungsbeziehung von neuartigen Metallocenen mit \\(CF_{3}\\)-haltigen Substituenten sowie deren Biokonjugation mit ausgewählten Peptiden. Im Rahmen der Untersuchung der Struktur-Wirkungsbeziehung wurde gefunden, dass die Strukturelemente Metall, OH-Funktion und \\(CF_{3}\\)-Gruppen essentiell für die antiproliferative Wirkung der Metallkomplexe sind. Bezogen auf die physikochemischen Eigenschaften konnte gezeigt werden, dass die...

  8. Dynamic Pseudorotaxane Crystals Containing Metallocene Complexes.

    Science.gov (United States)

    Chen, Kai-Jen; Chen, Pei-Lin; Horie, Masaki

    2017-10-27

    Molecular machines and switches composed of flexible pseudorotaxanes respond to external stimuli, transducing incident energy into mechanical motions. This study presents thermo- and photoresponsive dynamic pseudorotaxane crystals composed of axle molecules containing ferrocene or ruthenocene groups threaded through dibenzo[24]crown-8 ether rings. The ruthenocene-containing pseudorotaxane exhibits a crystal-to-crystal thermal phase transition at 86 °C, which is much lower than that of the ferrocene-containing pseudorotaxane (128 °C). Single-crystal X-ray crystallography at various temperatures reveals the details of the structural changes, and shows that the bulky ruthenocene provides distortion in the pseudorotaxane structure to facilitate twisting of the axle molecule. A mixed ferrocene and ruthenocene pseudorotaxane crystal is applied to photomechanical conversion under 405 nm laser irradiation at 85 °C and provides a lifting force 6,400-times the weight of the crystal itself upon phase transition.

  9. Dynamic Pseudorotaxane Crystals Containing Metallocene Complexes

    OpenAIRE

    Chen, Kai-Jen; Chen, Pei-Lin; Horie, Masaki

    2017-01-01

    Molecular machines and switches composed of flexible pseudorotaxanes respond to external stimuli, transducing incident energy into mechanical motions. This study presents thermo- and photoresponsive dynamic pseudorotaxane crystals composed of axle molecules containing ferrocene or ruthenocene groups threaded through dibenzo[24]crown-8 ether rings. The ruthenocene-containing pseudorotaxane exhibits a crystal-to-crystal thermal phase transition at 86 °C, which is much lower than that of the fer...

  10. Phosphorus-bridged ansa-metallocene complexes of titanium, zirconium, and hafnium: The syntheses and structures of [PhP(C{sub 5}Me{sub 4}){sub 2}]MX{sub 2} and [Ph(E)P(C{sub 5}Me{sub 4}){sub 2}]MX{sub 2} (E = O, S, Se) derivatives

    Energy Technology Data Exchange (ETDEWEB)

    Shin, J.H.; Hascall, T.; Parkin, G. [Columbia Univ., New York, NY (United States). Dept. of Chemistry

    1999-01-04

    A series of phosphorus-bridged ansa-metallocene complexes of titanium, zirconium, and hafnium, [PhP(XC{sub 5}Me{sub 4}){sub 2}]MX{sub 2} and [Ph(E)P(C{sub 5}Me{sub 4}){sub 2}]MX{sub 2} (X = Cl, Me, CO, (Se{sub 3}){sub 0.5}; E = O, S, Se), has been synthesized. Structural characterization by X-ray diffraction indicates that, in comparison to their non-ansa counterparts (C{sub 5}Me{sub 5}){sub 2}MX{sub 2}, the cyclopentadienyl groups in phosphorus-bridged complexes are displaced from symmetric {eta}{sup 5}-coordination toward {eta}{sup 3}-coordination. Such {eta}{sup 3},{eta}{sup 3}-coordination creates more electrophilic metal centers than those in their permethylcyclopentadienyl counterparts, as judged by the {nu}(CO) stretching frequencies of the zirconium dicarbonyl complexes Cp{sup *}{sub 2}Zr(CO){sub 2} (1946 and 1853 cm{sup {minus}1}) and [PhP(C{sub 5}Me{sub 4}){sub 2}]Zr(CO){sub 2} (1959 and 1874 cm{sup {minus}1}).

  11. Method of deuterium isotope separation using ethylene and ethylene dichloride

    International Nuclear Information System (INIS)

    Benson, S.W.

    1982-01-01

    Compounds enriched in deuterium may be obtained from ethylene, vinyl chloride, 1,2-dichloroethane, or propylene by laser isotope separation. Normal molecules of these organic compounds are exposed to infrared laser radiation of a suitable wavelength. Substantially all of the deuterium-containing molecules exposed to the laser can be selectively dissociated and the deuterium-containing products separated from the starting material and other reaction products. The deuterium-containing molecules can be burned to form water with an enriched deuterium content, or pyrolized to form hydrogen gas enriched in deuterium

  12. bipyridinium dichloride-induced hepatic and renal toxicity in Swiss ...

    African Journals Online (AJOL)

    Purpose: To evaluate the effectiveness of vitamin C on paraquat-induced hepatic and renal toxicity in. Swiss albino mice. Methods: Three groups of Swiss albino mice (n = 10), i.e., control, paraquat (15 mg/kg) and paraquat. (15 mg/kg) + vitamin C (20 mg/kg) were used in the study. The drugs were administered.

  13. Redetermination of diaquatetrakis(dimethylformamide-κOmagnesium dichloride

    Directory of Open Access Journals (Sweden)

    Guido J. Reiss

    2011-08-01

    Full Text Available The crystal structure of the title compound, [Mg(C3H7NO4(H2O2]Cl2, in which the Mg ion lies on a crystallographic inversion centre, confirms that of the previous room-temperature study [Pavanello et al. (1995. Main Group Met. Chem. 18, 9–19]. This redetermination at 113 K has improved geometry precision by almost an order of magnitude [e.g. Mg—O(w (w = water distances = 2.094 (4 and 2.0899 (7 Å in the old and new structures, respectively] and allowed the water H atoms to be located and their positions refined. In the crystal, O—H...Cl hydrogen bonds between the two aqua ligands of the complex molecule and neighboring chloride counter-anions generate supramolecular chains propagating along [010]. The dicationic [Mg(DMF4(H2O2] unit (DMF is dimethylformamide adopts a slightly distorted octahedral geometry in which the Mg atom is coordinated by four DMF O atoms in a pseudo-tetragonal arrangement and two trans aqua ligands.

  14. New criteria to identify spectrum

    DEFF Research Database (Denmark)

    Jensen, Arne; Krishna, M.

    In this paper we give some new criteria for identifying the components of a probability measure, in its Lebesgue decomposition. This enables us to give new criteria to identify spectral types of self adjoint operators on Hilbert spaces, especially those of interest....

  15. New criteria to identify spectrum

    DEFF Research Database (Denmark)

    Jensen, Arne; Krishna, M.

    2005-01-01

    In this paper we give some new criteria for identifying the components of a probability measure, in its Lebesgue decomposition. This enables us to give new criteria to identify spectral types of self-adjoint operators on Hilbert spaces, especially those of interest....

  16. Identifying discharge practice training needs.

    Science.gov (United States)

    Lees, L; Emmerson, K

    A training needs analysis tool was developed to identify nurses' discharge training needs and to improve discharge practice. The tool includes 49 elements of discharge practice subdivided into four areas: corporate, operational, clinical and nurse-led discharge. The tool was disseminated to 15 wards on two hospital sites with assistance from the practice development team. Analysis of discharge training is important to assess discharge training needs and to identify staff who may assist with training.

  17. Identifying tier one key suppliers.

    Science.gov (United States)

    Wicks, Steve

    2013-01-01

    In today's global marketplace, businesses are becoming increasingly reliant on suppliers for the provision of key processes, activities, products and services in support of their strategic business goals. The result is that now, more than ever, the failure of a key supplier has potential to damage reputation, productivity, compliance and financial performance seriously. Yet despite this, there is no recognised standard or guidance for identifying a tier one key supplier base and, up to now, there has been little or no research on how to do so effectively. This paper outlines the key findings of a BCI-sponsored research project to investigate good practice in identifying tier one key suppliers, and suggests a scalable framework process model and risk matrix tool to help businesses effectively identify their tier one key supplier base.

  18. Sparse Linear Identifiable Multivariate Modeling

    DEFF Research Database (Denmark)

    Henao, Ricardo; Winther, Ole

    2011-01-01

    In this paper we consider sparse and identifiable linear latent variable (factor) and linear Bayesian network models for parsimonious analysis of multivariate data. We propose a computationally efficient method for joint parameter and model inference, and model comparison. It consists of a fully...... Bayesian hierarchy for sparse models using slab and spike priors (two-component δ-function and continuous mixtures), non-Gaussian latent factors and a stochastic search over the ordering of the variables. The framework, which we call SLIM (Sparse Linear Identifiable Multivariate modeling), is validated...... computational complexity. We attribute this mainly to the stochastic search strategy used, and to parsimony (sparsity and identifiability), which is an explicit part of the model. We propose two extensions to the basic i.i.d. linear framework: non-linear dependence on observed variables, called SNIM (Sparse Non-linear...

  19. Football refereeing: Identifying innovative methods

    Directory of Open Access Journals (Sweden)

    Reza MohammadKazemi

    2014-08-01

    Full Text Available The aim of the present study is to identify the potentials innovation in football industry. Data were collected from 10 national and international referees, assistant referees and referees’ supervisors in Iran. In this study, technological innovations are identified that assist better refereeing performances. The analysis revealed a significant relationship between using new technologies and referees ‘performance. The results indicate that elite referees, assistant referees and supervisors agreed to use new technological innovations during the game. According to their comments, this kind of technology causes the referees’ performance development.

  20. Testing times: identifying puberty in an identified skeletal sample.

    Science.gov (United States)

    Henderson, Charlotte Y; Padez, Cristina

    2017-06-01

    Identifying the onset of puberty in skeletal remains can provide evidence of social changes associated with the onset of adulthood. This paper presents the first test of a skeletal method for identifying stages of development associated with the onset of puberty in a skeletal sample of known age and cause of death. Skeletal methods for assessing skeletal development associated with changes associated with puberty were recorded in the identified skeletal collection in Coimbra, Portugal. Historical data on the onset of menarche in this country are used to test the method. As expected, females mature faster than their male counterparts. There is some side asymmetry in development. Menarche was found to have been achieved by an average age of 15. Asymmetry must be taken into account when dealing with partially preserved skeletons. Age of menarche is consistent, although marginally higher, than the age expected based on historical data for this time and location. Skeletal development in males could not be tested against historical data, due to the lack of counterpart historical data. The ill health known to be present in this prematurely deceased population may have delayed skeletal development and the onset of puberty.

  1. Minimal output sets for identifiability.

    Science.gov (United States)

    Anguelova, Milena; Karlsson, Johan; Jirstrand, Mats

    2012-09-01

    Ordinary differential equation models in biology often contain a large number of parameters that must be determined from measurements by parameter estimation. For a parameter estimation procedure to be successful, there must be a unique set of parameters that can have produced the measured data. This is not the case if a model is not uniquely structurally identifiable with the given set of outputs selected as measurements. In designing an experiment for the purpose of parameter estimation, given a set of feasible but resource-consuming measurements, it is useful to know which ones must be included in order to obtain an identifiable system, or whether the system is unidentifiable from the feasible measurement set. We have developed an algorithm that, from a user-provided set of variables and parameters or functions of them assumed to be measurable or known, determines all subsets that when used as outputs give a locally structurally identifiable system and are such that any output set for which the system is structurally identifiable must contain at least one of the calculated subsets. The algorithm has been implemented in Mathematica and shown to be feasible and efficient. We have successfully applied it in the analysis of large signalling pathway models from the literature. Copyright © 2012 Elsevier Inc. All rights reserved.

  2. Identifying high-risk medication

    DEFF Research Database (Denmark)

    Sædder, Eva; Brock, Birgitte; Nielsen, Lars Peter

    2014-01-01

    salicylic acid, and beta-blockers; 30 drugs or drug classes caused 82 % of all serious MEs. The top ten drugs involved in fatal events accounted for 73 % of all drugs identified. CONCLUSION: Increasing focus on seven drugs/drug classes can potentially reduce hospitalizations, extended hospitalizations...

  3. SNP interaction pattern identifier (SIPI)

    DEFF Research Database (Denmark)

    Lin, Hui Yi; Chen, Dung Tsa; Huang, Po Yu

    2017-01-01

    Motivation: Testing SNP-SNP interactions is considered as a key for overcoming bottlenecks of genetic association studies. However, related statistical methods for testing SNP-SNP interactions are underdeveloped. Results: We propose the SNP Interaction Pattern Identifier (SIPI), which tests 45 bi...

  4. Influência da estrutura do catalisador a base de Zirconoceno na estereorregularidade e propriedades do polipropileno formado Influence of Zirconocene structure on polypropylene stereorregularity and properties

    Directory of Open Access Journals (Sweden)

    Mário R. Meneghetti

    1997-03-01

    Full Text Available RESUMO: Catalisadores de metalocenos com diferentes simetrias, cocatalisados por metilaluminoxanas (MAO, foram avaliados em diferentes temperaturas de polimerização do propileno. Os metalocenos com ponte interanelar, ou seja, o dicloreto de rac-etileno bis(h5-1-indenil zircônio, com simetria C2, e o dicloreto de isopropilideno(h5-ciclopentadienil(h5-9-fluorenil zircônio, com simetria Cs, produziram, respectivamente, polipropileno isotático e sindiotático. O grau de taticidade desses polímeros diminui com o aumento da temperatura de polimerização. Os metalocenos sem ponte, dicloreto de bis(h5-ciclopentadienilzircônio e bis(h5-indenilzircônio, em qualquer uma das temperaturas investigadas, produziram, somente, polipropileno atático. A estereorregularidade dos polímeros foram determinadas por Ressonância Magnética Nuclear de 13C.ABSTRACT: Metallocenes with different symmetries in combination with methylaluminoxane (MAO, have been investigated at different propylene polymerization temperatures. The metallocenes rac-ethylene bis(h5-1-indenyl zirconium dichloride, with C2 symmetry and isopropylidene (h5cyclopentadienyl(h5-9-fluorenyl zirconium dichloride, with Cs symmetry, produce isotactic and syndiotactic polypropylene respectively. The degree of tacticity of these polymers decreases with the increase of polymerization temperature. Only atactic polypropylene was formed with the unbridged zirconocenes bis(h5-cyclopentadienyl zirconium dichloride and bis(h5-indenyl zirconium dichloride at any temperature investigated. The polymer microtacticity was analysed by 13C NMR.

  5. Distributed Persistent Identifiers System Design

    Directory of Open Access Journals (Sweden)

    Pavel Golodoniuc

    2017-06-01

    Full Text Available The need to identify both digital and physical objects is ubiquitous in our society. Past and present persistent identifier (PID systems, of which there is a great variety in terms of technical and social implementation, have evolved with the advent of the Internet, which has allowed for globally unique and globally resolvable identifiers. PID systems have, by in large, catered for identifier uniqueness, integrity, and persistence, regardless of the identifier’s application domain. Trustworthiness of these systems has been measured by the criteria first defined by Bütikofer (2009 and further elaborated by Golodoniuc 'et al'. (2016 and Car 'et al'. (2017. Since many PID systems have been largely conceived and developed by a single organisation they faced challenges for widespread adoption and, most importantly, the ability to survive change of technology. We believe that a cause of PID systems that were once successful fading away is the centralisation of support infrastructure – both organisational and computing and data storage systems. In this paper, we propose a PID system design that implements the pillars of a trustworthy system – ensuring identifiers’ independence of any particular technology or organisation, implementation of core PID system functions, separation from data delivery, and enabling the system to adapt for future change. We propose decentralisation at all levels — persistent identifiers and information objects registration, resolution, and data delivery — using Distributed Hash Tables and traditional peer-to-peer networks with information replication and caching mechanisms, thus eliminating the need for a central PID data store. This will increase overall system fault tolerance thus ensuring its trustworthiness. We also discuss important aspects of the distributed system’s governance, such as the notion of the authoritative source and data integrity

  6. Chemistry of trivalent uranium metallocenes: electron-transfer reactions. Synthesis and characterization of [(MeC5H4)3U]2E (E = S, Se, Te) and the crystal structures of [(MeC5H4)3U]2S and (MeC5H4)3UOPPh3

    International Nuclear Information System (INIS)

    Brennan, J.G.; Andersen, R.A.; Zalkin, A.

    1986-01-01

    The trivalent uranium metallocene (MeC 5 H 4 ) 3 U x THF reacts with COS, SPPh 3 , or TeP(n-Bu) 3 to form the bridging chalcogenide complexes [(MeC 5 H 4 ) 3 U] 2 E, where E is S, Se, or Te. Crystals of [(MeC 5 H 4 ) 3 U] 2 S are monoclinic, P2 1 /c, with a = 19.740 (6) A, b = 8.302 (3) A, c = 21.602(4) A, and β = 97.28 (3) 0 at 23 0 C; for Z = 4 the calculated density is 1.920 g/cm 3 . The structure was refined by full-matrix least squares to a conventional R factor of 0.053 by using 2061 data with F 2 > 2 sigma (F 2 ). The average U-C distance is 2.77 +/- 0.06 A, the U-S distance is 2.60 (1) A, and the U-S-U angle is 164.9 (5) 0 . Triphenylphosphine oxide does not behave in a similar fashion; the trivalent uranium coordination complex (MeC 5 H 4 ) 3 UOPPh 3 is instead isolated. Crystals of (MeC 5 H 4 ) 3 UOPPh 3 are monoclinic, P2 1 /n, with a = 16.268 (3) A, b = 17.948 (3) A, c = 10.900 (2) A, and β = 105.01 (2) 0 at 23 0 C; for Z = 4 the calculated density is 1.628 g/cm 3 . The structure was refined by full-matrix least squares to a conventional R factor of 0.028 [2427 data, F 2 > 2 sigma (F 2 )]. The average U-C distance is 2.82 +/- 0.04 A, the U-O distance is 2.389 (6) A, and the U-O-P angle is 162.8 (4) 0

  7. ORCID: Author Identifiers for Librarians

    Directory of Open Access Journals (Sweden)

    Robyn B. Reed

    2017-10-01

    Full Text Available Generating accurate publication lists by researchers can be challenging when faced with scholars who have common names or who have published under name variations. This article describes ORCID and the goal of generating author identifiers for scholars to connect their research outputs. Included are the reasons for having author identifiers as well as the types of information within individual profiles. This article includes information on how academic libraries are playing a role with ORCID initiatives as well as describing how publishers, institutions, and funders are employing ORCID in their workflows. Highlighted is material on academic institutions in Pennsylvania using ORCID. The purpose of the article is to provide an overview of ORCID and its uses to inform librarians about this important initiative.

  8. Identifying patient risks during hospitalization

    Directory of Open Access Journals (Sweden)

    Lucélia Ferreira Lima

    2008-12-01

    Full Text Available Objective: To identify the risks reported at a public institution andto know the main patient risks from the nursing staff point of view.Methods: A retrospective, descriptive and exploratory study. Thesurvey was developed at a hospital in the city of Taboão da Serra, SãoPaulo, Brazil. The study included all nurses working in care areas whoagreed to participate in the study. At the same time, sentinel eventsoccurring in the period from July 2006 to July 2007 were identified.Results: There were 440 sentinel events reported, and the main risksincluded patient falls, medication errors and pressure ulcers. Sixty-fivenurses were interviewed. They also reported patient falls, medicationerrors and pressure ulcers as the main risks. Conclusions: Riskassessment and implementation of effective preventive actions arenecessary to ensure patient’s safety. Involvement of a multidisciplinaryteam is one of the steps for a successful process.

  9. Identifying vertex covers in graphs

    DEFF Research Database (Denmark)

    Henning, Michael A.; Yeo, Anders

    2012-01-01

    An identifying vertex cover in a graph G is a subset T of vertices in G that has a nonempty intersection with every edge of G such that T distinguishes the edges, that is, e∩T ≠ 0 for every edge e in G and e∩T ≠ f∩T for every two distinct edges e and f in G. The identifying vertex cover number TD......(G) of G is the minimum size of an identifying vertex cover in G. We observe that TD(G)+ρ(G) = |V (G)|, where ρ(G) denotes the packing number of G. We conjecture that if G is a graph of order n and size m with maximum degree Δ, then TD(G) ≤(Δ(Δ-1)/ Δ2+1)n + (2/Δ2+1) m. If the conjecture is true......, then the bound is best possible for all Δ ≥ 1. We prove this conjecture when Δ ≥ 1 and G is a Δ-regular graph. The three known Moore graphs of diameter 2, namely the 5-cycle, the Petersen graph and the Hoffman-Singleton graph, are examples of regular graphs that achieves equality in the upper bound. We also...

  10. Identifying flares in rheumatoid arthritis

    DEFF Research Database (Denmark)

    Bykerk, Vivian P; Bingham, Clifton O; Choy, Ernest H

    2016-01-01

    to flare, with escalation planned in 61%. CONCLUSIONS: Flares are common in rheumatoid arthritis (RA) and are often preceded by treatment reductions. Patient/MD/DAS agreement of flare status is highest in patients worsening from R/LDA. OMERACT RA flare questions can discriminate between patients with...... Set. METHODS: Candidate flare questions and legacy measures were administered at consecutive visits to Canadian Early Arthritis Cohort (CATCH) patients between November 2011 and November 2014. The American College of Rheumatology (ACR) core set indicators were recorded. Concordance to identify flares...

  11. IDENTIFYING BEST PRACTICES IN INSURANCE

    Directory of Open Access Journals (Sweden)

    Răducu Marian PETRESCU

    2016-05-01

    Full Text Available This work aims to identify and develop best practices in the insurance field. We must mention from the beginning that best practices are not compulsory or mandatory rules of law, they cannot and do not want to be placed above the legal provisions in force, they only complement the law. Moreover, we intend to look into the implementation of the Solvency II Directive from the point of view of best practices in insurance. In this research, the main method of study was the theoretical qualitative research (especially document analysis, with the purpose to identify and theoretically develop the information on best practices in the insurance field. The main results of the research consist in the identification of general best practices in performing the activity (such as communication/consultation with the interested parties, the consistency as regards contractual/non-contractual relations, the effectiveness and efficiency, transparency and honesty, fair treatment of customers etc. which have been presented in short and which could be implemented by any company that seeks to achieve superior performances, including the insurance companies. The work also includes some important best practices, described in detail, in a sensitive area such as the insurance field (best practices in relation to the management of personal information, the management and settlement of disputes by insurance companies or intermediaries in the field of insurance etc..

  12. Featured Image: Identifying Weird Galaxies

    Science.gov (United States)

    Kohler, Susanna

    2017-08-01

    Hoags Object, an example of a ring galaxy. [NASA/Hubble Heritage Team/Ray A. Lucas (STScI/AURA)]The above image (click for the full view) shows PanSTARRSobservationsof some of the 185 galaxies identified in a recent study as ring galaxies bizarre and rare irregular galaxies that exhibit stars and gas in a ring around a central nucleus. Ring galaxies could be formed in a number of ways; one theory is that some might form in a galaxy collision when a smaller galaxy punches through the center of a larger one, triggering star formation around the center. In a recent study, Ian Timmis and Lior Shamir of Lawrence Technological University in Michigan explore ways that we may be able to identify ring galaxies in the overwhelming number of images expected from large upcoming surveys. They develop a computer analysis method that automatically finds ring galaxy candidates based on their visual appearance, and they test their approach on the 3 million galaxy images from the first PanSTARRS data release. To see more of the remarkable galaxies the authors found and to learn more about their identification method, check out the paper below.CitationIan Timmis and Lior Shamir 2017 ApJS 231 2. doi:10.3847/1538-4365/aa78a3

  13. Persistent Identifiers as Boundary Objects

    Science.gov (United States)

    Parsons, M. A.; Fox, P. A.

    2017-12-01

    In 1989, Leigh Star and Jim Griesemer defined the seminal concept of `boundary objects'. These `objects' are what Latour calls `immutable mobiles' that enable communication and collaboration across difference by helping meaning to be understood in different contexts. As Star notes, they are a sort of arrangement that allow different groups to work together without (a priori) consensus. Part of the idea is to recognize and allow for the `interpretive flexibility' that is central to much of the `constructivist' approach in the sociology of science. Persistent Identifiers (PIDs) can clearly act as boundary objects, but people do not usually assume that they enable interpretive flexibility. After all, they are meant to be unambiguous, machine-interpretable identifiers of defined artifacts. In this paper, we argue that PIDs can fill at least two roles: 1) That of the standardized form, where there is strong agreement on what is being represented and how and 2) that of the idealized type, a more conceptual concept that allows many different representations. We further argue that these seemingly abstract conceptions actually help us implement PIDs more effectively to link data, publications, various other artifacts, and especially people. Considering PIDs as boundary objects can help us address issues such as what level of granularity is necessary for PIDs, what metadata should be directly associated with PIDs, and what purpose is the PID serving (reference, provenance, credit, etc.). In short, sociological theory can improve data sharing standards and their implementation in a way that enables broad interdisciplinary data sharing and reuse. We will illustrate this with several specific examples of Earth science data.

  14. Identifying and Tracing User Needs

    Science.gov (United States)

    To, C.; Tauer, E.

    2017-12-01

    Providing adequate tools to the user community hinges on reaching the specific goals and needs behind the intended application of the tool. While the approach of leveraging user-supplied inputs and use cases to identify those goals is not new, there frequently remains the challenge of tracing those use cases through to implementation in an efficient and manageable fashion. Processes can become overcomplicated very quickly, and additionally, explicitly mapping progress towards the achievement of the user demands can become overwhelming when hundreds of use-cases are at play. This presentation will discuss a demonstrated use-case approach that has achieved an initial success with a tool re-design and deployment, the means to apply use cases in the generation of a roadmap for future releases over time, and the ability to include and adjust to new user requirements and suggestions with minimal disruption to the traceability. It is hoped that the findings and lessons learned will help make use case employment easier for others seeking to create user-targeted capabilities.

  15. RECOVIR Software for Identifying Viruses

    Science.gov (United States)

    Chakravarty, Sugoto; Fox, George E.; Zhu, Dianhui

    2013-01-01

    Most single-stranded RNA (ssRNA) viruses mutate rapidly to generate a large number of strains with highly divergent capsid sequences. Determining the capsid residues or nucleotides that uniquely characterize these strains is critical in understanding the strain diversity of these viruses. RECOVIR (an acronym for "recognize viruses") software predicts the strains of some ssRNA viruses from their limited sequence data. Novel phylogenetic-tree-based databases of protein or nucleic acid residues that uniquely characterize these virus strains are created. Strains of input virus sequences (partial or complete) are predicted through residue-wise comparisons with the databases. RECOVIR uses unique characterizing residues to identify automatically strains of partial or complete capsid sequences of picorna and caliciviruses, two of the most highly diverse ssRNA virus families. Partition-wise comparisons of the database residues with the corresponding residues of more than 300 complete and partial sequences of these viruses resulted in correct strain identification for all of these sequences. This study shows the feasibility of creating databases of hitherto unknown residues uniquely characterizing the capsid sequences of two of the most highly divergent ssRNA virus families. These databases enable automated strain identification from partial or complete capsid sequences of these human and animal pathogens.

  16. Identifying ELIXIR Core Data Resources.

    Science.gov (United States)

    Durinx, Christine; McEntyre, Jo; Appel, Ron; Apweiler, Rolf; Barlow, Mary; Blomberg, Niklas; Cook, Chuck; Gasteiger, Elisabeth; Kim, Jee-Hyub; Lopez, Rodrigo; Redaschi, Nicole; Stockinger, Heinz; Teixeira, Daniel; Valencia, Alfonso

    2016-01-01

    The core mission of ELIXIR is to build a stable and sustainable infrastructure for biological information across Europe. At the heart of this are the data resources, tools and services that ELIXIR offers to the life-sciences community, providing stable and sustainable access to biological data. ELIXIR aims to ensure that these resources are available long-term and that the life-cycles of these resources are managed such that they support the scientific needs of the life-sciences, including biological research. ELIXIR Core Data Resources are defined as a set of European data resources that are of fundamental importance to the wider life-science community and the long-term preservation of biological data. They are complete collections of generic value to life-science, are considered an authority in their field with respect to one or more characteristics, and show high levels of scientific quality and service. Thus, ELIXIR Core Data Resources are of wide applicability and usage. This paper describes the structures, governance and processes that support the identification and evaluation of ELIXIR Core Data Resources. It identifies key indicators which reflect the essence of the definition of an ELIXIR Core Data Resource and support the promotion of excellence in resource development and operation. It describes the specific indicators in more detail and explains their application within ELIXIR's sustainability strategy and science policy actions, and in capacity building, life-cycle management and technical actions. The identification process is currently being implemented and tested for the first time. The findings and outcome will be evaluated by the ELIXIR Scientific Advisory Board in March 2017. Establishing the portfolio of ELIXIR Core Data Resources and ELIXIR Services is a key priority for ELIXIR and publicly marks the transition towards a cohesive infrastructure.

  17. Synthesis and reactivity of bis(tetramethylcyclopentadienyl) yttrium metallocenes including the reduction of Me(3)SiN(3) to [(Me(3)Si)(2)N](-) with [(C(5)Me(4)H)(2)Y(THF)](2)(mu-eta(2):eta(2)-N(2)).

    Science.gov (United States)

    Lorenz, Sara E; Schmiege, Benjamin M; Lee, David S; Ziller, Joseph W; Evans, William J

    2010-07-19

    The metallocene precursors needed to provide the tetramethylcyclopentadienyl yttrium complexes (C(5)Me(4)H)(3)Y, [(C(5)Me(4)H)(2)Y(THF)](2)(mu-eta(2):eta(2)-N(2)), and [(C(5)Me(4)H)(2)Y(mu-H)](2) for reactivity studies have been synthesized and fully characterized, and their reaction chemistry has led to an unexpected conversion of an azide to an amide. (C(5)Me(4)H)(2)Y(mu-Cl)(2)K(THF)(x), 1, synthesized from YCl(3) and KC(5)Me(4)H reacts with allylmagnesium chloride to make (C(5)Me(4)H)(2)Y(eta(3)-C(3)H(5)), 2, which is converted to [(C(5)Me(4)H)(2)Y][(mu-Ph)(2)BPh(2)], 3, with [Et(3)NH][BPh(4)]. Complex 3 reacts with KC(5)Me(4)H to form (C(5)Me(4)H)(3)Y, 4. The reduced dinitrogen complex, [(C(5)Me(4)H)(2)Y(THF)](2)(mu-eta(2):eta(2)-N(2)), 5, can be synthesized from either [(C(5)Me(4)H)(2)Y](2)[(mu-Ph)(2)BPh(2)], 3, or (C(5)Me(4)H)(3)Y, 4, with potassium graphite under a dinitrogen atmosphere. The (15)N labeled analogue, [(C(5)Me(4)H)(2)Y(THF)](2)(mu-eta(2):eta(2)-(15)N(2)), 5-(15)N, has also been prepared, and the (15)N NMR data have been compared to previously characterized reduced dinitrogen complexes. Complex 2 reacts with H(2) to form the corresponding hydride, [(C(5)Me(4)H)(2)Y(mu-H)](2), 6. Complex 5 displays similar reactivity to that of the analogous [(C(5)Me(4)H)(2)Ln(THF)](2)(mu-eta(2):eta(2)-N(2)) complexes (Ln = La, Lu), with substrates such as phenazine, anthracene, and CO(2). In addition, 5 reduces Me(3)SiN(3) to form (C(5)Me(4)H)(2)Y[N(SiMe(3))(2)], 7.

  18. Synthesis and characterisation of alkaline earth bis(diphenylphosphano)metallocene complexes and heterobimetallic alkaline earth metal/platinum(II) complexes [Ae(thf)(x)(η5-C5H4PPh2)2Pt(Me)2] (Ae = Ca, Sr, Ba).

    Science.gov (United States)

    Daniels, Daisy P; Deacon, Glen B; Harakat, Dominique; Jaroschik, Florian; Junk, Peter C

    2012-01-07

    A series of alkaline earth metallocene complexes carrying the diphenylphosphanocyclopentadienyl ligand, [Ae(L)(x)(η(5)-C(5)H(4)PPh(2))(2)] (Ae = Ca, L = thf, x = 1 (6a); Ae = Ca, L = dme, x = 1 (6b); Ae = Sr, L = thf, x = 1 (7); Ae = Ba, L = thf, x = 1 (8a); Ae = Ba, L = dme, x = 2 (8b)), were prepared by redox transmetallation/protolysis from the free metals, diphenylmercury and diphenylphosphanocyclopentadiene. These complexes were characterised using multinuclear NMR spectroscopy and two by single crystal X-ray diffraction. [Ca(dme)(η(5)-C(5)H(4)PPh(2))(2)] (6b) is a discrete neutral monomeric eight coordinate molecule in which the phosphorus atoms are not coordinated to the calcium ion and the larger barium analogue, ten-coordinate [Ba(dme)(2)(η(5)-C(5)H(4)PPh(2))(2)] (8b), has an extremely bent sandwich structure due to the two dme ligands attached to the metal. Bimetallic complexes, [Ae(thf)(x)(η(5)-C(5)H(4)PPh(2))(2)Pt(Me)(2)].(solv) (Ae = Ca, L = thf, x = 2, solv = 1.5thf (9); Ae = Sr, L = thf, x = 3, solv = 1.5thf (10); Ae = Ba, L = thf, x = 3, solv = thf (11)) were obtained by reaction of the homometallic complexes with [Pt(cod)(Me)(2)]. The crystal structures of [Ca(thf)(2)(η(5)-C(5)H(4)PPh(2))(2)Pt(Me)(2)].1.5thf (9), [Sr(thf)(3)(η(5)-C(5)H(4)PPh(2))(2)Pt(Me)(2)].1.5thf (10) and [Ba(thf)(3)(η(5)-C(5)H(4)PPh(2))(2)Pt(Me)(2)].thf (11) show the eight (calcium) and nine coordinate (strontium and barium) fragments acting as a chelating metalloligand attached to the square planar platinum through the phosphorus donor atoms. The solution chemistry of these bimetallic complexes has been investigated by NMR spectroscopy, electro-spray ionisation mass spectrometry and conductivity experiments which indicate that the bimetallic compounds persist in solution.

  19. Avaliação do desempenho de catalisadores híbridos Ziegler-Natta/metaloceno na homo- e copolimerização de etileno The performance evaluation of hybrid Ziegler-Natta/metallocene catalysts in homo- and copolymerization of ethylene

    Directory of Open Access Journals (Sweden)

    Fernanda O. V. Cunha

    2000-09-01

    Full Text Available Foram preparados catalisadores híbridos a partir de um catalisador do tipo Ziegler-Natta heterogêneo (MgCl2.TiCl4 e de um metalocênico (CpTiCl3, afim de se obter catalisadores com diferentes tipos de centros ativos. Foi proposta a formação de um novo centro ativo (CpTi(iBuCl2 na face 100 do suporte de MgCl2. Estes catalisadores foram avaliados na síntese de polietileno de alta densidade (PEAD e de polietileno linear de baixa densidade (PELBD, utilizando-se somente trietilalumínio (TEA como cocatalisador. Foi verificada a influência da razão molar Al/Ti, temperatura e tempo de polimerização na produtividade dos catalisadores e nas propriedades dos polímeros obtidos. Os catalisadores mistos apresentaram atividade catalítica da ordem de 5,0 kgPol/g cat.h na polimerização de etileno e da ordem de 7,0 kgPol/g cat.h na copolimerização etileno-1-buteno.Hybrid catalysts formed by a heterogeneous Ziegler-Natta catalyst (MgCl2.TiCl4 and a metallocene (CpTiCl3 were prepared in this work. The formation of a new catalytic species CpTi(iBuCl2 on the (100 MgCl2 face has been proposed. These catalyst systems were applied to synthesize high density polyethylene (HDPE and linear low density polyethylene (LLDPE, using only triethyl aluminium (TEA as a cocatalyst. The influence of Al/Ti molar ratio, temperature and time of polymerization on the catalyst activity and on the polymer properties were evaluated. The catalyst activities were about 5.0 kgPol/g cat.h for ethylene polymerization and 7.0 kgPol/g cat.h for ethylene-1-butene coplymerization.

  20. Synthesis of new dimeric carvacrol compounds

    Directory of Open Access Journals (Sweden)

    Uttam B. More

    2008-12-01

    Full Text Available The polymer supported carvacrol anion was reacted with 1,2-dibromoethane, 1,4-dibromoethane, oxalyl dichloride, malonyl dichloride, succinyl dichloride, glutaroyl dichloride, and adipoyl dichloride to afford the corresponding dimeric carvacryl ethers or esters

  1. Psychosocial counselling of identifiable sperm donors

    NARCIS (Netherlands)

    Visser, M.; Mochtar, M.H.; de Melker, A.A.; van der Veen, F.; Repping, S.; Gerrits, T.

    2016-01-01

    STUDY QUESTION: What do identifiable sperm donors feel about psychosocial counselling? SUMMARY ANSWER: Identifiable sperm donors found it important that psychosocial counselling focused on emotional consequences and on rules and regulations and they expected to have access to psychosocial

  2. Psychosocial counselling of identifiable sperm donors

    NARCIS (Netherlands)

    Visser, M. [=Marja; Mochtar, M. H.; de Melker, A. A.; van der Veen, F.; Repping, S.; Gerrits, T.

    2016-01-01

    What do identifiable sperm donors feel about psychosocial counselling? Identifiable sperm donors found it important that psychosocial counselling focused on emotional consequences and on rules and regulations and they expected to have access to psychosocial counselling at the time that

  3. Method of identifying plant pathogen tolerance

    Science.gov (United States)

    Ecker, J.R.; Staskawicz, B.J.; Bent, A.F.; Innes, R.W.

    1997-10-07

    A process for identifying a plant having disease tolerance comprising administering to a plant an inhibitory amount of ethylene and screening for ethylene insensitivity, thereby identifying a disease tolerant plant, is described. Plants identified by the foregoing process are also described. 7 figs.

  4. A probabilistic perspective on re-identifiability

    NARCIS (Netherlands)

    Koot, M.; Mandjes, M.; van 't Noordende, G.; de Laat, C.

    2013-01-01

    A quasi-identifier is a set of attributes that can be used to re-identify entries in anonymized data sets. A group of individuals is considered about whom quasi-identifying numerical information is disclosed such as date of birth, age, weight, and height. The fraction of individuals is determined

  5. Ability of Slovakian Pupils to Identify Birds

    Science.gov (United States)

    Prokop, Pavol; Rodak, Rastislav

    2009-01-01

    A pupil's ability to identify common organisms is necessary for acquiring further knowledge of biology. We investigated how pupils were able to identify 25 bird species following their song, growth habits, or both features presented simultaneously. Just about 19% of birds were successfully identified by song, about 39% by growth habit, and 45% of…

  6. 29 CFR 4010.7 - Identifying information.

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 9 2010-07-01 2010-07-01 false Identifying information. 4010.7 Section 4010.7 Labor Regulations Relating to Labor (Continued) PENSION BENEFIT GUARANTY CORPORATION CERTAIN REPORTING AND DISCLOSURE REQUIREMENTS ANNUAL FINANCIAL AND ACTUARIAL INFORMATION REPORTING § 4010.7 Identifying information...

  7. Water resources management in Tanzania: identifying research ...

    African Journals Online (AJOL)

    This paper aims at identifying research gaps and needs and recommendations for a research agenda on water resources management in Tanzania. We reviewed published literature on water resources management in Tanzania in order to highlight what is currently known, and to identify knowledge gaps, and suggest ...

  8. Identifying Needs and Opportunities for Local Government ...

    African Journals Online (AJOL)

    4carolinebell@gmail.com

    required for better environmental management and the establishment of education and training processes for .... The Education and Training Practices Project (NTB, 1998) identified important links between Applied ... to learn directly from departmental staff what education and training needs they identified with regard to ...

  9. Moving Beyond Weak Identifiers for Proxemic Interaction

    DEFF Research Database (Denmark)

    Sørensen, Henrik; Kjeldskov, Jesper

    2013-01-01

    is significantly closer than what is actually the case. This makes the smartphone a weak identifier for applications that need to track persons. With a focus on feasible interaction design, we present a concept and prototype of a platform, which seek to support proxemic interaction beyond weak identifiers...

  10. Learning environments matter: Identifying influences on the ...

    African Journals Online (AJOL)

    Hennie

    The students completed the Student Motivation for Science Learning questionnaire. Significant differences were identified between different groups and school types. The study is important for identifying the key role of achievement goals, science learning values and science self-efficacies. The main finding emphasises the.

  11. IDENTIFIABILITY VERSUS HETEROGENEITY IN GROUNDWATER MODELING SYSTEMS

    Directory of Open Access Journals (Sweden)

    A M BENALI

    2003-06-01

    Full Text Available Review of history matching of reservoirs parameters in groundwater flow raises the problem of identifiability of aquifer systems. Lack of identifiability means that there exists parameters to which the heads are insensitive. From the guidelines of the study of the homogeneous case, we inspect the identifiability of the distributed transmissivity field of heterogeneous groundwater aquifers. These are derived from multiple realizations of a random function Y = log T  whose probability distribution function is normal. We follow the identifiability of the autocorrelated block transmissivities through the measure of the sensitivity of the local derivatives DTh = (∂hi  ∕ ∂Tj computed for each sample of a population N (0; σY, αY. Results obtained from an analysis of Monte Carlo type suggest that the more a system is heterogeneous, the less it is identifiable.

  12. EZID: Long term identifiers made easy (Invited)

    Science.gov (United States)

    Starr, J.

    2013-12-01

    Scholarly research is producing ever increasing amounts of digital research data, and this data should be managed throughout the research life cycle both as part of good scientific practice, but also to comply with funder mandates, such as the 2013 OSTP Public Access Memo (http://www.whitehouse.gov/sites/default/files/microsites/ostp/ostp_public_access_memo_2013.pdf). By assigning unique and persistent identifiers to data objects, data managers can gain control and flexibility over what can be a daunting task. This is due to the fact that the objects can be moved to new locations without disruption to links, as long as the identifier target is maintained. EZID is a tool that makes assigning and maintaining unique, persistent identifiers easy. It was designed and built by California Digital Library (CDL) and has both a user interface and a RESTful API. EZID currently offers services for two globally unique, persistent identifier schemes: Digital Object Identifiers (DOIs) and Archival Resource Keys (ARKs). DOIs are identifiers originating from the publishing world and are in widespread use for journal articles. CDL is able to offer DOIs because of being a founding member of DataCite (http://www.datacite.org/), an international consortium established to provide easier access to scientific research data on the Internet. ARKs are identifiers originating from the library, archive and museum community. Like DOIs, they become persistent when the objects and identifier forwarding information is maintained. DOIs and ARKs have a key role in data management and, therefore, in data management plans. DOIs are the recommended identifier for use in data citation, and ARKs provide the maximum flexibility needed for data documentation and management throughout the early phases of a project. The two identifier schemes are able to be used together, and EZID is made to work with both. EZID clients, coming from education, research, government, and the private sector, are utilizing the

  13. Communicating identifiability risks to biobank donors

    DEFF Research Database (Denmark)

    Kasperbauer, T. J.; Gjerris, Mickey; Waldemar, Gunhild

    2018-01-01

    can track individuals across multiple databases. This article focuses on the communication of identifiability risks in the process of obtaining consent for donation and research. Most ethical discussions of identifiability risks have focused on the severity of the risk and how it might be mitigated......, and what precisely is at stake in pervasive data sharing. However, there has been little discussion of whether and how to communicate the risk to potential donors. We review the ethical arguments behind favoring different types of risk communication in the consent process, and outline how identifiability...... concerns can be incorporated into either a detailed or a simplified method of communicating risks during the consent process....

  14. Identifying Codes on Directed De Bruijn Graphs

    Science.gov (United States)

    2015-08-27

    JOURNAL ARTICLE (POST PRINT) 3. DATES COVERED (From - To) JUN 2013 – AUG 2015 4. TITLE AND SUBTITLE IDENTIFYING CODES ON DIRECTED DE BRUIJN GRAPHS 5a...owner. 14. ABSTRACT For a directed graph G, a t-identifying code is a subset S ⊆ V (G) with the property that for each vertex v ∈ V (G) the set of...vertices of S reachable from v by a directed path of length at most t is both non-empty and unique. A graph is called t- identifiable if there exists a

  15. Helping You Identify Quality Laboratory Services

    Science.gov (United States)

    Helping You Identify Quality Laboratory Services Selecting quality health care services for yourself, a relative or friend requires special thought and attention. The Joint Commission has prepared this information ...

  16. Identifiable Data Files - Health Outcomes Survey (HOS)

    Data.gov (United States)

    U.S. Department of Health & Human Services — The Medicare Health Outcomes Survey (HOS) identifiable data files are comprised of the entire national sample for a given 2-year cohort (including both respondents...

  17. Identifying significant environmental features using feature recognition.

    Science.gov (United States)

    2015-10-01

    The Department of Environmental Analysis at the Kentucky Transportation Cabinet has expressed an interest in feature-recognition capability because it may help analysts identify environmentally sensitive features in the landscape, : including those r...

  18. NIH Researchers Identify OCD Risk Gene

    Science.gov (United States)

    ... Issues Research News From NIH NIH Researchers Identify OCD Risk Gene Past Issues / Summer 2006 Table of ... gene variant that doubles an individual's risk for obsessive-compulsive disorder (OCD). The new functional variant, or allele, is ...

  19. ORCID Author Identifiers: A Primer for Librarians.

    Science.gov (United States)

    Akers, Katherine G; Sarkozy, Alexandra; Wu, Wendy; Slyman, Alison

    2016-01-01

    The ORCID (Open Researcher and Contributor ID) registry helps disambiguate authors and streamline research workflows by assigning unique 16-digit author identifiers that enable automatic linkages between researchers and their scholarly activities. This article describes how ORCID works, the benefits of using ORCID, and how librarians can promote ORCID at their institutions by raising awareness of ORCID, helping researchers create and populate ORCID profiles, and integrating ORCID identifiers into institutional repositories and other university research information systems.

  20. OCRWM baseline management procedure for document identifiers

    International Nuclear Information System (INIS)

    1993-03-01

    This procedure establishes a uniform numbering system (document identifier) for all Program and project technical, cost, and schedule baselines, and selected management and procurement documents developed for and controlled by the Office of Civilian Radioactive Waste Management (OCRWM) for the Civilian Radioactive Waste Management System (CRWMS). The document identifier defined in this procedure is structured to ensure that the relational integrity between configuration items (CIs) and their associated documentation and software is maintained, traceable, categorical, and retrievable for the life of the program

  1. Exploiting intrinsic fluctuations to identify model parameters.

    Science.gov (United States)

    Zimmer, Christoph; Sahle, Sven; Pahle, Jürgen

    2015-04-01

    Parameterisation of kinetic models plays a central role in computational systems biology. Besides the lack of experimental data of high enough quality, some of the biggest challenges here are identification issues. Model parameters can be structurally non-identifiable because of functional relationships. Noise in measured data is usually considered to be a nuisance for parameter estimation. However, it turns out that intrinsic fluctuations in particle numbers can make parameters identifiable that were previously non-identifiable. The authors present a method to identify model parameters that are structurally non-identifiable in a deterministic framework. The method takes time course recordings of biochemical systems in steady state or transient state as input. Often a functional relationship between parameters presents itself by a one-dimensional manifold in parameter space containing parameter sets of optimal goodness. Although the system's behaviour cannot be distinguished on this manifold in a deterministic framework it might be distinguishable in a stochastic modelling framework. Their method exploits this by using an objective function that includes a measure for fluctuations in particle numbers. They show on three example models, immigration-death, gene expression and Epo-EpoReceptor interaction, that this resolves the non-identifiability even in the case of measurement noise with known amplitude. The method is applied to partially observed recordings of biochemical systems with measurement noise. It is simple to implement and it is usually very fast to compute. This optimisation can be realised in a classical or Bayesian fashion.

  2. IDENTIFYING COLLISIONAL FAMILIES IN THE KUIPER BELT

    International Nuclear Information System (INIS)

    Marcus, Robert A.; Ragozzine, Darin; Murray-Clay, Ruth A.; Holman, Matthew J.

    2011-01-01

    The identification and characterization of numerous collisional families-clusters of bodies with a common collisional origin-in the asteroid belt has added greatly to the understanding of asteroid belt formation and evolution. More recent study has also led to an appreciation of physical processes that had previously been neglected (e.g., the Yarkovsky effect). Collisions have certainly played an important role in the evolution of the Kuiper Belt as well, though only one collisional family has been identified in that region to date, around the dwarf planet Haumea. In this paper, we combine insights into collisional families from numerical simulations with the current observational constraints on the dynamical structure of the Kuiper Belt to investigate the ideal sizes and locations for identifying collisional families. We find that larger progenitors (r ∼ 500 km) result in more easily identifiable families, given the difficulty in identifying fragments of smaller progenitors in magnitude-limited surveys, despite their larger spread and less frequent occurrence. However, even these families do not stand out well from the background. Identifying families as statistical overdensities is much easier than characterizing families by distinguishing individual members from interlopers. Such identification seems promising, provided the background population is well known. In either case, families will also be much easier to study where the background population is small, i.e., at high inclinations. Overall, our results indicate that entirely different techniques for identifying families will be needed for the Kuiper Belt, and we provide some suggestions.

  3. Distributed design approach in persistent identifiers systems

    Science.gov (United States)

    Golodoniuc, Pavel; Car, Nicholas; Klump, Jens

    2017-04-01

    The need to identify both digital and physical objects is ubiquitous in our society. Past and present persistent identifier (PID) systems, of which there is a great variety in terms of technical and social implementations, have evolved with the advent of the Internet, which has allowed for globally unique and globally resolvable identifiers. PID systems have catered for identifier uniqueness, integrity, persistence, and trustworthiness, regardless of the identifier's application domain, the scope of which has expanded significantly in the past two decades. Since many PID systems have been largely conceived and developed by small communities, or even a single organisation, they have faced challenges in gaining widespread adoption and, most importantly, the ability to survive change of technology. This has left a legacy of identifiers that still exist and are being used but which have lost their resolution service. We believe that one of the causes of once successful PID systems fading is their reliance on a centralised technical infrastructure or a governing authority. Golodoniuc et al. (2016) proposed an approach to the development of PID systems that combines the use of (a) the Handle system, as a distributed system for the registration and first-degree resolution of persistent identifiers, and (b) the PID Service (Golodoniuc et al., 2015), to enable fine-grained resolution to different information object representations. The proposed approach solved the problem of guaranteed first-degree resolution of identifiers, but left fine-grained resolution and information delivery under the control of a single authoritative source, posing risk to the long-term availability of information resources. Herein, we develop these approaches further and explore the potential of large-scale decentralisation at all levels: (i) persistent identifiers and information resources registration; (ii) identifier resolution; and (iii) data delivery. To achieve large-scale decentralisation

  4. Scalable persistent identifier systems for dynamic datasets

    Science.gov (United States)

    Golodoniuc, P.; Cox, S. J. D.; Klump, J. F.

    2016-12-01

    Reliable and persistent identification of objects, whether tangible or not, is essential in information management. Many Internet-based systems have been developed to identify digital data objects, e.g., PURL, LSID, Handle, ARK. These were largely designed for identification of static digital objects. The amount of data made available online has grown exponentially over the last two decades and fine-grained identification of dynamically generated data objects within large datasets using conventional systems (e.g., PURL) has become impractical. We have compared capabilities of various technological solutions to enable resolvability of data objects in dynamic datasets, and developed a dataset-centric approach to resolution of identifiers. This is particularly important in Semantic Linked Data environments where dynamic frequently changing data is delivered live via web services, so registration of individual data objects to obtain identifiers is impractical. We use identifier patterns and pattern hierarchies for identification of data objects, which allows relationships between identifiers to be expressed, and also provides means for resolving a single identifier into multiple forms (i.e. views or representations of an object). The latter can be implemented through (a) HTTP content negotiation, or (b) use of URI querystring parameters. The pattern and hierarchy approach has been implemented in the Linked Data API supporting the United Nations Spatial Data Infrastructure (UNSDI) initiative and later in the implementation of geoscientific data delivery for the Capricorn Distal Footprints project using International Geo Sample Numbers (IGSN). This enables flexible resolution of multi-view persistent identifiers and provides a scalable solution for large heterogeneous datasets.

  5. Identifying homelessness using health information exchange data.

    Science.gov (United States)

    Zech, John; Husk, Gregg; Moore, Thomas; Kuperman, Gilad J; Shapiro, Jason S

    2015-05-01

    Homeless patients experience poor health outcomes and consume a disproportionate amount of health care resources compared with domiciled patients. There is increasing interest in the federal government in providing care coordination for homeless patients, which will require a systematic way of identifying these individuals. We analyzed address data from Healthix, a New York City-based health information exchange, to identify patterns that could indicate homelessness. Patients were categorized as likely to be homeless if they registered with the address of a hospital, homeless shelter, place of worship, or an address containing a keyword synonymous with "homelessness." We identified 78,460 out of 7,854,927 Healthix patients (1%) as likely to have been homeless over the study period of September 30, 2008 to July 19, 2013. We found that registration practices for these patients varied widely across sites. The use of health information exchange data enabled us to identify a large number of patients likely to be homeless and to observe the wide variation in registration practices for homeless patients within and across sites. Consideration of these results may suggest a way to improve the quality of record matching for homeless patients. Validation of these results is necessary to confirm the homeless status of identified individuals. Ultimately, creating a standardized and structured field to record a patient's housing status may be a preferable approach. © The Author 2015. Published by Oxford University Press on behalf of the American Medical Informatics Association. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  6. Identifying glass compositions in fly ash

    Directory of Open Access Journals (Sweden)

    Katherine eAughenbaugh

    2016-01-01

    Full Text Available In this study, four Class F fly ashes were studied with a scanning electron microscope; the glassy phases were identified and their compositions quantified using point compositional analysis with k-means clustering and multispectral image analysis. The results showed that while the bulk oxide contents of the fly ashes were different, the four fly ashes had somewhat similar glassy phase compositions. Aluminosilicate glasses (AS, calcium aluminosilicate glasses (CAS, a mixed glass, and, in one case, a high iron glass were identified in the fly ashes. Quartz and iron crystalline phases were identified in each fly ash as well. The compositions of the three main glasses identified, AS, CAS, and mixed glass, were relatively similar in each ash. The amounts of each glass were varied by fly ash, with the highest calcium fly ash containing the most of calcium-containing glass. Some of the glasses were identified as intermixed in individual particles, particularly the calcium-containing glasses. Finally, the smallest particles in the fly ashes, with the most surface area available to react in alkaline solution, such as when mixed with portland cement or in alkali-activated fly ash, were not different in composition than the large particles, with each of the glasses represented. The method used in the study may be applied to a fly ash of interest for use as a cementing material in order to understand its potential for reactivity.

  7. The structure of fullerene films and their metallocene doping

    Energy Technology Data Exchange (ETDEWEB)

    Domrachev, G.A.; Kaverin, B.S.; Domracheva, E.G. [Institute of Organometallic Chemistry, Nizhnii Novgorod (Russian Federation)] [and others

    1995-02-01

    Hexagonal close-packed (HCP) C{sub 60} and C{sub 70} films have been prepared by the Langmuir method and examined by electron microscopy and electron-diffraction analysis. It has been shown that the vacuum deposition of a C{sub 60} + C{sub 70} mixture results in the formation of a film with small sized grains and a distorted C{sub 60}-HCP structure. The simultaneous deposition of C{sub 60} and ferrocene results in the formation of a film with a changed morphology and an electron-diffraction pattern that contains a variable amount of ferrocene depending on the experimental conditions. The electron-diffraction pattern corresponds to the presence of the known molecular complex C{sub 60}[(C{sub 5}H{sub 5}){sub 2}Fe]{sub 2}. The analogous simultaneous deposition of fullerene C{sub 60} and cobaltocene results in the formation of a C{sub 60} film stable in air and water, which contains carbon and cobalt (from the data of X-ray fluorescence, electron microscopy and microdiffraction). It has a different morphology and different diffraction patterns than pure C{sub 60} films and, depending on the cobaltocene content (relative to that of fullerene), appears to be a fullerite film doped with various amounts of cobaltocenium fulleride, which is an ionic compound.

  8. Surface coordination polymerization of ethylene by hydrozirconation-immobilized metallocene.

    Science.gov (United States)

    Zheng, Jun; Wang, Yanhui; Ye, Lin; Lin, Yichao; Tang, Tao; Zhang, Jidong

    2014-07-01

    Hydrozirconation on vinyl-terminated substrates (silicon wafer and nanosilica sphere) is employed as an efficient way for immobilization of zirconocene catalyst through Zr-C bonds, which is applied in surface coordination ethylene polymerization producing surface-tethered polyethylene (PE). The formation of Zr-C σ bond induced by hydrozirconation provides an initiator precursor for growing a layer of PE covalently linked onto substrates. The results from SEM, AFM, and TEM show that the surface polymerization is controlled by hydrozirconation. Surface pattern or core-shell structure with crystalline PE coating can be formed, when silicon wafer is selectively functionalized with vinyl-groups or vinyl-modified nanosilica is applied. It is believed that hydrozirconation for the synthesis of zirconocene initiator can be a versatile route to prepare polyolefin hybrid materials. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Analysis of superexchange coupling in metallocene-metallocenium redox pairs

    Energy Technology Data Exchange (ETDEWEB)

    Newton, M.D.; Ohta, K.; Zhong, E. (Brookhaven National Lab., Upton, NY (United States))

    1991-03-21

    Using a corresponding orbital approach implemented computational with the INDO method of Zerner et al, the authors have evaluated and analyzed the electron-transfer matrix elements (H{sub if}) for the ferrocene/ferrocenium and cobaltocene/cobaltocenium (Cp{sub 2}M/(Cp{sub 2}M){sup +}) electron exchange processes. Taking due account of the relative energies of different orientations of the reactants, they obtain good agreement with estimates of H{sub if} inferred from experimental kinetic data, as well as a detailed interpretation of the coupling based on a fully specified effective one-electron model. This model reveals distinct electronic mechanisms for the M = Fe and M = Co cases, corresponding, respectively, to superexchange of the 'electron' and 'hole' type. Variationally defined effective donor and acceptor orbitals are shown to be essentially equivalent to appropriately selected canonical molecular orbitals of the Cp{sub 2}M/(Cp{sub 2}M){sup +} transition-state complex. Departures from a simple one-electron model affect the calculated H{sub if} values by less than 10% (i.e., the many-electron core overlap integral is {approx gt} 0.9) even though the wave functions properly reflect the appreciable degree of electronic relaxation which is known to accompany the oxidation of the Cp{sub 2}M molecules. {sigma} as well as {pi}-type orbitals of the Cp rings are shown to play a significant role in facilitating the electronic coupling between reactants.

  10. Optimization of metallocene substrates for. beta. -cyclodextrin reactions

    Energy Technology Data Exchange (ETDEWEB)

    Breslow, R.; Trainor, G.; Ueno, A.

    1983-05-04

    The p-nitrophenyl ester of (E)-ruthenoceneacrylic acid reacts in a complex to acylate ..beta..-cyclodextrin, but with a poorer binding and rate constant than for the corresponding ferrocene derivative. The p-nitrophenyl ester of (E)-3-(carboxymethylene(-1,2-ferrocenocyclopentene is a mixture of two enantiomers. One enantiomer acylates ..beta..-cyclodextrin 5 900 000 times as fast in aqueous Me/sub 2/SO as it hydrolyzes under the same conditions (1.5 X 10/sup 8/ times as fast as hydrolysis in pure water at the same pH); the other enantiomer is 62-fold slower. These are the largest accelerations and enantiomeric selectives known for such reactions. Ferrocen-1,3-diacrylate esters react with ..beta..-cyclodextrin in processes in which the first and second acylation reveal important geometric effects. ..beta..-Cyclodextrin 6-tosylate is used to block unproductive binding and clarify the structural effects.

  11. Controlled spin switching in a metallocene molecular junction.

    Science.gov (United States)

    Ormaza, M; Abufager, P; Verlhac, B; Bachellier, N; Bocquet, M-L; Lorente, N; Limot, L

    2017-12-07

    The active control of a molecular spin represents one of the main challenges in molecular spintronics. Up to now spin manipulation has been achieved through the modification of the molecular structure either by chemical doping or by external stimuli. However, the spin of a molecule adsorbed on a surface depends primarily on the interaction between its localized orbitals and the electronic states of the substrate. Here we change the effective spin of a single molecule by modifying the molecule/metal interface in a controlled way using a low-temperature scanning tunneling microscope. A nickelocene molecule reversibly switches from a spin 1 to 1/2 when varying the electrode-electrode distance from tunnel to contact regime. This switching is experimentally evidenced by inelastic and elastic spin-flip mechanisms observed in reproducible conductance measurements and understood using first principle calculations. Our work demonstrates the active control over the spin state of single molecule devices through interface manipulation.

  12. Identifying Adverse Drug Events by Relational Learning.

    Science.gov (United States)

    Page, David; Costa, Vítor Santos; Natarajan, Sriraam; Barnard, Aubrey; Peissig, Peggy; Caldwell, Michael

    2012-07-01

    The pharmaceutical industry, consumer protection groups, users of medications and government oversight agencies are all strongly interested in identifying adverse reactions to drugs. While a clinical trial of a drug may use only a thousand patients, once a drug is released on the market it may be taken by millions of patients. As a result, in many cases adverse drug events (ADEs) are observed in the broader population that were not identified during clinical trials. Therefore, there is a need for continued, post-marketing surveillance of drugs to identify previously-unanticipated ADEs. This paper casts this problem as a reverse machine learning task , related to relational subgroup discovery and provides an initial evaluation of this approach based on experiments with an actual EMR/EHR and known adverse drug events.

  13. Photoacoustic tomography to identify inflammatory arthritis

    Science.gov (United States)

    Rajian, Justin Rajesh; Girish, Gandikota; Wang, Xueding

    2012-09-01

    Identifying neovascularity (angiogenesis) as an early feature of inflammatory arthritis can help in early accurate diagnosis and treatment monitoring of this disease. Photoacoustic tomography (PAT) is a hybrid imaging modality which relies on intrinsic differences in the optical absorption among the tissues being imaged. Since blood has highly absorbing chromophores including both oxygenated and deoxygenated hemoglobin, PAT holds potential in identifying early angiogenesis associated with inflammatory joint diseases. PAT is used to identify changes in the development of inflammatory arthritis in a rat model. Imaging at two different wavelengths, 1064 nm and 532 nm, on rats revealed that there is a significant signal enhancement in the ankle joints of the arthritis affected rats when compared to the normal control group. Histology images obtained from both the normal and the arthritis affected rats correlated well with the PAT findings. Results support the fact that the emerging PAT could become a new tool for clinical management of inflammatory arthritis.

  14. Identifying motivational factors within a multinational company

    Directory of Open Access Journals (Sweden)

    Daniela Bradutanu

    2011-08-01

    Full Text Available The aim of the study is to identify the main motivational factors within a multinational company. The first objective is to identify work functions, formulated on Abraham Maslow’s pyramid, following the identification of the key characteristics that motivate an employee at the work place and last, but not least, the type of motivation that employees focus, intrinsic or extrinsic. The research method targeted a questionnaire based survey, including various company employees and an interview with the manager. The results confirmed that in Romania, employees put great emphasis on extrinsic motivation, a certain income and job security being primary. These results have implications for managers that in order to effectively motivate staff, first, must know their needs and expectations. To identify the main needs and motivational factors we had as a starting point Maslow's pyramid.

  15. Identifying Walking Trips Using GPS Data.

    Science.gov (United States)

    Cho, Gi-Hyoug; Rodríguez, Daniel A; Evenson, Kelly R

    2011-02-01

    this study developed and tested algorithms to identify outdoor walking trips from portable global positioning system (GPS) units in free-living conditions. the study included a calibration and a validation phase. For the calibration phase, we determined the best algorithm from 35 person-days of data. Measures of agreement regarding the daily number and duration of diary-reported and GPS-identified trips were used. In the validation phase, the best algorithm was applied to an additional and separate 136 person-days of diary and GPS data. the preferred algorithm in the calibration phase resulted in 90% of trips identified from the GPS data being found in the diary, whereas 81% of trips reported in the diary being found in the GPS data. The preferred algorithm used 1) a maximum 3-min gap between points to define a trip, 2) at least 5 min or more of continuous GPS points, 3) a speed range between 2 and 8.0 km·h, 4) at least 30 m of displacement between the start and end points of a trip, and 5) merged walking trips when the time gap between trips was less than 3 min. With the validation data, substantial agreement between the GPS and the diary was achieved, with 86% of trips identified from the GPS data found in the diary and 77% of trips reported in the diary found in the GPS data. the algorithm identified free-living walking trips of more than 5 min in duration. The ability to identify outdoor walking trips from GPS data can be improved by reducing recording intervals used in the GPS units and monitoring participant compliance. Further research is desirable to determine whether concurrent wearing of an accelerometer may improve the ability to detect walking more accurately.

  16. Psychosocial counselling of identifiable sperm donors.

    Science.gov (United States)

    Visser, M; Mochtar, M H; de Melker, A A; van der Veen, F; Repping, S; Gerrits, T

    2016-05-01

    What do identifiable sperm donors feel about psychosocial counselling? Identifiable sperm donors found it important that psychosocial counselling focused on emotional consequences and on rules and regulations and they expected to have access to psychosocial counselling at the time that donor-offspring actually sought contact. Most studies on sperm donors are on anonymous donors and focus on recruitment, financial compensation, anonymity and motivations. There is limited knowledge on the value that identifiable sperm donors place on psychosocial counselling and what their needs are in this respect. We performed a qualitative study from March until June 2014 with 25 identifiable sperm donors, who were or had been a donor at the Centre for Reproductive Medicine of the Academic Medical Centre in Amsterdam any time between 1989 and 2014. We held semi-structured in-depth interviews with identifiable sperm donors with an average age of 44 years. The interviews were fully transcribed and analysed using the constant comparative method of grounded theory. Twelve out of 15 donors (former donors ITALIC! n = 8, active donors ITALIC! n = 7) who had received a counselling session during their intake procedure found it important that they had been able to talk about issues such as the emotional consequences of donation, disclosure to their own children, family and friends, future contact with donor-offspring and rules and regulations. Of the 10 former donors who had received no counselling session, 8 had regretted the lack of intensive counselling. In the years following their donation, most donors simply wanted to know how many offspring had been born using their sperm and had no need for further counselling. Nevertheless, they frequently mentioned that they were concerned about the well-being of 'their' offspring. In addition, they would value the availability of psychosocial counselling in the event that donor-offspring actually sought contact. A limitation of our study is its

  17. Minimal covariant observables identifying all pure states

    Energy Technology Data Exchange (ETDEWEB)

    Carmeli, Claudio, E-mail: claudio.carmeli@gmail.com [D.I.M.E., Università di Genova, Via Cadorna 2, I-17100 Savona (Italy); I.N.F.N., Sezione di Genova, Via Dodecaneso 33, I-16146 Genova (Italy); Heinosaari, Teiko, E-mail: teiko.heinosaari@utu.fi [Turku Centre for Quantum Physics, Department of Physics and Astronomy, University of Turku (Finland); Toigo, Alessandro, E-mail: alessandro.toigo@polimi.it [Dipartimento di Matematica, Politecnico di Milano, Piazza Leonardo da Vinci 32, I-20133 Milano (Italy); I.N.F.N., Sezione di Milano, Via Celoria 16, I-20133 Milano (Italy)

    2013-09-02

    It has been recently shown by Heinosaari, Mazzarella and Wolf (2013) [1] that an observable that identifies all pure states of a d-dimensional quantum system has minimally 4d−4 outcomes or slightly less (the exact number depending on d). However, no simple construction of this type of minimal observable is known. We investigate covariant observables that identify all pure states and have minimal number of outcomes. It is shown that the existence of this kind of observables depends on the dimension of the Hilbert space.

  18. Molecular Fingerprints to Identify Candida Species

    Directory of Open Access Journals (Sweden)

    Claudia Spampinato

    2013-01-01

    Full Text Available A wide range of molecular techniques have been developed for genotyping Candida species. Among them, multilocus sequence typing (MLST and microsatellite length polymorphisms (MLP analysis have recently emerged. MLST relies on DNA sequences of internal regions of various independent housekeeping genes, while MLP identifies microsatellite instability. Both methods generate unambiguous and highly reproducible data. Here, we review the results achieved by using these two techniques and also provide a brief overview of a new method based on high-resolution DNA melting (HRM. This method identifies sequence differences by subtle deviations in sample melting profiles in the presence of saturating fluorescent DNA binding dyes.

  19. Identifying gaps in international food safety regulation.

    Science.gov (United States)

    McGrady, Benn; Ho, Christina S

    2011-01-01

    The rise in food importation in countries such as the United States, coupled with food safety incidents, has led to increased concern with the safety of imported food. This concern has prompted discussion of how international law and governance mechanisms might enhance food safety. This paper identifies the objectives underlying multilateral approaches to food safety such as raising food safety standards abroad, information sharing and ensuring market access. The paper then explores how these objectives are integrated into the international system and identifies how the current state of the law creates imbalances in the pursuit of these objectives.

  20. Identifying jet quantum numbers event by event

    International Nuclear Information System (INIS)

    Teper, M.J.

    1979-12-01

    A method is proposed to identify the parton that gives rise to any particular jet. The method improves with the number of particles in the jet, and should indicate which of the jets in a three jet event at PETRA is the gluon jet. (author)

  1. Structural identifiability of polynomial and rational systems

    NARCIS (Netherlands)

    J. Nemcová (Jana)

    2010-01-01

    htmlabstractSince analysis and simulation of biological phenomena require the availability of their fully specified models, one needs to be able to estimate unknown parameter values of the models. In this paper we deal with identifiability of parametrizations which is the property of one-to-one

  2. Identifying motifs in folktales using topic models

    NARCIS (Netherlands)

    Karsdorp, F.; Bosch, A.P.J. van den

    2013-01-01

    With the undertake of various folktale digitalization initiatives, the need for computational aids to explore these collections is increasing. In this paper we compare Labeled LDA (L-LDA) to a simple retrieval model on the task of identifying motifs in folktales. We show that both methods are well

  3. 10 Ways to Identify Hearing Loss

    Science.gov (United States)

    ... of this page please turn JavaScript on. Feature: Hearing Loss 10 Ways to Identify Hearing Loss Past Issues / Spring 2015 Table of Contents If ... gov Internet: www.nidcd.nih.gov Read More "Hearing Loss" Articles Managing Hearing Loss / Symptoms, Devices, Prevention & Research / ...

  4. Identifying Mixtures of Mixtures Using Bayesian Estimation

    Science.gov (United States)

    Malsiner-Walli, Gertraud; Frühwirth-Schnatter, Sylvia; Grün, Bettina

    2017-01-01

    ABSTRACT The use of a finite mixture of normal distributions in model-based clustering allows us to capture non-Gaussian data clusters. However, identifying the clusters from the normal components is challenging and in general either achieved by imposing constraints on the model or by using post-processing procedures. Within the Bayesian framework, we propose a different approach based on sparse finite mixtures to achieve identifiability. We specify a hierarchical prior, where the hyperparameters are carefully selected such that they are reflective of the cluster structure aimed at. In addition, this prior allows us to estimate the model using standard MCMC sampling methods. In combination with a post-processing approach which resolves the label switching issue and results in an identified model, our approach allows us to simultaneously (1) determine the number of clusters, (2) flexibly approximate the cluster distributions in a semiparametric way using finite mixtures of normals and (3) identify cluster-specific parameters and classify observations. The proposed approach is illustrated in two simulation studies and on benchmark datasets. Supplementary materials for this article are available online. PMID:28626349

  5. Congenital Heart Diseases associated with Identified Syndromes ...

    African Journals Online (AJOL)

    Recognised syndromes were seen in 69(68%) cases. Down syndrome with 54 children contributed 78.3% of those with known syndromes. Other identified syndromes and associations were Marfan's, Noonan's, Edwards, Prune Belly, Apert, Ellis-van creveld syndrome and congenital rubella syndrome. Congenital heart ...

  6. Transverse momentum distributions of identified particles produced ...

    Indian Academy of Sciences (India)

    We assume that the transverse momentum distributions of identified particles measured in final state are contributed by a few energy sources which can be regarded as partons or quarks in the interacting system. The particle is contributed by each source with gluons which have transverse momentum distributions in an ...

  7. Teaching science students to identify entrepreneurial opportunities

    NARCIS (Netherlands)

    Nab, J.|info:eu-repo/dai/nl/304827614

    2015-01-01

    This dissertation describes a research project on teaching science students to identify entrepreneurial opportunities, which is a core competence for entrepreneurs that should be emphasized in education. This research consists of four studies. The first case study aims at finding design strategies

  8. Identifying Protein-Calorie Malnutrition Workshop.

    Science.gov (United States)

    Walker, Susan S.; Barker, Ellen M.

    Instructional materials are provided for a workshop to enable participants to assist in identifying patients at risk with protein-calorie malnutrition and in corrrecting this nutritional deficiency. Representative topics are nutrients; protein, mineral, and vitamin sources, functions, and deficiency symptoms; malnutrition; nutritional deficiency…

  9. Identifying Ethical Hypernorms for Accounting Educators

    Science.gov (United States)

    Siegel, Philip H.; Mintz, Steven; Naser-Tavakolian, Mohsen; O'Shaughnessy, John

    2012-01-01

    Accounting educators have a unique role in academe because students learn about codes of ethics that will guide their actions as professionals. We identify hypernorms related to internal auditing educators that reflect unethical behaviors believed to be universally unacceptable by that community. We then compare the results to a prior survey of…

  10. Identifying Sexual Harassment: A Classroom Activity

    Science.gov (United States)

    Madson, Laura; Shoda, Jennifer

    2002-01-01

    We created a classroom activity to illustrate the complexity involved in identifying sexual harassment. In the activity, students decided whether 6 fictional scenarios constituted sexual harassment. The activity stimulates animated discussion, and evaluation data indicate that it received positive feedback from students and refined students'…

  11. Problems Identifying Independent and Dependent Variables

    Science.gov (United States)

    Leatham, Keith R.

    2012-01-01

    This paper discusses one step from the scientific method--that of identifying independent and dependent variables--from both scientific and mathematical perspectives. It begins by analyzing an episode from a middle school mathematics classroom that illustrates the need for students and teachers alike to develop a robust understanding of…

  12. Representing biodiversity: data and procedures for identifying ...

    Indian Academy of Sciences (India)

    Unknown

    alternative uses of biological resources, the methods for identifying priority areas have to ... conservation investment and make enlightened trade-offs. Negotiation can be ..... The energy and commitment of those involved in the Costa Rican. Figure 1. Three kinds of areas × features matrices showing (A) presence only data,.

  13. Identifying the Multiple Intelligences of Your Students

    Science.gov (United States)

    McClellan, Joyce A.; Conti, Gary J.

    2008-01-01

    One way of addressing individual differences among adult learners is to identify the Multiple Intelligences of the learner. Multiple Intelligences refers to the concept developed by Howard Gardner that challenges the traditional view of intelligence and explains the presence of nine different Multiple Intelligences. The purpose of this study was…

  14. Understanding intercellular communication in the brain: Identified ...

    Indian Academy of Sciences (India)

    Understanding intercellular communication in the brain: Identified neuromuscular synapses of the fruitfly. Drosophila serve as a model. The transmission of information between nerve cells in the brain takes place at specialized sites of contact, the synapses. Spatial interactions between synapses and temporal modulation of ...

  15. Klebsiella pneumoniae antibiotic resistance identified by atomic ...

    Indian Academy of Sciences (India)

    In particular, we studied Klebsiella pneumoniae bacteria provided by the Lavagna Hospital ASL4Liguria (Italy), where there are cases linked with antibiotics resistance of the Klebsiella pneumoniae. By comparing AFMimages of bacteria strains treated with different antibiotics is possible to identify unambiguously the ...

  16. Avoiding medication mixups. Identifiable imprint codes.

    Science.gov (United States)

    Vasudevan, P; Del Gianni, T; Robertson, W O

    1996-01-01

    This study was done to determine if current imprinting of solid medication forms permits health care professionals to identify the manufacturers involved so as to be able to activate the hierarchic identification system mandated by the Food and Drug Administration. We tested 15 representatives of 6 groups of health professionals for their ability to identify the manufacturer after having examined 30 solid-dosage forms drawn from a pseudo-random sample of stock hospital formulary products. The correct identification of the manufacturer was the sole criterion. Of the 2,700 opportunities, the manufacturer was able to be identified for only 43%. Nurses and medical students had a 35% success rate, pharmacists and poison center specialists a 55% success rate, and residents and attending physicians a 40% rate. None approached 95% accuracy. Currently employed imprints fail in their objective to permit health care professionals--or the general public--to rapidly identify prescription drugs. The manufacturers' logotypes need to be modified if this identification system is to be implemented. We propose a simple voluntary collaborative effort by the pharmaceutical industry to solve the problem. PMID:9000855

  17. Identifying Barriers to Study Abroad Program Participation

    Science.gov (United States)

    McKinley, Karen E.

    2014-01-01

    University administrators, industry professionals, and government leaders encourage college students to participate in study abroad programs. Despite an increase in the number of students going abroad, the percentage of students participating in global programs remain low. This study identified barriers to study abroad program participation at a…

  18. Identifying Teaching Methods that Engage Entrepreneurship Students

    Science.gov (United States)

    Balan, Peter; Metcalfe, Mike

    2012-01-01

    Purpose: Entrepreneurship education particularly requires student engagement because of the complexity of the entrepreneurship process. The purpose of this paper is to describe how an established measure of engagement can be used to identify relevant teaching methods that could be used to engage any group of entrepreneurship students.…

  19. Identifying systematic DFT errors in catalytic reactions

    DEFF Research Database (Denmark)

    Christensen, Rune; Hansen, Heine Anton; Vegge, Tejs

    2015-01-01

    Using CO2 reduction reactions as examples, we present a widely applicable method for identifying the main source of errors in density functional theory (DFT) calculations. The method has broad applications for error correction in DFT calculations in general, as it relies on the dependence...

  20. Identifying particular places through experimental walking

    Directory of Open Access Journals (Sweden)

    Henrik Schultz

    2016-11-01

    Full Text Available Experimental walking can be used to identify particular places, design strategies and spatial visions for urban landscapes. Walking designers can explore sites and, in particular, their temporal dynamics and atmospheric particularities – both essential elements in making particular places. This article illustrates the benefits of this method, using the changing German city of Freiburg as an example.

  1. Identifying Foods causing Allergies/ Intolerances among Diabetic ...

    African Journals Online (AJOL)

    Objective: This study was designed to identify the foods that caused allergies / intolerances and symptoms of reaction experienced by diabetic patients attending State Specialist Hospital, Akure. Materials and Methods: Ninety-eight diabetics aged 30-80 years (30 males and 68 females) were included in the study.

  2. Synthesis and reactions of ({eta}{sup 5}-C{sub 5}Me{sub 4}-2-C{sub 5}H{sub 4}N){sub 2}UCl{sub 2} and its derivatives, including the puzzling formation of the ansa-metallocene C{sub 2}H{sub 4}({eta}{sup 5}-C{sub 5}Me{sub 3}-2-C{sub 5}H{sub 4}N){sub 2}UCl{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Moisan, L.; Le Borgne, Th.; Villiers, C.; Thuery, P.; Ephritikhine, M. [CEA Saclay, Dept. de Recherche sur l' Etat Condense, les Atomes et les Molecules, Service de Chimie Moleculaire, Laboratoire Claude-Frejacques (CNRS URA 331), 91 - Gif sur Yvette (France)

    2007-10-15

    Reaction of UCl{sub 4} with Li(C{sub 5}Me{sub 4}-2-C{sub 5}H{sub 4}N) (LiCp{sup *}Py) gave (Cp{sup *}Py){sub 2}UCl{sub 2} (1), which was subsequently transformed into (Cp{sup *}Py){sub 2}UX{sub 2} [X = Me (2), BH{sub 4} (3)]. Treatment of 3 with HNEt{sub 3}BPh{sub 4} afforded the cationic derivative [(Cp{sup *}Py){sub 2}U(BH{sub 4})][BPh{sub 4}]. The ansa-metallocene C{sub 2}H{sub 4}({eta}{sup 5}-C{sub 5}Me{sub 3}-2-C{sub 5}H{sub 4}N){sub 2}UCl{sub 2} (5) was unexpectedly obtained in one reaction of 2 and CuCl{sub 2}. The crystal structures of 1 and 5 have been determined. (authors)

  3. Guidelines for identifying suspect/counterfeit material

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-09-01

    These guidelines are intended to assist users of products in identifying: substandard, misrepresented, or fraudulently marked items. The guidelines provide information about such topics as: precautions, inspection and testing, dispositioning identified items, installed inspection and reporting suspect/counterfeit materials. These guidelines apply to users who are developing procurement documents, product acceptance/verification methods, company procedures, work instructions, etc. The intent of these SM guidelines in relation to the Quality Assurance Program Description (QAPD) and implementing company Management Control Procedures is not to substitute or replace existing requirements, as defined in either the QAPD or company implementing instructions (Management Control Procedures). Instead, the guidelines are intended to provide a consolidated source of information addressing the issue of Suspect/Counterfeit materials. These guidelines provide an extensive suspect component listing and suspect indications listing. Users can quickly check their suspect items against the list of manufacturers products (i.e., type, LD. number, and nameplate information) by consulting either of these listings.

  4. Persistent Identifiers for Dutch cultural heritage institutions

    Science.gov (United States)

    Ras, Marcel; Kruithof, Gijsbert

    2016-04-01

    Over the past years, more and more collections belonging to archives, libraries, media, museums, and knowledge institutes are being digitised and made available online. These are exciting times for ALM institutions. They are realising that, in the information society, their collections are goldmines. Unfortunately most heritage institutions in the Netherlands do not yet meet the basic preconditions for long-term availability of their collections. The digital objects often have no long lasting fixed reference yet. URL's and web addresses change. Some digital objects that were referenced in Europeana and other portals can no longer be found. References in scientific articles have a very short life span, which is damaging for scholarly research. In 2015, the Dutch Digital Heritage Network (NDE) has started a two-year work program to co-ordinate existing initiatives in order to improve the (long-term) accessibility of the Dutch digital heritage for a wide range of users, anytime, anyplace. The Digital Heritage Network is a partnership established on the initiative of the Ministry of Education, Culture and Science. The members of the NDE are large, national institutions that strive to professionally preserve and manage digital data, e.g. the National Library, The Netherlands Institute for Sound and Vision, the Netherlands Cultural Heritage Agency, the Royal Netherlands Academy of Arts and Sciences, the National Archive of the Netherlands and the DEN Foundation, and a growing number of associations and individuals both within and outside the heritage sector. By means of three work programmes the goals of the Network should be accomplished and improve the visibility, the usability and the sustainability of digital heritage. Each programme contains of a set of projects. Within the sustainability program a project on creating a model for persistent identifiers is taking place. The main goals of the project are (1) raise awareness among cultural heritage institutions on the

  5. An Xpert screen to identify carbapenemases

    Directory of Open Access Journals (Sweden)

    Mubin Kazi

    2016-01-01

    Full Text Available To prevent the spread of carbapenemases-producing Enterobacteriaceae (CPE active surveillance, contact isolation and cohorting infected patients should be practiced. Rectal swabs for the Xpert MDRO-assay of 32 patients were included. 71.85% were positive for targets incorporated into the MDRO-assay; whereas 28% were phenotypically not CRE and Xpert negative (9.37% had different mechanism [bla OXA]. The assay identified 59.3%, 9.37% and 3.1% as bla NDM, bla NDM+VIM and bla VIM, respectively. The assay is a screening test that identifies CPE harbouring organism within an hour and can be installed at tertiary-care facilities to screen colonized patients.

  6. Identifying Critical States through the Relevance Index

    Directory of Open Access Journals (Sweden)

    Andrea Roli

    2017-02-01

    Full Text Available The identification of critical states is a major task in complex systems, and the availability of measures to detect such conditions is of utmost importance. In general, criticality refers to the existence of two qualitatively different behaviors that the same system can exhibit, depending on the values of some parameters. In this paper, we show that the relevance index may be effectively used to identify critical states in complex systems. The relevance index was originally developed to identify relevant sets of variables in dynamical systems, but in this paper, we show that it is also able to capture features of criticality. The index is applied to two prominent examples showing slightly different meanings of criticality, namely the Ising model and random Boolean networks. Results show that this index is maximized at critical states and is robust with respect to system size and sampling effort. It can therefore be used to detect criticality.

  7. Relationship between flanker identifiability and compatibility effect.

    Science.gov (United States)

    Schwarz, W; Mecklinger, A

    1995-10-01

    What is the relation between the identifiability of masked flankers and their ability to induce compatibility effects in a letter classification task? Using a within-subjects design (n = 8), we first determined identification performance for two flankers (H or N) around an irrelevant target letter as a function of the time (stimulus onset asynchrony, or SOA) after which the flankers were masked. In a second condition, subjects classified the central letter of the same stimulus patterns irrespectively of the identity of the flankers. The compatibility effects increased with increasing identification performance as a function of SOA, and we found a significant compatibility effect even at an SOA at which the identifiability of the flankers did not differ significantly from zero. We discuss the statistical power of our design and an interpretation of our results in terms of a dissociation between perceptual processes and processes directly activating the motor system (direct parameter specification; cf. Neumann, 1990).

  8. Trustworthy persistent identifier systems of the future

    Science.gov (United States)

    Golodoniuc, Pavel; Klump, Jens; Car, Nicholas

    2016-04-01

    Over the last two decades, persistent identifier (PID) systems have seen some significant changes in their governance policies, system capabilities, and technology. The development of most systems was driven by two main application areas, namely archives and libraries. Guidelines and criteria for trustworthy PID systems have been clearly devised (Bütikofer, 2009) and many PID system implementations for the identification of static digital objects have been built (e.g., PURL). However systems delivering persistent identifiers for dynamic datasets are not yet mature. There has been a rapid proliferation of different PID systems caused by the specific technical or organisational requirements of various communities that could not be met by existing systems such as DOI, ISBN, and EAN. Many of these different systems were limited by their inability to provide native means of persistent identifier resolution. This has prompted a decoupling of PID-associated data from the resolution service and this is where the Handle system has played a significant role. The Handle allowed to build a distributed system of independently managed resolver services. A trustworthy PID system must be designed to outlive the objects it provides persistent identifiers for, which may cease to exist or otherwise be deprecated, and the technology used to implement it, which will certainly need to change with time. We propose that such a system should rest on four pillars of agreements - (i) definitions, (ii) policies, (iii) services, and (iv) data services, to ensure longevity. While we believe all four pillars are equally important, we intentionally leave regulating aspects of issuing of identifiers and their registration out of the scope of this paper and focus on the agreements that have to be established between PID resolver services and the data sources indicated by the persistent identifiers. We propose an approach to development of PID systems that combines the use of (a) the Handle system

  9. Identifying mechanistic similarities in drug responses

    KAUST Repository

    Zhao, C.

    2012-05-15

    Motivation: In early drug development, it would be beneficial to be able to identify those dynamic patterns of gene response that indicate that drugs targeting a particular gene will be likely or not to elicit the desired response. One approach would be to quantitate the degree of similarity between the responses that cells show when exposed to drugs, so that consistencies in the regulation of cellular response processes that produce success or failure can be more readily identified.Results: We track drug response using fluorescent proteins as transcription activity reporters. Our basic assumption is that drugs inducing very similar alteration in transcriptional regulation will produce similar temporal trajectories on many of the reporter proteins and hence be identified as having similarities in their mechanisms of action (MOA). The main body of this work is devoted to characterizing similarity in temporal trajectories/signals. To do so, we must first identify the key points that determine mechanistic similarity between two drug responses. Directly comparing points on the two signals is unrealistic, as it cannot handle delays and speed variations on the time axis. Hence, to capture the similarities between reporter responses, we develop an alignment algorithm that is robust to noise, time delays and is able to find all the contiguous parts of signals centered about a core alignment (reflecting a core mechanism in drug response). Applying the proposed algorithm to a range of real drug experiments shows that the result agrees well with the prior drug MOA knowledge. © The Author 2012. Published by Oxford University Press. All rights reserved.

  10. Identifiability Scaling Laws in Bilinear Inverse Problems

    OpenAIRE

    Choudhary, Sunav; Mitra, Urbashi

    2014-01-01

    A number of ill-posed inverse problems in signal processing, like blind deconvolution, matrix factorization, dictionary learning and blind source separation share the common characteristic of being bilinear inverse problems (BIPs), i.e. the observation model is a function of two variables and conditioned on one variable being known, the observation is a linear function of the other variable. A key issue that arises for such inverse problems is that of identifiability, i.e. whether the observa...

  11. Discrimination of SM-Identified Individuals

    OpenAIRE

    Wright, Susan

    2006-01-01

    The misconception that sadomasochism (SM) is violence or abusive behavior has resulted in significant persecution against SM-identified individuals in the form of discrimination, harassment and physical attacks. Historically, women who practiced SM were targeted within the feminist movement due to official opposition against sadomasochistic practices led by the National Organization for Women (NOW). Current statistics of incidents of discrimination, harassment and physical attacks against SM-...

  12. Which functional unit to identify sustainable foods?

    Science.gov (United States)

    Masset, Gabriel; Vieux, Florent; Darmon, Nicole

    2015-09-01

    In life-cycle assessment, the functional unit defines the unit for calculation of environmental indicators. The objective of the present study was to assess the influence of two functional units, 100 g and 100 kcal (420 kJ), on the associations between three dimensions for identifying sustainable foods, namely environmental impact (via greenhouse gas emissions (GHGE)), nutritional quality (using two distinct nutrient profiling systems) and price. GHGE and price data were collected for individual foods, and were each expressed per 100 g and per 100 kcal. Two nutrient profiling models, SAIN,LIM and UK Ofcom, were used to assess foods' nutritional quality. Spearman correlations were used to assess associations between variables. Sustainable foods were identified as those having more favourable values for all three dimensions. The French Individual and National Dietary Survey (INCA2), 2006-2007. Three hundred and seventy-three foods highly consumed in INCA2, covering 65 % of total energy intake of adult participants. When GHGE and price were expressed per 100 g, low-GHGE foods had a lower price and higher SAIN,LIM and Ofcom scores (r=0·59, -0·34 and -0·43, respectively), suggesting a compatibility between the three dimensions; 101 and 100 sustainable foods were identified with SAIN,LIM and Ofcom, respectively. When GHGE and price were expressed per 100 kcal, low-GHGE foods had a lower price but also lower SAIN,LIM and Ofcom scores (r=0·67, 0·51 and 0·47, respectively), suggesting that more environment-friendly foods were less expensive but also less healthy; thirty-four sustainable foods were identified with both SAIN,LIM and Ofcom. The choice of functional unit strongly influenced the compatibility between the sustainability dimensions and the identification of sustainable foods.

  13. The Complexity of Identifying Large Equivalence Classes

    DEFF Research Database (Denmark)

    Skyum, Sven; Frandsen, Gudmund Skovbjerg; Miltersen, Peter Bro

    1999-01-01

    We prove that at least 3k−4/k(2k−3)(n/2) – O(k)equivalence tests and no more than 2/k (n/2) + O(n) equivalence tests are needed in the worst case to identify the equivalence classes with at least k members in set of n elements. The upper bound is an improvement by a factor 2 compared to known res...

  14. Transverse momentum distributions of identified particles produced ...

    Indian Academy of Sciences (India)

    Comparisons with experimental data. The pT spectra, in different presentation forms as used in [11,28–31], for identified parti- cles emitted in pp collisions at different centre-of-mass energies are shown in figures 1–4, where y, E, p, σ, and B denote the rapidity, energy, momentum, cross-section, and di- lepton branching ratio ...

  15. Identifying the Universal part of TMDs

    CERN Document Server

    Van der Veken, F.F.

    2016-01-01

    We attempt to identify a path layout in the definition of transverse-momentum-dependent T-odd parton distribution functions (TMD)s which combines features of both, initial- and final-state interactions, so that it remains universal despite the fact that the Wilson lines entering such TMDs change their orientation. The generic structure of the quark correlator for this path layout is calculated.

  16. Have No PHEAR: Networks Without Identifiers

    Science.gov (United States)

    2015-12-07

    Ethernet and TCP/IP were not designed to ensure the security and privacy of users. To protect users’ pri- vacy, anonymity networks such as Tor have been...protocols that power the Internet were not developed with the security and privacy of users in mind, there are many opportunities for on-path network...IEEE 802 network (such as Eth- ernet or Wireless Ethernet networks, for example). This address is a globally unique identifier for the device’s network

  17. Identifying Topics in Microblogs Using Wikipedia.

    Directory of Open Access Journals (Sweden)

    Ahmet Yıldırım

    Full Text Available Twitter is an extremely high volume platform for user generated contributions regarding any topic. The wealth of content created at real-time in massive quantities calls for automated approaches to identify the topics of the contributions. Such topics can be utilized in numerous ways, such as public opinion mining, marketing, entertainment, and disaster management. Towards this end, approaches to relate single or partial posts to knowledge base items have been proposed. However, in microblogging systems like Twitter, topics emerge from the culmination of a large number of contributions. Therefore, identifying topics based on collections of posts, where individual posts contribute to some aspect of the greater topic is necessary. Models, such as Latent Dirichlet Allocation (LDA, propose algorithms for relating collections of posts to sets of keywords that represent underlying topics. In these approaches, figuring out what the specific topic(s the keyword sets represent remains as a separate task. Another issue in topic detection is the scope, which is often limited to specific domain, such as health. This work proposes an approach for identifying domain-independent specific topics related to sets of posts. In this approach, individual posts are processed and then aggregated to identify key tokens, which are then mapped to specific topics. Wikipedia article titles are selected to represent topics, since they are up to date, user-generated, sophisticated articles that span topics of human interest. This paper describes the proposed approach, a prototype implementation, and a case study based on data gathered during the heavily contributed periods corresponding to the four US election debates in 2012. The manually evaluated results (0.96 precision and other observations from the study are discussed in detail.

  18. Identifying Topics in Microblogs Using Wikipedia.

    Science.gov (United States)

    Yıldırım, Ahmet; Üsküdarlı, Suzan; Özgür, Arzucan

    2016-01-01

    Twitter is an extremely high volume platform for user generated contributions regarding any topic. The wealth of content created at real-time in massive quantities calls for automated approaches to identify the topics of the contributions. Such topics can be utilized in numerous ways, such as public opinion mining, marketing, entertainment, and disaster management. Towards this end, approaches to relate single or partial posts to knowledge base items have been proposed. However, in microblogging systems like Twitter, topics emerge from the culmination of a large number of contributions. Therefore, identifying topics based on collections of posts, where individual posts contribute to some aspect of the greater topic is necessary. Models, such as Latent Dirichlet Allocation (LDA), propose algorithms for relating collections of posts to sets of keywords that represent underlying topics. In these approaches, figuring out what the specific topic(s) the keyword sets represent remains as a separate task. Another issue in topic detection is the scope, which is often limited to specific domain, such as health. This work proposes an approach for identifying domain-independent specific topics related to sets of posts. In this approach, individual posts are processed and then aggregated to identify key tokens, which are then mapped to specific topics. Wikipedia article titles are selected to represent topics, since they are up to date, user-generated, sophisticated articles that span topics of human interest. This paper describes the proposed approach, a prototype implementation, and a case study based on data gathered during the heavily contributed periods corresponding to the four US election debates in 2012. The manually evaluated results (0.96 precision) and other observations from the study are discussed in detail.

  19. Identified particles in quark and gluon jets

    CERN Document Server

    Abreu, P; Adye, T; Ajinenko, I; Alekseev, G D; Alemany, R; Allport, P P; Almehed, S; Amaldi, Ugo; Amato, S; Andreazza, A; Andrieux, M L; Antilogus, P; Apel, W D; Åsman, B; Augustin, J E; Augustinus, A; Baillon, Paul; Bambade, P; Barão, F; Barbi, M S; Barbiellini, Guido; Bardin, Dimitri Yuri; Barker, G; Baroncelli, A; Bärring, O; Barrio, J A; Bartl, Walter; Bates, M J; Battaglia, Marco; Baubillier, M; Baudot, J; Becks, K H; Begalli, M; Beillière, P; Belokopytov, Yu A; Benvenuti, Alberto C; Berggren, M; Bertini, D; Bertrand, D; Besançon, M; Bianchi, F; Bigi, M; Bilenky, S M; Billoir, P; Bizouard, M A; Bloch, D; Blume, M; Bolognese, T; Bonesini, M; Bonivento, W; Booth, P S L; Bosio, C; Botner, O; Boudinov, E; Bouquet, B; Bourdarios, C; Bowcock, T J V; Bozzo, M; Branchini, P; Brand, K D; Brenke, T; Brenner, R A; Bricman, C; Brown, R C A; Brückman, P; Brunet, J M; Bugge, L; Buran, T; Burgsmüller, T; Buschmann, P; Cabrera, S; Caccia, M; Calvi, M; Camacho-Rozas, A J; Camporesi, T; Canale, V; Canepa, M; Cankocak, K; Cao, F; Carena, F; Carroll, L; Caso, Carlo; Castillo-Gimenez, M V; Cattai, A; Cavallo, F R; Chabaud, V; Charpentier, P; Chaussard, L; Checchia, P; Chelkov, G A; Chen, M; Chierici, R; Chliapnikov, P V; Chochula, P; Chorowicz, V; Chudoba, J; Cindro, V; Collins, P; Contri, R; Cortina, E; Cosme, G; Cossutti, F; Cowell, J H; Crawley, H B; Crennell, D J; Crosetti, G; Cuevas-Maestro, J; Czellar, S; Dahl-Jensen, Erik; Dahm, J; D'Almagne, B; Dam, M; Damgaard, G; Dauncey, P D; Davenport, Martyn; Da Silva, W; Defoix, C; Deghorain, A; Della Ricca, G; Delpierre, P A; Demaria, N; De Angelis, A; de Boer, Wim; De Brabandere, S; De Clercq, C; La Vaissière, C de; De Lotto, B; De Min, A; De Paula, L S; De Saint-Jean, C; Dijkstra, H; Di Ciaccio, Lucia; Di Diodato, A; Djama, F; Djannati, A; Dolbeau, J; Doroba, K; Dracos, M; Drees, J; Drees, K A; Dris, M; Durand, J D; Edsall, D M; Ehret, R; Eigen, G; Ekelöf, T J C; Ekspong, Gösta; Elsing, M; Engel, J P; Erzen, B; Espirito-Santo, M C; Falk, E; Fassouliotis, D; Feindt, Michael; Ferrer, A; Fichet, S; Filippas-Tassos, A; Firestone, A; Fischer, P A; Föth, H; Fokitis, E; Fontanelli, F; Formenti, F; Franek, B J; Frenkiel, P; Fries, D E C; Frodesen, A G; Frühwirth, R; Fulda-Quenzer, F; Fuster, J A; Galloni, A; Gamba, D; Gandelman, M; García, C; García, J; Gaspar, C; Gasparini, U; Gavillet, P; Gazis, E N; Gelé, D; Gerber, J P; Gerdyukov, L N; Gokieli, R; Golob, B; Gopal, Gian P; Gorn, L; Górski, M; Guz, Yu; Gracco, Valerio; Graziani, E; Green, C; Grefrath, A; Gris, P; Grosdidier, G; Grzelak, K; Gumenyuk, S A; Gunnarsson, P; Günther, M; Guy, J; Hahn, F; Hahn, S; Hajduk, Z; Hallgren, A; Hamacher, K; Harris, F J; Hedberg, V; Henriques, R P; Hernández, J J; Herquet, P; Herr, H; Hessing, T L; Heuser, J M; Higón, E; Hilke, Hans Jürgen; Hill, T S; Holmgren, S O; Holt, P J; Holthuizen, D J; Hoorelbeke, S; Houlden, M A; Hrubec, Josef; Huet, K; Hultqvist, K; Jackson, J N; Jacobsson, R; Jalocha, P; Janik, R; Jarlskog, C; Jarlskog, G; Jarry, P; Jean-Marie, B; Johansson, E K; Jönsson, L B; Jönsson, P E; Joram, Christian; Juillot, P; Kaiser, M; Kapusta, F; Karafasoulis, K; Karlsson, M; Karvelas, E; Katargin, A; Katsanevas, S; Katsoufis, E C; Keränen, R; Khokhlov, Yu A; Khomenko, B A; Khovanskii, N N; King, B J; Kjaer, N J; Klapp, O; Klein, H; Klovning, A; Kluit, P M; Köne, B; Kokkinias, P; Koratzinos, M; Korcyl, K; Kostyukhin, V; Kourkoumelis, C; Kuznetsov, O; Krammer, Manfred; Kreuter, C; Kronkvist, I J; Krumshtein, Z; Krupinski, W; Kubinec, P; Kucewicz, W; Kurvinen, K L; Lacasta, C; Laktineh, I; Lamsa, J; Lanceri, L; Lane, D W; Langefeld, P; Lapin, V; Laugier, J P; Lauhakangas, R; Leder, Gerhard; Ledroit, F; Lefébure, V; Legan, C K; Leitner, R; Lemonne, J; Lenzen, Georg; Lepeltier, V; Lesiak, T; Libby, J; Liko, D; Lindner, R; Lipniacka, A; Lippi, I; Lörstad, B; Loken, J G; López, J M; Loukas, D; Lutz, P; Lyons, L; MacNaughton, J N; Maehlum, G; Mahon, J R; Malmgren, T G M; Malychev, V; Mandl, F; Marco, J; Marco, R P; Maréchal, B; Margoni, M; Marin, J C; Mariotti, C; Markou, A; Martínez-Rivero, C; Martínez-Vidal, F; Martí i García, S; Masik, J; Matorras, F; Matteuzzi, C; Matthiae, Giorgio; Mazzucato, M; McCubbin, M L; McKay, R; McNulty, R; Medbo, J; Merk, M; Meroni, C; Meyer, S; Meyer, W T; Michelotto, M; Migliore, E; Mirabito, L; Mitaroff, Winfried A; Mjörnmark, U; Moa, T; Møller, R; Mönig, K; Monge, M R; Morettini, P; Müller, H; Münich, K; Mulders, M; Mundim, L M; Murray, W J; Muryn, B; Myatt, Gerald; Naraghi, F; Navarria, Francesco Luigi; Navas, S; Nawrocki, K; Negri, P; Neumann, W; Neumeister, N; Nicolaidou, R; Nielsen, B S; Nieuwenhuizen, M; Nikolaenko, V; Niss, P; Nomerotski, A; Normand, Ainsley; Novák, M; Oberschulte-Beckmann, W; Obraztsov, V F; Olshevskii, A G; Onofre, A; Orava, Risto; Österberg, K; Ouraou, A; Paganini, P; Paganoni, M; Pagès, P; Pain, R; Palka, H; Papadopoulou, T D; Papageorgiou, K; Pape, L; Parkes, C; Parodi, F; Passeri, A; Pegoraro, M; Peralta, L; Pernicka, Manfred; Perrotta, A; Petridou, C; Petrolini, A; Petrovykh, M; Phillips, H T; Piana, G; Pierre, F; Pimenta, M; Podobnik, T; Podobrin, O; Pol, M E; Polok, G; Poropat, P; Pozdnyakov, V; Privitera, P; Pukhaeva, N; Pullia, Antonio; Radojicic, D; Ragazzi, S; Rahmani, H; Rames, J; Ratoff, P N; Read, A L; Reale, M; Rebecchi, P; Redaelli, N G; Regler, Meinhard; Reid, D; Reinhardt, R; Renton, P B; Resvanis, L K; Richard, F; Richardson, J; Rídky, J; Rinaudo, G; Ripp, I; Romero, A; Roncagliolo, I; Ronchese, P; Roos, L; Rosenberg, E I; Roudeau, Patrick; Rovelli, T; Rückstuhl, W; Ruhlmann-Kleider, V; Ruiz, A; Rybicki, K; Rybin, A; Saarikko, H; Sacquin, Yu; Sadovskii, A; Sahr, O; Sajot, G; Salt, J; Sánchez, J; Sannino, M; Schimmelpfennig, M; Schneider, H; Schwickerath, U; Schyns, M A E; Sciolla, G; Scuri, F; Seager, P; Sedykh, Yu; Segar, A M; Seitz, A; Sekulin, R L; Serbelloni, L; Shellard, R C; Siegrist, P; Silvestre, R; Simonetti, S; Simonetto, F; Sissakian, A N; Sitár, B; Skaali, T B; Smadja, G; Smirnov, N; Smirnova, O G; Smith, G R; Sosnowski, R; Souza-Santos, D; Spassoff, Tz; Spiriti, E; Sponholz, P; Squarcia, S; Stampfer, D; Stanescu, C; Stanic, S; Stapnes, Steinar; Stavitski, I; Stevenson, K; Stocchi, A; Strauss, J; Strub, R; Stugu, B; Szczekowski, M; Szeptycka, M; Tabarelli de Fatis, T; Tavernet, J P; Chikilev, O G; Thomas, J; Tilquin, A; Timmermans, J; Tkatchev, L G; Todorov, T; Todorova, S; Toet, D Z; Tomaradze, A G; Tomé, B; Tonazzo, A; Tortora, L; Tranströmer, G; Treille, D; Tristram, G; Trombini, A; Troncon, C; Tsirou, A L; Turluer, M L; Tyapkin, I A; Tyndel, M; Tzamarias, S; Überschär, B; Ullaland, O; Uvarov, V; Valenti, G; Vallazza, E; Van der Velde, C; van Apeldoorn, G W; van Dam, P; Van Doninck, W K; Van Eldik, J; Van Lysebetten, A; Vassilopoulos, N; Vegni, G; Ventura, L; Venus, W A; Verbeure, F; Verlato, M; Vertogradov, L S; Vilanova, D; Vincent, P; Vitale, L; Vlasov, E; Vodopyanov, A S; Vrba, V; Wahlen, H; Walck, C; Weierstall, M; Weilhammer, Peter; Weiser, C; Wetherell, Alan M; Wicke, D; Wickens, J H; Wielers, M; Wilkinson, G R; Williams, W S C; Winter, M; Witek, M; Wlodek, T; Woschnagg, K; Yip, K; Yushchenko, O P; Zach, F; Zaitsev, A; Zalewska-Bak, A; Zalewski, Piotr; Zavrtanik, D; Zevgolatakos, E; Zimin, N I; Zito, M; Zontar, D; Zucchelli, G C; Zumerle, G

    1997-01-01

    A sample of about 1.4 million hadronic \\z decays, selected among the data recorded by the DELPHI detector at LEP during 1994, was used to measure for the first time the momentum spectra of \\kp, \\ko, \\p, \\l and their antiparticles in gluon and quark jets. As observed for inclusive charged particles, the production spectra of identified particles were found to be softer in gluon jets than in quark jets, with a higher total multiplicity.

  20. Identifying Tracks Duplicates via Neural Network

    CERN Document Server

    Sunjerga, Antonio; CERN. Geneva. EP Department

    2017-01-01

    The goal of the project is to study feasibility of state of the art machine learning techniques in track reconstruction. Machine learning techniques provide promising ways to speed up the pattern recognition of tracks by adding more intelligence in the algorithms. Implementation of neural network to process of track duplicates identifying will be discussed. Different approaches are shown and results are compared to method that is currently in use.

  1. Identifying web usage behavior of bank customers

    Science.gov (United States)

    Araya, Sandro; Silva, Mariano; Weber, Richard

    2002-03-01

    The bank Banco Credito e Inversiones (BCI) started its virtual bank in 1996 and its registered customers perform currently more than 10,000 Internet transactions daily, which typically cause les than 10% of traditional transaction costs. Since most of the customers are still not registered for online banking, one of the goals of the virtual bank is to increase then umber of registered customers. Objective of the presented work was to identify customers who are likely to perform online banking but still do not use this medium for their transactions. This objective has been reached by determining profiles of registered customers who perform many transactions online. Based on these profiles the bank's Data Warehouse is explored for twins of these heavy users that are still not registered for online banking. We applied clustering in order to group the registered customers into five classes. One of these classes contained almost 30% of all registered customers and could clearly be identified as class of heavy users. Next a neural network assigned online customers to the previously found five classes. Applying the network trained on online customers to all the bank customers identified twins of heavy users that, however had not performed online transactions so far. A mailing to these candidates informing about the advantages of online banking doubled the number of registrations compared to previous campaigns.

  2. Identifying Broadband Rotational Spectra with Neural Networks

    Science.gov (United States)

    Zaleski, Daniel P.; Prozument, Kirill

    2017-06-01

    A typical broadband rotational spectrum may contain several thousand observable transitions, spanning many species. Identifying the individual spectra, particularly when the dynamic range reaches 1,000:1 or even 10,000:1, can be challenging. One approach is to apply automated fitting routines. In this approach, combinations of 3 transitions can be created to form a "triple", which allows fitting of the A, B, and C rotational constants in a Watson-type Hamiltonian. On a standard desktop computer, with a target molecule of interest, a typical AUTOFIT routine takes 2-12 hours depending on the spectral density. A new approach is to utilize machine learning to train a computer to recognize the patterns (frequency spacing and relative intensities) inherit in rotational spectra and to identify the individual spectra in a raw broadband rotational spectrum. Here, recurrent neural networks have been trained to identify different types of rotational spectra and classify them accordingly. Furthermore, early results in applying convolutional neural networks for spectral object recognition in broadband rotational spectra appear promising. Perez et al. "Broadband Fourier transform rotational spectroscopy for structure determination: The water heptamer." Chem. Phys. Lett., 2013, 571, 1-15. Seifert et al. "AUTOFIT, an Automated Fitting Tool for Broadband Rotational Spectra, and Applications to 1-Hexanal." J. Mol. Spectrosc., 2015, 312, 13-21. Bishop. "Neural networks for pattern recognition." Oxford university press, 1995.

  3. Metabolites of cannabidiol identified in human urine.

    Science.gov (United States)

    Harvey, D J; Mechoulam, R

    1990-03-01

    1. Urine from a dystonic patient treated with cannabidiol (CBD) was examined by g.l.c.-mass spectrometry for CBD metabolites. Metabolites were identified as their trimethylsilyl (TMS), [2H9]TMS, and methyl ester/TMS derivatives and as the TMS derivatives of the product of lithium aluminium deuteride reduction. 2. Thirty-three metabolites were identified in addition to unmetabolized CBD, and a further four metabolites were partially characterized. 3. The major metabolic route was hydroxylation and oxidation at C-7 followed by further hydroxylation in the pentyl and propenyl groups to give 1"-, 2"-, 3"-, 4"- and 10-hydroxy derivatives of CBD-7-oic acid. Other metabolites, mainly acids, were formed by beta-oxidation and related biotransformations from the pentyl side-chain and these were also hydroxylated at C-6 or C-7. The major oxidized metabolite was CBD-7-oic acid containing a hydroxyethyl side-chain. 4. Two 8,9-dihydroxy compounds, presumably derived from the corresponding epoxide were identified. 5. Also present were several cyclized cannabinoids including delta-6- and delta-1-tetrahydrocannabinol and cannabinol. 6. This is the first metabolic study of CBD in humans; most observed metabolic routes were typical of those found for CBD and related cannabinoids in other species.

  4. Bisexual Phenomena Among Gay-Identified Men.

    Science.gov (United States)

    Semon, Theodore L; Hsu, Kevin J; Rosenthal, A M; Bailey, J Michael

    2017-01-01

    A high proportion of self-identified gay men exhibit aspects of bisexuality during their lives. Some identify as bisexual before later identifying as gay; this has been called transitional bisexuality. Although many gay men report no attraction to women-or even sexual disgust toward them-others report some slight attraction to women. The latter have been studied as mostly homosexual men. We studied men with and without a history of transitional bisexuality, as well as mostly homosexual (i.e., those with Kinsey scores of 5) and completely homosexual (i.e., those with Kinsey scores of 6) men with respect to their sexual history with women, their current self-reported sexual arousal and disgust toward women and men, and their patterns of genital sexual arousal to female and male stimuli. Gay men with a history of transitional bisexuality generally lacked current sexual attraction and sexual arousal to women, compared with other gay men. Thus, transitional bisexuality among future gay men is mostly a matter of transitional bisexual identification. In contrast, mostly homosexual men showed statistically significant increases in genital arousal to female stimuli, compared with completely homosexual men.

  5. Persistent Identifiers, Discoverability and Open Science (Communication)

    Science.gov (United States)

    Murphy, Fiona; Lehnert, Kerstin; Hanson, Brooks

    2016-04-01

    Early in 2016, the American Geophysical Union announced it was incorporating ORCIDs into its submission workflows. This was accompanied by a strong statement supporting the use of other persistent identifiers - such as IGSNs, and the CrossRef open registry 'funding data'. This was partly in response to funders' desire to track and manage their outputs. However the more compelling argument, and the reason why the AGU has also signed up to the Center for Open Science's Transparency and Openness Promotion (TOP) Guidelines (http://cos.io/top), is that ultimately science and scientists will be the richer for these initiatives due to increased opportunities for interoperability, reproduceability and accreditation. The AGU has appealed to the wider community to engage with these initiatives, recognising that - unlike the introduction of Digital Object Identifiers (DOIs) for articles by CrossRef - full, enriched use of persistent identifiers throughout the scientific process requires buy-in from a range of scholarly communications stakeholders. At the same time, across the general research landscape, initiatives such as Project CRediT (contributor roles taxonomy), Publons (reviewer acknowledgements) and the forthcoming CrossRef DOI Event Tracker are contributing to our understanding and accreditation of contributions and impact. More specifically for earth science and scientists, the cross-functional Coalition for Publishing Data in the Earth and Space Sciences (COPDESS) was formed in October 2014 and is working to 'provide an organizational framework for Earth and space science publishers and data facilities to jointly implement and promote common policies and procedures for the publication and citation of data across Earth Science journals'. Clearly, the judicious integration of standards, registries and persistent identifiers such as ORCIDs and International Geo Sample Numbers (IGSNs) to the research and research output processes is key to the success of this venture

  6. Body linear traits for identifying prolific goats

    Directory of Open Access Journals (Sweden)

    Avijit Haldar

    2014-12-01

    Full Text Available Aim: The present study was conducted on prolific goat breed to identify body linear type traits that might be associated with prolificacy trait in goats. Materials and Methods: Two-stage stratified random sample survey based data were collected from 1427 non-pregnant goats with the history of single, twin and triplet litter sizes (LZ between January 2008 to February 2011 for 3 years in 68 villages located in East and North East India. Data on sixteen body linear traits were analyzed using logistic regression model to do the step-wise selection for identifying the body linear traits that could determine LZ. An average value for each identified body linear trait was determined for classifying the goats into three categories: Goats having the history of single LZ, goats having the history of twin LZ and goats having the history of triplet LZ. Results: The LZ proportions for single, twin and triplet, were 29.50, 59.14 and 11.36%, respectively, with the prolificacy rate of 181.85% in Indian Black Bengal goats. A total of eight body linear traits that could determine LZ in prolific goats were identified. Heart girth (HG measurement (>60.90 cm, paunch girth (PG (>70.22 cm, wither height (WH (>49.75 cm, neck length (>21.45 cm, ear length (>12.80 cm and distance between trochanter major (DTM bones (>12.28 cm, pelvic triangle area (PTA (>572.25 cm2 and clearance at udder (CU (>23.16 cm showed an increase likelihood of multiple LZ when compared to single LZ. Further, HG measurement (>62.29 cm, WH (>50.54 cm, PG (>71.85 cm and ear length (>13.00 cm, neck length (>22.01 cm, PTA (>589.64 cm2, CU (>23.20 cm and DTM bones (>12.47 cm were associated with increased likelihood of triplet LZ, when compared with that of twin LZ. Conclusion: HG measurement was the best discriminating factor, while PG, neck length, DTM bones, CU, PTA, WH and ear length measurements were other important factors that could be used for identifying prolific goats to achieve economic

  7. Identifying novel drug indications through automated reasoning.

    Directory of Open Access Journals (Sweden)

    Luis Tari

    Full Text Available With the large amount of pharmacological and biological knowledge available in literature, finding novel drug indications for existing drugs using in silico approaches has become increasingly feasible. Typical literature-based approaches generate new hypotheses in the form of protein-protein interactions networks by means of linking concepts based on their cooccurrences within abstracts. However, this kind of approaches tends to generate too many hypotheses, and identifying new drug indications from large networks can be a time-consuming process.In this work, we developed a method that acquires the necessary facts from literature and knowledge bases, and identifies new drug indications through automated reasoning. This is achieved by encoding the molecular effects caused by drug-target interactions and links to various diseases and drug mechanism as domain knowledge in AnsProlog, a declarative language that is useful for automated reasoning, including reasoning with incomplete information. Unlike other literature-based approaches, our approach is more fine-grained, especially in identifying indirect relationships for drug indications.To evaluate the capability of our approach in inferring novel drug indications, we applied our method to 943 drugs from DrugBank and asked if any of these drugs have potential anti-cancer activities based on information on their targets and molecular interaction types alone. A total of 507 drugs were found to have the potential to be used for cancer treatments. Among the potential anti-cancer drugs, 67 out of 81 drugs (a recall of 82.7% are indeed known cancer drugs. In addition, 144 out of 289 drugs (a recall of 49.8% are non-cancer drugs that are currently tested in clinical trials for cancer treatments. These results suggest that our method is able to infer drug indications (original or alternative based on their molecular targets and interactions alone and has the potential to discover novel drug indications for

  8. Identifying single copy orthologs in Metazoa.

    Directory of Open Access Journals (Sweden)

    Christopher J Creevey

    2011-12-01

    Full Text Available The identification of single copy (1-to-1 orthologs in any group of organisms is important for functional classification and phylogenetic studies. The Metazoa are no exception, but only recently has there been a wide-enough distribution of taxa with sufficiently high quality sequenced genomes to gain confidence in the wide-spread single copy status of a gene.Here, we present a phylogenetic approach for identifying overlooked single copy orthologs from multigene families and apply it to the Metazoa. Using 18 sequenced metazoan genomes of high quality we identified a robust set of 1,126 orthologous groups that have been retained in single copy since the last common ancestor of Metazoa. We found that the use of the phylogenetic procedure increased the number of single copy orthologs found by over a third more than standard taxon-count approaches. The orthologs represented a wide range of functional categories, expression profiles and levels of divergence.To demonstrate the value of our set of single copy orthologs, we used them to assess the completeness of 24 currently published metazoan genomes and 62 EST datasets. We found that the annotated genes in published genomes vary in coverage from 79% (Ciona intestinalis to 99.8% (human with an average of 92%, suggesting a value for the underlying error rate in genome annotation, and a strategy for identifying single copy orthologs in larger datasets. In contrast, the vast majority of EST datasets with no corresponding genome sequence available are largely under-sampled and probably do not accurately represent the actual genomic complement of the organisms from which they are derived.

  9. Method of identifying defective particle coatings

    Science.gov (United States)

    Cohen, Mark E.; Whiting, Carlton D.

    1986-01-01

    A method for identifying coated particles having defective coatings desig to retain therewithin a build-up of gaseous materials including: (a) Pulling a vacuum on the particles; (b) Backfilling the particles at atmospheric pressure with a liquid capable of wetting the exterior surface of the coated particles, said liquid being a compound which includes an element having an atomic number higher than the highest atomic number of any element in the composition which forms the exterior surface of the particle coating; (c) Drying the particles; and (d) Radiographing the particles. By television monitoring, examination of the radiographs is substantially enhanced.

  10. [Identifying children at risk for cardiorespiratory arrest].

    Science.gov (United States)

    Carrillo Alvarez, A; Martínez Gutiérrez, A; Salvat Germán, F

    2004-08-01

    Cardiorespiratory arrest in children with severe disease does not usually present suddenly or unexpectedly but is often the result of a progressive deterioration of respiratory and/or circulatory function. Before failure of these functions occurs, there is a series of clinical signs that serve as a warning. Health professionals should not only evaluate clinical signs of respiratory and/or circulatory insufficiency but should also be able to identify these warning signs as early as possible, preferably in the compensation phase, given that the possibility that this process can be reversed by therapeutic measures decreases as the process progresses.

  11. Identifying opportunities in online-communities

    DEFF Research Database (Denmark)

    Hienerth, C.; Lettl, Christopher

    how this phenomenon - as manifested in user communities - can be used to derive deeper insights into the prominent phases of opportunity identification, evaluation and exploitation. We also outline how user communities create new avenues for empirical research on these early entrepreneurial processes......Previous research has identified innovation as a crucial prerequisite for early entrepreneurial processes. However, the nature of how innovations are developed is changing dramatically, as it is becoming increasingly open, collaborative and democratized. This paper demonstrates in conceptual terms....... Based on our analysis, we develop a set of hypotheses on how processes in user communities affect the outcome of entrepreneurial activities....

  12. Identifying variables that influence manufacturing product quality

    Directory of Open Access Journals (Sweden)

    Marek Krynke

    2014-10-01

    Full Text Available In the article a risk analysis of the production process of selected products in a plant producing votive candles was conducted. The Pareto-Lorenz diagram and FMEA method were used which indicated the most important areas affecting the production of selected elements of candles. The synthesis of intangible factors affecting production in the audited company was also carried out with particular emphasis on the operation of the production system. The factors determining the validity of studies was examined, describing the principle of BOST 14 Toyota management. The most important areas of the company were identified, positively affecting the production process.

  13. Identifying biomass fuel shortages in Sri Lanka

    Energy Technology Data Exchange (ETDEWEB)

    Howes, Michael (Sussex Univ., Brighton (UK). Inst. of Development Studies)

    1989-01-01

    This paper analyses data from the Sri Lankan Forestry Master Plan and other sources, to explore the causes of biomass shortages, and to identify the areas where interventions are likely to have most impact. Five districts, concentrated in the wet lowland and hill country zones, are found to be in overall biomass fuel deficit whilst in a further five, which include dry zone locations, fuelwood consumption exceeds potential supply, Within the area of overall deficit, poorer urban groups and rural families with no home gardens - who together comprise 15% of all households nationally - are affected most severely. Another 10% of households are likely to suffer to a lesser extent. (author).

  14. EVA: Visual Analytics to Identify Fraudulent Events.

    Science.gov (United States)

    Leite, Roger A; Gschwandtner, Theresia; Miksch, Silvia; Kriglstein, Simone; Pohl, Margit; Gstrein, Erich; Kuntner, Johannes

    2018-01-01

    Financial institutions are interested in ensuring security and quality for their customers. Banks, for instance, need to identify and stop harmful transactions in a timely manner. In order to detect fraudulent operations, data mining techniques and customer profile analysis are commonly used. However, these approaches are not supported by Visual Analytics techniques yet. Visual Analytics techniques have potential to considerably enhance the knowledge discovery process and increase the detection and prediction accuracy of financial fraud detection systems. Thus, we propose EVA, a Visual Analytics approach for supporting fraud investigation, fine-tuning fraud detection algorithms, and thus, reducing false positive alarms.

  15. Identifying Phase Space Boundaries with Voronoi Tessellations

    CERN Document Server

    Debnath, Dipsikha; Kilic, Can; Kim, Doojin; Matchev, Konstantin T.; Yang, Yuan-Pao

    2016-11-24

    Determining the masses of new physics particles appearing in decay chains is an important and longstanding problem in high energy phenomenology. Recently it has been shown that these mass measurements can be improved by utilizing the boundary of the allowed region in the fully differentiable phase space in its full dimensionality. Here we show that the practical challenge of identifying this boundary can be solved using techniques based on the geometric properties of the cells resulting from Voronoi tessellations of the relevant data. The robust detection of such phase space boundaries in the data could also be used to corroborate a new physics discovery based on a cut-and-count analysis.

  16. Identifying QCD Transition Using Deep Learning

    Science.gov (United States)

    Zhou, Kai; Pang, Long-gang; Su, Nan; Petersen, Hannah; Stoecker, Horst; Wang, Xin-Nian

    2018-02-01

    In this proceeding we review our recent work using supervised learning with a deep convolutional neural network (CNN) to identify the QCD equation of state (EoS) employed in hydrodynamic modeling of heavy-ion collisions given only final-state particle spectra ρ(pT, V). We showed that there is a traceable encoder of the dynamical information from phase structure (EoS) that survives the evolution and exists in the final snapshot, which enables the trained CNN to act as an effective "EoS-meter" in detecting the nature of the QCD transition.

  17. Identifying MMORPG Bots: A Traffic Analysis Approach

    Directory of Open Access Journals (Sweden)

    Wen-Chin Chen

    2008-11-01

    Full Text Available Massively multiplayer online role playing games (MMORPGs have become extremely popular among network gamers. Despite their success, one of MMORPG's greatest challenges is the increasing use of game bots, that is, autoplaying game clients. The use of game bots is considered unsportsmanlike and is therefore forbidden. To keep games in order, game police, played by actual human players, often patrol game zones and question suspicious players. This practice, however, is labor-intensive and ineffective. To address this problem, we analyze the traffic generated by human players versus game bots and propose general solutions to identify game bots. Taking Ragnarok Online as our subject, we study the traffic generated by human players and game bots. We find that their traffic is distinguishable by 1 the regularity in the release time of client commands, 2 the trend and magnitude of traffic burstiness in multiple time scales, and 3 the sensitivity to different network conditions. Based on these findings, we propose four strategies and two ensemble schemes to identify bots. Finally, we discuss the robustness of the proposed methods against countermeasures of bot developers, and consider a number of possible ways to manage the increasingly serious bot problem.

  18. Identifying dependability requirements for space software systems

    Directory of Open Access Journals (Sweden)

    Edgar Toshiro Yano

    2010-09-01

    Full Text Available Computer systems are increasingly used in space, whether in launch vehicles, satellites, ground support and payload systems. Software applications used in these systems have become more complex, mainly due to the high number of features to be met, thus contributing to a greater probability of hazards related to software faults. Therefore, it is fundamental that the specification activity of requirements have a decisive role in the effort of obtaining systems with high quality and safety standards. In critical systems like the embedded software of the Brazilian Satellite Launcher, ambiguity, non-completeness, and lack of good requirements can cause serious accidents with economic, material and human losses. One way to assure quality with safety, reliability and other dependability attributes may be the use of safety analysis techniques during the initial phases of the project in order to identify the most adequate dependability requirements to minimize possible fault or failure occurrences during the subsequent phases. This paper presents a structured software dependability requirements analysis process that uses system software requirement specifications and traditional safety analysis techniques. The main goal of the process is to help to identify a set of essential software dependability requirements which can be added to the software requirement previously specified for the system. The final results are more complete, consistent, and reliable specifications.

  19. Identifying Bitcoin users by transaction behavior

    Science.gov (United States)

    Monaco, John V.

    2015-05-01

    Digital currencies, such as Bitcoin, offer convenience and security to criminals operating in the black marketplace. Some Bitcoin marketplaces, such as Silk Road, even claim anonymity. This claim contradicts the findings in this work, where long term transactional behavior is used to identify and verify account holders. Transaction timestamps and network properties observed over time contribute to this finding. The timestamp of each transaction is the result of many factors: the desire purchase an item, daily schedule and activities, as well as hardware and network latency. Dynamic network properties of the transaction, such as coin flow and the number of edge outputs and inputs, contribute further to reveal account identity. In this paper, we propose a novel methodology for identifying and verifying Bitcoin users based on the observation of Bitcoin transactions over time. The behavior we attempt to quantify roughly occurs in the social band of Newell's time scale. A subset of the Blockchain 230686 is taken, selecting users that initiated between 100 and 1000 unique transactions per month for at least 6 different months. This dataset shows evidence of being nonrandom and nonlinear, thus a dynamical systems approach is taken. Classification and authentication accuracies are obtained under various representations of the monthly Bitcoin samples: outgoing transactions, as well as both outgoing and incoming transactions are considered, along with the timing and dynamic network properties of transaction sequences. The most appropriate representations of monthly Bitcoin samples are proposed. Results show an inherent lack of anonymity by exploiting patterns in long-term transactional behavior.

  20. Identifying, meeting, and assessing customer expectations

    International Nuclear Information System (INIS)

    Danner, T.A.

    1995-01-01

    Maintaining proficiency in carrying out mission goals is fundamental to the success of any organization. The definitive mission of the Waste Management and Remedial Action Division (WMRAD) of Oak Ridge National Laboratory (ORNL) is open-quotes to conduct waste management activities in a compliant, publicly acceptable, technically sound, and cost-efficient mannerclose quotes. In order to effectively fulfill this mission, must meet or exceed several standards in respect to our customers. These include: (1) identifying current and future customer expectations; (2) managing our relationships with our customers; (3) ensuring our commitment to our customers; and (4) measuring our success m customer satisfaction. Our customers have a great variety of requirements and expectations. Many of these are in the form of local, state, and federal regulations and environmental standards. Others are brought to our attention through inquires made to the Department of Energy (DOE).Consumer surveys have proven to be effective tools which have been used to make improvements, enhance certain program elements, and identify beneficial areas in already existing programs. In addition, national working groups, technology transfer meetings, and manager/contractor's meeting offer excellent opportunities to assess our activities

  1. Measurements with self-identifying aerosols

    International Nuclear Information System (INIS)

    Kyle, T.; Schuster, B.G.

    1978-01-01

    The use of modern single particle detection of aerosols has made it possible to test multiple HEPA filter systems. Problems have been encountered in such tests with the background aerosol on the downstream side of the filters. Since the ducts are maintained at a negative pressure, ambient aerosols leak into the ducts and provide concentrations of particles which are comparable to the number of particles of the test aerosol passing through the filters. The background count creates an upper limit to the protection factor which can be measured. This limitation can be overcome by the use of an identifiable aerosol. The most direct method of identifying an aerosol is to use fluorescent particles, which has been done in the past. In the present case, the fluorescence of the individual particle is used, rather than dissolving the particles in solution to develop the fluorescence. Two systems based upon fluorescent solid or liquid particles are being developed. Both involve single particle detection and excitation by a portable helium-cadmium laser. The advantage of the solid particles system is the ability to capture the particles on a filter. The filter can then be dissolved and the number of particles counted and sized, since the particles do not dissolve. This also permits the use of greater sample flow rates than is possible with a real time system

  2. Identifying Functional Cysteine Residues in the Mitochondria.

    Science.gov (United States)

    Bak, Daniel W; Pizzagalli, Mattia D; Weerapana, Eranthie

    2017-04-21

    The mitochondria are dynamic organelles that regulate oxidative metabolism and mediate cellular redox homeostasis. Proteins within the mitochondria are exposed to large fluxes in the surrounding redox environment. In particular, cysteine residues within mitochondrial proteins sense and respond to these redox changes through oxidative modifications of the cysteine thiol group. These oxidative modifications result in a loss in cysteine reactivity, which can be monitored using cysteine-reactive chemical probes and quantitative mass spectrometry (MS). Analysis of cell lysates treated with cysteine-reactive probes enable the identification of hundreds of cysteine residues, however, the mitochondrial proteome is poorly represented (proteins and suppression of mitochondrial peptide MS signals by highly abundant cytosolic peptides. Here, we apply a mitochondrial isolation and purification protocol to substantially increase coverage of the mitochondrial cysteine proteome. Over 1500 cysteine residues from ∼450 mitochondrial proteins were identified, thereby enabling interrogation of an unprecedented number of mitochondrial cysteines. Specifically, these mitochondrial cysteines were ranked by reactivity to identify hyper-reactive cysteines with potential catalytic and regulatory functional roles. Furthermore, analyses of mitochondria exposed to nitrosative stress revealed previously uncharacterized sites of protein S-nitrosation on mitochondrial proteins. Together, the mitochondrial cysteine enrichment strategy presented herein enables detailed characterization of protein modifications that occur within the mitochondria during (patho)physiological fluxes in the redox environment.

  3. Identifying barriers to Muslim integration in France.

    Science.gov (United States)

    Adida, Claire L; Laitin, David D; Valfort, Marie-Anne

    2010-12-28

    Is there a Muslim disadvantage in economic integration for second-generation immigrants to Europe? Previous research has failed to isolate the effect that religion may have on an immigrant family's labor market opportunities because other factors, such as country of origin or race, confound the result. This paper uses a correspondence test in the French labor market to identify and measure this religious effect. The results confirm that in the French labor market, anti-Muslim discrimination exists: a Muslim candidate is 2.5 times less likely to receive a job interview callback than is his or her Christian counterpart. A high-n survey reveals, consistent with expectations from the correspondence test, that second-generation Muslim households in France have lower income compared with matched Christian households. The paper thereby contributes to both substantive debates on the Muslim experience in Europe and methodological debates on how to measure discrimination. Following the National Academy of Sciences' 2001 recommendations on combining a variety of methodologies and applying them to real-world situations, this research identifies, measures, and infers consequences of discrimination based on religious affiliation, controlling for potentially confounding factors, such as race and country of origin.

  4. ABCB5 Identifies Immunoregulatory Dermal Cells

    Directory of Open Access Journals (Sweden)

    Tobias Schatton

    2015-09-01

    Full Text Available Cell-based strategies represent a new frontier in the treatment of immune-mediated disorders. However, the paucity of markers for isolation of molecularly defined immunomodulatory cell populations poses a barrier to this field. Here, we show that ATP-binding cassette member B5 (ABCB5 identifies dermal immunoregulatory cells (DIRCs capable of exerting therapeutic immunoregulatory functions through engagement of programmed cell death 1 (PD-1. Purified Abcb5+ DIRCs suppressed T cell proliferation, evaded immune rejection, homed to recipient immune tissues, and induced Tregs in vivo. In fully major-histocompatibility-complex-mismatched cardiac allotransplantation models, allogeneic DIRCs significantly prolonged allograft survival. Blockade of DIRC-expressed PD-1 reversed the inhibitory effects of DIRCs on T cell activation, inhibited DIRC-dependent Treg induction, and attenuated DIRC-induced prolongation of cardiac allograft survival, indicating that DIRC immunoregulatory function is mediated, at least in part, through PD-1. Our results identify ABCB5+ DIRCs as a distinct immunoregulatory cell population and suggest promising roles of this expandable cell subset in cellular immunotherapy.

  5. Identifying the immunomodulatory components of helminths.

    Science.gov (United States)

    Shepherd, C; Navarro, S; Wangchuk, P; Wilson, D; Daly, N L; Loukas, A

    2015-06-01

    Immunomodulatory components of helminths offer great promise as an entirely new class of biologics for the treatment of inflammatory diseases. Here, we discuss the emerging themes in helminth-driven immunomodulation in the context of therapeutic drug discovery. We broadly define the approaches that are currently applied by researchers to identify these helminth molecules, highlighting key areas of potential exploitation that have been mostly neglected thus far, notably small molecules. Finally, we propose that the investigation of immunomodulatory compounds will enable the translation of current and future research efforts into potential treatments for autoimmune and allergic diseases, while at the same time yielding new insights into the molecular interface of host-parasite biology. © 2015 John Wiley & Sons Ltd.

  6. Identifying States of a Financial Market

    Science.gov (United States)

    Münnix, Michael C.; Shimada, Takashi; Schäfer, Rudi; Leyvraz, Francois; Seligman, Thomas H.; Guhr, Thomas; Stanley, H. Eugene

    2012-09-01

    The understanding of complex systems has become a central issue because such systems exist in a wide range of scientific disciplines. We here focus on financial markets as an example of a complex system. In particular we analyze financial data from the S&P 500 stocks in the 19-year period 1992-2010. We propose a definition of state for a financial market and use it to identify points of drastic change in the correlation structure. These points are mapped to occurrences of financial crises. We find that a wide variety of characteristic correlation structure patterns exist in the observation time window, and that these characteristic correlation structure patterns can be classified into several typical ``market states''. Using this classification we recognize transitions between different market states. A similarity measure we develop thus affords means of understanding changes in states and of recognizing developments not previously seen.

  7. Identifying states of a financial market.

    Science.gov (United States)

    Münnix, Michael C; Shimada, Takashi; Schäfer, Rudi; Leyvraz, Francois; Seligman, Thomas H; Guhr, Thomas; Stanley, H Eugene

    2012-01-01

    The understanding of complex systems has become a central issue because such systems exist in a wide range of scientific disciplines. We here focus on financial markets as an example of a complex system. In particular we analyze financial data from the S&P 500 stocks in the 19-year period 1992-2010. We propose a definition of state for a financial market and use it to identify points of drastic change in the correlation structure. These points are mapped to occurrences of financial crises. We find that a wide variety of characteristic correlation structure patterns exist in the observation time window, and that these characteristic correlation structure patterns can be classified into several typical "market states". Using this classification we recognize transitions between different market states. A similarity measure we develop thus affords means of understanding changes in states and of recognizing developments not previously seen.

  8. Machine learning for identifying botnet network traffic

    DEFF Research Database (Denmark)

    Stevanovic, Matija; Pedersen, Jens Myrup

    2013-01-01

    . Due to promise of non-invasive and resilient detection, botnet detection based on network traffic analysis has drawn a special attention of the research community. Furthermore, many authors have turned their attention to the use of machine learning algorithms as the mean of inferring botnet......-related knowledge from the monitored traffic. This paper presents a review of contemporary botnet detection methods that use machine learning as a tool of identifying botnet-related traffic. The main goal of the paper is to provide a comprehensive overview on the field by summarizing current scientific efforts....... The contribution of the paper is three-fold. First, the paper provides a detailed insight on the existing detection methods by investigating which bot-related heuristic were assumed by the detection systems and how different machine learning techniques were adapted in order to capture botnet-related knowledge...

  9. Identifying modular relations in complex brain networks

    DEFF Research Database (Denmark)

    Andersen, Kasper Winther; Mørup, Morten; Siebner, Hartwig

    2012-01-01

    and obtains comparable reproducibility and predictability. For resting state functional magnetic resonance imaging data from 30 healthy controls the IRM model is also superior to the two simpler alternatives, suggesting that brain networks indeed exhibit universal complex relational structure......We evaluate the infinite relational model (IRM) against two simpler alternative nonparametric Bayesian models for identifying structures in multi subject brain networks. The models are evaluated for their ability to predict new data and infer reproducible structures. Prediction and reproducibility...... are measured within the data driven NPAIRS split-half framework. Using synthetic data drawn from each of the generative models we show that the IRM model outperforms the two competing models when data contain relational structure. For data drawn from the other two simpler models the IRM does not overfit...

  10. Identifying Multiquark Hadrons from Heavy Ion Collisions

    International Nuclear Information System (INIS)

    Cho, Sungtae; Furumoto, Takenori; Yazaki, Koichi; Hyodo, Tetsuo; Jido, Daisuke; Ohnishi, Akira; Ko, Che Ming; Lee, Su Houng; Nielsen, Marina; Sekihara, Takayasu; Yasui, Shigehiro

    2011-01-01

    Identifying hadronic molecular states and/or hadrons with multiquark components either with or without exotic quantum numbers is a long-standing challenge in hadronic physics. We suggest that studying the production of these hadrons in relativistic heavy ion collisions offers a promising resolution to this problem as yields of exotic hadrons are expected to be strongly affected by their structures. Using the coalescence model for hadron production, we find that, compared to the case of a nonexotic hadron with normal quark numbers, the yield of an exotic hadron is typically an order of magnitude smaller when it is a compact multiquark state and a factor of 2 or more larger when it is a loosely bound hadronic molecule. We further find that some of the newly proposed heavy exotic states could be produced and realistically measured in these experiments.

  11. Identifying people from gait pattern with accelerometers

    Science.gov (United States)

    Ailisto, Heikki J.; Lindholm, Mikko; Mantyjarvi, Jani; Vildjiounaite, Elena; Makela, Satu-Marja

    2005-03-01

    Protecting portable devices is becoming more important, not only because of the value of the devices themselves, but for the value of the data in them and their capability for transactions, including m-commerce and m-banking. An unobtrusive and natural method for identifying the carrier of portable devices is presented. The method uses acceleration signals produced by sensors embedded in the portable device. When the user carries the device, the acceleration signal is compared with the stored template signal. The method consists of finding individual steps, normalizing and averaging them, aligning them with the template and computing cross-correlation, which is used as a measure of similarity. Equal Error Rate of 6.4% is achieved in tentative experiments with 36 test subjects.

  12. Identifying Biases in Dust Source Functions

    Science.gov (United States)

    Evan, A. T.; Wang, W.; Zhao, C.

    2017-12-01

    The Sahara is the largest desert in the world and accounts for more than 50% of global dust emission. However, it is difficult to identify dust source regions as the Sahara is vastly uninhabited. In order to model North African dust, previous works have used satellite data to construct so-called dust source functions. Here we examine such dust source function using output from multi-year runs with the Weather Research and Forecasting with Chemistry (WRF-Chem) model. We find that dust source functions based on satellite data overestimate DOD in the Sahel and the western Sahara region. To eliminate the biases of the dust source function due to advection, we develop a new source function using DOD in the lowest 1 km from the model. This work suggests that dust source functions constructed with satellite retrievlas of optical depth may overestimate dust emission in the downwind regions and DOD may not be a good proxy for the source function.

  13. De-identifying an EHR Database

    DEFF Research Database (Denmark)

    Lauesen, Søren; Pantazos, Kostas; Lippert, Søren

    2011-01-01

    Abstract. Electronic health records (EHR) contain a large amount of structured data and free text. Exploring and sharing clinical data can improve healthcare and facilitate the development of medical software. However, revealing confidential information is against ethical principles and laws. We de......-identified a Danish EHR database with 437,164 patients. The goal was to generate a version with real medical records, but related to artificial persons. We developed a de-identification algorithm that uses lists of named entities, simple language analysis, and special rules. Our algorithm consists of 3 steps: collect...... of anonymity, readability and correctness (F-measure of 95%). The algorithm has to be adjusted for each culture, language and database....

  14. Identifying financial crises in real time

    Science.gov (United States)

    da Fonseca, Eder Lucio; Ferreira, Fernando F.; Muruganandam, Paulsamy; Cerdeira, Hilda A.

    2013-03-01

    Following the thermodynamic formulation of a multifractal measure that was shown to enable the detection of large fluctuations at an early stage, here we propose a new index which permits us to distinguish events like financial crises in real time. We calculate the partition function from which we can obtain thermodynamic quantities analogous to the free energy and specific heat. The index is defined as the normalized energy variation and it can be used to study the behavior of stochastic time series, such as financial market daily data. Famous financial market crashes-Black Thursday (1929), Black Monday (1987) and the subprime crisis (2008)-are identified with clear and robust results. The method is also applied to the market fluctuations of 2011. From these results it appears as if the apparent crisis of 2011 is of a different nature to the other three. We also show that the analysis has forecasting capabilities.

  15. Method of identifying features in indexed data

    Science.gov (United States)

    Jarman, Kristin H [Richland, WA; Daly, Don Simone [Richland, WA; Anderson, Kevin K [Richland, WA; Wahl, Karen L [Richland, WA

    2001-06-26

    The present invention is a method of identifying features in indexed data, especially useful for distinguishing signal from noise in data provided as a plurality of ordered pairs. Each of the plurality of ordered pairs has an index and a response. The method has the steps of: (a) providing an index window having a first window end located on a first index and extending across a plurality of indices to a second window end; (b) selecting responses corresponding to the plurality of indices within the index window and computing a measure of dispersion of the responses; and (c) comparing the measure of dispersion to a dispersion critical value. Advantages of the present invention include minimizing signal to noise ratio, signal drift, varying baseline signal and combinations thereof.

  16. Identifying driver mutations in sequenced cancer genomes

    DEFF Research Database (Denmark)

    Raphael, Benjamin J; Dobson, Jason R; Oesper, Layla

    2014-01-01

    High-throughput DNA sequencing is revolutionizing the study of cancer and enabling the measurement of the somatic mutations that drive cancer development. However, the resulting sequencing datasets are large and complex, obscuring the clinically important mutations in a background of errors, noise......, and random mutations. Here, we review computational approaches to identify somatic mutations in cancer genome sequences and to distinguish the driver mutations that are responsible for cancer from random, passenger mutations. First, we describe approaches to detect somatic mutations from high-throughput DNA...... sequencing data, particularly for tumor samples that comprise heterogeneous populations of cells. Next, we review computational approaches that aim to predict driver mutations according to their frequency of occurrence in a cohort of samples, or according to their predicted functional impact on protein...

  17. Identifying Relevant Studies in Software Engineering

    DEFF Research Database (Denmark)

    Zhang, He; Ali Babar, Muhammad; Tell, Paolo

    2011-01-01

    Context: Systematic literature review (SLR) has become an important research methodology in software engineering since the introduction of evidence-based software engineering (EBSE) in 2004. One critical step in applying this methodology is to design and execute appropriate and effective search....... Objective: The main objective of the research reported in this paper is to improve the search step of undertaking SLRs in software engineering (SE) by devising and evaluating systematic and practical approaches to identifying relevant studies in SE. Method: We have systematically selected and analytically...... serve as a supplement to the guidelines for SLRs in EBSE. We plan to further evaluate the proposed approach using a series of case studies on varying research topics in SE....

  18. Strategic planning: Identifying organization information requirements

    Energy Technology Data Exchange (ETDEWEB)

    Moise, C.S.

    1993-12-01

    Historically, information resource management has been left to the ``data processing`` arm of the organization. With technological movements away from centralized mainframe-based information processing toward distributed client/server-based information processing, almost every part of an organization is becoming more involved with the information technology itself, and certainly more involved with budgeting for the technology. However, users and buyers of information technology frequently remain dependent upon the information systems department for planning what users need and should buy. This paper reviews techniques for identifying requirements throughout an organization and structuring information resources to meet organizational needs. This will include basing information resource needs on meeting business needs, utilizing ``internal`` and ``external`` information resource planners, using information mapping, assessing information resources, and developing partnerships.

  19. High-PT Physics with Identified Particles

    Energy Technology Data Exchange (ETDEWEB)

    Fries, R.; Liu, W.

    2009-11-09

    The suppression of high-P{sub T} particles in heavy ion collisions was one of the key discoveries at the Relativistic Heavy Ion Collider. This is usually parameterized by the average rate of momentum-transfer squared to this particle, {cflx q}. Here we argue that measurements of identified particles at high P{sub T} can lead to complementary information about the medium. The leading particle of a jet can change its identity through interactions with the medium. Tracing such flavor conversions could allow us to constrain the mean free path. Here we review the basic concepts of flavor conversions and discuss applications to particle ratios and elliptic flow. We make a prediction that strangeness is enhanced at high P{sub T} at RHIC energies while its elliptic flow is suppressed.

  20. Diverse papillomaviruses identified in Weddell seals.

    Science.gov (United States)

    Smeele, Zoe E; Burns, Jennifer M; Van Doorsaler, Koenraad; Fontenele, Rafaela S; Waits, Kara; Stainton, Daisy; Shero, Michelle R; Beltran, Roxanne S; Kirkham, Amy L; Berngartt, Rachel; Kraberger, Simona; Varsani, Arvind

    2018-04-01

    Papillomaviridae is a diverse family of circular, double-stranded DNA (dsDNA) viruses that infect a broad range of mammalian, avian and fish hosts. While papillomaviruses have been characterized most extensively in humans, the study of non-human papillomaviruses has contributed greatly to our understanding of their pathogenicity and evolution. Using high-throughput sequencing approaches, we identified 7 novel papillomaviruses from vaginal swabs collected from 81 adult female Weddell seals (Leptonychotes weddellii) in the Ross Sea of Antarctica between 2014-2017. These seven papillomavirus genomes were amplified from seven individual seals, and six of the seven genomes represented novel species with distinct evolutionary lineages. This highlights the diversity of papillomaviruses among the relatively small number of Weddell seal samples tested. Viruses associated with large vertebrates are poorly studied in Antarctica, and this study adds information about papillomaviruses associated with Weddell seals and contributes to our understanding of the evolutionary history of papillomaviruses.

  1. QTLminer: identifying genes regulating quantitative traits

    Directory of Open Access Journals (Sweden)

    Schughart Klaus

    2010-10-01

    Full Text Available Abstract Background Quantitative trait locus (QTL mapping identifies genomic regions that likely contain genes regulating a quantitative trait. However, QTL regions may encompass tens to hundreds of genes. To find the most promising candidate genes that regulate the trait, the biologist typically collects information from multiple resources about the genes in the QTL interval. This process is very laborious and time consuming. Results QTLminer is a bioinformatics tool that automatically performs QTL region analysis. It is available in GeneNetwork and it integrates information such as gene annotation, gene expression and sequence polymorphisms for all the genes within a given genomic interval. Conclusions QTLminer substantially speeds up discovery of the most promising candidate genes within a QTL region.

  2. Identifying links between origami and compliant mechanisms

    Directory of Open Access Journals (Sweden)

    H. C. Greenberg

    2011-12-01

    Full Text Available Origami is the art of folding paper. In the context of engineering, orimimetics is the application of folding to solve problems. Kinetic origami behavior can be modeled with the pseudo-rigid-body model since the origami are compliant mechanisms. These compliant mechanisms, when having a flat initial state and motion emerging out of the fabrication plane, are classified as lamina emergent mechanisms (LEMs. To demonstrate the feasibility of identifying links between origami and compliant mechanism analysis and design methods, four flat folding paper mechanisms are presented with their corresponding kinematic and graph models. Principles from graph theory are used to abstract the mechanisms to show them as coupled, or inter-connected, mechanisms. It is anticipated that this work lays a foundation for exploring methods for LEM synthesis based on the analogy between flat-folding origami models and linkage assembly.

  3. DNA Barcoding Identifies Illegal Parrot Trade.

    Science.gov (United States)

    Gonçalves, Priscila F M; Oliveira-Marques, Adriana R; Matsumoto, Tania E; Miyaki, Cristina Y

    2015-01-01

    Illegal trade threatens the survival of many wild species, and molecular forensics can shed light on various questions raised during the investigation of cases of illegal trade. Among these questions is the identity of the species involved. Here we report a case of a man who was caught in a Brazilian airport trying to travel with 58 avian eggs. He claimed they were quail eggs, but authorities suspected they were from parrots. The embryos never hatched and it was not possible to identify them based on morphology. As 29% of parrot species are endangered, the identity of the species involved was important to establish a stronger criminal case. Thus, we identified the embryos' species based on the analyses of mitochondrial DNA sequences (cytochrome c oxidase subunit I gene [COI] and 16S ribosomal DNA). Embryonic COI sequences were compared with those deposited in BOLD (The Barcode of Life Data System) while their 16S sequences were compared with GenBank sequences. Clustering analysis based on neighbor-joining was also performed using parrot COI and 16S sequences deposited in BOLD and GenBank. The results, based on both genes, indicated that 57 embryos were parrots (Alipiopsitta xanthops, Ara ararauna, and the [Amazona aestiva/A. ochrocephala] complex), and 1 was an owl. This kind of data can help criminal investigations and to design species-specific anti-poaching strategies, and demonstrate how DNA sequence analysis in the identification of bird species is a powerful conservation tool. © The American Genetic Association 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  4. Identifying crucial parameter correlations maintaining bursting activity.

    Directory of Open Access Journals (Sweden)

    Anca Doloc-Mihu

    2014-06-01

    Full Text Available Recent experimental and computational studies suggest that linearly correlated sets of parameters (intrinsic and synaptic properties of neurons allow central pattern-generating networks to produce and maintain their rhythmic activity regardless of changing internal and external conditions. To determine the role of correlated conductances in the robust maintenance of functional bursting activity, we used our existing database of half-center oscillator (HCO model instances of the leech heartbeat CPG. From the database, we identified functional activity groups of burster (isolated neuron and half-center oscillator model instances and realistic subgroups of each that showed burst characteristics (principally period and spike frequency similar to the animal. To find linear correlations among the conductance parameters maintaining functional leech bursting activity, we applied Principal Component Analysis (PCA to each of these four groups. PCA identified a set of three maximal conductances (leak current, [Formula: see text]Leak; a persistent K current, [Formula: see text]K2; and of a persistent Na+ current, [Formula: see text]P that correlate linearly for the two groups of burster instances but not for the HCO groups. Visualizations of HCO instances in a reduced space suggested that there might be non-linear relationships between these parameters for these instances. Experimental studies have shown that period is a key attribute influenced by modulatory inputs and temperature variations in heart interneurons. Thus, we explored the sensitivity of period to changes in maximal conductances of [Formula: see text]Leak, [Formula: see text]K2, and [Formula: see text]P, and we found that for our realistic bursters the effect of these parameters on period could not be assessed because when varied individually bursting activity was not maintained.

  5. Melanoma biomolecules: independently identified but functionally intertwined

    Directory of Open Access Journals (Sweden)

    Danielle Erin Dye

    2013-09-01

    Full Text Available The majority of patients diagnosed with melanoma present with thin lesions and generally these patients have a good prognosis. However, 5% of patients with early melanoma (< 1mm thick will have recurrence and die within 10 years, despite no evidence of local or metastatic spread at the time of diagnosis. Thus, there is a need for additional prognostic markers to help identify those patients that may be at risk of recurrent disease. Many studies and several meta-analyses have compared gene and protein expression in melanocytes, naevi, primary and metastatic melanoma in an attempt to find informative prognostic markers for these patients. However, although a large number of putative biomarkers have been described, few of these molecules are informative when used in isolation. The best approach is likely to involve a combination of molecules. We believe one approach could be to analyze the expression of a group of interacting proteins that regulate different aspects of the metastatic pathway. This is because a primary lesion expressing proteins involved in multiple stages of metastasis may be more likely to lead to secondary disease than one that does not. This review focuses on five putative biomarkers - melanoma cell adhesion molecule (MCAM, galectin-3 (gal-3, matrix metalloproteinase 2 (MMP-2, chondroitin sulfate proteoglycan 4 (CSPG4 and paired box 3 (PAX3. The goal is to provide context around what is known about the contribution of these biomarkers to melanoma biology and metastasis. Although each of these molecules have been independently identified as likely biomarkers, it is clear from our analyses that each are closely linked with each other, with intertwined roles in melanoma biology.

  6. Identifying osteoporotic vertebral endplate and cortex fractures.

    Science.gov (United States)

    Wáng, Yì Xiáng J; Santiago, Fernando Ruiz; Deng, Min; Nogueira-Barbosa, Marcello H

    2017-10-01

    Osteoporosis is the most common metabolic bone disease, and vertebral fractures (VFs) are the most common osteoporotic fracture. A single atraumatic VF may lead to the diagnosis of osteoporosis. Prevalent VFs increase the risk of future vertebral and non-vertebral osteoporotic fracture independent of bone mineral density (BMD). The accurate and clear reporting of VF is essential to ensure patients with osteoporosis receive appropriate treatment. Radiologist has a vital role in the diagnosis of this disease. Several morphometrical and radiological methods for detecting osteoporotic VF have been proposed, but there is no consensus regarding the definition of osteoporotic VF. A vertebra may fracture yet not ever result in measurable changes in radiographic height or area. To overcome these difficulties, algorithm-based qualitative approach (ABQ) was developed with a focus on the identification of change in the vertebral endplate. Evidence of endplate fracture (rather than variation in vertebral shape) is the primary indicator of osteoporotic fracture according to ABQ criteria. Other changes that may mimic osteoporotic fractures should be systemically excluded. It is also possible that vertebral cortex fracture may not initially occur in endplate. Particularly, vertebral cortex fracture can occur in anterior vertebral cortex without gross vertebral deformity (VD), or fractures deform the anterior vertebral cortex without endplate disruption. This article aims to serve as a teaching material for physicians or researchers to identify vertebral endplate/cortex fracture (ECF). Emphasis is particularly dedicated to identifying ECF which may not be associated apparent vertebral body collapse. We believe a combined approach based on standardized radiologic evaluation by experts and morphometry measurement is the most appropriate approach to detect and classify VFs.

  7. Identifying osteoporotic vertebral endplate and cortex fractures

    Science.gov (United States)

    Santiago, Fernando Ruiz; Deng, Min; Nogueira-Barbosa, Marcello H.

    2017-01-01

    Osteoporosis is the most common metabolic bone disease, and vertebral fractures (VFs) are the most common osteoporotic fracture. A single atraumatic VF may lead to the diagnosis of osteoporosis. Prevalent VFs increase the risk of future vertebral and non-vertebral osteoporotic fracture independent of bone mineral density (BMD). The accurate and clear reporting of VF is essential to ensure patients with osteoporosis receive appropriate treatment. Radiologist has a vital role in the diagnosis of this disease. Several morphometrical and radiological methods for detecting osteoporotic VF have been proposed, but there is no consensus regarding the definition of osteoporotic VF. A vertebra may fracture yet not ever result in measurable changes in radiographic height or area. To overcome these difficulties, algorithm-based qualitative approach (ABQ) was developed with a focus on the identification of change in the vertebral endplate. Evidence of endplate fracture (rather than variation in vertebral shape) is the primary indicator of osteoporotic fracture according to ABQ criteria. Other changes that may mimic osteoporotic fractures should be systemically excluded. It is also possible that vertebral cortex fracture may not initially occur in endplate. Particularly, vertebral cortex fracture can occur in anterior vertebral cortex without gross vertebral deformity (VD), or fractures deform the anterior vertebral cortex without endplate disruption. This article aims to serve as a teaching material for physicians or researchers to identify vertebral endplate/cortex fracture (ECF). Emphasis is particularly dedicated to identifying ECF which may not be associated apparent vertebral body collapse. We believe a combined approach based on standardized radiologic evaluation by experts and morphometry measurement is the most appropriate approach to detect and classify VFs. PMID:29184768

  8. Use of lice to identify cowbird hosts

    Science.gov (United States)

    Hahn, D.C.; Price, R.D.; Osenton, P.C.

    2000-01-01

    The host specificity of avian lice (Phthiraptera) may be utilized by biologists to investigate the brood parasitism patterns of Brown-headed Cowbirds (Molothrus ater). As nestlings, brood parasites have a unique opportunity to encounter lice that are typically host specific. Lice are permanent hemimetabolic ectoparasites, a group found strictly on the body of the host, and they are transferred almost exclusively by bodily contact between hosts during care of young and at copulation. We investigated whether cowbird nestlings become infested with avian lice from their host parents and carry these lice away when they fledge, in effect bearing ectoparasite indicators of the species that raised them. The technique of examining the lice on cowbird fledglings to identify their foster parents would be much less costly than hiring a team of experts to determine parasitism patterns in the conventional way by finding hundreds of songbird nests. We examined 244 cowbird fledglings and found that they carried a rich fauna of lice representing 11 species and six genera, almost the entire spectrum of louse genera known to occur on passerines. We also examined 320 songbirds from 30 species, all known hosts of the Brown-headed Cowbird. As a group the host birds bore a diversity of louse species comparable to that on the fledgling cowbirds: 13 species of lice from seven genera. In contrast, most individual passerine host species yielded only 1 or 2 louse species, significantly fewer than the cowbird fledglings (p parasitism patterns. The incomplete state of passerine louse taxonomy requires anyone using this technique to de-louse both cowbird fledglings and local host species in order to have a reference collection of lice. Lice from cowbird fledglings can be identified by a skilled taxonomist and linked to particular host species, and the principal difficulty is the scarcity of skilled avian louse taxonomists. We also found an unusually rich louse fauna on 219 adult cowbirds, which

  9. Identifying functional decline: a methodological challenge

    Directory of Open Access Journals (Sweden)

    Grimmer K

    2013-08-01

    Full Text Available Karen Grimmer, Kate Beaton, Kevan Hendry International Centre for Allied Health Evidence, University of South Australia, Adelaide, SA, Australia Background: Functional decline (FD in older people has commonly been measured in the hospital setting with instruments which have been validated on decrease over time in capacity to undertake basic activities of daily living (ADL. In a nonhospitalized sample of older people (independently community dwelling, but potentially on the cusp of FD, it is possible that other measures could be used to predict decline. Early, accurate, and efficient identification of older community-dwelling people who are on the cusp of FD can assist in identifying appropriate interventions to slow the rate of decline. Methods: This paper reports on associations between four outcome measures which have been associated with FD (instrumental ADLs [IADLs], quality of life, hospitalizations and falls. The sample was older individuals who were discharged from one large metropolitan emergency department (ED during 2011–2012, without an inpatient admission. Results: Of 597 individuals aged 65+ who provided baseline information, 148 subjects provided four outcome measures at both 1 and 3 months follow up. Overall, approximately 24% demonstrated decreased IADL scores over the 3 months, with domains of home activities, laundry, shopping, and getting places declining the most. Over this time, 18% fell often, and 11% were consistently hospitalized. Between 1 and 3 months follow up, 41% declined in mental component scores, and 50% declined in physical component scores. Low mental and physical component quality of life scores were associated with downstream increased falls and hospitalizations, and decreased quality of life and IADLs. However, change in the four outcome measures was largely independent in factor analysis. Conclusion: Measuring the four outcome measures over 3 months post-discharge from an ED presentation, showed that

  10. Pseudonymization of patient identifiers for translational research.

    Science.gov (United States)

    Aamot, Harald; Kohl, Christian Dominik; Richter, Daniela; Knaup-Gregori, Petra

    2013-07-24

    The usage of patient data for research poses risks concerning the patients' privacy and informational self-determination. Next-generation-sequencing technologies and various other methods gain data from biospecimen, both for translational research and personalized medicine. If these biospecimen are anonymized, individual research results from genomic research, which should be offered to patients in a clinically relevant timeframe, cannot be associated back to the individual. This raises an ethical concern and challenges the legitimacy of anonymized patient samples. In this paper we present a new approach which supports both data privacy and the possibility to give feedback to patients about their individual research results. We examined previously published privacy concepts regarding a streamlined de-pseudonymization process and a patient-based pseudonym as applicable to research with genomic data and warehousing approaches. All concepts identified in the literature review were compared to each other and analyzed for their applicability to translational research projects. We evaluated how these concepts cope with challenges implicated by personalized medicine. Therefore, both person-centricity issues and a separation of pseudonymization and de-pseudonymization stood out as a central theme in our examination. This motivated us to enhance an existing pseudonymization method regarding a separation of duties. The existing concepts rely on external trusted third parties, making de-pseudonymization a multistage process involving additional interpersonal communication, which might cause critical delays in patient care. Therefore we propose an enhanced method with an asymmetric encryption scheme separating the duties of pseudonymization and de-pseudonymization. The pseudonymization service provider is unable to conclude the patient identifier from the pseudonym, but assigns this ability to an authorized third party (ombudsman) instead. To solve person-centricity issues, a

  11. Can we identify source lithology of basalt?

    Science.gov (United States)

    Yang, Zong-Feng; Zhou, Jun-Hong

    2013-01-01

    The nature of source rocks of basaltic magmas plays a fundamental role in understanding the composition, structure and evolution of the solid earth. However, identification of source lithology of basalts remains uncertainty. Using a parameterization of multi-decadal melting experiments on a variety of peridotite and pyroxenite, we show here that a parameter called FC3MS value (FeO/CaO-3*MgO/SiO2, all in wt%) can identify most pyroxenite-derived basalts. The continental oceanic island basalt-like volcanic rocks (MgO>7.5%) (C-OIB) in eastern China and Mongolia are too high in the FC3MS value to be derived from peridotite source. The majority of the C-OIB in phase diagrams are equilibrium with garnet and clinopyroxene, indicating that garnet pyroxenite is the dominant source lithology. Our results demonstrate that many reputed evolved low magnesian C-OIBs in fact represent primary pyroxenite melts, suggesting that many previous geological and petrological interpretations of basalts based on the single peridotite model need to be reconsidered.

  12. Process to identify and evaluate restoration options

    International Nuclear Information System (INIS)

    Strand, J.; Senner, S.; Weiner, A.; Rabinowitch, S.; Brodersen, M.; Rice, K.; Klinge, K.; MacMullin, S.; Yender, R.; Thompson, R.

    1993-01-01

    The restoration planning process has yielded a number of possible alternatives for restoring resources and services injured by the Exxon Valdez oil spill. They were developed by resource managers, scientists, and the public, taking into consideration the results of damage assessment and restoration studies and information from the scientific literature. The alternatives thus far identified include no action natural recovery, management of human uses, manipulation of resources, habitat protection and acquisition, acquisition of equivalent resources, and combinations of the above. Each alternative consists of a different mix of resource- or service-specific restoration options. To decide whether it was appropriate to spend restoration funds on a particular resource or service, first criteria had to be developed that evaluated available evidence for consequential injury and the adequacy and rate of natural recovery. Then, recognizing the range of effective restoration options, a second set of criteria was applied to determine which restoration options were the most beneficial. These criteria included technical feasibility, potential to improve the rate or degree of recovery, the relationship of expected costs to benefits, cost effectiveness, and the potential to restore the ecosystem as a whole. The restoration options considered to be most beneficial will be grouped together in several or more of the above alternatives and presented in a draft restoration plan. They will be further evaluated in a companion draft environmental impact statement

  13. Identifying Memory Allocation Patterns in HEP Software

    Science.gov (United States)

    Kama, S.; Rauschmayr, N.

    2017-10-01

    HEP applications perform an excessive amount of allocations/deallocations within short time intervals which results in memory churn, poor locality and performance degradation. These issues are already known for a decade, but due to the complexity of software frameworks and billions of allocations for a single job, up until recently no efficient mechanism has been available to correlate these issues with source code lines. However, with the advent of the Big Data era, many tools and platforms are now available to do large scale memory profiling. This paper presents, a prototype program developed to track and identify each single (de-)allocation. The CERN IT Hadoop cluster is used to compute memory key metrics, like locality, variation, lifetime and density of allocations. The prototype further provides a web based visualization back-end that allows the user to explore the results generated on the Hadoop cluster. Plotting these metrics for every single allocation over time gives a new insight into application’s memory handling. For instance, it shows which algorithms cause which kind of memory allocation patterns, which function flow causes how many short-lived objects, what are the most commonly allocated sizes etc. The paper will give an insight into the prototype and will show profiling examples for the LHC reconstruction, digitization and simulation jobs.

  14. NASA EOSDIS Data Identifiers: Approach and System

    Directory of Open Access Journals (Sweden)

    Lalit Wanchoo

    2017-04-01

    Full Text Available NASA’s Earth Science Data and Information System (ESDIS Project began investigating the use of Digital Object Identifiers (DOIs in 2010 with the goal of assigning DOIs to various data products. These Earth science research data products produced using Earth observations and models are archived and distributed by twelve Distributed Active Archive Centers (DAACs located across the United States. Each data center serves a different Earth science discipline user community and, accordingly, has a unique approach and process for generating and archiving a variety of data products. These varied approaches present a challenge for developing a DOI solution. To address this challenge, the ESDIS Project has developed processes, guidelines, and several models for creating and assigning DOIs. Initially the DOI assignment and registration process was started as a prototype but now it is fully operational. In February 2012, the ESDIS Project started using the California Digital Library (CDL EZID for registering DOIs. The DOI assignments were initially labor-intensive. The system is now automated, and the assignments are progressing rapidly. As of February 28, 2017, over 50% of the data products at the DAACs had been assigned DOIs. Citations using the DOIs increased from about 100 to over 370 between 2015 and 2016.

  15. Identifying Coevolving Partners from Paralogous Gene Families

    Directory of Open Access Journals (Sweden)

    Chen-Hsiang Yeang

    2008-01-01

    Full Text Available Many methods have been developed to detect coevolution from aligned sequences. However, all the existing methods require a one-to-one mapping of candidate coevolving partners (nucleotides, amino acids a priori. When two families of sequences have distinct duplication and loss histories, finding the one-to-one mapping of coevolving partners can be computationally involved. We propose an algorithm to identify the coevolving partners from two families of sequences with distinct phylogenetic trees. The algorithm maps each gene tree to a reference species tree, and builds a joint state of sequence composition and assignments of coevolving partners for each species tree node. By applying dynamic programming on the joint states, the optimal assignments can be identified. Time complexity is quadratic to the size of the species tree, and space complexity is exponential to the maximum number of gene tree nodes mapped to the same species tree node. Analysis on both simulated data and Pfam protein domain sequences demonstrates that the paralog coevolution algorithm picks up the coevolving partners with 60%–88% accuracy. This algorithm extends phylogeny-based coevolutionary models and make them applicable to a wide range of problems such as predicting protein-protein, protein-DNA and DNA-RNA interactions of two distinct families of sequences.

  16. Ebola Virus Infection Modelling and Identifiability Problems

    Directory of Open Access Journals (Sweden)

    Van-Kinh eNguyen

    2015-04-01

    Full Text Available The recent outbreaks of Ebola virus (EBOV infections have underlined the impact of the virus as a major threat for human health. Due to the high biosafety classification of EBOV (level 4, basic research is very limited. Therefore, the development of new avenues of thinking to advance quantitative comprehension of the virus and its interaction with the host cells is urgently neededto tackle this lethal disease. Mathematical modelling of the EBOV dynamics can be instrumental to interpret Ebola infection kinetics on quantitative grounds. To the best of our knowledge, a mathematical modelling approach to unravel the interaction between EBOV and the host cells isstill missing. In this paper, a mathematical model based on differential equations is used to represent the basic interactions between EBOV and wild-type Vero cells in vitro. Parameter sets that represent infectivity of pathogens are estimated for EBOV infection and compared with influenza virus infection kinetics. The average infecting time of wild-type Vero cells in EBOV is slower than in influenza infection. Simulation results suggest that the slow infecting time of EBOV could be compensated by its efficient replication. This study reveals several identifiability problems and what kind of experiments are necessary to advance the quantification of EBOV infection. A first mathematical approach of EBOV dynamics and the estimation of standard parametersin viral infections kinetics is the key contribution of this work, paving the way for future modelling work on EBOV infection.

  17. Identifying New Small Proteins in Escherichia coli.

    Science.gov (United States)

    VanOrsdel, Caitlin E; Kelly, John P; Burke, Brittany N; Lein, Christina D; Oufiero, Christopher E; Sanchez, Joseph F; Wimmers, Larry E; Hearn, David J; Abuikhdair, Fatimeh J; Barnhart, Kathryn R; Duley, Michelle L; Ernst, Sarah E G; Kenerson, Briana A; Serafin, Aubrey J; Hemm, Matthew R

    2018-04-12

    The number of small proteins (SPs) encoded in the Escherichia coli genome is unknown, as current bioinformatics and biochemical techniques make short gene and small protein identification challenging. One method of small protein identification involves adding an epitope tag to the 3' end of a short open reading frame (sORF) on the chromosome, with synthesis confirmed by immunoblot assays. In this study, this strategy was used to identify new E. coli small proteins, tagging 80 sORFs in the E. coli genome, and assayed for protein synthesis. The selected sORFs represent diverse sequence characteristics, including degrees of sORF conservation, predicted transmembrane domains, sORF direction with respect to flanking genes, ribosome binding site (RBS) prediction, and ribosome profiling results. Of 80 sORFs, 36 resulted in encoded synthesized proteins-a 45% success rate. Modeling of detected versus non-detected small proteins analysis showed predictions based on RBS prediction, transcription data, and ribosome profiling had statistically-significant correlation with protein synthesis; however, there was no correlation between current sORF annotation and protein synthesis. These results suggest substantial numbers of small proteins remain undiscovered in E. coli, and existing bioinformatics techniques must continue to improve to facilitate identification. © 2018 The Authors. Proteomics Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim, Towson University.

  18. Identifying pathways affected by cancer mutations.

    Science.gov (United States)

    Iengar, Prathima

    2017-12-16

    Mutations in 15 cancers, sourced from the COSMIC Whole Genomes database, and 297 human pathways, arranged into pathway groups based on the processes they orchestrate, and sourced from the KEGG pathway database, have together been used to identify pathways affected by cancer mutations. Genes studied in ≥15, and mutated in ≥10 samples of a cancer have been considered recurrently mutated, and pathways with recurrently mutated genes have been considered affected in the cancer. Novel doughnut plots have been presented which enable visualization of the extent to which pathways and genes, in each pathway group, are targeted, in each cancer. The 'organismal systems' pathway group (including organism-level pathways; e.g., nervous system) is the most targeted, more than even the well-recognized signal transduction, cell-cycle and apoptosis, and DNA repair pathway groups. The important, yet poorly-recognized, role played by the group merits attention. Pathways affected in ≥7 cancers yielded insights into processes affected. Copyright © 2017 Elsevier Inc. All rights reserved.

  19. Identifying a new particle with jet substructures

    International Nuclear Information System (INIS)

    Han, Chengcheng; Kim, Doojin; Kim, Minho; Postech, Pohang

    2017-01-01

    Here, we investigate a potential of determining properties of a new heavy resonance of mass O(1)TeV which decays to collimated jets via heavy Standard Model intermediary states, exploiting jet substructure techniques. Employing the Z gauge boson as a concrete example for the intermediary state, we utilize a "merged jet" defined by a large jet size to capture the two quarks from its decay. The use of the merged jet bene ts the identification of a Z-induced jet as a single, reconstructed object without any combinatorial ambiguity. We also find that jet substructure procedures may enhance features in some kinematic observables formed with subjet four-momenta extracted from a merged jet. This observation motivates us to feed subjet momenta into the matrix elements associated with plausible hypotheses on the nature of the heavy resonance, which are further processed to construct a matrix element method (MEM)-based observable. For both moderately and highly boosted Z bosons, we demonstrate that the MEM in combination with jet substructure techniques can be a very powerful tool for identifying its physical properties. Finally, we discuss effects from choosing different jet sizes for merged jets and jet-grooming parameters upon the MEM analyses.

  20. Identifying lubricant options for compressor bearing designs

    Science.gov (United States)

    Karnaz, J.; Seeton, C.; Dixon, L.

    2017-08-01

    Today’s refrigeration and air conditioning market is not only driven by the environmental aspects of the refrigerants, but also by the energy efficiency and reliability of system operation. Numerous types of compressor designs are used in refrigeration and air conditioning applications which means that different bearings are used; and in some cases, multiple bearing types within a single compressor. Since only one lubricant is used, it is important to try to optimize the lubricant to meet the various demands and requirements for operation. This optimization entails investigating different types of lubricant chemistries, viscosities, and various formulation options. What makes evaluating these options more challenging is the refrigerant which changes the properties of the lubricant delivered to the bearing. Once the lubricant and refrigerant interaction are understood, through various test methods, then work can start on collaborating with compressor engineers on identifying the lubricant chemistry and formulation options. These interaction properties are important to the design engineer to make decisions on the adequacy of the lubricant before compressor tests are started. This paper will discuss the process to evaluate lubricants for various types of compressors and bearing design with focus on what’s needed for current refrigerant trends. In addition, the paper will show how the lubricant chemistry choice can be manipulated through understanding of the bearing design and knowledge of interaction with the refrigerant to maximize performance. Emphasis will be placed on evaluation of synthetic lubricants for both natural and synthetic low GWP refrigerants.