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Sample records for weakly coordinating solvents

  1. An Aliphatic Solvent-Soluble Lithium Salt of the Perhalogenated Weakly Coordinating Anion [Al(OC(CCl3)(CF3)2)4](-).

    PubMed

    Zheng, Xin; Zhang, Zaichao; Tan, Gengwen; Wang, Xinping

    2016-02-01

    The facile synthesis of a new highly aliphatic solvent-soluble Li(+) salt of the perhalogenated weakly coordinating anion [Al(OC(CCl3)(CF3)2)4](-) and its application in stabilizing the Ph3C(+) cation were investigated. The lithium salt Li[Al(OC(CCl3)(CF3)2)4] (4) was prepared by the treatment of 4 mol equiv of HOC(CCl3)(CF3)2 with purified LiAlH4 in n-hexane from -20 °C to room temperature. Compound 4 is highly soluble in both polar and nonpolar solvents, and it bears both CCl3 and CF3 groups, resulting in a lower symmetry around the Al center compared to that of Li[Al(OC(CF3)3)4] (1). Treatment of 4 with Ph3CCl afforded the ionic compound [Ph3C][Al(OC(CCl3)(CF3)2)4] (5) bearing the Ph3C(+) cation with concomitant elimination of LiCl, suggesting the potential application of [Al(OC(CCl3)(CF3)2)4](-) in stabilizing reactive cationic species. Compounds 4 and 5 were fully characterized by spectroscopic and structural methods. PMID:26784742

  2. Influence of solute-solvent coordination on the orientational relaxation of ion assemblies in polar solvents

    NASA Astrophysics Data System (ADS)

    Ji, Minbiao; Hartsock, Robert W.; Sung, Zheng; Gaffney, Kelly J.

    2012-01-01

    We have investigated the rotational dynamics of lithium thiocyanate (LiNCS) dissolved in various polar solvents with time and polarization resolved vibrational spectroscopy. LiNCS forms multiple distinct ionic structures in solution that can be distinguished with the CN stretch vibrational frequency of the different ionic assemblies. By varying the solvent and the LiNCS concentration, the number and type of ionic structures present in solution can be controlled. Control of the ionic structure provides control over the volume, shape, and dipole moment of the solute, critical parameters for hydrodynamic and dielectric continuum models of friction. The use of solutes with sizes comparable to or smaller than the solvent molecules also helps amplify the sensitivity of the measurement to the short-ranged solute-solvent interaction. The measured orientational relaxation dynamics show many clear and distinct deviations from simple hydrodynamic behavior. All ionic structures in all solvents exhibit multi-exponential relaxation dynamics that do not scale with the solute volume. For Lewis base solvents such as benzonitrile, dimethyl carbonate, and ethyl acetate, the observed dynamics strongly show the effect of solute-solvent complex formation. For the weak Lewis base solvent nitromethane, we see no evidence for solute-solvent complex formation, but still see strong deviation from the predictions of simple hydrodynamic theory.

  3. Solvent extraction: the coordination chemistry behind extractive metallurgy.

    PubMed

    Wilson, A Matthew; Bailey, Phillip J; Tasker, Peter A; Turkington, Jennifer R; Grant, Richard A; Love, Jason B

    2014-01-01

    The modes of action of the commercial solvent extractants used in extractive hydrometallurgy are classified according to whether the recovery process involves the transport of metal cations, M(n+), metalate anions, MXx(n-), or metal salts, MXx into a water-immiscible solvent. Well-established principles of coordination chemistry provide an explanation for the remarkable strengths and selectivities shown by most of these extractants. Reagents which achieve high selectivity when transporting metal cations or metal salts into a water-immiscible solvent usually operate in the inner coordination sphere of the metal and provide donor atom types or dispositions which favour the formation of particularly stable neutral complexes that have high solubility in the hydrocarbons commonly used in recovery processes. In the extraction of metalates, the structures of the neutral assemblies formed in the water-immiscible phase are usually not well defined and the cationic reagents can be assumed to operate in the outer coordination spheres. The formation of secondary bonds in the outer sphere using, for example, electrostatic or H-bonding interactions are favoured by the low polarity of the water-immiscible solvents.

  4. Prediction of coordination number and relative solvent accessibility in proteins.

    PubMed

    Pollastri, Gianluca; Baldi, Pierre; Fariselli, Pietro; Casadio, Rita

    2002-05-01

    Knowing the coordination number and relative solvent accessibility of all the residues in a protein is crucial for deriving constraints useful in modeling protein folding and protein structure and in scoring remote homology searches. We develop ensembles of bidirectional recurrent neural network architectures to improve the state of the art in both contact and accessibility prediction, leveraging a large corpus of curated data together with evolutionary information. The ensembles are used to discriminate between two different states of residue contacts or relative solvent accessibility, higher or lower than a threshold determined by the average value of the residue distribution or the accessibility cutoff. For coordination numbers, the ensemble achieves performances ranging within 70.6-73.9% depending on the radius adopted to discriminate contacts (6A-12A). These performances represent gains of 16-20% over the baseline statistical predictor, always assigning an amino acid to the largest class, and are 4-7% better than any previous method. A combination of different radius predictors further improves performance. For accessibility thresholds in the relevant 15-30% range, the ensemble consistently achieves a performance above 77%, which is 10-16% above the baseline prediction and better than other existing predictors, by up to several percentage points. For both problems, we quantify the improvement due to evolutionary information in the form of PSI-BLAST-generated profiles over BLAST profiles. The prediction programs are implemented in the form of two web servers, CONpro and ACCpro, available at http://promoter.ics.uci.edu/BRNN-PRED/.

  5. Reactive p-block cations stabilized by weakly coordinating anions

    PubMed Central

    Engesser, Tobias A.; Lichtenthaler, Martin R.; Schleep, Mario

    2016-01-01

    The chemistry of the p-block elements is a huge playground for fundamental and applied work. With their bonding from electron deficient to hypercoordinate and formally hypervalent, the p-block elements represent an area to find terra incognita. Often, the formation of cations that contain p-block elements as central ingredient is desired, for example to make a compound more Lewis acidic for an application or simply to prove an idea. This review has collected the reactive p-block cations (rPBC) with a comprehensive focus on those that have been published since the year 2000, but including the milestones and key citations of earlier work. We include an overview on the weakly coordinating anions (WCAs) used to stabilize the rPBC and give an overview to WCA selection, ionization strategies for rPBC-formation and finally list the rPBC ordered in their respective group from 13 to 18. However, typical, often more organic ion classes that constitute for example ionic liquids (imidazolium, ammonium, etc.) were omitted, as were those that do not fulfill the – naturally subjective – “reactive”-criterion of the rPBC. As a rule, we only included rPBC with crystal structure and only rarely refer to important cations published without crystal structure. This collection is intended for those who are simply interested what has been done or what is possible, as well as those who seek advice on preparative issues, up to people having a certain application in mind, where the knowledge on the existence of a rPBC that might play a role as an intermediate or active center may be useful. PMID:26612538

  6. Weak Coordination as a Powerful Means for Developing Broadly Useful C–H Functionalization Reactions

    PubMed Central

    Engle, Keary M.; Mei, Tian-Sheng; Wasa, Masayuki

    2011-01-01

    functional group (or groups) can be used to chelate the metal catalyst and position it for selective C–H cleavage. Precoordination can overcome the paraffin nature of C–H bonds by increasing the effective concentration of the substrate so that it needn't be used as solvent. From a synthetic perspective, it is desirable to use a functional group that is an intrinsic part of the substrate so that extra steps for installation and removal of an external directing group can be avoided. In this way, dramatic increases in molecular complexity can be accomplished in a single stroke through stereo- and site-selective introduction of a new functional group. Although reactivity is a major challenge (as with first functionalization), the philosophy in further functionalization differs—the major challenge is developing reactions that work with predictable selectivity in intricately functionalized contexts on commonly occurring structural motifs. In this Account, we focus on an emergent theme within the further functionalization literature: the use of commonly occurring functional groups to direct C–H cleavage through weak coordinations. We discuss our motivation for studying Pd-catalyzed C–H functionalization assisted by weakly coordinating functional groups and chronicle our endeavors to bring reactions of this type to fruition. Through this approach, we have developed reactions with a diverse range of substrates and coupling partners, with the broad scope likely stemming from higher reactivity of the less stable cyclopalladated intermediates held in place by weak coordinations. PMID:22166158

  7. Rhenium complexes with weakly coordinating solvent ligands, cis[Re(PR{sub 3})(CO){sub 4}(L)][BAr{sub F}], L = CH{sub 2}Cl{sub 2}, Et{sub 2}O, NC{sub 5}F{sub 5}: Decomposition to chloride-bridged dimers in CH{sub 2}Cl{sub 2} solution

    SciTech Connect

    Huhmann-Vincent, J.; Scott, B.L.; Kubas, G.J.

    1999-01-11

    The solvent-coordinated complexes [cis-Re(CO){sub 4}(PR{sub 3})(S)][BAr{sub F}] (R = Ph, {sup i}Pr, Cy, BAr{sub F} = [B(3,5-(CF{sub 3}){sub 2}C{sub 6}H{sub 3}){sub 4}]{sup {minus}}) for S = Et{sub 2}O, CH{sub 2}Cl{sub 2}, and NC{sub 5}F{sub 5} have been prepared from reaction of the neutral methyl precursors, cis-Re-(CO){sub 4}(PR{sub 3})(Me), with either [H(OEt{sub 2}){sub 2}][BAr{sub F}] or [Ph{sub 3}C][BAr{sub F}] in the appropriate solvent. A crystal structure of the complex [cis-Re(CO){sub 4}(P{sup i}Pr{sub 3})(ClCH{sub 2}Cl)][BAr{sub F}] shows that the dichloromethane ligand is coordinated through one chlorine, with an Re-Cl distance of 2.554(2) {angstrom}. The first example of a structurally characterized pentafluoropyridine complex of rhenium was also determined, [cis-Re(CO){sub 4}(P{sup i}Pr{sub 3})(NC{sub 5}F{sub 5})][BAr{sub F}], with an Re-N distance of 2.319(5) {angstrom}. Activation of C-Cl bonds in the dichloromethane complexes result in the formation of the chloride-bridged dimers, {l_brace}[cis-Re(CO){sub 4}(PR{sub 3})]{sub 2}({mu}-Cl){r_brace}{l_brace}BAr{sub f}{r_brace}, and the X-ray structures of the Ph and Cy derivatives were determined.

  8. COORDINATION COMPOUND-SOLVENT EXTRACTION PROCESS FOR URANIUM RECOVERY

    DOEpatents

    Reas, W.H.

    1959-03-10

    A method is presented for the separation of uranium from aqueous solutions containing a uranyl salt and thorium. Thc separation is effected by adding to such solutions an organic complexing agent, and then contacting the solution with an organic solvent in which the organic complexing agent is soluble. By use of the proper complexing agent in the proper concentrations uranium will be complexed and subsequently removed in the organic solvent phase, while the thorium remains in the aqueous phase. Mentioned as suitable organic complexing agents are antipyrine, bromoantipyrine, and pyramidon.

  9. Photoinduced strong acid–weak base reactions in a polar aprotic solvent

    NASA Astrophysics Data System (ADS)

    Lee, Young Min; Park, Sun-Young; Kim, Heesu; Gyum Kim, Taeg; Kwon, Oh-Hoon

    2016-06-01

    The excited-state proton transfer (ESPT) of the strong photoacid, N-methyl-7-hydroxyquinolinium, was studied in the presence of different weak bases such as methanol, ethanol, and dimethyl sulfoxide in an aprotic solvent of acetonitrile. Here, we present chemical kinetics analysis of the ESPT mechanism to explain biphasic fluorescence decay of the parent photoacid and the sign reversal of the rise and decay of the resulting conjugate-base fluorescence. The ESPT of the free photoacid showed a molecularity of 2 with reacting alcohol molecules. In the ground state, it was found that a fraction of the photoacid formed 1 : 2 hydrogen-bonded complexes with the residual water present in the aprotic solvent or 1 : 1 complexes with the additive alcohols. In the excited state, these adducts underwent proton transfer when complexed further with diffusing alcohol molecules.

  10. Photoinduced strong acid-weak base reactions in a polar aprotic solvent

    NASA Astrophysics Data System (ADS)

    Lee, Young Min; Park, Sun-Young; Kim, Heesu; Gyum Kim, Taeg; Kwon, Oh-Hoon

    2016-06-01

    The excited-state proton transfer (ESPT) of the strong photoacid, N-methyl-7-hydroxyquinolinium, was studied in the presence of different weak bases such as methanol, ethanol, and dimethyl sulfoxide in an aprotic solvent of acetonitrile. Here, we present chemical kinetics analysis of the ESPT mechanism to explain biphasic fluorescence decay of the parent photoacid and the sign reversal of the rise and decay of the resulting conjugate-base fluorescence. The ESPT of the free photoacid showed a molecularity of 2 with reacting alcohol molecules. In the ground state, it was found that a fraction of the photoacid formed 1 : 2 hydrogen-bonded complexes with the residual water present in the aprotic solvent or 1 : 1 complexes with the additive alcohols. In the excited state, these adducts underwent proton transfer when complexed further with diffusing alcohol molecules.

  11. Coordinative Properties of Highly Fluorinated Solvents with Amino and Ether Groups

    PubMed Central

    Boswell, Paul G.; Lugert, Elizabeth C.; Rábai, József; Amin, Elizabeth A.; Bühlmann, Philippe

    2008-01-01

    In spite of the widespread use of perfluorinated solvents with amino and ether groups in a variety of application fields, the coordinative properties of these compounds are poorly known. It is generally assumed that the electron withdrawing perfluorinated moieties render these functional groups rather inert, but little is known quantitatively about the extent of their inertness. This paper reports on the interactions between inorganic monocations and perfluorotripentylamine and 2H-perfluoro-5,8,11-trimethyl-3,6,9,12-tetraoxapentadecane, as determined with fluorous liquid-membrane cation-selective electrodes doped with tetrakis[3,5-bis(perfluorohexyl)phenyl]borate salts. The amine does not undergo measurable association with any ion tested, and its formal pKa is shown to be smaller than -0.5. This is consistent with the nearly planar structure of the amine at its nitrogen center, as obtained with density functional theory calculations. The tetraether interacts very weakly with Na+ and Li+. Assuming 1:1 stoichiometry, formal association constants were determined to be 2.3 and 1.5 M-1, respectively. This disproves an earlier proposition that the Lewis base character in such compounds may be non-existent. Due to the extremely low polarity of fluorous solvents and the resulting high extent of ion pair formation, a fluorophilic electrolyte salt with perfluoroalkyl substituents on both the cation and the anion had to be developed for these experiments. In its pure form, this first fluorophilic electrolyte salt is an ionic liquid with a glass transition temperature, Tg, of -18.5 °C. Interestingly, the molar conductivity of solutions of this salt increases very steeply in the high concentration range, making it a particularly effective electrolyte salt. PMID:16316244

  12. Organometallic electrochemistry based on electrolytes containing weakly-coordinating fluoroarylborate anions.

    PubMed

    Geiger, William E; Barrière, Frédéric

    2010-07-20

    Electrochemistry is a powerful tool for the study of oxidative electron-transfer reactions (anodic processes). Since the 1960s, the electrolytes of choice for nonaqueous electrochemistry were relatively small (heptaatomic or smaller) inorganic anions, such as perchlorate, tetrafluoroborate, or hexafluorophosphate. Owing to the similar size-to-charge ratios of these "traditional" anions, structural alterations of the electrolyte anion are not particularly valuable in effecting changes in the corresponding redox reactions. Systematic variations of supporting electrolytes were largely restricted to cathodic processes, in which interactions of anions produced in the reactions are altered by changes in electrolyte cations. A typical ladder involves going from a weakly ion-pairing tetraalkylammonium cation, [N(C(n)H(2n+1))(4)](+), with n > or = 4, to more strongly ion-pairing counterparts with n < 4, and culminating in very strongly ion-pairing alkali metal ions. A new generation of supporting electrolyte salts that incorporate a weakly coordinating anion (WCA) expands anodic applications by providing a dramatically different medium in which to generate positively charged electrolysis products. A chain of electrolyte anions is now available for the control of anodic reactions, beginning with weakly ion-pairing WCAs, progressing through the traditional anions, and culminating in halide ions. Although the electrochemical properties of a number of different WCAs have been reported, the most systematic work involves fluoro- or trifluoromethyl-substituted tetraphenylborate anions (fluoroarylborate anions). In this Account, we focus on tetrakis(perfluorophenyl)borate, [B(C(6)F(5))(4)](-), which has a significantly more positive anodic window than tetrakis[(3,5-bis(trifluoromethyl)phenyl)]borate, [BArF(24)](-), making it suitable in a larger range of anodic oxidations. These WCAs also have a characteristic of specific importance to organometallic redox processes. Many electron

  13. A multi-functional coordination polymer coexisting spontaneous chirality resolution and weak ferromagnetism

    SciTech Connect

    Li, Xiu-Hua; Zhang, Qi; Hu, Ping

    2014-10-15

    A multifunctional homochiral coordination polymer, [Co(H{sub 2}O)(BDC)(4,4′-BPY)]∙3H{sub 2}O (1) (H{sub 2}BDC=1,2-benzenedicarboxylate and 4,4′-BPY=4,4′-bipyridine), has been successfully isolated from Co(II) ions and mixed ligands (1,2-benzenedicarboxylate and 4,4′-bipyridine). Complex 1, which exhibits spontaneous chirality resolution and weak ferromagnetism, is built by chiral helices interconnected via end-to-end 4,4′-BPY bridges into a two-dimensional (2D) layer structure. - Graphical abstract: A 2D cobalt coordination polymer compound showing spontaneous chirality resolution and weak ferromagnetism. - Highlights: • A new 2D cobalt mix-ligand coordination polymer complex has been synthesized. • The cobalt coordination polymer complex shows spontaneous chirality resolution in solid state. • The cobalt coordination polymer complex displays dominant and weak intrachain ferromagnetic interactions.

  14. Pd(II) coordinated deprotonated diphenyl phosphino amino pyridine: reactivity towards solvent, base, and acid.

    PubMed

    Pratihar, Sanjay; Pegu, Rupa; Guha, Ankur Kanti; Sarma, Bipul

    2014-12-01

    The reactivity and stability of P(III)-N and P(III)≈N bonds will be different towards various solvents, bases, and acids because of their difference in bond strength due to different N-pπ-P-dπ donor bonding. For this, a P≈N containing Pd(II) complex, [Pd(DPAP)2] (C1), was synthesized from the reaction between PdCl2(COD) (COD = 1,4-cyclooctadiene) and 2 equiv. DPAP (diphenyl phosphino amino pyridine) ligand, followed by deprotonation of the N-H proton of the coordinated DPAP. The reactivity and stability of coordinated P≈N in complex C1 were determined in various protic and aprotic solvents, bases, and acids. The inertness of coordinated P=N towards various solvents and bases was observed, whereas protonation occurs at the nitrogen of P=N in the presence of an acid to form P-NH, with the generation of dicationic palladium complexes (C2). The dicationic complex C2 is found to be stable in the presence of bulky monoanionic Sn(IV) reagents, whereas, in the presence of more nucleophilic anions like Br(-) or I(-), dissociation of one DPAP ligand from dicationic Pd(II) complexes C2 leads to the generation of Pd(DPAP)X2 (X = Br(-), I(-)). Finally, the utility of the complexes towards Suzuki coupling of various aryl bromides and aryl or heteraryl boronic acids has been checked.

  15. Retrieval-based Face Annotation by Weak Label Regularized Local Coordinate Coding.

    PubMed

    Wang, Dayong; Hoi, Steven C H; He, Ying; Zhu, Jianke; Mei, Tao; Luo, Jiebo

    2013-08-01

    Retrieval-based face annotation is a promising paradigm of mining massive web facial images for automated face annotation. This paper addresses a critical problem of such paradigm, i.e., how to effectively perform annotation by exploiting the similar facial images and their weak labels which are often noisy and incomplete. In particular, we propose an effective Weak Label Regularized Local Coordinate Coding (WLRLCC) technique, which exploits the principle of local coordinate coding in learning sparse features, and employs the idea of graph-based weak label regularization to enhance the weak labels of the similar facial images. We present an efficient optimization algorithm to solve the WLRLCC task. We conduct extensive empirical studies on two large-scale web facial image databases: (i) a Western celebrity database with a total of $6,025$ persons and $714,454$ web facial images, and (ii)an Asian celebrity database with $1,200$ persons and $126,070$ web facial images. The encouraging results validate the efficacy of the proposed WLRLCC algorithm. To further improve the efficiency and scalability, we also propose a PCA-based approximation scheme and an offline approximation scheme (AWLRLCC), which generally maintains comparable results but significantly saves much time cost. Finally, we show that WLRLCC can also tackle two existing face annotation tasks with promising performance.

  16. Unusual Transformation from a Solvent-Stabilized 1D Coordination Polymer to a Metal-Organic Framework (MOF)-Like Cross-Linked 3D Coordination Polymer.

    PubMed

    Lee, Seung-Chul; Choi, Eun-Young; Lee, Sang-Beom; Kim, Sang-Wook; Kwon, O-Pil

    2015-10-26

    An unusual 1D-to-3D transformation of a coordination polymer based on organic linkers containing highly polar push-pull π-conjugated side chains is reported. The coordination polymers are synthesized from zinc nitrate and an organic linker, namely, 2,5-bis{4-[1-(4-nitrophenyl)pyrrolidin-2-yl]butoxy}terephthalic acid, which possesses highly polar (4-nitrophenyl)pyrrolidine groups, with high dipole moments of about 7 D. The coordination polymers exhibit an unusual transformation from a soluble, solvent-stabilized 1D coordination polymer into an insoluble, metal-organic framework (MOF)-like 3D coordination polymer. The coordination polymer exhibits good film-forming ability, and the MOF-like films are insoluble in conventional organic solvents.

  17. Four unexpected lanthanide coordination polymers involving in situ reaction of solvent N, N-Dimethylformamide

    SciTech Connect

    Jin, Jun-Cheng; Tong, Wen-Quan; Fu, Ai-Yun; Xie, Cheng-Gen; Chang, Wen-Gui; Wu, Ju; Xu, Guang-Nian; Zhang, Ya-Nan; Li, Jun; Li, Yong; Yang, Peng-Qi

    2015-05-15

    Four unexpected 2D lanthanide coordination polymers have been synthesized through in situ reactions of DMF solvent under solvothermal conditions. The isostructural complexes 1–3 contain four types of 2{sub 1} helical chains. While the Nd(III) ions are bridged through μ{sub 2}-HIDC{sup 2−} and oxalate to form a 2D sheet along the bc plane without helical character in 4. Therefore, complex 1 exhibits bright red solid-state phosphorescence upon exposure to UV radiation at room temperature. - Graphical abstract: Four unexpected 2D lanthanide coordination polymers have been synthesized through in situ reactions of solvent DMF to formate acid or oxalic acid under solvothermal conditions. The isostructural complexes 1–3 contain four types of different 2{sub 1} helical chains in the 2D layer and 1 exhibits bright red solid-state phosphorescence upon UV radiation. - Highlights: • Four unexpected 2D lanthanide coordination compounds have been synthesized through in situ reactions under solvothermal conditions. • The complexes 1–3 contain four types of 2{sub 1} helical chains in the layer. • Complex 1 exhibits bright red solid-state phosphorescence upon exposure to UV radiation at room temperature.

  18. Assessment of solvent effects: do weak alignment media affect the structure of the solute?

    PubMed

    Shahkhatuni, Astghik A; Shahkhatuni, Aleksan G; Panosyan, Henry A; Sahakyan, Aleksandr B; Byeon, In-Ja L; Gronenborn, Angela M

    2007-07-01

    Alignment media used for measuring residual dipolar couplings, such as solutions of filamentous phages, phospholipid mixtures, polyacrylamide gels and various lyotropic liquid crystalline systems were investigated with respect to solvent effects on molecular structure. Structural parameters of the small rigid model compound 13C-acetonitrile were calculated from dipolar couplings and variations from expectation values were used for assessment of solvent effects. Only minor solvent effects were observed for most of the media employed and the measured structural data are in good agreement with microwave data and theoretical predictions. PMID:17534883

  19. Synthesis and Structural Characterization of Magnesium Based Coordination Networks in Different Solvents

    SciTech Connect

    Banerjee, Debasis; Finkelstein, Jeffrey; Smirnov, A.; Forster, Paul M.; Borkowski, Lauren A.; Teat, Simon J.; Parise, John B.

    2015-10-15

    Three magnesium based metal-organic frameworks, Mg{sub 3}(3,5-PDC){sub 3}(DMF){sub 3} {center_dot} DMF [1], Mg(3,5-PDC)(H{sub 2}O) {center_dot} (H{sub 2}O) [3], and Mg4(3,5-PDC)4(DMF){sub 2}(H{sub 2}O){sub 2} {center_dot} 2DMF {center_dot} 4.5H{sub 2}O [4], and a 2-D coordination polymer, [Mg(3,5-PDC)(H{sub 2}O){sub 2}] [2] [PDC = pyridinedicarboxylate], were synthesized using a combination of DMF, methanol, ethanol, and water. Compound 1 [space group P2{sub 1}/n, a = 12.3475(5) {angstrom}, b = 11.1929(5) {angstrom}, c = 28.6734(12) {angstrom}, {beta} = 98.8160(10){sup o}, V = 3916.0(3) {angstrom}{sup 3}] consists of a combination of isolated and corner-sharing magnesium octahedra connected by the organic linkers to form a 3-D network with a 12.2 {angstrom} x 4.6 {angstrom} 1-D channel. The channel contains coordinated and free DMF molecules. In compound 2 [space group C2/c, a = 9.964(5) {angstrom}, b = 12.0694(6) {angstrom}, c = 7.2763(4) {angstrom}, {beta} = 106.4970(6){sup o}, V = 836.70(6) {angstrom}{sup 3}], PDC connects isolated seven coordinated magnesium polyhedra into a layered structure. Compound 3 [space group P6{sub 1}22, a = 11.479(1) {angstrom}, c = 14.735(3) {angstrom}, V = 1681.7(4) {angstrom}{sup 3}] (previously reported) contains isolated magnesium octahedra connected by the organic linker with each other forming a 3D network. Compound 4 [space group P2{sub 1}/c, a = 13.7442(14) {angstrom}, b = 14.2887(15) {angstrom}, c = 14.1178(14) {angstrom}, {beta} = 104.912(2){sup o}, V = 2679.2(5) {angstrom}{sup 3}] also exhibits a 3D network based on isolated magnesium octahedra with square cavities containing both disordered DMF and water molecules. The structural topologies originate due to the variable coordination ability of solvent molecules with the metal center. Water molecules coordinate with the magnesium metal centers preferably over other polar solvents (DMF, methanol, ethanol) used to synthesize the coordination networks. Despite testing

  20. An europium(III) diglycolamide complex: insights into the coordination chemistry of lanthanides in solvent extraction.

    PubMed

    Antonio, Mark R; McAlister, Daniel R; Horwitz, E Philip

    2015-01-14

    The synthesis, stoichiometry, and structural characterization of a homoleptic, cationic europium(III) complex with three neutral tetraalkyldiglycolamide ligands are reported. The tri(bismuth tetrachloride)tris(N,N,N',N'-tetra-n-octyldiglycolamide)Eu salt, [Eu(TODGA)3][(BiCl4)3] obtained from methanol was examined by Eu L3-edge X-ray absorption spectroscopy (XAS) to reveal an inner-sphere coordination of Eu(3+) that arises from 9 O atoms and two next-nearest coordination spheres that arise from 6 carbon atoms each. A structural model is proposed in which each TODGA ligand with its O=Ca-Cb-O-Cb-Ca=O backbone acts as a tridentate O donor, where the two carbonyl O atoms and the one ether O atom bond to Eu(3+). Given the structural rigidity of the tridentate coordination motif in [Eu(TODGA)3](3+) with six 5-membered chelate rings, the six Eu-Ca and six Eu-Cb interactions are readily resolved in the EXAFS (extended X-ray absorption fine structure) spectrum. The three charge balancing [BiCl4](-) anions are beyond the cationic [Eu(TODGA)3](3+) cluster in an outer sphere environment that is too distant to be detected by XAS. Despite their sizeable length and propensity for entanglement, the four n-octyl groups of each TODGA (for a total of twelve) do not perturb the Eu(3+) coordination environment over that seen from previously reported single-crystal structures of tripositive lanthanide (Ln(3+)) complexes with tetraalkyldiglycolamide ligands (of the same 1:3 metal-to-ligand ratio stoichiometry) but having shorter i-propyl and i-butyl groups. The present results set the foundation for understanding advanced solvent extraction processes for the separation of the minor, tripositive actinides (Am, Cm) from the Ln(3+) ions in terms of the local structure of Eu(3+) in a solid state coordination complex with TODGA.

  1. Distinct dissociation kinetics between ion pairs: Solvent-coordinate free-energy landscape analysis.

    PubMed

    Yonetani, Yoshiteru

    2015-07-28

    Different ion pairs exhibit different dissociation kinetics; however, while the nature of this process is vital for understanding various molecular systems, the underlying mechanism remains unclear. In this study, to examine the origin of different kinetic rate constants for this process, molecular dynamics simulations were conducted for LiCl, NaCl, KCl, and CsCl in water. The results showed substantial differences in dissociation rate constant, following the trend kLiCl < kNaCl < kKCl < kCsCl. Analysis of the free-energy landscape with a solvent reaction coordinate and subsequent rate component analysis showed that the differences in these rate constants arose predominantly from the variation in solvent-state distribution between the ion pairs. The formation of a water-bridging configuration, in which the water molecule binds to an anion and a cation simultaneously, was identified as a key step in this process: water-bridge formation lowers the related dissociation free-energy barrier, thereby increasing the probability of ion-pair dissociation. Consequently, a higher probability of water-bridge formation leads to a higher ion-pair dissociation rate.

  2. Distinct dissociation kinetics between ion pairs: Solvent-coordinate free-energy landscape analysis

    NASA Astrophysics Data System (ADS)

    Yonetani, Yoshiteru

    2015-07-01

    Different ion pairs exhibit different dissociation kinetics; however, while the nature of this process is vital for understanding various molecular systems, the underlying mechanism remains unclear. In this study, to examine the origin of different kinetic rate constants for this process, molecular dynamics simulations were conducted for LiCl, NaCl, KCl, and CsCl in water. The results showed substantial differences in dissociation rate constant, following the trend kLiCl < kNaCl < kKCl < kCsCl. Analysis of the free-energy landscape with a solvent reaction coordinate and subsequent rate component analysis showed that the differences in these rate constants arose predominantly from the variation in solvent-state distribution between the ion pairs. The formation of a water-bridging configuration, in which the water molecule binds to an anion and a cation simultaneously, was identified as a key step in this process: water-bridge formation lowers the related dissociation free-energy barrier, thereby increasing the probability of ion-pair dissociation. Consequently, a higher probability of water-bridge formation leads to a higher ion-pair dissociation rate.

  3. Anti-kindling Induced by Two-Stage Coordinated Reset Stimulation with Weak Onset Intensity

    PubMed Central

    Zeitler, Magteld; Tass, Peter A.

    2016-01-01

    Abnormal neuronal synchrony plays an important role in a number of brain diseases. To specifically counteract abnormal neuronal synchrony by desynchronization, Coordinated Reset (CR) stimulation, a spatiotemporally patterned stimulation technique, was designed with computational means. In neuronal networks with spike timing–dependent plasticity CR stimulation causes a decrease of synaptic weights and finally anti-kindling, i.e., unlearning of abnormally strong synaptic connectivity and abnormal neuronal synchrony. Long-lasting desynchronizing aftereffects of CR stimulation have been verified in pre-clinical and clinical proof of concept studies. In general, for different neuromodulation approaches, both invasive and non-invasive, it is desirable to enable effective stimulation at reduced stimulation intensities, thereby avoiding side effects. For the first time, we here present a two-stage CR stimulation protocol, where two qualitatively different types of CR stimulation are delivered one after another, and the first stage comes at a particularly weak stimulation intensity. Numerical simulations show that a two-stage CR stimulation can induce the same degree of anti-kindling as a single-stage CR stimulation with intermediate stimulation intensity. This stimulation approach might be clinically beneficial in patients suffering from brain diseases characterized by abnormal neuronal synchrony where a first treatment stage should be performed at particularly weak stimulation intensities in order to avoid side effects. This might, e.g., be relevant in the context of acoustic CR stimulation in tinnitus patients with hyperacusis or in the case of electrical deep brain CR stimulation with sub-optimally positioned leads or side effects caused by stimulation of the target itself. We discuss how to apply our method in first in man and proof of concept studies. PMID:27242500

  4. Salts of highly fluorinated weakly coordinating anions as versatile precursors towards hydrogen storage materials.

    PubMed

    Starobrat, A; Tyszkiewicz, M J; Wegner, W; Pancerz, D; Orłowski, P A; Leszczyński, P J; Fijalkowski, K J; Jaroń, T; Grochala, W

    2015-12-01

    We report the most recent results related to application of a metathetic pathway towards mixed-metal borohydrides. The synthetic protocol utilizes highly-fluorinated weakly coordinating anion salts as precursors. We discuss the technicalities related to the use of fluorine-rich anions as well as the improvements which are still needed to deliver high-purity materials with potential applications for hydrogen storage. The applicability of the method is expanded beyond the previously described complex borohydrides of alkali metal Zn or Y, towards the systems containing Mg(II), Sc(III), Mn(II), or Eu(III). We have prepared for the first time [Ph4P]2[Mn(BH4)4] and [Me4N]2[Mg(BH4)4], solved their crystal structures from powder x-ray diffraction, and used selected organic metal borohydride derivatives as precursors towards mixed-metal borohydrides (K2Mn(BH4)4, Rb3Mg(BH4)5, etc.). We have also prepared [Ph4P][Eu(BH4)4], which is the first derivative of Eu(III) in the homoleptic environment of borohydride anions.

  5. Weak coordination among petiole, leaf, vein, and gas-exchange traits across 41 Australian angiosperm species and its possible implications

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Background and Aims Close coordination between leaf gas exchange and maximal hydraulic supply has been reported across diverse plant life-forms. However, recent reports suggest that this relationship may become weak or break down completely within the angiosperms. Methods To examine this possi...

  6. Selective and effective binding of pillar[5,6]arenes toward secondary ammonium salts with a weakly coordinating counteranion.

    PubMed

    Li, Chunju; Shu, Xiaoyan; Li, Jian; Fan, Jiazeng; Chen, Zhenxia; Weng, Linhong; Jia, Xueshun

    2012-08-17

    The selective and effective binding of secondary ammoniums with a weakly coordinating tetrakis[3,5-bis(trifluoromethyl)phenyl]borate (BArF) counteranion by per-ethylated pillar[5,6]arenes is reported. The construction of a first pillararene-based self-sorting system consisting of two wheels and two axles is also described. PMID:22866893

  7. Weakly coordinating anions: crystallographic and NQR studies of halogen-metal bonding in silver, thallium, sodium, and potassium halomethanesulfonates.

    PubMed

    Wulfsberg, Gary; Parks, Katherine D; Rutherford, Richard; Jackson, Debra Jones; Jones, Frank E; Derrick, Dana; Ilsley, William; Strauss, Steven H; Miller, Susie M; Anderson, Oren P; Babushkina, T A; Gushchin, S I; Kravchenko, E A; Morgunov, V G

    2002-04-22

    35Cl, (79,81)Br, and (127)I NQR (nuclear quadrupole resonance) spectroscopy in conjunction with X-ray crystallography is potentially one of the best ways of characterizing secondary bonding of metal cations such as Ag(+) to halogen donor atoms on the surfaces of very weakly coordinating anions. We have determined the X-ray crystal structure of Ag(O(3)SCH(2)Cl) (a = 13.241(3) A; b = 7.544(2) A; c = 4.925(2) A; orthorhombic; space group Pnma; Z = 4) and compared it with the known structure of Ag(O(3)SCH(2)Br) (Charbonnier, F.; Faure, R.; Loiseleur, H. Acta Crystallogr., Sect. B 1978, 34, 3598-3601). The halogen atom in each is apical (three-coordinate), being weakly coordinated to two silver ions. (127)I NQR studies on Ag(O(3)SCH(2)I) show the expected NQR consequences of three-coordination of iodine: substantially reduced NQR frequencies nu(1) and nu(2) and a fairly small NQR asymmetry parameter eta. The reduction of the halogen NQR frequency of the coordinating halogen atom in Ag(O(3)SCH(2)X) becomes more substantial in the series X = Cl < Br < I, indicating that the coordination to Ag(+) strengthens in this series, as expected from hard-soft acid-base principles. The numbers of electrons donated by the organic iodine atom to Ag(+) have been estimated; these indicate that the bonding to the cation is weak but not insignificant. We have not found any evidence for the bonding of these organohalogen atoms to another soft-acid metal ion, thallium. A scheme for recycling of thallium halide wastes is included.

  8. Palladium-Catalyzed Site-Selective C-H Functionalization of Weakly Coordinating Sulfonamides: Synthesis of Biaryl Sulfonamides.

    PubMed

    Vanjari, Rajeshwer; Guntreddi, Tirumaleswararao; Singh, Krishna Nand

    2016-03-01

    A novel and site selective C-H functionalization of unsubstituted sulfonamides has been developed for the synthesis of ortho aryl sulfonamides. The reaction involves highly regioselective ortho mono arylation of weakly coordinating SO2 NH2 directing group by means of aryl iodides. Palladium acetate in the presence of silver(I) oxide is found to be the most effective catalytic system. PMID:26763530

  9. Layer-by-layer modification of high surface curvature nanoparticles with weak polyelectrolytes using a multiphase solvent precipitation process.

    PubMed

    Nagaraja, Ashvin T; You, Yil-Hwan; Choi, Jeong-Wan; Hwang, Jin-Ha; Meissner, Kenith E; McShane, Michael J

    2016-03-15

    The layer-by-layer modification of ≈5 nm mercaptocarboxylic acid stabilized gold nanoparticles was studied in an effort to illustrate effective means to overcome practical issues in handling and performing surface modification of such extremely small materials. To accomplish this, each layer deposition cycle was separated into a multi-step process wherein solution pH was controlled in two distinct phases of polyelectrolyte adsorption and centrifugation. Additionally, a solvent precipitation step was introduced to make processing more amenable by concentrating the sample and exchanging solution pH before ultracentrifugation. The pH-dependent assembly on gold nanoparticles was assessed after each layer deposition cycle by monitoring the plasmon peak absorbance location, surface charge, and the percentage of nanoparticles recovered. The selection of solution pH during the adsorption phase was found to be a critical parameter to enhance particle recovery and maximize surface charge when coating with weak polyelectrolytes. One bilayer was deposited with a high yield and the modified particles exhibited enhanced colloidal stability across a broad pH range and increased ionic strength. These findings support the adoption of this multi-step processing approach as an effective and generalizable approach to improve stability of high surface curvature particles. PMID:26771506

  10. Solvent-vapour-assisted pathways and the role of pre-organization in solid-state transformations of coordination polymers

    PubMed Central

    Wright, James S.; Vitórica-Yrezábal, Iñigo J.; Adams, Harry; Thompson, Stephen P.; Hill, Adrian H.; Brammer, Lee

    2015-01-01

    A family of one-dimensional coordination polymers, [Ag4(O2C(CF2)2CF3)4(phenazine)2(arene)n]·m(arene), 1 (arene = toluene or xylene), have been synthesized and crystallographically characterized. Arene guest loss invokes structural transformations to yield a pair of polymorphic coordination polymers [Ag4(O2C(CF2)2CF3)4(phenazine)2], 2a and/or 2b, with one- and two-dimensional architectures, respectively. The role of pre-organization of the polymer chains of 1 in the selectivity for formation of either polymorph is explored, and the templating effect of toluene and p-xylene over o-xylene or m-xylene in the formation of arene-containing architecture 1 is also demonstrated. The formation of arene-free phase 2b, not accessible in a phase-pure form through other means, is shown to be the sole product of loss of toluene from 1-tol·tol [Ag4(O2C(CF2)2CF3)4(phenazine)2(toluene)]·2(toluene), a phase containing toluene coordinated to Ag(I) in an unusual μ:η1,η1 manner. Solvent-vapour-assisted conversion between the polymorphic coordination polymers and solvent-vapour influence on the conversion of coordination polymers 1 to 2a and 2b is also explored. The transformations have been examined and confirmed by X-ray diffraction, NMR spectroscopy and thermal analyses, including in situ diffraction studies of some transformations. PMID:25866656

  11. Solvent-vapour-assisted pathways and the role of pre-organization in solid-state transformations of coordination polymers.

    PubMed

    Wright, James S; Vitórica-Yrezábal, Iñigo J; Adams, Harry; Thompson, Stephen P; Hill, Adrian H; Brammer, Lee

    2015-03-01

    A family of one-dimensional coordination polymers, [Ag4(O2C(CF2)2CF3)4(phenazine)2(arene) n ]·m(arene), 1 (arene = toluene or xylene), have been synthesized and crystallographically characterized. Arene guest loss invokes structural transformations to yield a pair of polymorphic coordination polymers [Ag4(O2C(CF2)2CF3)4(phenazine)2], 2a and/or 2b , with one- and two-dimensional architectures, respectively. The role of pre-organization of the polymer chains of 1 in the selectivity for formation of either polymorph is explored, and the templating effect of toluene and p-xylene over o-xylene or m-xylene in the formation of arene-containing architecture 1 is also demonstrated. The formation of arene-free phase 2b , not accessible in a phase-pure form through other means, is shown to be the sole product of loss of toluene from 1-tol·tol [Ag4(O2C(CF2)2CF3)4(phenazine)2(toluene)]·2(toluene), a phase containing toluene coordinated to Ag(I) in an unusual μ:η(1),η(1) manner. Solvent-vapour-assisted conversion between the polymorphic coordination polymers and solvent-vapour influence on the conversion of coordination polymers 1 to 2a and 2b is also explored. The transformations have been examined and confirmed by X-ray diffraction, NMR spectroscopy and thermal analyses, including in situ diffraction studies of some transformations. PMID:25866656

  12. Solvent induced synthesis, structure and properties of coordination polymers based on 5-hydroxyisophthalic acid as linker and 1,10-phenanthroline as auxiliary ligand

    NASA Astrophysics Data System (ADS)

    Kariem, Mukaddus; Yawer, Mohd; Sheikh, Haq Nawaz

    2015-11-01

    Three new coordination polymers [Mn(hip)(phen) (H2O)]n (1), [Co(hip)(phen) (H2O)]n (2), and [Cd(hip) (phen) (H2O)]n (3) (H2hip=5-hydroxyisophthalic acid; phen=1,10-phenanthroline) have been synthesized by solvo-hydrothermal method using diethyl formamide-water (DEF-H2O) as solvent system. Single-crystal X-ray diffraction analysis reveals that all three coordination polymers 1, 2 and 3 crystallize in monoclinic space group P2/n. Metal ions are inter-connected by hydroxyisophthalate anions forming zig-zag 1D chain. 1D chains are further inter-connected by hydrogen bonding and π-π stacking interactions leading to 3D supramolecular architecture. Hydrogen-bonding and π-π stacking provide thermal stability to polymers. Compounds 1 and 2 are paramagnetic at room temperature and variable temperature magnetic moment measurements revealed weak ferromagnetic interactions between metal ions at low temperature. Compound 3 exhibits excellent photoluminescence with large Stokes shift.

  13. Two new coordination polymers, a trinuclear metal complex and their interconversion depending on the solvent.

    PubMed

    Koike, Shiori; Hirakawa, Takeshi; Yamanishi, Katsunori; Kondo, Mitsuru

    2014-09-14

    Two new 1-D coordination polymers and a discrete trinuclear complex with a double-ring framework were synthesized and structurally characterized. The unique irreversible conversion from one of the 1-D coordination polymers to the trinuclear complex by contact with MeCN is described.

  14. Strength and weaknesses of modeling the dynamics of mode-locked lasers by means of collective coordinates

    NASA Astrophysics Data System (ADS)

    Alsaleh, M.; Mback, C. B. L.; Tchomgo Felenou, E.; Tchofo Dinda, P.; Grelu, Ph; Porsezian, K.

    2016-07-01

    We address the efficiency of theoretical tools used in the development and optimization of mode-locked fiber lasers. Our discussion is based on the practical case of modeling the dynamics of a dispersion-managed fiber laser. One conventional approach uses discrete propagation equations, followed by the analysis of the numerical results through a collective coordinate projection. We compare the latter with our dynamical collective coordinate approach (DCCA), which combines both modeling and analysis in a compact form. We show that for single pulse dynamics, the DCCA allows a much quicker solution mapping in the space of cavity parameters than the conventional approach, along with a good accuracy. We also discuss the weaknesses of the DCCA, in particular when multiple pulsing bifurcations occur.

  15. Computational, electrochemical, and spectroscopic studies of two mononuclear cobaloximes: the influence of an axial pyridine and solvent on the redox behaviour and evidence for pyridine coordination to cobalt(i) and cobalt(ii) metal centres.

    PubMed

    Lawrence, Mark A W; Celestine, Michael J; Artis, Edward T; Joseph, Lorne S; Esquivel, Deisy L; Ledbetter, Abram J; Cropek, Donald M; Jarrett, William L; Bayse, Craig A; Brewer, Matthew I; Holder, Alvin A

    2016-06-21

    [Co(dmgBF2)2(H2O)2] (where dmgBF2 = difluoroboryldimethylglyoximato) was used to synthesize [Co(dmgBF2)2(H2O)(py)]·0.5(CH3)2CO (where py = pyridine) in acetone. The formulation of complex was confirmed by elemental analysis, high resolution MS, and various spectroscopic techniques. The complex [Co(dmgBF2)2(solv)(py)] (where solv = solvent) was readily formed in situ upon the addition of pyridine to complex . A spectrophotometric titration involving complex and pyridine proved the formation of such a species, with formation constants, log K = 5.5, 5.1, 5.0, 4.4, and 3.1 in 2-butanone, dichloromethane, acetone, 1,2-difluorobenzene/acetone (4 : 1, v/v), and acetonitrile, respectively, at 20 °C. In strongly coordinating solvents, such as acetonitrile, the lower magnitude of K along with cyclic voltammetry, NMR, and UV-visible spectroscopic measurements indicated extensive dissociation of the axial pyridine. In strongly coordinating solvents, [Co(dmgBF2)2(solv)(py)] can only be distinguished from [Co(dmgBF2)2(solv)2] upon addition of an excess of pyridine, however, in weakly coordinating solvents the distinctions were apparent without the need for excess pyridine. The coordination of pyridine to the cobalt(ii) centre diminished the peak current at the Epc value of the Co(I/0) redox couple, which was indicative of the relative position of the reaction equilibrium. Herein we report the first experimental and theoretical (59)Co NMR spectroscopic data for the formation of Co(i) species of reduced cobaloximes in the presence and absence of py (and its derivatives) in CD3CN. From spectroelectrochemical studies, it was found that pyridine coordination to a cobalt(i) metal centre is more favourable than coordination to a cobalt(ii) metal centre as evident by the larger formation constant, log K = 4.6 versus 3.1, respectively, in acetonitrile at 20 °C. The electrosynthesis of hydrogen by complexes and in various solvents demonstrated the dramatic effects of the axial

  16. Computational, electrochemical, and spectroscopic studies of two mononuclear cobaloximes: the influence of an axial pyridine and solvent on the redox behaviour and evidence for pyridine coordination to cobalt(i) and cobalt(ii) metal centres.

    PubMed

    Lawrence, Mark A W; Celestine, Michael J; Artis, Edward T; Joseph, Lorne S; Esquivel, Deisy L; Ledbetter, Abram J; Cropek, Donald M; Jarrett, William L; Bayse, Craig A; Brewer, Matthew I; Holder, Alvin A

    2016-06-21

    [Co(dmgBF2)2(H2O)2] (where dmgBF2 = difluoroboryldimethylglyoximato) was used to synthesize [Co(dmgBF2)2(H2O)(py)]·0.5(CH3)2CO (where py = pyridine) in acetone. The formulation of complex was confirmed by elemental analysis, high resolution MS, and various spectroscopic techniques. The complex [Co(dmgBF2)2(solv)(py)] (where solv = solvent) was readily formed in situ upon the addition of pyridine to complex . A spectrophotometric titration involving complex and pyridine proved the formation of such a species, with formation constants, log K = 5.5, 5.1, 5.0, 4.4, and 3.1 in 2-butanone, dichloromethane, acetone, 1,2-difluorobenzene/acetone (4 : 1, v/v), and acetonitrile, respectively, at 20 °C. In strongly coordinating solvents, such as acetonitrile, the lower magnitude of K along with cyclic voltammetry, NMR, and UV-visible spectroscopic measurements indicated extensive dissociation of the axial pyridine. In strongly coordinating solvents, [Co(dmgBF2)2(solv)(py)] can only be distinguished from [Co(dmgBF2)2(solv)2] upon addition of an excess of pyridine, however, in weakly coordinating solvents the distinctions were apparent without the need for excess pyridine. The coordination of pyridine to the cobalt(ii) centre diminished the peak current at the Epc value of the Co(I/0) redox couple, which was indicative of the relative position of the reaction equilibrium. Herein we report the first experimental and theoretical (59)Co NMR spectroscopic data for the formation of Co(i) species of reduced cobaloximes in the presence and absence of py (and its derivatives) in CD3CN. From spectroelectrochemical studies, it was found that pyridine coordination to a cobalt(i) metal centre is more favourable than coordination to a cobalt(ii) metal centre as evident by the larger formation constant, log K = 4.6 versus 3.1, respectively, in acetonitrile at 20 °C. The electrosynthesis of hydrogen by complexes and in various solvents demonstrated the dramatic effects of the axial

  17. Solvent-regulated assemblies of four Zn(II) coordination polymers constructed by flexible tetracarboxylates and pyridyl ligands

    NASA Astrophysics Data System (ADS)

    Fang, Kang; He, Xiang; Shao, Min; Li, Ming-Xing

    2016-08-01

    Four unique complexes with diverse coordination architectures were synthesized upon complexation of 5,5-(1,4-phenylenebis (methylene))bis (oxy)- diisophthalic acid (H4L) with zinc ions by using different solvent. namely, {[Zn(H2L) (bpp)]·DEF}n (1), {[Zn2(L) (bpp)2]·4H2O}n (2), {[Zn2(L) (pdp)2]·3H2O·DEF}n (3), {[Zn2(L) (pdp)2].4H2O}n (4). Complexes 1,2 and 3,4 are obtained by varying solvents to control their structures. The size of solvent molecular plays an important role to control different structure of these compounds. Compound 1 is 2D waved framework with (4, 4) grid layer as sql topology. Compound 3 displays a (4,6)-connected 2-nodal net with a fsc topology. Compounds 2 and 4 are all three-dimensional network simplified as (4,4)-connected 2-nodal net with a bbf topology. The photochemical properties of compounds 1-4 were tested in the solid state at room temperature, owing to their strong luminescent emissions, complexes 1-4 are good candidates for photoactive materials.

  18. Weak coordination among petiole, leaf, vein, and gas-exchange traits across Australian angiosperm species and its possible implications.

    PubMed

    Gleason, Sean M; Blackman, Chris J; Chang, Yvonne; Cook, Alicia M; Laws, Claire A; Westoby, Mark

    2016-01-01

    Close coordination between leaf gas exchange and maximal hydraulic supply has been reported across diverse plant life forms. However, it has also been suggested that this relationship may become weak or break down completely within the angiosperms. We examined coordination between hydraulic, leaf vein, and gas-exchange traits across a diverse group of 35 evergreen Australian angiosperms, spanning a large range in leaf structure and habitat. Leaf-specific conductance was calculated from petiole vessel anatomy and was also measured directly using the rehydration technique. Leaf vein density (thought to be a determinant of gas exchange rate), maximal stomatal conductance, and net CO 2 assimilation rate were also measured for most species (n = 19-35). Vein density was not correlated with leaf-specific conductance (either calculated or measured), stomatal conductance, nor maximal net CO 2 assimilation, with r (2) values ranging from 0.00 to 0.11, P values from 0.909 to 0.102, and n values from 19 to 35 in all cases. Leaf-specific conductance calculated from petiole anatomy was weakly correlated with maximal stomatal conductance (r (2) = 0.16; P = 0.022; n = 32), whereas the direct measurement of leaf-specific conductance was weakly correlated with net maximal CO 2 assimilation (r (2) = 0.21; P = 0.005; n = 35). Calculated leaf-specific conductance, xylem ultrastructure, and leaf vein density do not appear to be reliable proxy traits for assessing differences in rates of gas exchange or growth across diverse sets of evergreen angiosperms.

  19. Weak coordination among petiole, leaf, vein, and gas-exchange traits across Australian angiosperm species and its possible implications.

    PubMed

    Gleason, Sean M; Blackman, Chris J; Chang, Yvonne; Cook, Alicia M; Laws, Claire A; Westoby, Mark

    2016-01-01

    Close coordination between leaf gas exchange and maximal hydraulic supply has been reported across diverse plant life forms. However, it has also been suggested that this relationship may become weak or break down completely within the angiosperms. We examined coordination between hydraulic, leaf vein, and gas-exchange traits across a diverse group of 35 evergreen Australian angiosperms, spanning a large range in leaf structure and habitat. Leaf-specific conductance was calculated from petiole vessel anatomy and was also measured directly using the rehydration technique. Leaf vein density (thought to be a determinant of gas exchange rate), maximal stomatal conductance, and net CO 2 assimilation rate were also measured for most species (n = 19-35). Vein density was not correlated with leaf-specific conductance (either calculated or measured), stomatal conductance, nor maximal net CO 2 assimilation, with r (2) values ranging from 0.00 to 0.11, P values from 0.909 to 0.102, and n values from 19 to 35 in all cases. Leaf-specific conductance calculated from petiole anatomy was weakly correlated with maximal stomatal conductance (r (2) = 0.16; P = 0.022; n = 32), whereas the direct measurement of leaf-specific conductance was weakly correlated with net maximal CO 2 assimilation (r (2) = 0.21; P = 0.005; n = 35). Calculated leaf-specific conductance, xylem ultrastructure, and leaf vein density do not appear to be reliable proxy traits for assessing differences in rates of gas exchange or growth across diverse sets of evergreen angiosperms. PMID:26811791

  20. Transgenic expression of an expanded (GCG)13 repeat PABPN1 leads to weakness and coordination defects in mice.

    PubMed

    Dion, Patrick; Shanmugam, Vijayalakshmi; Gaspar, Claudia; Messaed, Christiane; Meijer, Inge; Toulouse, André; Laganiere, Janet; Roussel, Julie; Rochefort, Daniel; Laganiere, Simon; Allen, Carol; Karpati, George; Bouchard, Jean-Pierre; Brais, Bernard; Rouleau, Guy A

    2005-04-01

    Oculopharyngeal muscular dystrophy (OPMD) is a late-onset disorder caused by a (GCG)n trinucleotide repeat expansion in the poly(A) binding protein nuclear-1 (PABPN1) gene, which in turn leads to an expanded polyalanine tract in the protein. We generated transgenic mice expressing either the wild type or the expanded form of human PABPN1, and transgenic animals with the expanded form showed clear signs of abnormal limb clasping, muscle weakness, coordination deficits, and peripheral nerves alterations. Analysis of mitotic and postmitotic tissues in those transgenic animals revealed ubiquitinated PABPN1-positive intranuclear inclusions (INIs) in neuronal cells. This latter observation led us to test and confirm the presence of similar INIs in postmortem brain sections from an OPMD patient. Our results indicate that expanded PABPN1, presumably via the toxic effects of its polyalanine tract, can lead to inclusion formation and neurodegeneration in both the mouse and the human.

  1. Mono/bimetallic water-stable lanthanide coordination polymers as luminescent probes for detecting cations, anions and organic solvent molecules.

    PubMed

    Wang, Huarui; Qin, Jianhua; Huang, Chao; Han, Yanbing; Xu, Wenjuan; Hou, Hongwei

    2016-08-01

    Eleven water-stable isostructural mono/bimetallic lanthanide coordination polymers (Ln-CPs) {[EuxTb1-x (HL)(H2O)3]·H2O}n (x = 1.0 (1), 0.9 (3), 0.8 (4), 0.7 (5), 0.6 (6), 0.4 (7), 0.3 (8), 0.2 (9), 0.1 (10), 0.05 (11), 0 (2), H4L = 5,5'-(1H-2,3,5-triazole-1,4-diyl)diisophthalic acid) with uncoordinated Lewis basic triazole sites within the pores were prepared. The Ln-CPs represented by 1 showed a rapid and drastic emission quenching induced by external Fe(3+) and Cr(3+) cations and CrO4(2-) and CO3(2-) anions in aqueous solution. In addition, because of the comparable emission intensities of Eu(3+) and Tb(3+) ions, bimetallic CP 8 can be used as a ratiometric luminescent sensor for organic solvent molecules. Moreover, the luminescent color of the 8 sensor in pyridine and in other guest solvents undergoes obvious changes that can be clearly distinguished by the naked eye. PMID:27443408

  2. Exchange of Coordinated Solvent During Crystallization of a Metal-Organic Framework Observed by In Situ High-Energy X-ray Diffraction.

    PubMed

    Wu, Yue; Breeze, Matthew I; Clarkson, Guy J; Millange, Franck; O'Hare, Dermot; Walton, Richard I

    2016-04-11

    Using time-resolved monochromatic high energy X-ray diffraction, we present an in situ study of the solvothermal crystallisation of a new MOF [Yb2(BDC)3(DMF)2]⋅H2O (BDC=benzene-1,4-dicarboxylate and DMF=N,N-dimethylformamide) under solvothermal conditions, from mixed water/DMF solvent. Analysis of high resolution powder patterns obtained reveals an evolution of lattice parameters and electron density during the crystallisation process and Rietveld analysis shows that this is due to a gradual topochemical replacement of coordinated solvent molecules. The water initially coordinated to Yb(3+) is replaced by DMF as the reaction progresses. PMID:26959076

  3. The investigation of the solvent effect on coordination of nicotinato ligand with cobalt(II) complex containing tris(2-benzimidazolylmethyl)amine: A computational study

    NASA Astrophysics Data System (ADS)

    Sayin, Koray; Karakaş, Duran

    2014-11-01

    The electronic structure of [Co(ntb)(nic)]+ complex ion are optimized by using density functional theory (DFT) method with mix basis set. Where (ntb) represents tris(2-benzimidazolylmethyl)amine ligand and (nic) is the anion of nicotinic acids. Six different fields, vacuum, chloroform, butanonitrile, methanol, water and formamide solvents are used in these calculations. The calculated structural parameters indicate that (nic) ligand coordinates to cobalt(II) containing (ntb) ligand with one oxygen atom in butanonitrile, methanol, water and formamide solvents but coordinates with two oxygen atoms in vacuum. These results are supported with IR, UV and 1H NMR spectra. According to the calculated results, the geometry of [Co(ntb)(nic)]+ complex ion is distorted octahedral in vacuum while the geometry is distorted square pyramidal in the all other solvents. Distorted octahedral [Co(ntb)(nic)]+ complex ion have not been synthesized as experimentally and it is predicted with computational chemistry methods.

  4. Design and synthesis of two luminescent Zn(II)-based coordination polymers with different structures regulated by different solvent system

    NASA Astrophysics Data System (ADS)

    Wu, Wei-Ping; Wen, Gui-Lin; Liao, Yi; Wang, Jun; Lu, Lu; Wu, Yu; Xie, Bin

    2016-08-01

    Two new coordination polymers (CPs) [Zn(HL)(H2O)]n (1) and [Zn3(L)2(H2O)2]n·(H2O)n (2), based on a multifunctional ligand combined carboxylate groups and a nitrogen donor group 5-(6-carboxypyridin-2-yl)isophthalic acid (H3L), have been synthesized under different solvent media and fully characterized by powder X-ray diffraction (PXRD), infrared (IR) spectra, elemental analyses (EA) and thermogravimetric analyses (TGA). Single-crystal X-ray diffraction analysis reveals that 1 shows 1D dimeric chain structure, while 2 gives a 3D dense packing framework. Topology analysis illustrates that 2 can be simplified as a 3-nodal net (4, 5, 6-connected net) with the point symbol of {44·62}{46·64}2{48·66·8}. In addition, solid state luminescent properties of two complexes have also been studied in detail, which may act as the potential optical materials.

  5. Assembly of 4-, 6- and 8-connected Cd(II) pseudo-polymorphic coordination polymers: Synthesis, solvent-dependent structural variation and properties

    NASA Astrophysics Data System (ADS)

    Li, Zhao-Hao; Xue, Li-Ping; Miao, Shao-Bin; Zhao, Bang-Tun

    2016-08-01

    The reaction of Cd(NO3)2·4H2O, 2,5-thiophenedicarboxylic acid (H2tdc) and 1,2-bis(imidazol-1‧-yl)methane (bimm) by modulating solvent systems yielded three highly connected pseudo-polymorphic coordination polymers based on different dinuclear [Cd2(CO2)2] subunits bridged by carboxylate groups. Single crystal structural analyses reveal structural variation from 4-connected 2D sql layer, 6-connected 2-fold interpenetrated 3D pcu to 8-connected 3D bcu-type network in compounds 1-3. The structural dissimilarity in the structures dependent on the coordination environments of Cd(II) ions and linking modes of mixed ligand influenced by different solvent systems during the synthesis process. Moreover, thermogravimetric and photoluminescence behaviors of 1-3 were also investigated for the first time, and all the complexes emit blue luminescence in the solid state.

  6. Tuning the structure and magnetism of heterometallic sodium(1+)-cobalt(2+) formate coordination polymers by varying the metal ratio and solvents.

    PubMed

    Zhao, Jiong-Peng; Han, Song-De; Zhao, Ran; Yang, Qian; Chang, Ze; Bu, Xian-He

    2013-03-18

    Three new heterometallic formate coordination polymers formulated as [Na2Co(HCOO)4]∞ (1), [NaCo(HCOO)3]∞ (2), and [Na2Co7(HCOO)16]∞ (3) were obtained by adjusting the solvent and ratio of the reactants. In 1, a (4,4) cobalt formate layer is formed and the sodium ions connect the layers to form a three-dimensional (3D) framework. In 2, each formate ligand binds two Co(2+) and two Na(+) ions with a syn,syn,anti,anti coordination mode to form a chrial network with 4,6-connected topology. 3 is a Na(+)-ion-linked 3D framework based on the cobalt formate layer, which has a 10-membered metal ring. Magnetic studies indicate the existence of ferromagnetic interactions between adjacent Co(2+) ions in 1, while dominating antiferromagnetic couplings in 2 and 3.

  7. Part I. Student success in intensive versus traditional introductory chemistry courses. Part II. Synthesis of salts of the weakly coordinating trisphat anion

    NASA Astrophysics Data System (ADS)

    Hall, Mildred V.

    Part I. Intensive courses have been shown to be associated with equal or greater student success than traditional-length courses in a wide variety of disciplines and education levels. Student records from intensive and traditional-length introductory general chemistry courses were analyzed to determine the effects, of the course format, the level of academic experience, life experience (age), GPA, academic major and gender on student success in the course. Pretest scores, GPA and ACT composite scores were used as measures of academic ability and prior knowledge; t-tests comparing the means of these variables were used to establish that the populations were comparable prior to the course. Final exam scores, total course points and pretest-posttest differences were used as measures of student success; t-tests were used to determine if differences existed between the populations. ANCOVA analyses revealed that student GPA, pretest scores and course format were the only variables tested that were significant in accounting for the variance of the academic success measures. In general, the results indicate that students achieved greater academic success in the intensive-format course, regardless of the level of academic experience, life experience, academic major or gender. Part II. Weakly coordinating anions have many important applications, one of which is to function as co-catalysts in the polymerization of olefins by zirconocene. The structure of tris(tetrachlorobenzenedialato) phosphate(V) or "trisphat" anion suggests that it might be an outstanding example of a weakly coordinating anion. Trisphat acid was synthesized and immediately used to prepare the stable tributylammonium trisphat, which was further reacted to produce trisphat salts of Group I metal cations in high yields. Results of the 35Cl NQR analysis of these trisphat salts indicate only very weak coordination between the metal cations and the chlorine atoms of the trisphat anion.

  8. A New Family of Anionic Fe(III) Spin Crossover Complexes Featuring a Weak-Field N2O4 Coordination Octahedron.

    PubMed

    Takahashi, Kazuyuki; Kawamukai, Kiko; Okai, Mitsunobu; Mochida, Tomoyuki; Sakurai, Takahiro; Ohta, Hitoshi; Yamamoto, Takashi; Einaga, Yasuaki; Shiota, Yoshihito; Yoshizawa, Kazunari

    2016-01-22

    Unprecedented anionic Fe(III) spin crossover (SCO) complexes involving a weak-field O,N,O-tridentate ligand were discovered. The SCO transition was evidenced by the temperature variations in magnetic susceptibility, Mössbauer spectrum, and coordination structure. The DFT calculations suggested that larger coefficients on the azo group in the HOMO-1 of a ligand might contribute to the enhancement of a ligand-field splitting energy. The present anionic SCO complex also exhibited the light- induced excited-spin-state trapping effect. PMID:26642040

  9. Silver-free activation of ligated gold(I) chlorides: the use of [Me3NB12Cl11]- as a weakly coordinating anion in homogeneous gold catalysis.

    PubMed

    Wegener, Michael; Huber, Florian; Bolli, Christoph; Jenne, Carsten; Kirsch, Stefan F

    2015-01-12

    Phosphane and N-heterocyclic carbene ligated gold(I) chlorides can be effectively activated by Na[Me3NB12Cl11] (1) under silver-free conditions. This activation method with a weakly coordinating closo-dodecaborate anion was shown to be suitable for a large variety of reactions known to be catalyzed by homogeneous gold species, ranging from carbocyclizations to heterocyclizations. Additionally, the capability of 1 in a previously unknown conversion of 5-silyloxy-1,6-allenynes was demonstrated.

  10. Micromolding of a Highly Fluorescent Reticular Coordination Polymer: Solvent-Mediated Reconfigurable Polymerization in a Soft Lithographic Mold

    SciTech Connect

    Y You; H Yang; J Chung; J Kim; Y Jung; S Park

    2011-12-31

    Coordination polymerization of pyridine-based ligands and zinc or silver ions was controlled by soft lithographic micromolding in capillaries. The polymer patterns that are produced are highly fluorescent and supramolecularly structured.

  11. Coordination-Enabled One-Step Assembly of Ultrathin, Hybrid Microcapsules with Weak pH-Response.

    PubMed

    Yang, Chen; Wu, Hong; Yang, Xiao; Shi, Jiafu; Wang, Xiaoli; Zhang, Shaohua; Jiang, Zhongyi

    2015-05-01

    In this study, an ultrathin, hybrid microcapsule is prepared though coordination-enabled one-step assembly of tannic acid (TA) and titanium(IV) bis(ammonium lactate) dihydroxide (Ti-BALDH) upon a hard-templating method. Briefly, the PSS-doped CaCO3 microspheres with a diameter of 5-8 μm were synthesized and utilized as the sacrificial templates. Then, TA-Ti(IV) coatings were formed on the surface of the PSS-doped CaCO3 templates through soaking in TA and Ti-BALDH aqueous solutions under mild conditions. After removing the template by EDTA treatment, the TA-Ti(IV) microcapsules with a capsule wall thickness of 15 ± 3 nm were obtained. The strong coordination bond between polyphenol and Ti(IV) conferred the TA-Ti(IV) microcapsules high structural stability in the range of pH values 3.0-11.0. Accordingly, the enzyme-immobilized TA-Ti(IV) microcapsules exhibited superior pH and thermal stabilities. This study discloses the formation of TA-Ti(IV) microcapsules that are suitable for use as supports in catalysis due to their extensive pH and thermal stabilities.

  12. Solvent-induced synthesis of cobalt(II) coordination polymers based on a rigid ligand and flexible carboxylic acid ligands: syntheses, structures and magnetic properties.

    PubMed

    Wang, Ting; Zhang, Chuanlei; Ju, Zemin; Zheng, Hegen

    2015-04-21

    Five new cobalt(ii) coordination architectures, {[Co(L)2(H2O)2]·2H2O·2NO3}n (), {[Co(L)(ppda)]·2H2O}n (), {[Co2(L)(ppda)2]2·H2O}n (), {[Co(L)(nba)]·5H2O}n (), and {[Co(L)(oba)]2·3H2O}n (), have been constructed from the rigid ligand L [L = 2,8-di(1H-imidazol-1-yl)dibenzofuran] and different flexible carboxylic acid ligands [H2ppda = 4,4'-(perfluoropropane-2,2-diyl)dibenzoic acid, H2nba = 4,4'-azanediyldibenzoic acid, and H2oba = 4,4'-oxydibenzoic acid]. Depending on the nature of the solvent systems, these five different coordination polymers were synthesized and characterized by single-crystal X-ray diffraction, IR, PXRD and elemental analysis. Compounds , and were obtained by a one-pot method, and then we utilized the solvent-induced effect to obtain almost pure crystals of , respectively. Compound is an infinite 1D chain which is formed by L ligands and Co atoms. Compound contains a [Co2(CO2)4] secondary building unit (SBU), and can be topologically represented as a 6-connected 2-fold interpenetrating pcu net with the point symbol of {4(12)·6(3)}. Compound can be characterized as a 4-connected sql tetragonal planar network with the point symbol of {4(4)·6(2)}. In compounds and , there is a 1D chain which is formed by flexible carboxylic acid ligands and Co atoms; then the 1D chain is linked by L ligands in the tilting direction, leading to the formation of a 2D layer. Furthermore, UV-vis, TGA and magnetic properties have been investigated in detail. PMID:25778448

  13. The role of weak hydrogen and halogen bonding interactions in the assembly of a series of Hg(II) coordination polymers.

    PubMed

    Azhdari Tehrani, Alireza; Morsali, Ali; Kubicki, Maciej

    2015-03-28

    A series of eight new Hg(II) complexes based on the L4-X ligands, where L is (E) -4-halo-N-(pyridin-4-ylmethylene)aniline, were synthesized and characterized and their supramolecular crystal structures were studied by different geometrical and theoretical methods. Our study reveals the role of weak intermolecular interactions involving halogens, such as C–H∙∙∙X hydrogen bonds (in the cases of 1, 2, 3, 5, 6 and 7) and C–X∙∙∙X′–M halogen bonds (in the cases of 4 and 8), in the structural changes of supramolecular assemblies of coordination compounds. Complexes 1–8 were also synthesized by sonochemical irradiation and the morphology of the prepared complexes was investigated using FE-SEM. The BFDH analysis helps us to compare the predicted morphology to that obtained under ultrasonication. This study may provide further insight into discovering the role of weak intermolecular interactions in the context of metallosupramolecular assembly.

  14. Analysis of solvent nucleophile isotope effects: evidence for concerted mechanisms and nucleophilic activation by metal coordination in nonenzymatic and ribozyme-catalyzed phosphodiester hydrolysis.

    PubMed

    Cassano, Adam G; Anderson, Vernon E; Harris, Michael E

    2004-08-17

    Heavy atom isotope effects are a valuable tool for probing chemical and enzymatic reaction mechanisms; yet, they are not widely applied to examine mechanisms of nucleophilic activation. We developed approaches for analyzing solvent (18)O nucleophile isotope effects ((18)k(nuc)) that allow, for the first time, their application to hydrolysis reactions of nucleotides and nucleic acids. Here, we report (18)k(nuc) for phosphodiester hydrolysis catalyzed by Mg(2+) and by the Mg(2+)-dependent RNase P ribozyme and deamination by the Zn(2+)-dependent protein enzyme adenosine deaminase (ADA). Because ADA incorporates a single solvent molecule into the product inosine, this reaction can be used to monitor solvent (18)O/(16)O ratios in complex reaction mixtures. This approach, combined with new methods for analysis of isotope ratios of nucleotide phosphates by whole molecule mass spectrometry, permitted determination of (18)k(nuc) for hydrolysis of thymidine 5'-p-nitrophenyl phosphate and RNA cleavage by the RNase P ribozyme. For ADA, an inverse (18)k(nuc) of 0.986 +/- 0.001 is observed, reflecting coordination of the nucleophile by an active site Zn(2+) ion and a stepwise mechanism. In contrast, the observed (18)k(nuc) for phosphodiester reactions were normal: 1.027 +/- 0.013 and 1.030 +/- 0.012 for the Mg(2+)- and ribozyme-catalyzed reactions, respectively. Such normal effects indicate that nucleophilic attack occurs in the rate-limiting step for these reactions, consistent with concerted mechanisms. However, these magnitudes are significantly less than the (18)k(nuc) observed for nucleophilic attack by hydroxide (1.068 +/- 0.007), indicating a "stiffer" bonding environment for the nucleophile in the transition state. Kinetic analysis of the Mg(2+)-catalyzed reaction indicates that a Mg(2+)-hydroxide complex is the catalytic species; thus, the lower (18)k(nuc), in large part, reflects direct metal ion coordination of the nucleophilic oxygen. A similar value for the RNase P

  15. Magnetic properties of weakly exchange-coupled high spin Co(II) ions in pseudooctahedral coordination evaluated by single crystal X-band EPR spectroscopy and magnetic measurements.

    PubMed

    Neuman, Nicolás I; Winkler, Elín; Peña, Octavio; Passeggi, Mario C G; Rizzi, Alberto C; Brondino, Carlos D

    2014-03-01

    We report single-crystal X-band EPR and magnetic measurements of the coordination polymer catena-(trans-(μ2-fumarato)tetraaquacobalt(II)), 1, and the Co(II)-doped Zn(II) analogue, 2, in different Zn:Co ratios. 1 presents two magnetically inequivalent high spin S = 3/2 Co(II) ions per unit cell, named A and B, in a distorted octahedral environment coordinated to four water oxygen atoms and trans coordinated to two carboxylic oxygen atoms from the fumarate anions, in which the Co(II) ions are linked by hydrogen bonds and fumarate molecules. Magnetic susceptibility and magnetization measurements of 1 indicate weak antiferromagnetic exchange interactions between the S = 3/2 spins of the Co(II) ions in the crystal lattice. Oriented single crystal EPR experiments of 1 and 2 were used to evaluate the molecular g-tensor and the different exchange coupling constants between the Co(II) ions, assuming an effective spin S′= 1/2. Unexpectedly, the eigenvectors of the molecular g-tensor were not lying along any preferential bond direction, indicating that, in high spin Co(II) ions in roughly octahedral geometry with approximately axial EPR signals, the presence of molecular pseudo axes in the metal site does not determine preferential directions for the molecular g-tensor. The EPR experiment and magnetic measurements, together with a theoretical analysis relating the coupling constants obtained from both techniques, allowed us to evaluate selectively the exchange coupling constant associated with hydrogen bonds that connect magnetically inequivalent Co(II) ions (|JAB(1/2)| = 0.055(2) cm(–1)) and the exchange coupling constant associated with a fumarate bridge connecting equivalent Co(II) ions (|JAA(1/2)| ≈ 0.25 (1) cm(–1)), in good agreement with the average J(3/2) value determined from magnetic measurements.

  16. Selective removal of alkali metal cations from multiply-charged ions via gas-phase ion/ion reactions using weakly coordinating anions.

    PubMed

    Luongo, Carl A; Bu, Jiexun; Burke, Nicole L; Gilbert, Joshua D; Prentice, Boone M; Cummings, Steven; Reed, Christopher A; McLuckey, Scott A

    2015-03-01

    Selective removal of alkali metal cations from mixed cation multiply-charged peptide ions is demonstrated here using gas-phase ion/ion reactions with a series of weakly coordinating anions (WCAs), including hexafluorophosphate (PF6 (-)), tetrakis[3,5-bis(trifluoromethyl)phenyl]borate (BARF), tetrakis(pentafluorophenyl)borate (TPPB), and carborane (CHB11Cl11 (-)). In all cases, a long-lived complex is generated by dication/anion condensation followed by ion activation to compare proton transfer with alkali ion transfer from the peptide to the anion. The carborane anion was the only anion studied to undergo dissociation exclusively through loss of the metallated anion, regardless of the studied metal adduct. All other anions studied yield varying abundances of protonated and metallated peptide depending on the peptide sequence and the metal identity. Density functional theory calculations suggest that for the WCAs studied, metal ion transfer is most strongly favored thermodynamically, which is consistent with the experimental results. The carborane anion is demonstrated to be a robust reagent for the selective removal of alkali metal cations from peptide cations with mixtures of excess protons and metal cations. PMID:25560986

  17. Selective Removal of Alkali Metal Cations from Multiply-Charged Ions via Gas-Phase Ion/Ion Reactions Using Weakly Coordinating Anions

    NASA Astrophysics Data System (ADS)

    Luongo, Carl A.; Bu, Jiexun; Burke, Nicole L.; Gilbert, Joshua D.; Prentice, Boone M.; Cummings, Steven; Reed, Christopher A.; McLuckey, Scott A.

    2015-03-01

    Selective removal of alkali metal cations from mixed cation multiply-charged peptide ions is demonstrated here using gas-phase ion/ion reactions with a series of weakly coordinating anions (WCAs), including hexafluorophosphate (PF6 -), tetrakis[3,5-bis(trifluoromethyl)phenyl]borate (BARF), tetrakis(pentafluorophenyl)borate (TPPB), and carborane (CHB11Cl11 -). In all cases, a long-lived complex is generated by dication/anion condensation followed by ion activation to compare proton transfer with alkali ion transfer from the peptide to the anion. The carborane anion was the only anion studied to undergo dissociation exclusively through loss of the metallated anion, regardless of the studied metal adduct. All other anions studied yield varying abundances of protonated and metallated peptide depending on the peptide sequence and the metal identity. Density functional theory calculations suggest that for the WCAs studied, metal ion transfer is most strongly favored thermodynamically, which is consistent with the experimental results. The carborane anion is demonstrated to be a robust reagent for the selective removal of alkali metal cations from peptide cations with mixtures of excess protons and metal cations.

  18. Dissolution of metal salts in bis(trifluoromethylsulfonyl)imide-based ionic liquids: studying the affinity of metal cations toward a "weakly coordinating" anion.

    PubMed

    Bortolini, Olga; Chiappe, Cinzia; Ghilardi, Tiziana; Massi, Alessandro; Pomelli, Christian Silvio

    2015-05-28

    Despite the weakly coordinating ability of the bis(trifluoromethylsulfonyl)imide anion ([Tf2N](-)) the corresponding ionic liquids (ILs) are able to dissolve relevant amounts of metal salts having the same anion, M[Tf2N]x. To better understand the metal dissolution process we evaluated the interaction ability of a set of metal cations (Y(III), Al(III), Co(II), Ni(II), Cu(II), Zn(II), Ag(I), Li(I), and Na(I)) toward the [Tf2N](-) anion measuring the relative aptitude to give the corresponding anionic monocharged complex, [M(Tf2N)x+1](-) using the ESI-MS technique. UV-vis and NMR measurements were carried out to verify the consistence between the liquid and the gas phase. Density functional theory calculations have been used to identify the metal-containing species and determine their relative stability. An interesting correlation between interaction ability and chemical properties (Lewis acidity) was found.

  19. Dissolution of metal salts in bis(trifluoromethylsulfonyl)imide-based ionic liquids: studying the affinity of metal cations toward a "weakly coordinating" anion.

    PubMed

    Bortolini, Olga; Chiappe, Cinzia; Ghilardi, Tiziana; Massi, Alessandro; Pomelli, Christian Silvio

    2015-05-28

    Despite the weakly coordinating ability of the bis(trifluoromethylsulfonyl)imide anion ([Tf2N](-)) the corresponding ionic liquids (ILs) are able to dissolve relevant amounts of metal salts having the same anion, M[Tf2N]x. To better understand the metal dissolution process we evaluated the interaction ability of a set of metal cations (Y(III), Al(III), Co(II), Ni(II), Cu(II), Zn(II), Ag(I), Li(I), and Na(I)) toward the [Tf2N](-) anion measuring the relative aptitude to give the corresponding anionic monocharged complex, [M(Tf2N)x+1](-) using the ESI-MS technique. UV-vis and NMR measurements were carried out to verify the consistence between the liquid and the gas phase. Density functional theory calculations have been used to identify the metal-containing species and determine their relative stability. An interesting correlation between interaction ability and chemical properties (Lewis acidity) was found. PMID:25361174

  20. Versatile reactivity of a solvent-coordinated diiron(II) compound: synthesis and dioxygen reactivity of a mixed-valent Fe(II)Fe(III) species.

    PubMed

    Majumdar, Amit; Apfel, Ulf-Peter; Jiang, Yunbo; Moënne-Loccoz, Pierre; Lippard, Stephen J

    2014-01-01

    A new, DMF-coordinated, preorganized diiron compound [Fe2(N-Et-HPTB)(DMF)4](BF4)3 (1) was synthesized, avoiding the formation of [Fe(N-Et-HPTB)](BF4)2 (10) and [Fe2(N-Et-HPTB)(μ-MeCONH)](BF4)2 (11), where N-Et-HPTB is the anion of N,N,N',N'-tetrakis[2-(1-ethylbenzimidazolyl)]-2-hydroxy-1,3-diaminopropane. Compound 1 is a versatile reactant from which nine new compounds have been generated. Transformations include solvent exchange to yield [Fe2(N-Et-HPTB)(MeCN)4](BF4)3 (2), substitution to afford [Fe2(N-Et-HPTB)(μ-RCOO)](BF4)2 (3, R = Ph; 4, RCOO = 4-methyl-2,6-diphenyl benzoate]), one-electron oxidation by (Cp2Fe)(BF4) to yield a Robin-Day class II mixed-valent diiron(II,III) compound, [Fe2(N-Et-HPTB)(μ-PhCOO)(DMF)2](BF4)3 (5), two-electron oxidation with tris(4-bromophenyl)aminium hexachloroantimonate to generate [Fe2(N-Et-HPTB)Cl3(DMF)](BF4)2 (6), reaction with (2,2,6,6-tetramethylpiperidin-1-yl)oxyl to form [Fe5(N-Et-HPTB)2(μ-OH)4(μ-O)(DMF)2](BF4)4 (7), and reaction with dioxygen to yield an unstable peroxo compound that decomposes at room temperature to generate [Fe4(N-Et-HPTB)2(μ-O)3(H2O)2](BF4)·8DMF (8) and [Fe4(N-Et-HPTB)2(μ-O)4](BF4)2 (9). Compound 5 loses its bridging benzoate ligand upon further oxidation to form [Fe2(N-Et-HPTB)(OH)2(DMF)2](BF4)3 (12). Reaction of the diiron(II,III) compound 5 with dioxygen was studied in detail by spectroscopic methods. All compounds (1-12) were characterized by single-crystal X-ray structure determinations. Selected compounds and reaction intermediates were further examined by a combination of elemental analysis, electronic absorption spectroscopy, Mössbauer spectroscopy, EPR spectroscopy, resonance Raman spectroscopy, and cyclic voltammetry.

  1. Versatile Reactivity of a Solvent-Coordinated Diiron(II) Compound: Synthesis and Dioxygen Reactivity of a Mixed Valent FeIIFeIII Species

    PubMed Central

    Majumdar, Amit; Apfel, Ulf-Peter; Jiang, Yunbo; Moënne-Loccoz, Pierre; Lippard, Stephen J.

    2014-01-01

    A new, DMF-coordinated, pre-organized diiron compound [Fe2(N-Et-HPTB)(DMF)4](BF4)3 (1) was synthesized, avoiding the formation of [Fe(N-Et-HPTB)](BF4)2 (10) and [Fe2(N-Et-HPTB)(μ-MeCONH)](BF4)2 (11), where N-Et-HPTB is the anion of N,N,N’,N’-tetrakis(2-(1-ethylbenzimidazolyl))-2-hydroxy-1,3-diaminopropane. Compound 1 is a versatile reactant from which nine new compounds have been generated. Transformations include solvent exchange to yield [Fe2(N-Et-HPTB)(MeCN)4](BF4)3 (2), substitution to afford [Fe2(N-Et-HPTB)(μ-RCOO)](BF4)2 (3, R = Ph; 4, RCOO = 4-methyl-2,6-diphenyl benzoate]), one-electron oxidation by (Cp2Fe)(BF4) to yield a Robin-Day class II mixed valent diiron(II,III) compound, [Fe2(N-Et-HPTB)(μ-PhCOO)(DMF)2](BF4)3 (5), two-electron oxidation with tris(4-bromophenyl)aminium hexachloroantimonate to generate [Fe2(N-Et-HPTB)Cl3(DMF)](BF4)2 (6), reaction with TEMPO (2,2,6,6-tetramethylpiperidin-1-yl)oxyl) to form [Fe5(N-Et-HPTB)2(μ-OH)4(μ-O)(DMF)2](BF4)4 (7), and reaction with dioxygen to yield an unstable peroxo compound that decomposes at room temperature to generate [Fe4(N-Et-HPTB)2(μ-O)3(H2O)2](BF4)·8DMF (8) and [Fe4(N-Et-HPTB)2(μ-O)4](BF4)2 (9). Compound 5 loses its bridging benzoate ligand upon further oxidation to form [Fe2(N-Et-HPTB)(OH)2(DMF)2](BF4)3 (12). Reaction of the diiron(II,III) compound (5) with dioxygen was studied in detail by spectroscopic methods. All compounds (1-12) were characterized by single crystal X-ray structure determinations. Selected compounds and reaction intermediates were further examined by a combination of elemental analysis, electronic absorption spectroscopy, Mössbauer spectroscopy, EPR spectroscopy, resonance Raman spectroscopy, and cyclic voltammetry. PMID:24359397

  2. Interdependence of conformational and chemical reaction dynamics during ion assembly in polar solvents.

    PubMed

    Ji, Minbiao; Hartsock, Robert W; Sun, Zheng; Gaffney, Kelly J

    2011-10-01

    We have utilized time-resolved vibrational spectroscopy to study the interdependence of the conformational and chemical reaction dynamics of ion assembly in solution. We investigated the chemical interconversion dynamics of the LiNCS ion pair and the (LiNCS)(2) ion-pair dimer, as well as the spectral diffusion dynamics of these ionic assemblies. For the strongly coordinating Lewis base solvents benzonitrile, dimethyl carbonate, and ethyl acetate, we observe Li(+) coordination by both solvent molecules and NCS(-) anions, while the weak Lewis base solvent nitromethane shows no evidence for solvent coordination of Li(+) ions. The strong interaction between the ion-pair dimer structure and the Lewis base solvents leads to ion-pair dimer solvation dynamics that proceed more slowly than the ion-pair dimer dissociation. We have attributed the slow spectral diffusion dynamics to electrostatic reorganization of the solvent molecules coordinated to the Li(+) cations present in the ion-pair dimer structure and concluded that the dissociation of ion-pair dimers depends more critically on longer length scale electrostatic reorganization. This unusual inversion of the conformational and chemical reaction rates does not occur for ion-pair dimer dissociation in nitromethane or for ion pair association in any of the solvents.

  3. Higher coordinate gold(I) complexes with the weak Lewis base tri(4-fluorophenyl) phosphine. Synthesis, structural, luminescence, and DFT studies

    NASA Astrophysics Data System (ADS)

    Agbeworvi, George; Assefa, Zerihun; Sykora, Richard E.; Taylor, Jared; Crawford, Carlos

    2016-03-01

    The structures and spectroscopic properties of two high coordinate gold(I) phosphine complexes with the TFFPP=tri(4-fluorophenyl)phosphine ligand are reported. Synthesis in a 1:3 metal to ligand ratio provided the compound [AuCl(TFFPP)3] (2) that crystallize in the P 1 bar space group, where the asymmetric unit consists of three independent molecules. In all three sites, two sets of bond angles display distinctly different ranges. The three P-Au-P angles have average values of 117.92°, 117.57°, and 114.78° for sites A, B, and C, with the corresponding P-Au-Cl angles of 98.31°, 99.05°, and 103.38°, respectively. The chloride ion coordinates as the fourth ligand, at the corresponding Au-Cl distance of 2.7337, 2.6825, and 2.6951 Å for the three sites. This distance is longer by 0.40-0.45 Å than the Au-Cl distance found in the mono TFFPP complex 1 (2.285 Å) indicating a weakening of the Au-Cl interaction as the coordination number increases. In compound 3, [Au(TFFPP)3]Cl·½CH2Cl2·H2O, the structure consists of three phosphine ligands bound to the gold(I) atom, but the Cl- exists as uncoordinated counter anion. The structural differences observed in the two complexes are attributable to crystal-packing effects caused by the introduction of H-bonding as well as enhanced intra and inter-molecular π-interaction in 3. The photoluminescence of the complexes compared with that of the ligand show ligand centered emission perturbed by the metal coordination. Theoretical DFT studies conducted on these complexes supports assignments of the electronic transitions observed in these systems.

  4. Solvent-induced syntheses, crystal structures, magnetic properties, and single-crystal-to-single-crystal transformation of azido-Cu(II) coordination polymers with 2-naphthoic acid as co-ligand.

    PubMed

    Liu, Xiangyu; Cen, Peipei; Li, Hui; Ke, Hongshan; Zhang, Sheng; Wei, Qing; Xie, Gang; Chen, Sanping; Gao, Shengli

    2014-08-01

    Based on the solvent-induced effect, three new azido-copper coordination polymers--[Cu(2-na)(N3)] (1), [Cu(2-na)(N3)] (2), and [Cu(2-na)(N3)(C2H5OH)] (3) (where 2-na = 2-naphthoic acid)--have been successfully prepared. Structure analysis shows that the Cu(II) cations in compounds 1-3 present tetra-, penta-, and hexa-coordination geometries, respectively. Compound 1 is a well-isolated one-dimensional (1D) chain with the EO-azido group, while 2 is an isomer of 1 and exhibits a two-dimensional (2D) layer involving the EE-azido group. Thermodynamically, density functional theory (DFT) calculation reveals that 2 occupies the stable state and 1 locates in the metastable state. Compound 3 consists of a 1D chain with triple bridging mode, which is derived from 1, and undergoes a single-crystal-to-single-crystal transformation by soaking in ethanol solvent; the powdery product of 1, namely 1b, could be yielded after the dealcoholization of compound 3. Magnetic measurements indicate that compounds 1-3 perform strong intrachain ferromagnetic interactions, experiencing long-range magnetic ordering and slow magnetic relaxation. Compound 1 features the metamagnetic behavior with a transition temperature of 15 K, while 2 and 3 display spin glass behavior with the phase transition temperatures of 15 and 12 K, respectively. Magneto-structure relationships are investigated as well.

  5. Reaction Mechanism for Direct Proton Transfer from Carbonic Acid to a Strong Base in Aqueous Solution II: Solvent Coordinate-Dependent Reaction Path.

    PubMed

    Daschakraborty, Snehasis; Kiefer, Philip M; Miller, Yifat; Motro, Yair; Pines, Dina; Pines, Ehud; Hynes, James T

    2016-03-10

    The protonation of methylamine base CH3NH2 by carbonic acid H2CO3 within a hydrogen (H)-bonded complex in aqueous solution was studied via Car-Parrinello dynamics in the preceding paper (Daschakraborty, S.; Kiefer, P. M.; Miller, Y.; Motro, Y.; Pines, D.; Pines, E.; Hynes, J. T. J. Phys. Chem. B 2016, DOI: 10.1021/acs.jpcb.5b12742). Here some important further details of the reaction path are presented, with specific emphasis on the water solvent's role. The overall reaction is barrierless and very rapid, on an ∼100 fs time scale, with the proton transfer (PT) event itself being very sudden (<10 fs). This transfer is preceded by the acid-base H-bond's compression, while the water solvent changes little until the actual PT occurrence; this results from the very strong driving force for the reaction, as indicated by the very favorable acid-protonated base ΔpKa difference. Further solvent rearrangement follows immediately the sudden PT's production of an incipient contact ion pair, stabilizing it by establishment of equilibrium solvation. The solvent water's short time scale ∼120 fs response to the incipient ion pair formation is primarily associated with librational modes and H-bond compression of water molecules around the carboxylate anion and the protonated base. This is consistent with this stabilization involving significant increase in H-bonding of hydration shell waters to the negatively charged carboxylate group oxygens' (especially the former H2CO3 donor oxygen) and the nitrogen of the positively charged protonated base's NH3(+). PMID:26876428

  6. Reaction Mechanism for Direct Proton Transfer from Carbonic Acid to a Strong Base in Aqueous Solution II: Solvent Coordinate-Dependent Reaction Path.

    PubMed

    Daschakraborty, Snehasis; Kiefer, Philip M; Miller, Yifat; Motro, Yair; Pines, Dina; Pines, Ehud; Hynes, James T

    2016-03-10

    The protonation of methylamine base CH3NH2 by carbonic acid H2CO3 within a hydrogen (H)-bonded complex in aqueous solution was studied via Car-Parrinello dynamics in the preceding paper (Daschakraborty, S.; Kiefer, P. M.; Miller, Y.; Motro, Y.; Pines, D.; Pines, E.; Hynes, J. T. J. Phys. Chem. B 2016, DOI: 10.1021/acs.jpcb.5b12742). Here some important further details of the reaction path are presented, with specific emphasis on the water solvent's role. The overall reaction is barrierless and very rapid, on an ∼100 fs time scale, with the proton transfer (PT) event itself being very sudden (<10 fs). This transfer is preceded by the acid-base H-bond's compression, while the water solvent changes little until the actual PT occurrence; this results from the very strong driving force for the reaction, as indicated by the very favorable acid-protonated base ΔpKa difference. Further solvent rearrangement follows immediately the sudden PT's production of an incipient contact ion pair, stabilizing it by establishment of equilibrium solvation. The solvent water's short time scale ∼120 fs response to the incipient ion pair formation is primarily associated with librational modes and H-bond compression of water molecules around the carboxylate anion and the protonated base. This is consistent with this stabilization involving significant increase in H-bonding of hydration shell waters to the negatively charged carboxylate group oxygens' (especially the former H2CO3 donor oxygen) and the nitrogen of the positively charged protonated base's NH3(+).

  7. Two Isostructural Coordination Polymers Showing Diverse Magnetic Behaviors: Weak Coupling (Ni(II)) and an Ordered Array of Single-Chain Magnets (Co(II)).

    PubMed

    Chen, Min; Zhao, Hui; Sañudo, E Carolina; Liu, Chun-Sen; Du, Miao

    2016-04-18

    Two isomorphic 3-D complexes with the formulas [M3(TPTA) (OH)2(H2O)4]n (M = Ni for 1 and Co for 2; H4TPTA = [1,1':4',1″-terphenyl]-2',3,3″,5'-tetracarboxylic acid) have been synthesized and magnetically characterized. Complexes 1 (Ni(II)) and 2 (Co(II)) have the same 1-D rod-shaped inorganic SBUs but exhibit significantly different magnetic properties. Complex 2(Co(II)) is a 3-D arrangement of a 1-D Co(II) single-chain magnet (SCM), while complex 1(Ni(II)) exhibits weak coupling. PMID:27022765

  8. Two Isostructural Coordination Polymers Showing Diverse Magnetic Behaviors: Weak Coupling (Ni(II)) and an Ordered Array of Single-Chain Magnets (Co(II)).

    PubMed

    Chen, Min; Zhao, Hui; Sañudo, E Carolina; Liu, Chun-Sen; Du, Miao

    2016-04-18

    Two isomorphic 3-D complexes with the formulas [M3(TPTA) (OH)2(H2O)4]n (M = Ni for 1 and Co for 2; H4TPTA = [1,1':4',1″-terphenyl]-2',3,3″,5'-tetracarboxylic acid) have been synthesized and magnetically characterized. Complexes 1 (Ni(II)) and 2 (Co(II)) have the same 1-D rod-shaped inorganic SBUs but exhibit significantly different magnetic properties. Complex 2(Co(II)) is a 3-D arrangement of a 1-D Co(II) single-chain magnet (SCM), while complex 1(Ni(II)) exhibits weak coupling.

  9. Fluoro- and perfluoralkylsulfonylpentafluoroanilides: synthesis and characterization of NH acids for weakly coordinating anions and their gas-phase and solution acidities.

    PubMed

    Kögel, Julius F; Linder, Thomas; Schröder, Fabian G; Sundermeyer, Jörg; Goll, Sascha K; Himmel, Daniel; Krossing, Ingo; Kütt, Karl; Saame, Jaan; Leito, Ivo

    2015-04-01

    Fluoro- and perfluoralkylsulfonyl pentafluoroanilides [HN(C6F5)(SO2X); X = F, CF3, C4F9, C8F17] are a class of imides with two different strongly electron-withdrawing substituents attached to a nitrogen atom. They are NH acids, the unsymmetrical hybrids of the well-known symmetrical bissulfonylimides and bispentafluorophenylamine. The syntheses, the structures of these perfluoroanilides, their solvates, and some selected lithium salts give rise to a structural variety beyond the symmetrical parent compounds. The acidities of representative subsets of these novel NH acids have been investigated experimentally and quantum-chemically and their gas-phase acidities (GAs) are reported, as well as the pKa values of these compounds in acetonitrile (MeCN) and DMSO solution. In quantum chemical investigations with the vertical and relaxed COSMO cluster-continuum models (vCCC/rCCC), the unusual situation is encountered that the DMSO-solvated acid Me2SO-H-N(SO2CF3)2, optimized in the gas phase (vCCC model), dissociates to Me2SO-H(+)-N(SO2CF3)2(-) during structural relaxation and full optimization with the solvation model turned on (rCCC model). This proton transfer underlines the extremely high acidity of HN(SO2CF3)2. The importance of this effect is studied computationally in DMSO and MeCN solution. Usually this effect is less pronounced in MeCN and is of higher importance in the more basic solvent DMSO. Nevertheless, the neglect of the structural relaxation upon solvation causes typical changes in the computational pKa values of 1 to 4 orders of magnitude (4-20 kJ mol(-1)). The results provide evidence that the published experimental DMSO pKa value of HN(SO2CF3)2 should rather be interpreted as the pKa of a Me2SO-H(+)-N(SO2CF3)2(-) contact ion pair. PMID:25727401

  10. Fluoro- and perfluoralkylsulfonylpentafluoroanilides: synthesis and characterization of NH acids for weakly coordinating anions and their gas-phase and solution acidities.

    PubMed

    Kögel, Julius F; Linder, Thomas; Schröder, Fabian G; Sundermeyer, Jörg; Goll, Sascha K; Himmel, Daniel; Krossing, Ingo; Kütt, Karl; Saame, Jaan; Leito, Ivo

    2015-04-01

    Fluoro- and perfluoralkylsulfonyl pentafluoroanilides [HN(C6F5)(SO2X); X = F, CF3, C4F9, C8F17] are a class of imides with two different strongly electron-withdrawing substituents attached to a nitrogen atom. They are NH acids, the unsymmetrical hybrids of the well-known symmetrical bissulfonylimides and bispentafluorophenylamine. The syntheses, the structures of these perfluoroanilides, their solvates, and some selected lithium salts give rise to a structural variety beyond the symmetrical parent compounds. The acidities of representative subsets of these novel NH acids have been investigated experimentally and quantum-chemically and their gas-phase acidities (GAs) are reported, as well as the pKa values of these compounds in acetonitrile (MeCN) and DMSO solution. In quantum chemical investigations with the vertical and relaxed COSMO cluster-continuum models (vCCC/rCCC), the unusual situation is encountered that the DMSO-solvated acid Me2SO-H-N(SO2CF3)2, optimized in the gas phase (vCCC model), dissociates to Me2SO-H(+)-N(SO2CF3)2(-) during structural relaxation and full optimization with the solvation model turned on (rCCC model). This proton transfer underlines the extremely high acidity of HN(SO2CF3)2. The importance of this effect is studied computationally in DMSO and MeCN solution. Usually this effect is less pronounced in MeCN and is of higher importance in the more basic solvent DMSO. Nevertheless, the neglect of the structural relaxation upon solvation causes typical changes in the computational pKa values of 1 to 4 orders of magnitude (4-20 kJ mol(-1)). The results provide evidence that the published experimental DMSO pKa value of HN(SO2CF3)2 should rather be interpreted as the pKa of a Me2SO-H(+)-N(SO2CF3)2(-) contact ion pair.

  11. An interconverting family of coordination cages and a meso-helicate; effects of temperature, concentration, and solvent on the product distribution of a self-assembly process.

    PubMed

    Cullen, William; Hunter, Christopher A; Ward, Michael D

    2015-03-16

    The self-assembly between a water-soluble bis-bidentate ligand L(18w) and Co(II) salts in water affords three high-spin Co(II) products: a dinuclear meso-helicate [Co2(L(18w))3]X4; a tetrahedral cage [Co4(L(18w))6]X8; and a dodecanuclear truncated-tetrahedral cage [Co12(L(18w))18]X24 (X = BF4 or ClO4). All three products were crystallized under different conditions and structurally characterized. In [Co2(L(18w))3]X4 all three bridging ligands span a pair of metal ions; in the two larger products, there is a metal ion at each vertex of the Co4 or Co12 polyhedral cage array with a bridging ligand spanning a pair of metal ions along every edge. All three structural types are known: what is unusual here is the presence of all three from the same reaction. The assemblies Co2, Co4, and Co12 are in slow equilibrium (hours/days) in aqueous solution, and this can be conveniently monitored by (1)H NMR spectroscopy because (i) the paramagnetism of Co(II) disperses the signals over a range of ca. 200 ppm and (ii) the different symmetries of the three species give characteristically different numbers of independent (1)H NMR signals, which makes identification easy. From temperature- and concentration-dependent (1)H NMR studies it is clear that increasing temperature and increasing dilution favors fragmentation to give a larger proportion of the smaller assemblies for entropic reasons. High concentrations and low temperature favor the larger assembly despite the unfavorable entropic and electrostatic factors associated with its formation. We suggest that this arises from the hydrophobic effect: reorganization of several smaller complexes into one larger one results in a smaller proportion of the hydrophobic ligand surface being exposed to water, with a larger proportion of the ligand surface protected in the interior of the assembly. In agreement with this, (1)H NMR spectra in a nonaqueous solvent (MeNO2) show formation of only [Co2(L(18w))3]X4 because the driving force for

  12. Color tunable and near white-light emission of two solvent-induced 2D lead(II) coordination networks based on a rigid ligand 1-tetrazole-4-imidazole-benzene.

    PubMed

    Chen, Jun; Zhang, Qing; Liu, Zhi-Fa; Wang, Shuai-Hua; Xiao, Yu; Li, Rong; Xu, Jian-Gang; Zhao, Ya-Ping; Zheng, Fa-Kun; Guo, Guo-Cong

    2015-06-01

    Two new lead(II) coordination polymers, [Pb(NO3)(tzib)]n (1) and [Pb(tzib)2]n (2), were successfully synthesized from the reaction of a rigid ligand 1-tetrazole-4-imidazole-benzene (Htzib) and lead(II) nitrate in different solvents. The obtained polymers have been characterized by single-crystal X-ray diffraction analyses, which show that both polymers feature 2D layer structures. The inorganic anion nitrate in 1 shows a μ2-κO3:κO3 bridging mode to connect adjacent lead ions into a zigzag chain, and then the organic ligands tzib(-) join the neighboring chains into a 2D layer by a μ3-κN1:κN2:κN6 connection mode. In 2, there are two different bridging modes of the tzib(-) ligand: μ3-κN1:κN2:κN6 and μ3-κN1:κN6 to coordinate the lead ions into a 2D layer structure. Interestingly, both polymers displayed broadband emissions covering the entire visible spectra, which could be tunable to near white-light emission by varying excitation wavelengths. PMID:25952460

  13. Solvent substitution

    SciTech Connect

    Not Available

    1990-01-01

    The DOE Environmental Restoration and Waste Management Office of Technology Development and the Air Force Engineering and Services Center convened the First Annual International Workshop on Solvent Substitution on December 4--7, 1990. The primary objectives of this joint effort were to share information and ideas among attendees in order to enhance the development and implementation of required new technologies for the elimination of pollutants associated with industrial use of hazardous and toxic solvents; and to aid in accelerating collaborative efforts and technology transfer between government and industry for solvent substitution. There were workshop sessions focusing on Alternative Technologies, Alternative Solvents, Recovery/Recycling, Low VOC Materials and Treatment for Environmentally Safe Disposal. The 35 invited papers presented covered a wide range of solvent substitution activities including: hardware and weapons production and maintenance, paint stripping, coating applications, printed circuit boards, metal cleaning, metal finishing, manufacturing, compliance monitoring and process control monitoring. This publication includes the majority of these presentations. In addition, in order to further facilitate information exchange and technology transfer, the US Air Force and DOE solicited additional papers under a general Call for Papers.'' These papers, which underwent review and final selection by a peer review committee, are also included in this combined Proceedings/Compendium. For those involved in handling, using or managing hazardous and toxic solvents, this document should prove to be a valuable resource, providing the most up-to-date information on current technologies and practices in solvent substitution. Individual papers are abstracted separated.

  14. Solvent effect-driven assembly of W/Cu/S cluster-based coordination polymers from the cluster precursor [Et4N][Tp*WS3(CuBr)3] and CuCN: isolation, structures and enhanced NLO responses.

    PubMed

    Liu, Quan; Ren, Zhi-Gang; Deng, Li; Zhang, Wen-Hua; Zhao, Xin; Sun, Zhen-Rong; Lang, Jian-Ping

    2015-01-01

    We herein describe a coordination polymer system built upon the reactions of a W/Cu/S cluster precursor [Et4N][Tp*WS3(CuBr)3] (1, Tp* = hydridotris(3,5-dimethylpyrazol-1-yl)borate) with three equivalents of CuCN through solvent modulation. Four coordination polymers, namely, [Tp*WS3Cu3(μ3-DMF)(CN)3Cu(Py)] (2), [Tp*WS3Cu3(μ3-DMF)(CN)3Cu] (3), [Tp*WS3Cu3(μ3-DMF)(CN)3Cu]·4aniline (4·4aniline) and [Tp*WS3Cu3(μ3-DMF)(CN)3Cu]·2(DMF)0.5 (5·2(DMF)0.5), are isolated in different solvent systems and characterized by means of elemental analysis, FT-IR, UV-Vis, ESI-MS and single-crystal X-ray diffraction. Compounds 2-5 feature μ3-DMF association with the nest-shaped [WS3Cu3] cluster cores, yielding cubane-type [WS3Cu3O] clusters which are further linked to single Cu(I) ions through CN bridges to provide 1D or 2D structures. Compounds 3-5 have identical chemical compositions in their main fragments but with distinctively different structural features, and are therefore topological isomers. Compound 2 has a ladder-type structure in which the side rails contain alternately linked cluster cores and Cu(I) ions. Compound 3 has a 2D (6,3) network with alternately arranged cluster cores and Cu(I) ions. Both 4 and 5 have 2D structures with 4·8(2) topology. In 4, a pair of cluster cores and Cu(I) ions form a 4-membered ring which is further linked to four equivalent rings through four CN ligands via a cluster core-to-Cu arrangement; while in the structure of 5, the same 4-membered rings as those in 4 are extended to equivalent rings via a cluster core-to-cluster and Cu-to-Cu arrangement. The hyperpolarizabilities (γ) of the polymeric networks exhibit an enhancement of more than 10 times compared to their parent cluster, 1. PMID:25353691

  15. Solvent substitutes

    SciTech Connect

    Evanoff, S.P.

    1995-09-01

    The environmental and industrial hygiene regulations promulgated since 1980, most notably the Superfund Amendments and Reauthorization Act (SARA), the Hazardous and Solid Waste Amendments to the Resources Conservation and Recovery Act (RCRA), and the Clean Air Act Amendments of 1990, have brought about an increased emphasis on user exposure, hazardous waste generation, and air emissions. As a result, industry is performing a fundamental reassessment of cleaning solvents, processes, and procedures. The more progressive organizations have made their goal the elimination of solvents that may pose significant potential human health and environmental hazards. This chapter discusses solvent cleaning in metal-finishing, metal-manufacturing, and industrial maintenance applications; precision cleaning; and electronics manufacturing. Nonmetallic cleaning, adhesives, coatings, inks, and aerosols also will be addressed, but in a more cursory manner.

  16. Weak Interactions

    DOE R&D Accomplishments Database

    Lee, T. D.

    1957-06-01

    Experimental results on the non-conservation of parity and charge conservation in weak interactions are reviewed. The two-component theory of the neutrino is discussed. Lepton reactions are examined under the assumption of the law of conservation of leptons and that the neutrino is described by a two- component theory. From the results of this examination, the universal Fermi interactions are analyzed. Although reactions involving the neutrino can be described, the same is not true of reactions which do not involve the lepton, as the discussion of the decay of K mesons and hyperons shows. The question of the invariance of time reversal is next examined. (J.S.R.)

  17. Controlling the framework formation of silver(I) coordination polymers with 1,4-bis(phenylthio)butane by varying the solvents, metal-to-ligand ratio, and counteranions.

    PubMed

    Bu, Xian-He; Chen, Wei; Hou, Wen-Feng; Du, Miao; Zhang, Ruo-Hua; Brisse, Francois

    2002-07-01

    The reactions of 1,4-bis(phenylthio)butane (L) with Ag(I) salts in varied conditions (varying the solvents, metal-to-ligand ratios, and counteranions) lead to the formation of four new two-dimensional (2D) coordination polymers with different network structures: [Ag(2)L(3)(ClO(4))(2)](infinity) 1, [Ag(2)L(3)(ClO(4))(2) x CH(3)OH](infinity) 2, [[AgL(2)](ClO(4))](infinity) 3, and [AgLNO(3)](infinity) 4. All the structures were established by single-crystal X-ray diffraction analysis. Crystal data for 1: triclinic, P-1, a = 11.0253(9) A, b = 11.3455(9) A, c = 11.5231(9) A, alpha = 93.931(2) degrees, beta = 92.689(2) degrees, gamma = 112.9810(10) degrees, Z = 2. 2: triclinic, P-1, a = 11.9147(13) A, b = 16.1534(17) A, c = 16.2259(17) A, alpha = 74.977(2) degrees, beta = 69.030(2) degrees, gamma = 69.986(2) degrees, Z = 2. 3: triclinic, P-1, a = 12.1617(9) A, b = 12.5054(10) A, c = 13.1547(10) A, alpha = 64.3370(10) degrees, beta =85.938 (2) degrees, gamma = 69.3010(10) degrees, Z = 2. 4: monoclinic, P2(1)/c, a = 5.4032(17) A, b = 16.974(6) A, c = 19.489(6) A, beta = 94.234(6) degrees, Z = 4. In all four complexes, each Ag(I) center has a tetracoordination geometry, and the 2D networks consist of fused large macrometallacyclic ring systems. The "hexagonal" 42-membered rings, Ag(6)L(6), observed in 1 and 2 are nearly identical, which could be considered as unique examples of self-sustaining noninterpenetrated frameworks formed with flexible ligands. The repeating rectangular 28-membered macrometallacycle, Ag(4)L(4), is the basis for the network of 3, in which the perchlorate anions occupy the voids to prevent the ring from collapsing. In 4, columns of the fused rectangular 22-membered rings, Ag(4)L(2)(NO(3))(2), are cross-linked through the L ligands to form a unique 2D network consisting of two types of 22-membered repeating units.

  18. Underwater contact adhesion and microarchitecture in polyelectrolyte complexes actuated by solvent exchange

    NASA Astrophysics Data System (ADS)

    Zhao, Qiang; Lee, Dong Woog; Ahn, B. Kollbe; Seo, Sungbaek; Kaufman, Yair; Israelachvili, Jacob N.; Waite, J. Herbert

    2016-04-01

    Polyelectrolyte complexation is critical to the formation and properties of many biological and polymeric materials, and is typically initiated by aqueous mixing followed by fluid-fluid phase separation, such as coacervation. Yet little to nothing is known about how coacervates evolve into intricate solid microarchitectures. Inspired by the chemical features of the cement proteins of the sandcastle worm, here we report a versatile and strong wet-contact microporous adhesive resulting from polyelectrolyte complexation triggered by solvent exchange. After premixing a catechol-functionalized weak polyanion with a polycation in dimethyl sulphoxide (DMSO), the solution was applied underwater to various substrates whereupon electrostatic complexation, phase inversion, and rapid setting were simultaneously actuated by water-DMSO solvent exchange. Spatial and temporal coordination of complexation, inversion and setting fostered rapid (~25 s) and robust underwater contact adhesion (Wad >= 2 J m-2) of complexed catecholic polyelectrolytes to all tested surfaces including plastics, glasses, metals and biological materials.

  19. Solvent wash solution

    DOEpatents

    Neace, James C.

    1986-01-01

    Process for removing diluent degradation products from a solvent extraction solution, which has been used to recover uranium and plutonium from spent nuclear fuel. A wash solution and the solvent extraction solution are combined. The wash solution contains (a) water and (b) up to about, and including, 50 volume percent of at least one-polar water-miscible organic solvent based on the total volume of the water and the highly-polar organic solvent. The wash solution also preferably contains at least one inorganic salt. The diluent degradation products dissolve in the highly-polar organic solvent and the organic solvent extraction solvent do not dissolve in the highly-polar organic solvent. The highly-polar organic solvent and the extraction solvent are separated.

  20. Solvent wash solution

    DOEpatents

    Neace, J.C.

    1984-03-13

    A process is claimed for removing diluent degradation products from a solvent extraction solution, which has been used to recover uranium and plutonium from spent nuclear fuel. A wash solution and the solvent extraction solution are combined. The wash solution contains (a) water and (b) up to about, and including, 50 vol % of at least one-polar water-miscible organic solvent based on the total volume of the water and the highly-polar organic solvent. The wash solution also preferably contains at least one inorganic salt. The diluent degradation products dissolve in the highly-polar organic solvent and the organic solvent extraction solvent do not dissolve in the highly-polar organic solvent. The highly-polar organic solvent and the extraction solvent are separated.

  1. The role of solvent and the outer coordination sphere on H2 oxidation using [Ni(PCy2NPyz2)2]2+

    SciTech Connect

    Dutta, Arnab; Lense, Sheri J.; Roberts, John A.; Helm, Monte L.; Shaw, Wendy J.

    2015-05-01

    Hydrogenase enzymes are reversible catalysts for H2 production/oxidation, operating with fast rates and minimal overpotentials in water. Many synthetic catalyst mimics of hydrogenase operate in organic solvents. However, recent work has demonstrated the importance of water in the performance of some model complexes. In this work, the H2oxidation activity of [Ni(PCy2N(3–pyridazyl)methyl2)2]2+ (CyPyz) was compared as a function of acetonitrile, methanol, and water. The reactivity was compared under neutral and acidic conditions in all three solvents and improvement in catalytic activity, from 2 to 40 s-1, was observed with increasing hydrogen bonding ability of the solvent. In addition, the overpotential for catalysis drops significantly in the presence of acid in all solvents, from as high as 600 mV to as low as 70 mV, primarily due to the shift in the equilibrium potential under these conditions. Finally, H2 production was also observed in the same solution, demonstrating bidirectional (irreversible) homogeneous H2 production/oxidation. A structurally and electronically similar complex with a benzyl instead of a pyridazyl group was not stable under these conditions, limiting the evaluation of the contributions of the outer coordination sphere. Collectively, we show that by tuning conditions we can promote fast, efficient H2 oxidation and bidirectional catalysis.

  2. Weak Energy: Form and Function

    NASA Astrophysics Data System (ADS)

    Parks, Allen D.

    The equation of motion for a time-dependent weak value of a quantum mechanical observable contains a complex valued energy factor—the weak energy of evolution. This quantity is defined by the dynamics of the pre-selected and post-selected states which specify the observable's weak value. It is shown that this energy: (i) is manifested as dynamical and geometric phases that govern the evolution of the weak value during the measurement process; (ii) satisfies the Euler-Lagrange equations when expressed in terms of Pancharatnam (P) phase and Fubini-Study (FS) metric distance; (iii) provides for a PFS stationary action principle for quantum state evolution; (iv) time translates correlation amplitudes; (v) generalizes the temporal persistence of state normalization; and (vi) obeys a time-energy uncertainty relation. A similar complex valued quantity—the pointed weak energy of an evolving quantum state—is also defined and several of its properties in PFS coordinates are discussed. It is shown that the imaginary part of the pointed weak energy governs the state's survival probability and its real part is—to within a sign—the Mukunda-Simon geometric phase for arbitrary evolutions or the Aharonov-Anandan (AA) geometric phase for cyclic evolutions. Pointed weak energy gauge transformations and the PFS 1-form are defined and discussed and the relationship between the PFS 1-form and the AA connection 1-form is established. [Editors note: for a video of the talk given by Prof. Parks at the Aharonov-80 conference in 2012 at Chapman University, see http://quantum.chapman.edu/talk-25.

  3. A computational study of ultrafast acid dissociation and acid-base neutralization reactions. II. The relationship between the coordination state of solvent molecules and concerted versus sequential acid dissociation.

    PubMed

    Maurer, Patrick; Thomas, Vibin; Iftimie, Radu

    2011-03-01

    We investigate the role played by the coordination state of pre-existing water wires during the dissociation of moderately strong acids by means of first-principles molecular dynamics calculations. By preparing 2,4,6-tricyanophenol (calc. pKa∼0.5) in two different initial states, we are able to observe sequential as well as concerted trajectories of dissociation: On one hand, equilibrium dissociation takes place on a ∼50 ps timescale; proton conduction occurs through three-coordinated water wires in this case, by means of sequential Grotthus hopping. On the other hand, by preparing 2,4,6-tricyanophenol in a hydration state inherited from that of equilibrated phenol (calc. pKa=7.6), the moderately strong acid finds itself in a presolvated state from which dissociation can take place on a ∼1 ps timescale. In this case, concerted dissociation trajectories are observed, which consist of proton translocation through two intervening, four-coordinated, water molecules in 0.1-1.0 ps. The present results suggest that, in general, the mechanism of proton translocation depends on how the excess proton is injected into a hydrogen bond network. In particular, if the initial conditions favour proton release to a fourfold H-bonded water molecule, proton translocation by as much as 6-8 Å can take place on a sub-picosecond timescale.

  4. A computational study of ultrafast acid dissociation and acid-base neutralization reactions. II. The relationship between the coordination state of solvent molecules and concerted versus sequential acid dissociation

    NASA Astrophysics Data System (ADS)

    Maurer, Patrick; Thomas, Vibin; Iftimie, Radu

    2011-03-01

    We investigate the role played by the coordination state of pre-existing water wires during the dissociation of moderately strong acids by means of first-principles molecular dynamics calculations. By preparing 2,4,6-tricyanophenol (calc. pKa˜0.5) in two different initial states, we are able to observe sequential as well as concerted trajectories of dissociation: On one hand, equilibrium dissociation takes place on a ˜50 ps timescale; proton conduction occurs through three-coordinated water wires in this case, by means of sequential Grotthus hopping. On the other hand, by preparing 2,4,6-tricyanophenol in a hydration state inherited from that of equilibrated phenol (calc. pKa = 7.6), the moderately strong acid finds itself in a presolvated state from which dissociation can take place on a ˜1 ps timescale. In this case, concerted dissociation trajectories are observed, which consist of proton translocation through two intervening, four-coordinated, water molecules in 0.1-1.0 ps. The present results suggest that, in general, the mechanism of proton translocation depends on how the excess proton is injected into a hydrogen bond network. In particular, if the initial conditions favour proton release to a fourfold H-bonded water molecule, proton translocation by as much as 6-8 Å can take place on a sub-picosecond timescale.

  5. NEPTUNIUM SOLVENT EXTRACTION PROCESS

    DOEpatents

    Dawson, L.R.; Fields, P.R.

    1959-10-01

    The separation of neptunium from an aqueous solution by solvent extraction and the extraction of neptunium from the solvent solution are described. Neptunium is separated from an aqueous solution containing tetravalent or hexavalent neptunium nitrate, nitric acid, and a nitrate salting out agent, such as sodium nitrate, by contacting the solution with an organic solvent such as diethyl ether. Subsequently, the neptunium nitrate is extracted from the organic solvent extract phase with water.

  6. Solvents safety handbook

    SciTech Connect

    De Renzo, D.J.

    1986-01-01

    Know solvents and how to protect yourself from dangerous exposure to them. Instant information for decision-making regarding industrial solvents in everyday use, is provided in this handbook which is a compilation of data on 335 hazardous and frequently-used solvents.

  7. Weak scale supersymmetry

    SciTech Connect

    Hall, L.J. California Univ., Berkeley, CA . Dept. of Physics)

    1990-11-12

    An introduction to the ideas and current state of weak scale supersymmetry is given. It is shown that LEP data on Z decays has already excluded two of the most elegant models of weak scale supersymmetry. 14 refs.

  8. Solvents and sustainable chemistry

    PubMed Central

    Welton, Tom

    2015-01-01

    Solvents are widely recognized to be of great environmental concern. The reduction of their use is one of the most important aims of green chemistry. In addition to this, the appropriate selection of solvent for a process can greatly improve the sustainability of a chemical production process. There has also been extensive research into the application of so-called green solvents, such as ionic liquids and supercritical fluids. However, most examples of solvent technologies that give improved sustainability come from the application of well-established solvents. It is also apparent that the successful implementation of environmentally sustainable processes must be accompanied by improvements in commercial performance. PMID:26730217

  9. Solvent recycle/recovery

    SciTech Connect

    Paffhausen, M.W.; Smith, D.L.; Ugaki, S.N.

    1990-09-01

    This report describes Phase I of the Solvent Recycle/Recovery Task of the DOE Chlorinated Solvent Substitution Program for the US Air Force by the Idaho National Engineering Laboratory, EG G Idaho, Inc., through the US Department of Energy, Idaho Operations Office. The purpose of the task is to identify and test recovery and recycling technologies for proposed substitution solvents identified by the Biodegradable Solvent Substitution Program and the Alternative Solvents/Technologies for Paint Stripping Program with the overall objective of minimizing hazardous wastes. A literature search to identify recycle/recovery technologies and initial distillation studies has been conducted. 4 refs.

  10. Insights into water coordination associated with the Cu(II)/Cu(I) electron transfer at a biomimetic Cu centre.

    PubMed

    Porras Gutiérrez, Ana Gabriela; Zeitouny, Joceline; Gomila, Antoine; Douziech, Bénédicte; Cosquer, Nathalie; Conan, Françoise; Reinaud, Olivia; Hapiot, Philippe; Le Mest, Yves; Lagrost, Corinne; Le Poul, Nicolas

    2014-05-01

    The coordination properties of the biomimetic complex [Cu(TMPA)(H2O)](CF3SO3)2 (TMPA = tris(2-pyridylmethyl)amine) have been investigated by electrochemistry combined with UV-Vis and EPR spectroscopy in different non-coordinating media including imidazolium-based room-temperature ionic liquids, for different water contents. The solid-state X-ray diffraction analysis of the complex shows that the cupric centre lies in a N4O coordination environment with a nearly perfect trigonal bipyramidal geometry (TBP), the water ligand being axially coordinated to Cu(II). In solution, the coordination geometry of the complex remains TBP in all media. Neither the triflate ion nor the anions of the ionic liquids were found to coordinate the copper centre. Cyclic voltammetry in all media shows that the decoordination of the water molecule occurs upon monoelectronic reduction of the Cu(II) complex. Back-coordination of the water ligand at the cuprous state can be detected by increasing the water content and/or decreasing the timescale of the experiment. Numerical simulations of the voltammograms allow the determination of kinetics and thermodynamics for the water association-dissociation mechanism. The resulting data suggest that (i) the binding/unbinding of water at the Cu(I) redox state is relatively slow and equilibrated in all media, and (ii) the binding of water at Cu(I) is somewhat faster in the ionic liquids than in the non-coordinating solvents, while the decoordination process is weakly sensitive to the nature of the solvents. These results suggest that ionic liquids favour water exchange without interfering with the coordination sphere of the metal centre. This makes them promising media for studying host-guest reactions with biomimetic complexes.

  11. Technology coordination

    NASA Technical Reports Server (NTRS)

    Hartman, Steven

    1992-01-01

    Viewgraphs on technology coordination are provided. Topics covered include: technology coordination process to date; goals; how the Office of Aeronautics and Space Technology (OAST) can support the Office of Space Science and Applications (OSSA); how OSSA can support OAST; steps to technology transfer; and recommendations.

  12. Deep eutectic solvents as novel extraction media for phenolic compounds from model oil.

    PubMed

    Gu, Tongnian; Zhang, Mingliang; Tan, Ting; Chen, Jia; Li, Zhan; Zhang, Qinghua; Qiu, Hongdeng

    2014-10-11

    Deep eutectic solvents (DES) as a new kind of green solvent were used for the first time to excellently extract phenolic compounds from model oil. It was also proved that DES could be used to extract other polar compounds from non-polar or weakly-polar solvents by liquid-phase microextraction.

  13. Deep eutectic solvents as novel extraction media for phenolic compounds from model oil.

    PubMed

    Gu, Tongnian; Zhang, Mingliang; Tan, Ting; Chen, Jia; Li, Zhan; Zhang, Qinghua; Qiu, Hongdeng

    2014-10-11

    Deep eutectic solvents (DES) as a new kind of green solvent were used for the first time to excellently extract phenolic compounds from model oil. It was also proved that DES could be used to extract other polar compounds from non-polar or weakly-polar solvents by liquid-phase microextraction. PMID:25144155

  14. Postselected weak measurement beyond the weak value

    SciTech Connect

    Geszti, Tamas

    2010-04-15

    Closed expressions are derived for the quantum measurement statistics of pre- and postselected Gaussian particle beams. The weakness of the preselection step is shown to compete with the nonorthogonality of postselection in a transparent way. The approach is shown to be useful in analyzing postselection-based signal amplification, allowing measurements to be extended far beyond the range of validity of the well-known Aharonov-Albert-Vaidman limit. Additionally, the present treatment connects postselected weak measurement to the topic of phase-contrast microscopy.

  15. Poisson Coordinates.

    PubMed

    Li, Xian-Ying; Hu, Shi-Min

    2013-02-01

    Harmonic functions are the critical points of a Dirichlet energy functional, the linear projections of conformal maps. They play an important role in computer graphics, particularly for gradient-domain image processing and shape-preserving geometric computation. We propose Poisson coordinates, a novel transfinite interpolation scheme based on the Poisson integral formula, as a rapid way to estimate a harmonic function on a certain domain with desired boundary values. Poisson coordinates are an extension of the Mean Value coordinates (MVCs) which inherit their linear precision, smoothness, and kernel positivity. We give explicit formulas for Poisson coordinates in both continuous and 2D discrete forms. Superior to MVCs, Poisson coordinates are proved to be pseudoharmonic (i.e., they reproduce harmonic functions on n-dimensional balls). Our experimental results show that Poisson coordinates have lower Dirichlet energies than MVCs on a number of typical 2D domains (particularly convex domains). As well as presenting a formula, our approach provides useful insights for further studies on coordinates-based interpolation and fast estimation of harmonic functions.

  16. Aperiodic Weak Topological Superconductors

    NASA Astrophysics Data System (ADS)

    Fulga, I. C.; Pikulin, D. I.; Loring, T. A.

    2016-06-01

    Weak topological phases are usually described in terms of protection by the lattice translation symmetry. Their characterization explicitly relies on periodicity since weak invariants are expressed in terms of the momentum-space torus. We prove the compatibility of weak topological superconductors with aperiodic systems, such as quasicrystals. We go beyond usual descriptions of weak topological phases and introduce a novel, real-space formulation of the weak invariant, based on the Clifford pseudospectrum. A nontrivial value of this index implies a nontrivial bulk phase, which is robust against disorder and hosts localized zero-energy modes at the edge. Our recipe for determining the weak invariant is directly applicable to any finite-sized system, including disordered lattice models. This direct method enables a quantitative analysis of the level of disorder the topological protection can withstand.

  17. Aperiodic Weak Topological Superconductors.

    PubMed

    Fulga, I C; Pikulin, D I; Loring, T A

    2016-06-24

    Weak topological phases are usually described in terms of protection by the lattice translation symmetry. Their characterization explicitly relies on periodicity since weak invariants are expressed in terms of the momentum-space torus. We prove the compatibility of weak topological superconductors with aperiodic systems, such as quasicrystals. We go beyond usual descriptions of weak topological phases and introduce a novel, real-space formulation of the weak invariant, based on the Clifford pseudospectrum. A nontrivial value of this index implies a nontrivial bulk phase, which is robust against disorder and hosts localized zero-energy modes at the edge. Our recipe for determining the weak invariant is directly applicable to any finite-sized system, including disordered lattice models. This direct method enables a quantitative analysis of the level of disorder the topological protection can withstand. PMID:27391744

  18. Two-Coordinate Magnesium(I) Dimers Stabilized by Super Bulky Amido Ligands.

    PubMed

    Boutland, Aaron J; Dange, Deepak; Stasch, Andreas; Maron, Laurent; Jones, Cameron

    2016-08-01

    A variety of very bulky amido magnesium iodide complexes, LMgI(solvent)0/1 and [LMg(μ-I)(solvent)0/1 ]2 (L=-N(Ar)(SiR3 ); Ar=C6 H2 {C(H)Ph2 }2 R'-2,6,4; R=Me, Pr(i) , Ph, or OBu(t) ; R'=Pr(i) or Me) have been prepared by three synthetic routes. Structurally characterized examples of these materials include the first unsolvated amido magnesium halide complexes, such as [LMg(μ-I)]2 (R=Me, R'=Pr(i) ). Reductions of several such complexes with KC8 in the absence of coordinating solvents have afforded the first two-coordinate magnesium(I) dimers, LMg-MgL (R=Me, Pr(i) or Ph; R'=Pr(i) , or Me), in low to good yields. Reductions of two of the precursor complexes in the presence of THF have given the related THF adduct complexes, L(THF)Mg-Mg(THF)L (R=Me; R'=Pr(i) ) and LMg-Mg(THF)L (R=Pr(i) ; R'=Me) in trace yields. The X-ray crystal structures of all magnesium(I) complexes were obtained. DFT calculations on the unsolvated examples reveal their Mg-Mg bonds to be covalent and of high s-character, while Ph⋅⋅⋅Mg bonding interactions in the compounds were found to be weak at best. PMID:27303934

  19. The Lanthanide Contraction beyond Coordination Chemistry.

    PubMed

    Ferru, Geoffroy; Reinhart, Benjamin; Bera, Mrinal K; Olvera de la Cruz, Monica; Qiao, Baofu; Ellis, Ross J

    2016-05-10

    The lanthanide contraction is conceptualized traditionally through coordination chemistry. Here we break this mold in a structural study of lanthanide ions dissolved in an amphiphilic liquid. The lanthanide contraction perturbs the weak interactions between molecular aggregates that drive mesoscale assembly and emergent behavior. The weak interactions correlate with lanthanide ion transport properties, suggesting new strategies for rare-earth separation that exploit forces outside of the coordination sphere.

  20. Solvent-free synthesis

    EPA Science Inventory

    This chapter gives a brief introduction about solvent-free reactions whose importance can be gauged by the increasing number of publications every year during the last decade. The mechanistic aspects of the reactions under solvent-free conditions have been highlighted. Our observ...

  1. SOLVENT EXTRACTION OF NEPTUNIUM

    DOEpatents

    Butler, J.P.

    1958-08-12

    A process is described for the recovery of neptuniunn from dissolver solutions by solvent extraction. The neptunium containing solution should be about 5N, in nitric acid.and about 0.1 M in ferrous ion. The organic extracting agent is tributyl phosphate, and the neptuniunn is recovered from the organic solvent phase by washing with water.

  2. Alternative Green Solvents Project

    NASA Technical Reports Server (NTRS)

    Maloney, Phillip R.

    2012-01-01

    Necessary for safe and proper functioning of equipment. Mainly halogenated solvents. Tetrachloride, Trichloroethylene (TCE), CFC-113. No longer used due to regulatory/safety concerns. Precision Cleaning at KSC: Small % of total parts. Used for liquid oxygen (LOX) systems. Dual solvent process. Vertrel MCA (decafluoropentane (DFP) and trons-dichloroethylene) HFE-7100. DFP has long term environmental concerns. Project Goals: a) Identify potential replacements. b) 22 wet chemical processes. c) 3 alternative processes. d) Develop test procedures. e) Contamination and cleaning. f) Analysis. g) Use results to recommend alternative processes. Conclusions: a) No alternative matched Vertrel in this study. b) No clear second place solvent. c) Hydrocarbons- easy; Fluorinated greases- difficult. d) Fluorinated component may be needed in replacement solvent. e) Process may need to make up for shortcoming of the solvent. f) Plasma and SCC02 warrant further testing.

  3. Isothermal calorimetric titrations on charge-assisted halogen bonds: role of entropy, counterions, solvent, and temperature.

    PubMed

    Walter, Sebastian M; Kniep, Florian; Rout, Laxmidhar; Schmidtchen, Franz P; Herdtweck, Eberhardt; Huber, Stefan M

    2012-05-23

    We have conducted isothermal calorimetric titrations to investigate the halogen-bond strength of cationic bidentate halogen-bond donors toward halides, using bis(iodoimidazolium) compounds as probes. These data are intended to aid the rational design of halogen-bond donors as well as the development of halogen-bond-based applications in solution. In all cases examined, the entropic contribution to the overall free energy of binding was found to be very important. The binding affinities showed little dependency on the weakly coordinating counteranions of the halogen-bond donors but became slightly stronger with higher temperatures. We also found a marked influence of different solvents on the interaction strength. The highest binding constant detected in this study was 3.3 × 10(6) M(-1).

  4. Conformational transitions of a weak polyampholyte

    NASA Astrophysics Data System (ADS)

    Narayanan Nair, Arun Kumar; Uyaver, Sahin; Sun, Shuyu

    2014-10-01

    Using grand canonical Monte Carlo simulations of a flexible polyelectrolyte where the charges are in contact with a reservoir of constant chemical potential given by the solution pH, we study the behavior of weak polyelectrolytes in poor and good solvent conditions for polymer backbone. We address the titration behavior and conformational properties of a flexible diblock polyampholyte chain formed of two oppositely charged weak polyelectrolyte blocks, each containing equal number of identical monomers. The change of solution pH induces charge asymmetry in a diblock polyampholyte. For diblock polyampholyte chains in poor solvents, we demonstrate that a discontinuous transition between extended (tadpole) and collapsed (globular) conformational states is attainable by varying the solution pH. The double-minima structure in the probability distribution of the free energy provides direct evidence for the first-order like nature of this transition. At the isoelectric point electrostatically driven coil-globule transition of diblock polyampholytes in good solvents is found to consist of different regimes identified with increasing electrostatic interaction strength. At pH values above or below the isoelectric point diblock chains are found to have polyelectrolyte-like behavior due to repulsion between uncompensated charges along the chain.

  5. Weak measure expansive flows

    NASA Astrophysics Data System (ADS)

    Lee, Keonhee; Oh, Jumi

    2016-01-01

    A notion of measure expansivity for flows was introduced by Carrasco-Olivera and Morales in [3] as a generalization of expansivity, and they proved that there were no measure expansive flows on closed surfaces. In this paper we introduce a concept of weak measure expansivity for flows which is really weaker than that of measure expansivity, and show that there is a weak measure expansive flow on a closed surface. Moreover we show that any C1 stably weak measure expansive flow on a C∞ closed manifold M is Ω-stable, and any C1 stably measure expansive flow on M satisfies both Axiom A and the quasi-transversality condition.

  6. SOLVENT EXTRACTION PROCESS

    DOEpatents

    Jonke, A.A.

    1957-10-01

    In improved solvent extraction process is described for the extraction of metal values from highly dilute aqueous solutions. The process comprises contacting an aqueous solution with an organic substantially water-immiscible solvent, whereby metal values are taken up by a solvent extract phase; scrubbing the solvent extract phase with an aqueous scrubbing solution; separating an aqueous solution from the scrubbed solvent extract phase; and contacting the scrubbed solvent phase with an aqueous medium whereby the extracted metal values are removed from the solvent phase and taken up by said medium to form a strip solution containing said metal values, the aqueous scrubbing solution being a mixture of strip solution and an aqueous solution which contains mineral acids anions and is free of the metal values. The process is particularly effective for purifying uranium, where one starts with impure aqueous uranyl nitrate, extracts with tributyl phosphate dissolved in carbon tetrachloride, scrubs with aqueous nitric acid and employs water to strip the uranium from the scrubbed organic phase.

  7. COORDINATED AV.

    ERIC Educational Resources Information Center

    CLEAVES, PAUL C.; AND OTHERS

    THE INSTRUCTIONAL MATERIALS CENTER IS LOCATED IN THE LOCAL HIGH SCHOOL AND SUPPLIES ALL SCHOOLS IN THE AREA. AUDIOVISUAL EQUIPMENT ORDERS, AFTER SELECTIONS ARE MADE BY THE CLASSROOM TEACHER, ARE PROCESSED BY THE CENTER, CONFIRMED AND DELIVERED BY TRUCK THREE TIMES EACH WEEK. EACH SCHOOL HAS A BUILDING COORDINATOR WHO CHECKS THE ORDERS INTO THE…

  8. Solvent alternatives guide

    SciTech Connect

    Elion, J.M.; Monroe, K.R.; Hill, E.A.

    1996-06-01

    It is no longer legal to manufacture or import chlorofluorocarbon 113 or methyl chloroform solvents, and companies that currently clean their parts with either material are now required to implement environmentally safe substitutes. To help find alternative methods, Research Triangle Institute`s Surface Cleaning Technology Program has designed a Solvent Alternatives Guide (SAGE), an online tool that enables access to practical information and recommendations for acceptable solvents. Developed in partnership with the US Environmental Protection Agency, SAGE is available free of charge on the Internet`s World Wide Web.

  9. History of Weak Interactions

    DOE R&D Accomplishments Database

    Lee, T. D.

    1970-07-01

    While the phenomenon of beta-decay was discovered near the end of the last century, the notion that the weak interaction forms a separate field of physical forces evolved rather gradually. This became clear only after the experimental discoveries of other weak reactions such as muon-decay, muon-capture, etc., and the theoretical observation that all these reactions can be described by approximately the same coupling constant, thus giving rise to the notion of a universal weak interaction. Only then did one slowly recognize that the weak interaction force forms an independent field, perhaps on the same footing as the gravitational force, the electromagnetic force, and the strong nuclear and sub-nuclear forces.

  10. Neutron Polarization Analysis for Biphasic Solvent Extraction Systems

    DOE PAGES

    Motokawa, Ryuhei; Endo, Hitoshi; Nagao, Michihiro; Heller, William T.

    2016-06-16

    Here we performed neutron polarization analysis (NPA) of extracted organic phases containing complexes, comprised of Zr(NO3)4 and tri-n-butyl phosphate, which enabled decomposition of the intensity distribution of small-angle neutron scattering (SANS) into the coherent and incoherent scattering components. The coherent scattering intensity, containing structural information, and the incoherent scattering compete over a wide range of magnitude of scattering vector, q, specifically when q is larger than q* ≈ 1/Rg, where Rg is the radius of gyration of scatterer. Therefore, it is important to determine the incoherent scattering intensity exactly to perform an accurate structural analysis from SANS data when Rgmore » is small, such as the aforementioned extracted coordination species. Although NPA is the best method for evaluating the incoherent scattering component for accurately determining the coherent scattering in SANS, this method is not used frequently in SANS data analysis because it is technically challenging. In this study, we successfully demonstrated that experimental determination of the incoherent scattering using NPA is suitable for sample systems containing a small scatterer with a weak coherent scattering intensity, such as extracted complexes in biphasic solvent extraction systems.« less

  11. CHLORINATED SOLVENT PLUME CONTROL

    EPA Science Inventory

    This lecture will cover recent success in controlling and assessing the treatment of shallow ground water plumes of chlorinated solvents, other halogenated organic compounds, and methyl tert-butyl ether (MTBE).

  12. SOLVENT WASTE REDUCTION ALTERNATIVES

    EPA Science Inventory

    This publication contains edited versions of presentations on this subject made at five Technology Transfer seminars in 1988. Chapters are included on land disposal regulations and requirements; waste solvent disposal alternatives from various industries such as process equipment...

  13. Continuous countercurrent membrane column for the separation of solute/solvent and solvent/solvent systems

    DOEpatents

    Nerad, Bruce A.; Krantz, William B.

    1988-01-01

    A reverse osmosis membrane process or hybrid membrane - complementary separator process for producing enriched product or waste streams from concentrated and dilute feed streams for both solvent/solvent and solute/solvent systems is described.

  14. Supercritical solvent coal extraction

    NASA Technical Reports Server (NTRS)

    Compton, L. E. (Inventor)

    1984-01-01

    Yields of soluble organic extract are increased up to about 50% by the supercritical extraction of particulate coal at a temperature below the polymerization temperature for coal extract fragments (450 C.) and a pressure from 500 psig to 5,000 psig by the conjoint use of a solvent mixture containing a low volatility, high critical temperature coal dissolution catalyst such as phenanthrene and a high volatility, low critical temperature solvent such as toluene.

  15. SOLVENT EXTRACTION OF RUTHENIUM

    DOEpatents

    Hyman, H.H.; Leader, G.R.

    1959-07-14

    The separation of rathenium from aqueous solutions by solvent extraction is described. According to the invention, a nitrite selected from the group consisting of alkali nitrite and alkaline earth nitrite in an equimolecular quantity with regard to the quantity of rathenium present is added to an aqueous solution containing ruthenium tetrantrate to form a ruthenium complex. Adding an organic solvent such as ethyl ether to the resulting mixture selectively extracts the rathenium complex.

  16. Cleaning without chlorinated solvents

    SciTech Connect

    Thompson, L.M.; Simandl, R.F.

    1994-12-31

    Because of health and environmental concerns, many regulations have been passed in recent years regarding the use of chlorinated solvents. The Oak Ridge Y-12 Plant has had an active program to find alternatives for these solvents used in cleaning applications for the past 7 years. During this time frame, the quantity of solvents purchased has been reduced by 92%. The program has been a twofold effort. Vapor degreasers used in batch cleaning-operations have been replaced by ultrasonic cleaning with aqueous detergent, and other organic solvents have been identified for use in hand-wiping or specialty operations. In order to qualify these alternatives for use, experimentation was conducted on cleaning ability as well as effects on subsequent operations such as welding, painting and bonding. Cleaning ability was determined using techniques such as X-ray photoelectron spectroscopy (XPS) and Fourier Transform Infrared Spectroscopy (FTIR) which are capable of examining monolayer levels of contamination on a surface. Solvents have been identified for removal of rust preventative oils, lapping oils, machining coolants, lubricants, greases, and mold releases. Solvents have also been evaluated for cleaning urethane foam spray guns, swelling of urethanes and swelling of epoxies.

  17. Cleaning without chlorinated solvents

    NASA Technical Reports Server (NTRS)

    Thompson, L. M.; Simandl, R. F.

    1995-01-01

    Because of health and environmental concerns, many regulations have been passed in recent years regarding the use of chlorinated solvents. The Oak Ridge Y-12 Plant has had an active program to find alternatives for these solvents used in cleaning applications for the past 7 years. During this time frame, the quantity of solvents purchased has been reduced by 92 percent. The program has been a twofold effort. Vapor degreasers used in batch cleaning operations have been replaced by ultrasonic cleaning with aqueous detergent, and other organic solvents have been identified for use in hand-wiping or specialty operations. In order to qualify these alternatives for use, experimentation was conducted on cleaning ability as well as effects on subsequent operations such as welding, painting, and bonding. Cleaning ability was determined using techniques such as x-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) which are capable of examining monolayer levels of contamination on a surface. Solvents have been identified for removal of rust preventative oils, lapping oils, machining coolants, lubricants, greases, and mold releases. Solvents have also been evaluated for cleaning urethane foam spray guns, swelling of urethanes, and swelling of epoxies.

  18. Neurotoxicity of solvents.

    PubMed

    Sainio, Markku Alarik

    2015-01-01

    Worldwide, several hundred million tons of organic solvents are used annually in household, industry, and other occupational settings. Millions of workers are regularly exposed to organic solvents considered neurotoxic. Acute neurotoxicity due to high exposure of solvent is usually evident, but the nature of long-term effects, such as chronic solvent encephalopathy (CSE), has raised uncertainty even among experts. Earlier studies were criticized for their methodology, mainly epidemiologic studies or investigations of exposed groups with many possible confounders and inadequate exposure assessment. However, an increasing number of studies have been performed since, also on workers with defined CSE based on differential diagnostics. During the last decade, evidence has emerged to enable identification of CSE, a necessity for the early recognition and prevention of progression of dysfunction and disability. Selected chemicals are presented here due to their widespread use, neurotoxic potential, and ability to cause solvent encephalopathy. Constant introduction of new chemicals may introduce new hazardous chemicals or known chemicals may reveal new health effects. It is important to keep an open mind for new findings of solvent-related neurobehavioral effects. PMID:26563785

  19. LLNL solvent substitution

    SciTech Connect

    Benkovitch, M.G.

    1992-12-01

    Allied-Signal Inc., Kansas City Division (KCD), manufactures the electrical, electromechanical, mechanical, and plastic components for nuclear weapons. The KCD has made a commitment to eliminate the use of chlorohydrocarbon (CHC) and chlorofluorocarbon (CFC) solvents to the greatest technical extent possible consistent with nuclear safety and stockpile reliability requirements by July 1993. Several non-halogenated solvents (Exxate 1000, Bioact EC-7, Bioact EC-7R, d-limonene, ACT-100, Kester 5769, and isopropyl alcohol) were evaluated to determine the most effective, non-chlorinated non-fluorinated, alternate solvent cleaning system for a particular electronic assembly in lieu of the current trichloroethylenefisopropyl alcohol baseline cleaning process. All of these solvents were evaluated using current manual spray cleaning processes. The solvents were evaluated for their effectiveness in removing a rosin based RMA solder flux, a particular silicone mold release, and a wide variety of general contaminants (oils, greases, mold releases, resins, etc.) normally found in production departments. A DI water/isopropyl alcohol spray cleaning process was also evaluated for removing two organic acid fluxes. Test samples were contaminated, spray cleaned with the appropriate solvent, and then analyzed for cleanliness. The Meseran Surface Analyzer was used to measure,, organic contamination on the samples before and after cleaning. An Omega Meter Model 600 was also used to detect solder flux residues.

  20. Dendritic brushes under theta and poor solvent conditions.

    PubMed

    Gergidis, Leonidas N; Kalogirou, Andreas; Charalambopoulos, Antonios; Vlahos, Costas

    2013-07-28

    The effects of solvent quality on the internal stratification of polymer brushes formed by dendron polymers up to third generation were studied by means of molecular dynamics simulations with Langevin thermostat. The distributions of polymer units, of the free ends, the radii of gyration, and the back folding probabilities of the dendritic spacers were studied at the macroscopic states of theta and poor solvent. For high grafting densities we observed a small decrease in the height of the brush as the solvent quality decreases. The internal stratification in theta solvent was similar to the one we found in good solvent, with two and in some cases three kinds of populations containing short dendrons with weakly extended spacers, intermediate-height dendrons, and tall dendrons with highly stretched spacers. The differences increase as the grafting density decreases and single dendron populations were evident in theta and poor solvent. In poor solvent at low grafting densities, solvent micelles, polymeric pinned lamellae, spherical and single chain collapsed micelles were observed. The scaling dependence of the height of the dendritic brush at high density brushes for both solvents was found to be in agreement with existing analytical results. PMID:23902025

  1. Weak bond screening system

    NASA Astrophysics Data System (ADS)

    Chuang, S. Y.; Chang, F. H.; Bell, J. R.

    Consideration is given to the development of a weak bond screening system which is based on the utilization of a high power ultrasonic (HPU) technique. The instrumentation of the prototype bond strength screening system is described, and the adhesively bonded specimens used in the system developmental effort are detailed. Test results obtained from these specimens are presented in terms of bond strength and level of high power ultrasound irradiation. The following observations were made: (1) for Al/Al specimens, 2.6 sec of HPU irradiation will screen weak bond conditions due to improper preparation of bonding surfaces; (2) for composite/composite specimens, 2.0 sec of HPU irradiation will disrupt weak bonds due to under-cured conditions; (3) for Al honeycomb core with composite skin structure, 3.5 sec of HPU irradiation will disrupt weak bonds due to bad adhesive or oils contamination of bonding surfaces; and (4) for Nomex honeycomb with Al skin structure, 1.3 sec of HPU irradiation will disrupt weak bonds due to bad adhesive.

  2. Epidemiology of organic solvents and connective tissue disease

    PubMed Central

    Garabrant, David H; Dumas, Constantine

    2000-01-01

    Case reports suggest that solvents are associated with various connective tissue diseases (systemic sclerosis, scleroderma, undifferentiated connective tissue disease, systemic lupus erythematosis, and rheumatoid arthritis), particularly systemic sclerosis. A small number of epidemiological studies have shown statistically significant but weak associations between solvent exposure, systemic sclerosis, and undifferentiated connective tissue disease. However, the interpretation of these positive findings is tempered by a lack of replication, an inability to specify which solvents convey risk, and an absence of increasing risk with increasing exposure. Existing studies, on aggregate, do not show conclusively that solvents (either as a group of chemicals or individual chemicals) are causally associated with any connective tissue disease. Further investigations should be carried out to replicate the positive existing findings and to specify the solvents and circumstances of exposure that carry risk. PMID:11094414

  3. Modeling, Measuring, and Compensating Color Weak Vision

    NASA Astrophysics Data System (ADS)

    Oshima, Satoshi; Mochizuki, Rika; Lenz, Reiner; Chao, Jinhui

    2016-06-01

    We use methods from Riemann geometry to investigate transformations between the color spaces of color-normal and color weak observers. The two main applications are the simulation of the perception of a color weak observer for a color normal observer and the compensation of color images in a way that a color weak observer has approximately the same perception as a color normal observer. The metrics in the color spaces of interest are characterized with the help of ellipsoids defined by the just-noticable-differences between color which are measured with the help of color-matching experiments. The constructed mappings are isometries of Riemann spaces that preserve the perceived color-differences for both observers. Among the two approaches to build such an isometry, we introduce normal coordinates in Riemann spaces as a tool to construct a global color-weak compensation map. Compared to previously used methods this method is free from approximation errors due to local linearizations and it avoids the problem of shifting locations of the origin of the local coordinate system. We analyse the variations of the Riemann metrics for different observers obtained from new color matching experiments and describe three variations of the basic method. The performance of the methods is evaluated with the help of semantic differential (SD) tests.

  4. Weak shock reflection

    NASA Astrophysics Data System (ADS)

    Hunter, John K.; Brio, Moysey

    2000-05-01

    We present numerical solutions of a two-dimensional inviscid Burgers equation which provides an asymptotic description of the Mach reflection of weak shocks. In our numerical solutions, the incident, reflected, and Mach shocks meet at a triple point, and there is a supersonic patch behind the triple point, as proposed by Guderley for steady weak-shock reflection. A theoretical analysis indicates that there is an expansion fan at the triple point, in addition to the three shocks. The supersonic patch is extremely small, and this work is the first time it has been resolved.

  5. In praise of weakness

    NASA Astrophysics Data System (ADS)

    Steinberg, Aephraim; Feizpour, Amir; Rozema; Mahler; Hayat

    2013-03-01

    Quantum physics is being transformed by a radical new conceptual and experimental approach known as weak measurement that can do everything from tackling basic quantum mysteries to mapping the trajectories of photons in a Young's double-slit experiment. Aephraim Steinberg, Amir Feizpour, Lee Rozema, Dylan Mahler and Alex Hayat unveil the power of this new technique.

  6. True and masked three-coordinate T-shaped platinum(II) intermediates

    PubMed Central

    Ortuño, Manuel A

    2013-01-01

    Summary Although four-coordinate square-planar geometries, with a formally 16-electron counting, are absolutely dominant in isolated Pt(II) complexes, three-coordinate, 14-electron Pt(II) complexes are believed to be key intermediates in a number of platinum-mediated organometallic transformations. Although very few authenticated three-coordinate Pt(II) complexes have been characterized, a much larger number of complexes can be described as operationally three-coordinate in a kinetic sense. In these compounds, which we have called masked T-shaped complexes, the fourth position is occupied by a very weak ligand (agostic bond, solvent molecule or counteranion), which can be easily displaced. This review summarizes the structural features of the true and masked T-shaped Pt(II) complexes reported so far and describes synthetic strategies employed for their formation. Moreover, recent experimental and theoretical reports are analyzed, which suggest the involvement of such intermediates in reaction mechanisms, particularly C–H bond-activation processes. PMID:23946831

  7. Halogenated solvent remediation

    DOEpatents

    Sorenson, Kent S.

    2004-08-31

    Methods for enhancing bioremediation of ground water contaminated with nonaqueous halogenated solvents are disclosed. A preferred method includes adding a composition to the ground water wherein the composition is an electron donor for microbe-mediated reductive dehalogenation of the halogenated solvents and enhances mass transfer of the halogenated solvents from residual source areas into the aqueous phase of the ground water. Illustrative compositions effective in these methods include surfactants such as C.sub.2 -C.sub.4 carboxylic acids and hydroxy acids, salts thereof, esters of C.sub.2 -C.sub.4 carboxylic acids and hydroxy acids, and mixtures thereof. Especially preferred compositions for use in these methods include lactic acid, salts of lactic acid, such as sodium lactate, lactate esters, and mixtures thereof. The microbes are either indigenous to the ground water, or such microbes can be added to the ground water in addition to the composition.

  8. Halogenated solvent remediation

    DOEpatents

    Sorenson, Jr., Kent S.

    2008-11-11

    Methods for enhancing bioremediation of ground water contaminated with nonaqueous halogenated solvents are disclosed. An illustrative method includes adding an electron donor for microbe-mediated anaerobic reductive dehalogenation of the halogenated solvents, which electron donor enhances mass transfer of the halogenated solvents from residual source areas into the aqueous phase of the ground water. Illustrative electron donors include C.sub.2-C.sub.4 carboxylic acids and hydroxy acids, salts thereof, esters of C.sub.2-C.sub.4 carboxylic acids and hydroxy acids, and mixtures thereof, of which lactic acid, salts of lactic acid--such as sodium lactate, lactate esters, and mixtures thereof are particularly illustrative. The microbes are either indigenous to the ground water, or such microbes can be added to the ground water in addition to the electron donor.

  9. Separation by solvent extraction

    DOEpatents

    Holt, Jr., Charles H.

    1976-04-06

    17. A process for separating fission product values from uranium and plutonium values contained in an aqueous solution, comprising adding an oxidizing agent to said solution to secure uranium and plutonium in their hexavalent state; contacting said aqueous solution with a substantially water-immiscible organic solvent while agitating and maintaining the temperature at from -1.degree. to -2.degree. C. until the major part of the water present is frozen; continuously separating a solid ice phase as it is formed; separating a remaining aqueous liquid phase containing fission product values and a solvent phase containing plutonium and uranium values from each other; melting at least the last obtained part of said ice phase and adding it to said separated liquid phase; and treating the resulting liquid with a new supply of solvent whereby it is practically depleted of uranium and plutonium.

  10. Breathing with chlorinated solvents

    SciTech Connect

    McCarty, P.L.

    1997-06-06

    Chlorinated solvents are effective cleaners and in the past dirted solvents were dumped into landfills, stored in tanks that often leaked, or spilled. As a result the most common contaminants of organic groundwater at hazardous waste sites are the two major chlorinated solvents - tetrachloroethylene (PCE) and trichloroethylene (TCE). Both are suspected carcinogens and both are highly resistant to biodegradation. Now however, there is a report of a bacterium that can remove all of the chlorine atoms from both by halorespiration to form ethene, an innocuous end product. This article goes on to discuss the background of biodegradation of chlorinated compounds, why it is so difficult, and what the future is in this area. 9 refs., 1 fig.

  11. Safe battery solvents

    DOEpatents

    Harrup, Mason K.; Delmastro, Joseph R.; Stewart, Frederick F.; Luther, Thomas A.

    2007-10-23

    An ion transporting solvent maintains very low vapor pressure, contains flame retarding elements, and is nontoxic. The solvent in combination with common battery electrolyte salts can be used to replace the current carbonate electrolyte solution, creating a safer battery. It can also be used in combination with polymer gels or solid polymer electrolytes to produce polymer batteries with enhanced conductivity characteristics. The solvents may comprise a class of cyclic and acyclic low molecular weight phosphazenes compounds, comprising repeating phosphorus and nitrogen units forming a core backbone and ion-carrying pendent groups bound to the phosphorus. In preferred embodiments, the cyclic phosphazene comprises at least 3 phosphorus and nitrogen units, and the pendent groups are polyethers, polythioethers, polyether/polythioethers or any combination thereof, and/or other groups preferably comprising other atoms from Group 6B of the periodic table of elements.

  12. How Do Teachers Coordinate Their Work? A Framing Approach

    ERIC Educational Resources Information Center

    Dumay, Xavier

    2014-01-01

    Since the 1970s, schools have been characterized as loosely coupled systems, meaning that the teachers' work is weakly coordinated at the local level. Nonetheless, few studies have focused on the local variations of coordination modes, their sources and their nature. In this article, the process of local coordination of the teachers'…

  13. Hypernuclear Weak Decays

    NASA Astrophysics Data System (ADS)

    Itonaga, K.; Motoba, T.

    The recent theoretical studies of Lambda-hypernuclear weak decaysof the nonmesonic and pi-mesonic ones are developed with the aim to disclose the link between the experimental decay observables and the underlying basic weak decay interactions and the weak decay mechanisms. The expressions of the nonmesonic decay rates Gamma_{nm} and the decay asymmetry parameter alpha_1 of protons from the polarized hypernuclei are presented in the shell model framework. We then introduce the meson theoretical Lambda N -> NN interactions which include the one-meson exchanges, the correlated-2pi exchanges, and the chiral-pair-meson exchanges. The features of meson exchange potentials and their roles on the nonmesonic decays are discussed. With the adoption of the pi + 2pi/rho + 2pi/sigma + omega + K + rhopi/a_1 + sigmapi/a_1 exchange potentials, we have carried out the systematic calculations of the nonmesonic decay observables for light-to-heavy hypernuclei. The present model can account for the available experimental data of the decay rates, Gamma_n/Gamma_p ratios, and the intrinsic asymmetry parameters alpha_Lambda (alpha_Lambda is related to alpha_1) of emitted protons well and consistently within the error bars. The hypernuclear lifetimes are evaluated by converting the total weak decay rates Gamma_{tot} = Gamma_pi + Gamma_{nm} to tau, which exhibit saturation property for the hypernuclear mass A ≥ 30 and agree grossly well with experimental data for the mass range from light to heavy hypernuclei except for the very light ones. Future extensions of the model and the remaining problems are also mentioned. The pi-mesonic weak processes are briefly surveyed, and the calculations and predictions are compared and confirmed by the recent high precision FINUDA pi-mesonic decay data. This shows that the theoretical basis seems to be firmly grounded.

  14. Correlation of 1JCH spin-spin coupling constants and their solvent sensitivities

    NASA Astrophysics Data System (ADS)

    Shahkhatuni, Astghik A.; Sahakyan, Aleksandr B.; Shahkhatuni, Aleksan G.; Mamyan, Suren S.; Panosyan, Henry A.

    2012-07-01

    The solvent induced changes of one-bond spin-spin coupling constants (SSCC) of several substituted methanes are investigated in solvents with different polarities. The correlation between solute SSCC and solvent dielectric constant is used to estimate the solvent effect-free ('pure') values of SSCCs by linear extrapolation to zero in reaction field coordinates. The obtained 'pure' SSCCs are close to the values, measured by gas phase NMR spectroscopy or predicted by quantum chemical calculations for isolated molecules. The slopes of SSCC dependencies, interpreted as solvent sensitivities of each molecule, are linearly correlated with the 'pure' values of SSCC.

  15. Underwater contact adhesion and microarchitecture in polyelectrolyte complexes actuated by solvent exchange

    PubMed Central

    Seo, Sungbaek; Kaufman, Yair; Israelachvili, Jacob N.; Waite, J. Herbert

    2016-01-01

    Polyelectrolyte complexation is critical to the formation and properties of many biological and polymeric materials, and is typically initiated by aqueous mixing1 followed by fluid–fluid phase separation, such as coacervation2–5. Yet little to nothing is known about how coacervates evolve into intricate solid microarchitectures. Inspired by the chemical features of the cement proteins of the sandcastle worm, here we report a versatile and strong wet-contact microporous adhesive resulting from polyelectrolyte complexation triggered by solvent exchange. After premixing a catechol-functionalized weak polyanion with a polycation in dimethyl sulphoxide (DMSO), the solution was applied underwater to various substrates whereupon electrostatic complexation, phase inversion, and rapid setting were simultaneously actuated by water–DMSO solvent exchange. Spatial and temporal coordination of complexation, inversion and setting fostered rapid (~25 s) and robust underwater contact adhesion (Wad ≥ 2 J m−2) of complexed catecholic polyelectrolytes to all tested surfaces including plastics, glasses, metals and biological materials. PMID:26779881

  16. Underwater contact adhesion and microarchitecture in polyelectrolyte complexes actuated by solvent exchange.

    PubMed

    Zhao, Qiang; Lee, Dong Woog; Ahn, B Kollbe; Seo, Sungbaek; Kaufman, Yair; Israelachvili, Jacob N; Waite, J Herbert

    2016-04-01

    Polyelectrolyte complexation is critical to the formation and properties of many biological and polymeric materials, and is typically initiated by aqueous mixing followed by fluid-fluid phase separation, such as coacervation. Yet little to nothing is known about how coacervates evolve into intricate solid microarchitectures. Inspired by the chemical features of the cement proteins of the sandcastle worm, here we report a versatile and strong wet-contact microporous adhesive resulting from polyelectrolyte complexation triggered by solvent exchange. After premixing a catechol-functionalized weak polyanion with a polycation in dimethyl sulphoxide (DMSO), the solution was applied underwater to various substrates whereupon electrostatic complexation, phase inversion, and rapid setting were simultaneously actuated by water-DMSO solvent exchange. Spatial and temporal coordination of complexation, inversion and setting fostered rapid (∼25 s) and robust underwater contact adhesion (Wad ≥ 2 J m(-2)) of complexed catecholic polyelectrolytes to all tested surfaces including plastics, glasses, metals and biological materials.

  17. Underwater contact adhesion and microarchitecture in polyelectrolyte complexes actuated by solvent exchange.

    PubMed

    Zhao, Qiang; Lee, Dong Woog; Ahn, B Kollbe; Seo, Sungbaek; Kaufman, Yair; Israelachvili, Jacob N; Waite, J Herbert

    2016-04-01

    Polyelectrolyte complexation is critical to the formation and properties of many biological and polymeric materials, and is typically initiated by aqueous mixing followed by fluid-fluid phase separation, such as coacervation. Yet little to nothing is known about how coacervates evolve into intricate solid microarchitectures. Inspired by the chemical features of the cement proteins of the sandcastle worm, here we report a versatile and strong wet-contact microporous adhesive resulting from polyelectrolyte complexation triggered by solvent exchange. After premixing a catechol-functionalized weak polyanion with a polycation in dimethyl sulphoxide (DMSO), the solution was applied underwater to various substrates whereupon electrostatic complexation, phase inversion, and rapid setting were simultaneously actuated by water-DMSO solvent exchange. Spatial and temporal coordination of complexation, inversion and setting fostered rapid (∼25 s) and robust underwater contact adhesion (Wad ≥ 2 J m(-2)) of complexed catecholic polyelectrolytes to all tested surfaces including plastics, glasses, metals and biological materials. PMID:26779881

  18. Weak Gravitational Lensing

    NASA Astrophysics Data System (ADS)

    Pires, Sandrine; Starck, Jean-Luc; Leonard, Adrienne; Réfrégier, Alexandre

    2012-03-01

    This chapter reviews the data mining methods recently developed to solve standard data problems in weak gravitational lensing. We detail the different steps of the weak lensing data analysis along with the different techniques dedicated to these applications. An overview of the different techniques currently used will be given along with future prospects. Until about 30 years ago, astronomers thought that the Universe was composed almost entirely of ordinary matter: protons, neutrons, electrons, and atoms. The field of weak lensing has been motivated by the observations made in the last decades showing that visible matter represents only about 4-5% of the Universe (see Figure 14.1). Currently, the majority of the Universe is thought to be dark, that is, does not emit electromagnetic radiation. The Universe is thought to be mostly composed of an invisible, pressure less matter - potentially relic from higher energy theories - called "dark matter" (20-21%) and by an even more mysterious term, described in Einstein equations as a vacuum energy density, called "dark energy" (70%). This "dark" Universe is not well described or even understood; its presence is inferred indirectly from its gravitational effects, both on the motions of astronomical objects and on light propagation. So this point could be the next breakthrough in cosmology. Today's cosmology is based on a cosmological model that contains various parameters that need to be determined precisely, such as the matter density parameter Omega_m or the dark energy density parameter Omega_lambda. Weak gravitational lensing is believed to be the most promising tool to understand the nature of dark matter and to constrain the cosmological parameters used to describe the Universe because it provides a method to directly map the distribution of dark matter (see [1,6,60,63,70]). From this dark matter distribution, the nature of dark matter can be better understood and better constraints can be placed on dark energy

  19. Composite weak bosons

    SciTech Connect

    Suzuki, M.

    1988-04-01

    Dynamical mechanism of composite W and Z is studied in a 1/N field theory model with four-fermion interactions in which global weak SU(2) symmetry is broken explicitly by electromagnetic interaction. Issues involved in such a model are discussed in detail. Deviation from gauge coupling due to compositeness and higher order loop corrections are examined to show that this class of models are consistent not only theoretically but also experimentally.

  20. Sequential weak measurement

    SciTech Connect

    Mitchison, Graeme; Jozsa, Richard; Popescu, Sandu |||

    2007-12-15

    The notion of weak measurement provides a formalism for extracting information from a quantum system in the limit of vanishing disturbance to its state. Here we extend this formalism to the measurement of sequences of observables. When these observables do not commute, we may obtain information about joint properties of a quantum system that would be forbidden in the usual strong measurement scenario. As an application, we provide a physically compelling characterization of the notion of counterfactual quantum computation.

  1. Organic solvent topical report

    SciTech Connect

    Cowley, W.L.

    1998-04-30

    This report is the technical basis for the accident and consequence analyses used in the Hanford Tank Farms Basis for Interim Operation. The report also contains the scientific and engineering information and reference material needed to understand the organic solvent safety issue. This report includes comments received from the Chemical Reactions Subcommittee of the Tank Advisory Panel.

  2. ONSITE SOLVENT RECOVERY

    EPA Science Inventory

    This study evaluated the product quality, waste reduction/pollution prevention, and economic aspects of three technologies for onsite solvent recovery. The technologies were (1) atmospheric batch distillation, (2) vacuum heat-pump distillation, and (3) low-emission vapor degreas...

  3. Organic solvent topical report

    SciTech Connect

    COWLEY, W.L.

    1999-05-13

    This report provides the basis for closing the organic solvent safety issue. Sufficient information is presented to conclude that risk posed by an organic solvent fire is within risk evaluation guidelines. This report updates information contained in Analysis of Consequences of Postulated Solvent Fires in Hanford Site Waste Tanks. WHC-SD-WM-CN-032. Rev. 0A (Cowley et al. 1996). However, this document will not replace Cowley et al (1996) as the primary reference for the Basis for Interim Operation (BIO) until the recently submitted BIO amendment (Hanson 1999) is approved by the US Department of Energy. This conclusion depends on the use of controls for preventing vehicle fuel fires and for limiting the use of flame cutting in areas where hot metal can fall on the waste surface.The required controls are given in the Tank Waste Remediation System Technical Safety Requirements (Noorani 1997b). This is a significant change from the conclusions presented in Revision 0 of this report. Revision 0 of this calcnote concluded that some organic solvent fire scenarios exceeded risk evaluation guidelines, even with controls imposed.

  4. DESIGNING GREENER SOLVENTS

    EPA Science Inventory

    Computer-aided design of chemicals and chemical mixtures provides a powerful tool to help engineers identify cleaner process designs and more-benign alternatives to toxic industrial solvents. Three software programs are discussed: (1) PARIS II (Program for Assisting the Replaceme...

  5. Solvent vapor collector

    DOEpatents

    Ellison, Kenneth; Whike, Alan S.

    1979-01-30

    A solvent vapor collector is mounted on the upstream inlet end of an oven having a gas-circulating means and intended for curing a coating applied to a strip sheet metal at a coating station. The strip sheet metal may be hot and solvent vapors are evaporated at the coating station and from the strip as it passes from the coating station to the oven. Upper and lower plenums within a housing of the collector are supplied with oven gases or air from the gas-circulating means and such gases or air are discharged within the collector obliquely in a downstream direction against the strip passing through that collector to establish downstream gas flows along the top and under surfaces of the strip so as, in turn, to induct solvent vapors into the collector at the coating station. A telescopic multi-piece shroud is usefully provided on the housing for movement between an extended position in which it overlies the coating station to collect solvent vapors released thereat and a retracted position permitting ready cleaning and adjustment of that coating station.

  6. Influence of binary swelling solvents: Mechanism of action

    SciTech Connect

    Ding, R.; Tucker, D.; Kispert, L.D.

    1995-12-31

    This study addresses the dramatic up-take of a poor swelling solvent in Argonne Premium Coal Samples (APCS), Illinois No. 6, Beulah-Zap and Lewiston-Stockton when such a solvent is spiked with various amounts of the strong swelling solvent, pyridine. The unexpected up-take can be explained in terms of four different processes: (1) disruption of weak hydrogen bonds which isolate the interconnected micropore system; (2) disruption of weak hydrogen bonds which protect individual micropores; (3) competition of pyridine for the active sites involved in the hydrogen bonds or the {open_quotes}poisoning{close_quotes} of active sites; and (4) disruption of stronger hydrogen bonds within the macromolecules which causes an opening of the structure. When more than 5% pyridine is used, no additional disruption of the hydrogen-bonded network occurs. The structural changes were monitored by spin probe incorporation which was measured by EPR spectroscopy.

  7. Solvent-Ion Interactions in Salt Water: A Simple Experiment.

    ERIC Educational Resources Information Center

    Willey, Joan D.

    1984-01-01

    Describes a procedurally quick, simple, and inexpensive experiment which illustrates the magnitude and some effects of solvent-ion interactions in aqueous solutions. Theoretical information, procedures, and examples of temperature, volume and hydration number calculations are provided. (JN)

  8. Emergent soft monopole modes in weakly bound deformed nuclei

    NASA Astrophysics Data System (ADS)

    Pei, J. C.; Kortelainen, M.; Zhang, Y. N.; Xu, F. R.

    2014-11-01

    Based on the Hartree-Fock-Bogoliubov solutions in large deformed coordinate spaces, the finite amplitude method for the quasiparticle random-phase approximation (FAM-QRPA) has been implemented, providing a suitable approach to probing collective excitations of weakly bound nuclei embedded in the continuum. The monopole excitation modes in magnesium isotopes up to the neutron drip line have been studied with the FAM-QRPA framework on both the coordinate-space and harmonic oscillator basis methods. Enhanced soft monopole strengths and collectivity as a result of weak-binding effects have been unambiguously demonstrated.

  9. Gravitational anomaly and Hawking radiation near a weakly isolated horizon

    SciTech Connect

    Wu Xiaoning; Huang Chaoguang; Sun Jiarui

    2008-06-15

    Based on the idea of the work by Wilczek and his collaborators, we consider the gravitational anomaly near a weakly isolated horizon. We find that there exists a universal choice of tortoise coordinate for any weakly isolated horizon. Under this coordinate, the leading behavior of a quite arbitrary scalar field near a horizon is a 2-dimensional chiral scalar field. This means we can extend the idea of Wilczek and his collaborators to more general cases and show the relation between gravitational anomaly and Hawking radiation is a universal property of a black hole horizon.

  10. Gravitational anomaly and Hawking radiation near a weakly isolated horizon

    NASA Astrophysics Data System (ADS)

    Wu, Xiaoning; Huang, Chao-Guang; Sun, Jia-Rui

    2008-06-01

    Based on the idea of the work by Wilczek and his collaborators, we consider the gravitational anomaly near a weakly isolated horizon. We find that there exists a universal choice of tortoise coordinate for any weakly isolated horizon. Under this coordinate, the leading behavior of a quite arbitrary scalar field near a horizon is a 2-dimensional chiral scalar field. This means we can extend the idea of Wilczek and his collaborators to more general cases and show the relation between gravitational anomaly and Hawking radiation is a universal property of a black hole horizon.

  11. DESIGNING ENVIRONMENTALLY BENIGN SOLVENT SUBSTITUTES

    EPA Science Inventory

    Since the signing of 1987 Montreal Protocol, reducing and eliminating the use of harmful solvents has become an internationally imminent environmental protection mission. Solvent substitution is an effective way to achieve this goal. The Program for Assisting the Replacement of...

  12. Solvent dewaxing of lubricating oils

    SciTech Connect

    Sequeira, A. Jr.

    1991-04-09

    This paper describes improvement in a process for producing a dewaxed lubricating oil from a wax-bearing mineral oil by the steps comprising; mixing the oil with a dewaxing solvent thereby forming an oil-solvent mixture, chilling the oil-solvent mixture to a dewaxing temperature thereby crystallizing the wax and forming an oil-solvent crystalline wax mixture, separating the oil-solvent-crystalline wax mixture to form a dewaxed oil-solvent mixture and crystalline wax, steam stripping the dewaxed oil-solvent mixture at a temperature of 300{degrees}F to 600{degrees}F and pressure of 1 atm to 3 atm, to yield a solvent free dewaxed oil.

  13. `Weak A' phenotypes

    PubMed Central

    Cartron, J. P.; Gerbal, A.; Hughes-Jones, N. C.; Salmon, C.

    1974-01-01

    Thirty-five weak A samples including fourteen A3, eight Ax, seven Aend, three Am and three Ae1 were studied in order to determine their A antigen site density, using an IgG anti-A labelled with 125I. The values obtained ranged between 30,000 A antigen sites for A3 individuals, and 700 sites for the Ae1 red cells. The hierarchy of values observed made it possible to establish a quantitative relationship between the red cell agglutinability of these phenotypes measured under standard conditions, and their antigen site density. PMID:4435836

  14. Weakly broken galileon symmetry

    SciTech Connect

    Pirtskhalava, David; Santoni, Luca; Trincherini, Enrico; Vernizzi, Filippo

    2015-09-01

    Effective theories of a scalar ϕ invariant under the internal galileon symmetryϕ→ϕ+b{sub μ}x{sup μ} have been extensively studied due to their special theoretical and phenomenological properties. In this paper, we introduce the notion of weakly broken galileon invariance, which characterizes the unique class of couplings of such theories to gravity that maximally retain their defining symmetry. The curved-space remnant of the galileon’s quantum properties allows to construct (quasi) de Sitter backgrounds largely insensitive to loop corrections. We exploit this fact to build novel cosmological models with interesting phenomenology, relevant for both inflation and late-time acceleration of the universe.

  15. Weak decay of hypernuclei

    SciTech Connect

    Grace, R.

    1983-01-01

    The Moby Dick spectrometer (at BNL) in coincidence with a range spectrometer and a TOF neutron detector will be used to study the weak decay modes of /sup 12/C. The Moby Dick spectrometer will be used to reconstruct and tag events in which specific hypernuclear states are formed in the reaction K/sup -/ + /sup 12/C ..-->.. ..pi../sup -/ + /sup 12/C. Subsequent emission of decay products (pions, protons and neutrons) in coincidence with the fast forward pion will be detected in a time and range spectrometer, and a neutron detector.

  16. Weakly broken galileon symmetry

    SciTech Connect

    Pirtskhalava, David; Santoni, Luca; Trincherini, Enrico; Vernizzi, Filippo E-mail: luca.santoni@sns.it E-mail: filippo.vernizzi@cea.fr

    2015-09-01

    Effective theories of a scalar φ invariant under the internal galileon symmetry φ→φ+b{sub μ} x{sup μ} have been extensively studied due to their special theoretical and phenomenological properties. In this paper, we introduce the notion of weakly broken galileon invariance, which characterizes the unique class of couplings of such theories to gravity that maximally retain their defining symmetry. The curved-space remnant of the galileon's quantum properties allows to construct (quasi) de Sitter backgrounds largely insensitive to loop corrections. We exploit this fact to build novel cosmological models with interesting phenomenology, relevant for both inflation and late-time acceleration of the universe.

  17. Solvent substitution for electronic products

    SciTech Connect

    Benkovich, M.K.

    1992-01-01

    Allied-Signal Inc., Kansas City Division (KCD), manufactures the electrical, electrochemical, mechanical, and plastic components for nuclear weapons. The KCD has made a commitment to eliminate the use of chlorohydrocarbon (CHC) and chlorofluorocarbon (CFC) solvents to the greatest technical extent possible consistent with nuclear safety and stockpile reliability requirements. Current cleaning processes in the production departments use trichloroethylene, 1,1,1-trichloroethane, and various CFC-113 based solvents. Several non-halogenated solvents (Solvent A - an aqueous solvent based on N,N-dimethylacetamide, Solvent B - an aqueous mixture of ethanol amines, Solvent C - a hydrocarbon solvent based on octadecyl acetate, Solvent D - a terpene (d-limonene) hydrocarbon solvent combined with emulsifiers, Solvent E - a terpene (d-limonene) hydrocarbon solvent combined with a separation agent, d-limonene, and isopropyl alcohol) were evaluated to determine the most effective, non-chlorinated, non-fluorinated, alternate solvent cleaning system. All of these solvents were evaluated using current manual spray cleaning processes. The solvents were evaluated for their effectiveness in removing a rosin based RMA solder flux, a particular silicone mold release, and oils, greases, mold releases, resins, etc. The Meseran Surface Analyzer was used to measure organic contamination on the samples before and after cleaning. An Omega Meter Model 600 was also used to detect solder flux residues. Solvents C, D, E and d-limonene the best alternatives to trichloroethylene for removing all of the contaminants tested. For this particular electronic assembly, d-limonene was chosen as the alternate because of material compatibility and long-term reliability concerns.

  18. Solvent Immersion Imprint Lithography

    SciTech Connect

    Vasdekis, Andreas E.; Wilkins, Michael J.; Grate, Jay W.; Kelly, Ryan T.; Konopka, Allan; Xantheas, Sotiris S.; Chang, M. T.

    2014-06-21

    The mechanism of polymer disolution was explored for polymer microsystem prototyping, including microfluidics and optofluidics. Polymer films are immersed in a solvent, imprinted and finally brought into contact with a non-modified surface to permanently bond. The underlying polymer-solvent interactions were experimentally and theoretically investigated, and enabled rapid polymer microsystem prototyping. During imprinting, small molecule integration in the molded surfaces was feasible, a principle applied to oxygen sensing. Polystyrene (PS) was employed for microbiological studies at extreme environmental conditions. The thermophile anaerobe Clostridium Thermocellum was grown in PS pore-scale micromodels, revealing a double mean generation lifetime than under ideal culture conditions. Microsystem prototyping through directed polymer dissolution is simple and accessible, while simultaneous patterning, bonding, and surface/volume functionalization are possible in less than one minute.

  19. Solvent selection for the extraction of ethanol from aqueous solutions

    SciTech Connect

    Koullas, D.P.; Umealu, O.S.; Koukios, E.G.

    1999-08-01

    Several organic solvents were examined as potential separating agents for ethanol recovery from aqueous solutions by liquid-liquid extraction. Phase composition determinations for five promising ethanol-water-solvent systems at 20 and 40 C and two solvent-to-feed ratios show that isoamyl acetate (IAA) and isooctyl alcohol (IOA) along with n-butyl acetate (BA) present a greater potential than dibutyl ether and dibutyl oxalate. Tie-line liquid-liquid equilibrium data at 25 C for the three promising solvents (IAA, IOA, and BA) were collected and analyzed. Both IAA and IOA were found to be very good separating agents, exhibiting ethanol distribution coefficients greater than 1, and separation factors in Bancroft coordinates of the order of 70 and 2,000, respectively.

  20. PARIS II: DESIGNING GREENER SOLVENTS

    EPA Science Inventory

    PARIS II (the program for assisting the replacement of industrial solvents, version II), developed at the USEPA, is a unique software tool that can be used for customizing the design of replacement solvents and for the formulation of new solvents. This program helps users avoid ...

  1. Hazardous solvent substitution

    SciTech Connect

    Twitchell, K.E.

    1995-11-01

    Eliminating hazardous solvents is good for the environment, worker safety, and the bottom line. However, even though we are motivated to find replacements, the big question is `What can we use as replacements for hazardous solvents?`You, too, can find replacements for your hazardous solvents. All you have to do is search for them. Search through the vendor literature of hundreds of companies with thousands of products. Ponder the associated material safety data sheets, assuming of course that you can obtain them and, having obtained them, that you can read them. You will want to search the trade magazines and other sources for product reviews. You will want to talk to users about how well the product actually works. You may also want to check US Environmental Protection Agency (EPA) and other government reports for toxicity and other safety information. And, of course, you will want to compare the product`s constituent chemicals with the many hazardous constituency lists to ensure the safe and legal use of the product in your workplace.

  2. A coordination chemistry study of hydrated and solvated cationic vanadium ions in oxidation states +III, +IV, and +V in solution and solid state.

    PubMed

    Krakowiak, Joanna; Lundberg, Daniel; Persson, Ingmar

    2012-09-17

    The coordination chemistry of hydrated and solvated vanadium(III), oxovanadium(IV), and dioxovanadium(V) ions in the oxygen-donor solvents water, dimethyl sulfoxide (DMSO), and N,N'-dimethylpropyleneurea (DMPU) has been studied in solution by extended X-ray absorption fine structure (EXAFS) and large-angle X-ray scattering (LAXS) and in the solid state by single-crystal X-ray diffraction and EXAFS. The hydrated vanadium(III) ion has a regular octahedral configuration with a mean V-O bond distance of 1.99 Å. In the hydrated and DMSO-solvated oxovanadium(IV) ions, vanadium binds strongly to an oxo group at ca. 1.6 Å. The solvent molecule trans to the oxo group is very weakly bound, at ca. 2.2 Å, while the remaining four solvent molecules, with a mean V-O bond distance of 2.0 Å, form a plane slightly below the vanadium atom; the mean O═V-O(perp) bond angle is ca. 98°. In the DMPU-solvated oxovanadium(IV) ion, the space-demanding properties of the DMPU molecule leave no solvent molecule in the trans position to the oxo group, which reduces the coordination number to 5. The O═V-O bond angle is consequently much larger, 107°, and the mean V═O and V-O bond distances decrease to 1.58 and 1.97 Å, respectively. The hydrated and DMSO-solvated dioxovanadium(V) ions display a very distorted octahedral configuration with the oxo groups in the cis position with a mean V═O bond distance of 1.6 Å and a O═V═O bond angle of ca. 105°. The solvent molecules trans to the oxo groups are weakly bound, at ca. 2.2 Å, while the remaining two have bond distances of 2.02 Å. The experimental studies of the coordination chemistry of hydrated and solvated vanadium(III,IV,V) ions are complemented by summarizing previously reported crystal structures to yield a comprehensive description of the coordination chemistry of vanadium with oxygen-donor ligands.

  3. Solvent replacement for green processing.

    PubMed Central

    Sherman, J; Chin, B; Huibers, P D; Garcia-Valls, R; Hatton, T A

    1998-01-01

    The implementation of the Montreal Protocol, the Clean Air Act, and the Pollution Prevention Act of 1990 has resulted in increased awareness of organic solvent use in chemical processing. The advances made in the search to find "green" replacements for traditional solvents are reviewed, with reference to solvent alternatives for cleaning, coatings, and chemical reaction and separation processes. The development of solvent databases and computational methods that aid in the selection and/or design of feasible or optimal environmentally benign solvent alternatives for specific applications is also discussed. Images Figure 2 Figure 3 PMID:9539018

  4. SOLVENT FIRE BY-PRODUCTS

    SciTech Connect

    Walker, D; Samuel Fink, S

    2006-05-22

    Southwest Research Institute (SwRI) conducted a burn test of the Caustic-Side Solvent Extraction (CSSX) solvent to determine the combustion products. The testing showed hydrogen fluoride gas is not a combustion product from a solvent fire when up to 70% of the solvent is consumed. The absence of HF in the combustion gases may reflect concentration of the modifier containing the fluoride groups in the unburned portion. SwRI reported results for other gases (CO, HCN, NOx, formaldehyde, and hydrocarbons). The results, with other supporting information, can be used for evaluating the consequences of a facility fire involving the CSSX solvent inventory.

  5. Weakly relativistic plasma expansion

    SciTech Connect

    Fermous, Rachid Djebli, Mourad

    2015-04-15

    Plasma expansion is an important physical process that takes place in laser interactions with solid targets. Within a self-similar model for the hydrodynamical multi-fluid equations, we investigated the expansion of both dense and under-dense plasmas. The weakly relativistic electrons are produced by ultra-intense laser pulses, while ions are supposed to be in a non-relativistic regime. Numerical investigations have shown that relativistic effects are important for under-dense plasma and are characterized by a finite ion front velocity. Dense plasma expansion is found to be governed mainly by quantum contributions in the fluid equations that originate from the degenerate pressure in addition to the nonlinear contributions from exchange and correlation potentials. The quantum degeneracy parameter profile provides clues to set the limit between under-dense and dense relativistic plasma expansions at a given density and temperature.

  6. Next Generation Solvent (NGS): Development for Caustic-Side Solvent Extraction of Cesium

    SciTech Connect

    Moyer, Bruce A.; Birdwell, Jr, Joseph F.; Bonnesen, Peter V.; Bruffey, Stephanie H.; Delmau, Laetitia Helene; Duncan, Nathan C.; Ensor, Dale; Hill, Talon G.; Lee, Denise L.; Rajbanshi, Arbin; Roach, Benjamin D.; Szczygiel, Patricia L.; Frederick V. Sloop, Jr.; Stoner, Erica L.; Williams, Neil J.

    2014-03-01

    This report summarizes the FY 2010 and 2011 accomplishments at Oak Ridge National Laboratory (ORNL) in developing the Next Generation Caustic-Side Solvent Extraction (NG-CSSX) process, referred to commonly as the Next Generation Solvent (NGS), under funding from the U.S. Department of Energy, Office of Environmental Management (DOE-EM), Office of Technology Innovation and Development. The primary product of this effort is a process solvent and preliminary flowsheet capable of meeting a target decontamination factor (DF) of 40,000 for worst-case Savannah River Site (SRS) waste with a concentration factor of 15 or higher in the 18-stage equipment configuration of the SRS Modular Caustic-Side Solvent Extraction Unit (MCU). In addition, the NG-CSSX process may be readily adapted for use in the SRS Salt Waste Processing Facility (SWPF) or in supplemental tank-waste treatment at Hanford upon appropriate solvent or flowsheet modifications. Efforts in FY 2010 focused on developing a solvent composition and process flowsheet for MCU implementation. In FY 2011 accomplishments at ORNL involved a wide array of chemical-development activities and testing up through single-stage hydraulic and mass-transfer tests in 5-cm centrifugal contactors. Under subcontract from ORNL, Argonne National Laboratory (ANL) designed a preliminary flowsheet using ORNL cesium distribution data, and Tennessee Technological University confirmed a chemical model for cesium distribution ratios (DCs) as a function of feed composition. Interlaboratory efforts were coordinated with complementary engineering tests carried out (and reported separately) by personnel at Savannah River National Laboratory (SRNL) and Savannah River Remediation (SRR) with helpful advice by Parsons Engineering and General Atomics on aspects of possible SWPF implementation.

  7. Next Generation Solvent Development for Caustic-Side Solvent Extraction of Cesium

    SciTech Connect

    Moyer, Bruce A.; Birdwell, Joseph F.; Bonnesen, Peter V.; Bruffey, Stephanie

    2014-03-01

    This report summarizes the FY 2010 and 2011 accomplishments at Oak Ridge National Laboratory (ORNL) in developing the Next Generation Caustic-Side Solvent Extraction (NG-CSSX) process, referred to commonly as the Next Generation Solvent (NGS), under funding from the U.S. Department of Energy, Office of Environmental Management (DOE-EM), Office of Technology Innovation and Development. The primary product of this effort is a process solvent and preliminary flowsheet capable of meeting a target decontamination factor (DF) of 40,000 for worst-case Savannah River Site (SRS) waste with a concentration factor of 15 or higher in the 18-stage equipment configuration of the SRS Modular Caustic-Side Solvent Extraction Unit (MCU). In addition, the NG-CSSX process may be readily adapted for use in the SRS Salt Waste Processing Facility (SWPF) or in supplemental tank-waste treatment at Hanford upon appropriate solvent or flowsheet modifications. Efforts in FY 2010 focused on developing a solvent composition and process flowsheet for MCU implementation. In FY 2011 accomplishments at ORNL involved a wide array of chemical-development activities and testing up through single-stage hydraulic and mass-transfer tests in 5-cm centrifugal contactors. Under subcontract from ORNL, Argonne National Laboratory (ANL) designed a preliminary flowsheet using ORNL cesium distribution data, and Tennessee Technological University confirmed a chemical model for cesium distribution ratios (DCs) as a function of feed composition. Inter laboratory efforts were coordinated with complementary engineering tests carried out (and reported separately) by personnel at Savannah River National Laboratory (SRNL) and Savannah River Remediation (SRR) with helpful advice by Parsons Engineering and General Atomics on aspects of possible SWPF implementation.

  8. Occupational solvent exposure and cognition

    PubMed Central

    Sabbath, E.L.; Glymour, M.M.; Berr, C.; Singh-Manoux, A.; Zins, M.; Goldberg, M.

    2012-01-01

    Objective: Chronic occupational solvent exposure is associated with long-term cognitive deficits. Cognitive reserve may protect solvent-exposed workers from cognitive impairment. We tested whether the association between chronic solvent exposure and cognition varied by educational attainment, a proxy for cognitive reserve. Methods: Data were drawn from a prospective cohort of French national gas and electricity (GAZEL) employees (n = 4,134). Lifetime exposure to 4 solvent types (chlorinated solvents, petroleum solvents, benzene, and nonbenzene aromatic solvents) was assessed using a validated job-exposure matrix. Education was dichotomized at less than secondary school or below. Cognitive impairment was defined as scoring below the 25th percentile on the Digit Symbol Substitution Test at mean age 59 (SD 2.8; 88% of participants were retired at testing). Log-binomial regression was used to model risk ratios (RRs) for poor cognition as predicted by solvent exposure, stratified by education and adjusted for sociodemographic and behavioral factors. Results: Solvent exposure rates were higher among less-educated patients. Within this group, there was a dose-response relationship between lifetime exposure to each solvent type and RR for poor cognition (e.g., for high exposure to benzene, RR = 1.24, 95% confidence interval 1.09–1.41), with significant linear trends (p < 0.05) in 3 out of 4 solvent types. Recency of solvent exposure also predicted worse cognition among less-educated patients. Among those with secondary education or higher, there was no significant or near-significant relationship between any quantification of solvent exposure and cognition. Conclusions: Solvent exposure is associated with poor cognition only among less-educated individuals. Higher cognitive reserve in the more-educated group may explain this finding. PMID:22641403

  9. Computer simulation of bottle-brush polymers with flexible backbone: Good solvent versus theta solvent conditions

    NASA Astrophysics Data System (ADS)

    Theodorakis, Panagiotis E.; Hsu, Hsiao-Ping; Paul, Wolfgang; Binder, Kurt

    2011-10-01

    By molecular dynamics simulation of a coarse-grained bead-spring-type model for a cylindrical molecular brush with a backbone chain of Nb effective monomers to which with grafting density σ side chains with N effective monomers are tethered, several characteristic length scales are studied for variable solvent quality. Side chain lengths are in the range 5 ⩽ N ⩽ 40, backbone chain lengths are in the range 50 ⩽ Nb ⩽ 200, and we perform a comparison to results for the bond fluctuation model on the simple cubic lattice (for which much longer chains are accessible, Nb ⩽ 1027, and which corresponds to an athermal, very good, solvent). We obtain linear dimensions of the side chains and the backbone chain and discuss their N-dependence in terms of power laws and the associated effective exponents. We show that even at the theta point the side chains are considerably stretched, their linear dimension depending on the solvent quality only weakly. Effective persistence lengths are extracted both from the orientational correlations and from the backbone end-to-end distance; it is shown that different measures of the persistence length (which would all agree for Gaussian chains) are not mutually consistent with each other and depend distinctly both on Nb and the solvent quality. A brief discussion of pertinent experiments is given.

  10. Binary Solvent Organization at Silica/Liquid Interfaces: Preferential Ordering in Acetonitrile-Methanol Mixtures.

    PubMed

    Gobrogge, Eric A; Walker, Robert A

    2014-08-01

    Nonlinear vibrational spectroscopy experiments examined solvent organization at the silica/binary solvent interface where the binary solvent consisted of methanol and acetonitrile in varying mole fractions. Data were compared with surface vibrational spectra acquired from silica surfaces exposed to a vapor phase saturated with the same binary solvent mixtures. Changes in vibrational band intensities suggest that methanol ideally adsorbs to the silica/vapor interface but acetonitrile accumulates in excess relative to vapor-phase composition. At the silica/liquid interface, acetonitrile's signal increases until a solution phase mole fraction of ∼0.85. At higher acetonitrile concentrations, acetonitrile's signal decreases dramatically until only a weak signature persists with the neat solvent. This behavior is ascribed to dipole-paired acetonitrile forming a bilayer with the first sublayer associating with surface silanol groups and a second sublayer consisting of weakly associating, antiparallel partners. On the basis of recent simulations, we propose that the second sublayer accumulates in excess. PMID:26277964

  11. A thermodynamic study of selective solvation in solvent mixtures.

    PubMed

    Cabot, Rafel; Hunter, Christopher A

    2010-04-21

    Changes in the (31)P NMR chemical shift of tri-n-butylphosphine oxide have been measured as function of solvent composition in a number of binary solvent mixtures. The data were analysed using a model that separates the contributions of specific H-bond interactions with the first solvation shell and the non-specific effects of the bulk solvent on the chemical shift. This allowed measurement of equilibrium constants between differently solvated states of the probe and hence thermodynamic quantification of preferential solvation in the binary mixtures. The results are analysed in the context of the electrostatic solvent competition model, which assumes that solvent effects on intermolecular interactions can be interpreted based on the exchange of specific functional group contacts, with minimal involvement of the bulk solvent. The thermodynamic measurements of preferential solvation were used to determine the H-bond donor parameter alpha for cyclohexane, n-octane, n-dodecane, benzene, 1,4-dioxane, carbon tetrachloride, acetone, dichloromethane, dimethyl sulfoxide and chloroform. For solvents where the H-bond donor parameters have been measured as solutes in carbon tetrachloride solution, the H-bond donor parameters measured here for the same compounds as solvents are practically identical, i.e. solute and solvent H-bond parameters are directly interchangable. For alkanes, the experimental H-bond donor parameter is significantly larger than expected based on calculated molecular electrostatic potential surfaces. This might suggest an increase in the relative importance of van der Waals interactions when electrostatic effects are weak. PMID:20449502

  12. Coupling of protein dynamics with the solvent

    NASA Astrophysics Data System (ADS)

    Caliskan, Gokhan; Sauzan, Azzam; Mehtani, Disha; Sokolov, Alexei

    2003-03-01

    Glycerol and trehalose are among the many viscous solvents that are widely used for biostabilization and controlling the dynamics of proteins. It is believed that the suppression of the structural relaxations by high viscosity of solvent is responsible for improved stability in proteins. However, results of [1] and [2] demonstrate stronger suppression of biochemical activity and dynamics of proteins by liquid glycerol than by solid trehalose in a wide temperature range. The authors tried to explain the counterintuitive observations by a possible decoupling of the dynamics of the protein from trehalose. In order to test the validity of this assumption and to investigate the influence of the fast dynamics in proteins, the low frequency Raman scattering spectroscopy technique is used. Both relaxational and vibrational dynamics of glycerol, trehalose, and lysozyme in glycerol and in trehalose are studied in a wide temperature range. Dynamics of lysozyme in glycerol follows the strong temperature dependence of relaxational and vibrational dynamics of the bulk glycerol. On the other hand, the weak temperature dependence of dynamics of lysozyme in trehalose follows exactly the behavior of pure trehalose. This proves that there is a strong dynamic coupling between the protein and the solvents used. Interestingly, stronger relaxations in solid trehalose as compared to liquid glycerol are observed in the GHz region at low temperatures. This could be the reason for the enhanced protein activity observed in trehalose, compared to that in glycerol in this temperature range. Suppression of these fast relaxations should be the key for providing long-term stability to proteins. 1. Sastry, G.M. and N. Agmon, Trehalose prevents myoglobin collapse and preserves its internal mobility. BIOCHEMISTRY, 1997, 36(23): p. 7097-108. 2. Caliskan, G., et al., Influence of solvent on dynamics and stability of a protein. Journal of Non-Crystalline Solids, 2002, 307-310: p. 887-893.

  13. Solvent Blending Strategy to Upgrade MCU CSSX Solvent to Equivalent Next-Generation CSSX Solvent

    SciTech Connect

    Delmau, Laetitia Helene; Moyer, Bruce A

    2012-12-01

    The results of the present study have validated an equal-volume blending strategy for upgrading freshly prepared CSSX solvent to a blended solvent functionally equivalent to NG-CSSX solvent. It is shown that blending fresh CSSX solvent as currently used in MCU with an equal volume of an NG-CSSX solvent concentrate of appropriate composition yields a blended solvent composition (46.5 mM of MaxCalix, 3.5 mM of BOBCalixC6, 0.5 M of Cs-7SB, 3 mM of guanidine suppressor, and 1.5 mM of TOA in Isopar L) that exhibits equivalent batch ESS performance to that of the NG-CSSX solvent containing 50 mM of MaxCalix, 0.5 M of Cs-7SB, and 3 mM of guanidine suppressor in Isopar L. The solvent blend composition is robust to third-phase formation. Results also show that a blend containing up to 60% v/v of CSSX solvent could be accommodated with minimal risk. Extraction and density data for the effect of solvent concentration mimicking diluent evaporation or over-dilution of the equal-volume blended solvent are also given, providing input for setting operational limits. Given that the experiments employed all pristine chemicals, the results do not qualify a blended solvent starting with actual used MCU solvent, which can be expected to have undergone some degree of degradation. Consequently, further work should be considered to evaluate this risk and implement appropriate remediation if needed.

  14. Chemical phenomena in solid-state voltammetry in polymer solvents

    SciTech Connect

    Geng, L.; Reed, R.A.; Kim, M.H.; Wooster, T.T.; Oliver, B.N.; Egekeze, J.; Kennedy, R.T.; Jorgenson, J.W.; Parcher, J.F.; Murray, R.W.

    1989-03-01

    This paper, aimed at delineating significant chemical effects in solid-state voltammetry, describes electrochemical oxidations and reductions of electroactive monomer solutes dissolved in and diffusing through rigid and semirigid polymer electrolyte solvents. Sorption of organic monomer vapors into poly(ethylene oxide) films yields polymer solvents whose chemistry is dominated by that of the sorbed monomer as shown by coordination and precipitation effects. The dynamics of plasticization-induced changes in transport rates are quite rapid. Physical diffusion in the polymer solvent in slow enough that electron hopping reactions measurably enhance charge transport rates; the effect was used to estimate a lower limit for the (Co(bpy)/sub 3/)/sup 2+/+/ self-exchange rate constant of 2 /times/ 10/sup 9/ M/sup /minus/1/ s/sup /minus/1/. It is possible to erect polymeric film transport barriers at the electrode/polymer solvent interface and to measure the rate of permeation of monomer complexes from the polymer solvent into the polymer transport barrier film. Polymeric films of Os and Ru polypyridine complexes can be electropolymerized from polymer solutions of the corresponding monomers. Solid-state voltammetry can be extended to other polymer solvents including sulfonated polystyrene, poly(vinyl chloride), Nafion, and poly(acrylamide) gel.

  15. Nanometrization of Lanthanide-Based Coordination Polymers.

    PubMed

    Neaime, Chrystelle; Daiguebonne, Carole; Calvez, Guillaume; Freslon, Stéphane; Bernot, Kevin; Grasset, Fabien; Cordier, Stéphane; Guillou, Olivier

    2015-11-23

    Heteronuclear lanthanide-based coordination polymers are microcrystalline powders, the luminescence properties of which can be precisely tuned by judicious choice of the rare-earth ions. In this study, we demonstrate that such materials can also be obtained as stable solutions of nanoparticles in non-toxic polyols. Bulk powders of the formula [Ln2-2x Ln'2x (bdc)3 ⋅4 H2 O]∞ (where H2 bdc denotes 1,4-benzene-dicarboxylic acid, 0≤x≤1, and Ln and Ln' denote lanthanide ions of the series La to Tm plus Y) afford nanoparticles that have been characterized by dynamic light-scattering (DLS) and transmission electron microscopy (TEM) measurements. Their luminescence properties are similar to those of the bulk materials. Stabilities versus time and versus dilution with another solvent have been studied. This study has revealed that it is possible to tune the size of the nanoparticles. This process offers a reliable means of synthesizing suspensions of nanoparticles with tunable luminescence properties and tunable size distributions in a green solvent (glycerol). The process is also extendable to other coordination polymers and other solvents (ethylene glycol, for example). It constitutes a new route for the facile solubilization of lanthanide-based coordination polymers. PMID:26471940

  16. Nanometrization of Lanthanide-Based Coordination Polymers.

    PubMed

    Neaime, Chrystelle; Daiguebonne, Carole; Calvez, Guillaume; Freslon, Stéphane; Bernot, Kevin; Grasset, Fabien; Cordier, Stéphane; Guillou, Olivier

    2015-11-23

    Heteronuclear lanthanide-based coordination polymers are microcrystalline powders, the luminescence properties of which can be precisely tuned by judicious choice of the rare-earth ions. In this study, we demonstrate that such materials can also be obtained as stable solutions of nanoparticles in non-toxic polyols. Bulk powders of the formula [Ln2-2x Ln'2x (bdc)3 ⋅4 H2 O]∞ (where H2 bdc denotes 1,4-benzene-dicarboxylic acid, 0≤x≤1, and Ln and Ln' denote lanthanide ions of the series La to Tm plus Y) afford nanoparticles that have been characterized by dynamic light-scattering (DLS) and transmission electron microscopy (TEM) measurements. Their luminescence properties are similar to those of the bulk materials. Stabilities versus time and versus dilution with another solvent have been studied. This study has revealed that it is possible to tune the size of the nanoparticles. This process offers a reliable means of synthesizing suspensions of nanoparticles with tunable luminescence properties and tunable size distributions in a green solvent (glycerol). The process is also extendable to other coordination polymers and other solvents (ethylene glycol, for example). It constitutes a new route for the facile solubilization of lanthanide-based coordination polymers.

  17. Hazardous solvent source reduction

    SciTech Connect

    Callahan, M.S.; Green, B.

    1995-09-01

    This book is written for the managers, production leaders, and operations staff tasked with the job of eliminating hazardous cleaning solvents from their workplace. Information regarding the location, evaluation, and implementation of environmentally preferred cleaning technologies is offered for a broad range of applications. These include: removal of grease and grime from a piece of equipment during maintenance, cleaning small parts before assembly, defluxing printed circuit boards and assemblies, and stripping paint from field vehicles and aircraft. Moving beyond the limits of source reduction alone, this book provides complete information on the planning, staffing, and execution of a pollution prevention program, alternative and in-use cleaner testing, waste recycling and treatment, air emission control, replacement system design, and system economics. For the environmental specialist, this book helps to bridge the gap between regulatory requirements and shop-floor constraints.

  18. Solubilities of p-nitroanilines in various classes of solvents. Specific solute-solvent interactions

    NASA Astrophysics Data System (ADS)

    Huyskens, François; Morissen, Heidi; Huyskens, Pierre

    1998-01-01

    The solubilities ф B in volume fractions of p-nitroaniline (PNA) and N,N-dimethyl p-nitroaniline (N,N-PNA) were determined near 25°C in some 40 solvents belonging to different classes using a thermoturbidimetric method. The ratio between the solubilities of the two compounds can be corrected for the differences in the melting characteristics determined from DSC measurements. The solubilities at 25°C of N,N-PNA have then to be multiplied by the factor 2.72. The corrected ratios {ф PNA}/{ф∗ N,N-PNA} give indications on the formation of H-bonds between the solvent molecules and the NH groups of PNA. This is observed in solvent classes with electron donor oxygens like sulfoxides, ketones, esters and cyclic ethers. However, the ratio {ф PNA}/{ф∗ N,N-PNA} decreases in an homologous series when the molar volume of the solvent increases, indicating that the formation of H-bonds by PNA depends also on the concentration of the active sites in the solvent and that not all the PNA molecules are involved in H-bonding. {ф PNA}/{ф∗ N,N-PNA} is also markedly larger than 2 in the lower alcohols demonstrating the formation of N-HO hydrogen bonds at the end of the self-association chains. The fraction γ of the PNA molecules escaping from H-bonding in the electron donor solvents and in alcohols is quantitatively estimated from the solubility using the equations of the theory of the mobile order and disorder of Huyskens and Ruelle. In nitriles a weak formation of N-HHC bonds is observed. In contrast H-bonds are not observed in nitroalkanes. Unexpectedly the ratio's {ф PNA}/{ф∗ N,N-PNA} are much smaller than 1 in chloro alkanes. The formation of EDA bonds between N,N-PNA and these solvents acting as Lewis acids is therefore probable.

  19. Generalized Born and Explicit Solvent Models for Free Energy Calculations in Organic Solvents: Cyclodextrin Dimerization.

    PubMed

    Zhang, Haiyang; Tan, Tianwei; van der Spoel, David

    2015-11-10

    Evaluation of solvation (binding) free energies with implicit solvent models in different dielectric environments for biological simulations as well as high throughput ligand screening remain challenging endeavors. In order to address how well implicit solvent models approximate explicit ones we examined four generalized Born models (GB(Still), GB(HCT), GB(OBC)I, and GB(OBC)II) for determining the dimerization free energy (ΔG(0)) of β-cyclodextrin monomers in 17 implicit solvents with dielectric constants (D) ranging from 5 to 80 and compared the results to previous free energy calculations with explicit solvents ( Zhang et al. J. Phys. Chem. B 2012 , 116 , 12684 - 12693 ). The comparison indicates that neglecting the environmental dependence of Born radii appears acceptable for such calculations involving cyclodextrin and that the GB(Still) and GB(OBC)I models yield a reasonable estimation of ΔG(0), although the details of binding are quite different from explicit solvents. Large discrepancies between implicit and explicit solvent models occur in high-dielectric media with strong hydrogen bond (HB) interruption properties. ΔG(0) with the GB models is shown to correlate strongly to 2(D-1)/(2D+1) (R(2) ∼ 0.90) in line with the Onsager reaction field ( Onsager J. Am. Chem. Soc. 1936 , 58 , 1486 - 1493 ) but to be very sensitive to D (D < 10) as well. Both high-dielectric environments where hydrogen bonds are of interest and low-dielectric media such as protein binding pockets and membrane interiors therefore need to be considered with caution in GB-based calculations. Finally, a literature analysis of Gibbs energy of solvation of small molecules in organic liquids shows that the Onsager relation does not hold for real molecules since the correlation between ΔG(0) and 2(D-1)/(2D+1) is low for most solutes. Interestingly, explicit solvent calculations of the solvation free energy ( Zhang et al. J. Chem. Inf. Model . 2015 , 55 , 1192 - 1201 ) reproduce the weak

  20. SOLVENT EXTRACTION OF URANIUM VALUES

    DOEpatents

    Feder, H.M.; Ader, M.; Ross, L.E.

    1959-02-01

    A process is presented for extracting uranium salt from aqueous acidic solutions by organic solvent extraction. It consists in contacting the uranium bearing solution with a water immiscible dialkylacetamide having at least 8 carbon atoms in the molecule. Mentioned as a preferred extractant is dibutylacetamide. The organic solvent is usually used with a diluent such as kerosene or CCl/sub 4/.

  1. Supercritical multicomponent solvent coal extraction

    NASA Technical Reports Server (NTRS)

    Corcoran, W. H.; Fong, W. S.; Pichaichanarong, P.; Chan, P. C. F.; Lawson, D. D. (Inventor)

    1983-01-01

    The yield of organic extract from the supercritical extraction of coal with larger diameter organic solvents such as toluene is increased by use of a minor amount of from 0.1 to 10% by weight of a second solvent such as methanol having a molecular diameter significantly smaller than the average pore diameter of the coal.

  2. Solvent changeouts without plant shutdown

    SciTech Connect

    Vickery, D.J.; Campbell, S.W. )

    1988-01-01

    For reasons of greater selectivity, lower regeneration energy requirements, reduced corrosivity and possible greater amine stability, MDEA continues to replace DEA in numerous selective H/sub 2/S removal applications. Solvent changeouts from DEA to MDEA often require no equipment modification, yet they are generally achieved by shutting down the plant, draining the old solvent, cleaning, and finally recharging with MDEA. However, in at least one plant, solvent changeout was done on the fly simply by periodically making up normal DEA losses with MDEA until the plant was finally operating on MDEA alone. Gradual solvent changeouts have the advantages of no lost production, no disposal problems with the environmentally-hazardous old solvent, no use and subsequent disposal of cleaning agents, and no additional manpower requirements. An advanced flowsheet simulation capability can suggest when such a procedure is feasible and, when it is, plant simulation can help to ensure that the solvent changeout is done reliably and with no production or cost penalties. GASPLANT-PLUS(TM) is currently the only commercial simulator having formulated solvent (mixed amine) capabilities within a fully flexible flowsheeting environment. After highlighting its technical foundations, they will compare GASPLANT-PLUS predictions with some commercial plant data and, through examples, they will show how solvent changeouts can be done gradually, without plant shutdown.

  3. Extraordinary aluminum coordination in a novel homometallic double complex salt.

    PubMed

    Mandai, Toshihiko; Masu, Hyuma; Johansson, Patrik

    2015-07-01

    We have characterized a novel aluminum-based homometallic double complex salt, incorporating discrete octa-coordinated cationic [Al(G3)2](3+) and hexa-coordinated anionic [Al(TfO)4(OH)2](3-) complexes (G3 = triglyme, TfO = trifluoromethanesulfonate). X-ray crystallography, Raman spectra, and DFT calculations demonstrate extraordinary weak Al(3+) coordination in [Al(G3)2](3+). PMID:26024493

  4. Solvent degradation products in nuclear fuel processing solvents

    SciTech Connect

    Shook, H.E. Jr.

    1988-06-01

    The Savannah River Plant uses a modified Purex process to recover enriched uranium and separate fission products. This process uses 7.5% tri-n-butyl phosphate (TBP) dissolved in normal paraffin hydrocarbons for the solvent extraction of a nitric acid solution containing the materials to be separated. Periodic problems in product decontamination result from solvent degradation. A study to improve process efficiency has identified certain solvent degradation products and suggested mitigation measures. Undecanoic acid, lauric acid, and tridecanoic acid were tentatively identified as diluent degradation products in recycle solvent. These long-chain organic acids affect phase separation and lead to low decontamination factors. Solid phase extraction (SPE) was used to concentrate the organic acids in solvent prior to analysis by high performance liquid chromatography (HPLC). SPE and HPLC methods were optimized in this work for analysis of decanoic acid, undecanoic acid, and lauric acid in solvent. Accelerated solvent degradation studies with 7.5% TBP in normal paraffin hydrocarbons showed that long-chain organic acids and long-chain alkyl butyl phosphoric acids are formed by reactions with nitric acid. Degradation of both tributyl phosphate and hydrocarbon can be minimized with purified normal paraffin replacing the standard grade presently used. 12 refs., 1 fig., 3 tabs.

  5. COMPUTER AIDED SOLVENT DESIGN FOR THE ENVIRONMENT

    EPA Science Inventory

    Solvent substitution is an effective and useful means of eliminating the use of harmful solvents, but finding substitute solvents which are less harmful and as effective as currently used solvents presents significant difficulties. Solvent substitution is a form of reverse engin...

  6. A structurally flexible triazolate-based metal-organic framework featuring coordinatively unsaturated copper(i) sites.

    PubMed

    Schmieder, P; Denysenko, D; Grzywa, M; Magdysyuk, O; Volkmer, D

    2016-09-21

    The novel metal-organic framework CFA-8 (Coordination Framework Augsburg University-8), [Cu2(tqpt)], containing the organic linker H2-tqpt {H2-tqpt = 6,6,14,14-tetramethyl-6,14-dihydroquinoxalino[2,3-b]phenazinebis-triazole}, has been synthesized. Reaction of H2-tqpt and anhydrous CuCl2 in N,N-dimethylacetamide (DMA) yields CFA-8 as orange crystals with lenticular shape. This framework shows a reversible breathing effect and is robust upon solvent removal. It has been characterized by single-crystal and powder X-ray diffraction, TGA, IR spectroscopy and gas sorption measurements. CO adsorption isotherms show that Cu(i) sites in this framework are able to bind carbon monoxide forming a weak complex which has been additionally characterized by IR spectroscopy and synchrotron powder X-ray diffraction measurements. PMID:27513160

  7. Complete Series of Alkali-Metal M(BH3NH2BH2NH2BH3) Hydrogen-Storage Salts Accessed via Metathesis in Organic Solvents.

    PubMed

    Owarzany, Rafał; Fijalkowski, Karol J; Jaroń, Tomasz; Leszczyński, Piotr J; Dobrzycki, Łukasz; Cyrański, Michał K; Grochala, Wojciech

    2016-01-01

    We report a new efficient way of synthesizing high-purity hydrogen-rich M(BH3NH2BH2NH2BH3) salts (M = Li, Na, K, Rb, Cs). The solvent-mediated metathetic synthesis applied here uses precursors containing bulky organic cations and weakly coordinating anions. The applicability of this method permits the entire series of alkali-metal M(BH3NH2BH2NH2BH3) salts (M = Li, Na, K, Rb, Cs) to be obtained, thus enabling their comparative analysis in terms of crystal structures and hydrogen-storage properties. A novel polymorphic form of Verkade's base (C18H39N4PH)(BH3NH2BH2NH2BH3) precursor was also characterized structurally. For all compounds, we present a comprehensive structural, spectroscopic, and thermogravimetric characterization (PXRD, NMR, FTIR, Raman, and TGA/DSC/MS).

  8. A smooth and differentiable bulk-solvent model for macromolecular diffraction

    SciTech Connect

    Fenn, T. D.; Schnieders, M. J.; Brunger, A. T.

    2010-09-01

    A new method for modeling the bulk solvent in macromolecular diffraction data based on Babinet’s principle is presented. The proposed models offer the advantage of differentiability with respect to atomic coordinates. Inclusion of low-resolution data in macromolecular crystallography requires a model for the bulk solvent. Previous methods have used a binary mask to accomplish this, which has proven to be very effective, but the mask is discontinuous at the solute–solvent boundary (i.e. the mask value jumps from zero to one) and is not differentiable with respect to atomic parameters. Here, two algorithms are introduced for computing bulk-solvent models using either a polynomial switch or a smoothly thresholded product of Gaussians, and both models are shown to be efficient and differentiable with respect to atomic coordinates. These alternative bulk-solvent models offer algorithmic improvements, while showing similar agreement of the model with the observed amplitudes relative to the binary model as monitored using R, R{sub free} and differences between experimental and model phases. As with the standard solvent models, the alternative models improve the agreement primarily with lower resolution (>6 Å) data versus no bulk solvent. The models are easily implemented into crystallographic software packages and can be used as a general method for bulk-solvent correction in macromolecular crystallography.

  9. Solvent viscosity dependence for enzymatic reactions

    NASA Astrophysics Data System (ADS)

    Sitnitsky, A. E.

    2008-09-01

    A mechanism for relationship of solvent viscosity with reaction rate constant at enzyme action is suggested. It is based on fluctuations of electric field in enzyme active site produced by thermally equilibrium rocking (crankshaft motion) of the rigid plane (in which the dipole moment ≈3.6 D lies) of a favourably located and oriented peptide group (or may be a few of them). Thus the rocking of the plane leads to fluctuations of the electric field of the dipole moment. These fluctuations can interact with the reaction coordinate because the latter in its turn has transition dipole moment due to separation of charges at movement of the reacting system along it. The rocking of the plane of the peptide group is sensitive to the microviscosity of its environment in protein interior and the latter is a function of the solvent viscosity. Thus we obtain an additional factor of interrelationship for these characteristics with the reaction rate constant. We argue that due to the properties of the crankshaft motion the frequency spectrum of the electric field fluctuations has a sharp resonance peak at some frequency and the corresponding Fourier mode can be approximated as oscillations. We employ a known result from the theory of thermally activated escape with periodic driving to obtain the reaction rate constant and argue that it yields reliable description of the pre-exponent where the dependence on solvent viscosity manifests itself. The suggested mechanism is shown to grasp the main feature of this dependence known from the experiment and satisfactorily yields the upper limit of the fractional index of a power in it.

  10. Experimental investigations of weak definite and weak indefinite noun phrases

    PubMed Central

    Klein, Natalie M.; Gegg-Harrison, Whitney M.; Carlson, Greg N.; Tanenhaus, Michael K.

    2013-01-01

    Definite noun phrases typically refer to entities that are uniquely identifiable in the speaker and addressee’s common ground. Some definite noun phrases (e.g. the hospital in Mary had to go the hospital and John did too) seem to violate this uniqueness constraint. We report six experiments that were motivated by the hypothesis that these “weak definite” interpretations arise in “incorporated” constructions. Experiments 1-3 compared nouns that seem to allow for a weak definite interpretation (e.g. hospital, bank, bus, radio) with those that do not (e.g. farm, concert, car, book). Experiments 1 and 2 used an instruction-following task and picture-judgment task, respectively, to demonstrate that a weak definite need not uniquely refer. In Experiment 3 participants imagined scenarios described by sentences such as The Federal Express driver had to go to the hospital/farm. The imagined scenarios following weak definite noun phrases were more likely to include conventional activities associated with the object, whereas following regular nouns, participants were more likely to imagine scenarios that included typical activities associated with the subject; similar effects were observed with weak indefinites. Experiment 4 found that object-related activities were reduced when the same subject and object were used with a verb that does not license weak definite interpretations. In Experiment 5, a science fiction story introduced an artificial lexicon for novel concepts. Novel nouns that shared conceptual properties with English weak definite nouns were more likely to allow weak reference in a judgment task. Experiment 6 demonstrated that familiarity for definite articles and anti- familiarity for indefinite articles applies to the activity associated with the noun, consistent with predictions made by the incorporation analysis. PMID:23685208

  11. EXPERIENCES IN DESIGNING SOLVENTS FOR THE ENVIRONMENT

    EPA Science Inventory

    To meet the great need of replacing many harmful solvents commonly used by industry and the public with environmentally benign substitute solvents, the PARIS II solvent design software has been developed. Although the difficulty of successfully finding replacements increases with...

  12. Swelling of lignites in organic solvents

    SciTech Connect

    R.G. Makitra; D.V. Bryk

    2008-10-15

    Data on the swelling of Turkish lignites can be summarized using linear multiparameter equations that take into account various properties of solvents. Factors responsible for the amounts of absorbed solvents are the basicity and cohesion energy density of the solvents.

  13. Acetone-based cellulose solvent.

    PubMed

    Kostag, Marc; Liebert, Tim; Heinze, Thomas

    2014-08-01

    Acetone containing tetraalkylammonium chloride is found to be an efficient solvent for cellulose. The addition of an amount of 10 mol% (based on acetone) of well-soluble salt triethyloctylammonium chloride (Et3 OctN Cl) adjusts the solvent's properties (increases the polarity) to promote cellulose dissolution. Cellulose solutions in acetone/Et3 OctN Cl have the lowest viscosity reported for comparable aprotic solutions making it a promising system for shaping processes and homogeneous chemical modification of the biopolymer. Recovery of the polymer and recycling of the solvent components can be easily achieved.

  14. Caustic-Side Solvent Extraction Solvent-Composition Recommendation

    SciTech Connect

    Klatt, L.N.

    2002-05-09

    The U.S. Department of Energy has selected caustic-side solvent extraction as the preferred cesium removal technology for the treatment of high-level waste stored at the Savannah River Site. Data for the solubility of the extractant, calix[4]arene-bis(tert-octyl benzo-crown-6), acquired and reported for the Salt Processing Program down-select decision, showed the original solvent composition to be supersaturated with respect to the extractant. Although solvent samples have been observed for approximately 1 year without any solids formation, work was completed to define a new solvent composition that was thermodynamically stable with respect to solids formation and to expand the operating temperature with respect to third-phase formation. Chemical and physical data as a function of solvent component concentrations were collected. The data included calix[4]arene-bis(tert-octyl benzo-crown-6) solubility; cesium distribution ratio under extraction, scrub, and strip conditions; flow sheet robustness; temperature range of third-phase formation; dispersion numbers for the solvent against waste simulant, scrub and strip acids, and sodium hydroxide wash solutions; solvent density; viscosity; and surface and interfacial tension. These data were mapped against a set of predefined performance criteria. The composition of 0.007 M calix[4]arene-bis(tert-octyl benzo-crown-6), 0.75 M 1-(2,2,3,3-tetrafluoropropoxy)-3-(4-sec-butylphenoxy)-2-propanol, and 0.003 M tri-n-octylamine in the diluent Isopar{reg_sign} L provided the best match between the measured properties and the performance criteria. Therefore, it is recommended as the new baseline solvent composition.

  15. Acquired intolerance to organic solvents and results of vestibular testing

    SciTech Connect

    Gyntelberg, F.; Vesterhauge, S.; Fog, P.; Isager, H.; Zillstorff, K.

    1986-01-01

    Among 160 consecutive patients referred to the Clinic of Occupational Medicine, Rigshospitalet, for symptoms connected with exposure to organic solvents, 20 exhibited symptoms of acquired intolerance to minor amounts of organic solvents. Later, an additional 30 consecutive patients with symptoms of acquired intolerance were included, yielding a total of 43 men and 7 women. The characteristics of the clinical syndrome described are complaints of dizziness, nausea, and weakness after exposure to minimal solvent vapor concentrations. After having tolerated long-term occupational exposure to moderate or high air concentrations of various organic solvents, the patients became intolerant within a short period of time. Since dizziness was a frequent complaint, we tried to obtain a measure of the patients' complaints using vestibular tests. As a diagnostic test the combined vestibular tests had a sensitivity of 0.55 and a specificity of 0.87. No differences between patients with and without intolerance could be detected by the vestibular tests used. We conclude that acquired intolerance to organic solvents is a new but characteristic and easily recognizable syndrome, often with severe consequences for the patient's working ability.

  16. Resisting Weakness of the Will

    PubMed Central

    Levy, Neil

    2012-01-01

    I develop an account of weakness of the will that is driven by experimental evidence from cognitive and social psychology. I will argue that this account demonstrates that there is no such thing as weakness of the will: no psychological kind corresponds to it. Instead, weakness of the will ought to be understood as depletion of System II resources. Neither the explanatory purposes of psychology nor our practical purposes as agents are well-served by retaining the concept. I therefore suggest that we ought to jettison it, in favour of the vocabulary and concepts of cognitive psychology. PMID:22984298

  17. Weak-shock reflection factors

    SciTech Connect

    Reichenbach, H.; Kuhl, A.L.

    1993-09-07

    The purpose of this paper is to compare reflection factors for weak shocks from various surfaces, and to focus attention on some unsolved questions. Three different cases are considered: square-wave planar shock reflection from wedges; square-wave planar shock reflection from cylinders; and spherical blast wave reflection from a planar surface. We restrict ourselves to weak shocks. Shocks with a Mach number of M{sub O} < 1.56 in air or with an overpressure of {Delta}{sub PI} < 25 psi (1.66 bar) under normal ambient conditions are called weak.

  18. Divalent Cu, Cd, and Pb Biosorption in Mixed Solvents

    PubMed Central

    Al-Qunaibit, M. H.

    2009-01-01

    Dead dried Chlorella vulgaris was studied in terms of its performance in binding divalent copper, cadmium, and lead ions from their aqueous or 50% v/v methanol, ethanol, and acetone solutions. The percentage uptake of cadmium ions exhibited a general decrease with decrease in dielectric constant values, while that of copper and lead ions showed a general decrease with increase in donor numbers. Uptake percentage becomes less sensitive to solvent properties the larger the atomic radius of the biosorbed ion, and uptake of copper was the most affected. FT-IR analyses revealed stability of the biomass in mixed solvents and a shift in vibrations of amide(I) and (II), carboxylate, glucose ring, and metal oxygen upon metal binding in all media. ΔνCOO values (59–69 cm−1) confirmed bidentate metal coordination to carboxylate ligands. The value of νasCOO increased slightly upon Cu, Cd, and Pb biosorption from aqueous solutions indicating lowering of symmetry, while a general decrease was noticed in mixed solvents pointing to the opposite. M–O stretching frequencies increased unexpectedly with increase in atomic mass as a result of solvent effect on the nature of binding sites. Lowering polarity of the solvent permits variations in metal-alga bonds strengths; the smaller the metal ion, the more affected. PMID:19688108

  19. Movement and Coordination

    MedlinePlus

    ... will seem to be continually on the go—running, kicking, climbing, jumping. His attention span, which was ... his coordination. In the months ahead, your child’s running will become smoother and more coordinated. He’ll ...

  20. Coordination Chemistry Dictates the Structural Defects in Lead Halide Perovskites.

    PubMed

    Rahimnejad, Sara; Kovalenko, Alexander; Forés, Sergio Martí; Aranda, Clara; Guerrero, Antonio

    2016-09-19

    We show the influence of species present in precursor solution during formation of lead halide perovskite materials on the structural defects of the films. The coordination of lead by competing solvent molecules and iodide ions dictate the type of complexes present in the films. Depending on the processing conditions all PbIS5 (+) , PbI2 S4, PbI3 S3 (-) , PbI4 S2 (2-) , PbI5 S2 (3-) , PbI6 (4-) and 1D (Pb2 I4 )n chains are observed by absorption measurements. Different parameters are studied such as polarity of the solvent, concentration of iodide ions, concentration of solvent molecules and temperature. It is concluded that strongly coordinating solvents will preferentially form species with a low number of iodide ions and less coordinative solvents generate high concentration of PbI6 (-) . We furthermore propose that all these plumbate ions may act as structural defects determining electronic properties of the photovoltaic films.

  1. Weak interactions and presupernova evolution

    SciTech Connect

    Aufderheide, M.B. State Univ. of New York . Dept. of Physics)

    1991-02-19

    The role of weak interactions, particularly electron capture and {beta}{sup {minus}} decay, in presupernova evolution is discussed. The present uncertainty in these rates is examined and the possibility of improving the situation is addressed. 12 refs., 4 figs.

  2. Analysis Coordinator Report

    NASA Technical Reports Server (NTRS)

    Nothnagel, A.

    2013-01-01

    We present the IVS analysis coordination issues of 2012. The IVS Analysis Coordinator is responsible for generating and disseminating the official IVS products. This requires consistency of the input data by strict adherence to models and conventions. The term of the current IVS Analysis Coordinator will end on February 28, 2013.

  3. Processing Coordination Ambiguity

    ERIC Educational Resources Information Center

    Engelhardt, Paul E.; Ferreira, Fernanda

    2010-01-01

    We examined temporarily ambiguous coordination structures such as "put the butter in the bowl and the pan on the towel." Minimal Attachment predicts that the ambiguous noun phrase "the pan" will be interpreted as a noun-phrase coordination structure because it is syntactically simpler than clausal coordination. Constraint-based theories assume…

  4. Literacy Coordinators' Handbook.

    ERIC Educational Resources Information Center

    Department for Education and Skills, London (England).

    This handbook is designed to provide support for England's National Literacy Strategy's Literacy Coordinators leading and coordinating literacy across the school. The handbook is designed as a working document and will contain additional materials, LEA (local education authorities) guidance, and additional papers which Coordinators may choose to…

  5. SOLV-DB: Solvents Data

    DOE Data Explorer

    SOLV-DB provides a specialized mix of information on commercially available solvents. The development of the database was funded under the Strategic Environmental Research and Development Program (SERDP) with funds from EPA and DOE's Office of Industrial Technologies in EE. The information includes: • Health and safety considerations involved in choosing and using solvents • Chemical and physical data affecting the suitability of a particular solvent for a wide range of potential applications • Regulatory responsibilities, including exposure and effluent limits, hazard classification status with respect to several key statutes, and selected reporting requirements • Environmental fate data, to indicate whether a solvent is likely to break down or persist in air or water, and what types of waste treatment techniques may apply to it • CAS numbers (from Chemical Abstracts Service) and Sax Numbers (from Sax, et.al., Dangerous Properties of Industrial Materials) Supplier Information See help information at http://solvdb.ncms.org/welcome.htm (Specialized Interface)

  6. ON-SITE SOLVENT RECOVERY

    EPA Science Inventory

    This study evaluated the product quality, waste reduction/pollution prevention, and economic aspects of three technologies for onsite solvent recovery: atmospheric batch distillation, vacuum heat-pump distillation, and low-emission vapor degreasing. The atmospheric and vacuum ...

  7. Precision Metrology Using Weak Measurements

    NASA Astrophysics Data System (ADS)

    Zhang, Lijian; Datta, Animesh; Walmsley, Ian A.

    2015-05-01

    Weak values and measurements have been proposed as a means to achieve dramatic enhancements in metrology based on the greatly increased range of possible measurement outcomes. Unfortunately, the very large values of measurement outcomes occur with highly suppressed probabilities. This raises three vital questions in weak-measurement-based metrology. Namely, (Q1) Does postselection enhance the measurement precision? (Q2) Does weak measurement offer better precision than strong measurement? (Q3) Is it possible to beat the standard quantum limit or to achieve the Heisenberg limit with weak measurement using only classical resources? We analyze these questions for two prototypical, and generic, measurement protocols and show that while the answers to the first two questions are negative for both protocols, the answer to the last is affirmative for measurements with phase-space interactions, and negative for configuration space interactions. Our results, particularly the ability of weak measurements to perform at par with strong measurements in some cases, are instructive for the design of weak-measurement-based protocols for quantum metrology.

  8. Ferromagnetic ordering of -[Sm(iii)-radical]n- coordination polymers.

    PubMed

    Fatila, Elisabeth M; Maahs, Adam C; Mills, Michelle B; Rouzières, Mathieu; Soldatov, Dmitriy V; Clérac, Rodolphe; Preuss, Kathryn E

    2016-04-01

    [Sm(hfac)3(boaDTDA)]n is the first coordination compound of a thiazyl-based neutral radical ligand to exhibit ferromagnetic ordering; TC = 3 K. The [Sm(iii)-radical]n species is soluble in common organic solvents and can be sublimed quantitatively. A McConnell I mechanism is implicated in local exchange pathways that contribute to cooperative magnetic properties.

  9. Water as a solvent for life

    NASA Astrophysics Data System (ADS)

    Pohorille, Andrew

    2015-08-01

    “Follow the water” is our basic strategy in searching for life in the universe. The universality of water as the solvent for living systems is usually justified by arguing that water supports the rich organic chemistry that seeds life, but alternative chemistries are possible in other organic solvents. Here, other, essential criteria for life that have not been sufficiently considered so far, will be discussed.Life is based on non-covalent interactions. They might be either specific (enzyme-substrate interactions, selective ion transport) or nonspecific (lipid-lipid or lipid-protein interactions). Their strength needs to be properly tuned, and this is mediated by the solvent. If interactions are too weak, there might be undesired response to natural fluctuations of physical and chemical parameters. If they are too strong it could impede kinetics and energetics of cellular processes. Thus, the solvent must allow for balancing these interactions, which provides strong constraints for life.Water exhibits a remarkable trait that it promotes both solvophobic and solvophilic interactions. Solvophobic (hydrophobic in the case of water) interactions are necessary for self-organization of matter. They are responsible, among others, for the formation of membranes and protein folding. The diversity of structures supported by hydrophobic interactions is the hallmark of terrestrial life responsible for its diversity, evolution and the ability to survive environmental changes. Solvophilic interactions, in turn, are needed to ensure solubility of polar species. Water offers a large temperature domain of stable liquid and the characteristic hydrophobic effects are a consequence of the temperature insensitivity of essential properties of its liquid state. Water, however, might not be the only liquid with these properties. Properties of water and other pure liquids or their mixtures that have a high dielectric constant and simultaneously support self-organization will be

  10. Conformational transitions of weak polyacids grafted to nanoparticles

    NASA Astrophysics Data System (ADS)

    Barr, S. A.; Panagiotopoulos, A. Z.

    2012-10-01

    The charge distribution on polyelectrolytes is a key factor, which controls their conformation and interactions. In weak polyelectrolytes, this distribution is determined by a number of factors, including the solvent conditions and local environment. In this work, we investigate charge distributions of chains end-grafted on a spherical nanoparticle in a salt solution, using grand canonical titration Monte Carlo simulations of a coarse-grained polymer model. In this approach, the ionization state of each polymer bead fluctuates based on the dissociation constant, pH of the solution, and interactions with other particles in the system. We determine charge and polymer conformations as functions of the pH and solvent quality. We compare the results to a fixed charge model and also investigate the role of grafting density and the effect of curvature on the film morphologies.

  11. Nonadiabatic dynamics of electron transfer in solution: Explicit and implicit solvent treatments that include multiple relaxation time scales

    SciTech Connect

    Schwerdtfeger, Christine A.; Soudackov, Alexander V.; Hammes-Schiffer, Sharon

    2014-01-21

    The development of efficient theoretical methods for describing electron transfer (ET) reactions in condensed phases is important for a variety of chemical and biological applications. Previously, dynamical dielectric continuum theory was used to derive Langevin equations for a single collective solvent coordinate describing ET in a polar solvent. In this theory, the parameters are directly related to the physical properties of the system and can be determined from experimental data or explicit molecular dynamics simulations. Herein, we combine these Langevin equations with surface hopping nonadiabatic dynamics methods to calculate the rate constants for thermal ET reactions in polar solvents for a wide range of electronic couplings and reaction free energies. Comparison of explicit and implicit solvent calculations illustrates that the mapping from explicit to implicit solvent models is valid even for solvents exhibiting complex relaxation behavior with multiple relaxation time scales and a short-time inertial response. The rate constants calculated for implicit solvent models with a single solvent relaxation time scale corresponding to water, acetonitrile, and methanol agree well with analytical theories in the Golden rule and solvent-controlled regimes, as well as in the intermediate regime. The implicit solvent models with two relaxation time scales are in qualitative agreement with the analytical theories but quantitatively overestimate the rate constants compared to these theories. Analysis of these simulations elucidates the importance of multiple relaxation time scales and the inertial component of the solvent response, as well as potential shortcomings of the analytical theories based on single time scale solvent relaxation models. This implicit solvent approach will enable the simulation of a wide range of ET reactions via the stochastic dynamics of a single collective solvent coordinate with parameters that are relevant to experimentally accessible

  12. Nonadiabatic dynamics of electron transfer in solution: Explicit and implicit solvent treatments that include multiple relaxation time scales

    NASA Astrophysics Data System (ADS)

    Schwerdtfeger, Christine A.; Soudackov, Alexander V.; Hammes-Schiffer, Sharon

    2014-01-01

    The development of efficient theoretical methods for describing electron transfer (ET) reactions in condensed phases is important for a variety of chemical and biological applications. Previously, dynamical dielectric continuum theory was used to derive Langevin equations for a single collective solvent coordinate describing ET in a polar solvent. In this theory, the parameters are directly related to the physical properties of the system and can be determined from experimental data or explicit molecular dynamics simulations. Herein, we combine these Langevin equations with surface hopping nonadiabatic dynamics methods to calculate the rate constants for thermal ET reactions in polar solvents for a wide range of electronic couplings and reaction free energies. Comparison of explicit and implicit solvent calculations illustrates that the mapping from explicit to implicit solvent models is valid even for solvents exhibiting complex relaxation behavior with multiple relaxation time scales and a short-time inertial response. The rate constants calculated for implicit solvent models with a single solvent relaxation time scale corresponding to water, acetonitrile, and methanol agree well with analytical theories in the Golden rule and solvent-controlled regimes, as well as in the intermediate regime. The implicit solvent models with two relaxation time scales are in qualitative agreement with the analytical theories but quantitatively overestimate the rate constants compared to these theories. Analysis of these simulations elucidates the importance of multiple relaxation time scales and the inertial component of the solvent response, as well as potential shortcomings of the analytical theories based on single time scale solvent relaxation models. This implicit solvent approach will enable the simulation of a wide range of ET reactions via the stochastic dynamics of a single collective solvent coordinate with parameters that are relevant to experimentally accessible

  13. Solvents and Parkinson disease: A systematic review of toxicological and epidemiological evidence

    PubMed Central

    Lock, Edward A.; Zhang, Jing; Checkoway, Harvey

    2013-01-01

    Parkinson disease (PD) is a debilitating neurodegenerative motor disorder, with its motor symptoms largely attributable to loss of dopaminergic neurons in the substantia nigra. The causes of PD remain poorly understood, although environmental toxicants may play etiologic roles. Solvents are widespread neurotoxicants present in the workplace and ambient environment. Case reports of parkinsonism, including PD, have been associated with exposures to various solvents, most notably trichloroethylene (TCE). Animal toxicology studies have been conducted on various organic solvents, with some, including TCE, demonstrating potential for inducing nigral system damage. However, a confirmed animal model of solvent-induced PD has not been developed. Numerous epidemiologic studies have investigated potential links between solvents and PD, yielding mostly null or weak associations. An exception is a recent study of twins indicating possible etiologic relations with TCE and other chlorinated solvents, although findings were based on small numbers, and dose–response gradients were not observed. At present, there is no consistent evidence from either the toxicological or epidemiologic perspective that any specific solvent or class of solvents is a cause of PD. Future toxicological research that addresses mechanisms of nigral damage from TCE and its metabolites, with exposure routes and doses relevant to human exposures, is recommended. Improvements in epidemiologic research, especially with regard to quantitative characterization of long-term exposures to specific solvents, are needed to advance scientific knowledge on this topic. PMID:23220449

  14. Movement coordination during conversation.

    PubMed

    Latif, Nida; Barbosa, Adriano V; Vatikiotis-Bateson, Eric; Vatiokiotis-Bateson, Eric; Castelhano, Monica S; Munhall, K G

    2014-01-01

    Behavioral coordination and synchrony contribute to a common biological mechanism that maintains communication, cooperation and bonding within many social species, such as primates and birds. Similarly, human language and social systems may also be attuned to coordination to facilitate communication and the formation of relationships. Gross similarities in movement patterns and convergence in the acoustic properties of speech have already been demonstrated between interacting individuals. In the present studies, we investigated how coordinated movements contribute to observers' perception of affiliation (friends vs. strangers) between two conversing individuals. We used novel computational methods to quantify motor coordination and demonstrated that individuals familiar with each other coordinated their movements more frequently. Observers used coordination to judge affiliation between conversing pairs but only when the perceptual stimuli were restricted to head and face regions. These results suggest that observed movement coordination in humans might contribute to perceptual decisions based on availability of information to perceivers. PMID:25119189

  15. Movement Coordination during Conversation

    PubMed Central

    Latif, Nida; Barbosa, Adriano V.; Vatiokiotis-Bateson, Eric; Castelhano, Monica S.; Munhall, K. G.

    2014-01-01

    Behavioral coordination and synchrony contribute to a common biological mechanism that maintains communication, cooperation and bonding within many social species, such as primates and birds. Similarly, human language and social systems may also be attuned to coordination to facilitate communication and the formation of relationships. Gross similarities in movement patterns and convergence in the acoustic properties of speech have already been demonstrated between interacting individuals. In the present studies, we investigated how coordinated movements contribute to observers’ perception of affiliation (friends vs. strangers) between two conversing individuals. We used novel computational methods to quantify motor coordination and demonstrated that individuals familiar with each other coordinated their movements more frequently. Observers used coordination to judge affiliation between conversing pairs but only when the perceptual stimuli were restricted to head and face regions. These results suggest that observed movement coordination in humans might contribute to perceptual decisions based on availability of information to perceivers. PMID:25119189

  16. Alternative solvents for improving the greenness of normal phase liquid chromatography of lipid classes.

    PubMed

    Prache, Nolwenn; Abreu, Sonia; Sassiat, Patrick; Thiébaut, Didier; Chaminade, Pierre

    2016-09-16

    An evaluation of solvents alternative to n-heptane (d-limonene and hexamethyldisiloxane) and chloroform (cyclopentyl methyl ether, 2-methyltetrahydrofuran and isopentyl acetate) was developed for lipid classes separation of non-polar cholesteryl ester to highly polar phospholipids by high-performance liquid chromatography on bare silica stationary phase and evaporative light-scattering detection. Screening of alternative solvents was used to estimate their compatibility with liquid chromatography and evaporative light-scattering detection and to evaluate their chromatographic selectivity. This work shows that n-heptane can be advantageously replaced by hexamethyldisiloxane. An increase of non-polar lipids retention is observed with hexamethyldisiloxane as weak solvent. Chloroform, which is largely used for lipid analysis, might be replaced efficaciously by cyclopentyl methyl ether, 2-methyltetrahydrofuran or isopentyl acetate. Aside from offering a different selectivity, the gradients composed by one or both alternative solvents gave efficient and comparable or even better separations than those obtained with conventional solvents. PMID:27554026

  17. Dry layer formation? Solvent polarity at hydrophobic solid-liquid surfaces

    NASA Astrophysics Data System (ADS)

    Walker, Robert; Zhang, Xiaoyi; Esenturk, Okan

    2002-03-01

    From low-wear, "friction-free" materials to reverse phase chromatography columns to specific protein domains, hydrophobic surfaces are ubiquitous in physics, chemistry and biology. Our efforts to understand how hydrophobic surfaces influence the solvating properties of an adjacent solvent have led us to investigate solvent polarity at a number of weakly associating, solid-liquid interfaces. Second-order nonlinear optical spectroscopy enables experiments to probe the solvent-sensitive excitation energies of adsorbed probe molecules. Comparisons to probe behavior in bulk solution allow us to infer how hydrophobic surfaces have altered properties inside of the solute cavity. Boundaries formed between hydrophobic surfaces and associating or hydrogen bonding solvents show significantly reduced solvent polarity, consistent with proposed models of dry-layer formation. Polar, aprotic liquid-hydrophobic solid interfaces show no evidence of this effect. We can understand this behavior based on the relative imbalance in forces between the solid and liquid phases.

  18. Solvent/Non-Solvent Sintering To Make Microsphere Scaffolds

    NASA Technical Reports Server (NTRS)

    Laurencin, Cato T.; Brown, Justin L.; Nair, Lakshmi

    2011-01-01

    A solvent/non-solvent sintering technique has been devised for joining polymeric microspheres to make porous matrices for use as drug-delivery devices or scaffolds that could be seeded with cells for growing tissues. Unlike traditional sintering at elevated temperature and pressure, this technique is practiced at room temperature and pressure and, therefore, does not cause thermal degradation of any drug, protein, or other biochemical with which the microspheres might be loaded to impart properties desired in a specific application. Also, properties of scaffolds made by this technique are more reproducible than are properties of comparable scaffolds made by traditional sintering. The technique involves the use of two miscible organic liquids: one that is and one that is not a solvent for the affected polymer. The polymeric microspheres are placed in a mold having the size and shape of the desired scaffold, then the solvent/non-solvent mixture is poured into the mold to fill the void volume between the microspheres, then the liquid mixture is allowed to evaporate. Some of the properties of the resulting scaffold can be tailored through choice of the proportions of the liquids and the diameter of the microspheres.

  19. Computational comparison of oxidation stability: Solvent/salt monomers vs solvent-solvent/salt pairs

    NASA Astrophysics Data System (ADS)

    Kim, Dong Young; Park, Min Sik; Lim, Younhee; Kang, Yoon-Sok; Park, Jin-Hwan; Doo, Seok-Gwang

    2015-08-01

    A fundamental understanding of the anodic stabilities of electrolytes is important for the development of advanced high-voltage electrolytes. In this study, we calculated and systematically compared the oxidation stabilities of monomeric solvents and anions, and bimolecular solvent-solvent and anion-solvent systems that are considered to be high-voltage electrolyte components, using ab initio calculations. Oxidation stabilities of solvent or anion monomers without considering specific solvation molecules cannot represent experimental oxidation stabilities. The oxidation of electrolytes usually forms neutral or cationic radicals, which immediately undergo further reactions stabilizing the products. Oxidatively driven intermolecular reactions are the main reason for the lower oxidation stabilities of electrolytes compared with those of monomeric compounds. Electrolyte components such as tetramethylene sulfone (TMS), ethyl methyl sulfone (EMS), bis(oxalate)borate (BOB-), and bis(trifluoromethane)sulfonamide (TFSI-) that minimize such intermolecular chemical reactions on oxidation can maintain the oxidation stabilities of monomers. In predictions of the theoretical oxidation stabilities of electrolytes, simple comparisons of highest occupied molecular orbital energies can be misleading, even if microsolvation or bulk clusters are considered. Instead, bimolecular solvent complexes with a salt anion should be at least considered in oxidation calculations. This study provides important information on fundamental and applied aspects of the development of electrolytes.

  20. Quantum discord with weak measurements

    SciTech Connect

    Singh, Uttam Pati, Arun Kumar

    2014-04-15

    Weak measurements cause small change to quantum states, thereby opening up the possibility of new ways of manipulating and controlling quantum systems. We ask, can weak measurements reveal more quantum correlation in a composite quantum state? We prove that the weak measurement induced quantum discord, called as the “super quantum discord”, is always larger than the quantum discord captured by the strong measurement. Moreover, we prove the monotonicity of the super quantum discord as a function of the measurement strength and in the limit of strong projective measurement the super quantum discord becomes the normal quantum discord. We find that unlike the normal discord, for pure entangled states, the super quantum discord can exceed the quantum entanglement. Our results provide new insights on the nature of quantum correlation and suggest that the notion of quantum correlation is not only observer dependent but also depends on how weakly one perturbs the composite system. We illustrate the key results for pure as well as mixed entangled states. -- Highlights: •Introduced the role of weak measurements in quantifying quantum correlation. •We have introduced the notion of the super quantum discord (SQD). •For pure entangled state, we show that the SQD exceeds the entanglement entropy. •This shows that quantum correlation depends not only on observer but also on measurement strength.

  1. Weak Selection and Protein Evolution

    PubMed Central

    Akashi, Hiroshi; Osada, Naoki; Ohta, Tomoko

    2012-01-01

    The “nearly neutral” theory of molecular evolution proposes that many features of genomes arise from the interaction of three weak evolutionary forces: mutation, genetic drift, and natural selection acting at its limit of efficacy. Such forces generally have little impact on allele frequencies within populations from generation to generation but can have substantial effects on long-term evolution. The evolutionary dynamics of weakly selected mutations are highly sensitive to population size, and near neutrality was initially proposed as an adjustment to the neutral theory to account for general patterns in available protein and DNA variation data. Here, we review the motivation for the nearly neutral theory, discuss the structure of the model and its predictions, and evaluate current empirical support for interactions among weak evolutionary forces in protein evolution. Near neutrality may be a prevalent mode of evolution across a range of functional categories of mutations and taxa. However, multiple evolutionary mechanisms (including adaptive evolution, linked selection, changes in fitness-effect distributions, and weak selection) can often explain the same patterns of genome variation. Strong parameter sensitivity remains a limitation of the nearly neutral model, and we discuss concave fitness functions as a plausible underlying basis for weak selection. PMID:22964835

  2. Noncommutativity in weakly curved background by canonical methods

    SciTech Connect

    Davidovic, Lj.; Sazdovic, B.

    2011-03-15

    Using the canonical method, we investigate the Dp-brane world-volume noncommutativity in a weakly curved background. The term 'weakly curved' means that, in the leading order, the source of nonflatness is an infinitesimally small Kalb-Ramond field B{sub {mu}{nu}}, linear in coordinate, while the Ricci tensor does not contribute, being an infinitesimal of the second order. On the solution of boundary conditions, we find a simple expression for the space-time coordinates in terms of the effective coordinates and momenta. This basic relation helped us to prove that noncommutativity appears only on the world sheet boundary. The noncommutativity parameter has a standard form, but with the infinitesimally small and coordinate-dependent antisymmetric tensor B{sub {mu}{nu}}. This result coincides with that obtained on the group manifolds in the limit of the large level n of the current algebra. After quantization, the algebra of the functions on the Dp-brane world volume is represented with the Kontsevich star product instead of the Moyal one in the flat background.

  3. Coal liquefaction process with enhanced process solvent

    DOEpatents

    Givens, Edwin N.; Kang, Dohee

    1984-01-01

    In an improved coal liquefaction process, including a critical solvent deashing stage, high value product recovery is improved and enhanced process-derived solvent is provided by recycling second separator underflow in the critical solvent deashing stage to the coal slurry mix, for inclusion in the process solvent pool.

  4. New insight of coordination and extraction of uranium(VI) with N-donating ligands in room temperature ionic liquids: N,N'-diethyl-N,N'-ditolyldipicolinamide as a case study.

    PubMed

    Yuan, Li-Yong; Sun, Man; Mei, Lei; Wang, Lin; Zheng, Li-Rong; Gao, Zeng-Qiang; Zhang, Jing; Zhao, Yu-Liang; Chai, Zhi-Fang; Shi, Wei-Qun

    2015-02-16

    Room temperature ionic liquids (RTILs) represent a recent new class of solvents applied in liquid/liquid extraction based nuclear fuel reprocessing, whereas the related coordination chemistry and detailed extraction processes are still not well understood and remain of deep fundamental interest. The work herein provides a new insight of coordination and extraction of uranium(VI) with N-donating ligands, e.g., N,N'-diethyl-N,N'-ditolyldipicolinamide (EtpTDPA), in commonly used RTILs. Exploration of the extraction mechanism, speciation analyses of the extracted U(VI), and crystallographic studies of the interactions of EtpTDPA with U(VI) were performed, including the first structurally characterized UO2(EtpTDPA)2(NTf2) and UO2(EtpTDPA)2(PF6)2 compounds and a first case of crystallographic differentiation between the extracted U(VI) complexes in RTILs and in molecular solvents. It was found that in RTILs two EtpTDPA molecules coordinate with one U(VI) ion through the carbonyl and pyridine nitrogen moieties, while NTf2(-) and PF6(-) act as counterions. The absence of NO3(-) in the complexes is coincident with a cation-exchange extraction. In contrast, both the extracted species and extraction mechanisms are greatly different in dichloromethane, in which UO2(2+) coordinates in a neutral complex form with one EtpTDPA molecule and two NO3(-) cations. In addition, the complex formation in RTILs is independent of the cation exchange since incorporating UO2(NO3)2, EtpTDPA, and LiNTf2 or KPF6 in a solution also produces the same complex as that in RTILs, revealing the important roles of weakly coordinating anions on the coordination chemistry between U(VI) and EtpTDPA. These findings suggest that cation-exchange extraction mode for ILs-based extraction system probably originates from the supply of weakly coordinating anions from RTILs. Thus the coordination of uranium(VI) with extractants as well as the cation-exchange extraction mode may be potentially changed by varying the

  5. New insight of coordination and extraction of uranium(VI) with N-donating ligands in room temperature ionic liquids: N,N'-diethyl-N,N'-ditolyldipicolinamide as a case study.

    PubMed

    Yuan, Li-Yong; Sun, Man; Mei, Lei; Wang, Lin; Zheng, Li-Rong; Gao, Zeng-Qiang; Zhang, Jing; Zhao, Yu-Liang; Chai, Zhi-Fang; Shi, Wei-Qun

    2015-02-16

    Room temperature ionic liquids (RTILs) represent a recent new class of solvents applied in liquid/liquid extraction based nuclear fuel reprocessing, whereas the related coordination chemistry and detailed extraction processes are still not well understood and remain of deep fundamental interest. The work herein provides a new insight of coordination and extraction of uranium(VI) with N-donating ligands, e.g., N,N'-diethyl-N,N'-ditolyldipicolinamide (EtpTDPA), in commonly used RTILs. Exploration of the extraction mechanism, speciation analyses of the extracted U(VI), and crystallographic studies of the interactions of EtpTDPA with U(VI) were performed, including the first structurally characterized UO2(EtpTDPA)2(NTf2) and UO2(EtpTDPA)2(PF6)2 compounds and a first case of crystallographic differentiation between the extracted U(VI) complexes in RTILs and in molecular solvents. It was found that in RTILs two EtpTDPA molecules coordinate with one U(VI) ion through the carbonyl and pyridine nitrogen moieties, while NTf2(-) and PF6(-) act as counterions. The absence of NO3(-) in the complexes is coincident with a cation-exchange extraction. In contrast, both the extracted species and extraction mechanisms are greatly different in dichloromethane, in which UO2(2+) coordinates in a neutral complex form with one EtpTDPA molecule and two NO3(-) cations. In addition, the complex formation in RTILs is independent of the cation exchange since incorporating UO2(NO3)2, EtpTDPA, and LiNTf2 or KPF6 in a solution also produces the same complex as that in RTILs, revealing the important roles of weakly coordinating anions on the coordination chemistry between U(VI) and EtpTDPA. These findings suggest that cation-exchange extraction mode for ILs-based extraction system probably originates from the supply of weakly coordinating anions from RTILs. Thus the coordination of uranium(VI) with extractants as well as the cation-exchange extraction mode may be potentially changed by varying the

  6. Warping the Weak Gravity Conjecture

    NASA Astrophysics Data System (ADS)

    Kooner, Karta; Parameswaran, Susha; Zavala, Ivonne

    2016-08-01

    The Weak Gravity Conjecture, if valid, rules out simple models of Natural Inflation by restricting their axion decay constant to be sub-Planckian. We revisit stringy attempts to realise Natural Inflation, with a single open string axionic inflaton from a probe D-brane in a warped throat. We show that warped geometries can allow the requisite super-Planckian axion decay constant to be achieved, within the supergravity approximation and consistently with the Weak Gravity Conjecture. Preliminary estimates of the brane backreaction suggest that the probe approximation may be under control. However, there is a tension between large axion decay constant and high string scale, where the requisite high string scale is difficult to achieve in all attempts to realise large field inflation using perturbative string theory. We comment on the Generalized Weak Gravity Conjecture in the light of our results.

  7. State tomography via weak measurements

    PubMed Central

    Wu, Shengjun

    2013-01-01

    Recent work has revealed that the wave function of a pure state can be measured directly and that complementary knowledge of a quantum system can be obtained simultaneously by weak measurements. However, the original scheme applies only to pure states, and it is not efficient because most of the data are discarded by post-selection. Here, we propose tomography schemes for pure states and for mixed states via weak measurements, and our schemes are more efficient because we do not discard any data. Furthermore, we demonstrate that any matrix element of a general state can be directly read from an appropriate weak measurement. The density matrix (with all of its elements) represents all that is directly accessible from a general measurement. PMID:23378924

  8. Acid Base Titrations in Nonaqueous Solvents and Solvent Mixtures

    NASA Astrophysics Data System (ADS)

    Barcza, Lajos; Buvári-Barcza, Ágnes

    2003-07-01

    The acid base determination of different substances by nonaqueous titrations is highly preferred in pharmaceutical analyses since the method is quantitative, exact, and reproducible. The modern interpretation of the reactions in nonaqueous solvents started in the last century, but several inconsistencies and unsolved problems can be found in the literature. The acid base theories of Brønsted Lowry and Lewis as well as the so-called solvent theory are outlined first, then the promoting (and leveling) and the differentiating effects are discussed on the basis of the hydrogen-bond concept. Emphasis is put on the properties of formic acid and acetic anhydride since their importance is increasing.

  9. DOE solvent handbook information sheet

    SciTech Connect

    Chavez, A.A.

    1992-01-01

    Solvents and cleaners are used in the Department of Defense (DOD) and the Department of Energy-Defense Program (DOE-DP) maintenance facilities for removing wax, grease, oil, carbon, machining fluids, solder fluxes, mold releases, and other contaminants before repairing or electroplating parts. Private industry also uses cleaners and degreasers for surface preparation of various metals. Growing environmental and worker safety concerns have brought attention to these solvents and cleaners, most of which are classified as toxic. Tightening government regulations have already excluded the use of some chemicals, and restrict the use of various halogenated hydrocarbons because of their atmospheric-ozone depleting effects, as well as their cancer-related risks. As a result, a program was established to develop an efficient, easily accessible, electronic solvent utilization handbook. This is being accomplished by: (1) identifying solvents (alternatives) that are not currently restricted by government regulations for use DOE-DP facilities, and private industry, (2) evaluating their cleaning performance, (3) evaluating their corrosivity, (4) evaluating their air emissions, (5) evaluating the possibility of recycling or recovering all or portions of the alternative degreasers, (6) testing substitute solvents compatibility with non-metallic materials, (7) inputting all of the data gathered (including previous biodegradability information) into a database, and (8) developing a methodology for efficient, widespread access to the data base information system.

  10. DOE solvent handbook information sheet

    SciTech Connect

    Chavez, A.A.

    1992-05-01

    Solvents and cleaners are used in the Department of Defense (DOD) and the Department of Energy-Defense Program (DOE-DP) maintenance facilities for removing wax, grease, oil, carbon, machining fluids, solder fluxes, mold releases, and other contaminants before repairing or electroplating parts. Private industry also uses cleaners and degreasers for surface preparation of various metals. Growing environmental and worker safety concerns have brought attention to these solvents and cleaners, most of which are classified as toxic. Tightening government regulations have already excluded the use of some chemicals, and restrict the use of various halogenated hydrocarbons because of their atmospheric-ozone depleting effects, as well as their cancer-related risks. As a result, a program was established to develop an efficient, easily accessible, electronic solvent utilization handbook. This is being accomplished by: (1) identifying solvents (alternatives) that are not currently restricted by government regulations for use DOE-DP facilities, and private industry, (2) evaluating their cleaning performance, (3) evaluating their corrosivity, (4) evaluating their air emissions, (5) evaluating the possibility of recycling or recovering all or portions of the alternative degreasers, (6) testing substitute solvents compatibility with non-metallic materials, (7) inputting all of the data gathered (including previous biodegradability information) into a database, and (8) developing a methodology for efficient, widespread access to the data base information system.

  11. Cosmology and the weak interaction

    NASA Technical Reports Server (NTRS)

    Schramm, David N.

    1989-01-01

    The weak interaction plays a critical role in modern Big Bang cosmology. Two of its most publicized comological connections are emphasized: big bang nucleosynthesis and dark matter. The first of these is connected to the cosmological prediction of neutrine flavors, N(sub nu) is approximately 3 which in now being confirmed. The second is interrelated to the whole problem of galacty and structure formation in the universe. The role of the weak interaction both for dark matter candidates and for the problem of generating seeds to form structure is demonstrated.

  12. Weak value amplification considered harmful

    NASA Astrophysics Data System (ADS)

    Ferrie, Christopher; Combes, Joshua

    2014-03-01

    We show using statistically rigorous arguments that the technique of weak value amplification does not perform better than standard statistical techniques for the tasks of parameter estimation and signal detection. We show that using all data and considering the joint distribution of all measurement outcomes yields the optimal estimator. Moreover, we show estimation using the maximum likelihood technique with weak values as small as possible produces better performance for quantum metrology. In doing so, we identify the optimal experimental arrangement to be the one which reveals the maximal eigenvalue of the square of system observables. We also show these conclusions do not change in the presence of technical noise.

  13. Cosmology and the weak interaction

    SciTech Connect

    Schramm, D.N. ):)

    1989-12-01

    The weak interaction plays a critical role in modern Big Bang cosmology. This review will emphasize two of its most publicized cosmological connections: Big Bang nucleosynthesis and Dark Matter. The first of these is connected to the cosmological prediction of Neutrino Flavours, N{sub {nu}} {approximately} 3 which is now being confirmed at SLC and LEP. The second is interrelated to the whole problem of galaxy and structure formation in the universe. This review will demonstrate the role of the weak interaction both for dark matter candidates and for the problem of generating seeds to form structure. 87 refs., 3 figs., 5 tabs.

  14. Solvent reorganization of electron transitions in viscous solvents

    SciTech Connect

    Ghorai, Pradip K.; Matyushov, Dmitry V.

    2006-04-14

    We develop a model of electron transfer reactions at conditions of nonergodicity when the time of solvent relaxation crosses the observation time window set up by the reaction rate. Solvent reorganization energy of intramolecular electron transfer in a charge-transfer molecule dissolved in water and acetonitrile is studied by molecular dynamics simulations at varying temperatures. We observe a sharp decrease of the reorganization energy at a temperature identified as the temperature of structural arrest due to cage effect, as discussed by the mode-coupling theory. This temperature also marks the onset of the enhancement of translational diffusion relative to rotational relaxation signaling the breakdown of the Stokes-Einstein relation. The change in the reorganization energy at the transition temperature reflects the dynamical arrest of the slow, collective relaxation of the solvent related to the relaxation of the solvent dipolar polarization. An analytical theory proposed to describe this effect agrees well with both the simulations and experimental Stokes shift data. The theory is applied to the analysis of charge-transfer kinetics in a low-temperature glass former. We show that the reorganization energy is substantially lower than its equilibrium value for the low-temperature portion of the data. The theory predicts the possibility of discontinuous changes in the dependence of the electron transfer rate on the free energy gap when the reaction switches between ergodic and nonergodic regimes.

  15. Cosmology with weak lensing surveys.

    PubMed

    Munshi, Dipak; Valageas, Patrick

    2005-12-15

    Weak gravitational lensing is responsible for the shearing and magnification of the images of high-redshift sources due to the presence of intervening mass. Since the lensing effects arise from deflections of the light rays due to fluctuations of the gravitational potential, they can be directly related to the underlying density field of the large-scale structures. Weak gravitational surveys are complementary to both galaxy surveys and cosmic microwave background observations as they probe unbiased nonlinear matter power spectra at medium redshift. Ongoing CMBR experiments such as WMAP and a future Planck satellite mission will measure the standard cosmological parameters with unprecedented accuracy. The focus of attention will then shift to understanding the nature of dark matter and vacuum energy: several recent studies suggest that lensing is the best method for constraining the dark energy equation of state. During the next 5 year period, ongoing and future weak lensing surveys such as the Joint Dark Energy Mission (JDEM; e.g. SNAP) or the Large-aperture Synoptic Survey Telescope will play a major role in advancing our understanding of the universe in this direction. In this review article, we describe various aspects of probing the matter power spectrum and the bi-spectrum and other related statistics with weak lensing surveys. This can be used to probe the background dynamics of the universe as well as the nature of dark matter and dark energy.

  16. Weak localization of seismic waves.

    PubMed

    Larose, E; Margerin, L; Van Tiggelen, B A; Campillo, M

    2004-07-23

    We report the observation of weak localization of seismic waves in a natural environment. It emerges as a doubling of the seismic energy around the source within a spot of the width of a wavelength, which is several tens of meters in our case. The characteristic time for its onset is the scattering mean-free time that quantifies the internal heterogeneity.

  17. Cosmology with weak lensing surveys.

    PubMed

    Munshi, Dipak; Valageas, Patrick

    2005-12-15

    Weak gravitational lensing is responsible for the shearing and magnification of the images of high-redshift sources due to the presence of intervening mass. Since the lensing effects arise from deflections of the light rays due to fluctuations of the gravitational potential, they can be directly related to the underlying density field of the large-scale structures. Weak gravitational surveys are complementary to both galaxy surveys and cosmic microwave background observations as they probe unbiased nonlinear matter power spectra at medium redshift. Ongoing CMBR experiments such as WMAP and a future Planck satellite mission will measure the standard cosmological parameters with unprecedented accuracy. The focus of attention will then shift to understanding the nature of dark matter and vacuum energy: several recent studies suggest that lensing is the best method for constraining the dark energy equation of state. During the next 5 year period, ongoing and future weak lensing surveys such as the Joint Dark Energy Mission (JDEM; e.g. SNAP) or the Large-aperture Synoptic Survey Telescope will play a major role in advancing our understanding of the universe in this direction. In this review article, we describe various aspects of probing the matter power spectrum and the bi-spectrum and other related statistics with weak lensing surveys. This can be used to probe the background dynamics of the universe as well as the nature of dark matter and dark energy. PMID:16286284

  18. N-{Delta} weak transition

    SciTech Connect

    Graczyk, Krzysztof M.

    2011-11-23

    A short review of the Rein-Sehgal and isobar models is presented. The attention is focused on the nucleon-{Delta}(1232) weak transition form-factors. The results of the recent re-analyses of the ANL and BNL bubble chamber neutrino-deuteron scattering data are discussed.

  19. Automated Solvent Seaming of Large Polyimide Membranes

    NASA Technical Reports Server (NTRS)

    Rood, Robert; Moore, James D.; Talley, Chris; Gierow, Paul A.

    2006-01-01

    A solvent-based welding process enables the joining of precise, cast polyimide membranes at their edges to form larger precise membranes. The process creates a homogeneous, optical-quality seam between abutting membranes, with no overlap and with only a very localized area of figure disturbance. The seam retains 90 percent of the strength of the parent material. The process was developed for original use in the fabrication of wide-aperture membrane optics, with areal densities of less than 1 kg/m2, for lightweight telescopes, solar concentrators, antennas, and the like to be deployed in outer space. The process is just as well applicable to the fabrication of large precise polyimide membranes for flat or inflatable solar concentrators and antenna reflectors for terrestrial applications. The process is applicable to cast membranes made of CP1 (or equivalent) polyimide. The process begins with the precise fitting together and fixturing of two membrane segments. The seam is formed by applying a metered amount of a doped solution of the same polyimide along the abutting edges of the membrane segments. After the solution has been applied, the fixtured films are allowed to dry and are then cured by convective heating. The weld material is the same as the parent material, so that what is formed is a homogeneous, strong joint that is almost indistinguishable from the parent material. The success of the process is highly dependent on formulation of the seaming solution from the correct proportion of the polyimide in a suitable solvent. In addition, the formation of reliable seams depends on the deposition of a precise amount of the seaming solution along the seam line. To ensure the required precision, deposition is performed by use of an automated apparatus comprising a modified commercially available, large-format, ink-jet print head on an automated positioning table. The printing head jets the seaming solution into the seam area at a rate controlled in coordination with

  20. Modeling Solvent Broadening on the Vibronic Spectra of a Series of Coumarin Dyes. From Implicit to Explicit Solvent Models.

    PubMed

    Cerezo, Javier; Avila Ferrer, Francisco J; Prampolini, Giacomo; Santoro, Fabrizio

    2015-12-01

    We present a protocol to estimate the solvent-induced broadening of electronic spectra based on a model that explicitly takes into account the environment embedding the solute. Starting from a classical approximation of the solvent contribution to the spectrum, the broadening arises from the spread of the excitation energies due to the fluctuation of the solvent coordinates, and it is represented as a Gaussian line shape that convolutes the vibronic spectrum of the solute. The latter is computed in harmonic approximation at room temperature with a time-dependent approach. The proposed protocol for the computation of spectral broadening exploits molecular dynamics (MD) simulations performed on the solute-solvent system, keeping the solute degrees of freedom frozen, followed by the computation of the excitation properties with a quantum mechanics/molecular mechanics (QM/MM) approach. The factors that might influence each step of the protocol are analyzed in detail, including the selection of the empirical force field (FF) adopted in the MD simulations and the QM/MM partition of the system to compute the excitation energies. The procedure is applied to a family of coumarin dyes, and the results are compared with experiments and with the predictions of a very recent work (Cerezo et al., Phys. Chem. Chem. Phys. 2015, 17, 11401-11411), where an implicit model was adopted for the solvent. The final spectra of the considered coumarins were obtained without including ad hoc phenomenological parameters and indicate that the broadenings computed with explicit and implicit models both follow the experimental trend, increasing as the polarity change from the initial to the final state increases. More in detail, the implicit model provides larger estimations of the broadening that are closer to the experimental evidence, while explicit models appear to better capture relative differences arising from different solvents or different solutes. Possible inaccuracies of the adopted

  1. Weakly-bridged dimeric diorganotin(IV) compounds derived from pyruvic acid hydrazone Schiff base ligands: Synthesis, characterization and crystal structures

    NASA Astrophysics Data System (ADS)

    Hong, Min; Yin, Han-Dong; Cui, Ji-Chun

    2011-03-01

    We report the synthesis of four diorganotin(IV) compounds of Schiff base pyruvic acid hydrazone derivatives formulated as [R 2SnLY] 2, where L 1 is 2-SC 4H 3CON 2C(CH 3)CO 2 with Y = CH 3CH 2CH 2CH 2OH, R = n-Bu ( 1); L 2 is C 6H 5CON 2C(CH 3)CO 2 with Y = CH 3CH 2OH, R = p-F-Bz ( 2); L 3 is 2-HOC 6H 4CON 2C(CH 3)CO 2 with Y dbnd H 2O, R = p-CN -Bz ( 3); and L 4 is 4-NO 2-C 6H 4CON 2C(CH 3)CO 2 with Y dbnd CH 3CH 2OH, R = Bz ( 4). The structures of all compounds have been established by a combination of single-crystal X-ray diffraction analysis, 1H and 119Sn NMR spectroscopy, IR spectroscopy, and elemental analysis. Studies reveal that four ligands present the same coordination mode with tin center, which all present tridentate ONO donor Schiff bases and coordinate to the tin center in an enolic form. In compounds 1- 4, each tin atom is seven-coordinated and exhibits a distorted pentagonal bipyramid with a planar SnO 4N unit and two apical alkyl carbon atoms, thus forming a weakly-bridged dimeric molecule. Additionally, the distance of Sn⋯O bridge in each compound is obviously affected by the choice of different alkyl groups and coordination solvent molecules, which fluctuates in the range of 2.571(5)-2.839(4) Å. Furthermore, the supramolecular structure analysis show that there are two types of supramolecular infrastructures, 1D chain or 2D network, which are formed by intermolecular O-H···N or C-H⋯X (X = O, N or F) hydrogen bonds.

  2. Solvent-Dependent Pyranopterin Cyclization in Molybdenum Cofactor Model Complexes.

    PubMed

    Williams, Benjamin R; Gisewhite, Douglas; Kalinsky, Anna; Esmail, Alisha; Burgmayer, Sharon J Nieter

    2015-09-01

    The conserved pterin dithiolene ligand that coordinates molybdenum (Mo) in the cofactor (Moco) of mononuclear Mo enzymes can exist in both a tricyclic pyranopterin dithiolene form and as a bicyclic pterin-dithiolene form as observed in protein crystal structures of several bacterial molybdoenzymes. Interconversion between the tricyclic and bicyclic forms via pyran scission and cyclization has been hypothesized to play a role in the catalytic mechanism of Moco. Therefore, understanding the interconversion between the tricyclic and bicyclic forms, a type of ring-chain tautomerism, is an important aspect of study to understand its role in catalysis. In this study, equilibrium constants (K(eq)) as well as enthalpy, entropy, and free energy values are obtained for pyran ring tautomerism exhibited by two Moco model complexes, namely, (Et4N)[Tp*Mo(O)(S2BMOPP)] (1) and (Et4N)[Tp*Mo(O)(S2PEOPP)] (2), as a solvent-dependent equilibrium process. Keq values obtained from (1)H NMR data in seven deuterated solvents show a correlation between solvent polarity and tautomer form, where solvents with higher polarity parameters favor the pyran form.

  3. Competing weak localization and weak antilocalization in ultrathin topological insulators.

    PubMed

    Lang, Murong; He, Liang; Kou, Xufeng; Upadhyaya, Pramey; Fan, Yabin; Chu, Hao; Jiang, Ying; Bardarson, Jens H; Jiang, Wanjun; Choi, Eun Sang; Wang, Yong; Yeh, Nai-Chang; Moore, Joel; Wang, Kang L

    2013-01-01

    We demonstrate evidence of a surface gap opening in topological insulator (TI) thin films of (Bi(0.57)Sb(0.43))(2)Te(3) below six quintuple layers through transport and scanning tunneling spectroscopy measurements. By effective tuning the Fermi level via gate-voltage control, we unveil a striking competition between weak localization and weak antilocalization at low magnetic fields in nonmagnetic ultrathin films, possibly owing to the change of the net Berry phase. Furthermore, when the Fermi level is swept into the surface gap of ultrathin samples, the overall unitary behaviors are revealed at higher magnetic fields, which are in contrast to the pure WAL signals obtained in thicker films. Our findings show an exotic phenomenon characterizing the gapped TI surface states and point to the future realization of quantum spin Hall effect and dissipationless TI-based applications.

  4. A carbohydrate-anion recognition system in aprotic solvents.

    PubMed

    Ren, Bo; Dong, Hai; Ramström, Olof

    2014-05-01

    A carbohydrate-anion recognition system in nonpolar solvents is reported, in which complexes form at the B-faces of β-D-pyranosides with H1-, H3-, and H5-cis patterns similar to carbohydrate-π interactions. The complexation effect was evaluated for a range of carbohydrate structures; it resulted in either 1:1 carbohydrate-anion complexes, or 1:2 complex formation depending on the protection pattern of the carbohydrate. The interaction was also evaluated with different anions and solvents. In both cases it resulted in significant binding differences. The results indicate that complexation originates from van der Waals interactions or weak CH⋅⋅⋅A(-) hydrogen bonds between the binding partners and is related to electron-withdrawing groups of the carbohydrates as well as increased hydrogen-bond-accepting capability of the anions. PMID:24616327

  5. Phase behavior and second osmotic virial coefficient for competitive polymer solvation in mixed solvent solutions.

    PubMed

    Dudowicz, Jacek; Freed, Karl F; Douglas, Jack F

    2015-11-21

    We apply our recently developed generalized Flory-Huggins (FH) type theory for the competitive solvation of polymers by two mixed solvents to explain general trends in the variation of phase boundaries and solvent quality (quantified by the second osmotic virial coefficient B2) with solvent composition. The complexity of the theoretically predicted miscibility patterns for these ternary mixtures arises from the competitive association between the polymer and the solvents and from the interplay of these associative interactions with the weak van der Waals interactions between all components of the mixture. The main focus here lies in determining the influence of the free energy parameters for polymer-solvent association (solvation) and the effective FH interaction parameters {χαβ} (driving phase separation) on the phase boundaries (specifically the spinodals), the second osmotic virial coefficient B2, and the relation between the positions of the spinodal curves and the theta temperatures at which B2 vanishes. Our classification of the predicted miscibility patterns is relevant to numerous applications of ternary polymer solutions in industrial formulations and the use of mixed solvent systems for polymer characterization, such as chromatographic separation where mixed solvents are commonly employed. A favorable comparison of B2 with experimental data for poly(methyl methacrylate)/acetonitrile/methanol (or 1-propanol) solutions only partially supports the validity of our theoretical predictions due to the lack of enough experimental data and the neglect of the self and mutual association of the solvents.

  6. Phase behavior and second osmotic virial coefficient for competitive polymer solvation in mixed solvent solutions

    NASA Astrophysics Data System (ADS)

    Dudowicz, Jacek; Freed, Karl F.; Douglas, Jack F.

    2015-11-01

    We apply our recently developed generalized Flory-Huggins (FH) type theory for the competitive solvation of polymers by two mixed solvents to explain general trends in the variation of phase boundaries and solvent quality (quantified by the second osmotic virial coefficient B 2 ) with solvent composition. The complexity of the theoretically predicted miscibility patterns for these ternary mixtures arises from the competitive association between the polymer and the solvents and from the interplay of these associative interactions with the weak van der Waals interactions between all components of the mixture. The main focus here lies in determining the influence of the free energy parameters for polymer-solvent association (solvation) and the effective FH interaction parameters {χαβ} (driving phase separation) on the phase boundaries (specifically the spinodals), the second osmotic virial coefficient B 2 , and the relation between the positions of the spinodal curves and the theta temperatures at which B 2 vanishes. Our classification of the predicted miscibility patterns is relevant to numerous applications of ternary polymer solutions in industrial formulations and the use of mixed solvent systems for polymer characterization, such as chromatographic separation where mixed solvents are commonly employed. A favorable comparison of B 2 with experimental data for poly(methyl methacrylate)/acetonitrile/methanol (or 1-propanol) solutions only partially supports the validity of our theoretical predictions due to the lack of enough experimental data and the neglect of the self and mutual association of the solvents.

  7. A flexible polymer chain in a critical solvent: Coil or globule?

    NASA Astrophysics Data System (ADS)

    Budkov, Yu. A.; Kolesnikov, A. L.; Georgi, N.; Kiselev, M. G.

    2015-02-01

    We study the behavior of a flexible polymer chain in the presence of a low-molecular weight solvent in the vicinity of a liquid-gas critical point within the framework of a self-consistent field theory. The total free energy of the dilute polymer solution is expressed as a function of the radius of gyration of the polymer and the average solvent number density within the gyration volume at the level of the mean-field approximation. Varying the strength of attraction between polymer and solvent we show that two qualitatively different regimes occur at the liquid-gas critical point. In case of weak polymer-solvent interactions the polymer chain is in a globular state. On the contrary, in case of strong polymer-solvent interactions the polymer chain attains an expanded conformation. We discuss the influence of the critical solvent density fluctuations on the polymer conformation. The reported effect could be used to excert control on the polymer conformation by changing the thermodynamic state of the solvent. It could also be helpful to estimate the solvent density within the gyration volume of the polymer for drug delivery and molecular imprinting applications.

  8. Variational Optimization of an All-Atom Implicit Solvent Force Field to Match Explicit Solvent Simulation Data.

    PubMed

    Bottaro, Sandro; Lindorff-Larsen, Kresten; Best, Robert B

    2013-12-10

    The development of accurate implicit solvation models with low computational cost is essential for addressing many large-scale biophysical problems. Here, we present an efficient solvation term based on a Gaussian solvent-exclusion model (EEF1) for simulations of proteins in aqueous environment, with the primary aim of having a good overlap with explicit solvent simulations, particularly for unfolded and disordered states - as would be needed for multiscale applications. In order to achieve this, we have used a recently proposed coarse-graining procedure based on minimization of an entropy-related objective function to train the model to reproduce the equilibrium distribution obtained from explicit water simulations. Via this methodology, we have optimized both a charge screening parameter and a backbone torsion term against explicit solvent simulations of an α-helical and a β-stranded peptide. The performance of the resulting effective energy function, termed EEF1-SB, is tested with respect to the properties of folded proteins, the folding of small peptides or fast-folding proteins, and NMR data for intrinsically disordered proteins. The results show that EEF1-SB provides a reasonable description of a wide range of systems, but its key advantage over other methods tested is that it captures very well the structure and dimension of disordered or weakly structured peptides. EEF1-SB is thus a computationally inexpensive (~ 10 times faster than Generalized-Born methods) and transferable approximation for treating solvent effects. PMID:24748852

  9. Organic Solvent Effects in Biomass Conversion Reactions.

    PubMed

    Shuai, Li; Luterbacher, Jeremy

    2016-01-01

    Transforming lignocellulosic biomass into fuels and chemicals has been intensely studied in recent years. A large amount of work has been dedicated to finding suitable solvent systems, which can improve the transformation of biomass into value-added chemicals. These efforts have been undertaken based on numerous research results that have shown that organic solvents can improve both conversion and selectivity of biomass to platform molecules. We present an overview of these organic solvent effects, which are harnessed in biomass conversion processes, including conversion of biomass to sugars, conversion of sugars to furanic compounds, and production of lignin monomers. A special emphasis is placed on comparing the solvent effects on conversion and product selectivity in water with those in organic solvents while discussing the origins of the differences that arise. We have categorized results as benefiting from two major types of effects: solvent effects on solubility of biomass components including cellulose and lignin and solvent effects on chemical thermodynamics including those affecting reactants, intermediates, products, and/or catalysts. Finally, the challenges of using organic solvents in industrial processes are discussed from the perspective of solvent cost, solvent stability, and solvent safety. We suggest that a holistic view of solvent effects, the mechanistic elucidation of these effects, and the careful consideration of the challenges associated with solvent use could assist researchers in choosing and designing improved solvent systems for targeted biomass conversion processes.

  10. Organic Solvent Effects in Biomass Conversion Reactions.

    PubMed

    Shuai, Li; Luterbacher, Jeremy

    2016-01-01

    Transforming lignocellulosic biomass into fuels and chemicals has been intensely studied in recent years. A large amount of work has been dedicated to finding suitable solvent systems, which can improve the transformation of biomass into value-added chemicals. These efforts have been undertaken based on numerous research results that have shown that organic solvents can improve both conversion and selectivity of biomass to platform molecules. We present an overview of these organic solvent effects, which are harnessed in biomass conversion processes, including conversion of biomass to sugars, conversion of sugars to furanic compounds, and production of lignin monomers. A special emphasis is placed on comparing the solvent effects on conversion and product selectivity in water with those in organic solvents while discussing the origins of the differences that arise. We have categorized results as benefiting from two major types of effects: solvent effects on solubility of biomass components including cellulose and lignin and solvent effects on chemical thermodynamics including those affecting reactants, intermediates, products, and/or catalysts. Finally, the challenges of using organic solvents in industrial processes are discussed from the perspective of solvent cost, solvent stability, and solvent safety. We suggest that a holistic view of solvent effects, the mechanistic elucidation of these effects, and the careful consideration of the challenges associated with solvent use could assist researchers in choosing and designing improved solvent systems for targeted biomass conversion processes. PMID:26676907

  11. Social Postural Coordination

    ERIC Educational Resources Information Center

    Varlet, Manuel; Marin, Ludovic; Lagarde, Julien; Bardy, Benoit G.

    2011-01-01

    The goal of the current study was to investigate whether a visual coupling between two people can produce spontaneous interpersonal postural coordination and change their intrapersonal postural coordination involved in the control of stance. We examined the front-to-back head displacements of participants and the angular motion of their hip and…

  12. 6. Coordination and control.

    PubMed

    2014-05-01

    Any complex operation requires a system for management. In most societies, disaster management is the responsibility of the government. Coordination and control is a system that provides the oversight for all of the disaster management functions. The roles and responsibilities of a coordination and control centre include: (1) planning; (2) maintenance of inventories; (3) activation of the disaster response plan; (4) application of indicators of function; (5) surveillance; (6) information management; (7) coordination of activities of the BSFs; (8) decision-making; (9) priority setting; (10) defining overarching goal and objectives for interventions; (11) applying indicators of effectiveness; (12) applying indicators of benefit and impact; (13) exercising authority; (14) managing resources; (15) initiating actions; (16) preventing influx of unneeded resources; (17) defining progress; (18) providing information; (19) liasing with responding organisations; and (20) providing quality assurance. Coordination and control is impossible without communications. To accomplish coordination and control, three factors must be present: (1) mandate; (2) power and authority; and (3) available resources. Coordination and control is responsible for the evaluation of the effectiveness and benefits/impacts of all interventions. Coordination and control centres (CCCs) are organised hierarchically from the on-scene CCCs (incident command) to local provincial to national CCCs. Currently, no comprehensive regional and international CCCs have been universally endorsed. Systems such as the incident command system, the unified command system, and the hospital incident command system are described as are the humanitarian reform movement and the importance of coordination and control in disaster planning and preparedness.

  13. IVS Technology Coordinator Report

    NASA Technical Reports Server (NTRS)

    Whitney, Alan

    2013-01-01

    This report of the Technology Coordinator includes the following: 1) continued work to implement the new VLBI2010 system, 2) the 1st International VLBI Technology Workshop, 3) a VLBI Digital- Backend Intercomparison Workshop, 4) DiFX software correlator development for geodetic VLBI, 5) a review of progress towards global VLBI standards, and 6) a welcome to new IVS Technology Coordinator Bill Petrachenko.

  14. Solvents and Parkinson disease: A systematic review of toxicological and epidemiological evidence

    SciTech Connect

    Lock, Edward A.; Zhang, Jing; Checkoway, Harvey

    2013-02-01

    Parkinson disease (PD) is a debilitating neurodegenerative motor disorder, with its motor symptoms largely attributable to loss of dopaminergic neurons in the substantia nigra. The causes of PD remain poorly understood, although environmental toxicants may play etiologic roles. Solvents are widespread neurotoxicants present in the workplace and ambient environment. Case reports of parkinsonism, including PD, have been associated with exposures to various solvents, most notably trichloroethylene (TCE). Animal toxicology studies have been conducted on various organic solvents, with some, including TCE, demonstrating potential for inducing nigral system damage. However, a confirmed animal model of solvent-induced PD has not been developed. Numerous epidemiologic studies have investigated potential links between solvents and PD, yielding mostly null or weak associations. An exception is a recent study of twins indicating possible etiologic relations with TCE and other chlorinated solvents, although findings were based on small numbers, and dose–response gradients were not observed. At present, there is no consistent evidence from either the toxicological or epidemiologic perspective that any specific solvent or class of solvents is a cause of PD. Future toxicological research that addresses mechanisms of nigral damage from TCE and its metabolites, with exposure routes and doses relevant to human exposures, is recommended. Improvements in epidemiologic research, especially with regard to quantitative characterization of long-term exposures to specific solvents, are needed to advance scientific knowledge on this topic. -- Highlights: ► The potential for organic solvents to cause Parkinson's disease has been reviewed. ► Twins study suggests etiologic relations with chlorinated solvents and Parkinson's. ► Animal studies with TCE showed potential to cause damage to dopaminergic neurons. ► Need to determine if effects in animals are relevant to human exposure

  15. Which solvent for olfactory testing?

    PubMed

    Philpott, C M; Goodenough, P C; Wolstenholme, C R; Murty, G E

    2004-12-01

    The physical properties of any carrier can deteriorate over time and thus alter the results in any olfactory test. The aim of this study was to evaluate clinically potential solvents as a clean odourless carrier for olfactory testing. Sweet almond oil, pure coconut oil, pure peach kernel oil, dipropylene glycol, monopropylene glycol, mineral oil and silicone oil were studied. The experimentation was conducted in two parts. First, an olfactory device was used to conduct air through the solvents on a weekly basis using a cohort of six volunteers to assess the perceived odour of each solvent at weekly intervals. Secondly a cross-reference test was performed using small bottled solutions of phenylethyl-alcohol and 1-butanol in 10-fold dilutions to compare any perceived difference in concentrations over a period of 8 weeks. We concluded that mineral oil is the most suitable carrier for the purpose of olfactory testing, possessing many desirable characteristics of an olfactory solvent, and that silicone oil may provide a suitable alternative for odorants with which it is miscible.

  16. Weak values and weak coupling maximizing the output of weak measurements

    SciTech Connect

    Di Lorenzo, Antonio

    2014-06-15

    In a weak measurement, the average output 〈o〉 of a probe that measures an observable A{sup -hat} of a quantum system undergoing both a preparation in a state ρ{sub i} and a postselection in a state E{sub f} is, to a good approximation, a function of the weak value A{sub w}=Tr[E{sub f}A{sup -hat} ρ{sub i}]/Tr[E{sub f}ρ{sub i}], a complex number. For a fixed coupling λ, when the overlap Tr[E{sub f}ρ{sub i}] is very small, A{sub w} diverges, but 〈o〉 stays finite, often tending to zero for symmetry reasons. This paper answers the questions: what is the weak value that maximizes the output for a fixed coupling? What is the coupling that maximizes the output for a fixed weak value? We derive equations for the optimal values of A{sub w} and λ, and provide the solutions. The results are independent of the dimensionality of the system, and they apply to a probe having a Hilbert space of arbitrary dimension. Using the Schrödinger–Robertson uncertainty relation, we demonstrate that, in an important case, the amplification 〈o〉 cannot exceed the initial uncertainty σ{sub o} in the observable o{sup -hat}, we provide an upper limit for the more general case, and a strategy to obtain 〈o〉≫σ{sub o}. - Highlights: •We have provided a general framework to find the extremal values of a weak measurement. •We have derived the location of the extremal values in terms of preparation and postselection. •We have devised a maximization strategy going beyond the limit of the Schrödinger–Robertson relation.

  17. Replacement solvents for use in chemical synthesis

    DOEpatents

    Molnar, Linda K.; Hatton, T. Alan; Buchwald, Stephen L.

    2001-05-15

    Replacement solvents for use in chemical synthesis include polymer-immobilized solvents having a flexible polymer backbone and a plurality of pendant groups attached onto the polymer backbone, the pendant groups comprising a flexible linking unit bound to the polymer backbone and to a terminal solvating moiety. The polymer-immobilized solvent may be dissolved in a benign medium. Replacement solvents for chemical reactions for which tetrahydrofuran or diethyl may be a solvent include substituted tetrahydrofurfuryl ethers and substituted tetrahydro-3-furan ethers. The replacement solvents may be readily recovered from the reaction train using conventional methods.

  18. Weak Coupling in 143Nd

    NASA Astrophysics Data System (ADS)

    Zhou, Xiao-Hong; E, Ideguchi; T, Kishida; M, Ishihara; H, Tsuchida; Y, Gono; T, Morikawa; M, Shibata; H, Watanabe; M, Miyake; T, Tsutsumi; S, Motomura; S, Mitarai

    2000-04-01

    The high-spin states of 143Nd have been studied in the 130Te(18O, 5n)143Nd reaction at a beam energy of 80 MeV using techniques of in-beam γ-ray spectroscopy. Measurements of γ - γ - t coincidences, γ-ray angular distributions, and γ-ray linear polarizations were performed. A level scheme of 143Nd with spin and parity assignments up to 53/2+ is proposed. While a weak coupling model can explain the level structure up to the Jπ=39/2- state, this model can not reproduce the higher-lying states. Additionally, a new low-lying non-yrast level sequence in 143Nd was observed in the present work, which can be well described by the weak coupling of an i13/2 neutron to the 142Nd core nucleus.

  19. Overdamping by weakly coupled environments

    SciTech Connect

    Esposito, Massimiliano; Haake, Fritz

    2005-12-15

    A quantum system weakly interacting with a fast environment usually undergoes a relaxation with complex frequencies whose imaginary parts are damping rates quadratic in the coupling to the environment in accord with Fermi's 'golden rule'. We show for various models (spin damped by harmonic-oscillator or random-matrix baths, quantum diffusion, and quantum Brownian motion) that upon increasing the coupling up to a critical value still small enough to allow for weak-coupling Markovian master equations, a different relaxation regime can occur. In that regime, complex frequencies lose their real parts such that the process becomes overdamped. Our results call into question the standard belief that overdamping is exclusively a strong coupling feature.

  20. Optimizing SNAP for Weak Lensing

    NASA Astrophysics Data System (ADS)

    High, F. W.; Ellis, R. S.; Massey, R. J.; Rhodes, J. D.; Lamoureux, J. I.; SNAP Collaboration

    2004-12-01

    The Supernova/Acceleration Probe (SNAP) satellite proposes to measure weak gravitational lensing in addition to type Ia supernovae. Its pixel scale has been set to 0.10 arcsec per pixel as established by the needs of supernova observations. To find the optimal pixel scale for accurate weak lensing measurements we conduct a tradeoff study in which, via simulations, we fix the suvey size in total pixels and vary the pixel scale. Our preliminary results show that with a smaller scale of about 0.08 arcsec per pixel we can minimize the contribution of intrinsic shear variance to the error on the power spectrum of mass density distortion. Currently we are testing the robustness of this figure as well as determining whether dithering yields analogous results.

  1. Coordination sequences and coordination waves in matter

    SciTech Connect

    Rau, V. G. Pugaev, A. A.; Rau, T. F.

    2006-01-15

    A possible way of partitioning a space into polycubes (n-dimensional modifications of Golomb polyominoes, which are generally nonconvex) is used as a basic model of ordered matter structure. It is suggested that layer-by-layer growth of a structure, occurring along the geodetics of the digraph of a net defined by the local rules of bonding of polycubes, justifies the phenomenological laws of shaping (self-similarity during the growth, independence of the polyhedron shape on the 'seed,' the symmetry of the growth polyhedron, etc.). Specific results of the analysis of number sequences of the increase in coordination circles for planar periodic partitions of model and real crystal structures, as well as the preliminary results of investigation of standing coordination topological waves, revealed for the first time in computer experiments, are reported.

  2. Implicit treatment of solvent dispersion forces in protein simulations

    PubMed Central

    Hassan, Sergio A.

    2015-01-01

    A model is proposed for the evaluation of dispersive forces in a continuum solvent representation for use in large-scale computer simulations. It captures the short and long-range effects of water-exclusion in conditions of partial and anisotropic hydration. The model introduces three parameters, one of which represents the degree of hydration (water occupancy) at any point in the system, which depends on the solute conformation, and two that represent the strength of water-water and water-solute dispersive interactions. It is optimized for proteins, using hydration data of a sub-optimally hydrated binding site and results from dynamics simulations in explicit water. The model is applied to a series of aliphatic-alcohol/protein complexes and a set of binary and ternary complexes of various sizes. Implications for weak and ultra-weak protein-protein association and for simulation in crowded media are discussed. PMID:24919463

  3. Uranyl ion coordination

    USGS Publications Warehouse

    Evans, H.T.

    1963-01-01

    A review of the known crystal structures containing the uranyl ion shows that plane-pentagon coordination is equally as prevalent as plane-square or plane-hexagon. It is suggested that puckered-hexagon configurations of OH - or H2O about the uranyl group will tend to revert to plane-pentagon coordination. The concept of pentagonal coordination is invoked for possible explanations of the complex crystallography of the natural uranyl hydroxides and the unusual behavior of polynuclear ions in hydrolyzed uranyl solutions.

  4. Dipolar correlations in structured solvents under nanoconfinement

    NASA Astrophysics Data System (ADS)

    Buyukdagli, Sahin; Blossey, Ralf

    2014-06-01

    We study electrostatic correlations in structured solvents confined to nanoscale systems. We derive variational equations of Netz-Orland type for a model liquid composed of finite size dipoles. These equations are solved for both dilute solvents and solvents at physiological concentrations in a slit nanopore geometry. Correlation effects are of major importance for the dielectric reduction and anisotropy of the solvent resulting from dipole image interactions and also lead to a reduction of van der Waals attractions between low dielectric bodies. Finally, by comparison with other recently developed self-consistent theories and experiments, we scrutinize the effect of solvent-membrane interactions on the differential capacitance of the charged liquid in contact with low dielectric substrates. The interfacial solvent depletion driven by solvent-image interactions plays the major role in the observed low values of the experimental capacitance data, while non-locality associated with the extended charge structure of solvent molecules only brings a minor contribution.

  5. Dipolar correlations in structured solvents under nanoconfinement.

    PubMed

    Buyukdagli, Sahin; Blossey, Ralf

    2014-06-21

    We study electrostatic correlations in structured solvents confined to nanoscale systems. We derive variational equations of Netz-Orland type for a model liquid composed of finite size dipoles. These equations are solved for both dilute solvents and solvents at physiological concentrations in a slit nanopore geometry. Correlation effects are of major importance for the dielectric reduction and anisotropy of the solvent resulting from dipole image interactions and also lead to a reduction of van der Waals attractions between low dielectric bodies. Finally, by comparison with other recently developed self-consistent theories and experiments, we scrutinize the effect of solvent-membrane interactions on the differential capacitance of the charged liquid in contact with low dielectric substrates. The interfacial solvent depletion driven by solvent-image interactions plays the major role in the observed low values of the experimental capacitance data, while non-locality associated with the extended charge structure of solvent molecules only brings a minor contribution. PMID:24952564

  6. Dipolar correlations in structured solvents under nanoconfinement.

    PubMed

    Buyukdagli, Sahin; Blossey, Ralf

    2014-06-21

    We study electrostatic correlations in structured solvents confined to nanoscale systems. We derive variational equations of Netz-Orland type for a model liquid composed of finite size dipoles. These equations are solved for both dilute solvents and solvents at physiological concentrations in a slit nanopore geometry. Correlation effects are of major importance for the dielectric reduction and anisotropy of the solvent resulting from dipole image interactions and also lead to a reduction of van der Waals attractions between low dielectric bodies. Finally, by comparison with other recently developed self-consistent theories and experiments, we scrutinize the effect of solvent-membrane interactions on the differential capacitance of the charged liquid in contact with low dielectric substrates. The interfacial solvent depletion driven by solvent-image interactions plays the major role in the observed low values of the experimental capacitance data, while non-locality associated with the extended charge structure of solvent molecules only brings a minor contribution.

  7. 3-methyl-2-oxazolidone as a solvent for acid-base titrations.

    PubMed

    Taphorn, J E; Davies, G M; Caruso, J A

    1975-07-01

    3-Methyl-2-oxazolidone has been evaluated as a solvent for the titration of various weak carboxylic acids and phenols. Its high dielectric constant and wide liquid range contribute to its outstanding solvent properties. Tetrabutylammonium hydroxide was the titrant. End-points were determined potentiometrically with a glass-calomel electrode system. FORTRAN computer programs were used to evaluate the results, and relative acid strengths were determined and related to the aqueous acidity. The accuracies obtained are comparable to those for other solvent media. An 800-mV potential span is available in this solvent, which may allow differentiating titrations to be performed. No titrations of acid mixtures were attempted, but it was found possible to distinguish both neutralization steps for salicylic acid and o-phthalic acid.

  8. Micro practices of coordination based on complex adaptive systems: user needs and strategies for coordinating public health in Denmark

    PubMed Central

    Wittrup, Inge; Burau, Viola

    2015-01-01

    Introduction Many highly formalised approaches to coordination poorly fit public health and recent studies call for coordination based on complex adaptive systems. Our contribution is two-fold. Empirically, we focus on public health, and theoretically we build on the patient perspective and treat coordination as a process of contingent, two-level negotiations of user needs. Theory and Methods The paper draws on the concept of user needs-based coordination and sees coordination as a process, whereby needs emerging from the life world of the user are made amenable to the health system through negotiations. The analysis is based on an explorative case study of a health promotion initiative in Denmark. It adopts an anthropological qualitative approach and uses a range of qualitative data. Results The analysis identifies four strategies of coordination: the coordinator focusing on the individual user or on relations with other professionals; and the manager coaching the coordinator or providing structural support. Crucially, the coordination strategies by management remain weak as they do not directly relate to specific user needs. Discussion In process of bottom-up negotiations user needs become blurred and this is especially a challenge for management. The study therefore calls for an increased focus on the level nature of negotiations to bridge the gap that currently weakens coordination strategies by management. PMID:26528097

  9. Is Water a Universal Solvent for Life?

    NASA Technical Reports Server (NTRS)

    Pohorill, Andrew

    2012-01-01

    There are strong reasons to believe that the laws, principles and constraints of physics and chemistry are universal. It is much less clear how this universality translates into our understanding of the origins of life. Conventionally, discussions of this topic focus on chemistry that must be sufficiently rich to seed life. Although this is clearly a prerequisite for the emergence of living systems, I propose to focus instead on self-organization of matter into functional structures capable of reproduction, evolution and responding to environmental changes. In biology, most essential functions are largely mediated by noncovalent interactions (interactions that do not involve making or breaking chemical bonds). Forming chemical bonds is only a small part of what living systems do. There are specific implications of this point of view for universality. I will concentrate on one of these implications. Strength of non-covalent interactions must be properly tuned. If they were too weak, the system would exhibit undesired, uncontrolled response to natural fluctuations of physical and chemical parameters. If they were too strong kinetics of biological processes would be slow and energetics costly. This balance, however, is not a natural property of complex chemical systems. Instead, it has to be achieved with the aid of an appropriate solvent for life. In particular, potential solvents for life must be characterized by a high dielectric constant to ensure solubility of polar species and sufficient flexibility of biological structures stabilized by electrostatic interactions. Among these solvents, water exhibits a remarkable trait that it also promotes solvophobic (hydrophobic) interactions between non-polar species, typically manifested by a tendency of these species to aggregate and minimize their contacts with the aqueous solvent. Hydrophobic interactions are responsible, at least in part, for many self-organization phenomena in biological systems, such as the formation

  10. Developmental coordination disorder

    MedlinePlus

    Physical causes and other types of learning disabilities must be ruled out before the diagnosis can be confirmed. ... Developmental coordination disorder can lead to: Learning problems ... wanting to participate in physical activities (such as sports)

  11. Understanding social motor coordination.

    PubMed

    Schmidt, R C; Fitzpatrick, Paula; Caron, Robert; Mergeche, Joanna

    2011-10-01

    Recently there has been much interest in social coordination of motor movements, or as it is referred to by some researchers, joint action. This paper reviews the cognitive perspective's common coding/mirror neuron theory of joint action, describes some of its limitations and then presents the behavioral dynamics perspective as an alternative way of understanding social motor coordination. In particular, behavioral dynamics' ability to explain the temporal coordination of interacting individuals is detailed. Two experiments are then described that demonstrate how dynamical processes of synchronization are apparent in the coordination underlying everyday joint actions such as martial art exercises, hand-clapping games, and conversations. The import of this evidence is that emergent dynamic patterns such as synchronization are the behavioral order that any neural substrate supporting joint action (e.g., mirror systems) would have to sustain.

  12. The solvent component of macromolecular crystals

    SciTech Connect

    Weichenberger, Christian X.; Kantardjieff, Katherine; Rupp, Bernhard

    2015-04-30

    On average, the mother liquor or solvent and its constituents occupy about 50% of a macromolecular crystal. Ordered as well as disordered solvent components need to be accurately accounted for in modelling and refinement, often with considerable complexity. The mother liquor from which a biomolecular crystal is grown will contain water, buffer molecules, native ligands and cofactors, crystallization precipitants and additives, various metal ions, and often small-molecule ligands or inhibitors. On average, about half the volume of a biomolecular crystal consists of this mother liquor, whose components form the disordered bulk solvent. Its scattering contributions can be exploited in initial phasing and must be included in crystal structure refinement as a bulk-solvent model. Concomitantly, distinct electron density originating from ordered solvent components must be correctly identified and represented as part of the atomic crystal structure model. Herein, are reviewed (i) probabilistic bulk-solvent content estimates, (ii) the use of bulk-solvent density modification in phase improvement, (iii) bulk-solvent models and refinement of bulk-solvent contributions and (iv) modelling and validation of ordered solvent constituents. A brief summary is provided of current tools for bulk-solvent analysis and refinement, as well as of modelling, refinement and analysis of ordered solvent components, including small-molecule ligands.

  13. Solvent Extraction of Furfural From Biomass

    NASA Technical Reports Server (NTRS)

    Humphrey, M. F.

    1984-01-01

    Solvent-extraction method reduces energy required to remove furfural produced during acid hydrolysis of biomass. Acid hydrolysis performed in vessel containing both solvents and reacting ingredients. With intimate contact between solvents and aqueous hydrolyis liqour, furfural removed form liquor almost as fast as it forms.

  14. The hype with ionic liquids as solvents

    NASA Astrophysics Data System (ADS)

    Kunz, Werner; Häckl, Katharina

    2016-09-01

    In this mini review, we give our personal opinion about the present state of the art concerning Ionic Liquids, proposed as alternative solvents. In particular, we consider their different drawbacks and disadvantages and discuss the critical aspects of the research of Ionic Liquids as solvents. Finally, we point out some aspects on potentially promising Ionic Liquid solvents.

  15. Firing of pulverized solvent refined coal

    DOEpatents

    Derbidge, T. Craig; Mulholland, James A.; Foster, Edward P.

    1986-01-01

    An air-purged burner for the firing of pulverized solvent refined coal is constructed and operated such that the solvent refined coal can be fired without the coking thereof on the burner components. The air-purged burner is designed for the firing of pulverized solvent refined coal in a tangentially fired boiler.

  16. Detecting weakly interacting massive particles.

    NASA Astrophysics Data System (ADS)

    Drukier, A. K.; Gelmini, G. B.

    The growing synergy between astrophysics, particle physics, and low background experiments strengthens the possibility of detecting astrophysical non-baryonic matter. The idea of direct detection is that an incident, massive weakly interacting particle could collide with a nucleus and transfer an energy that could be measured. The present low levels of background achieved by the PNL/USC Ge detector represent a new technology which yields interesting bounds on Galactic cold dark matter and on light bosons emitted from the Sun. Further improvements require the development of cryogenic detectors. The authors analyse the practicality of such detectors, their optimalization and background suppression using the "annual modulation effect".

  17. Weak lensing by galaxy troughs

    NASA Astrophysics Data System (ADS)

    Gruen, Daniel

    2016-06-01

    Galaxy troughs, i.e. underdensities in the projected galaxy field, are a weak lensing probe of the low density Universe with high signal-to-noise ratio. I present measurements of the radial distortion of background galaxy images and the de-magnification of the CMB by troughs constructed from Dark Energy Survey and Sloan Digital Sky Survey galaxy catalogs. With high statistical significance and a relatively robust modeling, these probe gravity in regimes of density and scale difficult to access for conventional statistics.

  18. Weak quasielastic production of hyperons

    SciTech Connect

    Singh, S. K.; Vacas, M. J. Vicente

    2006-09-01

    The quasielastic weak production of {lambda} and {sigma} hyperons from nucleons and nuclei induced by antineutrinos is studied in the energy region of some ongoing neutrino oscillation experiments in the intermediate energy region. The hyperon-nucleon transition form factors determined from neutrino-nucleon scattering and an analysis of high precision data on semileptonic decays of neutron and hyperons using SU(3) symmetry have been used. The nuclear effects due to Fermi motion and final state interaction effects due to hyperon-nucleon scattering have also been studied. The numerical results for differential and total cross sections have been presented.

  19. Tagged-weak {pi} method

    SciTech Connect

    Margaryan, A.; Hashimoto, O.; Kakoyan, V.; Knyazyan, S.; Tang, L.

    2011-02-15

    A new 'tagged-weak {pi} method' is proposed for determination of electromagnetic transition probabilities B(E2) and B(M1) of the hypernuclear states with lifetimes of {approx}10{sup -10} s. With this method, we are planning to measure B(E2) and B(M1) for light hypernuclei at JLab. The results of Monte Carlo simulations for the case of E2(5/2{sup +}, 3/2{sup +} {yields} 1/2{sup +}) transitions in {sub {Lambda}}{sup 7}He hypernuclei are presented.

  20. Solvent effects on the resonance Raman spectra of bacteriochlorophyll a cation radical

    NASA Astrophysics Data System (ADS)

    Misono, Yasuhito; Nishizawa, Ei-ichi; Limantara, Leenawaty; Koyama, Yasushi; Itoh, Koichi

    1995-04-01

    Resonance Raman (RR) spectra were measured for the cation radical of bacteriochlorophyll a in acetone, methanol, dichloromethane and mixed solvents of acetone and methanol. The ring-breathing (C a-C m stretching) frequency of the radical (abbreviated as vr+) was observed at 1601 cm -1 in acetone (forming a penta-coordinated monomer), at 1587 cm -1 in a methanol (forming a hexa-coordinated monomer) and at 1600 cm -1 in dichloromethane (forming a penta-coordinated aggregate). The RR spectrum of the radical in dichloromethane is almost identical to the transient RR spectrum ascribed to 'the aggregated T 1 species of Bchl a' formed in the particular solvent by Nishizawa, Limantara, Nanjou, Nagae, Kakuno and Koyama, indicating that their interpretation needs to be revised.

  1. Continuous parallel coordinates.

    PubMed

    Heinrich, Julian; Weiskopf, Daniel

    2009-01-01

    Typical scientific data is represented on a grid with appropriate interpolation or approximation schemes,defined on a continuous domain. The visualization of such data in parallel coordinates may reveal patterns latently contained in the data and thus can improve the understanding of multidimensional relations. In this paper, we adopt the concept of continuous scatterplots for the visualization of spatially continuous input data to derive a density model for parallel coordinates. Based on the point-line duality between scatterplots and parallel coordinates, we propose a mathematical model that maps density from a continuous scatterplot to parallel coordinates and present different algorithms for both numerical and analytical computation of the resulting density field. In addition, we show how the 2-D model can be used to successively construct continuous parallel coordinates with an arbitrary number of dimensions. Since continuous parallel coordinates interpolate data values within grid cells, a scalable and dense visualization is achieved, which will be demonstrated for typical multi-variate scientific data.

  2. Magnetic Coordinate Systems

    NASA Astrophysics Data System (ADS)

    Laundal, K. M.; Richmond, A. D.

    2016-07-01

    Geospace phenomena such as the aurora, plasma motion, ionospheric currents and associated magnetic field disturbances are highly organized by Earth's main magnetic field. This is due to the fact that the charged particles that comprise space plasma can move almost freely along magnetic field lines, but not across them. For this reason it is sensible to present such phenomena relative to Earth's magnetic field. A large variety of magnetic coordinate systems exist, designed for different purposes and regions, ranging from the magnetopause to the ionosphere. In this paper we review the most common magnetic coordinate systems and describe how they are defined, where they are used, and how to convert between them. The definitions are presented based on the spherical harmonic expansion coefficients of the International Geomagnetic Reference Field (IGRF) and, in some of the coordinate systems, the position of the Sun which we show how to calculate from the time and date. The most detailed coordinate systems take the full IGRF into account and define magnetic latitude and longitude such that they are constant along field lines. These coordinate systems, which are useful at ionospheric altitudes, are non-orthogonal. We show how to handle vectors and vector calculus in such coordinates, and discuss how systematic errors may appear if this is not done correctly.

  3. Solvent effect on intramolecular electron transfer rates of mixed-valence biferrocene monocation derivatives.

    PubMed

    Masuda, Y; Shimizu, C

    2006-06-01

    Intramolecular electron transfer (ET) rates in various solvents of mixed-valence biferrocene monocation (Fe(II), Fe(III)) and the 1',1' ''-diiodo and 1',1' ''-diethyl derivatives (respectively abbreviated as BFC(+), I(2)BFC(+), and Et(2)BFC(+)) were determined by means of the spin-lattice relaxation times of the protons, taking into account the local magnetic field fluctuation caused by the electron hopping between the two ferrocene units. We also determined the ET rates of a mixed-valence diferrocenylacetylene monocation (DFA(+)) in order to examine the effect of the insertion of an acetylene bridge between the two ferrocene units. The insertion of the bridge decreased the ET rate, while the effect of substitution on the cyclopentadienyl rings on the rate was minor. The observed rates for each mixed-valence monocation in various solvents did not correlate with the reorganization energies, but we did find a significant contribution of the solvent dynamics. The observed rates were considerably higher than those expected on the basis of the Sumi-Marcus-Nalder model in which the solvents were regarded as dielectric continua. The slope of the logarithm plot of the pre-exponential factors in various solvents for each mixed-valence monocation versus the inverse of the longitudinal dielectric relaxation times of the solvents was significantly smaller than unity, and the slope for DFA(+) was larger than those for BFC(+), I(2)BFC(+), and Et(2)BFC(+). These results were ascribed to a partial contribution of the dielectric friction to the dynamics along the solvent coordinate; the extent of the contribution decreased with a reduction in the ET distance. For the dynamics along the solvent coordinate of the ET reactions in methanol, the observed rates indicated an important contribution by the minor dielectric relaxation components with faster relaxation times, rather than the major component with an extraordinarily long relaxation time.

  4. Effect of the Solvent Temperatures on Dynamics of Serine Protease Proteinase K.

    PubMed

    Sang, Peng; Yang, Qiong; Du, Xing; Yang, Nan; Yang, Li-Quan; Ji, Xing-Lai; Fu, Yun-Xin; Meng, Zhao-Hui; Liu, Shu-Qun

    2016-01-01

    To obtain detailed information about the effect of the solvent temperatures on protein dynamics, multiple long molecular dynamics (MD) simulations of serine protease proteinase K with the solute and solvent coupled to different temperatures (either 300 or 180 K) have been performed. Comparative analyses demonstrate that the internal flexibility and mobility of proteinase K are strongly dependent on the solvent temperatures but weakly on the protein temperatures. The constructed free energy landscapes (FELs) at the high solvent temperatures exhibit a more rugged surface, broader spanning range, and higher minimum free energy level than do those at the low solvent temperatures. Comparison between the dynamic hydrogen bond (HB) numbers reveals that the high solvent temperatures intensify the competitive HB interactions between water molecules and protein surface atoms, and this in turn exacerbates the competitive HB interactions between protein internal atoms, thus enhancing the conformational flexibility and facilitating the collective motions of the protein. A refined FEL model was proposed to explain the role of the solvent mobility in facilitating the cascade amplification of microscopic motions of atoms and atomic groups into the global collective motions of the protein. PMID:26907253

  5. Effect of the Solvent Temperatures on Dynamics of Serine Protease Proteinase K

    PubMed Central

    Sang, Peng; Yang, Qiong; Du, Xing; Yang, Nan; Yang, Li-Quan; Ji, Xing-Lai; Fu, Yun-Xin; Meng, Zhao-Hui; Liu, Shu-Qun

    2016-01-01

    To obtain detailed information about the effect of the solvent temperatures on protein dynamics, multiple long molecular dynamics (MD) simulations of serine protease proteinase K with the solute and solvent coupled to different temperatures (either 300 or 180 K) have been performed. Comparative analyses demonstrate that the internal flexibility and mobility of proteinase K are strongly dependent on the solvent temperatures but weakly on the protein temperatures. The constructed free energy landscapes (FELs) at the high solvent temperatures exhibit a more rugged surface, broader spanning range, and higher minimum free energy level than do those at the low solvent temperatures. Comparison between the dynamic hydrogen bond (HB) numbers reveals that the high solvent temperatures intensify the competitive HB interactions between water molecules and protein surface atoms, and this in turn exacerbates the competitive HB interactions between protein internal atoms, thus enhancing the conformational flexibility and facilitating the collective motions of the protein. A refined FEL model was proposed to explain the role of the solvent mobility in facilitating the cascade amplification of microscopic motions of atoms and atomic groups into the global collective motions of the protein. PMID:26907253

  6. Effect of the Solvent Temperatures on Dynamics of Serine Protease Proteinase K.

    PubMed

    Sang, Peng; Yang, Qiong; Du, Xing; Yang, Nan; Yang, Li-Quan; Ji, Xing-Lai; Fu, Yun-Xin; Meng, Zhao-Hui; Liu, Shu-Qun

    2016-02-19

    To obtain detailed information about the effect of the solvent temperatures on protein dynamics, multiple long molecular dynamics (MD) simulations of serine protease proteinase K with the solute and solvent coupled to different temperatures (either 300 or 180 K) have been performed. Comparative analyses demonstrate that the internal flexibility and mobility of proteinase K are strongly dependent on the solvent temperatures but weakly on the protein temperatures. The constructed free energy landscapes (FELs) at the high solvent temperatures exhibit a more rugged surface, broader spanning range, and higher minimum free energy level than do those at the low solvent temperatures. Comparison between the dynamic hydrogen bond (HB) numbers reveals that the high solvent temperatures intensify the competitive HB interactions between water molecules and protein surface atoms, and this in turn exacerbates the competitive HB interactions between protein internal atoms, thus enhancing the conformational flexibility and facilitating the collective motions of the protein. A refined FEL model was proposed to explain the role of the solvent mobility in facilitating the cascade amplification of microscopic motions of atoms and atomic groups into the global collective motions of the protein.

  7. Solvent cleaning system and method for removing contaminants from solvent used in resin recycling

    DOEpatents

    Bohnert, George W.; Hand, Thomas E.; DeLaurentiis, Gary M.

    2009-01-06

    A two step solvent and carbon dioxide based system that produces essentially contaminant-free synthetic resin material and which further includes a solvent cleaning system for periodically removing the contaminants from the solvent so that the solvent can be reused and the contaminants can be collected and safely discarded in an environmentally safe manner.

  8. Solute-solvent and solvent-solvent interactions in the preferential solvation of 4-[4-(dimethylamino)styryl]-1-methylpyridinium iodide in 24 binary solvent mixtures

    NASA Astrophysics Data System (ADS)

    Bevilaqua, Tharly; Gonçalves, Thaini F.; Venturini, Cristina de G.; Machado, Vanderlei G.

    2006-11-01

    The molar transition energy ( ET) polarity values for the dye 4-[4-(dimethylamino)styryl]-1-methylpyridinium iodide were collected in binary mixtures comprising a hydrogen-bond accepting (HBA) solvent (acetone, acetonitrile, dimethyl sulfoxide (DMSO), and N, N-dimethylformamide (DMF)) and a hydrogen-bond donating (HBD) solvent (water, methanol, ethanol, propan-2-ol, and butan-1-ol). Data referring to mixtures of water with alcohols were also analyzed. These data were used in the study of the preferential solvation of the probe, in terms of both solute-solvent and solvent-solvent interactions. These latter interactions are of importance in explaining the synergistic behavior observed for many mixed solvent systems. All data were successfully fitted to a model based on solvent-exchange equilibria. The ET values of the dye dissolved in the solvents show that the position of the solvatochromic absorption band of the dye is dependent on the medium polarity. The solvation of the dye in HBA solvents occurs with a very important contribution from ion-dipole interactions. In HBD solvents, the hydrogen bonding between the dimethylamino group in the dye and the OH group in the solvent plays an important role in the solvation of the dye. The interaction of the hydroxylic solvent with the other component in the mixture can lead to the formation of hydrogen-bonded complexes, which solvate the dye using a lower polar moiety, i.e. alkyl groups in the solvents. The dye has a hydrophobic nature and a dimethylamino group with a minor capability for hydrogen bonding with the medium in comparison with the phenolate group present in Reichardt's pyridiniophenolate. Thus, the probe is able to detect solvent-solvent interactions, which are implicit to the observed synergistic behavior.

  9. Probing the coordination environment of Ti(3+) ions coordinated to nitrogen-containing Lewis bases.

    PubMed

    Morra, E; Maurelli, S; Chiesa, M; Van Doorslaer, S

    2015-08-28

    Multi-frequency continuous-wave and pulsed EPR techniques are employed to investigate the coordination of nitrogen-containing ligands to Ti(3+)-chloro complexes. Frozen solutions of TiCl3 and TiCl3(Py)3 dissolved in nitrogen-containing solvents have been investigated together with the TiCl3(Py)3 solid-state complex. For these different systems, the hyperfine and nuclear quadrupole data of Ti(3+)-bound (14)N nuclei are reported and discussed in the light of DFT computations, allowing for a detailed description of the microscopic structure of these systems.

  10. The weak scale from BBN

    NASA Astrophysics Data System (ADS)

    Hall, Lawrence J.; Pinner, David; Ruderman, Joshua T.

    2014-12-01

    The measured values of the weak scale, v, and the first generation masses, m u, d, e , are simultaneously explained in the multiverse, with all these parameters scanning independently. At the same time, several remarkable coincidences are understood. Small variations in these parameters away from their measured values lead to the instability of hydrogen, the instability of heavy nuclei, and either a hydrogen or a helium dominated universe from Big Bang Nucleosynthesis. In the 4d parameter space of ( m u , m d , m e , v), catastrophic boundaries are reached by separately increasing each parameter above its measured value by a factor of (1.4, 1.3, 2.5, ˜ 5), respectively. The fine-tuning problem of the weak scale in the Standard Model is solved: as v is increased beyond the observed value, it is impossible to maintain a significant cosmological hydrogen abundance for any values of m u, d, e that yield both hydrogen and heavy nuclei stability.

  11. Weak antilocalisation in topological insulators

    NASA Astrophysics Data System (ADS)

    Bi, Xintao; Hankiewicz, Ewelina; Culcer, Dimitrie

    2014-03-01

    Topological insulators (TI) have changed our understanding of insulating behaviour. They are insulators in the bulk but conducting along their surfaces due to spin-orbit interaction. Much of the recent research focuses on overcoming the transport bottleneck, the fact that surface state transport is overwhelmed by bulk transport stemming from unintentional doping. The key to overcoming this bottleneck is identifying unambiguous signatures of surface state transport. This talk will discuss one such signature, which is manifest in the coherent backscattering of electrons. Due to strong spin-orbit coupling in TI one expects to observe weak antilocalisation rather than weak localisation, meaning that coherent backscattering increases the electrical conductivity. The features of this effect, however, are rather subtle, because in TI the impurities have strong spin-orbit coupling as well. I will show that spin-orbit coupled impurities introduce an additional time scale, which is expected to be shorter than the dephasing time, and the resulting conductivity has a logarithmic dependence on the carrier density, a behaviour hitherto unknown in 2D electron systems. The result we predict is observable experimentally and would provide a smoking gun test of surface transport.

  12. Weak lensing and cosmological investigation

    NASA Astrophysics Data System (ADS)

    Acquaviva, Viviana

    2005-03-01

    In the last few years the scientific community has been dealing with the challenging issue of identifying the dark energy component. We regard weak gravitational lensing as a brand new, and extremely important, tool for cosmological investigation in this field. In fact, the features imprinted on the Cosmic Microwave Background radiation by the lensing from the intervening distribution of matter represent a pretty unbiased estimator, and can thus be used for putting constraints on different dark energy models. This is true in particular for the magnetic-type B-modes of CMB polarization, whose unlensed spectrum at large multipoles (l ~= 1000) is very small even in presence of an amount of gravitational waves as large as currently allowed by the experiments: therefore, on these scales the lensing phenomenon is the only responsible for the observed power, and this signal turns out to be a faithful tracer of the dark energy dynamics. We first recall the formal apparatus of the weak lensing in extended theories of gravity, introducing the physical observables suitable to cast the bridge between lensing and cosmology, and then evaluate the amplitude of the expected effect in the particular case of a Non-Minimally-Coupled model, featuring a quadratic coupling between quintessence and Ricci scalar.

  13. Batch extracting process using magneticparticle held solvents

    DOEpatents

    Nunez, Luis; Vandergrift, George F.

    1995-01-01

    A process for selectively removing metal values which may include catalytic values from a mixture containing same, wherein a magnetic particle is contacted with a liquid solvent which selectively dissolves the metal values to absorb the liquid solvent onto the magnetic particle. Thereafter the solvent-containing magnetic particles are contacted with a mixture containing the heavy metal values to transfer metal values into the solvent carried by the magnetic particles, and then magnetically separating the magnetic particles. Ion exchange resins may be used for selective solvents.

  14. Aminosilicone solvents for CO(2) capture.

    PubMed

    Perry, Robert J; Grocela-Rocha, Teresa A; O'Brien, Michael J; Genovese, Sarah; Wood, Benjamin R; Lewis, Larry N; Lam, Hubert; Soloveichik, Grigorii; Rubinsztajn, Malgorzata; Kniajanski, Sergei; Draper, Sam; Enick, Robert M; Johnson, J Karl; Xie, Hong-bin; Tapriyal, Deepak

    2010-08-23

    This work describes the first report of the use of an aminosilicone solvent mix for the capture of CO(2). To maintain a liquid state, a hydroxyether co-solvent was employed which allowed enhanced physisorption of CO(2) in the solvent mixture. Regeneration of the capture solvent system was demonstrated over 6 cycles and absorption isotherms indicate a 25-50 % increase in dynamic CO(2) capacity over 30 % MEA. In addition, proof of concept for continuous CO(2) absorption was verified. Additionally, modeling to predict heats of reaction of aminosilicone solvents with CO(2) was in good agreement with experimental results.

  15. One-nucleon-induced nonmesonic hypernuclear decay in laboratory coordinates

    SciTech Connect

    Galeao, A. P.; Barbero, C.; De Conti, C.; Krmpotic, F.

    2013-05-06

    We present a formalism for the computation of one-nucleon-induced nonmesonic weak hypernuclear decay rates in laboratory coordinates, within an independent-particle shell model framework, with a view to its generalization to the case of two-nucleon-induced transitions.

  16. Framework for coordination of activities in dynamic situations

    NASA Astrophysics Data System (ADS)

    Franke, Jörn; Charoy, François; El Khoury, Paul

    2013-02-01

    Recent disasters, such as Hurricane Katrina in 2005, have shown several issues for the coordination of human activities in these dynamic situations. Contemporary tools for the coordination used in the disaster response, such as e-mail, Whiteboards or phones, only allow for unstructured coordination, which can cause coordination problems. Hence, we discuss about the current information systems for coordinating the activities in a structured manner and identify their weaknesses in the context of a process modelling effort conducted together with experienced disaster managers. Afterwards, we propose a framework for coordination of activities in dynamic situations. The framework presented in this paper has been implemented as an extension to an open collaboration service. This shows how it can be used in the context of other tools required for disaster response management, such as maps, pictures or videos of the situation. The work described here is the foundation for enabling inter-organisational coordination of activities relevant in other domains, e.g. enterprise support processes, production processes or distributed software development projects. Furthermore, comments by disaster managers show that the concepts are relevant for their work. The expected impact is a more effective and efficient coordination of human activities in dynamic situations by structuring what needs to be coordinated.

  17. Coordination chemistry and solution structure of Fe(II)-peplomycin. Two possible coordination geometries.

    PubMed

    Li, Yang; Lehmann, Teresa

    2012-06-01

    The solution structure of Fe(II)-peplomycin was determined from NMR data collected for this molecule. As found previously for Fe(II)- and Co(II)-bound bleomycin; the coordination sphere of the metal is composed of the primary and secondary amines in β-aminoalanine, the pyrimidine and imidazole rings in the pyrimidinylpropionamide, and β-hydroxyhistidine moieties, respectively, the amine nitrogen in β-hydroxyhistidine, and either the carbamoyl group in mannose or a solvent molecule. The two most discussed coordination geometries for the aforementioned ligands in metallo-bleomycins have been tested against the NMR data generated for Fe(II)-peplomycin. The interpretation of the experimental evidence obtained through molecular dynamics indicates that both geometries are equally likely in solution for this compound in the absence of DNA, but arguments are offered to explain why one of these geometries is preferred in the presence of DNA.

  18. Heterogeneous, weakly coupled map lattices

    NASA Astrophysics Data System (ADS)

    Sotelo Herrera, M.a. Dolores; San Martín, Jesús; Porter, Mason A.

    2016-07-01

    Coupled map lattices (CMLs) are often used to study emergent phenomena in nature. It is typically assumed (unrealistically) that each component is described by the same map, and it is important to relax this assumption. In this paper, we characterize periodic orbits and the laminar regime of type-I intermittency in heterogeneous weakly coupled map lattices (HWCMLs). We show that the period of a cycle in an HWCML is preserved for arbitrarily small coupling strengths even when an associated uncoupled oscillator would experience a period-doubling cascade. Our results characterize periodic orbits both near and far from saddle-node bifurcations, and we thereby provide a key step for examining the bifurcation structure of heterogeneous CMLs.

  19. 7 CFR 51.894 - Weak.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Standards for Grades of Table Grapes (European or Vinifera Type) 1 Definitions § 51.894 Weak. Weak means... content, inferior flavor, or are of poor keeping quality....

  20. 7 CFR 51.894 - Weak.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... Standards for Grades of Table Grapes (European or Vinifera Type) 1 Definitions § 51.894 Weak. Weak means that individual berries are somewhat translucent, watery and soft, may have relatively low...

  1. 7 CFR 51.894 - Weak.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... Standards for Grades of Table Grapes (European or Vinifera Type) 1 Definitions § 51.894 Weak. Weak means that individual berries are somewhat translucent, watery and soft, may have relatively low...

  2. A solvent-controlled switch of manganese complex assemblies with a beta-diketonate-based ligand.

    PubMed

    Aromí, Guillem; Gamez, Patrick; Roubeau, Olivier; Berzal, Paula Carrero; Kooijman, Huub; Spek, Anthony L; Driessen, Willem L; Reedijk, Jan

    2002-07-15

    The coordination properties of the new polynucleating ligand H(3)L1 (1,3-bis(3-oxo-3-phenylpropionyl)-2-hydroxy-5-methylbenzene) with Mn(II/III) are described. Depending on the solvent used, the reaction of H(3)L1 with Mn(OAc)(2) yields either of the two new multinuclear assemblies [Mn(2)(HL1)(2)(py)(4)] (1) and [Mn(3)(HL1)(3)] (2), as revealed by X-ray crystallography. The structure of 2 is remarkable in that it shows a unique asymmetric triple-stranded helicate. Complexes 1 and 2 can be interconverted by controlling the solvent of the reaction system, and therefore, this ensemble constitutes an interesting externally addressable switch. In the presence of Mn(III)/pyridine, partial degradation of H(3)L1 occurs via oxidative cleavage, and the new complex [Mn(2)(L2)(2)(py)(4)] (3) is formed. The crystal structure of this complex has shown the fully deprotonated form of the new donor H(3)L2 (3-(3-oxo-3-phenylpropionyl)-5-methylsalicylic acid). From the same reaction, the Mn(II) complex 1 is also obtained. A rational synthesis of H(3)L2 is reported, and this has been used to prepare 3 in high yields, directly from its components. Variable-temperature magnetic susceptibility (chi(m)) measurements were performed on complexes 1-3 under a magnetic field of 1 kG. The data for each complex were fit to the appropriate chi(m) vs T theoretical equation, respectively. In 1, the Mn(II) ions are uncoupled, with g = 2.01. The data from 2 were fit by assuming the presence of an exchange coupled Mn(II)...Mn(II) pair next to a magnetically isolated Mn(II) center. The fit gave J = -2.75 cm(-1), g(12) = 1.97, and g(3) = 1.92, respectively. In 3, two models fit the experimental data. In the most satisfactory, the Mn(III) ions are coupled antiferromagnetically with J = -1.48 cm(-1) and g = 1.98 and a term for weak ferromagnetic intermolecular exchange is included with zJ' = 0.39 cm(-1). The other model contemplates the presence of two uncoupled zero field split Mn(III) ions.

  3. Advanced integrated solvent extraction systems

    SciTech Connect

    Horwitz, E.P.; Dietz, M.L.; Leonard, R.A.

    1997-10-01

    Advanced integrated solvent extraction systems are a series of novel solvent extraction (SX) processes that will remove and recover all of the major radioisotopes from acidic-dissolved sludge or other acidic high-level wastes. The major focus of this effort during the last 2 years has been the development of a combined cesium-strontium extraction/recovery process, the Combined CSEX-SREX Process. The Combined CSEX-SREX Process relies on a mixture of a strontium-selective macrocyclic polyether and a novel cesium-selective extractant based on dibenzo 18-crown-6. The process offers several potential advantages over possible alternatives in a chemical processing scheme for high-level waste treatment. First, if the process is applied as the first step in chemical pretreatment, the radiation level for all subsequent processing steps (e.g., transuranic extraction/recovery, or TRUEX) will be significantly reduced. Thus, less costly shielding would be required. The second advantage of the Combined CSEX-SREX Process is that the recovered Cs-Sr fraction is non-transuranic, and therefore will decay to low-level waste after only a few hundred years. Finally, combining individual processes into a single process will reduce the amount of equipment required to pretreat the waste and therefore reduce the size and cost of the waste processing facility. In an ongoing collaboration with Lockheed Martin Idaho Technology Company (LMITCO), the authors have successfully tested various segments of the Advanced Integrated Solvent Extraction Systems. Eichrom Industries, Inc. (Darien, IL) synthesizes and markets the Sr extractant and can supply the Cs extractant on a limited basis. Plans are under way to perform a test of the Combined CSEX-SREX Process with real waste at LMITCO in the near future.

  4. Arene Selectivity by a Flexible Coordination Polymer Host.

    PubMed

    Wright, James S; Vitórica-Yrezábal, Iñigo J; Thompson, Stephen P; Brammer, Lee

    2016-09-01

    The coordination polymers [Ag4 (O2 CCF3 )4 (phen)3 ]⋅ phen⋅arene (1⋅phen⋅arene) (phen=phenazine; arene=toluene, p-xylene or benzene) have been synthesised from the solution phase in a series of arene solvents and crystallographically characterised. By contrast, analogous syntheses from o-xylene and m-xylene as the solvent yield the solvent-free coordination polymer [Ag4 (O2 CCF3 )4 (phen)2 ] (2). Toluene, p-xylene and benzene have been successfully used in mixed-arene syntheses to template the formation of coordination polymers 1⋅phen⋅arene, which incorporate o- or m-xylene. The selectivity of 1⋅phen⋅arene for the arene guests was determined, through pairwise competition experiments, to be p-xylene>toluene≈benzene>o-xylene>m-xylene. The largest selectivity coefficient was determined as 14.2 for p-xylene:m-xylene and the smallest was 1.0 for toluene:benzene. PMID:27483388

  5. Arene Selectivity by a Flexible Coordination Polymer Host.

    PubMed

    Wright, James S; Vitórica-Yrezábal, Iñigo J; Thompson, Stephen P; Brammer, Lee

    2016-09-01

    The coordination polymers [Ag4 (O2 CCF3 )4 (phen)3 ]⋅ phen⋅arene (1⋅phen⋅arene) (phen=phenazine; arene=toluene, p-xylene or benzene) have been synthesised from the solution phase in a series of arene solvents and crystallographically characterised. By contrast, analogous syntheses from o-xylene and m-xylene as the solvent yield the solvent-free coordination polymer [Ag4 (O2 CCF3 )4 (phen)2 ] (2). Toluene, p-xylene and benzene have been successfully used in mixed-arene syntheses to template the formation of coordination polymers 1⋅phen⋅arene, which incorporate o- or m-xylene. The selectivity of 1⋅phen⋅arene for the arene guests was determined, through pairwise competition experiments, to be p-xylene>toluene≈benzene>o-xylene>m-xylene. The largest selectivity coefficient was determined as 14.2 for p-xylene:m-xylene and the smallest was 1.0 for toluene:benzene.

  6. SOLVENT EXTRACTION PROCESS FOR PLUTONIUM

    DOEpatents

    Seaborg, G.T.

    1959-04-14

    The separation of plutonium from aqueous inorganic acid solutions by the use of a water immiscible organic extractant liquid is described. The plutonium must be in the oxidized state, and the solvents covered by the patent include nitromethane, nitroethane, nitropropane, and nitrobenzene. The use of a salting out agents such as ammonium nitrate in the case of an aqueous nitric acid solution is advantageous. After contacting the aqueous solution with the organic extractant, the resulting extract and raffinate phases are separated. The plutonium may be recovered by any suitable method.

  7. Chronic care coordination.

    PubMed

    Peters, Steve G; Bunkers, Kari S

    2015-10-01

    Chronic care management describes the services provided to patients with two or more chronic conditions that pose risks of exacerbation, clinical deterioration, or death. These services extend beyond the typical face-to-face office visit and require coordination and oversight by a physician or other qualified health-care professional to maintain and modify as necessary a comprehensive and multidisciplinary plan of care. New codes for 2015 describe chronic care management services per calendar month. While the new services acknowledge the role and importance of coordination by primary care providers, they are also appropriate for specialists who oversee the management of all of the chronic conditions of a patient and provide access, education, care coordination, communication, and health information exchange with other providers.

  8. FT-Raman spectroscopy study of solvent-in-salt electrolytes

    NASA Astrophysics Data System (ADS)

    Liumin, Suo; Fang, Zheng; Yong-Sheng, Hu; Liquan, Chen

    2016-01-01

    Cation-anion interaction with different ratios of salt to solvent is investigated by FT-Raman spectroscopy. The fitting result of the C-N-C bending vibration manifests that the cation-anion coordination structure changes tremendously with the variation of salt concentration. It is well known that lithium-ion transport in ultrahigh salt concentration electrolyte is dramatically different from that in dilute electrolyte, due to high viscosity and strong cation-anion interaction. In ultrahigh salt concentrated “solvent-in-salt” electrolyte (SIS-7#), we found, on one hand, that the cation and anion in the solution mainly formed cation-anion pairs with a high Li+ coordination number (≥ 1), including intimate ion pairs (20.1%) and aggregated ion pairs (79.9%), which not only cause low total ionic conductivity but also cause a high lithium transference number (0.73). A possible lithium transport mechanism is proposed: in solvent-in-salt electrolytes, lithium ions’ direct movement presumably depends on Li-ion exchange between aggregated ion pairs and solvent molecules, which repeats a dissolving and re-complexing process between different oxygen groups of solvent molecules. Project supported by the National Basic Research Program of China (Grant No. 2014CB932300), the National Natural Science Foundation of China (Grant Nos. 51222210, 51472268, and 11234013), and the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No. XDA09010300).

  9. Colorimetric Humidity and Solvent Recognition Based on a Cation-Exchange Clay Mineral Incorporating Nickel(II)-Chelate Complexes.

    PubMed

    Hosokawa, Hitoshi; Mochida, Tomoyuki

    2015-12-01

    Solvatochromic nickel(II) complexes with diketonato and diamine ligands were incorporated into a saponite clay by ion exchange, and their colorimetric humidity- and solvent-recognition properties were investigated. These powders exhibit color change from red to blue-green depending on humidity, and the detection range can be controlled by modifying the metal complex. The humidity response takes advantage of the humidity-dependent water content in clay and the coordination of water molecules to the metal complex in equilibrium. The addition of organic solvents to the powders causes a color change to occur, varying from red to blue-green depending on the donor number of the solvent, thereby enabling solvent recognition. In the clay, the affinity of less sterically hindered complexes to water or solvent molecules is decreased compared with that in solution because the cationic complexes interact with the anionic layers in the clay. Incorporating diethylene glycol into the materials produced thermochromic powders.

  10. Assembly of Cerium(III) 2,2'-Bipyridine-5,5'-dicarboxylate-based Metal–Organic Frameworks by Solvent Tuning

    SciTech Connect

    Ayhan, Ozan; Malaestean, Iurie L.; Ellern, Arkady; van Leusen, Jan; Baca, Svetlana G.; Kögerler, Paul

    2014-07-02

    Two cerium(III) 2,2'-bipyridine-5,5'-dicarboxylate-based 3D coordination networks highlight the ability of CeIII ions to adopt different coordination environments upon subtle changes to the reaction conditions, producing metal-organic frameworks that integrate varying crystal solvent contents.

  11. Versatile Structure-directing Roles of Deep Eutectic Solvents and Their Implication in Generation of Porosity and Open Metal Sites for Gas Storage**

    PubMed Central

    Zhang, Jian; Wu, Tao; Chen, Shumei; Feng, Pingyun; Bu, Xianhui

    2009-01-01

    Trap it in and burn it out: the deep eutectic solvent provides a versatile route for the creation of highly stable porous frameworks encapsulating neutral coordinating ligand molecule, which can escape intact from the pore upon heating to directly become crystals, leaving behind permanent porosity and coordinatively unsaturated metal sites with potential applications in gas storage and catalysis. PMID:19343752

  12. Deterministic weak localization in periodic structures.

    PubMed

    Tian, C; Larkin, A

    2005-12-01

    In some perfect periodic structures classical motion exhibits deterministic diffusion. For such systems we present the weak localization theory. As a manifestation for the velocity autocorrelation function a universal power law decay is predicted to appear at four Ehrenfest times. This deterministic weak localization is robust against weak quenched disorders, which may be confirmed by coherent backscattering measurements of periodic photonic crystals.

  13. On projective coordinate spaces

    NASA Astrophysics Data System (ADS)

    Ćiftçi, Süleyman; Erdoǧan, Fatma Özen

    2015-09-01

    In the present study, an (n+1)-dimensional module over the local ring K = Mmm(ℝ) is constructed. Further, an n- dimensional projective coordinate space over this module is constructed by the help of equivalence classes. The points and lines of this space are determined and the points are classified. Finally, for a 3-dimensional projective coordinate space, the incidence matrix for a line that goes through the given points and also all points of a line given with the incidence matrix are found by the use of Maple commands.

  14. Coordinate Standard Measurement Development

    SciTech Connect

    Hanshaw, R.A.

    2000-02-18

    A Shelton Precision Interferometer Base, which is used for calibration of coordinate standards, was improved through hardware replacement, software geometry error correction, and reduction of vibration effects. Substantial increases in resolution and reliability, as well as reduction in sampling time, were achieved through hardware replacement; vibration effects were reduced substantially through modification of the machine component dampening and software routines; and the majority of the machine's geometry error was corrected through software geometry error correction. Because of these modifications, the uncertainty of coordinate standards calibrated on this device has been reduced dramatically.

  15. The solvent component of macromolecular crystals

    PubMed Central

    Weichenberger, Christian X.; Afonine, Pavel V.; Kantardjieff, Katherine; Rupp, Bernhard

    2015-01-01

    The mother liquor from which a biomolecular crystal is grown will contain water, buffer molecules, native ligands and cofactors, crystallization precipitants and additives, various metal ions, and often small-molecule ligands or inhibitors. On average, about half the volume of a biomolecular crystal consists of this mother liquor, whose components form the disordered bulk solvent. Its scattering contributions can be exploited in initial phasing and must be included in crystal structure refinement as a bulk-solvent model. Concomitantly, distinct electron density originating from ordered solvent components must be correctly identified and represented as part of the atomic crystal structure model. Herein, are reviewed (i) probabilistic bulk-solvent content estimates, (ii) the use of bulk-solvent density modification in phase improvement, (iii) bulk-solvent models and refinement of bulk-solvent contributions and (iv) modelling and validation of ordered solvent constituents. A brief summary is provided of current tools for bulk-solvent analysis and refinement, as well as of modelling, refinement and analysis of ordered solvent components, including small-molecule ligands. PMID:25945568

  16. Reducing Systematic Error in Weak Lensing Cluster Surveys

    NASA Astrophysics Data System (ADS)

    Utsumi, Yousuke; Miyazaki, Satoshi; Geller, Margaret J.; Dell'Antonio, Ian P.; Oguri, Masamune; Kurtz, Michael J.; Hamana, Takashi; Fabricant, Daniel G.

    2014-05-01

    Weak lensing provides an important route toward collecting samples of clusters of galaxies selected by mass. Subtle systematic errors in image reduction can compromise the power of this technique. We use the B-mode signal to quantify this systematic error and to test methods for reducing this error. We show that two procedures are efficient in suppressing systematic error in the B-mode: (1) refinement of the mosaic CCD warping procedure to conform to absolute celestial coordinates and (2) truncation of the smoothing procedure on a scale of 10'. Application of these procedures reduces the systematic error to 20% of its original amplitude. We provide an analytic expression for the distribution of the highest peaks in noise maps that can be used to estimate the fraction of false peaks in the weak-lensing κ-signal-to-noise ratio (S/N) maps as a function of the detection threshold. Based on this analysis, we select a threshold S/N = 4.56 for identifying an uncontaminated set of weak-lensing peaks in two test fields covering a total area of ~3 deg2. Taken together these fields contain seven peaks above the threshold. Among these, six are probable systems of galaxies and one is a superposition. We confirm the reliability of these peaks with dense redshift surveys, X-ray, and imaging observations. The systematic error reduction procedures we apply are general and can be applied to future large-area weak-lensing surveys. Our high-peak analysis suggests that with an S/N threshold of 4.5, there should be only 2.7 spurious weak-lensing peaks even in an area of 1000 deg2, where we expect ~2000 peaks based on our Subaru fields. Based in part on data collected at Subaru Telescope and obtained from the SMOKA, which is operated by the Astronomy Data Center, National Astronomical Observatory of Japan.

  17. Profiling Computing Coordinators.

    ERIC Educational Resources Information Center

    Edwards, Sigrid; Morton, Allan

    The people responsible for managing school computing resources in Australia have become known as Computing Coordinators. To date there has been no large systematic study of the role, responsibilities and characteristics of this position. This paper represents a first attempt to provide information on the functions and attributes of the Computing…

  18. Coordination of hand shape.

    PubMed

    Pesyna, Colin; Pundi, Krishna; Flanders, Martha

    2011-03-01

    The neural control of hand movement involves coordination of the sensory, motor, and memory systems. Recent studies have documented the motor coordinates for hand shape, but less is known about the corresponding patterns of somatosensory activity. To initiate this line of investigation, the present study characterized the sense of hand shape by evaluating the influence of differences in the amount of grasping or twisting force, and differences in forearm orientation. Human subjects were asked to use the left hand to report the perceived shape of the right hand. In the first experiment, six commonly grasped items were arranged on the table in front of the subject: bottle, doorknob, egg, notebook, carton, and pan. With eyes closed, subjects used the right hand to lightly touch, forcefully support, or imagine holding each object, while 15 joint angles were measured in each hand with a pair of wired gloves. The forces introduced by supporting or twisting did not influence the perceptual report of hand shape, but for most objects, the report was distorted in a consistent manner by differences in forearm orientation. Subjects appeared to adjust the intrinsic joint angles of the left hand, as well as the left wrist posture, so as to maintain the imagined object in its proper spatial orientation. In a second experiment, this result was largely replicated with unfamiliar objects. Thus, somatosensory and motor information appear to be coordinated in an object-based, spatial-coordinate system, sensitive to orientation relative to gravitational forces, but invariant to grasp forcefulness. PMID:21389230

  19. Sex Equity Coordinator's Handbook.

    ERIC Educational Resources Information Center

    Rubenstein, Dorothy; Sillman, Donna

    This guidebook was designed to assist sex equity coordinators in the Los Angeles Community College District in promoting the recruitment, retention, and placement of students in vocational programs that are non-traditional for their sex. The guidebook's first ten chapters present: (1) outlines of relevant legislation and legal guidelines for…

  20. Coordination of Hand Shape

    PubMed Central

    Pesyna, Colin; Pundi, Krishna; Flanders, Martha

    2011-01-01

    The neural control of hand movement involves coordination of the sensory, motor and memory systems. Recent studies have documented the motor coordinates for hand shape, but less is known about the corresponding patterns of somatosensory activity. To initiate this line of investigation, the present study characterized the sense of hand shape by evaluating the influence of differences in the amount of grasping or twisting force, and differences in forearm orientation. Human subjects were asked to use the left hand to report the perceived shape of the right hand. In Experiment 1, six commonly grasped items were arranged on the table in front of the subject: bottle, doorknob, egg, notebook, carton, pan. With eyes closed, subjects used the right hand to lightly touch, forcefully support or imagine holding each object, while 15 joint angles were measured in each hand with a pair of wired gloves. The forces introduced by supporting or twisting did not influence the perceptual report of hand shape, but for most objects, the report was distorted in a consistent manner by differences in forearm orientation. Subjects appeared to adjust the intrinsic joint angles of the left hand, as well as the left wrist posture, so as to maintain the imagined object in its proper spatial orientation. In a second experiment, this result was largely replicated with unfamiliar objects. Thus somatosensory and motor information appear to be coordinated in an object-based, spatial coordinate system, sensitive to orientation relative to gravitational forces, but invariant to grasp forcefulness. PMID:21389230

  1. Block coordination copolymers

    DOEpatents

    Koh, Kyoung Moo; Wong-Foy, Antek G; Matzger, Adam J; Benin, Annabelle I; Willis, Richard R

    2012-11-13

    The present invention provides compositions of crystalline coordination copolymers wherein multiple organic molecules are assembled to produce porous framework materials with layered or core-shell structures. These materials are synthesized by sequential growth techniques such as the seed growth technique. In addition, the invention provides a simple procedure for controlling functionality.

  2. Block coordination copolymers

    DOEpatents

    Koh, Kyoung Moo; Wong-Foy, Antek G.; Matzger, Adam J.; Benin, Annabelle I.; Willis, Richard R.

    2012-12-04

    The present invention provides compositions of crystalline coordination copolymers wherein multiple organic molecules are assembled to produce porous framework materials with layered or core-shell structures. These materials are synthesized by sequential growth techniques such as the seed growth technique. In addition, the invention provides a simple procedure for controlling functionality.

  3. Block coordination copolymers

    DOEpatents

    Koh, Kyoung Moo; Wong-Foy, Antek G; Matzger, Adam J; Benin, Annabelle I; Willis, Richard R

    2014-11-11

    The present invention provides compositions of crystalline coordination copolymers wherein multiple organic molecules are assembled to produce porous framework materials with layered or core-shell structures. These materials are synthesized by sequential growth techniques such as the seed growth technique. In addition, the invention provides a simple procedure for controlling functionality.

  4. Origins of Coordinate Searching.

    ERIC Educational Resources Information Center

    Kilgour, Frederick G.

    1997-01-01

    Reviews the origins of post-coordinate searching and emphasizes that the focal point should be on the searcher, not on the item being indexed. Highlights include the history of the term information retrieval; edge notched punch cards; the "peek-a-boo" system; the Uniterm system; and using computers to search for information. (LRW)

  5. Stabilization of hexa-coordinated P(v) corroles by axial silyloxy groups.

    PubMed

    Chatterjee, Tamal; Lee, Way-Zen; Ravikanth, Mangalampalli

    2016-05-01

    We report the stabilization of the hexa-coordination environment for P(v) corroles by using alkyl/aryl substituted silyloxy groups as axial ligands. The P(v) corroles are highly fluorescent in a hexa-coordination environment compared to in a penta-coordination environment. However, P(v) corroles generally undergo axial ligand dissociation to form a mixture of penta- and hexa-coordinated P(v) corroles in non-coordinating solvents such as toluene, CH2Cl2, CHCl3. The usage of moderately bulkier and electron-donating silyloxy groups helps to restrict the axial ligand dissociation of silyloxy substituted hexa-coordinated P(v) corroles in non-coordinating solvents. The crystal structure confirmed the hexa-coordination geometry for the P(v) corroles. The P(v) corroles strongly absorb and emit in the visible region, with decent quantum yields and singlet state lifetimes. The hexa-coordinated P(v) corroles are highly stable under electrochemical conditions.

  6. Protecting weak measurements against systematic errors

    NASA Astrophysics Data System (ADS)

    Pang, Shengshi; Alonso, Jose Raul Gonzalez; Brun, Todd A.; Jordan, Andrew N.

    2016-07-01

    In this work, we consider the systematic error of quantum metrology by weak measurements under decoherence. We derive the systematic error of maximum likelihood estimation in general to the first-order approximation of a small deviation in the probability distribution and study the robustness of standard weak measurement and postselected weak measurements against systematic errors. We show that, with a large weak value, the systematic error of a postselected weak measurement when the probe undergoes decoherence can be significantly lower than that of a standard weak measurement. This indicates another advantage of weak-value amplification in improving the performance of parameter estimation. We illustrate the results by an exact numerical simulation of decoherence arising from a bosonic mode and compare it to the first-order analytical result we obtain.

  7. Lanthanide-organic complexes based on polyoxometalates: Solvent effect on the luminescence properties

    SciTech Connect

    Tang Qun; Liu Shuxia; Liang Dadong; Ma Fengji; Ren Guojian; Wei Feng; Yang Yuan; Li Congcong

    2012-06-15

    A series of lanthanide-organic complexes based on polyoxometalates (POMs) [Ln{sub 2}(DNBA){sub 4}(DMF){sub 8}][W{sub 6}O{sub 19}] (Ln=La(1), Ce(2), Sm(3), Eu(4), Gd(5); DNBA=3,5-dinitrobenzoate; DMF=N,N-dimethylformamide) has been synthesized. These complexes consist of [W{sub 6}O{sub 19}]{sup 2-} and dimeric [Ln{sub 2}(DNBA){sub 4}(DMF){sub 8}]{sup 2+} cations. The luminescence properties of 4 are measured in solid state and different solutions, respectively. Notably, the emission intensity increases gradually with the increase of solvent permittivity, and this solvent effect can be directly observed by electrospray mass spectrometry (ESI-MS). The analyses of ESI-MS show that the eight coordinated solvent DMF units of dimeric cation are active. They can move away from dimeric cations and exchange with solvent molecules. Although the POM anions escape from 3D supramolecular network, the dimeric state structure of [Ln{sub 2}(DNBA){sub 4}]{sup 2+} remains unchanged in solution. The conservation of red luminescence is attributed to the maintenance of the aggregated state structures of dimeric cations. - Graphical abstract: 3D POMs-based lanthanide-organic complexes performed the solvent effect on the luminescence property. The origin of such solvent effect can be understood and explained on the basis of the existence of coordinated active sites by the studies of ESI-MS. Highlights: Black-Right-Pointing-Pointer The solvent effect on the luminescence property of POMs-based lanthanide-organic complexes. Black-Right-Pointing-Pointer ESI-MS analyses illuminate the correlation between the structure and luminescence property. Black-Right-Pointing-Pointer The dimeric cations have eight active sites of solvent coordination. Black-Right-Pointing-Pointer The aggregated state structure of dimer cation remains unchanged in solution. Black-Right-Pointing-Pointer Luminescence associating with ESI-MS is a new method for investigating the interaction of complex and solvent.

  8. Tokamak coordinate conventions: COCOS

    NASA Astrophysics Data System (ADS)

    Sauter, O.; Medvedev, S. Yu.

    2013-02-01

    Dealing with electromagnetic fields, in particular current and related magnetic fields, yields "natural" physical vector relations in 3-D. However, when it comes to choosing local coordinate systems, the "usual" right-handed systems are not necessarily the best choices, which means that there are several options being chosen. In the magnetic fusion community such a difficulty exists for the choices of the cylindrical and of the toroidal coordinate systems. In addition many codes depend on knowledge of an equilibrium. In particular, the Grad-Shafranov axisymmetric equilibrium solution for tokamak plasmas, ψ, does not depend on the sign of the plasma current Ip nor that of the magnetic field B0. This often results in ill-defined conventions. Moreover the sign, amplitude and offset of ψ are of less importance, since the free sources in the equation depend on the normalized radial coordinate. The signs of the free sources, dp/dψ and dF2/dψ (p being the pressure, ψ the poloidal magnetic flux and F=RBφ), must be consistent to generate the current density profile. For example, RF and CD calculations (Radio Frequency heating and Current Drive) require an exact sign convention in order to calculate a co- or counter-CD component. It is shown that there are over 16 different coordinate conventions. This paper proposes a unique identifier, the COCOS convention, to distinguish between the 16 most-commonly used options. Given the present worldwide efforts towards code integration, the proposed new index COCOS defining uniquely the COordinate COnventionS required as input by a given code or module is particularly useful. As codes use different conventions, it is useful to allow different sign conventions for equilibrium code input and output, equilibrium being at the core of any calculations in magnetic fusion. Additionally, given two different COCOS conventions, it becomes simple to transform between them. The relevant transformations are described in detail.

  9. [Chlorinate solvents natural biodegradation in shallow groundwater].

    PubMed

    He, Jiang-tao; Li, Ye; Liu, Shi; Chen, Hong-han

    2005-03-01

    Chlorinated solvents contaminations are most popular in shallow groundwater. A serious local groundwater contamination of chlorinated solvents is founded in a north city of China during the organic pollution investigation. On the basis of the available data and the determining methods of chlorinated solvents biodegradation in groundwater under natural conditions, research on chlorinated solvents biodegrading potential is carried out. The results show that the ground water environment parameters, Eh and pH of the groundwater, indirect sign of biodegradation, i.e. NO3- changing, and concentration variation of biodegradation intermediate products of PCE and TCE all proved that chlorinated solvents can be degraded by microorganism in groundwater. The results of simulating experiment also reveal that, co-metabolism biodegradation of chlorinated solvent was possible under the groundwater circumstances in this sample. Therefore, admitting there is biotransformation from PCE to TCE can explain the present situation more reasonably.

  10. Solvent signal as an NMR concentration reference.

    PubMed

    Mo, Huaping; Raftery, Daniel

    2008-12-15

    We propose that the NMR solvent signal be utilized as a universal concentration reference because most solvents can be observed by NMR and solvent concentrations can be readily calculated or determined independently. In particular, a highly protonated solvent such as water can serve as a primary concentration standard for its stability, availability, and ease of observation. The potential problems of radiation damping associated with a strong NMR signal can be alleviated by small pulse angle excitation. The solvent signal then can be detected by the NMR receiver with the same efficiency as a dilute analyte. We demonstrated that the analyte's proton concentration can be accurately determined from 4 microM to more than 100 M, referenced by solvent (water) protons of concentrations more than 10 M. The proposed method is robust and indifferent to probe tuning and does not require any additional concentration standard.

  11. A Universe without Weak Interactions

    SciTech Connect

    Harnik, Roni; Kribs, Graham D.; Perez, Gilad

    2006-04-07

    A universe without weak interactions is constructed that undergoes big-bang nucleosynthesis, matter domination, structure formation, and star formation. The stars in this universe are able to burn for billions of years, synthesize elements up to iron, and undergo supernova explosions, dispersing heavy elements into the interstellar medium. These definitive claims are supported by a detailed analysis where this hypothetical ''Weakless Universe'' is matched to our Universe by simultaneously adjusting Standard Model and cosmological parameters. For instance, chemistry and nuclear physics are essentially unchanged. The apparent habitability of the Weakless Universe suggests that the anthropic principle does not determine the scale of electroweak breaking, or even require that it be smaller than the Planck scale, so long as technically natural parameters may be suitably adjusted. Whether the multi-parameter adjustment is realized or probable is dependent on the ultraviolet completion, such as the string landscape. Considering a similar analysis for the cosmological constant, however, we argue that no adjustments of other parameters are able to allow the cosmological constant to raise up even remotely close to the Planck scale while obtaining macroscopic structure. The fine-tuning problems associated with the electroweak breaking scale and the cosmological constant therefore appear to be qualitatively different from the perspective of obtaining a habitable universe.

  12. Weak Turbulence in Radiation Belts

    NASA Astrophysics Data System (ADS)

    Ganguli, Gurudas; Crabtree, Chris; Rudakov, Leonid

    2015-11-01

    Weak turbulence plays a significant role in space plasma dynamics. Induced nonlinear scattering dominates the evolution in the low-beta isothermal radiation belt plasmas and affects the propagation characteristics of waves. As whistler waves propagate away from the earth they are scattered in the magnetosphere such that their trajectories are turned earthward where they are reflected back towards the magnetosphere. Repeated scattering and reflection of the whistlers establishes a cavity in which the wave energy can be maintained for a long duration with, on average, a smaller wave-normal angle. Consequently, the cyclotron resonance time for the trapped energetic electrons increases, leading to an enhanced pitch-angle scattering rate. Enhanced pitch-angle scattering lowers the lifetime of the energetic electron population. Also, pitch-angle scattering of the trapped population in the cavity with a loss cone distribution amplifies the whistler waves, which in turn promotes a more rapid precipitation through a positive feedback mechanism. Typical storm-pumped radiation belt parameters and laboratory experiments will be used to elucidate this phenomenon Work supported by NRL Base Funds.

  13. Weak Turbulence in Radiation Belts

    NASA Astrophysics Data System (ADS)

    Ganguli, G.; Crabtree, C. E.; Rudakov, L.

    2015-12-01

    Weak turbulence plays a significant role in space plasma dynamics. Induced nonlinear scattering dominates the evolution in the low-beta isothermal radiation belt plasmas and affects the propagation characteristics of waves. As whistler waves propagate away from the earth they are scattered in the magnetosphere such that their trajectories are turned earthward where they are reflected back towards the magnetosphere. Repeated scattering and reflection of the whistlers establishes a cavity in which the wave energy can be maintained for a long duration with, on average, a smaller wave-normal angle. Consequently, the cyclotron resonance time for the trapped energetic electrons increases, leading to an enhanced pitch-angle scattering rate. Enhanced pitch-angle scattering lowers the lifetime of the energetic electron population. Also, pitch-angle scattering of the trapped population in the cavity with a loss cone distribution amplifies the whistler waves, which in turn promotes a more rapid precipitation through a positive feedback mechanism. Typical storm-pumped radiation belt parameters and laboratory experiments will be used to elucidate this phenomenon.

  14. Aryne Compatible Solvents are not Always Innocent.

    PubMed

    Suh, Sung-Eun; Chenoweth, David M

    2016-08-19

    Arynes are important and versatile intermediates in a variety of transformations. Commonly used solvents for aryne chemistry include acetonitrile and dichloromethane. Although rarely reported, the reactive nature of aryne intermediates makes them prone to side reactions, which sometimes involve solvent participation. Acetonitrile and dichloromethane are not always innocent solvents and can participate in aryne-based reactions. These results are presented in the context of ongoing mechanistic investigations of the triple aryne-tetrazine reaction. PMID:27486792

  15. Molecular accessibility in solvent swelled coals. Quarterly report, [September--November, 1993

    SciTech Connect

    Kispert, L.D.

    1993-11-01

    This quarter, experiments were performed on the use of binary swelling solvents in molecular accessibility in coal conversion. These experiments consisted of accessibility measurements of spin probe VII (TEMPAMINE) in Toluene swelled Illinois No. 6 APCS coal. The toluene was spiked with amounts of pyridine which ranged in concentration from 500 ppm to 10%. The experiments were done in triplicate to gain information about the experimental error involved in the procedure. It was shown that oscillations occur in the concentration of spin probe retained as the amount of pyridine that is added to the swelling solvent is increased. These oscillations decrease in intensity as the concentration of pyridine in the solvent solution is increased up to 2% pyridine (0.2mLs pyridine in 10mLs toluene). From a 2% pyridine concentration to a 5% concentration, there is no significant change in the retention of spin probe VII. An increase in retention is observed when the concentration of pyridine is increased to 6% and 7% successively, followed by a large decrease at 8% and 9% pyridine. The largest changes in spin probe retention are observed for concentrations of pyridine less than 0.5%. A three fold increase in spin probe retention is observed upon the addition of 500 ppm pyridine in the toluene swelling solvent, which indicates that small amounts of a strong swelling solvent could be used to improve molecular accessibility 91% in coals swelled in an otherwise weak swelling solvent.

  16. Glycerol and glycerol carbonate as ultraviscous solvents for mixture analysis by NMR

    NASA Astrophysics Data System (ADS)

    Lameiras, Pedro; Boudesocque, Leslie; Mouloungui, Zéphirin; Renault, Jean-Hugues; Wieruszeski, Jean-Michel; Lippens, Guy; Nuzillard, Jean-Marc

    2011-09-01

    NMR of weakly polar analytes in an apolar ultraviscous solvent has recently been proposed for mixture analysis as a pertinent alternative to the DOSY experiment. The present article reports the first use of glycerol and glycerol carbonate as polar solvents for the NMR analysis of a model mixture of dipeptides. This work demonstrates the high potentiality of these solvents for the analysis of mixtures made of polar and potentially bioactive compounds. Medium-sized molecules slowly reorient in glycerol and glycerol carbonate under particular temperature conditions, so that solute resonances may show spin diffusion in NOESY spectra, thus opening the way to mixture analysis. Glycerol and glycerol carbonate have turned out to be ultraviscous solvents of choice for the individualization of four structurally close mixed dipeptides: Leu-Val, Leu-Tyr, Gly-Tyr and Ala-Tyr by means of 1D and 2D NOESY experiments. Selective sample excitation and signal detection were implemented to eliminate the intense proton signals of the non-deuterated solvents. Moreover, the recording of a multiplet selective 2D NOESY-TOCSY has shown that the analytical power of NMR in highly viscous solvents is not limited to the extraction of mixture component 1D subspectra but may also yield some supplementary information about atom connectivity within components.

  17. STUDY OF SOLVENT AND CATALYST INTERACTIONS IN DIRECT COAL LIQUEFACTION

    SciTech Connect

    Michael T. Klein

    2000-01-01

    There are several aspects of the Direct Coal Liquefaction process which are not fully understood and which if better understood might lead to improved yields and conversions. Among these questions are the roles of the catalyst and the solvent. While the solvent is known to act by transfer of hydrogen atoms to the free radicals formed by thermal breakdown of the coal in an uncatalyzed system, in the presence of a solid catalyst as is now currently practiced, the yields and conversions are higher than in an uncatalyzed system. The role of the catalyst in this case is not completely understood. DOE has funded many projects to produce ultrafine and more active catalysts in the expectation that better contact between catalyst and coal might result. This approach has met with limited success probably because mass transfer between two solids in a fluid medium i.e. the catalyst and the coal, is very poor. It is to develop an understanding of the role of the catalyst and solvent in Direct Liquefaction that this project was initiated. Specifically it was of interest to know whether direct contact between the coal and the catalyst was important. By separating the solid catalyst in a stainless steel basket permeable to the solvent but not the coal in the liquefaction reactor, it was shown that the catalyst still maintains a catalytic effect on the liquefaction process. There is apparently transfer of hydrogen atoms from the catalyst through the basket wall to the coal via the solvent. Strong hydrogen donor solvents appear to be more effective in this respect than weak hydrogen donors. It therefore appears that intimate contact between catalyst and coal is not a requirement, and that the role of the catalyst may be to restore the hydrogen donor strength to the solvent as the reaction proceeds. A range of solvents of varying hydrogen donor strength was investigated. Because of the extensive use of thermogravimetric analysis in this laboratory in was noted that the peak

  18. Solvent recovery system provides timely compliance solution

    SciTech Connect

    1996-11-01

    Hoechst Celanese Corp. (Coventry, Rhode Island) faced the challenge of meeting an Environmental Protection Agency (EPA) deadline for solvent recovery within one year. The company also had to ensure that a new solvent recovery system would satisfy Rhode Island state requirements. An initial search for the required technology was fruitless. Finally, MG Industries (Saint Charles, Missouri), an industrial gas supplier, was chosen for the job. Using CRYOSOLV, as the waste stream cools in the cryogenic condenser (heat exchanger), the solvents condense at temperatures below the dewpoint. The recovered solvent can be recycled into the process, while clean gas is vented to the atmosphere.

  19. Process for hydrogenating coal and coal solvents

    DOEpatents

    Tarrer, Arthur R.; Shridharani, Ketan G.

    1983-01-01

    A novel process is described for the hydrogenation of coal by the hydrogenation of a solvent for the coal in which the hydrogenation of the coal solvent is conducted in the presence of a solvent hydrogenation catalyst of increased activity, wherein the hydrogenation catalyst is produced by reacting ferric oxide with hydrogen sulfide at a temperature range of 260.degree. C. to 315.degree. C. in an inert atmosphere to produce an iron sulfide hydrogenation catalyst for the solvent. Optimally, the reaction temperature is 275.degree. C. Alternately, the reaction can be conducted in a hydrogen atmosphere at 350.degree. C.

  20. MCU MATERIALS COMPATIBILITY WITH CSSX SOLVENT

    SciTech Connect

    Fondeur, F

    2006-01-13

    The Modular Caustic-Side Solvent Extraction (CSSX) Unit (MCU) plans to use several new materials of construction not previously used with CSSX solvent. SRNL researchers tested seven materials proposed for service in seal and gasket applications. None of the materials leached detectable amounts of components into the CSSX solvent during 96 hour tests. All are judged acceptable for use based on their effect on the solvent. However, some of the materials adsorbed solvent or changed dimensions during contact with solvent. Consultation with component and material vendors with regard to performance impact and in-use testing of the materials is recommended. Polyetheretherketone (PEEK), a material selected for use in contactor bearing seals, did not gain weight or change dimensions on contact with CSSX solvent. Analysis of the solvent contacted with this material showed no impurities and the standard dispersion test gave acceptable phase separation results. The material contains a leachable hydrocarbon substance, detectable on exposed surfaces, that did not adversely contaminate the solvent within the limits of the testing. We recommend contacting the vendor to determine the source and purpose of this component, or, alternatively, pursue the infrared analysis of the PEEK in an effort to better define potential impacts.

  1. Green Solvents for Precision Cleaning

    NASA Technical Reports Server (NTRS)

    Grandelli, Heather; Maloney, Phillip; DeVor, Robert; Surma, Jan; Hintze, Paul

    2013-01-01

    Aerospace machinery used in liquid oxygen (LOX) fuel systems must be precision cleaned to achieve a very low level of non-volatile residue (< 1 mg0.1 m2), especially flammable residue. Traditionally chlorofluorocarbons (CFCs) have been used in the precision cleaning of LOX systems, specifically CFC 113 (C2Cl3F3). CFCs have been known to cause the depletion of ozone and in 1987, were banned by the Montreal Protocol due to health, safety and environmental concerns. This has now led to the development of new processes in the precision cleaning of aerospace components. An ideal solvent-replacement is non-flammable, environmentally benign, non-corrosive, inexpensive, effective and evaporates completely, leaving no residue. Highlighted is a green precision cleaning process, which is contaminant removal using supercritical carbon dioxide as the environmentally benign solvent. In this process, the contaminant is dissolved in carbon dioxide, and the parts are recovered at the end of the cleaning process completely dry and ready for use. Typical contaminants of aerospace components include hydrocarbon greases, hydraulic fluids, silicone fluids and greases, fluorocarbon fluids and greases and fingerprint oil. Metallic aerospace components range from small nuts and bolts to much larger parts, such as butterfly valves 18 in diameter. A fluorinated grease, Krytox, is investigated as a model contaminant in these preliminary studies, and aluminum coupons are employed as a model aerospace component. Preliminary studies are presented in which the experimental parameters are optimized for removal of Krytox from aluminum coupons in a stirred-batch process. The experimental conditions investigated are temperature, pressure, exposure time and impeller speed. Temperatures of 308 - 423 K, pressures in the range of 8.3 - 41.4 MPa, exposure times between 5 - 60 min and impeller speeds of 0 - 1000 rpm were investigated. Preliminary results showed up to 86 cleaning efficiency with the

  2. Pixelation Effects in Weak Lensing

    NASA Astrophysics Data System (ADS)

    High, F. William; Rhodes, Jason; Massey, Richard; Ellis, Richard

    2007-11-01

    Weak gravitational lensing can be used to investigate both dark matter and dark energy but requires accurate measurements of the shapes of faint, distant galaxies. Such measurements are hindered by the finite resolution and pixel scale of digital cameras. We investigate the optimum choice of pixel scale for a space-based mission, using the engineering model and survey strategy of the proposed Supernova Acceleration Probe as a baseline. We do this by simulating realistic astronomical images containing a known input shear signal and then attempting to recover the signal using the Rhodes, Refregier, & Groth algorithm. We find that the quality of shear measurement is always improved by smaller pixels. However, in practice, telescopes are usually limited to a finite number of pixels and operational life span, so the total area of a survey increases with pixel size. We therefore fix the survey lifetime and the number of pixels in the focal plane while varying the pixel scale, thereby effectively varying the survey size. In a pure trade-off for image resolution versus survey area, we find that measurements of the matter power spectrum would have minimum statistical error with a pixel scale of 0.09" for a 0.14" FWHM point-spread function (PSF). The pixel scale could be increased to ~0.16" if images dithered by exactly half-pixel offsets were always available. Some of our results do depend on our adopted shape measurement method and should be regarded as an upper limit: future pipelines may require smaller pixels to overcome systematic floors not yet accessible, and, in certain circumstances, measuring the shape of the PSF might be more difficult than those of galaxies. However, the relative trends in our analysis are robust, especially those of the surface density of resolved galaxies. Our approach thus provides a snapshot of potential in available technology, and a practical counterpart to analytic studies of pixelation, which necessarily assume an idealized shape

  3. Weak {}^* convergence of operator means

    NASA Astrophysics Data System (ADS)

    Romanov, Alexandr V.

    2011-12-01

    For a linear operator U with \\Vert U^n\\Vert \\le \\operatorname{const} on a Banach space X we discuss conditions for the convergence of ergodic operator nets T_\\alpha corresponding to the adjoint operator U^* of U in the {W^*O}-topology of the space \\operatorname{End} X^*. The accumulation points of all possible nets of this kind form a compact convex set L in \\operatorname{End} X^*, which is the kernel of the operator semigroup G=\\overline{\\operatorname{co}}\\,\\Gamma_0, where \\Gamma_0=\\{U_n^*, n \\ge 0\\}. It is proved that all ergodic nets T_\\alpha weakly {}^* converge if and only if the kernel L consists of a single element. In the case of X=C(\\Omega) and the shift operator U generated by a continuous transformation \\varphi of a metrizable compactum \\Omega we trace the relationships among the ergodic properties of U, the structure of the operator semigroups L, G and \\Gamma=\\overline{\\Gamma}_0, and the dynamical characteristics of the semi-cascade (\\varphi,\\Omega). In particular, if \\operatorname{card}L=1, then a) for any \\omega \\in\\Omega the closure of the trajectory \\{\\varphi^n\\omega, n \\ge 0\\} contains precisely one minimal set m, and b) the restriction (\\varphi,m) is strictly ergodic. Condition a) implies the {W^*O}-convergence of any ergodic sequence of operators T_n \\in \\operatorname{End} X^* under the additional assumption that the kernel of the enveloping semigroup E(\\varphi,\\Omega) contains elements obtained from the `basis' family of transformations \\{\\varphi^n, n \\ge 0\\} of the compact set \\Omega by using some transfinite sequence of sequential passages to the limit.

  4. Solvent dependent ordering of poly(3-dodecylthiophene) in thin films.

    PubMed

    Roy, I; Hazra, S

    2015-05-14

    The strong influence of solvents on the ordering of poly(3-dodecylthiophene) (P3DDT) due to edge-on oriented stacking, in the spin-coated thin film on the Si substrate, both near the substrate and away from it, depending upon the substrate surface nature, is observed from the X-ray reflectivity study. The absence of any appreciable amount of coil-like P3DDT chains (i.e. charge localized states) and formation of π-stacked aggregates (i.e. charge delocalized states) in the spin-coated thin films, with slightly better uniformity for the film prepared from toluene (TL) compared to that prepared from chloroform (CF) and chlorobenzene (CB), are well evident from the optical absorption study. No ordering near the weakly hydrophobic H-Si substrate is found in the films prepared from TL, probably due to less diffusion of P3DDT in TL and the appreciable pinning (film-substrate interaction) effect, while appreciable ordering near the film-air interface, overcoming the pinning effect, is likely to be related to the moderate values of the viscosity and the evaporation rate of the solvent. A better ordered Form-I-like relaxed structure near the film-substrate interface and a less ordered interpenetrating Form-II-like structure toward the film-air interface are found in the films prepared from CF, probably related to the low viscosity and high evaporation rate, respectively, of the solvent. Less ordered and mixed but more toward Form-II-like structures are formed throughout the film prepared from CB, probably due to the high viscosity of the solvent, even though its evaporation rate is low. The high evaporation rate of CF and high viscosity of CB probably create hindrance in the formation of continuous films on the weakly hydrophilic O-Si substrate at low speed, while the moderate values of both the parameters for TL, help to form continuous films on the O-Si substrate even at low speed. Such moderate values also help to form less variable (and more toward Form

  5. Single polymer chains in poor solvent: Using the bond fluctuation method with explicit solvent

    NASA Astrophysics Data System (ADS)

    Jentzsch, Christoph; Werner, Marco; Sommer, Jens-Uwe

    2013-03-01

    We use the bond fluctuation model with explicit solvent to study single polymer chains under poor solvent conditions. Static and dynamic properties of the bond fluctuation model with explicit solvent are compared with the implicit solvent model, and the Θ-temperatures are determined for both solvent models. We show that even in the very poor solvent regime, dynamics is not frozen for the explicit solvent model. We investigate some aspects of the structure of a single collapsed globule and show that rather large chain lengths are necessary to reach the scaling regime of a dense sphere. The force-extension curve of a single polymer chain under poor solvent conditions in the fixed end-to-end distance ensemble is analyzed. We find that the transition of the tadpole conformation to the stretched chain conformation is rather smooth because of fluctuation effects, which is in agreement with recent experimental results.

  6. Wide electrochemical window solvents for use in electrochemical devices and electrolyte solutions incorporating such solvents

    DOEpatents

    Angell, Charles Austen; Zhang, Sheng-Shui; Xu, Kang

    1998-01-01

    The present invention relates to electrolyte solvents for use in liquid or rubbery electrolyte solutions. Specifically, this invention is directed to boron-containing electrolyte solvents and boron-containing electrolyte solutions.

  7. Principles of Coordination Polymerisation

    NASA Astrophysics Data System (ADS)

    Kuran, Witold

    2001-11-01

    The first all-inclusive text covering coordination polymerisation, including important classes of non-hydrocarbon monomers. Charting the achievements and progress in the field, in terms of both basic and industrial research, this book offers a unified and complete overview of coordination polymerisation. Provides detailed description of the historical development of the subject Presents a unified view of catalysis, mechanisms, structures and utility Encourages learning through a step-by-step progression from basic to in-depth text Features end-of-chapter exercises to reinforce understanding Offers a full bibliography and comprehensive literature review Requisite reading for research students studying introductory and advanced courses in; polymer science, catalysis and polymerisation catalysis, and valuable reference for researchers and technicians in industry.

  8. Shared Activity Coordination

    NASA Technical Reports Server (NTRS)

    Clement, Bradley J.; Barrett, Anthony C.

    2003-01-01

    Interacting agents that interleave planning and execution must reach consensus on their commitments to each other. In domains where agents have varying degrees of interaction and different constraints on communication and computation, agents will require different coordination protocols in order to efficiently reach consensus in real time. We briefly describe a largely unexplored class of real-time, distributed planning problems (inspired by interacting spacecraft missions), new challenges they pose, and a general approach to solving the problems. These problems involve self-interested agents that have infrequent communication but collaborate on joint activities. We describe a Shared Activity Coordination (SHAC) framework that provides a decentralized algorithm for negotiating the scheduling of shared activities in a dynamic environment, a soft, real-time approach to reaching consensus during execution with limited communication, and a foundation for customizing protocols for negotiating planner interactions. We apply SHAC to a realistic simulation of interacting Mars missions and illustrate the simplicity of protocol development.

  9. EXAFS study into the speciation of metal salts dissolved in ionic liquids and deep eutectic solvents.

    PubMed

    Hartley, Jennifer M; Ip, Chung-Man; Forrest, Gregory C H; Singh, Kuldip; Gurman, Stephen J; Ryder, Karl S; Abbott, Andrew P; Frisch, Gero

    2014-06-16

    The speciation of metals in solution controls their reactivity, and this is extremely pertinent in the area of metal salts dissolved in ionic liquids. In the current study, the speciation of 25 metal salts is investigated in four deep eutectic solvents (DESs) and five imidazolium-based ionic liquids using extended X-ray absorption fine structure. It is shown that in diol-based DESs M(I) ions form [MCl2](-) and [MCl3](2-) complexes, while all M(II) ions form [MCl4](2-) complexes, with the exception of Ni(II), which exhibits a very unusual coordination by glycol molecules. This was also found in the X-ray crystal structure of the compound [Ni(phen)2(eg)]Cl2·2eg (eg = ethylene glycol). In a urea-based DES, either pure chloro or chloro-oxo coordination is observed. In [C6mim][Cl] pure chloro complexation is also observed, but coordination numbers are smaller (typically 3), which can be explained by the long alkyl chain of the cation. In [C2mim][SCN] metal ions are entirely coordinated by thiocyanate, either through the N or the S atom, depending on the hardness of the metal ion according to the hard-soft acid-base principle. With weaker coordinating anions, mixed coordination between solvent and solute anions is observed. The effect of hydrate or added water on speciation is insignificant for the diol-based DESs and small in other liquids with intermediate or strong ligands. One of the main findings of this study is that, with respect to metal speciation, there is no fundamental difference between deep eutectic solvents and classic ionic liquids. PMID:24897923

  10. Standard test method for nonvolatile residue of volatile cleaning solvents using the solvent purity meter

    SciTech Connect

    Not Available

    1980-01-01

    This method covers the determination of nonvolatile residue of volatile cleaning solvents using a solvent purity meter. The residue is concentrated in aerosol form by evaporation of the more volatile solvents. The volume of the concentrated aerosol is passed by a forward light scattering photometer. Experimentally devised curves relating photometer output to nonvolatile residue concentration are used to obtain parts per million of nonvolatile residue content of the cleaning solvents.

  11. The role of the solvent in PMMA gel polymer electrolytes

    NASA Astrophysics Data System (ADS)

    Vondrák, J.; Musil, M.; Sedlaříková, M.; Kořínek, R.; Bartušek, K.; Fedorková, A.

    2016-03-01

    Ionic mobility and solvent vapor pressure were studied on gels containing sodium perchlorate, polymethylmethacrylate and sulfolane as a solvent. The excess of solvent increases markedly the mobility of ions and is indicated by solvent evaporation at elevated temperature. The solvent is bonded similarly as in the liquid solution of sodium salt. The heat of solvent evaporation from gels is near to that of pure solvents.

  12. Hipparchus' coordinate system

    NASA Astrophysics Data System (ADS)

    Duke, Dennis W.

    2002-07-01

    In his "Histoire de l'Astronomie Ancienne" Delambre concludes unequivocally that Hipparchus knew and used a definite system of celestial spherical coordinates, namely the right ascension and declination system that we use today. The basis of Delambre's conclusion was disarmingly simple: he pointed out that in the "Commentary to Aratus" Hipparchus actually quotes the positions of numerous stars directly in right ascension and declination (or more often its complement, polar distance). Nearly two centuries later, in his "A History of Ancient Mathematical Astronomy", Neugebauer not only completely ignores Delambre's conclusion on this issue, but goes further to propose his own, as we shall see quite fanciful, theory that begins "From the Commentary to Aratus, it is quite obvious that at Hipparchus' time a definite system of spherical coordinates for stellar positions did not yet exist." and concludes "...nowhere in Greek astronomy before the catalogue of stars in the Almagest is it attested that orthogonal spherical coordinates are used to determine stellar positions." Today it is clear that Neugebauer's theory is conventionally accepted. It is the purpose of this paper to offer fresh arguments that Delambre was correct.

  13. Coordinating Shared Activities

    NASA Technical Reports Server (NTRS)

    Clement, Bradley

    2004-01-01

    Shared Activity Coordination (ShAC) is a computer program for planning and scheduling the activities of an autonomous team of interacting spacecraft and exploratory robots. ShAC could also be adapted to such terrestrial uses as helping multiple factory managers work toward competing goals while sharing such common resources as floor space, raw materials, and transports. ShAC iteratively invokes the Continuous Activity Scheduling Planning Execution and Replanning (CASPER) program to replan and propagate changes to other planning programs in an effort to resolve conflicts. A domain-expert specifies which activities and parameters thereof are shared and reports the expected conditions and effects of these activities on the environment. By specifying these conditions and effects differently for each planning program, the domain-expert subprogram defines roles that each spacecraft plays in a coordinated activity. The domain-expert subprogram also specifies which planning program has scheduling control over each shared activity. ShAC enables sharing of information, consensus over the scheduling of collaborative activities, and distributed conflict resolution. As the other planning programs incorporate new goals and alter their schedules in the changing environment, ShAC continually coordinates to respond to unexpected events.

  14. Instrumental systematics and weak gravitational lensing

    NASA Astrophysics Data System (ADS)

    Mandelbaum, R.

    2015-05-01

    We present a pedagogical review of the weak gravitational lensing measurement process and its connection to major scientific questions such as dark matter and dark energy. Then we describe common ways of parametrizing systematic errors and understanding how they affect weak lensing measurements. Finally, we discuss several instrumental systematics and how they fit into this context, and conclude with some future perspective on how progress can be made in understanding the impact of instrumental systematics on weak lensing measurements.

  15. Spin effects in the weak interaction

    SciTech Connect

    Freedman, S.J. Chicago Univ., IL . Dept. of Physics Chicago Univ., IL . Enrico Fermi Inst.)

    1990-01-01

    Modern experiments investigating the beta decay of the neutron and light nuclei are still providing important constraints on the theory of the weak interaction. Beta decay experiments are yielding more precise values for allowed and induced weak coupling constants and putting constraints on possible extensions to the standard electroweak model. Here we emphasize the implications of recent experiments to pin down the strengths of the weak vector and axial vector couplings of the nucleon.

  16. Tri-peptide reference structures for the calculation of relative solvent accessible surface area in protein amino acid residues.

    PubMed

    Topham, Christopher M; Smith, Jeremy C

    2015-02-01

    Relative amino acid residue solvent accessibility values allow the quantitative comparison of atomic solvent-accessible surface areas in different residue types and physical environments in proteins and in protein structural alignments. Geometry-optimised tri-peptide structures in extended solvent-exposed reference conformations have been obtained for 43 amino acid residue types at a high level of quantum chemical theory. Significant increases in side-chain solvent accessibility, offset by reductions in main-chain atom solvent exposure, were observed for standard residue types in partially geometry-optimised structures when compared to non-minimised models built from identical sets of proper dihedral angles abstracted from the literature. Optimisation of proper dihedral angles led most notably to marked increases of up to 54% in proline main-chain atom solvent accessibility compared to literature values. Similar effects were observed for fully-optimised tri-peptides in implicit solvent. The relief of internal strain energy was associated with systematic variation in N, C(α) and C(β) atom solvent accessibility across all standard residue types. The results underline the importance of optimisation of 'hard' degrees of freedom (bond lengths and valence bond angles) and improper dihedral angle values from force field or other context-independent reference values, and impact on the use of standardised fixed internal co-ordinate geometry in sampling approaches to the determination of absolute values of protein amino acid residue solvent accessibility. Quantum chemical methods provide a useful and accurate alternative to molecular mechanics methods to perform energy minimisation of peptides containing non-standard (chemically modified) amino acid residues frequently present in experimental protein structure data sets, for which force field parameters may not be available. Reference tri-peptide atomic co-ordinate sets including hydrogen atoms are made freely available

  17. EXPERIENCES IN DESIGNING SOLVENTS FOR THE ENVIRONMENT

    EPA Science Inventory

    Solvents used throughout industry are chosen to meet specific technological requirements such as solute solubility, cleaning and degreasing, or being a medium for paints and coatings. With the increasing awareness of the human health effects and environmental tisks of solvent use...

  18. EXPERIENCES IN DESIGNING SOLVENTS FOR THE ENVIRONMENT

    EPA Science Inventory

    Solvents used throughout industry are chosen to meet specific technological requirements such as solute solubility, cleaning and degreasing, or being a medium for paints and coatings. With the increasing awareness of the human health effects and environmental risks of solvent use...

  19. Improved Supercritical-Solvent Extraction of Coal

    NASA Technical Reports Server (NTRS)

    Compton, L.

    1982-01-01

    Raw coal upgraded by supercritical-solvent extraction system that uses two materials instead of one. System achieved extraction yields of 20 to 49 weight percent. Single-solvent yields are about 25 weight percent. Experimental results show extraction yields may be timedependent. Observed decreases in weight of coal agreed well with increases in ash content of residue.

  20. Supercritical-Multiple-Solvent Extraction From Coal

    NASA Technical Reports Server (NTRS)

    Corcoran, W.; Fong, W.; Pichaichanarong, P.; Chan, P.; Lawson, D.

    1983-01-01

    Large and small molecules dissolve different constituents. Experimental apparatus used to test supercritical extraction of hydrogen rich compounds from coal in various organic solvents. In decreasing order of importance, relevant process parameters were found to be temperature, solvent type, pressure, and residence time.

  1. SOLVENT-FREE ORGANIC SYNTHESES USING MICROWAVES

    EPA Science Inventory

    The latest results on microwave-expedited solvent-free approach as applied to the assembly of organic molecules will be presented. The salient features of this expeditious methodology such as solvent conservation and ease of manipulation etc. will be described in the context of r...

  2. SOLVENT DESIGN UNDER VARYING ENVIRONMENTAL REQUIREMENTS

    EPA Science Inventory

    There is currently a great need to replace many solvents that are commonly used by industry and the public, but whose continued use entails a number of human health and environmental risks. One issue hampering solvent replacement is the general thought that replacement, particul...

  3. Remediating pesticide contaminated soils using solvent extraction

    SciTech Connect

    Sahle-Demessie, E.; Meckes, M.C.; Richardson, T.L.

    1996-12-31

    Bench-scale solvent extraction studies were performed on soil samples obtained from a Superfund site contaminated with high levels of p,p{prime}-DDT, p,p{prime}-DDE and toxaphene. The effectiveness of the solvent extraction process was assessed using methanol and 2-propanol as solvents over a wide range of operating conditions. It was demonstrated that a six-stage methanol extraction using a solvent-to-soil ratio of 1.6 can decrease pesticide levels in the soil by more than 99% and reduce the volume of material requiring further treatment by 25 times or more. The high solubility of the pesticides in methanol resulted in rapid extraction rates, with the system reaching quasi-equilibrium state in 30 minutes. The extraction efficiency was influenced by the number of extraction stages, the solvent-to-soil ratio, and the soil moisture content. Various methods were investigated to regenerate and recycle the solvent. Evaporation and solvent stripping are low cost and reliable methods for removing high pesticide concentrations from the solvent. For low concentrations, GAC adsorption may be used. Precipitating and filtering pesticides by adding water to the methanol/pesticide solution was not successful when tested with soil extracts. 26 refs., 10 figs., 6 tabs.

  4. Classification of Solvents according to Interaction Mechanisms.

    ERIC Educational Resources Information Center

    Ahmed, Wasi

    1979-01-01

    Presented is a model for solvent effects based on the observation that the excitation energy of all-trans-N-Retinylidenmethyl-n-butylammonium iodide is directly related to the dielectric constant of a series of aromatic and aliphatic solvents as the dielectric constant (e) ranges from 2 to 10.5. (BT)

  5. REMEDIATING PESTICIDE CONTAMINATED SOILS USING SOLVENT EXTRACTION

    EPA Science Inventory

    Bench-scale solvent extraction studies were performed on soil samples obtained from a Superfund site contaminated with high levels of p,p'-DDT, p,p'-DDD,, p,p'-DDE and toxaphene. The effectiveness of the solvent extraction process was assessed using methanol and 2-propanol as sol...

  6. Green chemicals: Searching for cleaner solvents

    SciTech Connect

    Lucas, A.

    1994-10-05

    While increased pressure from EPA has solvents producers scrambling to find greener alternatives, many say the cost effectiveness and performance characteristics of traditional technologies are such that they will not disappear quickly. Though a variety of alternative {open_quotes}green{close_quotes} solvents have been developed and commercialized, better means of solvent recovery have also come along, ensuring continued use of many organic solvents. The 1990 Clean Air Act (CAA), designed to eliminate volatile organic compounds (VOCs), ozone depleters, and other hazardous air pollutants (HAPs), has put limits on many organic solvents. Those most under fire are chlorinated solvents, such as methylene chloride, 1,1,1 trichloroethylene (methyl chloroform), and chlorofluorocarbon (CFC)-113. Producers have been developing a variety of lower VOC solvents to replace those being phased out or regulated. Among those likely to experience most growth are aliphatic hydrocarbons to replace chlorinated solvents in cleaning applications. Growth is also expected for alcohols, esters, and glycol ethers for other end-use applications.

  7. REMEDIATION OF CONTAMINATED SOILS BY SOLVENT FLUSHING

    EPA Science Inventory

    Solvent flushing is a potential technique for remediating a waste disposal/spill site contaminated with organic chemicals. This technique involves the injection of a solvent mixture (e.g., water plus alcohols) that enhances contaminant solubility, reduces the retardation factor, ...

  8. Pneumatic conveying of pulverized solvent refined coal

    DOEpatents

    Lennon, Dennis R.

    1984-11-06

    A method for pneumatically conveying solvent refined coal to a burner under conditions of dilute phase pneumatic flow so as to prevent saltation of the solvent refined coal in the transport line by maintaining the transport fluid velocity above approximately 95 ft/sec.

  9. Gallium complexes and solvent extraction of gallium

    SciTech Connect

    Coleman, J.P.; Graham, C.R.; Monzyk, B.F.

    1988-05-03

    This patent describes a process for recovering gallium from aqueous solutions containing gallium which comprises contacting such a solution with an organic solvent containing at least 2% by weight of a water-insoluble N-organo hydroxamic acid having at least about 8 carbon atoms to extract gallium, and separating the gallium loaded organic solvent phase from the aqueous phase.

  10. Hydrogen Bond Lifetimes and Energetics for Solute-Solvent Complexes Studied with 2D-IR Vibrational Echo Spectroscopy

    PubMed Central

    Zheng, Junrong; Fayer, Michael D.

    2008-01-01

    Weak π hydrogen bonded solute-solvent complexes are studied with ultrafast two dimensional infrared (2D-IR) vibrational echo chemical exchange spectroscopy, temperature dependent IR absorption spectroscopy, and density functional theory calculations. Eight solute-solvent complexes composed of a number of phenol derivatives and various benzene derivatives are investigated. The complexes are formed between the phenol derivative (solute) in a mixed solvent of the benzene derivative and CCl4. The time dependence of the 2D-IR vibrational echo spectra of the phenol hydroxyl stretch is used to directly determine the dissociation and formation rates of the hydrogen bonded complexes. The dissociation rates of the weak hydrogen bonds are found to be strongly correlated with their formation enthalpies. The correlation can be described with an equation similar to the Arrhenius equation. The results are discussed in terms of transition state theory. PMID:17373792

  11. Organic solvent regeneration of granular activated carbon

    NASA Astrophysics Data System (ADS)

    Cross, W. H.; Suidan, M. T.; Roller, M. A.; Kim, B. R.; Gould, J. P.

    1982-09-01

    The use of activated carbon for the treatment of industrial waste-streams was shown to be an effective treatment. The high costs associated with the replacement or thermal regeneration of the carbon have prohibited the economic feasibility of this process. The in situ solvent regeneration of activated carbon by means of organic solvent extraction was suggested as an economically alternative to thermal regeneration. The important aspects of the solvent regeneration process include: the physical and chemical characteristics of the adsorbent, the pore size distribution and energy of adsorption associated with the activated carbon; the degree of solubility of the adsorbate in the organic solvent; the miscibility of the organic solvent in water; and the temperature at which the generation is performed.

  12. Toxic hepatitis in occupational exposure to solvents

    PubMed Central

    Malaguarnera, Giulia; Cataudella, Emanuela; Giordano, Maria; Nunnari, Giuseppe; Chisari, Giuseppe; Malaguarnera, Mariano

    2012-01-01

    The liver is the main organ responsible for the metabolism of drugs and toxic chemicals, and so is the primary target organ for many organic solvents. Work activities with hepatotoxins exposures are numerous and, moreover, organic solvents are used in various industrial processes. Organic solvents used in different industrial processes may be associated with hepatotoxicity. Several factors contribute to liver toxicity; among these are: species differences, nutritional condition, genetic factors, interaction with medications in use, alcohol abuse and interaction, and age. This review addresses the mechanisms of hepatotoxicity. The main pathogenic mechanisms responsible for functional and organic damage caused by solvents are: inflammation, dysfunction of cytochrome P450, mitochondrial dysfunction and oxidative stress. The health impact of exposure to solvents in the workplace remains an interesting and worrying question for professional health work. PMID:22719183

  13. SOLVENT DISPERSION AND FLOW METER CALCULATION RESULTS

    SciTech Connect

    Nash, C.; Fondeur, F.; Peters, T.

    2013-06-21

    Savannah River National Laboratory (SRNL) found that the dispersion numbers for the six combinations of CSSX:Next Generation Solvent (NGS) “blend” and pure NGS versus salt solution, caustic wash, and strip aqueous solutions are all good. The dispersion numbers are indications of processability with centrifugal contactors. A comparison of solvent physical and thermal properties shows that the Intek™ solvent flow meter in the plant has a reading biased high versus calibrated flow when NGS is used, versus the standard CSSX solvent. The flow meter, calibrated for CSSX solvent, is predicted to read 2.8 gpm of NGS in a case where the true flow of NGS is 2.16 gpm.

  14. Hydrocarbon-solvent based cleaners as replacements for chlorinated and CFC solvents

    SciTech Connect

    Schreiner, J.L.; Berlin, E.P.

    1995-12-31

    Chlorinated and CFC solvents have been used for about 30 years to remove various contaminants from products during the manufacturing process. Among the contaminants being removed are oils, greases, and waxes that have petroleum products as the base. Prior to the advent of the chlorinated solvents petroleum distillates were used for these cleaning operations. Processing improvements over the past 30 years now permit production of higher purity hydrocarbons solvents that can be used as replacements for the chlorinated and CFC solvents being phased out. These hydrocarbon solvents are well suited for removal of the various petroleum based contaminants, as one recalls the old adage {open_quotes}like dissolves like.{close_quotes}

  15. Multipole Structure and Coordinate Systems

    ERIC Educational Resources Information Center

    Burko, Lior M.

    2007-01-01

    Multipole expansions depend on the coordinate system, so that coefficients of multipole moments can be set equal to zero by an appropriate choice of coordinates. Therefore, it is meaningless to say that a physical system has a nonvanishing quadrupole moment, say, without specifying which coordinate system is used. (Except if this moment is the…

  16. Alternative control technology document: Halogenated solvent cleaners. Final report

    SciTech Connect

    Not Available

    1989-08-01

    The document contains information on the use and control of halogenated solvents in solvent-cleaning applications. Described are the types of solvent cleaners manufactured, sources of solvent emissions, methods of controlling solvent emissions, and the costs associated with installation of control devices.

  17. PARIS II: Computer Aided Solvent Design for Pollution Prevention

    EPA Science Inventory

    This product is a summary of U.S. EPA researchers' work developing the solvent substitution software tool PARIS II (Program for Assisting the Replacement of Industrial Solvents, version 2.0). PARIS II finds less toxic solvents or solvent mixtures to replace more toxic solvents co...

  18. Predicting the Solubility of Pharmaceutical Cocrystals in Solvent/Anti-Solvent Mixtures.

    PubMed

    Lange, Linda; Heisel, Stefan; Sadowski, Gabriele

    2016-01-01

    In this work, the solubilities of pharmaceutical cocrystals in solvent/anti-solvent systems were predicted using PC-SAFT in order to increase the efficiency of cocrystal formation processes. Modeling results and experimental data were compared for the cocrystal system nicotinamide/succinic acid (2:1) in the solvent/anti-solvent mixtures ethanol/water, ethanol/acetonitrile and ethanol/ethyl acetate at 298.15 K and in the ethanol/ethyl acetate mixture also at 310.15 K. The solubility of the investigated cocrystal slightly increased when adding small amounts of anti-solvent to the solvent, but drastically decreased for high anti-solvent amounts. Furthermore, the solubilities of nicotinamide, succinic acid and the cocrystal in the considered solvent/anti-solvent mixtures showed strong deviations from ideal-solution behavior. However, by accounting for the thermodynamic non-ideality of the components, PC-SAFT is able to predict the solubilities in all above-mentioned solvent/anti-solvent systems in good agreement with the experimental data. PMID:27164075

  19. Work Coordination Engine

    NASA Technical Reports Server (NTRS)

    Zendejas, Silvino; Bui, Tung; Bui, Bach; Malhotra, Shantanu; Chen, Fannie; Kim, Rachel; Allen, Christopher; Luong, Ivy; Chang, George; Sadaqathulla, Syed

    2009-01-01

    The Work Coordination Engine (WCE) is a Java application integrated into the Service Management Database (SMDB), which coordinates the dispatching and monitoring of a work order system. WCE de-queues work orders from SMDB and orchestrates the dispatching of work to a registered set of software worker applications distributed over a set of local, or remote, heterogeneous computing systems. WCE monitors the execution of work orders once dispatched, and accepts the results of the work order by storing to the SMDB persistent store. The software leverages the use of a relational database, Java Messaging System (JMS), and Web Services using Simple Object Access Protocol (SOAP) technologies to implement an efficient work-order dispatching mechanism capable of coordinating the work of multiple computer servers on various platforms working concurrently on different, or similar, types of data or algorithmic processing. Existing (legacy) applications can be wrapped with a proxy object so that no changes to the application are needed to make them available for integration into the work order system as "workers." WCE automatically reschedules work orders that fail to be executed by one server to a different server if available. From initiation to completion, the system manages the execution state of work orders and workers via a well-defined set of events, states, and actions. It allows for configurable work-order execution timeouts by work-order type. This innovation eliminates a current processing bottleneck by providing a highly scalable, distributed work-order system used to quickly generate products needed by the Deep Space Network (DSN) to support space flight operations. WCE is driven by asynchronous messages delivered via JMS indicating the availability of new work or workers. It runs completely unattended in support of the lights-out operations concept in the DSN.

  20. AN ACCELERATED RATE CALORIMETRY STUDY OF CAUSTIC-SIDE SOLVENT EXTRACTION SOLVENT WITHOUT EXTRACTANT

    SciTech Connect

    Fondeur, F; Samuel Fink, S

    2006-03-07

    This study found that 4 - 48 part per thousand (ppth) of Caustic Side Solvent Extraction (CSSX) solvent without extractant in caustic salt solution at evaporator-relevant temperatures result in no process-significant energetic events. However, the data suggest a chemical reaction (possible decomposition) in the CSSX solvent near 140 C. This concentration of entrained solvent is believed to markedly exceed the amount of solvent that will pass from the Modular Caustic Side Solvent Unit (MCU) through the downstream Defense Waste Processing Facility and enter the evaporator through routine tank farm operations. The rate of pressure rise at 140 C differs appreciably - i.e., is reduced - for salt solution containing the organic from that of the same solution without solvent. This behavior is due to a reaction between the CSSX components and the salt solution simulant.

  1. Test reactor irradiation coordination

    SciTech Connect

    Heartherly, D.W.; Siman Tov, I.I.; Sparks, D.W.

    1995-10-01

    This task was established to supply and coordinate irradiation services needed by NRC contractors other than ORNL. These services include the design and assembly of irradiation capsules as well as arranging for their exposure, disassembly, and return of specimens. During this period, the final design of the facility and specimen baskets was determined through an iterative process involving the designers and thermal analysts. The resulting design should permit the irradiation of all test specimens to within 5{degrees}C of their desired temperature. Detailing of all parts is ongoing and should be completed during the next reporting period. Procurement of the facility will also be initiated during the next review period.

  2. Rapid and enhanced activation of microporous coordination polymers by flowing supercritical CO.sub.2

    DOEpatents

    Matzger, Adam J.; Liu, Baojian; Wong-Foy, Antek G.

    2016-07-19

    Flowing supercritical CO.sub.2 is used to activate metal organic framework materials (MOF). MOFs are activated directly from N,N-dimethylformamide (DMF) thus avoiding exchange with a volatile solvent. Most MCPs display increased surface areas directly after treatment although those with coordinatively unsaturated metal centers benefit from additional heating.

  3. Weak rigidity in the PPN formalism

    SciTech Connect

    del Olmo, V.; Olivert, J.

    1987-04-01

    The influence of the concept of weakly rigid almost-thermodynamic material schemes on the classical deformations is analyzed. The methods of the PPN approximation are considered. In this formalism, the equations that characterize the weak rigidity are expressed. As a consequence of that, an increase of two orders of magnitude in the strain rate tensor is obtained.

  4. On modeling weak sinks in MODPATH

    USGS Publications Warehouse

    Abrams, Daniel B.; Haitjema, Henk; Kauffman, Leon J.

    2012-01-01

    Regional groundwater flow systems often contain both strong sinks and weak sinks. A strong sink extracts water from the entire aquifer depth, while a weak sink lets some water pass underneath or over the actual sink. The numerical groundwater flow model MODFLOW may allow a sink cell to act as a strong or weak sink, hence extracting all water that enters the cell or allowing some of that water to pass. A physical strong sink can be modeled by either a strong sink cell or a weak sink cell, with the latter generally occurring in low resolution models. Likewise, a physical weak sink may also be represented by either type of sink cell. The representation of weak sinks in the particle tracing code MODPATH is more equivocal than in MODFLOW. With the appropriate parameterization of MODPATH, particle traces and their associated travel times to weak sink streams can be modeled with adequate accuracy, even in single layer models. Weak sink well cells, on the other hand, require special measures as proposed in the literature to generate correct particle traces and individual travel times and hence capture zones. We found that the transit time distributions for well water generally do not require special measures provided aquifer properties are locally homogeneous and the well draws water from the entire aquifer depth, an important observation for determining the response of a well to non-point contaminant inputs.

  5. Spin Seebeck effect in a weak ferromagnet

    NASA Astrophysics Data System (ADS)

    Arboleda, Juan David; Arnache Olmos, Oscar; Aguirre, Myriam Haydee; Ramos, Rafael; Anadon, Alberto; Ibarra, Manuel Ricardo

    2016-06-01

    We report the observation of room temperature spin Seebeck effect (SSE) in a weak ferromagnetic normal spinel Zinc Ferrite (ZFO). Despite the weak ferromagnetic behavior, the measurements of the SSE in ZFO show a thermoelectric voltage response comparable with the reported values for other ferromagnetic materials. Our results suggest that SSE might possibly originate from the surface magnetization of the ZFO.

  6. Staggering towards a calculation of weak amplitudes

    SciTech Connect

    Sharpe, S.R.

    1988-09-01

    An explanation is given of the methods required to calculate hadronic matrix elements of the weak Hamiltonians using lattice QCD with staggered fermions. New results are presented for the 1-loop perturbative mixing of the weak interaction operators. New numerical techniques designed for staggered fermions are described. A preliminary result for the kaon B parameter is presented. 24 refs., 3 figs.

  7. CP Violation, Neutral Currents, and Weak Equivalence

    DOE R&D Accomplishments Database

    Fitch, V. L.

    1972-03-23

    Within the past few months two excellent summaries of the state of our knowledge of the weak interactions have been presented. Correspondingly, we will not attempt a comprehensive review but instead concentrate this discussion on the status of CP violation, the question of the neutral currents, and the weak equivalence principle.

  8. Dendritic brushes under good solvent conditions: a simulation study.

    PubMed

    Gergidis, Leonidas N; Kalogirou, Andreas; Vlahos, Costas

    2012-12-11

    The structural properties of polymer brushes, formed by dendron polymers up to the third generation, were studied by means of Brownian dynamics simulations for the macroscopic state of good solvent. The distributions of polymer units, of the free ends, of the dendrons centers of mass, and of the units of every dendritic generation and the radii of gyration necessary for the understanding of the internal stratification of brushes were calculated. Previous self-consistent field theory numerical simulations of first-generation dendritic brushes suggested that at high grafting densities two kinds of populations are evident, one of short dendrons having weakly extended spacers and another with tall dendrons having strongly stretched spacers. These Brownian dynamics calculations provided a more complicated picture of dendritic brushes, revealing different populations of short, tall, and in some cases intermediate height dendrons, depending on the dendron generation and spacer length. The scaling dependence of the height and the span of the dendritic brush on the grafting density and other parameters were found to be in good agreement with existing theoretical results for good solvents. PMID:23134236

  9. Specific binding of ethanol to cholesterol in organic solvents.

    PubMed

    Daragan, V A; Voloshin, A M; Chochina, S V; Khazanovich, T N; Wood, W G; Avdulov, N A; Mayo, K H

    2000-07-01

    Although ethanol has been reported to affect cholesterol homeostasis in biological membranes, the molecular mechanism of action is unknown. Here, nuclear magnetic resonance (NMR) spectroscopic techniques have been used to investigate possible direct interactions between ethanol and cholesterol in various low dielectric solvents (acetone, methanol, isopropanol, DMF, DMSO, chloroform, and CCl(4)). Measurement of (13)C chemical shifts, spin-lattice and multiplet relaxation times, as well as self-diffusion coefficients, indicates that ethanol interacts weakly, yet specifically, with the HC-OH moiety and the two flanking methylenes in the cyclohexanol ring of cholesterol. This interaction is most strong in the least polar-solvent carbon tetrachloride where the ethanol-cholesterol equilibrium dissociation constant is estimated to be 2 x 10(-3) M. (13)C-NMR spin-lattice relaxation studies allow insight into the geometry of this complex, which is best modeled with the methyl group of ethanol sandwiched between the two methylenes in the cyclohexanol ring and the hydroxyl group of ethanol hydrogen bonded to the hydroxyl group of cholesterol.

  10. Advances in weak-values based metrology

    NASA Astrophysics Data System (ADS)

    Jordan, Andrew; Viza, Gerardo; Martínez-Rincón, Julián; Alves, Gabriel; Howell, John; Kwiat, Paul

    2015-03-01

    We theoretically and experimentally describe the relative advantages of implementing weak-values-based metrology versus standard methods. To accomplish this, we measure small optical beam deflections both a weak-values-based technique, and a standard technique. By introducing controlled external modulations of the detector, and transverse beam-jitter, we quantify the mitigation of these sources in the weak values-based experiment versus the standard experiment. In all cases, the weak-values technique performs the same or better than the standard technique by up to two orders of magnitude in precision for our parameters. We further measure the statistical efficiency of the weak-values-based technique. By post-selecting on 1% of the photons, we obtain 99% of the available Fisher information of the beam deflection parameter. We also discuss ways to recycle the discarded events, obtaining much greater precision on a measured parameter.

  11. Atomic homodyne detection of weak atomic transitions.

    PubMed

    Gunawardena, Mevan; Elliott, D S

    2007-01-26

    We have developed a two-color, two-pathway coherent control technique to detect and measure weak optical transitions in atoms by coherently beating the transition amplitude for the weak transition with that of a much stronger transition. We demonstrate the technique in atomic cesium, exciting the 6s(2)S(1/2) --> 8s(2)S(1/2) transition via a strong two-photon transition and a weak controllable Stark-induced transition. We discuss the enhancement in the signal-to-noise ratio for this measurement technique over that of direct detection of the weak transition rate, and project future refinements that may further improve its sensitivity and application to the measurement of other weak atomic interactions.

  12. Continual coordination of shared activities

    NASA Technical Reports Server (NTRS)

    Clement, B. J.; Barrett, A.

    2002-01-01

    Interacting agents that interleave planning and execution must reach consensus on their commitments to each other. For domains with varying degrees of interaction and different constraints on communication and computation, agents will require different coordination protocols in order to efficiently achieve their goals. ShAC (Shared Activity Coordination) is a framework for designing coordination protocols and an algorithm for continually coordinating agents using these protocols during execution. We show how a variety of protocols can be constructed using this framework and describe how ShAC coordinates two rovers and an orbiter in a simulated Mars scenario.

  13. Organic Solvent Tolerant Lipases and Applications

    PubMed Central

    Kanwar, Shamsher S.

    2014-01-01

    Lipases are a group of enzymes naturally endowed with the property of performing reactions in aqueous as well as organic solvents. The esterification reactions using lipase(s) could be performed in water-restricted organic media as organic solvent(s) not only improve(s) the solubility of substrate and reactant in reaction mixture but also permit(s) the reaction in the reverse direction, and often it is easy to recover the product in organic phase in two-phase equilibrium systems. The use of organic solvent tolerant lipase in organic media has exhibited many advantages: increased activity and stability, regiospecificity and stereoselectivity, higher solubility of substrate, ease of products recovery, and ability to shift the reaction equilibrium toward synthetic direction. Therefore the search for organic solvent tolerant enzymes has been an extensive area of research. A variety of fatty acid esters are now being produced commercially using immobilized lipase in nonaqueous solvents. This review describes the organic tolerance and industrial application of lipases. The main emphasis is to study the nature of organic solvent tolerant lipases. Also, the potential industrial applications that make lipases the biocatalysts of choice for the present and future have been presented. PMID:24672342

  14. Differential response of marine diatoms to solvents

    SciTech Connect

    Tadros, M.G.; Phillips, J.; Patel, H.; Pandiripally, V.

    1995-06-01

    Unicellular algae in aquatic ecosystems are subjected to a variety of pollutants from sources such as runoff from agricultural lands and industrial outfalls. Organic solvents are natural components of oil deposits and commonly find their way into surface waters as a result of discharges from refineries, waste oil, disposal, and accidental spills. Organic solvents can make their way into the environment as industrial wastes. Because of their carcinogenic potential, contamination of soil and water by solvents is cause for serious concern. Relatively few reports have been published on the comparative toxicity of solvents towards test organisms, and these dealt primarily with fish and aquatic invertebrates. However, only few data of toxicity effects of solvents on algae have been published. Phytoplankton species vary in their tolerance to trace metals. Diatoms in particular are able to detoxify trace metals by the excretion of organic compounds. A previous study reported that diatoms collected form different sites in the Gulf of Mexico varied in their physiological characteristics. Algae have been considered to be good indicator s of bioactivity of industrial wastes. Unicellular algae vary in their response to a variety of toxicants. Little is known, however, about toxicity of solvents to marine diatoms. The work reported here was done to examine the effect of selected solvents on seven diatom species to determine whether they differed in their responses to these chemicals. 16 refs., 1 fig.

  15. Environmental Impacts on Nuclear Reprocessing Solvents

    NASA Astrophysics Data System (ADS)

    Gillens, A. R.; Fessenden, J. E.

    2009-12-01

    Nuclear tests have been employed ever since the first nuclear explosion in Alamogordo, NM during the mid-1940s. Nuclear weapons pose a threat to civil society and result in extensive biological (medical) damages. For this reason, treaties banning nuclear tests and weapons have been employed since the 1960s to cease proliferation of weapons. However, as nuclear tests continue in secrecy and actinides, such as plutonium and uranium, are eligible for theft, nuclear forensics is needed to prevent weapons proliferation. In this study, solvents [tributyl phosphate (TBP), dodecane, decanol] used in reprocessing spent nuclear fuel are analyzed using an isotope ratio mass spectrometer, which provides indisputable evidence in identifying the operation in which solvents were used. Solvent samples are observed under variable conditions in the laboratory for different time periods. It is assumed that their carbon isotope values (δ13C) will become more positive (shift heavy) with time. It is found that the solvents are hygroscopic. TBP leaves the most robust signature compared to the other solvents studied and the isotope values for all solvents under all conditions become more positive with time. This study serves as primary research in understanding how solvents behave under variable conditions in the laboratory and how this could be translated to the environment in fate and transport studies.

  16. Conformal Fermi Coordinates

    SciTech Connect

    Dai, Liang; Pajer, Enrico; Schmidt, Fabian E-mail: Enrico.pajer@gmail.com

    2015-11-01

    Fermi Normal Coordinates (FNC) are a useful frame for isolating the locally observable, physical effects of a long-wavelength spacetime perturbation. Their cosmological application, however, is hampered by the fact that they are only valid on scales much smaller than the horizon. We introduce a generalization that we call Conformal Fermi Coordinates (CFC). CFC preserve all the advantages of FNC, but in addition are valid outside the horizon. They allow us to calculate the coupling of long- and short-wavelength modes on all scales larger than the sound horizon of the cosmological fluid, starting from the epoch of inflation until today, by removing the complications of the second order Einstein equations to a large extent, and eliminating all gauge ambiguities. As an application, we present a calculation of the effect of long-wavelength tensor modes on small scale density fluctuations. We recover previous results, but clarify the physical content of the individual contributions in terms of locally measurable effects and ''projection'' terms.

  17. Effect of solvent characteristics on coal liquefaction

    SciTech Connect

    Huang, He; Wang, Shaojie; Wang, Keyu; Klein, M.T.; Calkins, W.H.

    1996-12-31

    It has been known for a long time that the characteristics of the liquefaction solvent has a profound effect on direct coal liquefaction. The amount of hydrogen consumed during the liquefaction process, the degree and quantity of retrograde reactions that occur, and the quality of the liquid products are all influenced by the process solvent. A number of analytical approaches have been developed to determine the important characteristics of the solvent for coal liquefaction. The hydrogen donor ability has clearly been important. However, such other characteristics of a liquefaction solvent as solubility parameter, content and type of higher aromatic hydrocarbons, and phenolic content have also been found to be significant. Finseth et al. have shown that the bulk of the hydrogen consumed from an uncatalyzed donor solvent liquefaction above 400{degrees}C is consumed in gas generation, heteroatom removal and hydrogenolysis of the coal matrix. Wilson et al. have also shown that the major role of hydrogen in uncatalyzed liquefaction is consumed by alkyl fission and hydrogenolysis reactions and not with hydrogenating aromatic rings. McMillan et al. have postulated that a radical hydrogen transfer process along with donor solvent capping of thermally produced radicals from the coal as possible processes involved with the hydroaromatic donor solvents in coal liquefaction. With the development of a short contact time batch reactor (SCTBR), determining the influence of the processing solvent on the liquefaction rates, conversion profiles and the quality of the liquid product at a particular time became possible. The influence of type of solvent, combined with other effects, such as gas atmosphere (i.e., in hydrogen and in nitrogen) and catalyst, on the coal liquefaction is reported in this paper.

  18. THE DESIGN OF TECHNOLOGICALLY EFFECTIVE AND ENVIRONMENTALLY BENIGN SOLVENT SUBSTITUTES

    EPA Science Inventory

    There is presently considerable interest in finding environmentally benign replacement solvents that can perform in many different applications as solvents normally do. This requires solvents with desirable properties, e.g., ability to dissolve certain compounds, and without oth...

  19. Firing of pulverized solvent refined coal

    DOEpatents

    Lennon, Dennis R.; Snedden, Richard B.; Foster, Edward P.; Bellas, George T.

    1990-05-15

    A burner for the firing of pulverized solvent refined coal is constructed and operated such that the solvent refined coal can be fired successfully without any performance limitations and without the coking of the solvent refined coal on the burner components. The burner is provided with a tangential inlet of primary air and pulverized fuel, a vaned diffusion swirler for the mixture of primary air and fuel, a center water-cooled conical diffuser shielding the incoming fuel from the heat radiation from the flame and deflecting the primary air and fuel steam into the secondary air, and a watercooled annulus located between the primary air and secondary air flows.

  20. Molecular accessibility in solvent swelled coal

    SciTech Connect

    Kispert, L.D.

    1992-11-01

    To expand the information base on molecular accessibility in solvent swelled coal, Argonne Premium Coal Samples (APCS) were swelled in polar, basic solvents before and after moisture loss and upon air oxidation. So far studies have been reported on the changes in pore size distribution as a function of temperature when polar basic swelling solvents are used. Additional studies employing EPR spin probe techniques performed on the breaking up of the hydrogen bonding between bedding planes were later confirmed by magnetic resonance imaging at Argonne National Lab and the University of Illinois.

  1. Switchable solvents and methods of use thereof

    DOEpatents

    Jessop, Philip G.; Eckert, Charles A.; Liotta, Charles L.; Heldebrant, David J.

    2011-07-19

    A solvent that reversibly converts from a nonionic liquid mixture to an ionic liquid upon contact with a selected trigger, e.g., contact with CO.sub.2, is described. In preferred embodiments, the ionic solvent is readily converted back to the nonionic liquid mixture. The nonionic liquid mixture includes an amidine or guanidine or both, and water, alcohol, or a combination thereof. Single component amine solvents that reversibly convert between ionic and non-ionic states are also described. Some embodiments require increased pressure to convert; others convert at 1 atmosphere.

  2. Switchable solvents and methods of use thereof

    DOEpatents

    Jessop, Philip G.; Eckert, Charles A.; Liotta, Charles L.; Heldebrant, David J.

    2013-08-20

    A solvent that reversibly converts from a nonionic liquid mixture to an ionic liquid upon contact with a selected trigger, e.g., contact with CO.sub.2, is described. In preferred embodiments, the ionic solvent is readily converted back to the nonionic liquid mixture. The nonionic liquid mixture includes an amidine or guanidine or both, and water, alcohol, or a combination thereof. Single component amine solvents that reversibly convert between ionic and non-ionic states are also described. Some embodiments require increased pressure to convert; others convert at 1 atmosphere.

  3. Mechanism of paint removing by organic solvents

    SciTech Connect

    Del Nero, V.; Siat, C.; Marti, M.J.; Aubry, J.M.; Lallier, J.P.; Dupuy, N.; Huvenne, J.P.

    1996-01-01

    The mechanism of paint removing has been studied by comparing the stripping efficiency of a given solvent with its ability to swell the film. The most effective solvents have a Hildebrand{close_quote}s parameter, {delta}{sub H}, ranging from 10.5 to 12 and a Dimroth parameter, ET{sub (30)}, ranging from 0.25 to 0.4. The synergy observed with the mixtures DMSO/non polar solvent is explained by a dissociation of the DMSO clusters into individual molecules which diffuse more easily. {copyright} {ital 1996 American Institute of Physics.}

  4. What makes critical-solvent processes work

    SciTech Connect

    Brule, M.R.; Corbett, R.W.

    1984-06-01

    Critical-solvent processing (sometimes called supercritical-gas extraction) is an ongoing technology based on phase-equilibrium phenomena in the critical region. Many new practical applications of critical-solvent processing are being conceived and implemented in the food, drug and chemical industries. The advantages afforded by critical-solvent processing in performing difficult separations such as caffeine from coffee, nicotine from tobacco, chemotherapeutic drugs from plants, and chemical feedstocks from petroleum and synfuels residua have been realized just in the last decade or so.

  5. Reduction of solvent emissions from vapor degreasing

    SciTech Connect

    Buresh, P.

    1989-12-31

    Hutchinson Tehnology, Inc. (HTI) implemented a number of low cost, low technology procedures to reduce emissions and prevent solvent loss from two open-top freon (CFC-113) vapor degreasers (Branson No. 1 and No. 2). HTI is a computer components manufacturer that uses freon vapor degreasing systems to remove fluxes and other residues remaining on the flexible printed circuits from the soldering process. With relatively minor changes in operation, solvent emissions were reduced by an average of 2.8 gallons per day (GDP) for both degreasers combined. It is anticipated that HTI will follow through with installation of an automatic cover, which can result in further solvent emissions reduction.

  6. Optical nonlinearity of HBI in different solvents

    NASA Astrophysics Data System (ADS)

    Wu, Feng; Ma, Lina; Geng, Yaohui; Zhang, Siwen; Wang, Zhe; Cheng, Xiaoman

    2014-04-01

    2-(2'-Hydroxyphenyl) benzimidazole (HBI) is one kind of organic molecules featuring excited-state proton transfer (ESPT). The nonlinear optical properties of 2-(2'-hydroxyphenyl) benzimidazole (HBI) in different polar solvents were investigated by means of Z-scan technique under the excitation of the 1064 nm picoseconds laser pulse. The experimental results show that the nonlinear refractive indices decrease with the enhancement of the polarity of the solvent. The nonlinear refractive indices sensitive to the solvent polarity allow them to be widely used for the optoelectronic devices.

  7. Switchable solvents and methods of use thereof

    SciTech Connect

    Jessop, Philip G; Eckert, Charles A; Liotta, Charles L; Heldebrant, David J

    2014-04-29

    A solvent that reversibly converts from a nonionic liquid mixture to an ionic liquid upon contact with a selected trigger, e.g., contact with CO.sub.2, is described. In preferred embodiments, the ionic solvent is readily converted back to the nonionic liquid mixture. The nonionic liquid mixture includes an amidine or guanidine or both, and water, alcohol, or a combination thereof. Single component amine solvents that reversibly convert between ionic and non-ionic states are also described. Some embodiments require increased pressure to convert; others convert at 1 atmosphere.

  8. Cleaning solvent substitution in electronic assemblies

    SciTech Connect

    Meier, G.J.

    1993-09-01

    Alternatives to chlorinated and fluorinated solvents have been identified, qualified, and implemented into production of complex electronic assemblies. Extensive compatibility studies were performed with components, piece-parts, and materials. Electrical testing and accelerated aging were used to screen for detrimental, long-term effects. A terpene, d-limonene, has been selected as the solvent of choice for cleaning complex electronic assemblies, and has been found to be compatible with the components and materials tested. A brief history of the overall project will be presented, along with representative cleaning efficiency results, compatibility results, and residual solvent data.

  9. Genomic and Genetic Approaches to Solvent Tolerance

    SciTech Connect

    Eleftherios T. Papoutsakis

    2005-06-10

    The proposed research is to understand and exploit the molecular basis that determines tolerance of the industrially important anaerobic clostridia to solvents. Furthermore, we aim to develop general genomic and metabolic engineering strategies for understanding the molecular basis of tolerance to chemicals and for developing tolerant strains. Our hypothesis is that the molecular basis of what makes bacterial cells able to withstand high solvent concentrations can be used to metabolically engineer cells so that they can tolerate higher concentrations of solvents and related chemicals.

  10. Cyclic Solvent Vapor Annealing for Rapid, Robust Vertical Orientation of Features in BCP Thin Films

    NASA Astrophysics Data System (ADS)

    Paradiso, Sean; Delaney, Kris; Fredrickson, Glenn

    2015-03-01

    Methods for reliably controlling block copolymer self assembly have seen much attention over the past decade as new applications for nanostructured thin films emerge in the fields of nanopatterning and lithography. While solvent assisted annealing techniques are established as flexible and simple methods for achieving long range order, solvent annealing alone exhibits a very weak thermodynamic driving force for vertically orienting domains with respect to the free surface. To address the desire for oriented features, we have investigated a cyclic solvent vapor annealing (CSVA) approach that combines the mobility benefits of solvent annealing with selective stress experienced by structures oriented parallel to the free surface as the film is repeatedly swollen with solvent and dried. Using dynamical self-consistent field theory (DSCFT) calculations, we establish the conditions under which the method significantly outperforms both static and cyclic thermal annealing and implicate the orientation selection as a consequence of the swelling/deswelling process. Our results suggest that CSVA may prove to be a potent method for the rapid formation of highly ordered, vertically oriented features in block copolymer thin films.

  11. Origin of weak magnetism in compounds with cubic laves structure.

    PubMed

    Torun, E; Janner, A; de Groot, R A

    2016-02-17

    The origin of the weak itinerant magnetism in materials such as TiBe2 and ZrZn2 is investigated. The huge peak in the density of states at the Fermi energy is attributed to a special symmetry of the C15 structure: no crystal field splitting of the d levels occurs in the case of coordination by spherical ligands. Crystal field splitting is also investigated for the f orbitals in C15 structures such as PuZn2 and ThMg2. It is observed that the situation in f levels is more complicated than the d levels because the characteristics of the crystal field splitting for f levels does not only depend on the the local point symmetry of the compounds.

  12. Nonlinear response of a linear chain to weak driving

    NASA Astrophysics Data System (ADS)

    Hennig, D.; Mulhern, C.; Burbanks, A. D.; Schimansky-Geier, L.

    2014-01-01

    We study the escape of a chain of coupled units over the barrier of a metastable potential. It is demonstrated that a very weak external driving field with a suitably chosen frequency suffices to accomplish speedy escape. The latter requires passage through a transition state, the formation of which is triggered by permanent feeding of energy from a phonon background into humps of localized energy and elastic interaction of the arising breather solutions. In fact, cooperativity between the units of the chain entailing coordinated energy transfer is shown to be crucial for enhancing the rate of escape in an extremely effective and low-energy cost way where the effects of entropic localization and breather coalescence conspire.

  13. Weak nonlinear coupling of Rossby-Haurwitz waves

    NASA Astrophysics Data System (ADS)

    Becker, G.

    1986-11-01

    The Rossby-Haurwitz waves as solutions of the linearized free barotropic vorticity equation in a spherical coordinate system are in good agreement with the observed ultralong planetary waves of the troposphere. Within an antisymmetric basic flow, as in the middle atmosphere, the solutions become unstable because of mathematical singularities, called 'critical latitudes'. Therefore the nonlinear advection terms have to be considered in such a case. Analytical solutions of a corresponding spectral truncated model demonstrate the weak interaction between the mean flow and the ultralong waves of zonal wavenumbers one to three. The time structures of the planetary waves change from periodic oscillations via vacillations to turbulent character with increasing initial amplitudes. Finally the spectral model is extended by the waves of wavenumber four. The numerical solutions for the periods of the planetary waves within tropospheric and stratospheric basic flow configurations agree with observations.

  14. Spectrum of Mathematical Weaknesses: Related Neuropsychological Correlates.

    PubMed

    Perna, Robert; Loughan, Ashlee R; Le, Jessica; Hertza, Jeremy; Cohen, Morris J

    2015-01-01

    Math disorders have been recognized for as long as language disorders yet have received far less research. Mathematics is a complex construct and its development may be dependent on multiple cognitive abilities. Several studies have shown that short-term memory, working memory, visuospatial skills, processing speed, and various language skills relate to and may facilitate math development and performance. The hypotheses explored in this research were that children who performed worse on math achievement than on Full-Scale IQ would exhibit weaknesses in executive functions, memory, and visuoperceptual skills. Participants included 436 children (27% girls, 73% boys; age range = 5-17 years, M(age) = 9.45 years) who were referred for neuropsychological evaluations due to academic and/or behavioral problems. This article specifically focuses on the spectrum of math weakness rather than clinical disability, which has yet to be investigated in the literature. Results suggest that children with relative weakness to impairments in math were significantly more likely to have cognitive weaknesses to impairments on neuropsychological variables, as compared with children without math weaknesses. Specifically, the math-weak children exhibit a weakness to impairment on measures involving attention, language, visuoperceptual skills, memory, reading, and spelling. Overall, our results suggest that math development is multifaceted. PMID:25117216

  15. Derivation of Reliable Geometries in QM Calculations of DNA Structures: Explicit Solvent QM/MM and Restrained Implicit Solvent QM Optimizations of G-Quadruplexes.

    PubMed

    Gkionis, Konstantinos; Kruse, Holger; Šponer, Jiří

    2016-04-12

    Modern dispersion-corrected DFT methods have made it possible to perform reliable QM studies on complete nucleic acid (NA) building blocks having hundreds of atoms. Such calculations, although still limited to investigations of potential energy surfaces, enhance the portfolio of computational methods applicable to NAs and offer considerably more accurate intrinsic descriptions of NAs than standard MM. However, in practice such calculations are hampered by the use of implicit solvent environments and truncation of the systems. Conventional QM optimizations are spoiled by spurious intramolecular interactions and severe structural deformations. Here we compare two approaches designed to suppress such artifacts: partially restrained continuum solvent QM and explicit solvent QM/MM optimizations. We report geometry relaxations of a set of diverse double-quartet guanine quadruplex (GQ) DNA stems. Both methods provide neat structures without major artifacts. However, each one also has distinct weaknesses. In restrained optimizations, all errors in the target geometries (i.e., low-resolution X-ray and NMR structures) are transferred to the optimized geometries. In QM/MM, the initial solvent configuration causes some heterogeneity in the geometries. Nevertheless, both approaches represent a decisive step forward compared to conventional optimizations. We refine earlier computations that revealed sizable differences in the relative energies of GQ stems computed with AMBER MM and QM. We also explore the dependence of the QM/MM results on the applied computational protocol. PMID:26914292

  16. Derivation of Reliable Geometries in QM Calculations of DNA Structures: Explicit Solvent QM/MM and Restrained Implicit Solvent QM Optimizations of G-Quadruplexes.

    PubMed

    Gkionis, Konstantinos; Kruse, Holger; Šponer, Jiří

    2016-04-12

    Modern dispersion-corrected DFT methods have made it possible to perform reliable QM studies on complete nucleic acid (NA) building blocks having hundreds of atoms. Such calculations, although still limited to investigations of potential energy surfaces, enhance the portfolio of computational methods applicable to NAs and offer considerably more accurate intrinsic descriptions of NAs than standard MM. However, in practice such calculations are hampered by the use of implicit solvent environments and truncation of the systems. Conventional QM optimizations are spoiled by spurious intramolecular interactions and severe structural deformations. Here we compare two approaches designed to suppress such artifacts: partially restrained continuum solvent QM and explicit solvent QM/MM optimizations. We report geometry relaxations of a set of diverse double-quartet guanine quadruplex (GQ) DNA stems. Both methods provide neat structures without major artifacts. However, each one also has distinct weaknesses. In restrained optimizations, all errors in the target geometries (i.e., low-resolution X-ray and NMR structures) are transferred to the optimized geometries. In QM/MM, the initial solvent configuration causes some heterogeneity in the geometries. Nevertheless, both approaches represent a decisive step forward compared to conventional optimizations. We refine earlier computations that revealed sizable differences in the relative energies of GQ stems computed with AMBER MM and QM. We also explore the dependence of the QM/MM results on the applied computational protocol.

  17. Generalized parallel heat transport equations in collisional to weakly collisional plasmas

    NASA Astrophysics Data System (ADS)

    Zawaideh, Emad; Kim, N. S.; Najmabadi, Farrokh

    1988-11-01

    A new set of two-fluid heat-transport equations for heat conduction in collisional to weakly collisional plasmas was derived on the basis of gyrokinetic equations in flux coordinates. In these equations, no restrictions on the anisotropy of the ion distribution function or the collisionality are imposed. In the highly collisional limit, these equations reduce to the classical heat conduction equation of Spitzer and Haerm (1953), while in the weakly collisional limit, they describe a saturated heat flux. Numerical examples comparing these equations with conventional heat transport equations are presented.

  18. Structural features of sequential weak measurements

    NASA Astrophysics Data System (ADS)

    Diósi, Lajos

    2016-07-01

    We discuss the abstract structure of sequential weak measurement (WM) of general observables. In all orders, the sequential WM correlations without postselection yield the corresponding correlations of the Wigner function, offering direct quantum tomography through the moments of the canonical variables. Correlations in spin-1/2 sequential weak measurements coincide with those in strong measurements, they are constrained kinematically, and they are equivalent with single measurements. In sequential WMs with postselection, an anomaly occurs, different from the weak value anomaly of single WMs. In particular, the spread of polarization σ ̂ as measured in double WMs of σ ̂ will diverge for certain orthogonal pre- and postselected states.

  19. Complex weak values in quantum measurement

    SciTech Connect

    Jozsa, Richard

    2007-10-15

    In the weak value formalism of Aharonov et al., the weak value A{sub w} of any observable A is generally a complex number. We derive a physical interpretation of its value in terms of the shift in the measurement pointer's mean position and mean momentum. In particular, we show that the mean position shift contains a term jointly proportional to the imaginary part of the weak value and the rate at which the pointer is spreading in space as it enters the measurement interaction.

  20. Weak side of strong topological insulators

    NASA Astrophysics Data System (ADS)

    Sbierski, Björn; Schneider, Martin; Brouwer, Piet W.

    2016-04-01

    Strong topological insulators may have nonzero weak indices. The nonzero weak indices allow for the existence of topologically protected helical states along line defects of the lattice. If the lattice admits line defects that connect opposite surfaces of a slab of such a "weak-and-strong" topological insulator, these states effectively connect the surface states at opposite surfaces. Depending on the phases accumulated along the dislocation lines, this connection results in a suppression of in-plane transport and the opening of a spectral gap or in an enhanced density of states and an increased conductivity.

  1. Network Coordinator Report

    NASA Technical Reports Server (NTRS)

    Himwich, Ed; Strand, Richard

    2013-01-01

    This report includes an assessment of the network performance in terms of lost observing time for the 2012 calendar year. Overall, the observing time loss was about 12.3%, which is in-line with previous years. A table of relative incidence of problems with various subsystems is presented. The most significant identified causes of loss were electronics rack problems (accounting for about 21.8% of losses), antenna reliability (18.1%), RFI (11.8%), and receiver problems (11.7%). About 14.2% of the losses occurred for unknown reasons. New antennas are under development in the USA, Germany, and Spain. There are plans for new telescopes in Norway and Sweden. Other activities of the Network Coordinator are summarized.

  2. Silver(i) complexes with 1'-(diphenylphosphino)-1-cyanoferrocene: the art of improvisation in coordination.

    PubMed

    Škoch, Karel; Uhlík, Filip; Císařová, Ivana; Štěpnička, Petr

    2016-06-28

    1'-(Diphenylphosphino)-1-cyanoferrocene () reacts with silver(i) halides at a 1 : 1 metal-to-ligand ratio to afford the heterocubane complexes [Ag(μ3-X)(-κP)]4, where X = Cl (), Br (), and I (). In addition, the reaction with AgCl with 2 equiv. of leads to chloride-bridged dimer [(μ-Cl)2{Ag(-κP)2}2] () and, presumably, also to [(μ(P,N)-){AgCl(-κP)}]2 (). While similar reactions with AgCN furnished only the insoluble coordination polymer [(-κP)2Ag(NC)Ag(CN)]n (), those with AgSCN afforded the heterocubane [Ag(-κP)(μ-SCN-S,S,N)]4 () and the thiocyanato-bridged disilver(i) complex [Ag(-κP)2(μ-SCN-S,N)]2 (), thereby resembling reactions in the AgCl- system. Attempted reactions with AgF led to ill-defined products, among which [Ag(-κP)2(μ-HF2)]2 () and [(μ-SiF6){Ag(-κP)2}2] () could be identified. The latter compound was prepared also from Ag2[SiF6] and . Reactions between and AgClO4 or Ag[BF4] afforded disilver complexes [(μ(P,N)-)Ag(ClO4-κO)]2 () and [(μ(P,N)-)Ag(BF4-κF)]2 () featuring pseudolinear Ag(i) centers that are weakly coordinated by the counter anions. A similar reaction with Ag[SbF6] followed by crystallization from ethyl acetate produced an analogous complex, albeit with coordinated solvent, [(μ(P,N)-)Ag(AcOEt-κO)]2[SbF6]2 (). Ultimately, a compound devoid of any additional ligands at the Ag(i) centers, [(μ(P,N)-)Ag]2[B(C6H3(CF3)2-3,5)4]2 (), was obtained from the reaction of with silver(i) tetrakis[3,5-bis(trifluoromethyl)phenyl]borate. The reaction of Ag[BF4] with two equivalents of produced unique coordination polymer [Ag(-κP)(μ(P,N)-)]n[BF4]n (), the structure of which contained one of the phosphinoferrocene ligands coordinated as a P,N-chelate and the other forming a bridge to an adjacent Ag(i) center. All of these compounds were structurally characterized by single-crystal X-ray crystallography, revealing that the lengths of the bonds between silver and its anionic ligand(s) typically exceed the sum of the respective

  3. Coordination of epigenetic events.

    PubMed

    El-Osta, A

    2004-09-01

    During the course of DNA damage a complex repertoire of molecular signals, chromatin determinants and specific transcription factors are set in motion for repair. In many instances, the response pathway can be characterized by profound changes in molecular remodeling and is intimately linked with DNA replication and gene transcription. Our understanding of the molecular pathways has come from scientific developments that represent many disparate disciplines, such as cancer (epi)genetics, chromatin modifications during cellular development and the emerging prominence of epigenetic events in human disease. These multidisciplinary areas reveal a functional relationship and suggest that repair and transcription must coincide in the context of chromatin. We have come to appreciate the repair process and the role of transcriptional components in a sophisticated program of epigenetic regulation, and we have learnt much since the first description of the nucleosome as a spheroid disklike unit. The coordinated and ordered response to DNA damage can specify structures that mobilize and remodel nucleosomes. Investigators will undoubtedly continue to explore the structural and functional states of DNA damage repair and continue to profile the sequence of events and scrutinize the molecular signatures that specify these changes in chromatin dynamics, genomic stability and transcriptional performance. In this special issue, authors have contributed reviews that discuss hypotheses and results regarding DNA damage repair and transcription. The topics covered range from DNA repair in a chromatin environment to the deadly double-strand break, histone modifications to ATP-dependent chromatin remodeling, gene silencing in cancer to apoptosis and regulation of chromatin dynamics by DNA methylation. The scene is set for a new view of damage detection and repair by the coordination of epigenetic states.

  4. Coordinating Group report

    SciTech Connect

    Not Available

    1994-01-01

    In December 1992, western governors and four federal agencies established a Federal Advisory Committee to Develop On-site Innovative Technologies for Environmental Restoration and Waste Management (the DOIT Committee). The purpose of the Committee is to advise the federal government on ways to improve waste cleanup technology development and the cleanup of federal sites in the West. The Committee directed in January 1993 that information be collected from a wide range of potential stakeholders and that innovative technology candidate projects be identified, organized, set in motion, and evaluated to test new partnerships, regulatory approaches, and technologies which will lead to improve site cleanup. Five working groups were organized, one to develop broad project selection and evaluation criteria and four to focus on specific contaminant problems. A Coordinating Group comprised of working group spokesmen and federal and state representatives, was set up to plan and organize the routine functioning of these working groups. The working groups were charged with defining particular contaminant problems; identifying shortcomings in technology development, stakeholder involvement, regulatory review, and commercialization which impede the resolution of these problems; and identifying candidate sites or technologies which could serve as regional innovative demonstration projects to test new approaches to overcome the shortcomings. This report from the Coordinating Group to the DOIT Committee highlights the key findings and opportunities uncovered by these fact-finding working groups. It provides a basis from which recommendations from the DOIT Committee to the federal government can be made. It also includes observations from two public roundtables, one on commercialization and another on regulatory and institutional barriers impeding technology development and cleanup.

  5. Biological monitoring of chlorinated hydrocarbon solvents

    SciTech Connect

    Monster, A.C.

    1986-08-01

    The possibility of biological monitoring of exposure to some volatile, halogenated hydrocarbons will be discussed. Most of these agents are widely used as solvents. All agents act on the nervous system as narcotics and differ widely in toxicity. Most of the solvents undergo biotransformation to metabolites. This allows biological assessment of exposure by measurement of the solvent and/or metabolites in exhaled air, blood, and/or urine. However, the same metabolites may occur with exposure to different chlorinated hydrocarbons, eg, trichloroethanol and trichloroacetic acid from exposure to trichloroethene, tetrachloroethene, and 1,1,1-trichloroethane. On the other hand, these agents differ widely in the percentage that is metabolized. There are large gaps in our knowledge, however, and much research will have to be carried out before even tentative data can be established for most of the solvents.

  6. "Solvent Effects" in 1H NMR Spectroscopy.

    ERIC Educational Resources Information Center

    Cavaleiro, Jose A. S.

    1987-01-01

    Describes a simple undergraduate experiment in chemistry dealing with the "solvent effects" in nuclear magnetic resonance (NMR) spectroscopy. Stresses the importance of having students learn NMR spectroscopy as a tool in analytical chemistry. (TW)

  7. United States Air Force Wipe Solvent Testing

    NASA Technical Reports Server (NTRS)

    Hornung, Steven D.; Beeson, Harold D.

    2000-01-01

    The Wright-Patterson Air Force Base (WPAFB), as part of the Air Force Material Command, requested that NASA Johnson Space Center (JSC) White Sands Test Facility (WSTF) conduct testing and analyses in support of the United States Air Force Wipe Solvent Development Project. The purpose of the wipe solvent project is to develop an alternative to be used by Air Force flight line and maintenance personnel for the wipe cleaning of oxygen equipment. This report provides material compatibility, liquid oxygen (LOX) mechanical impact, autogenous ignition temperature (AIT), and gauge cleaning test data for some of the currently available solvents that may be used to replace CFC-113 and methyl chloroform. It provides data from previous WSTF test programs sponsored by the Naval Sea Systems Command, the Kennedy Space Center, and other NASA programs for the purpose of assisting WP AFB in identifying the best alternative solvents for validation testing.

  8. Used lubricating oil recycling using hydrocarbon solvents.

    PubMed

    Hamad, Ahmad; Al-Zubaidy, Essam; Fayed, Muhammad E

    2005-01-01

    A solvent extraction process using new hydrocarbon solvents was employed to treat used lubricant oil. The solvents used were liquefied petroleum gas (LPG) condensate and stabilized condensate. A demulsifier was used to enhance the treatment process. The extraction process using stabilized condensate demonstrated characteristics that make it competitive with existing used oil treatment technologies. The process is able to reduce the asphaltene content of the treated lubricating oil to 0.106% (w/w), the ash content to 0.108%, and the carbon residue to 0.315% with very low levels of contaminant metals. The overall yield of oil is 79%. The treated used oil can be recycled as base lubricating oil. The major disadvantage of this work is the high temperature of solvent recovery. Experimental work and results are presented in detail. PMID:15627468

  9. Implicit solvent methods for free energy estimation

    PubMed Central

    Decherchi, Sergio; Masetti, Matteo; Vyalov, Ivan; Rocchia, Walter

    2014-01-01

    Solvation is a fundamental contribution in many biological processes and especially in molecular binding. Its estimation can be performed by means of several computational approaches. The aim of this review is to give an overview of existing theories and methods to estimate solvent effects giving a specific focus on the category of implicit solvent models and their use in Molecular Dynamics. In many of these models, the solvent is considered as a continuum homogenous medium, while the solute can be represented at the atomic detail and at different levels of theory. Despite their degree of approximation, implicit methods are still widely employed due to their trade-off between accuracy and efficiency. Their derivation is rooted in the statistical mechanics and integral equations disciplines, some of the related details being provided here. Finally, methods that combine implicit solvent models and molecular dynamics simulation, are briefly described. PMID:25193298

  10. Innovative Technologies for Chlorinated Solvent Remediation

    NASA Astrophysics Data System (ADS)

    Pennell, Kurt D.; Cápiro, Natalie L.

    2014-07-01

    The following sections are included: * INTRODUCTION * TRADITIONAL REMEDIATION TECHNOLOGIES (1980s) * RESEARCH AND DEVELOPMENT OF INNOVATIVE REMEDIATION TECHNOLOGIES (1990s-2000s) * CURRENT TRENDS IN CHLORINATED SOLVENT REMEDIATION (2010s) * CLOSING THOUGHTS * REFERENCES

  11. On a new coordinate system with astrophysical application: Spiral coordinates

    NASA Astrophysics Data System (ADS)

    Campos, L. M. B. C.; Gil, P. J. S.

    In this presentation are introduced spiral coordinates, which are a particular case of conformal coordinates, i.e. orthogonal curvelinear coordinates with equal factors along all coordinate axis. The spiral coordinates in the plane have as coordinate curves two families of logarithmic spirals, making a constant angle, respectively phi and pi / 2-phi, with all radial lines, where phi is a parameter. They can be obtained from a complex function, representing a spiral potential flow, due to the superposition of a source/sink with a vortex; the parameter phi in this case specifies the ratio of the ass flux of source/sink to the circulation of the vortex. Regardless of hydrodynamical or other interpretations, spiral coordinates are particulary convenient in situation where physical quantities vary only along a logarithmicspiral. The example chosen is the propagation of Alfven waves along a logarithmic spiral, as an approximation to Parker's spiral. The equation of dissipative MHD are written in spiral coordinates, and eliminated to specify the Alfven wave equation in spiral coordinates; the latter is solved exactly in terms of Bessel functions, and the results analyzed for values of the parameters corresponding to the solar wind.

  12. Effect of Ligand Structural Isomerism in Formation of Calcium Coordination Networks

    SciTech Connect

    Plonka A. M.; Parise J.; Banerjee, D.

    2012-03-28

    Using different structural isomers (2,5-; 2,4-; 2;6-; 3,4-; 3,5-) of pyridinedicarboxylic acid, nine calcium-based coordination networks were synthesized under hydro-/solvothermal conditions and/or were produced via solvent recrystallization of previously synthesized compounds. The coordination networks reported were characterized using single crystal X-ray diffraction and thermal methods. They show diverse structural topologies, depending on the ligand geometry and coordinated solvent molecules, with inorganic connectivity motifs ranging from isolated octahedra to infinite chains, layer and a three-dimensional dense framework. The as-synthesized and desolvated networks further show structural transformation to hydrated phases through dissolution/reformation pathways. The process is likely driven by the high hydration energy of the calcium metal center.

  13. Water as a Solvent for Life

    NASA Technical Reports Server (NTRS)

    Pohorille, Andrew; Pratt, Lawrence R.

    2015-01-01

    "Follow the water" is our basic strategy in searching for life in the universe. The universality of water as the solvent for living systems is usually justified by arguing that water supports the rich organic chemistry that seeds life, but alternative chemistries are possible in other organic solvents. Here, other, essential criteria for life that have not been sufficiently considered so far, will be discussed.

  14. Screening evaluation of alternative cleaning solvents

    SciTech Connect

    Nigrey, P.J.

    1991-01-01

    The cleaning efficiency of five alternative solvents for chlorofluorocarbons (CFCs) and chlorohydrocarbons (CHCs) used in the manufacture of certain electronic components was studied. These solvents were evaluated in the first phase of a two-phase program to remove various manufacturing contaminants such as oils, greases, mold release, and body oils. Results have shown that EXXATE 1000 and EC-7 were able to effectively remove these contaminants from copper board substrates. 4 refs., 5 figs., 1 tab.

  15. Dispersion of carbon nanotubes using organic solvents.

    PubMed

    Dumonteil, S; Demortier, A; Detriche, S; Raes, C; Fonseca, A; Rühle, M; Nagy, J B

    2006-05-01

    Phenyl ethyl alcohol was used for fast and stable dispersion of carbon nanotubes. This solvent, more effective than ethanol and toluene, allows easy dispersion of carbon nanotubes for TEM characterization. For TEM grids prepared at high dilution, it is possible to observe each tube separately. Applying that solvent, it was possible to measure the length, the diameter and the solubility of different carbon nanotubes samples.

  16. Method of stripping metals from organic solvents

    DOEpatents

    Todd, Terry A.; Law, Jack D.; Herbst, R. Scott; Romanovskiy, Valeriy N.; Smirnov, Igor V.; Babain, Vasily A.; Esimantovski, Vyatcheslav M.

    2009-02-24

    A new method to strip metals from organic solvents in a manner that allows for the recycle of the stripping agent. The method utilizes carbonate solutions of organic amines with complexants, in low concentrations, to strip metals from organic solvents. The method allows for the distillation and reuse of organic amines. The concentrated metal/complexant fraction from distillation is more amenable to immobilization than solutions resulting from current practice.

  17. Biofiltration of solvent vapors from air

    SciTech Connect

    Oh, Young-sook.

    1993-01-01

    For various industrial solvent vapors, biofiltration promises to offer a cost-effective emission control technology. Exploiting the full potential of this technology will help attain the goals of the Clean Air Act Amendments of 1990. Concentrating on large volumes of volatile industrial solvents, stable multicomponent microbial enrichments capable of growing a mineral medium with solvent vapors as their only source of carbon and energy were obtained from soil and sewage sludge. These consortia were immobilized on an optimized porous solid support (ground peat moss and perlite). The biofilter material was packed in glass columns connected to an array of pumps and flow meters that allowed the independent variation of superficial velocity and solvent vapor concentrations. In various experiments, single solvents, such as methanol, butanol, acetonitrile, hexane and nitrobenzene, and solvent mixtures, such as benzene-toluene-xylene (BTX) and chlorobenzene-o-dichlorobenzene (CB/DCB) were biofiltered with rates ranging from 15 to334 g solvent removed per m[sup 3] filter volume /h. Pressure drops were low to moderate (0-10 mmHg/m) and with periodic replacement of moisture, the biofiltration activity could be maintained for a period of several months. The experimental data on methanol biofiltration were subjected to mathematical analysis and modeling by the group of Dr. Baltzis at NJIT for a better understanding and a possible scale up of solvent vapor biofilters. In the case of chlorobenzenes and nitrobenzene, the biofilter columns had to be operated with water recirculation in a trickling filter mode. To prevent inactivation of the trickling filter by acidity during CB/DCB removal, pH control was necessary, and the removal rate of CB/DCB was strongly influenced by the flow rate of the recyling water. Nitrobenzene removal in a trickling filter did not require pH control, since the nitro group was reduced and volatilized as ammonia.

  18. Solvent extraction behaviour of thiocyanic acid.

    PubMed

    Jurriaanse, A; Kemp, D M

    1968-11-01

    The solvent extraction behaviour of thiocyanic acid with isobutyl methyl ketone and xylene as solvents is described. In the ketone system the thiocyanic acid is solvated in the organic phase to give a complex with a proposed composition of HSCN. 2IBMK. Deviations from ideal behaviour, which can be attributed to variations in the activity coefficient of the acid in the aqueous phase, are shown.

  19. Competitive solvent-molecule interactions govern primary processes of diphenylcarbene in solvent mixtures

    PubMed Central

    Knorr, Johannes; Sokkar, Pandian; Schott, Sebastian; Costa, Paolo; Thiel, Walter; Sander, Wolfram; Sanchez-Garcia, Elsa; Nuernberger, Patrick

    2016-01-01

    Photochemical reactions in solution often proceed via competing reaction pathways comprising intermediates that capture a solvent molecule. A disclosure of the underlying reaction mechanisms is challenging due to the rapid nature of these processes and the intricate identification of how many solvent molecules are involved. Here combining broadband femtosecond transient absorption and quantum mechanics/molecular mechanics simulations, we show for one of the most reactive species, diphenylcarbene, that the decision-maker is not the nearest solvent molecule but its neighbour. The hydrogen bonding dynamics determine which reaction channels are accessible in binary solvent mixtures at room temperature. In-depth analysis of the amount of nascent intermediates corroborates the importance of a hydrogen-bonded complex with a protic solvent molecule, in striking analogy to complexes found at cryogenic temperatures. Our results show that adjacent solvent molecules take the role of key abettors rather than bystanders for the fate of the reactive intermediate. PMID:27708264

  20. Competitive solvent-molecule interactions govern primary processes of diphenylcarbene in solvent mixtures

    NASA Astrophysics Data System (ADS)

    Knorr, Johannes; Sokkar, Pandian; Schott, Sebastian; Costa, Paolo; Thiel, Walter; Sander, Wolfram; Sanchez-Garcia, Elsa; Nuernberger, Patrick

    2016-10-01

    Photochemical reactions in solution often proceed via competing reaction pathways comprising intermediates that capture a solvent molecule. A disclosure of the underlying reaction mechanisms is challenging due to the rapid nature of these processes and the intricate identification of how many solvent molecules are involved. Here combining broadband femtosecond transient absorption and quantum mechanics/molecular mechanics simulations, we show for one of the most reactive species, diphenylcarbene, that the decision-maker is not the nearest solvent molecule but its neighbour. The hydrogen bonding dynamics determine which reaction channels are accessible in binary solvent mixtures at room temperature. In-depth analysis of the amount of nascent intermediates corroborates the importance of a hydrogen-bonded complex with a protic solvent molecule, in striking analogy to complexes found at cryogenic temperatures. Our results show that adjacent solvent molecules take the role of key abettors rather than bystanders for the fate of the reactive intermediate.

  1. Process for solvent refining of coal using a denitrogenated and dephenolated solvent

    DOEpatents

    Garg, Diwakar; Givens, Edwin N.; Schweighardt, Frank K.

    1984-01-01

    A process is disclosed for the solvent refining of non-anthracitic coal at elevated temperatures and pressure in a hydrogen atmosphere using a hydrocarbon solvent which before being recycled in the solvent refining process is subjected to chemical treatment to extract substantially all nitrogenous and phenolic constituents from the solvent so as to improve the conversion of coal and the production of oil in the solvent refining process. The solvent refining process can be either thermal or catalytic. The extraction of nitrogenous compounds can be performed by acid contact such as hydrogen chloride or fluoride treatment, while phenolic extraction can be performed by caustic contact or contact with a mixture of silica and alumina.

  2. 78 FR 73819 - Forest Resource Coordinating Committee

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-12-09

    ... Forest Service Forest Resource Coordinating Committee AGENCY: Forest Service, USDA. ACTION: Notice of...-18, 2013 meeting of the Forest Resource Coordinating Committee due to the Government partial shutdown... INFORMATION CONTACT: Maya Solomon, Forest Resource Coordinating Committee Program Coordinator; by phone...

  3. Molecular accessibility in solvent swelled coal

    SciTech Connect

    Kispert, L.D.

    1991-08-01

    Research continued on the determination of pore size and number distribution changes after swelling the coal samples with various solvents. A paper has just been submitted to the journal Fuel on the Low temperature Swelling of Argonne Premium Coal samples using solvents of varying polarity. The variation in the shape of the pore was followed as a function of temperature and swelling solvent polarity. This change in pore structure was attributed to break-up of the hydrogen bonding network in coal by polar solvents. The modification in pore shape from spherical to cylindrical was attributed to anisotropy in hydrogen bond densities. A copy of this paper has been attached to this report. Wojciech Sady has determine the structural changes in the pores that occur when APCS coal is dehydrated prior to swelling with polar solvents. These changes are different from those that occur in the absence of prior dehydration. He has also completed a study on the variation in the hydrogen bonding character of the pore wall as the coals are swelled with various polar solvents. A statistical analysis of the data is currently underway to determine important trends in his data. 9 refs.

  4. Solvent dependent photophysical properties of dimethoxy curcumin

    NASA Astrophysics Data System (ADS)

    Barik, Atanu; Indira Priyadarsini, K.

    2013-03-01

    Dimethoxy curcumin (DMC) is a methylated derivative of curcumin. In order to know the effect of ring substitution on photophysical properties of curcumin, steady state absorption and fluorescence spectra of DMC were recorded in organic solvents with different polarity and compared with those of curcumin. The absorption and fluorescence spectra of DMC, like curcumin, are strongly dependent on solvent polarity and the maxima of DMC showed red shift with increase in solvent polarity function (Δf), but the above effect is prominently observed in case of fluorescence maxima. From the dependence of Stokes' shift on solvent polarity function the difference between the excited state and ground state dipole moment was estimated as 4.9 D. Fluorescence quantum yield (ϕf) and fluorescence lifetime (τf) of DMC were also measured in different solvents at room temperature. The results indicated that with increasing solvent polarity, ϕf increased linearly, which has been accounted for the decrease in non-radiative rate by intersystem crossing (ISC) processes.

  5. Solvent dependent photophysical properties of dimethoxy curcumin.

    PubMed

    Barik, Atanu; Indira Priyadarsini, K

    2013-03-15

    Dimethoxy curcumin (DMC) is a methylated derivative of curcumin. In order to know the effect of ring substitution on photophysical properties of curcumin, steady state absorption and fluorescence spectra of DMC were recorded in organic solvents with different polarity and compared with those of curcumin. The absorption and fluorescence spectra of DMC, like curcumin, are strongly dependent on solvent polarity and the maxima of DMC showed red shift with increase in solvent polarity function (Δf), but the above effect is prominently observed in case of fluorescence maxima. From the dependence of Stokes' shift on solvent polarity function the difference between the excited state and ground state dipole moment was estimated as 4.9 D. Fluorescence quantum yield (φ(f)) and fluorescence lifetime (τ(f)) of DMC were also measured in different solvents at room temperature. The results indicated that with increasing solvent polarity, φ(f) increased linearly, which has been accounted for the decrease in non-radiative rate by intersystem crossing (ISC) processes. PMID:23314392

  6. Solvent Extraction and Ion Exchange in Radiochemistry

    NASA Astrophysics Data System (ADS)

    Skarnemark, G.

    In 1805, Bucholz extracted uranium from a nitric acid solution into ether and back-extracted it into pure water. This is probably the first reported solvent-extraction investigation. During the following decades, the distribution of neutral compounds between aqueous phases and pure solvents was studied, e.g., by Peligot, Berthelot and Jungfleisch, and Nernst. Selective extractants for analytical purposes became available during the first decades of the twentieth century. From about 1940, extractants such as organophosphorous esters and amines were developed for use in the nuclear fuel cycle. This connection between radiochemistry and solvent-extraction chemistry made radiochemists heavily involved in the development of new solvent extraction processes, and eventually solvent extraction became a major separation technique in radiochemistry. About 160 years ago, Thompson and Way observed that soil can remove potassium and ammonium ions from an aqueous solution and release calcium ions. This is probably the first scientific report on an ion-exchange separation. The first synthesis of the type of organic ion exchangers that are used today was performed by Adams and Holmes in 1935. Since then, ion-exchange techniques have been used extensively for separations of various radionuclides in trace as well as macro amounts. During the last 4 decades, inorganic ion exchangers have also found a variety of applications. Today, solvent extraction as well as ion exchange are used extensively in the nuclear industry and for nuclear, chemical, and medical research. Some of these applications are discussed in the chapter.

  7. Weak-field general relativistic dynamics and the Newtonian limit

    NASA Astrophysics Data System (ADS)

    Cooperstock, F. I.

    2016-01-01

    We show that the generally held view that the gravity of weak-field nonrelativistic-velocity sources being invariably almost equivalent to Newtonian gravity (NG) (the “Newtonian limit” approach) is in some instances misleading and in other cases incorrect. A particularly transparent example is provided by comparing the Newtonian and general relativistic analyses of a simple variant of van Stockum’s infinite rotating dust cylinder. We show that some very recent criticisms of our work that had been motivated by the Newtonian limit approach were incorrect and note that no specific errors in our work were found in the critique. In the process, we underline some problems that arise from inappropriate coordinate transformations. As further support for our methodology, we note that our weak-field general relativistic treatment of a model galaxy was vindicated recently by the observations of Xu et al. regarding our prediction that the Milky Way was 19-21 kpc in radius as opposed to the commonly held view that the radius was 15 kpc.

  8. Caustic-Side Solvent Extraction: Chemical and Physical Properties of the Optimized Solvent

    SciTech Connect

    Delmau, L.H.

    2002-10-08

    This work was undertaken to optimize the solvent used in the Caustic Side Solvent Extraction (CSSX) process and to measure key chemical and physical properties related to its performance in the removal of cesium from the alkaline high-level salt waste stored in tanks at the Savannah River Site. The need to adjust the solvent composition arose from the prior discovery that the previous baseline solvent was supersaturated with respect to the calixarene extractant. The following solvent-component concentrations in Isopar{reg_sign} L diluent are recommended: 0.007 M calix[4]arene-bis(tert-octylbenzo-crown-6) (BOBCalixC6) extractant, 0.75 M 1-(2,2,3,3-tetrafluoropropoxy)-3-(4-sec-butylphenoxy)-2-propanol (Cs-7SB) phase modifier, and 0.003 M tri-n-octylamine (TOA) stripping aid. Criteria for this selection included BOBCalixC6 solubility, batch cesium distribution ratios (D{sub Cs}), calculated flowsheet robustness, third-phase formation, coalescence rate (dispersion numbers), and solvent density. Although minor compromises within acceptable limits were made in flowsheet robustness and solvent density, significant benefits were gained in lower risk of third-phase formation and lower solvent cost. Data are also reported for the optimized solvent regarding the temperature dependence of D{sub Cs} in extraction, scrubbing, and stripping (ESS); ESS performance on recycle; partitioning of BOBCalixC6, Cs-7SB, and TOA to aqueous process solutions; partitioning of organic anions; distribution of metals; solvent phase separation at low temperatures; solvent stability to elevated temperatures; and solvent density and viscosity. Overall, the technical risk of the CSSX process has been reduced by resolving previously identified issues and raising no new issues.

  9. Influence of solvent polarity on preferential solvation of molecular recognition probes in solvent mixtures.

    PubMed

    Amenta, Valeria; Cook, Joanne L; Hunter, Christopher A; Low, Caroline M R; Vinter, Jeremy G

    2012-12-13

    The association constants for formation of 1:1 complexes between a H-bond acceptor, tri-n-butylphosphine oxide, and a H-bond donor, 4-phenylazophenol, have been measured in a range of different solvent mixtures. Binary mixtures of n-octane and a more polar solvent (ether, ester, ketone, nitrile, sulfoxide, tertiary amide, and halogenated and aromatic solvents) have been investigated. Similar behavior was observed in all cases. When the concentration of the more polar solvent is low, the association constant is identical to that observed in pure n-octane. Once a threshold concentration of the more polar solvent in reached, the logarithm of the association constant decreases in direct proportion to the logarithm of the concentration of the more polar solvent. This indicates that one of the two solutes is preferentially solvated by the more polar solvent, and it is competition with this solvation equilibrium that determines the observed association constant. The concentration of the more polar solvent at which the onset of preferential solvation takes place depends on solvent polarity: 700 mM for toluene, 60 mM for 1,1,2,2-tetrachloroethane, 20 mM for the ether, ester, ketone, and nitrile, 0.2 mM for the tertiary amide, and 0.1 mM for the sulfoxide solvents. The results can be explained by a simple model that considers only pairwise interactions between specific sites on the surfaces of the solutes and solvents, which implies that the bulk properties of the solvent have little impact on solvation thermodynamics. PMID:23190174

  10. Competition between weak localization and ballistic transport.

    PubMed

    Tian, Chushun

    2009-06-19

    High-frequency transport in perfect periodic dielectric cylinder arrays is studied. We analytically calculate the diffusive-ballistic transport crossover, which displays the competition between weak localization and ballistic transport. PMID:19659008

  11. Sodium in weak G-band giants

    NASA Technical Reports Server (NTRS)

    Drake, Jeremy J.; Lambert, David L.

    1994-01-01

    Sodium abundances have been determined for eight weak G-band giants whose atmospheres are greatly enriched with products of the CN-cycling H-burning reactions. Systematic errors are minimized by comparing the weak G-band giants to a sample of similar but normal giants. If, further, Ca is selected as a reference element, model atmosphere-related errors should largely be removed. For the weak-G-band stars (Na/Ca) = 0.16 +/- 0.01, which is just possibly greater than the result (Na/Ca) = 0.10 /- 0.03 from the normal giants. This result demonstrates that the atmospheres of the weak G-band giants are not seriously contaminated with products of ON cycling.

  12. Parametric instabilities in weakly magnetized plasma

    SciTech Connect

    Weatherall, J.C.; Goldman, M.V.; Nicholson, D.R.

    1981-05-15

    Parametric instabilities in a weakly magnetized plasma are discussed. The results are applied to waves excited by electron streams which travel outward from the Sun along solar-wind magnetic field lines, as in a type III solar radio burst.

  13. Sensor/amplifier for weak light sources

    NASA Technical Reports Server (NTRS)

    Desmet, D. J.; Jason, A. J.; Parr, A. C.

    1980-01-01

    Light sensor/amplifier circuit detects weak light converts it into strong electrical signal in electrically noisy environment. Circuit is relatively simple and uses inexpensive, readily available components. Device is useful in such applications as fire detection and photographic processing.

  14. Experimental studies of weakly coupled superconductors (Review)

    NASA Astrophysics Data System (ADS)

    Dmitrenko, I. M.

    2004-07-01

    A review is given of the main experimental results obtained in research on weakly coupled superconductors after 1964 at the Institute for Low Temperature Physics and Engineering of the National Academy of Sciences of Ukraine, Kharkov (ILTPE).

  15. Coordination Assembly of Discoid Nanoparticles.

    PubMed

    Hirai, Kenji; Yeom, Bongjun; Chang, Shu-Hao; Chi, Hang; Mansfield, John F; Lee, Byeongdu; Lee, Sungsik; Uher, Ctirad; Kotov, Nicholas A

    2015-07-27

    Supramolecular chemistry utilizes coordination bonds to assemble molecular building blocks into a variety of sophisticated constructs. However, traditional coordination assemblies are based on organic compounds that have limited ability to transport charge. Herein, we describe coordination assembly of anisotropic FeS2 pyrite nanoparticles (NPs) that can facilitate charge transport. Zn(2+) ions form supramolecular complexes with carboxylate end-groups on NP surface, leading to multiparticle sheets with liquid-crystal-like organization. Conductivity and Hall carrier mobility of the p-type layered semiconductor films with Zn(2+) coordination bridging exceed those known for coordination compounds, some by several orders of magnitude. The nanoscale porosity of the assembled sheets combined with fast hole transport leads to high electrocatalytic activity of the NP films. The coordination assembly of NPs embraces the versatility of several types of building blocks and opens a new design space for self-organized materials combining nanoscale and supramolecular structural motifs.

  16. Series of solvent-induced single-crystal to single-crystal transformations with different sizes of solvent molecules.

    PubMed

    He, Yuan-Chun; Yang, Jin; Liu, Ying-Ying; Ma, Jian-Fang

    2014-07-21

    A highly stable soft porous coordination polymer (PCP), namely [Cu3(TP)4(N3)2(DMF)2]·2H2O·2DMF (1), has been synthesized via an in situ synthesis of 4-tetrazole pyridine (TP) under solvothermal conditions (DMF = N,N'-dimethylformamide). Remarkably, the solvent molecules in 1 can be respectively exchanged with cyclohexane (C6H12), cyclopentane (C5H10), decahydronaphthalene (C10H18), 1,4-dioxane (C4H8O2), and tetrahydropyrane (C5H10O) in single-crystal to single-crystal (SCSC) manners to yield [Cu3(TP)4(N3)2(DMF)2]·3C6H12 (1a), [Cu3(TP)4(N3)2(DMF)2]·2C5H10 (1b), [Cu3(TP)4(N3)2(DMF)2]·H2O·C10H18 (1c), [Cu3(TP)4(N3)2(DMF)2]·C4H8O2 (1d), [Cu3(TP)4(N3)2]·3C4H8O2 (1e), and [Cu3(TP)4(N3)2]·2H2O·C5H10O (1f). Further, the occluded cyclohexane molecules in 1a can be removed by heating to give its porous guest-free form [Cu3(TP)4(N3)2(DMF)2] (1g). Particularly, in water, 1 can lose its coordinated N3(-) anions to generate [Cu(TP)2(H2O)4]·4H2O (1h). More interestingly, the soft PCP (1) demonstrates the guest selectivity for the cycloalkane solvents, namely cyclohexane, cyclopentane, and decahydronaphthalene, in SCSC manners for the first time, attributed to the synergy effect between the size and geometry of the solvent and the shape of the framework cavity. Moreover, the desolvated samples of 1e show the highly selective gas adsorption of CO2 over N2, indicating its potential application in the separation of the CO2/N2 mixture.

  17. Some Topics in Weak and Electromagnetic Interactions

    NASA Astrophysics Data System (ADS)

    Bjorken, James D.

    1982-01-01

    The following sections are included: * INTRODUCTION * LECTURE I QUANTUM-ELECTRODYNAMICS TESTS; TESTS OF Jμ Jμ STRUCTURE IN WEAK INTERACTIONS; HIGHER-ORDER WEAK INTERACTIONS * LECTURE II PHENOMENOLOGY OF DEEP-INELASTIC PROCESSES; NO FINAL-STATE HADRONS OBSERVED * LECTURE III LIGHT-CONE COMMUTATORS; MODELS OF THE STRUCTURE FUNCTIONS * LECTURE IV HADRON FINAL STATES IN DEEP-INELASTIC PROCESSES; GENERAL CONSIDERATIONS * LECTURE V INCLUSIVE PROCESSES AT VERY HIGH TRANSVERSE MOMENTUM * REFERENCES

  18. Deterministic implementation of weak quantum cubic nonlinearity

    SciTech Connect

    Marek, Petr; Filip, Radim; Furusawa, Akira

    2011-11-15

    We propose a deterministic implementation of weak cubic nonlinearity, which is a basic building block of a full-scale continuous-variable quantum computation. Our proposal relies on preparation of a specific ancillary state and transferring its nonlinear properties onto the desired target by means of deterministic Gaussian operations and feed forward. We show that, despite the imperfections arising from the deterministic nature of the operation, the weak quantum nonlinearity can be implemented and verified with the current level of technology.

  19. Looking for heavier weak bosons with DUMAND

    NASA Technical Reports Server (NTRS)

    Brown, R. W.; Stecker, F. W.

    1980-01-01

    One or more heavier weak bosons may coexist with the standard weak boson, a broad program may be laid out for a search for the heavier W's via change in the total cross section due to the additional propagator, a concomitant search, and a subsequent search for significant antimatter in the universe involving the same annihilation, but being independent of possible neutrino oscillations. The program is likely to require detectors sensitive to higher energies, such as acoustic detectors.

  20. Electromagnetic and Weak transitions in light nuclei

    SciTech Connect

    M. Viviani; L.E. Marcucci; A. Kievsky; S. Rosati; R. Schiavilla

    2002-09-01

    Recent advances in the study of the p -- d radiative and mu -- {sup 3}He weak capture processes by our group are presented and discussed. The trinucleon bound and scattering states have been obtained from variational calculations by expanding the corresponding wave functions in terms of correlated hyper-spherical harmonic functions. The electromagnetic and weak transition currents include one- and two-body operators. The accuracy achieved in these calculations allows for interesting comparisons with experimental data.

  1. Toroidal equilibria in spherical coordinates

    SciTech Connect

    Tsui, K. H.

    2008-11-15

    The standard Grad-Shafranov equation for axisymmetric toroidal plasma equilibrium is customary expressed in cylindrical coordinates with toroidal contours, and through which benchmark equilibria are solved. An alternative approach to cast the Grad-Shafranov equation in spherical coordinates is presented. This equation, in spherical coordinates, is examined for toroidal solutions to describe low {beta} Solovev and high {beta} plasma equilibria in terms of elementary functions.

  2. CHEMICAL STABILITY OF POLYPHENYLENE SULFIDE IN THE NEXT GENERATION SOLVENT FOR CAUSTIC-SIDE SOLVENT EXTRACTION

    SciTech Connect

    Fondeur, F.; Fink, S.

    2011-12-08

    The Office of Waste Processing, within the Office of Technology Innovation and Development, is funding the development of an enhanced solvent for deployment at the Savannah River Site for removal of cesium from High Level Waste. For simplicity, this solvent is referred to as the Next Generation Solvent (NGS). The technical effort is collaboration between Oak Ridge National Laboratory (ORNL), Savannah River National Laboratory (SRNL), and Argonne National Laboratory. The initial deployment target envisioned for the technology was within the Modular Caustic-Side Solvent Extraction Unit (MCU). Deployment of a new chemical within an existing facility requires verification that the chemical components are compatible with the installed equipment. In the instance of a new organic solvent, the primary focus is on compatibility of the solvent with polyphenylene sulfide (PPS), the polymer used in the coalescers within MCU. This report provides the data from exposing PPS polymer to NGS. The test was conducted over a three month period. PPS is remarkably stable in the presence of the next generation solvent. Testing showed no indication of swelling or significant leaching. Preferential sorption of the Modifier on PPS was observed but the same behavior occurs with the baseline solvent. Therefore, PPS coalescers exposed to the NGS are expected to perform comparably to those in contact with the baseline solvent.

  3. Carving a 1D Co(II)-carboranylcarboxylate system by using organic solvents to create stable trinuclear molecular analogues: complete structural and magnetic studies.

    PubMed

    Fontanet, Mònica; Rodríguez, Montserrat; Fontrodona, Xavier; Romero, Isabel; Teixidor, Francesc; Viñas, Clara; Aliaga-Alcalde, Núria

    2016-07-01

    This work presents a straightforward methodology to achieve small linear trinuclear molecules based on the Co(II)-carboranylcarboxylate system obtained by carving a 1D polynuclear analogous system with the use of diethylether. The reaction of the carboranylcarboxylic ligand, 1-CH3-2-CO2H-1,2-closo-C2B10H10 (LH) with different cobalt salts leads to the polynuclear compound [Co2(μ-H2O)(1-CH3-2-CO2-1,2-closo-C2B10H10)4(THF)4], and the polymeric [Co(μ-H2O)(1-CH3-2-CO2-1,2-closo-C2B10H10)2]n(H2O)n. This latter 1D chain has been obtained by an unprecedented synthetic strategy for the isolation of cobalt(ii) compounds. [Co3(μ-H2O)2(1-CH3-2-CO2-1,2-closo-C2B10H10)6(H2O)2(C4H10O)2], is formed by the dissociation of the polymeric structure that forms when a mild coordinating solvent such as diethylether is added. These compounds have been characterized by analytical and spectroscopic techniques. X-ray analysis of and revealed that presents a dinuclear structure whereas is trinuclear; in both cases a six-coordinated Co(II) compound with water molecules bridging each of the two Co(II) centres has been observed. The magnetic properties of and show a weak antiferromagnetic behaviour, respectively, between the Co(II) centres mediated by two carboxylate ligands and a molecule of water. PMID:27301436

  4. Stability of the Caustic-Side Solvent Extraction (CSSX) Process Solvent: Effect of High Nitrite on Solvent Nitration

    SciTech Connect

    Bonnesen, P.V.

    2002-06-26

    The purpose of this investigation was to determine whether nitrated organic compounds could be formed during operation of the Caustic-Side Solvent Extraction (CSSX) process, and whether such compounds would present a safety concern. The CSSX process was developed to remove cesium from alkaline high-level salt waste stored at the US Department of Energy Savannah River Site (SRS). The solvent is composed of the cesium extractant calix[4]arene-bis-(4-tert-octylbenzo-crown-6) (BOBCalixC6), a fluorinated alcohol phase modifier, tri-n-octylamine (TOA), and an isoparaffinic diluent (Iospar{reg_sign}). During the CSSX process, the solvent is expected to be exposed to high concentrations of nitrate and nitrite dissolved in the alkaline waste feed. The solvent will also be exposed to dilute (50 mM) nitric acid solutions containing low concentrations of nitrite during scrubbing, followed by stripping with 1 mM nitric acid. The solvent is expected to last for one year of plant operation, and the temperatures the solvent may experience during the process could range from as low as 15 C to as high as 35 C. Excursions from standard process conditions could result in the solvent experiencing higher temperatures, as well as concentrations of nitrate, nitrite, and most importantly nitric acid, that exceed normal operating conditions. Accordingly, conditions may exist where nitration reactions involving the solvent components, possibly leading to other chemical reactions stemming from nitration reactions, could occur. To model such nitration reactions, the solvent was exposed to the types of nitrate- and nitrite-containing solutions that might be expected to be encountered during the process (even under off-normal conditions), as a function of time, temperature, and concentration of nitrate, nitrite, and nitric acid. The experiments conducted as part of this report were designed to examine the more specific effect that high nitrite concentrations could have on forming nitrated

  5. Ulysses: UVCS Coordinated Observations

    NASA Technical Reports Server (NTRS)

    Suess, S. T.; Poletto, G.; Corti, G.; Simnett, G.; Noci, G.; Romoli, M.; Kohl, J.; Goldstein, B.

    1998-01-01

    We present results from coordinated observations in which instruments on Solar and Heliospheric Observatory (SOHO) and Ulysses were used to measure the density and flow speed of plasma at the Sun and to again measure the same properties of essentially the same plasma in the solar wind. Plasma was sampled by Ultraviolet Coronagraph Spectrometer (UVCS) at 3.5 and 4.5 solar radii and by Ulysses/SWOOPS at 5 AU. Data were acquired during a nearly 2 week period in May-June 1997 at a latitude of 9-10 degrees north of the equator, on the east limb and, hence, in the streamer belt and the source location of slow wind. Density and outflow speed are compared, in order to check for preservation of the near Sun characteristics in the interplanetary medium. By chance, Ulysses was at the very northern edge of the visible streamer belt. Nevertheless, no evidence of fast wind, or mixing with fast wind coming from the northern polar coronal hole, was evident at Ulysses. The morphology of the streamer belt was similar at the beginning and end of the observation period, but was markedly different during the middle of the period. A corresponding change in density (but not flow speed) was noted at Ulysses.

  6. Lipase catalyzed esterification of glycidol in nonaqueous solvents: solvent effects on enzymatic activity.

    PubMed

    Martins, J F; de Sampaio, T C; de Carvalho, I B; Barreiros, S

    1994-06-01

    We studied the effect of organic solvents on the kinetics of porcine pancreatic lipase (pp) for the resolution of racemic glycidol through esterification with butyric acid. We quantified ppl hydration by measuring water sorption isotherms for the enzyme in the solvents/mixtures tested. The determination of initial rates as a function of enzyme hydration revealed that the enzyme exhibits maximum apparent activity in the solvents/mixtures at the same water content (9% to 11% w/w) within the associated experimental error. The maximum initial rates are different in all the media and correlate well with the logarithm of the molar solubility of water in the media, higher initial rates being observed in the solvents/mixtures with lower water solubilities. The data for the mixtures indicate that ppl apparent activity responds to bulk property of the solvent. Measurements of enzyme particle sizes in five of the solvents, as function of enzyme hydration, revealed that mean particle sizes increased with enzyme hydration in all the solvents, differences between solvents being more pronounced at enzyme hydration levels close to 10%. At this hydration level, solvents having a higher water content lead to lower reaction rates; these are the solvents where the mean enzyme particle sizes are greater. Calculation of the observable modulus indicates there are no internal diffusion limitations. The observed correlation between changes in initial rates and changes in external surface area of the enzyme particles suggests that interfacial activation of ppl is only effective at the external surface of the particles. Data obtained for the mixtures indicate that ppl enantioselectivity depends on specific solvent-enzyme interactions. We make reference to ppl hydration and activity in supercritical carbon dioxide.

  7. A simple approach to the solvent reorganization Gibbs free energy in electron transfer reactions of redox metalloproteins

    NASA Astrophysics Data System (ADS)

    Kharkats, Yurij I.; Ulstrup, Jens

    1999-04-01

    We discuss a simple model for the environmental reorganisation Gibbs free energy, Er, in electron transfer between a metalloprotein and a small reaction partner. The protein is represented as a dielectric globule with low dielectric constant, the metal centres as conducting spheres, all embedded in a continuous solvent with high dielectric constant. This model has previously reproduced thermodynamic metalloprotein properties. Er takes an analytic form expressed by a continuous image charge distribution, and depends weakly on the globular radius, indicating that repolarisation at the globule/solvent interface contributes less to these effects than to the work terms and driving force.

  8. Vapochromic luminescence and flexibility control of porous coordination polymers by substitution of luminescent multinuclear Cu(I) cluster nodes.

    PubMed

    Hayashi, Takahiro; Kobayashi, Atsushi; Ohara, Hiroki; Yoshida, Masaki; Matsumoto, Takeshi; Chang, Ho-Chol; Kato, Masako

    2015-09-21

    Two luminescent porous coordination polymers (PCPs), i.e., [Cu2(μ2-I)2ctpyz]n and [Cu4(μ3-I)4ctpyz]n (Cu2 and Cu4, respectively; ctpyz = cis-1,3,5-cyclohexanetriyl-2,2',2″-tripyrazine), were successfully synthesized and characterized by single-crystal X-ray diffraction and luminescence spectroscopic measurements. Cu2 consists of rhombus-type dinuclear {Cu2I2} cores bridged by ctpyz ligands, while Cu4 is constructed of cubane-type tetranuclear {Cu4I4} cores bridged by ctpyz ligands. The void fraction of Cu4 is estimated to be 48.0%, which is significantly larger than that of Cu2 (19.9%). Under UV irradiation, both PCPs exhibit red luminescence at room temperature in the solid state (λem values of 660 and 614 nm for Cu2 and Cu4, respectively). Although the phosphorescence of Cu2 does not change upon removal and/or adsorption of EtOH solvent molecules in the porous channels, the solid-state emission maximum of Cu4 red-shifts by 36 nm (λem = 650 nm) upon the removal of the adsorbed benzonitrile (PhCN) molecules from the porous channels (and vice versa). This large difference in the vapochromic behavior of Cu2 and Cu4 is closely related to the framework flexibility. The framework of Cu2 is sufficiently rigid to retain the porous structure without solvated EtOH molecules, whereas the porous structure of Cu4 collapses easily after removal of the adsorbed PhCN molecules to form a nonporous amorphous phase. The original vapor-adsorbed porous structure of Cu4 is regenerated by exposure of the amorphous solid to not only PhCN vapor but also tetrahydrofuran, acetone, ethyl acetate, and N,N-dimethylformamide vapors. The Cu4 structures with the various adsorbed solvents showed almost the same emission maxima as the original PhCN-adsorbed Cu4, except for DMF-adsorbed Cu4, which showed no luminescence probably because of weak coordination of the DMF vapor molecules to the Cu(I) centers of the tetranuclear {Cu4I4} core.

  9. Scale-up of recovery process for waste solvents

    NASA Astrophysics Data System (ADS)

    Bohnert, G. W.; Carey, D. A.

    1991-02-01

    Recycling of spent cleaning solvents, 1,1,1 trichloroethane, trichloroethylene, and trichlorotrifluoroethane at KCP was evaluated. Gas chromatography was used to identify stabilization levels in virgin and recycled solvent. Segregation, pretreatment, and distillation processes were defined. Existing distillation equipment was modified and a solvent drying process was added. Recycled solvent quality of several production lots is also presented.

  10. Scale-up of recovery process for waste solvents

    SciTech Connect

    Bohnert, G.W.; Carey, D.A.

    1991-02-01

    Recycling of spent cleaning solvents, 1,1,1 trichloroethane, trichloroethylene, and trichlorotrifluoroethane at KCP was evaluated. Gas chromatography was used to identify stabilization levels in virgin and recycled solvent. Segregation, pretreatment and distillation processes were defined. Existing distillation equipment was modified and a solvent drying process was added. Recycled solvent quality of several production lots is also presented. 3 figs., 4 tabs.

  11. Solvent disperser for removing oil from sponge core

    SciTech Connect

    Di Foggio, R.

    1988-09-20

    This patent describes method for dispersing solvent for use in determining the oil saturation of an earth formation by means of sponge coring, comprising: (a) receiving solvent dripping downwardly, and (b) conducting the received solvent by means of capillary action to an application zone located and dimensioned for passing such solvent to the sponge in a sponge core barrel.

  12. Coordinated Transportation: Problems and Promise?

    ERIC Educational Resources Information Center

    Fickes, Michael

    1998-01-01

    Examines the legal, administrative, and logistical barriers that have prevented the wide acceptance of coordinating community and school transportation services and why these barriers may be breaking down. Two examples of successful implementation of coordinated transportation are examined: employing a single system to serve all transportation…

  13. The K-12 Technology Coordinator

    ERIC Educational Resources Information Center

    Lesisko, Lee James

    2005-01-01

    The Pennsylvania Department of Education requires Technology Coordinators employed by public school districts in the Commonwealth to be properly certified. The Technology Coordinator is responsible to implement instructional technology for the district, provide leadership in the use of technological delivery systems, and routinely work directly…

  14. Drift Hamiltonian in magnetic coordinates

    SciTech Connect

    White, R.B.; Boozer, A.H.; Hay, R.

    1982-02-01

    A Hamiltonian formulation of the guiding-center drift in arbitrary, steady state, magnetic and electric fields is given. The canonical variables of this formulation are simply related to the magnetic coordinates. The modifications required to treat ergodic magnetic fields using magnetic coordinates are explicitly given in the Hamiltonian formulation.

  15. Newtonian and relativistic emission coordinates

    SciTech Connect

    Coll, Bartolome; Ferrando, Joan Josep; Morales-Lladosa, Juan Antonio

    2009-09-15

    Emission coordinates are those generated by positioning systems. Positioning systems are physical systems constituted by four emitters broadcasting their respective times by means of sound or light signals. We analyze the incidence of the space-time causal structure on the construction of emission coordinates. The Newtonian case of four emitters at rest is analyzed and contrasted with the corresponding situation in special relativity.

  16. What Happened to Service Coordination?

    ERIC Educational Resources Information Center

    McWilliam, R. A.

    2006-01-01

    Comments on an article by Dunst and Bruder. Service coordination was supposed to be one of the major jewels in the legislative crown for young children with disabilities and their families. The authors have cast their experienced eyes on the heart of the matter, which is the models of service coordination that sprang to life almost immediately…

  17. Coordination challenges for autonomous spacecraft

    NASA Technical Reports Server (NTRS)

    Clement, B. J.; Barrett, A.

    2002-01-01

    While past flight projects involved a single spacecraft in isolation, over forty proposed future missions involve multiple coordinated spacecraft. This paper presents characteristics of such missions in terms of properties of the phenomena being measured as well as the rationale for using multiple spacecraft. We describe the coordination problems associated with operating these missions and identify needed technologies.

  18. Hazardous solvents: Innovative alternatives offer choices

    SciTech Connect

    Melody, M.

    1993-01-01

    Use of hazardous solvents pose various problems for industry, including contributing to depletion of the stratospheric ozone layer, creating hazardous wastes and exposing workers to dangerous chemicals. Several environmental laws regulate the use of hazardous solvents, but only mandated phaseouts have prompted action by businesses. The CAA Amendments and the Montreal Protocol on Substances That Deplete the Ozone Layer are generating industry response, because they order the phaseout of two popular solvents -- CFCs and 1,1,1-trichloroethane. Regulations and hazardous waste disposal costs are the major factors influencing companies to switch to alternative cleaning solvents and technologies. Another factor contributing to the demand for alternative cleaners and processes is increased awareness of risks associated with hazardous solvents. Although most alternative cleaners do not have hazardous characteristics, the contaminants they remove may be hazardous. Vendors, therefore, are cautious about discussing waste disposal. Many facilities switching to aqueous and semi-aqueous systems need to install or modify wastewater treatment facilities, add a filtration system to recycle water, or buy water evaporators.

  19. Non-aqueous cleaning solvent substitution

    NASA Technical Reports Server (NTRS)

    Meier, Gerald J.

    1994-01-01

    A variety of environmental, safety, and health concerns exist over use of chlorinated and fluorinated cleaning solvents. Sandia National Laboratories, Lawrence Livermore National Laboratories, and the Kansas City Division of AlliedSignal have combined efforts to focus on finding alternative cleaning solvents and processes which are effective, environmentally safe, and compliant with local, state, and federal regulations. An alternative solvent has been identified, qualified, and implemented into production of complex electronic assemblies, where aqueous and semi-aqueous cleaning processes are not allowed. Extensive compatibility studies were performed with components, piece-parts, and materials. Electrical testing and accelerated aging were used to screen for detrimental, long-term effects. A terpene, d-limonene, was selected as the solvent of choice, and it was found to be compatible with the components and materials tested. A brief history of the overall project will be presented, along with representative cleaning efficiency results, compatibility results, and residual solvent data. The electronics industry is constantly searching for proven methods and environmentally-safe materials to use in manufacturing processes. The information in this presentation will provide another option to consider on future projects for applications requiring high levels of quality, reliability, and cleanliness from non-aqueous cleaning processes.

  20. Non-aqueous cleaning solvent substitution

    SciTech Connect

    Meier, G.J.

    1994-01-01

    A variety of environmental, safety, and health concerns exist over use of chlorinated and fluorinated cleaning solvents. Sandia National Laboratories, Lawrence Livermore National Laboratories, and the Kansas City Division of Allied Signal have combined efforts to focus on finding alternative cleaning solvents and processes which are effective, environmentally safe, and compliant with local, state, and federal regulations. An alternative solvent has been identified, qualified, and implemented into production of complex electronic assemblies, where aqueous and semi-aqueous cleaning processes are not allowed. Extensive compatibility studies were performed with components, piece-parts, and materials. Electrical testing and accelerated aging were used to screen for detrimental, long-term effects. A terpene, d-limonene, has been selected as the solvent of choice, and has been found to be compatible with the components and materials tested. A brief history of the overall project will be presented, along with representative cleaning efficiency results, compatibility results, and residual solvent data. The electronics industry is constantly searching for proven methods and environmentally safe materials to use in manufacturing processes. The information in this presentation will provide another option to consider on future projects for applications requiring high levels of quality, reliability, and cleanliness from non-aqueous cleaning processes.

  1. Solvent gating of intramolecular electron transfer

    SciTech Connect

    Miller, R.M. ); Spears, K.G.; Gong, J.H.; Wach, M. )

    1994-02-03

    The rates for ionic photodissociation of malachite green leucocyanide to form cyanide ion and a malachite green carbonium ion were measured as a function of solvent and temperature. The observed rates in mixtures of polar and nonpolar solvents all had an activation energy of about 1 kcal/mol for a wide range of dielectric constants. This dissociative intramolecular electron transfer (DIET) is unusual because it is the first example where solvent configurational entropy changes are required to enable a large amplitude molecular distortion leading to a nonadiabatic electron transfer and ionic dissociation. This solvent gated intramolecular electron-transfer mechanism is supported by analysis of the preexponential and activation energy trends in dipolar aprotic solven mixtures and alcohol solvents. The large amplitude motion is not separately measurable due to the slow gating rates, but viscosity effects on both the preexponential and the activation energy are analyzed to demonstrate consistency with a barrierless diffusion model having a structural dependence on electron-transfer rate. The rate has an inverse dependence on viscosity raised to the 0.53 power. 36 refs., 6 figs., 4 tabs.

  2. Solvent extraction of phenols from water

    SciTech Connect

    Greminger, D.C.; Burns, G.P.; Lynn, S.; Hanson, D.H.; King, C.J.

    1980-02-01

    Methyl isobutyl ketone (MIBK) and diisopropyl ether (DIPE) have been evaluated as solvents for extraction of phenols, at high dilution, from water. Equilibrium distribution coefficients (K/sub D/) have been measured for phenol, dihydroxybenzenes and trihydroxybenzenes in both solvents as a function of pH. Particularly for the multihydric phenols, MIBK gives substantially higher values of K/sub D/ than does DIPE. The effect of pH can be described quantitatively through a simple ionization model, using published values of dissociation constants for the various phenols. Some method for removal of residual dissolved solvent must ordinarily be included in any extraction process for phenols. Possibilities include atmospheric-steam or inert-gas stripping, vacuum-steam stripping, and extraction with a second solvent. Vacuum-steam stripping is a particularly attractive choice for removal of MIBK; this reinforces the utility of MIBK as a solvent. The optimal temperature for vacuum stripping is generally the temperature of the extraction operation, which in turn is related to the effect of temperature on K/sub D/. Values of K/sub D/ for phenol-water-MIBK were determined at 30, 50, and 75/sup 0/C, and were found to decrease with increasing temperature at all concentrations.

  3. Towards ultra-fast solvent evaporation, the development of a computer controlled solvent vapor annealing chamber

    NASA Astrophysics Data System (ADS)

    Nelson, Gunnar; Wong, J.; Drapes, C.; Grant, M.; Baruth, A.

    Despite the promise of cheap and fast nanoscale ordering of block polymer thin films via solvent vapor annealing, a standardized, scalable production scheme remains elusive. Solvent vapor annealing exposes a nano-thin film to the vapors of one or more solvents with the goal of forming a swollen and mobile state to direct the self-assembly process by tuning surface energies and mediating unfavorable chain interactions. We have shown that optimized annealing conditions, where kinetic and thermal properties for crystal growth are extremely fast (<1s), exist at solvent concentrations just below the order-disorder transition of the film. However, when investigating the propagation of a given morphology into the bulk of a film during drying, the role of solvent evaporation comes under great scrutiny. During this process, the film undergoes a competition between two fronts; phase separation and kinetic trapping. Recent results in both theory and experiment point toward this critical element in controlling the resultant morphologies; however, no current method includes a controllable solvent evaporation rate at ultra-fast time scales. We report on a computer-controlled, pneumatically actuated chamber that provides control over solvent evaporation down to 15 ms. Furthermore, in situ spectral reflectance monitors solvent concentration with 10 ms temporal resolution and reveals several possible evaporation trajectories, ranging from linear to exponential to logarithmic. Funded by Dr. Randolph Ferlic Summer Research Scholarship and NASA Nebraska Space Grant.

  4. Changes in psychological performances of solvent-poisoned and solvent-exposed workers

    SciTech Connect

    Lindstroem, K.

    1980-01-01

    The changes in psychological performances associated with long-term exposure to organic solvents and solvent mixtures were studied in a group of 56 male workers diagnosed as having an occupational disease caused by solvents. Their mean duration of exposure was 9.1 +/- SD 8.3 years, and they were exposed mainly to halogenated and aromatic hydrocarbons and to mixtures of paint solvents. The psychological performances of these solvent-exposed patients were compared with those of 98 styrene-exposed workers and a nonexposed group of 43 construction workers. The applied psychological test variables were factor analyzed, before other statistical analysis, in order to clarify what they measured in the present study. The solvent-exposed group was characterized by a decline in visuomotor performance and decreased freedom from distractibility. The poor visuomotor performances were also related to the long duration of solvent exposure in this group of patients. The index applied for the exposure level revealed no significant relationships to psychological performances among the solvent-exposed patients. The psychological performances of the styrene-exposed group differed only very slightly from those of the nonexposed workers.

  5. Hadronic Weak Interaction Studies at the SNS

    NASA Astrophysics Data System (ADS)

    Fomin, Nadia

    2016-03-01

    Neutrons have been a useful probe in many fields of science, as well as an important physical system for study in themselves. Modern neutron sources provide extraordinary opportunities to study a wide variety of physics topics. Among them is a detailed study of the weak interaction. An overview of studies of the hadronic weak (quark-quark) as well as semi-leptonic (quark-lepton) interactions at the Spallation Neutron Source (SNS) is presented. These measurements, done in few-nucleon systems, are finally letting us gain knowledge of the hadronic weak interaction without the contributions from nuclear effects. Forthcoming results from the NPDGamma experiment will, due to the simplicity of the neutron, provide an unambiguous measurement of the long range pion-nucleon weak coupling (often referred to as hπ), which will finally test the theoretical predictions. Results from NPDGamma and future results from the n +3 He experiment will need to be complemented by additional measurements to completely describe the hadronic weak interaction.

  6. Experimental noiseless linear amplification using weak measurements

    NASA Astrophysics Data System (ADS)

    Ho, Joseph; Boston, Allen; Palsson, Matthew; Pryde, Geoff

    2016-09-01

    The viability of quantum communication schemes rely on sending quantum states of light over long distances. However, transmission loss can degrade the signal strength, adding noise. Heralded noiseless amplification of a quantum signal can provide a solution by enabling longer direct transmission distances and by enabling entanglement distillation. The central idea of heralded noiseless amplification—a conditional modification of the probability distribution over photon number of an optical quantum state—is suggestive of a parallel with weak measurement: in a weak measurement, learning partial information about an observable leads to a conditional back-action of a commensurate size. Here we experimentally investigate the application of weak, or variable-strength, measurements to the task of heralded amplification, by using a quantum logic gate to weakly couple a small single-optical-mode quantum state (the signal) to an ancilla photon (the meter). The weak measurement is carried out by choosing the measurement basis of the meter photon and, by conditioning on the meter outcomes, the signal is amplified. We characterise the gain of the amplifier as a function of the measurement strength, and use interferometric methods to show that the operation preserves the coherence of the signal.

  7. Explaining numeracy development in weak performing kindergartners.

    PubMed

    Toll, Sylke W M; Van Luit, Johannes E H

    2014-08-01

    Gaining better insight into precursors of early numeracy in young children is important, especially in those with inadequate numeracy skills. Therefore, in the current study, visual and verbal working memory, non-symbolic and symbolic comparison skills, and specific math-related language were used to explain early numeracy performance and development of weak performing children throughout kindergarten. The early numeracy ability of both weak performers and typical performers was measured at four time points during 2 years of kindergarten to compare growth rates. Results show a significant faster development of early numeracy in the weak performers. The development of weak performers' numeracy was influenced by verbal working memory, symbolic comparison skills, and math language, whereas only math language was positively related to the slope of typical performers' numeracy. In the weak performers, visual working memory, non-symbolic comparison skills, and math language showed an effect on the initial early numeracy level of these children. The intercept of the typical performers was predicted by five covariates, all except non-symbolic comparison. PMID:24786672

  8. DRAM Weak Cell Characterization for Retention Time.

    PubMed

    Kang, Jonghyuk; Lee, Sungho; Choi, Byoungdeog

    2016-05-01

    This work proposes a sequence of tests for detecting refresh weak cells based on data retention time distribution in the main cell array of DRAMs and verify the feasibility of the proposed method through analysis of 30 nm design-rule DRAM cells with Recess Channel Array Transistor (RCAT) and Buried Channel Array Transistor (BCAT). Basic idea of the proposed mechanism is to test with different bias conditions and break down retention failures based on their root causes such as Gate Induced Drain Leakage, sub-threshold leakage and junction leakage. This categorization helps to determine the physical locations of each failure group, enabling precise Physical Failure Analysis (PFA). The characterization of data retention weak cells for 30 nm design rule DRAMs with BCAT and RCAT has been investigated. Most weak cells were classified as GIDL leaky cells in both cases. In the case of BCAT, the distance between the word line and the storage node, caused by the process distribution, is the main origin of weak cells. In the case of RCAT, the sharp corner of the active layer in the storage node is the main cause of weak cells. PMID:27483878

  9. Archimedes' principle in general coordinates

    NASA Astrophysics Data System (ADS)

    Ridgely, Charles T.

    2010-05-01

    Archimedes' principle is well known to state that a body submerged in a fluid is buoyed up by a force equal to the weight of the fluid displaced by the body. Herein, Archimedes' principle is derived from first principles by using conservation of the stress-energy-momentum tensor in general coordinates. The resulting expression for the force is applied in Schwarzschild coordinates and in rotating coordinates. Using Schwarzschild coordinates for the case of a spherical mass suspended within a perfect fluid leads to the familiar expression of Archimedes' principle. Using rotating coordinates produces an expression for a centrifugal buoyancy force that agrees with accepted theory. It is then argued that Archimedes' principle ought to be applicable to non-gravitational phenomena, as well. Conservation of the energy-momentum tensor is then applied to electromagnetic phenomena. It is shown that a charged body submerged in a charged medium experiences a buoyancy force in accordance with an electromagnetic analogue of Archimedes' principle.

  10. Chlorinated solvent replacements recycle/recovery review report

    SciTech Connect

    Beal, M.; Hsu, D.; McAtee, R.E.; Weidner, J.R.; Berg, L.; McCandless, F.P.; Waltari, S.; Peterson, C.

    1992-08-01

    This report is a literature review of waste solvents recycle/recovery methods and shows the results of solvent separations using membrane and distillation technologies. The experimental solvent recovery methods were conducted on solvent replacements for chlorinated solvents at Montana State University. The literature review covers waste solvents separation using distillation, membranes decantation, filtration, carbon adsorption, solvent extraction, and other vapor-phase separation techniques. The results of this study identify solvent distillation methods as the most common separation technique. The alternative separation methods typically supplement distillation. The study shows the need for industries to identify waste solvent disposal methods and investigate the economics of waste solvent recycling as a possible waste reduction method.

  11. Development of deep eutectic solvents applied in extraction and separation.

    PubMed

    Li, Xiaoxia; Row, Kyung Ho

    2016-09-01

    Deep eutectic solvents, as an alternative to ionic liquids, have greener credentials than ionic liquids, and have attracted considerable attention in related chemical research. Deep eutectic solvents have attracted increasing attention in chemistry for the extraction and separation of various target compounds from natural products. This review highlights the preparation of deep eutectic solvents, unique properties of deep eutectic solvents, and synthesis of deep-eutectic-solvent-based materials. On the other hand, application in the extraction and separation of deep eutectic solvents is also included in this report. In this paper, the available data and references in this field are reviewed to summarize the applications and developments of deep eutectic solvents. Based on the development of deep eutectic solvents, an exploitation of new deep eutectic solvents and deep eutectic solvents-based materials is expected to diversify into extraction and separation.

  12. A protein molecule in an aqueous mixed solvent: fluctuation theory outlook.

    PubMed

    Shulgin, Ivan L; Ruckenstein, Eli

    2005-08-01

    In the present paper a procedure to calculate the properties of proteins in aqueous mixed solvents, particularly the excesses of the constituents of the mixed solvent near the protein molecule and the preferential binding parameters, is suggested. Expressions for the Kirkwood-Buff integrals in ternary mixtures and for the preferential binding parameter were derived and used to calculate various properties of infinitely dilute proteins in aqueous mixed solvents. The derived expressions and experimental information regarding the partial molar volumes and the preferential binding parameters were used to calculate the excesses (deficits) of water and cosolvent (in comparison with the bulk concentrations of protein-free mixed solvent) in the vicinity of ribonuclease A, ribonuclease T1, and lysozyme molecules. The calculations showed that water was in excess in the vicinity of ribonuclease A for water/glycerol and water/trehalose mixtures, and the cosolvent urea was in excess in the vicinity of ribonuclease T1 and lysozyme. The derivative of the activity coefficient of the protein with respect to the mole fraction of water was also calculated. This derivative was negative for the water/glycerol and water/trehalose mixed solvents and positive for the water/urea mixture. The mixture of lysozyme in the water/urea solvent is of particular interest, because the lysozyme at pH 7.0 is in its native state up to 9.3M urea, while at pH 2.0 it is denaturated between 2.5 and 5M and higher concentrations of urea. Our results demonstrated a striking similarity in the hydration of lysozyme at both pHs. It is worthwhile to note that the excesses of urea were only weakly composition dependent on both cases.

  13. Towards safer sodium-ion batteries via organic solvent/ionic liquid based hybrid electrolytes

    NASA Astrophysics Data System (ADS)

    Monti, Damien; Ponrouch, Alexandre; Palacín, M. Rosa; Johansson, Patrik

    2016-08-01

    Hybrid electrolytes aimed at application in sodium-ion batteries (SIB) consisting of an organic solvent mixture (EC:PC) and different ionic liquids (ILs); EMImTFSI, BMImTFSI, and Pyr13TFSI, and with the NaTFSI salt providing the Na+ charge carriers have here been extensively studied. The physico-chemical and electrochemical characterisation includes ionic conductivity, viscosity, density, cation coordination and solvation, various safety measures, and electrochemical stability window (ESW). Hybrid electrolytes with 10-50% of IL content were found to have ionic conductivities on par with comparable organic solvent based electrolytes, but with highly enhanced safety properties. A systematic Raman spectroscopy study of the cation coordination and solvation before and after electrolyte safety tests by ignition suggest that IL cations and TFSI remain stable when ignited while organic solvents are consumed. Finally, the solid electrolyte interphase (SEI) formed when using hybrid electrolytes has both better mechanical and electrochemical stability than the SEI derived from pure IL based electrolytes. For a half-cell with a hard carbon (HC) electrode and a hybrid electrolyte with a composition of 0.8 m NaTFSI in EC0.45:PC0.45:Pyr13TFSI0.10 encouraging results were obtained for IL based electrolytes - ca. 182 mAhg-1 at C/10 over 40 cycles.

  14. Towards safer sodium-ion batteries via organic solvent/ionic liquid based hybrid electrolytes

    NASA Astrophysics Data System (ADS)

    Monti, Damien; Ponrouch, Alexandre; Palacín, M. Rosa; Johansson, Patrik

    2016-08-01

    Hybrid electrolytes aimed at application in sodium-ion batteries (SIB) consisting of an organic solvent mixture (EC:PC) and different ionic liquids (ILs); EMImTFSI, BMImTFSI, and Pyr13TFSI, and with the NaTFSI salt providing the Na+ charge carriers have here been extensively studied. The physico-chemical and electrochemical characterisation includes ionic conductivity, viscosity, density, cation coordination and solvation, various safety measures, and electrochemical stability window (ESW). Hybrid electrolytes with 10-50% of IL content were found to have ionic conductivities on par with comparable organic solvent based electrolytes, but with highly enhanced safety properties. A systematic Raman spectroscopy study of the cation coordination and solvation before and after electrolyte safety tests by ignition suggest that IL cations and TFSI remain stable when ignited while organic solvents are consumed. Finally, the solid electrolyte interphase (SEI) formed when using hybrid electrolytes has both better mechanical and electrochemical stability than the SEI derived from pure IL based electrolytes. For a half-cell with a hard carbon (HC) electrode and a hybrid electrolyte with a composition of 0.8 m NaTFSI in EC0.45:PC0.45:Pyr13TFSI0.10 encouraging results were obtained for IL based electrolytes - ca. 182 mAhg-1 at C/10 over 40 cycles.

  15. Solvent effects on chemical processes. 8. Demethylation kinetics of aspartame in binary aqueous-organic solvents.

    PubMed

    Skwierczynski, R D; Connors, K A

    1994-12-01

    The kinetics of demethylation of aspartame were studied in binary aqueous-organic solvent mixtures at 25 degrees C under two solution conditions, namely 1.0 M HCl (pH 0.28 in water) and carbonate buffer (pH 10.1 in water). Under these conditions solvent effects on the acid dissociation constants of aspartame do not complicate the interpretation of the kinetics. The organic cosolvents were acetone, acetonitrile, dimethyl sulfoxide, dioxane, tetrahydrofuran, and methanol. The observed kinetic solvent effects were modest in magnitude, not exceeding a factor of 3 in rate constant, relative to the fully aqueous solution. The rate changes included both increases and decreases, and in some solvent mixtures extrema were observed. It is concluded that at least two contributory factors, identified as an electrostatic (dielectric constant) effect and a solvation effect, must be operating to produce the observed kinetic solvent effects.

  16. Ion Exchange and Solvent Extraction: Supramolecular Aspects of Solvent Exchange Volume 21

    SciTech Connect

    Gloe, Karsten; Tasker, Peter A; Oshima, Tatsuya; Watarai, Hitoshi; Nilsson, Mikael

    2013-01-01

    Preface The theme of supramolecular chemistry (SC), entailing the organization of multiple species through noncovalent interactions, has permeated virtually all aspects of chemical endeavor over the past several decades. Given that the observed behavior of discrete molecular species depends upon their weak interactions with one another and with matrix components, one would have to conclude that SC must indeed form part of the fabric of chemistry itself. A vast literature now serves to categorize SC phenomena within a body of consistent terminology. The word supramolecular itself appears in the titles of dozens of books, several journals, and a dedicated encyclopedia. Not surprisingly, the theme of SC also permeates the field of solvent extraction (SX), inspiring the framework for this volume of Ion Exchange and Solvent Extraction. It is attempted in the six chapters of this volume to identify both how supramolecular behavior occurs and is studied in the context of SX and how SC is influencing the current direction of SX. Researchers and practitioners have long dealt with supramolecular interactions in SX. Indeed, the use of polar extractant molecules in nonpolar media virtually assures that aggregative interactions will dominate the solution behavior of SX. Analytical chemists working in the 1930s to the 1950s with simple mono- and bidentate chelating ligands as extractants noted that extraction of metal ions obeyed complicated mass-action equilibria involving complex stoichiometries. As chemists and engineers developed processes for nuclear and hydrometallurgical applications in the 1950s and 1960s, the preference for aliphatic diluents only enhanced the complexity and supramolecular nature of extraction chemistry. Use of physical techniques such as light scattering and vapor-pressure measurements together with various spectroscopic methods revealed organic-phase aggregates from well-defined dimers to small aggregates containing a few extractant molecules to large

  17. 40 CFR Table 3 to Subpart Nnnn of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 13 2013-07-01 2012-07-01 true Default Organic HAP Mass Fraction for...—Default Organic HAP Mass Fraction for Solvents and Solvent Blends You may use the mass fraction values in... formulation data. Solvent/solvent blend CAS. No. Average organic HAP mass fraction Typical organic...

  18. 40 CFR Table 6 to Subpart Kkkk of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 13 2014-07-01 2014-07-01 false Default Organic HAP Mass Fraction for... Organic HAP Mass Fraction for Solvents and Solvent Blends You may use the mass fraction values in the.... Solvent/solvent blend CAS. No. Averageorganic HAP mass fraction Typical organic HAP, percent by mass...

  19. 40 CFR Table 4 to Subpart Oooo of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 12 2011-07-01 2009-07-01 true Default Organic HAP Mass Fraction for... 63—Default Organic HAP Mass Fraction for Solvents and Solvent Blends You may use the mass fraction... formulation data. Solvent/solvent blend CAS. No. Averageorganic HAP mass fraction Typical organic HAP,...

  20. 40 CFR Table 3 to Subpart Rrrr of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 13 2012-07-01 2012-07-01 false Default Organic HAP Mass Fraction for... Organic HAP Mass Fraction for Solvents and Solvent Blends You may use the mass fraction values in the...: Solvent/Solvent blend CAS. No. Average organic HAP mass fraction Typical organic HAP, percent by mass...