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1

Silver(I) complexes of the weakly coordinating solvents SO(2) and CH(2)Cl(2): crystal structures, bonding, and energetics of [Ag(OSO)][Al{OC(CF(3))(3)}(4)], [Ag(OSO)(2/2)][SbF(6)], and [Ag(CH(2)Cl(2))(2)][SbF(6)].  

PubMed

Pushing the limits of coordination chemistry: The most weakly coordinated silver complexes of the very weakly coordinating solvents dichloromethane and liquid sulfur dioxide were prepared. Special techniques at low temperatures and the use of weakly coordinating anions allowed structural characterization of [Ag(OSO)][Al{OC(CF(3))(3)}(4)], [Ag(OSO)(2/2)][SbF(6)], and [Ag(Cl(2)CH(2))(2)][SbF(6)] (see figure). An investigation of the bonding shows that these complexes are mainly stabilized by electrostatic monopole-dipole interactions.The synthetically useful solvent-free silver(I) salt Ag[Al(pftb)(4)] (pftb=--OC(CF(3))(3)) was prepared by metathesis reaction of Li[Al(pftb)(4)] with Ag[SbF(6)] in liquid SO(2). The solvated complexes [Ag(OSO)][Al(pftb)(4)], [Ag(OSO)(2/2)][SbF(6)], and [Ag(CH(2)Cl(2))(2)][SbF(6)] were prepared and isolated by special techniques at low temperatures and structurally characterized by single-crystal X-ray diffraction. The SO(2) complexes provide the first examples of coordination of the very weak Lewis base SO(2) to silver(I). The SO(2) molecule in [Ag(OSO)][Al(pftb)(4)] is eta(1)-O coordinated to Ag(+), while the SO(2) ligands in [Ag(OSO)(2/2)][SbF(6)] bridge two Ag(+) ions in an eta(2)-O,O' (trans,trans) manner. [Ag(CH(2)Cl(2))(2)][SbF(6)] contains [Ag(CH(2)Cl(2))(2)](+) ions linked through [SbF(6)](-) ions to give a polymeric structure. The solid-state silver(I) ion affinities (SIA) of SO(2) and CH(2)Cl(2), based on bond lengths and corresponding valence units in the corresponding complexes and tensimetric titrations of Ag[Al(pftb)(4)] and Ag[SbF(6)] with SO(2) vapor, show that SO(2) is a weaker ligand to Ag(+) than the commonly used weakly coordinating solvent CH(2)Cl(2) and indicated that binding strength of SO(2) to silver(I) in the silver(I) salts increases with increasing size of the corresponding counteranion ([Al(pftb)(4)](-)>[SbF(6)](-)). The experimental findings are in good agreement with theoretical gas-phase ligand-binding energies of [Ag(L)(n)](+) (L=SO(2), CH(2)Cl(2); n=1, 2) and solid-state enthalpies obtained from Born-Fajans-Haber cycles by using the volume-based thermodynamics (VBT) approach. Bonding analysis (VB, NBO, MO) of [Ag(L)(n)](+) suggests that these complexes are almost completely stabilized by electrostatic interaction, that is, monopole-dipole interaction, with almost no covalent contribution by electron donation from the ligand orbitals into the vacant 5s orbital of Ag(+). All experimental findings and theoretical considerations demonstrate that SO(2) is less covalently bound to Ag(+) than CH(2)Cl(2) and support the thesis that SO(2) is a polar but non-coordinating solvent towards Ag(+). PMID:19449357

Decken, Andreas; Knapp, Carsten; Nikiforov, Grigori B; Passmore, Jack; Rautiainen, J Mikko; Wang, Xinping; Zeng, Xiaoqing

2009-06-22

2

Solvent extraction: the coordination chemistry behind extractive metallurgy.  

PubMed

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. PMID:24088789

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

2014-01-01

3

Molecular dynamics study of the weakly solvent dependent relaxation dynamics following chlorine dioxide photoexcitation  

E-print Network

Molecular dynamics study of the weakly solvent dependent relaxation dynamics following chlorine The solvation dynamics following photoexcitation of chlorine dioxide OClO in different solvents are investigated chemistry.1­3 Representative of this group of compounds, chlorine dioxide OClO has been the subject of much

4

Bimodal dielectric relaxation of electrolyte solutions in weakly polar solvents  

NASA Astrophysics Data System (ADS)

The dielectric relaxation spectra of dilute electrolyte solutions in solvents of small dielectric constants are investigated both theoretically and experimentally. The theoretical calculation in our previous work [T. Yamaguchi, T. Matsuoka, and S. Koda, J. Chem. Phys. 135, 164511 (2011)] is reanalyzed, and it is shown that the dielectric relaxation spectra are composed of three components, namely, the relaxation of ionic atmosphere, the reorientational relaxation of ion pairs, and the collision between ions. The relaxation frequency of the slowest one increases with increasing the concentration, and the slower two relaxations, those of ionic atmosphere and ion pairs, merge into one at the concentration where the Debye length is comparable to the size of ions. Experimentally, the dielectric relaxation spectra of some electrolytes in two solvents, tetrahydrofuran and tetraglyme, are determined at frequencies from 300 kHz to 200 MHz, and the presence of the slower two relaxations was confirmed. The concentration dependence of the relaxation frequency is also in harmony with the theoretical calculation. The relationship between the dielectric relaxation spectra and the concentration dependence of the ionic conductivity is discussed.

Yamaguchi, Tsuyoshi; Koda, Shinobu

2014-12-01

5

Coordinative Properties of Highly Fluorinated Solvents with Amino and Ether Groups  

PubMed Central

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

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

2008-01-01

6

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

PubMed

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-p?-P-d? 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. PMID:25312248

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

2014-12-01

7

NMR crystallography for structural characterization of oxovanadium(v) complexes: deriving coordination geometry and detecting weakly coordinated ligands at atomic resolution in the solid state.  

PubMed

NMR crystallography is an emerging method for atomic-resolution structural analysis of ubiquitous vanadium(V) sites in inorganic and bioinorganic complexes as well as vanadium-containing proteins. NMR crystallography allows for characterization of vanadium(V) containing solids, based on the simultaneous measurement of (51)V-(15)N internuclear distances and anisotropic spin interactions, described by (13)C, (15)N, and (51)V chemical shift anisotropy and (51)V electric field gradient tensors. We show that the experimental (51)V, (13)C, and (15)N NMR parameters are essential for inferring correct coordination numbers and deriving correct geometries in density functional theory (DFT) calculations, particularly in the absence of single-crystal X-ray structures. We first validate this approach on a structurally known vanadium(V) complex, ((15)N-salicylideneglycinate)-(benzhydroxamate)oxovanadium(V), VO(15)NGlySalbz. We then apply this approach to derive the three-dimensional structure of (methoxo)((15)N-salicylidene-glycinato)oxovanadium(V) with solvated methanol, [VO((15)NGlySal)(OCH3)]·(CH3OH). This is a representative complex with potentially variable coordination geometry depending on the solvation level of the solid. The solid material containing molecules of CH3OH, formally expressed as [VO((15)NGlySal)(OCH3)]·(CH3OH), is found to have one molecule of CH3OH weakly coordinated to the vanadium. The material is therefore best described as [VO((15)NGlySal)(OCH3)(CH3OH)] as deduced by the combination of multinuclear solid-state NMR experiments and DFT calculations. The approach reported here can be used for structural analysis of systems that are not amenable to single-crystal X-ray diffraction characterization and which can contain weakly associated solvents. PMID:25590382

Li, Mingyue; Yehl, Jenna; Hou, Guangjin; Chatterjee, Pabitra B; Goldbourt, Amir; Crans, Debbie C; Polenova, Tatyana

2015-02-16

8

Reversible and selective solvent adsorption in layered metal-organic frameworks by coordination control.  

PubMed

With various functionalities in the framework and high thermal stability, metal-organic frameworks (MOFs) have been extensively studied for the applications in adsorption and separation. In last decade, synthesizing new MOFs with desired structures and improved chemical stability to meet these applications has drawn great attention. In this report, by using an organic ligand with azolate moiety, benzo-bis(imidazole) (H2BBI), we synthesized two new 2D layered MOF structures with distinct topologies. Framework 1 {[Zn2Cl2(BBI)(MSM)2]n, MSM=methylsulfonylmethane}, constructed from tetrahedral Zn(II) and BBI, maintains its structure in organic solvents, such as methanol and benzene, and even in water. Meanwhile, framework 2 {[Cd2Cl2(BBI)(DMSO)2]n, DMSO=dimethyl sulfoxide} differs from framework 1, and is assembled from trigonal bipyramidal Cd(II) and square planar BBI. By removing the DMSO molecules coordinated to Cd(II) (25 weight% of the structure), 2 could transform to 3 {[Cd2Cl2(BBI)]n}, which was further characterized by high-resolution powder X-ray diffraction. The solvent-free 3 retains the original connectivity within each layer, and is capable of reversible and selective adsorption of DMSO molecules. The bistable four- and five-coordinated geometry exchange of Cd(II) is the origin of this adsorption with improved selectivity and capacity. PMID:24183447

Yin, Xinbo; Chen, Haohong; Song, Yuna; Wang, Yang; Li, Qiaowei; Zhang, Lijuan

2014-01-01

9

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

SciTech Connect

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 Mg{sub 4}(3,5-PDC){sub 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 multiple desolvation routes, we were unable to measure BET surface areas greater than 51.9 m{sup 2}/g for compound 1.

D Banerjee; J Finkelstein; A Smirnov; P Forster; L Borkowski; S Teat; J Parise

2011-12-31

10

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

SciTech Connect

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 multiple desolvation routes, we were unable to measure BET surface areas greater than 51.9 m{sup 2}/g for compound 1.

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

2012-10-11

11

Synthesis and properties of the weakly coordinating anion [Me3 NB12 Cl11 ](-).  

PubMed

The weakly coordinating anion [Me3 NB12 Cl11 ](-) has been prepared by a simple two-step procedure. The anion [Me3 NB12 Cl11 ](-) is easily obtained in batches of up to 20 g by chlorination of the known [H3 NB12 H11 ](-) anion with SbCl5 at about 190?°C and subsequent N-methylation with methyl iodide. Starting from Na[Me3 NB12 Cl11 ], several synthetically useful salts with reactive cations ([NO](+) , [Ph3 C](+) , and [(Et3 Si)2 H](+) ) were prepared. Full spectroscopic (NMR, IR, Raman, TGA, MS) characterization and single-crystal X-ray diffraction studies confirmed the identity and purity of the products. The thermal, chemical, and electrochemical stability as well as the basicity of the [Me3 NB12 Cl11 ](-) anion is similar to that of the structurally related weakly coordinating 1-carba-closo-dodecaborate and closo-dodecaborate anions. The facile preparation of the [Me3 NB12 Cl11 ](-) anion and its ideal chemical and physical properties make it a cheap alternative to other classes of weakly coordinating anions. PMID:25196859

Bolli, Christoph; Derendorf, Janis; Jenne, Carsten; Scherer, Harald; Sindlinger, Christian P; Wegener, Bianca

2014-10-13

12

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

PubMed

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[double bond, length as m-dash]Ca-Cb-O-Cb-Ca[double bond, length as m-dash]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. PMID:25310364

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

2015-01-14

13

Modulation of electronics and thermal stabilities of photochromic phosphino-aminoazobenzene derivatives in weak-link approach coordination complexes.  

PubMed

A series of d(8) transition-metal (Pt(II) and Pd(II)) coordination complexes incorporating phosphine-functionalized aminoazobenzene derivatives as hemilabile phosphino-amine (P,N) ligands were synthesized and studied as model weak-link approach (WLA) photoresponsive constructs. The optical and photochemical properties of these complexes were found to be highly influenced by various tunable parameters in WLA systems, which include type of metal, coordination mode, type of ancillary ligand, solvent, and outer-sphere counteranions. In dichloromethane, reversible chelation and partial displacement of the P,N coordinating moieties allow for toggling between aminoazobenzene- or pseudostilbene- and azobenzene-type derivatives. The reversible switching between electronic states of azobenzene can be controlled through either addition or extraction of chloride counterions and is readily visualized in the separation between ?-?* and n-?* bands in the complexes' electronic spectra. In acetonitrile solution, the WLA variables inherent to semiopen complexes have a significant impact on the half-lives of the corresponding cis isomers, allowing one to tune their half-lives from 20 to 21000 s, while maintaining photoisomerization behaviors with visible light. Therefore, one can significantly increase the thermal stability of a cis-aminoazobenzene derivative to the extent that single crystals for X-ray diffraction analysis can be grown for the first time, uncovering an unprecedented edge-to-face arrangement of the phenyl rings in the cis isomer. Overall, the azobenzene-functionalized model complexes shed light on the design parameters relevant for photocontrolled WLA molecular switches, as well as offer new ways of tuning the properties of azobenzene-based, photoresponsive materials. PMID:24187977

Park, Jung Su; Lifschitz, Alejo M; Young, Ryan M; Mendez-Arroyo, Jose; Wasielewski, Michael R; Stern, Charlotte L; Mirkin, Chad A

2013-11-13

14

Deformed coordinate-space Hartree-Fock-Bogoliubov approach to weakly bound nuclei and large deformations  

NASA Astrophysics Data System (ADS)

The coordinate-space formulation of the Hartree-Fock-Bogoliubov (HFB) method enables the self-consistent treatment of mean field and pairing in weakly bound systems whose properties are affected by the particle continuum space. Of particular interest are neutron-rich, deformed drip-line nuclei, which can exhibit novel properties associated with neutron skin. To describe such systems theoretically, we developed an accurate two-dimensional lattice Skyrme-HFB solver HFB-AX based on basis (or B)-splines. Compared to previous implementations, ours incorporated a number of improvements aimed at boosting the solver's performance. These include the explicit imposition of axiality and space inversion, use of the modified Broyden method to solve self-consistent equations, and a partial parallelization of the code. HFB-AX has been compared with other HFB codes, both spherical and deformed, and the accuracy of the B-spline expansion was tested by employing the multiresolution wavelet method. Illustrative calculations are carried out for stable and weakly bound nuclei at spherical and very deformed shapes, including constrained fission pathways. In addition to providing new physics insights, HFB-AX can serve as a useful tool to assess the reliability and applicability of coordinate-space and configuration-space HFB frameworks, both existing and in development.

Pei, J. C.; Stoitsov, M. V.; Fann, G. I.; Nazarewicz, W.; Schunck, N.; Xu, F. R.

2008-12-01

15

Deformed Coordinate-Space Hartree-Fock-Bogoliubov Approach to Weakly Bound Nuclei and Large Deformations  

E-print Network

The coordinate space formulation of the Hartree-Fock-Bogoliubov (HFB) method enables self-consistent treatment of mean-field and pairing in weakly bound systems whose properties are affected by the particle continuum space. Of particular interest are neutron-rich, deformed drip-line nuclei which can exhibit novel properties associated with neutron skin. To describe such systems theoretically, we developed an accurate 2D lattice Skyrme-HFB solver {\\hfbax} based on B-splines. Compared to previous implementations, we made a number of improvements aimed at boosting the solver's performance. These include: explicit imposition of axiality and space inversion, use of the modified Broyden's method to solve self-consistent equations, and a partial parallelization of the code. {\\hfbax} has been benchmarked against other HFB solvers, both spherical and deformed, and the accuracy of the B-spline expansion was tested by employing the multiresolution wavelet method. Illustrative calculations are carried out for stable and weakly bound nuclei at spherical and very deformed shapes, including constrained fission pathways. In addition to providing new physics insights, {\\hfbax} can serve as a useful tool to assess the reliability and applicability of coordinate-space and configuration-space HFB solvers, both existing and in development.

J. C. Pei; M. V. Stoitsov; G. I. Fann; W. Nazarewicz; N. Schunck; F. R. Xu

2008-07-18

16

Retrieval-based face annotation by weak label regularized local coordinate coding.  

PubMed

Auto face annotation, which aims to detect human faces from a facial image and assign them proper human names, is a fundamental research problem and beneficial to many real-world applications. In this work, we address this problem by investigating a retrieval-based annotation scheme of mining massive web facial images that are freely available over the Internet. In particular, given a facial image, we first retrieve the top $(n)$ similar instances from a large-scale web facial image database using content-based image retrieval techniques, and then use their labels for auto annotation. Such a scheme has two major challenges: 1) how to retrieve the similar facial images that truly match the query, and 2) how to exploit the noisy labels of the top similar facial images, which may be incorrect or incomplete due to the nature of web images. In this paper, we propose an effective Weak Label Regularized Local Coordinate Coding (WLRLCC) technique, which exploits the principle of local coordinate coding by learning sparse features, and employs the idea of graph-based weak label regularization to enhance the weak labels of the similar facial images. An efficient optimization algorithm is proposed to solve the WLRLCC problem. Moreover, an effective sparse reconstruction scheme is developed to perform the face annotation task. We conduct extensive empirical studies on several web facial image databases to evaluate the proposed WLRLCC algorithm from different aspects. The experimental results validate its efficacy. We share the two constructed databases "WDB" (714,454 images of 6,025 people) and "ADB" (126,070 images of 1,200 people) with the public. To further improve the efficiency and scalability, we also propose an offline approximation scheme (AWLRLCC) which generally maintains comparable results but significantly reduces the annotation time. PMID:24457510

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

2014-03-01

17

Deformed Coordinate-Space Hartree-Fock-Bogoliubov Approach to Weakly Bound Nuclei and Large Deformations  

E-print Network

The coordinate space formulation of the Hartree-Fock-Bogoliubov (HFB) method enables self-consistent treatment of mean-field and pairing in weakly bound systems whose properties are affected by the particle continuum space. Of particular interest are neutron-rich, deformed drip-line nuclei which can exhibit novel properties associated with neutron skin. To describe such systems theoretically, we developed an accurate 2D lattice Skyrme-HFB solver {\\hfbax} based on B-splines. Compared to previous implementations, we made a number of improvements aimed at boosting the solver's performance. These include: explicit imposition of axiality and space inversion, use of the modified Broyden's method to solve self-consistent equations, and a partial parallelization of the code. {\\hfbax} has been benchmarked against other HFB solvers, both spherical and deformed, and the accuracy of the B-spline expansion was tested by employing the multiresolution wavelet method. Illustrative calculations are carried out for stable and ...

Pei, J C; Fann, G I; Nazarewicz, W; Schunck, N; Xu, F R

2008-01-01

18

Solvent-induced structural dynamics in noninterpenetrating porous coordination polymeric networks.  

PubMed

Three novel soft porous coordination polymer (PCP) or metal-organic framework (MOF) compounds have been synthesized with a new rigid ligand N-(4-pyridyl)-1,4,5,8-naphathalenetetracarboxymonoimide (PNMI) by partial hydrolysis of N,N'-di-(4-pyridyl)-1,4,5,8-naphthalenete-tracarboxydiimide (DPNI) during solvothermal reactions with Zn(II), Cd(II), and Mn(II) salts, and they are [Zn(PNMI)]·2DMA (1·2DMA, 1a), [Cd(PNMI)]·0.5DMA·5H2O (2·0.5DMA·5H2O), and [Mn(PNMI)]·0.75DMF (3·0.75DMF). The structure of 1 is based on paddle-wheel secondary building unit (SBU) with a 3,6-connected rtl net topology, whereas 2 and 3 are isotypical but the M(O2C-C)2 fragments aggregate in one-dimension and the overall connectivity is the same rtl net topology. All these three MOFs have one-dimensional rhombic channels filled with guest molecules. The guest molecules in 1a can be exchanged with EtOH in a single-crystal to single-crystal (SCSC) manner to 1·1.25EtOH·0.375H2O (1b). Further, the guest molecules in 1b can be replaced with ethylene glycol, triethylene glycol and allyl alcohol without destroying its single crystal nature. These guest exchanges are accompanied by reduction in volume of the unit cell up to 16%, as well as the void volume up to 33.1%. Similarly, triethylene glycol (TEGly) selectively exchanges EtOH in a mixture of the above solvents, which might be the result of correct fit of the hydrogen-bonded TEGly dimer in the channel of 1. While activated 1 and 3 exhibit no uptake of N2 and H2 at 1 bar and 77 K and very low uptake of CO2 gas at 1 bar and 196 K, activated 2 shows selective CO2 uptake, 278 cm(2)·g(-1), over N2 and H2 at 1 bar and 196 K, which corresponds to 5.87 molecules of CO2 per formula unit of 2. PMID:23452045

Medishetty, Raghavender; Jung, Daram; Song, Xiaokai; Kim, Dongwook; Lee, Shim Sung; Lah, Myoung Soo; Vittal, Jagadese J

2013-03-18

19

Investigations of iron coordination and redox reactions in seawater using 59Fe radiometry and ion-pair solvent extraction of amphiphilic iron complexes  

Microsoft Academic Search

Hudson, R.J.M., Covault, D.T. and Morel, F.M.M., 1992. Investigations of iron coordination and redox reactions in seawater using 59Fe radiometry and ion-pair solvent extraction of amphiphilic iron complexes. Mar. Chem., 38: 209-235. Iron coordination and redox reactions in synthetic and coastal seawater were investigated at na- nomolar concentrations using 59Fe radiometry and ion-pair solvent extraction of iron chelated by sulfoxine

Robert J. M. Hudson; Dianne T. Covault; Francois M. M. Morel

1992-01-01

20

Solvent induced rapid modulation of micro/nano structures of metal carboxylates coordination polymers: mechanism and morphology dependent magnetism.  

PubMed

Rational modulation of morphology is very important for functional coordination polymers (CPs) micro/nanostructures, and new strategies are still desired to achieve this challenging target. Herein, organic solvents have been established as the capping agents for rapid modulating the growth of metal-carboxylates CPs in organic solvent/water mixtures at ambient conditions. Co-3,5-pyridinedicarboxylate (pydc) CPs was studied here as the example. During the reaction, the organic solvents exhibited three types of modulation effect: anisotropic growth, anisotropic growth/formation of new crystalline phase and the formation of new crystalline phase solely, which was due to the variation of their binding ability with metal cations. The following study revealed that the binding ability was critically affected by their functional groups and molecular size. Moreover, their modulation effect could be finely tuned by changing volume ratios of solvent mixtures. Furthermore, they could be applied for modulating other metal-carboxylates CPs: Co-1,3,5-benzenetricarboxylic (BTC), Zn-pydc and Eu-pydc etc. Additionally, the as-prepared Co-pydc CPs showed a fascinating morphology-dependent antiferromagnetic behavior. PMID:25113225

Liu, Kun; Shen, Zhu-Rui; Li, Yue; Han, Song-De; Hu, Tong-Liang; Zhang, Da-Shuai; Bu, Xian-He; Ruan, Wen-Juan

2014-01-01

21

Solvent induced rapid modulation of micro/nano structures of metal carboxylates coordination polymers: mechanism and morphology dependent magnetism  

PubMed Central

Rational modulation of morphology is very important for functional coordination polymers (CPs) micro/nanostructures, and new strategies are still desired to achieve this challenging target. Herein, organic solvents have been established as the capping agents for rapid modulating the growth of metal-carboxylates CPs in organic solvent/water mixtures at ambient conditions. Co-3,5-pyridinedicarboxylate (pydc) CPs was studied here as the example. During the reaction, the organic solvents exhibited three types of modulation effect: anisotropic growth, anisotropic growth/formation of new crystalline phase and the formation of new crystalline phase solely, which was due to the variation of their binding ability with metal cations. The following study revealed that the binding ability was critically affected by their functional groups and molecular size. Moreover, their modulation effect could be finely tuned by changing volume ratios of solvent mixtures. Furthermore, they could be applied for modulating other metal-carboxylates CPs: Co-1,3,5-benzenetricarboxylic (BTC), Zn-pydc and Eu-pydc etc. Additionally, the as-prepared Co-pydc CPs showed a fascinating morphology-dependent antiferromagnetic behavior. PMID:25113225

Liu, Kun; Shen, Zhu-Rui; Li, Yue; Han, Song-De; Hu, Tong-Liang; Zhang, Da-Shuai; Bu, Xian-He; Ruan, Wen-Juan

2014-01-01

22

Coordinates  

NSDL National Science Digital Library

This introduction to the labeling of points on a plane by their Cartesian coordinates can optionally be extended to coordinates in 3-dimensional space, to plane polar coordinates and to 3-dimensional polar coordinates. Students should learn to use Cartesian coordinates (x,y) for defining the position of a point in two dimensions and to use Cartesian coordinates (x,y,z) in 3-dimensional space and learn to appreciate the two ways of defining the z axis. Students should also become familiar with some of the tools and terms used by surveyors such as theodolite, azimuth, elevation, and zenith. Optional items for students familiar with trigonometry and with the theorem of Pythagoras are polar coordinates (r,f ) on the plane, Converting (r,f) to (x,y) and vice versa, at least for r, and Spherical polar coordinates (r,q, f) in 3-dimensional space.

Stern, David

23

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)

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.

Sayin, Koray; Karaka?, Duran

2014-11-01

24

Electrophilic Ln(III) cations protected by C-F ? Ln interactions and their coordination chemistry with weak ?- and ?-donors.  

PubMed

A homoleptic cerium(III) amide complex, Ce(NPh(F)2)3 (1-Ce) (Ph(F) = pentafluorophenyl), in an unusual pseudo-trigonal planar geometry featuring six C-F ? Ce interactions was prepared. The C-F ? Ln interactions in solution were evident by comparison of the (19)F NMR shifts for the paramagnetic 1-Ce with those of the 4f(0) lanthanum(III) analogue. Coordination of weak ?- and ?-donors, including ethers and neutral arene molecules, was achieved by the reversible displacement of the weak C-F ? Ce interactions. Computational studies on Ce(NPh(F)2)3 and Ce(NPh(F)2)3(?(6)-C6H3Me3) provide information on the F ? Ce interactions and Ce-?(6)-arene bonding. PMID:23802923

Yin, Haolin; Lewis, Andrew J; Carroll, Patrick; Schelter, Eric J

2013-07-15

25

Origin of strong synergism in weakly perturbed binary solvent system: a case study of primary alcohols and chlorinated methanes.  

PubMed

A strong synergistic solvation was observed for the mixtures of hydrogen bond donating and accepting solvent pairs. The nature of the interactions between two solvent pairs was investigated with different dye molecules viz. coumarin 480, coumarin 153, 4-aminophthalimide, and p-nitroaniline. Coumarin 480 in differenet alcohols-CHCl(3) (alcohols: MeOH, EtOH, BuOH) binary mixture shows a strong synergism, which is explained in the backdrop of solvent-solvent interactions. Fluorescence quenching of C480 by 1,2-phenylenediamine in the binary solvent mixture exhibited the maximum deviation in quenching constant corresponding to ~0.45 mol fraction of MeOH in MeOH-CHCl(3) binary mixture and hence suggested the maximum extent of hydrogen-bonding interactions prevailing at this proportion of mixture. The solvation behavior of MeOH-CHCl(3) mixture shows strong probe dependence with no synergism observed in p-nitroaniline, which is ascribed to its higher ground state dipole moment (8.8 D) relative to C480 (6.3 D). Interestingly, the strong synergistic signature observed through spectrophotometric measurement of C480 in alcohol-CHCl(3) binary mixture is absent when studied by fluorescence measurement. The higher excited state dipole moment of coumarin 480 (13.1 D) is considered to be the driving force for the absence of synergism in the excited state. In such strongly perturbed systems (due to high dipole moment values) the dominant phenomenon is preferential solvation. Analysis of proton NMR of MeOH-CHCl(3) binary solvent mixture indicates the existence of MeOH-CHCl(3) clusters in the stoichiometric ratio of 1:2.15. Refractive index measurement also infers the existence of hydrogen bonded network structure between MeOH and CHCl(3). A modified Bosch solvent exchange model has been used to determine the feasibility of synergistic behavior and polarity parameter of the mixed solvent structure of MeOH-CHCl(3) binary solvent mixture. PMID:22200245

Gupta, Shradhey; Rafiq, Shahnawaz; Kundu, Mainak; Sen, Pratik

2012-02-01

26

Stannylium ions, a tin(II) arene complex, and a tin dication stabilized by weakly coordinating anions.  

PubMed

The reactivity of aryl-substituted stannylenes, Ar(2)Sn (4), towards silylarenium borates, [R(3)SiArH][B(C(6)F(5))(4)] (3), was investigated. The reaction with 2,3,4-trimethyl-6-tert-butylphenyl (mebp)-substituted stannylene gave silyl-substituted stannylium ions 2a,b, which were characterized by NMR spectroscopy supported by the results of quantum-mechanical computations of molecular structures and magnetic properties. The tri-iso-propylphenyl-substituted stannylium ions 2c,d undergo a decomposition reaction in toluene to give the dicationic tin-arene complex [Sn(C(7)H(8))(3)](2+) (5) in the form of the [B(C(6)F(5))(4)] salt in high yields. The 5[B(C(6)F(5))(4)](2) salt was identified by single crystal X-ray diffraction analysis and by Mössbauer spectroscopy. The bonding situation was investigated by using natural bond orbital (NBO) and quantum theory of atoms in molecules (QTAIM) calculations. The substitution of the weakly coordinating borate anion by the carboranate [CB(11)H(6)Br(6)](-) results in replacement of the toluene ligands and formation of tin(II) carboranate with only weak Sn(2+)-anion interactions as suggested by the solid-state structure of the isolated salt. PMID:21919092

Schäfer, Annemarie; Winter, Florian; Saak, Wolfgang; Haase, Detlev; Pöttgen, Rainer; Müller, Thomas

2011-09-19

27

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

SciTech Connect

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.

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

2011-12-31

28

Coordinated study of non-seismic and weak seismic events (magnitude M less than 5) using VLF radio links  

NASA Astrophysics Data System (ADS)

In this study we analyze low seismicity earthquakes (EQs) with magnitudes M < 5 in South Eastern Europe, time period 2011-2013, via very low frequency (VLF) radio links. The main scientific objective of the statistical and event based investigations are reliable characterization of typical seismic and non-seismic variations in the VLF signal. The focus is on robust results, especially for weak EQs, because non-seismic influences could have a strong effect on the analysis. Various electromagnetic methods have been developed in order to study possible earthquake precursor phenomena generated in the lithosphere and then propagating in the atmosphere / ionosphere [1]. The major challenge of this seismo-electromagnetic (SEM) method is to differentiate parameter variations and disentangle seismic from non-seismic sources. In the course of the European radio receiver network (International Network for Frontier Research on Earthquake Precursors, INFREP) radio signals in the VLF/LF frequency range are continuously recorded by dedicated, distributed transmitters. The major VLF receiving station for this study (10-50 kHz, Graz, Austria) operates continuously throughout the year, the selected network-wide temporal resolution is 20 sec, 12 transmitters, located mainly in Europe, are received (amplitude and phase). The facility has a proven high reliability and availability. The VLF links from the transmitters to the receivers are sometimes more, sometimes less influenced by various disturbances. In case the signal is crossing an EQ preparation zone, we are in principle able to detect seismic activity if the signal to noise ratio is high enough [2]. Generally we distinguish between ionospheric or atmospheric disturbances, influences which depend on the EQ properties, and transmitter variations itself. Ionospheric / Atmospheric variations can be generated, e.g. by geomagnetic storms, solar flares or waves in the troposphere. The properties of the sub-ionospheric VLF waveguide are affected by the length of the radio path, the distance to the EQ preparation zone, the parameters of the earthquake (magnitude, depth, type), and daytime / nighttime disturbances. In order to minimize ionospheric influences on the radio path we are considering mainly nighttime periods. Beside the terminator time method, where only the VLF sunrise and sunset period is analyzed, we are using the residual method (2 hours before and after local midnight), where the difference between the monthly mean amplitude and the nighttime variation is calculated. Anomalous signal variations outside the two sigma borderline are used to determine possible seismo-electromagnetic events. We conclude that the coordinated study of seismic and non-seismic signals in VLF links is an essential part in SEM investigations, but - as an outlook - shall be supplemented with complementary methods that explore a wider frequency range. References: [1] O. Molchanov, M. Hayakawa: Seismo-Electromagnetics and related Phenomena: History and latest results, Terrapub, 2008. [2] A. Rozhnoi et al.: Anomalies in VLF radio signals prior Abruzzo earthquake (M=6.3) on 6 April 2009, National Hazards and Earth System Sciences, 9, 1727-1732, 2009.

Wolbang, Daniel; Biernat, Helfried K.; Friedrich, Martin; Schwingenschuh, Konrad; Besser, B. P.; Eichelberger, Hans; Prattes, Gustav; Rozhnoi, Alexander; Solovieva, Maria; Biagi, Pier Francesco; Boudjada, Mohammed Y.

29

Silver-Free Activation of Ligated Gold(I) Chlorides: The Use of [Me3 NB12 Cl11 ](-) as a Weakly Coordinating Anion in Homogeneous Gold Catalysis.  

PubMed

Phosphane and N-heterocyclic carbene ligated gold(I) chlorides can be effectively activated by Na[Me3 NB12 Cl11 ] (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. PMID:25394284

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

2014-11-13

30

Boron-dipyrromethene-functionalized hemilabile ligands as "turn-on" fluorescent probes for coordination changes in weak-link approach complexes.  

PubMed

Herein we report a new class of hemilabile ligands with boron-dipyrromethene (Bodipy) fluorophores that, when complexed to Pt(II), can signal changes in coordination mode through changes in their fluorescence. The ligands consist of phosphino-amine or phosphino-thioether coordinating moieties linked to the Bodipy's meso carbon via a phenylene spacer. Interestingly, this new class of ligands can be used to signal both ligand displacement and chelation reactions in a fluorescence "turn-on" fashion through the choice of weakly binding heteroatom in the hemilabile moiety, generating up to 10-fold fluorescence intensity increases. The Pt(II) center influences the Bodipy emission efficiency by regulating photoinduced electron transfer between the fluorophore and its meso substituent. The rates at which the excited Bodipy-species generate singlet oxygen upon excitation suggest that the heavy Pt(II) center also influences Bodipy's emission efficiency by affecting intersystem crossing from the Bodipy excited singlet to excited triplet states. This signaling strategy provides a quantitative read-out for changes in coordination mode and potentially will enable the design of new molecular systems for sensing and signal amplification. PMID:23570551

Lifschitz, Alejo M; Shade, Chad M; Spokoyny, Alexander M; Mendez-Arroyo, Jose; Stern, Charlotte L; Sarjeant, Amy A; Mirkin, Chad A

2013-05-01

31

Microscopic solvation of a lithium atom in water-ammonia mixed clusters: Solvent coordination and electron localization in presence of a counterion  

SciTech Connect

The microsolvation structures and energetics of water-ammonia mixed clusters containing a lithium atom, i.e., Li(H{sub 2}O){sub n}(NH{sub 3}), n=1-5, are investigated by means of ab initio theoretical calculations. Several structural aspects such as the solvent coordination to the metal ion and binding motifs of the free valence electron of the metal are investigated. We also study the energetics aspects such as the dependence of vertical ionization energies on the cluster size, and all these structural and energetics aspects are compared to the corresponding results of previously studied anionic water-ammonia clusters without a metal ion. It is found that the Li-O and Li-N interactions play a very important role in stabilizing the lithium-water-ammonia clusters, and the presence of these metal ion-solvent interactions also affect the characteristics of electron solvation in these clusters. This is seen from the spatial distribution of the singly occupied molecular orbital (SOMO) which holds the ejected valence electron of the Li atom. For very small clusters, SOMO electron density is found to exist mainly at the vicinity of the Li atom, whereas for larger clusters, it is distributed outside the first solvation shell. The free dangling hydrogens of water and ammonia molecules are involved in capturing the SOMO electron density. In some of the conformers, OH(e)HO and OH(e)HN types of interactions are found to be present. The presence of the metal ion at the center of the cluster ensures that the ejected electron is solvated at a surface state only, whereas both surface and interiorlike states were found for the free electron in the corresponding anionic clusters without a metal ion. The vertical ionization energies of the present clusters are found to be higher than the vertical detachment energies of the corresponding anionic clusters which signify a relatively stronger binding of the free electron in the presence of the positive metal counterion. The shifts in different vibrational frequencies are also calculated for the larger clusters, and the results are discussed for some of the selective modes of water and ammonia molecules that are directly influenced by the location and hydrogen bonding state of these molecules in the clusters.

Pratihar, Subha; Chandra, Amalendu [Department of Chemistry, Indian Institute of Technology, Kanpur 208016 (India)

2008-07-14

32

Microscopic solvation of a lithium atom in water-ammonia mixed clusters: Solvent coordination and electron localization in presence of a counterion  

NASA Astrophysics Data System (ADS)

The microsolvation structures and energetics of water-ammonia mixed clusters containing a lithium atom, i.e., Li(H2O)n(NH3), n =1-5, are investigated by means of ab initio theoretical calculations. Several structural aspects such as the solvent coordination to the metal ion and binding motifs of the free valence electron of the metal are investigated. We also study the energetics aspects such as the dependence of vertical ionization energies on the cluster size, and all these structural and energetics aspects are compared to the corresponding results of previously studied anionic water-ammonia clusters without a metal ion. It is found that the Li-O and Li-N interactions play a very important role in stabilizing the lithium-water-ammonia clusters, and the presence of these metal ion-solvent interactions also affect the characteristics of electron solvation in these clusters. This is seen from the spatial distribution of the singly occupied molecular orbital (SOMO) which holds the ejected valence electron of the Li atom. For very small clusters, SOMO electron density is found to exist mainly at the vicinity of the Li atom, whereas for larger clusters, it is distributed outside the first solvation shell. The free dangling hydrogens of water and ammonia molecules are involved in capturing the SOMO electron density. In some of the conformers, OH{e}HO and OH{e}HN types of interactions are found to be present. The presence of the metal ion at the center of the cluster ensures that the ejected electron is solvated at a surface state only, whereas both surface and interiorlike states were found for the free electron in the corresponding anionic clusters without a metal ion. The vertical ionization energies of the present clusters are found to be higher than the vertical detachment energies of the corresponding anionic clusters which signify a relatively stronger binding of the free electron in the presence of the positive metal counterion. The shifts in different vibrational frequencies are also calculated for the larger clusters, and the results are discussed for some of the selective modes of water and ammonia molecules that are directly influenced by the location and hydrogen bonding state of these molecules in the clusters.

Pratihar, Subha; Chandra, Amalendu

2008-07-01

33

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

We report single-crystal X-band EPR and magnetic measurements of the coordination polymer catena-(trans-(?2-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. PMID:24528370

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

2014-03-01

34

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

PubMed Central

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)(?-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)(?-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)(?-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(?-OH)4(?-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(?-O)3(H2O)2](BF4)·8DMF (8) and [Fe4(N-Et-HPTB)2(?-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

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

2014-01-01

35

Dissolution of Metal Salts in Bis(trifluoromethylsulfonyl)imide-Based Ionic Liquids: Studying the Affinity of Metal Cations Toward a "Weakly Coordinating" Anion.  

PubMed

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

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

2014-11-13

36

Solvent interactions with a triphenylated benzoxazole polymer  

E-print Network

solubility parameter for the pclymer, A for the solvent, and Hansen's polar solubility parameters for the solvent and polymer indicated that the best solvents of tripheny- lated PBO would be m-cresol, phenol, and the carboxylic acids. Laboratory tests... for this lack of solubility, at least in the case of PBO, might be due to the morphology of the material heing such that solvent diffusion is not possible to many polymer chains by large, weakly interacti. ng solvents. However, diffusion is observed...

Eversdyk, David Allen

2012-06-07

37

Smooth landscape solvent dynamics in electron transfer reactions  

NASA Astrophysics Data System (ADS)

Solvent effects play a major role in controlling electron-transfer reactions. The solvent dynamics happens on a very high-dimensional surface, and this complex landscape is populated by a large number of minima. A critical problem is to understand the conditions under which the solvent dynamics can be represented by a single collective reaction coordinate. When this unidimensional representation is valid, one recovers the successful Marcus theory. In this study the approach used in a previous work [V. B. P. Leite and J. N. Onuchic; J. Phys. Chem. 100, 7680 (1996)] is extended to treat a more realistic solvent model, which includes energy correlation. The dynamics takes place in a smooth and well behaved landscape. The single shell of solvent molecules around a cavity is described by a two-dimensional system with periodic boundary conditions with nearest neighbor interaction. It is shown how the polarization-dependent effects can be inferred. The existence of phase transitions depends on a factor ? proportional to the contribution from the two parameters of the model. For the present model, ? suggests the existence of "weak kinetic phase transitions," which are used in the analysis of solvent effects in charge-transfer reactions.

Leite, Vitor B. P.

1999-05-01

38

Toward advanced ionic liquids. Polar, enzyme-friendly solvents for biocatalysis  

Microsoft Academic Search

Ionic liquids, also called molten salts, are mixtures of cations and anions that melt below 100°C. Typical ionic liquids are\\u000a dialkylimidazolium cations with weakly coordinating anions such as (MeOSO3) or (PF6). Advanced ionic liquids such as choline citrate have biodegradable, less expensive, and less toxic anions and cations. Deep\\u000a eutectic solvents are also included in the advanced ionic liquids. Deep

Johnathan Gorke; Friedrich Srienc; Romas Kazlauskas

2010-01-01

39

Solvent density inhomogeneities and solvation free energies in supercritical diatomic fluids: a density functional approach.  

PubMed

Density functional theory is used to explore the solvation properties of a spherical solute immersed in a supercritical diatomic fluid. The solute is modeled as a hard core Yukawa particle surrounded by a diatomic Lennard-Jones fluid represented by two fused tangent spheres using an interaction site approximation. The authors' approach is particularly suitable for thoroughly exploring the effect of different interaction parameters, such as solute-solvent interaction strength and range, solvent-solvent long-range interactions, and particle size, on the local solvent structure and the solvation free energy under supercritical conditions. Their results indicate that the behavior of the local coordination number in homonuclear diatomic fluids follows trends similar to those reported in previous studies for monatomic fluids. The local density augmentation is particularly sensitive to changes in solute size and is affected to a lesser degree by variations in the solute-solvent interaction strength and range. The associated solvation free energies exhibit a nonmonotonous behavior as a function of density for systems with weak solute-solvent interactions. The authors' results suggest that solute-solvent interaction anisotropies have a major influence on the nature and extent of local solvent density inhomogeneities and on the value of the solvation free energies in supercritical solutions of heteronuclear molecules. PMID:17302486

Husowitz, B; Talanquer, V

2007-02-01

40

Coordination chemistry of the solvated silver(I) ion in the oxygen donor solvents water, dimethyl sulfoxide, and N,N'-dimethylpropyleneurea.  

PubMed

The hydrated and dimethyl sulfoxide and N,N'-dimethylpropyleneurea solvated silver(I) ions have been characterized structurally in solution by means of extended X-ray absorption fine structure (EXAFS) and large-angle X-ray scattering (LAXS). The coordination chemistry of the hydrated and dimethyl sulfoxide solvated silver(I) ions has been reevaluated because of different results from the EXAFS and LAXS methods reported previously. Consistent results are obtained with a linearly distorted tetrahedral model with two short and approximately two long Ag-O bond distances: mean Ag-O bond lengths of 2.32(1) and 2.54(1) A for the hydrate, 2.31(1) and 2.48(2) A for the dimethyl sulfoxide solvate, and 2.31(1) and 2.54(2) A for the N,N'-dimethylpropyleneurea solvate, in solution. PMID:16933947

Persson, Ingmar; Nilsson, Kersti B

2006-09-01

41

Comparative DNA binding abilities and phosphatase-like activities of mono-, di-, and trinuclear Ni(II) complexes: the influence of ligand denticity, metal-metal distance, and coordinating solvent/anion on kinetics studies.  

PubMed

Six novel Ni(II) complexes, namely, [Ni2(HL(1))(OAc)2] (1), [Ni3L(1)2]·H2O·2CH3CN (2), [Ni2(L(2))(L(3))(CH3CN)] (3), [Ni2(L(2))2(H2O)2] (4), [Ni2(L(2))2(DMF)2]2·2H2O (5), and [Ni(HL(2))2]·H2O (6), were synthesized by reacting nitrophenol-based tripodal (H3L(1)) and dipodal (H2L(2)) Schiff base ligands with Ni(II) metal salts at ambient conditions. All the complexes were fully characterized with different spectroscopic techniques such as elemental analyses, IR, UV-vis spectroscopy, and electrospray ionization mass spectrometry. The solid-state structures of 2, 3, 5, and 6 were determined using single-crystal X-ray crystallography. The compounds 1, 3, 4, and 5 are dinuclear complexes where the two Ni(II) centers have octahedral geometry with bridging phenoxo groups. Compound 2 is a trinuclear complex with two different types of Ni(II) centers. In compound 3 one of the Ni(II) centers has a coordinated acetonitrile molecule, whereas in compound 4, a water molecule has occupied one coordination site of each Ni(II) center. In complex 5, the coordinated water of complex 4 was displaced by the dimethylformamide (DMF) during its crystallization. Complex 6 is mononuclear with two amine-bis(phenolate) ligands in scissorlike fashion around the Ni(II) metal center. The single crystals of 1 and 4 could not be obtained; however, from the spectroscopic data and physicochemical properties (electronic and redox properties) it was assumed that the structures of these complexes are quite similar to other analogues. DNA binding abilities and phosphatase-like activities of all characterized complexes were also investigated. The ligand denticity, coordinated anions/solvents (such as acetate, acetonitrile, water, and DMF), and cooperative action of two metal centers play a significant role in the phosphate ester bond cleavage of 2-hydroxypropyl-p-nitropenylphosphate by transesterification mechanism. Complex 3 exhibits highest activity among complexes 1-6 with 3.86 × 10(5) times greater rate enhancement than uncatalyzed reaction. PMID:25226493

Bhardwaj, Vimal K; Singh, Ajnesh

2014-10-01

42

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

We herein describe a coordination polymer system built upon the reactions of a W/Cu/S cluster precursor [Et4N][Tp*WS3(CuBr)3] (, Tp* = hydridotris(3,5-dimethylpyrazol-1-yl)borate) with three equivalents of CuCN through solvent modulation. Four coordination polymers, namely, [Tp*WS3Cu3(?3-DMF)(CN)3Cu(Py)] (), [Tp*WS3Cu3(?3-DMF)(CN)3Cu] (), [Tp*WS3Cu3(?3-DMF)(CN)3Cu]·4aniline (·4aniline) and [Tp*WS3Cu3(?3-DMF)(CN)3Cu]·2(DMF)0.5 (·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 feature ?3-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 have identical chemical compositions in their main fragments but with distinctively different structural features, and are therefore topological isomers. Compound has a ladder-type structure in which the side rails contain alternately linked cluster cores and Cu(i) ions. Compound has a 2D (6,3) network with alternately arranged cluster cores and Cu(i) ions. Both and have 2D structures with 4·8(2) topology. In , 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 , the same 4-membered rings as those in are extended to equivalent rings via a cluster core-to-cluster and Cu-to-Cu arrangement. The hyperpolarizabilities (?) of the polymeric networks exhibit an enhancement of more than 10 times compared to their parent cluster, . PMID:25353691

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

2015-01-01

43

Solvent Production  

Technology Transfer Automated Retrieval System (TEKTRAN)

This article describes production of butanol [acetone-butanol-ethanol, (also called AB or ABE or solvent)] by fermentation using both traditional and current technologies. AB production from agricultural commodities such as corn and molasses was an important historical fermentation. Unfortunately,...

44

Structural insights into the coordination and extraction of Pb(II) by disulfonamide ligands derived from o-phenylenediamine.  

PubMed

The o-phenylenediamine-derived disulfonamide ligands 1 and 2 complex and efficiently extract Pb(II) from water into 1,2-dichloroethane via ion-exchange, in combination with 2,2'-bipyridine (97.5% and 95.0%, respectively, for 1:1 ligand-to-Pb ratios). The corresponding Pb(II)-sulfonamido binary complexes of ligands 1 and 2 (3 and 4, respectively), and ternary complexes with 2,2'-bipyridine (5 and 6, respectively), were isolated and characterized. (1)H NMR spectra of the organic phases after extraction show the formation of ternary Pb-sulfonamido-bipy complexes. X-ray characterization of 3, 4, and the ternary complex 5 consistently demonstrates four primary coordination sites and a stereochemically active lone pair on Pb. The X-ray structure of 3 shows a pseudo trigonal bipyramidal configuration on Pb, with the lone pair occupying one of the equatorial sites, and the formation of an unusual "hemidirected" coordination polymer via axial S=O-Pb coordination. The same axial S=O-Pb coordination pattern with two DMSO molecules is observed in the structure of 4.[2(CH(3))(2)SO)], thus rationalizing the high solubility of the binary complexes in strongly coordinating solvents. In contrast, the X-ray structure of the ternary complex 5 reveals a distorted four-coordinate configuration with only weak S=O-Pb coordination leading to dimer formation, thus explaining its higher solubility in weakly coordinating solvents. FT-IR spectroscopy confirms the X-ray data, since the ligand nu(S)(=)(O) stretching frequencies shift to lower values in the binary Pb(II)-sulfonamido complexes and are again altered upon formation of the ternary Pb(II)-sulfonamido-bipy complexes, as would be expected for 2,2'-bipy complexation and hindered S=O-Pb coordination. PMID:16241145

Alvarado, Robert J; Rosenberg, Jay M; Andreu, Aileen; Bryan, Jeffrey C; Chen, Wei-Zhong; Ren, Tong; Kavallieratos, Konstantinos

2005-10-31

45

Degreaser Reduces Solvent Loss  

NASA Technical Reports Server (NTRS)

Escape of solvent minimized by second cooling coil. Degreaser suppresses solvent-vapor loss through parts-basket dragout and air drafts. Within C02 blanket, convection repeatedly exposes C02/solvent mixture to cold spot created by C02 coil. Solvent vapor condenses, then runs down via through to cold tank. This small expenditure of C02 minimizes health and environmental hazards.

Du Fresne, E. R.

1985-01-01

46

Solvent wash solution  

DOEpatents

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.

Neace, J.C.

1984-03-13

47

Weak Deeply Virtual Compton Scattering  

SciTech Connect

We extend the analysis of the deeply virtual Compton scattering process to the weak interaction sector in the generalized Bjorken limit. The virtual Compton scattering amplitudes for the weak neutral and charged currents are calculated at the leading twist within the framework of the nonlocal light-cone expansion via coordinate space QCD string operators. Using a simple model, we estimate cross sections for neutrino scattering off the nucleon, relevant for future high intensity neutrino beam facilities.

Ales Psaker; Wolodymyr Melnitchouk; Anatoly Radyushkin

2007-03-01

48

Stoddard solvent poisoning  

MedlinePLUS

Stoddard solvent is a flammable, liquid chemical that smells like kerosene. Stoddard solvent poisoning occurs when someone ... swelling Nervous system: Burning sensations Convulsions Dizziness ... problems Nervousness Numbness in arms and legs Unconsciousness ...

49

Solvent selection for pharmaceuticals  

Microsoft Academic Search

The presence of solvents is essential in all steps of pharmaceutical processes (reaction, separation, and formulation). For toxicological reasons, drug manufacturers are increasingly required to minimize the number of solvents employed in pharmaceutical processes. In practice, the selection of solvents and antisolvents for pharmaceuticals mostly relies on experience, analogy and experimental testing.Our work aims to systematically investigate the solubility of

Petr Kolá?; Jun-Wei Shen; Akio Tsuboi; Takeshi Ishikawa

2002-01-01

50

Weak superconductivity  

SciTech Connect

This Proceedings consist of invited papers and contributions presented at the Fifth Czechoslovak Symposium on Weak Superconductivity (5CSSWS) held at Smolenice Castle from May 29 to June 2, 1989. This five-days meeting was organized by the Institute of Electrical Engineering, Electro-Physical Research Center, Slovak Academy of Sciences, Bratislava, in cooperation with the Institute of Measurement and Measuring Techniques, EPRC, SAS, Bratislava and the Institute of Physics, CSAS, in Prague. From the beginning the Czechoslovak activities in weak superconductivity were concerned with preparation and study of properties of weak links based on superconducting thin films of Pb, Nb, and Nb{sub 3}Sn, as well as bulk point contacts and rf SQUIDs for magnetometry. The possibility of application of superconducting weak links with tunnel and bridge junctions in measuring techniques, magnetometry, medicine, metrology, radiometry, etc., were studied. Some of these activities are still in progress. These Proceedings include contributions on the properties of tunnel junctions, electrodynamics of SQUIDs, computer simulation of interferometers, multi-channel magnetometry for biomagnetic applications, etc. The discovery of high T{sub c} superconductivity influenced strongly the topics of 5CSSWS. Most contributions of this volume are devoted to the preparation of high T{sub c} superconductor thin films by vacuum deposition techniques because of their dominant role in technology of cryoelectronic microcircuits. Further, results in the study of physical properties of high T{sub c} superconducting thin films by means of both dc and rf methods, tunnel and microcontact spectroscopy, are documented. Other contributions deal with preparation of rf SQUIDs, radiation detectors, etc.

Benacka, S.; Kedro, M.

1990-01-01

51

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

E-print Network

the phenol derivative (solute) in a mixed solvent of the benzene derivative and CCl4. The time dependence phenol in the mixed benzene/CCl4 solvent.9,10 A phenol molecule forms a weak hydrogen bond, sometimes

Fayer, Michael D.

52

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

PubMed

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

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

2014-10-11

53

Solvent extraction of molybdenum  

SciTech Connect

The equilibrium and the kinetics of the reaction of Mo(VI) with 8-hydroxyquinoline; 8-hydroxyquinaldine; KELEX 100; LIX63; and LIX65N were studied by solvent extraction. From the equilibrium studies it was concluded that in weakly acidic solution (pH 5 to 6) the complexation reaction requires four protons to convert molybdate into molybdenyl. The extractions constants for LIX63 and 8-hydroxyquinaldine, corrected for the side reaction of the ligand and metal, are 10/sup 16.43/ and 10/sup 14.40/, respectively. In the case of LIX65N, the plot of log(D) vs pH has a maximum at pH 1.0, which was explained qualitatively in terms of protonation of the ligand and molybdic acid at low pH. The extraction constant for the reaction of molybdic acid and the neutral ligand was estimated to be 100,000. The kinetics of extraction Mo (VI) with LIX63, 8-hydroxyquinoline, 8-hydroxyquinaldine, and Kelex 100 were studied in this work. In all cases, except 8-hydroxyquinoline, the rate-determining step of the reaction involves the formation of a 1:1 complex between the neutral ligand and several Mo(VI) species differing in the degree of protonation. The rate-determining step for the reaction of Mo(VI) with 8-hydroxyquinoline involves the formation of a 1:2 complex. The rate constant for the reaction of HMoO/sub 4/ with 8-hydroxyquinaldine is four orders of magnitude smaller than the corresponding value reported in the literature for 8-hydroxyquinoline. The slower reaction with 8-hydroxyquinaldine was attributed to the presence of the methyl group next to the nitrogen atom of the ligand which hinders its binding with molybdenum in the rate determining step of the reaction.

Trujillo, R.A.

1987-01-01

54

Geoboard - Coordinate  

NSDL National Science Digital Library

This interactive Java applet lets users explore the coordinate plane through the use of a Geoboard. The user places bands on the board where each peg is at an integer coordinate. Once a band has been placed, the applet outputs the perimeter and area of the shape or, if bands are placed as line segments, the applet outputs the distance and slope of the segment.

1999-01-01

55

Weak Energy: Form and Function  

E-print Network

The equation of motion for a time-independent 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 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) phase for cyclic evolutions. Pointed weak energy gauge transformations and the PFS 1-form are discussed and the relationship between the PFS 1-form and the AA connection 1-form is established.

Allen D. Parks

2013-04-09

56

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...

57

Alternative Green Solvents Project  

NASA Technical Reports Server (NTRS)

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.

Maloney, Phillip R.

2012-01-01

58

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

DOEpatents

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.

Nerad, Bruce A. (Longmont, CO); Krantz, William B. (Boulder, CO)

1988-01-01

59

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)....

60

Dendritic brushes under theta and poor solvent conditions  

NASA Astrophysics Data System (ADS)

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.

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

2013-07-01

61

Cleaning without chlorinated solvents  

SciTech Connect

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.

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

1994-12-31

62

LLNL solvent substitution  

SciTech Connect

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.

Benkovitch, M.G.

1992-12-01

63

Molecular tectonics: anion control of dimensionality and connectivity in meta-pyridyl appended tetramercaptotetrathiacalix[4]arene based silver coordination networks.  

PubMed

The combination of the same organic tecton 1, a meta-pyridyl appended tetramercaptotetrathiacalix[4]arene in 1,3-alternate conformation offering four pyridyl units and eight thioether groups, with three silver salts AgX (X = BF4(-), NO3(-) and SbF6(-)) leads, under identical conditions (concentration, temperature and solvent system), to the formation of different silver coordination networks. Both the connectivity and the dimensionality of the three silver coordination networks depend on the nature of the anion used as a counter ion. Whereas the weakly coordinating BF4(-) anion does not participate in the formation of the non-tubular 1D coordination network, the coordinating NO3(-) anion is bound to the metal cation and this leads to the formation of a tubular 1D silver coordination network. In both cases, the eight S atoms of the tecton 1 do not take part in the binding of the cation. In marked contrast, when the SbF6(-) anion is used as a counter ion, the organic tecton 1 behaves as a tetrakismonodentate through its four meta-pyridyl moieties and as a bischelating unit of the SCCS type leading thus to the formation of a porous 3D diamondoid-type network. PMID:24132039

Ovsyannikov, A; Ferlay, S; Solovieva, S E; Antipin, I S; Konovalov, A I; Kyritsakas, N; Hosseini, M W

2014-01-01

64

Practical Approaches to Green Solvents  

NASA Astrophysics Data System (ADS)

Solvents are widely used in commercial manufacturing and service industries. Despite abundant precaution, they inevitably contaminate our air, land, and water because they are difficult to contain and recycle. Researchers have therefore focused on reducing solvent use through the development of solvent-free processes and more efficient recycling protocols. However, these approaches have their limitations, necessitating a pollution prevention approach and the search for environmentally benign solvent alternatives. This report highlights opportunities for the practical implementation of such green solvents.

DeSimone, Joseph M.

2002-08-01

65

Safe battery solvents  

DOEpatents

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.

Harrup, Mason K. (Idaho Falls, ID); Delmastro, Joseph R. (Idaho Falls, ID); Stewart, Frederick F. (Idaho Falls, ID); Luther, Thomas A. (Idaho Falls, ID)

2007-10-23

66

Solvent resistant copolyimide  

NASA Technical Reports Server (NTRS)

A solvent resistant copolyimide was prepared by reacting 4,4'-oxydiphthalic anhydride with a diaimine blend comprising, based on the total amount of the diamine blend, about 75 to 90 mole percent of 3,4'-oxydianiline and about 10 to 25 mole percent p-phenylene diamine. The solvent resistant copolyimide had a higher glass transition temperature when cured at 350.degree. , 371.degree. and 400.degree. C. than LaRC.TM.-IA. The composite prepared from the copolyimide had similar mechanical properties to LaRC.TM.-IA. Films prepared from the copolyimide were resistant to immediate breakage when exposed to solvents such as dimethylacetamide and chloroform. The adhesive properties of the copolyimide were maintained even after testing at 23.degree., 150.degree., 177.degree. and 204.degree. C.

Chang, Alice C. (Inventor); St. Clair, Terry L. (Inventor)

1995-01-01

67

Halogenated solvent remediation  

DOEpatents

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.

Sorenson, Jr., Kent S. (Windsor, CO)

2008-11-11

68

Nonadiabatic dynamics of photoinduced proton-coupled electron transfer: comparison of explicit and implicit solvent simulations.  

PubMed

Theoretical approaches for simulating the ultrafast dynamics of photoinduced proton-coupled electron transfer (PCET) reactions in solution are developed and applied to a series of model systems. These processes are simulated by propagating nonadiabatic surface hopping trajectories on electron-proton vibronic surfaces that depend on the solute and solvent nuclear coordinates. The PCET system is represented by a four-state empirical valence bond model, and the solvent is treated either as explicit solvent molecules or as a dielectric continuum, in which case the solvent dynamics is described in terms of two collective solvent coordinates corresponding to the energy gaps associated with electron and proton transfer. The explicit solvent simulations reveal two distinct solvent relaxation time scales, where the faster time scale relaxation corresponds to librational motions of solvent molecules in the first solvation shell, and the slower time scale relaxation corresponds to the bulk solvent dielectric response. The charge transfer dynamics is strongly coupled to both the fast and slow time scale solvent dynamics. The dynamical multistate continuum theory is extended to include the effects of two solvent relaxation time scales, and the resulting coupled generalized Langevin equations depend on parameters that can be extracted from equilibrium molecular dynamics simulations. The implicit and explicit solvent approaches lead to qualitatively similar charge transfer and solvent dynamics for model PCET systems, suggesting that the implicit solvent treatment captures the essential elements of the nonequilibrium solvent dynamics for many systems. A combination of implicit and explicit solvent approaches will enable the investigation of photoinduced PCET processes in a variety of condensed phase systems. PMID:22651684

Auer, Benjamin; Soudackov, Alexander V; Hammes-Schiffer, Sharon

2012-07-01

69

Effect of solvent on diffusion: probing with nonpolar solutes.  

PubMed

Limiting mutual diffusion coefficients of carbon tetrachloride in methanol and of benzene, toluene, naphthalene, and biphenyl in cyclohexane as well as in ethanol at different temperatures are reported. These new data, together with literature diffusivities for the same probe solutes and for solute mesitylene in various solvents, are utilized to elucidate the effect of solvent on diffusion. Here, the data are consistent with our recent findings [J. Chem. Phys. 2013, 138, 224503] on the effects of free volume fraction, molar density, molecular mass, and fractional viscosity of solvent on diffusion. The results in this study show that the relation developed previously for solvent dependence of diffusion of disc-shaped solutes is also valid for spherical carbon tetrachloride. It is further found in this investigation that diffusivities are weakly dependent on a solvent's dielectric constant. A relation that includes the dielectric effect of solvent is demonstrated to be capable of describing the solvent dependence of diffusion of the nonpolar solutes of different shapes and sizes in this work to within an average deviation of ±2.7%. Comparisons with other diffusion models reveal that the newly developed relation is more accurate for representing the effect of solvent on diffusion. An expression for Zwanzig's "effective hydrodynamic radius" is also presented. PMID:25162797

Chan, T C; Lee, Irene; Chan, K S

2014-09-18

70

Unusual metal coordination chemistry from an amino-amide derivative of 4-nitrophenol, a surprising ligand.  

PubMed

The simple ligand N-(2-aminoethyl)-2-hydroxy-5-nitrobenzamide () exhibits several coordination modes depending on the reaction conditions, acting as a zwitterion on its own or being ionic in the presence of acid and depending on the concentration of metal present in a reaction, it can coordinate to the metal in either a 1:1 or a 1:2 metal:ligand mode. Furthermore, the role of solvent plays an important role in these complexation reactions with both four and six coordinate copper complexes being obtained using water as solvent but only six coordinate copper complexes obtained using acetonitrile as solvent. PMID:19789795

McGinley, John; McKee, Vickie; Toftlund, Hans; Walsh, John M D

2009-10-21

71

Femtosecond Infrared Study of the Dynamics of Solvation and Solvent Caging  

E-print Network

experimentally with 300-fs time resolution in the reactive, strongly coordinating CCl4 solution and in the inert in CCl4, 50 and 500 ps. The recombination dynamics are discussed in terms of solvent caging in which

Harris, Charles B.

72

ENGINEERING BULLETIN: SOLVENT EXTRACTION  

EPA Science Inventory

Solvent extraction does not destroy hazardous contaminants, but is a means of separating those contaminants from soils, sludges, and sediments, thereby reducing the volume of the hazardous material that must be treated. enerally it is used as one in a series of unit operations an...

73

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...

74

SOLVENT EXTRACTION TREATMENT  

EPA Science Inventory

Solvent extraction does not destroy wastes, but is a means of separating hazardous contaminants from soils, sludges, and sediments, thereby reducing the volume of the hazardous waste that must be treated. enerally it is used as one ina series of unit operations, and can reduce th...

75

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...

76

On Weakly Coherent Rings  

Microsoft Academic Search

In this paper, we define weakly coherent rings, and examine the transfer of these rings to homomorphic image, trivial ring extension, localization, and direct product. These results provide examples of weakly coherent rings that are not coherent rings. We show that the class of weakly coherent rings is not stable by localization. Also, we show that the class of weakly

Chahrazade Bakkari; Najib Mahdou

2010-01-01

77

Solvent dewaxing of lubricating oils  

SciTech Connect

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.

Sequeira, A. Jr.

1991-04-09

78

Lorentz Microscopy of Weak Magnetic Flux Inhomogeneities  

Microsoft Academic Search

The potential of Lorentz microscopy to give quantitative information about weak magnetic field inhomogeneities can be exploited fully only if the classical approximation to the electron contrast is abandoned in favor of the wave mechanical reality. The inhomogeneities cause coordinate dependent phase shifts ?&phgr;m in the coherent electron wavefunction which can be detected in principle by any electron optical method

D. Wohlleben

1968-01-01

79

Solvent substitution for electronic products  

SciTech Connect

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.

Benkovich, M.K.

1992-01-01

80

Colorimetric solvent indicators based on Nafion membranes incorporating nickel(II)-chelate complexes.  

PubMed

To develop solvent-recognition films, Nafion membranes incorporating cationic nickel-chelate complexes, that is, [Ni(L(1))(L(2))](+) (HL(1) = acetylacetone, 2,2,6,6-tetramethyl-3,5-heptanedione; L(2) = N,N-diethylethylenediamine, N-butyl-N,N',N'-trimethylethylenediamine), were prepared. Immersion of the films in various solvents effected the color changes varying from red to pale blue green depending on the donor number of the solvents. The color change is based on an equilibrium shift between square-planar and solvent-coordinated octahedral geometries of the cations. The degree of the color change depended on the affinity of the incorporated complex to the solvent molecules. The films were robust and exhibited a reversible solvent response. The films exhibited thermochromism when a small amount of appropriate solvents were incorporated and changed from pale blue green at low temperatures to red at high temperatures. PMID:25308167

Hosokawa, Hitoshi; Funasako, Yusuke; Mochida, Tomoyuki

2014-11-10

81

Solvent Immersion Imprint Lithography  

SciTech Connect

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.

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

2014-06-21

82

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

PubMed

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. PMID:22950803

Krakowiak, Joanna; Lundberg, Daniel; Persson, Ingmar

2012-09-17

83

Meridional vs. facial coordination geometries of a dipodal ligand framework featuring a secondary coordination sphere.  

PubMed

The synthesis of a novel dipodal ligand framework, H2[(Me)N(pi(Cy))2], is summarized. Upon metalation with MCl2 salts (M = Fe, Cu), the ligand undergoes a conformational change, resulting in the formation of a trigonal bipyramidal metal center with a pseudoplanar, meridionally-bound ligand framework. This tautomerization positions pendant amines in the metal's secondary coordination sphere. Metalation with M(OTf)2 in coordinating solvent yields octahedral metal complexes, where two solvent molecules bind in the apical positions with one outer sphere counter ion. Reactivity of these complexes, ((Me)N(afa(Cy))2)M(X)2 (X = Cl, OTf), with 2,2'-bypyridine results in ligand reorganization, yielding a facial coordination geometry of the dipodal framework. The described complexes have been characterized by (1)H NMR, EPR, IR, Mössbauer and electronic absorption spectroscopies as well as X-ray crystallography. PMID:25325404

Matson, Ellen M; Gordon, Zachary; Lin, Benjamin; Nilges, Mark J; Fout, Alison R

2014-12-01

84

On Weakly Coherent Rings  

E-print Network

In this paper, we define weakly coherent rings, and examine the transfer of these rings to homomorphic image, trivial ring extension, localization, and direct product. These results provide examples of weakly coherent rings that are not coherent rings. We show that the class of weakly coherent rings is not stable by localization. Also, we show that the class of weakly coherent rings and the class of strongly 2-coherent rings are not comparable.

Bakkari, Chahrazade

2010-01-01

85

Hyperconjugation-mediated solvent effects in phosphoanhydride bonds  

PubMed Central

Density functional theory and Natural Bond Orbital analysis are used to explore the impact of solvent on hyperconjugation in methyl triphosphate, a model for “energy rich” phosphoanhydride bonds, such as found in ATP. As expected, dihedral rotation of a hydroxyl group vicinal to the phosphoanhydride bond reveals that the conformational dependence of the anomeric effect involves modulation of the orbital overlap between the donor and acceptor orbitals. However, a conformational independence was observed in the rotation of a solvent hydrogen bond. As one lone pair orbital rotates away from an optimal anti-periplanar orientation, the overall magnitude of the anomeric effect is compensated approximately by the other lone pair as it becomes more anti-periplanar. Furthermore, solvent modulation of the anomeric effect is not restricted to the anti-periplanar lone pair; hydrogen bonds involving gauche lone pairs also affect the anomeric interaction and the strength of the phosphoanhydride bond. Both gauche and anti solvent hydrogen bonds lengthen non-bridging O—P bonds, increasing the distance between donor and acceptor orbitals, and decreasing orbital overlap which leads to a reduction of the anomeric effect. Solvent effects are additive with greater reduction in the anomeric effect upon increasing water coordination. By controlling the coordination environment of substrates in an active site, kinases, phosphatases and other enzymes important in metabolism and signaling, may have the potential to modulate the stability of individual phosphoanhydride bonds through stereoelectronic effects. PMID:23009395

Summerton, Jean C.; Evanseck, Jeffrey D.; Chapman, Michael S.

2012-01-01

86

Hyperconjugation-mediated solvent effects in phosphoanhydride bonds.  

PubMed

Density functional theory and natural bond orbital analysis are used to explore the impact of solvent on hyperconjugation in methyl triphosphate, a model for "energy rich" phosphoanhydride bonds, such as found in ATP. As expected, dihedral rotation of a hydroxyl group vicinal to the phosphoanhydride bond reveals that the conformational dependence of the anomeric effect involves modulation of the orbital overlap between the donor and acceptor orbitals. However, a conformational independence was observed in the rotation of a solvent hydrogen bond. As one lone pair orbital rotates away from an optimal antiperiplanar orientation, the overall magnitude of the anomeric effect is compensated approximately by the other lone pair as it becomes more antiperiplanar. Furthermore, solvent modulation of the anomeric effect is not restricted to the antiperiplanar lone pair; hydrogen bonds involving gauche lone pairs also affect the anomeric interaction and the strength of the phosphoanhydride bond. Both gauche and anti solvent hydrogen bonds lengthen nonbridging O-P bonds, increasing the distance between donor and acceptor orbitals and decreasing orbital overlap, which leads to a reduction of the anomeric effect. Solvent effects are additive with greater reduction in the anomeric effect upon increasing water coordination. By controlling the coordination environment of substrates in an active site, kinases, phosphatases, and other enzymes important in metabolism and signaling may have the potential to modulate the stability of individual phosphoanhydride bonds through stereoelectronic effects. PMID:23009395

Summerton, Jean C; Evanseck, Jeffrey D; Chapman, Michael S

2012-10-18

87

A thermodynamic study of selective solvation in solvent mixtures.  

PubMed

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

Cabot, Rafel; Hunter, Christopher A

2010-04-21

88

Weakly sufficient quantum statistics  

E-print Network

Some aspects of weak sufficiency of quantum statistics are investigated. In particular, we give necessary and sufficient conditions for the existence of a weakly sufficient statistic for a given family of vector states, investigate the problem of its minimality, and find the relation between weak sufficiency and other notions of sufficiency employed so far.

Katarzyna Lubnauer; Andrzej ?uczak; Hanna Pods?dkowska

2009-11-23

89

Synesthesia: Strong and Weak  

Microsoft Academic Search

In this review, we distinguish strong and weak forms of synesthesia. Strong synesthesia is characterized by a vivid image in one sensory modality in response to stimulation in another one. Weak synesthesia is characterized by cross-sensory correspondences expressed through language, perceptual similarity, and perceptual interactions during information processing. Despite important phenomenological dissimilarities between strong and weak synesthesia, we maintain that

Gail Martino; Lawrence E. Marks

2001-01-01

90

Focus Sensitive Coordination  

E-print Network

This thesis investigates the role of the Focus Sensitive Operators (FSOs) even and also when found inside of a coordination. Coordinations of this form are called Focus Sensitive Coordinations (FSC) and include or even, ...

Hulsey, Sarah McNearney

2008-01-01

91

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

SciTech Connect

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.

Delmau, Laetitia Helene [ORNL; Moyer, Bruce A [ORNL

2012-12-01

92

Optimized coordinates in vibrational coupled cluster calculations  

SciTech Connect

The use of variationally optimized coordinates, which minimize the vibrational self-consistent field (VSCF) ground state energy with respect to orthogonal transformations of the coordinates, has recently been shown to improve the convergence of vibrational configuration interaction (VCI) towards the exact full VCI [K. Yagi, M. Keçeli, and S. Hirata, J. Chem. Phys. 137, 204118 (2012)]. The present paper proposes an incorporation of optimized coordinates into the vibrational coupled cluster (VCC), which has in the past been shown to outperform VCI in approximate calculations where similar restricted state spaces are employed in VCI and VCC. An embarrassingly parallel algorithm for variational optimization of coordinates for VSCF is implemented and the resulting coordinates and potentials are introduced into a VCC program. The performance of VCC in optimized coordinates (denoted oc-VCC) is examined through pilot applications to water, formaldehyde, and a series of water clusters (dimer, trimer, and hexamer) by comparing the calculated vibrational energy levels with those of the conventional VCC in normal coordinates and VCI in optimized coordinates. For water clusters, in particular, oc-VCC is found to gain orders of magnitude improvement in the accuracy, exemplifying that the combination of optimized coordinates localized to each monomer with the size-extensive VCC wave function provides a supreme description of systems consisting of weakly interacting sub-systems.

Thomsen, Bo; Christiansen, Ove [Department of Chemistry, University of Aarhus, DK-8000 Aarhus C (Denmark)] [Department of Chemistry, University of Aarhus, DK-8000 Aarhus C (Denmark); Yagi, Kiyoshi [Theoretical Molecular Science Laboratory and iTHES, RIKEN, Hirosawa 2-1, Saitama 351-0198 (Japan)] [Theoretical Molecular Science Laboratory and iTHES, RIKEN, Hirosawa 2-1, Saitama 351-0198 (Japan)

2014-04-21

93

Superconducting weak links  

Microsoft Academic Search

This review covers experimental results and theoretical ideas on the properties of superconducting weak links, i.e., weak electrical contacts between superconducting electrodes which exhibit direct (non-tunnel-type) conductivity. When the dimensions of such weak links are sufficiently small, the Josephson effect is observed in them, in other words, a single-valued and 2pi -periodic relationship exists between the supercurrent Is and the

K. K. Likharev

1979-01-01

94

Weak Gravitational Lensing  

E-print Network

This review forms the Weak Lensing part of the Saas-Fee Advanced Course on Gravitational Lensing. It describes the basicsm applications and results of weak lensing. Contents: (1) Introduction (2) The principles of weak gravitational lensing (3) Observational issues and challenges (4) Clusters of galaxies: Introduction, and strong lensing (5) Mass reconstructions from weak lensing (6) Cosmic shear -- lensing by the LSS (7) Large-scale structure lensing: results (8) The mass of, and associated with galaxies (9) Additional issues in cosmic shear (10) Concluding remarks.

Peter Schneider

2005-09-09

95

Let's Learn Coordinates  

NSDL National Science Digital Library

Locate the Aliens or Help the Robot by understanding the four quadrants and the coordinates. Locate the Aliens By understanding the coordinates and quadrants, find the aliens. Direct the Robot Through the Maze Use your quadrant and coordinate knowledge to guide the Robot. Billy Bug s Quest for Grub Help Billy get to the right coordinates to feed. ...

Clark, Mr

2012-10-31

96

Supercritical multicomponent solvent coal extraction  

NASA Technical Reports Server (NTRS)

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.

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

1983-01-01

97

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...

98

Solvent degradation products in nuclear fuel processing solvents  

SciTech Connect

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.

Shook, H.E. Jr.

1988-06-01

99

A coordination framework for supply chain inventory alignment  

Microsoft Academic Search

Purpose – A traditional supply chain, all too often, is a sequence of weakly connected activities both within and outside the organization and leads to many misalignments. Tackling this inherent lack of coordination is a major value creation opportunity for supply chain managers. This paper aims to present a coordination framework, called ASCEND, to align the inventory decisions in decentralized

Rajesh Piplani; Yonghui Fu

2005-01-01

100

Reaction coordinates for electron transfer reactions  

SciTech Connect

The polarization fluctuation and energy gap formulations of the reaction coordinate for outer sphere electron transfer are linearly related to the constant energy constraint Lagrangian multiplier m in Marcus' theory of electron transfer. The quadratic dependence of the free energies of the reactant and product intermediates on m and m+1, respectively, leads to similar dependence of the free energies on the reaction coordinates and to the same dependence of the activation energy on the reorganization energy and the standard reaction free energy. Within the approximations of a continuum model of the solvent and linear response of the longitudinal polarization to the electric field in Marcus' theory, both formulations of the reaction coordinate are expected to lead to the same results.

Rasaiah, Jayendran C. [Department of Chemistry, University of Maine, Orono, Maine 04469 (United States); Zhu Jianjun [Department of Chemistry, State University of New York, Stonybrook, New York 11790 (United States) and Department of Chemistry, Henan Normal University, Xinxiang, Henan (China)

2008-12-07

101

Solvent effect on acid salt of dichloroacetic acid containing short and asymmetric OH…O bond  

NASA Astrophysics Data System (ADS)

The IR and 1H NMR spectra are reported for tetra-n-butylammonium bis-dichloroacetate in five dry aprotic solvents of different polarity (?=2.27 - 64.4) and basicity (DN= 0.1 - 15.1). Both the integrated intensity (A) and the centre of gravity ( overline?) of continuous absorption show weak dependence upon solvent used. The chemical shift (?) depends on the proton acceptor properties of solvents and is consistent with an equilibrium (BU) 4NA + AH ? (BU) 4N(AHA). The weak dependence of A and overline? upon the solvent polarity is consistent with the single minimum energy surface postulated in the literature for the strong OHO bonds.

Dega-Szafran, Z.; Szafran, M.

1986-03-01

102

Divalent Cu, Cd, and Pb Biosorption in Mixed Solvents  

PubMed Central

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. ??COO values (59–69 cm?1) confirmed bidentate metal coordination to carboxylate ligands. The value of ?asCOO 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

Al-Qunaibit, M. H.

2009-01-01

103

Uranyl-oxo coordination directed by non-covalent interactions.  

PubMed

Directed coordination of weakly Lewis acidic K(+) ions to weakly Lewis basic uranyl oxo ligands is accomplished through non-covalent cation-? and cation-F interactions for the first time. Comparison of a family of structurally related diarylamide ligands highlights the role that the cation-? and cation-F interactions play in guiding coordination. Cation binding to uranyl is demonstrated in the solid state and in solution, providing the shortest reported crystallographic uranyl-oxo to potassium distance. UV-Vis, TD-DFT calculations, and electrochemical measurements show that cation coordination directly impacts the electronics at the uranium(vi) cation. PMID:24894554

Lewis, Andrew J; Yin, Haolin; Carroll, Patrick J; Schelter, Eric J

2014-07-28

104

Fission product solvent extraction  

SciTech Connect

Two main objectives concerning removal of fission products from high-level tank wastes will be accomplished in this project. The first objective entails the development of an acid-side Cs solvent-extraction (SX) process applicable to remediation of the sodium-bearing waste (SBW) and dissolved calcine waste (DCW) at INEEL. The second objective is to develop alkaline-side SX processes for the combined removal of Tc, Cs, and possibly Sr and for individual separation of Tc (alone or together with Sr) and Cs. These alkaline-side processes apply to tank wastes stored at Hanford, Savannah River, and Oak Ridge. This work exploits the useful properties of crown ethers and calixarenes and has shown that such compounds may be economically adapted to practical processing conditions. Potential benefits for both acid- and alkaline-side processing include order-of-magnitude concentration factors, high rejection of bulk sodium and potassium salts, and stripping with dilute (typically 10 mM) nitric acid. These benefits minimize the subsequent burden on the very expensive vitrification and storage of the high-activity waste. In the case of the SRTALK process for Tc extraction as pertechnetate anion from alkaline waste, such benefits have now been proven at the scale of a 12-stage flowsheet tested in 2-cm centrifugal contactors with a Hanford supernatant waste simulant. SRTALK employs a crown ether in a TBP-modified aliphatic kerosene diluent, is economically competitive with other applicable separation processes being considered, and has been successfully tested in batch extraction of actual Hanford double-shell slurry feed (DSSF).

Moyer, B.A.; Bonnesen, P.V.; Sachleben, R.A. [and others

1998-02-01

105

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

SciTech Connect

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 systems.

Schwerdtfeger, Christine A.; Soudackov, Alexander V.; Hammes-Schiffer, Sharon, E-mail: shs3@illinois.edu [Department of Chemistry, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue, Urbana, Illinois 61801 (United States)] [Department of Chemistry, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue, Urbana, Illinois 61801 (United States)

2014-01-21

106

Hand Eye Coordination  

E-print Network

This paper describes a simple method of converting visual coordinates to arm coordinates which does not require knowledge of the position of the camera(s). Comparisons are made to other methods and two camera, three ...

Speckert, Glen

107

RESIDUAL RISK ASSESSMENT: HALOGENATED SOLVENTS  

EPA Science Inventory

This source category previously subjected to a technology-based standard will be examined to determine if health or ecological risks are significant enough to warrant further regulation for Halogenated Solvent Degreasing Facilities. These assessments utilize existing models and d...

108

SAGE--SOLVENT ALTERNATIVES GUIDE  

EPA Science Inventory

SAGE is a comprehensive guide designed to provide pollution prevention information on solvent and process alternatives for parts cleaning and degreasing. SAGE does not recommend any ozone depleting chemicals. SAGE was developed by the Surface Cleaning Program at Research Triang...

109

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 ...

110

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

PubMed Central

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

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

2013-01-01

111

Organic solvents for bioorganic synthesis  

Microsoft Academic Search

The influence of solvents on enzymatic activity and stability was investigated. As a model reaction the a-chymotrypsin-catalyzed esterification of N-acetyl-l-phenylalanine with ethanol was used. The enzyme was adsorbed on porous glass beads and used in various solvents. Small amounts of water were added to increase the enzymatic activity. These enzyme preparations obeyed. Michaelis-Menten kinetics. Km,app decreased slightly with the log

Mats Reslow; Patrick Adlercreutz; Bo Mattiasson

1987-01-01

112

Processing Coordination Ambiguity  

ERIC Educational Resources Information Center

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…

Engelhardt, Paul E.; Ferreira, Fernanda

2010-01-01

113

Solvent/Non-Solvent Sintering To Make Microsphere Scaffolds  

NASA Technical Reports Server (NTRS)

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.

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

2011-01-01

114

Gravitational anomaly and Hawking radiation near a weakly isolated horizon  

SciTech Connect

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.

Wu Xiaoning [Institute of Mathematics, Academy of Mathematics and Systems Science, Chinese Academy of Sciences, P.O. Box 2734, Beijing, 100080 (China); Kavli Institute for Theoretical Physics China at the Chinese Academy of Sciences (KITPC-CAS), P.O. Box 2732, Beijing, 100080 (China); Huang Chaoguang [Institute of High Energy Physics, Chinese Academy of Sciences, P.O. Box 918(4), Beijing, 100049 (China); Kavli Institute for Theoretical Physics China at the Chinese Academy of Sciences (KITPC-CAS), P.O. Box 2732, Beijing, 100080 (China); Sun Jiarui [Institute of High Energy Physics, Chinese Academy of Sciences, P.O. Box 918(4), Beijing, 100049 (China); Graduate School of Chinese Academy of Sciences, Beijing, 100049 (China)

2008-06-15

115

Emergent Soft Monopole Modes in Weakly-Bound Deformed Nuclei  

E-print Network

Based on the Hartree-Fock-Bogoliubov solutions in large deformed coordinate spaces, the finite amplitude method for quasiparticle random phase approximation (FAM-QRPA) has been implemented, providing a suitable approach to probe 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.

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

2014-11-13

116

Movement coordination during conversation.  

PubMed

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

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

2014-01-01

117

Coal liquefaction process with enhanced process solvent  

DOEpatents

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.

Givens, Edwin N. (Bethlehem, PA); Kang, Dohee (Macungie, PA)

1984-01-01

118

Aspects of dihydrogen coordination chemistry relevant to reactivity in aqueous solution  

Microsoft Academic Search

The aqueous coordination chemistry of dihydrogen has potential applications in inorganic biomimicry, chemoselective hydrogenation catalysis, and green chemistry. However, experimental and mechanistic studies that explore the aqueous behavior of these complexes are virtually unknown. This review identifies the motivation for studying aqueous dihydrogen coordination complexes by providing a summary of reactions that involve a dihydrogen ligand in highly polar solvents.

Nathaniel K. Szymczak; David R. Tyler

2008-01-01

119

Seminar publication: Solvent waste reduction alternatives  

SciTech Connect

;Contents: Land and Liquid Disposal Bans; Title III SARA - The Community`s Right to Know; Solvent Waste Burning Regulations; Waste Minimization Liability Issues; Minimization of Process Equipment Cleaning Waste; Source Reduction - Parts Cleaning; Solvent Waste Minimization by the Coatings Industry; What to do with Hazardous Waste: Regulations, Management, and Disposal; Waste Reduction for Chlorinated Solvents Users; On-Site Reuse and Recycle of Solvents; Commercial (Off-Site) Solvent Reclamation; Making the Most of Bottoms and Residuals; Treatment: Solvent Wastestreams; Treatment of Spent Solvent Wastewaters: Focus on Changing Economics.

NONE

1989-09-01

120

Influence of binary swelling solvents: Mechanism of action  

SciTech Connect

Green and Larsen reported that the up-take of chlorobenzene by coal is dramatically increased if small amounts of a good swelling solvent like pyridine are added. In efforts to understand how a small amount (ppm) of a good swelling solvent can exert such a pronounced effect, we have used our newly developed EPR spin probe method to examine the structural changes in binary solvent swelled (up to 5% pyridine) Argonne Premium Coal Samples (APCS). Results to date show that 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 site; (4) disruption of stronger hydrogen bonds within the macromolecules which causes an opening of the structure. Less dramatic effects are observed when more than 5% pyridine is used.

Ding, R.; Tucker, D.; Kispert, L.D. [Univ. of Alabama, Tuscaloosa, AL (United States)

1995-12-31

121

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

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 counterions of uranyl or introducing extra anions. PMID:25629464

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

122

The coordinator and coordinator programming language (COPL)  

SciTech Connect

As parallel architectures become more specialized for specific purposes, a distributed system with a network of heterogeneous parallel architectures will be very effective in order to satisfy a variety of parallel computational needs. Because such a system may be both complex and diverse, we cannot expect a homogeneous operating system to take care of all the heterogeneity of the proposed network and the related massive parallelism. The coordinator is defined as a system layer between the operating system and applications, and a common homogeneous interface is provided for users through heterogeneous coordinator services built on heterogeneous operating system kernels which provide a basic set of functions. The coordinator is a hierarchical system which manages jobs/processes/processors and may be based on a variety of implementation strategies. A new concurrent programming language, COPL (COordinator Programming Language), suitable for programming hierarchical resource management systems, was designed as a vehicle to implement the coordinator. COPL can be used effectively for concurrent programming in a combination of shared-memory-based multiprocessing and distributed processing without shared memory.

Jung, Cul-Doo.

1988-01-01

123

Hulett's Enhanced Solvent Tension. An Alternative to Lewis' Diminished Solvent Activity  

Microsoft Academic Search

Hulett proposed in 1903 that solute enhances the tension in the cohesive forces between solvent molecules by an amount equal to the osmotic pressure of the solvent. He attributed all the colligative properties of the solution solvent to this enhanced solvent tension. In 1908 Lewis proposed that the altered state of the solvent in solution was due to a reduced

H. T. Hammel

1983-01-01

124

Weak bump quasars  

NASA Technical Reports Server (NTRS)

The recent emphasis on big bumps dominating the UV continuum of quasars has obscured the facts that bump properties vary widely and that there are objects in which no such component is evident. As part of a survey of quasar continuum spectra, a class of quasars is identified in which the optical-UV continuum big bump feature appears to be weak or absent, relative to both IR and X-ray. These weak bump quasars are otherwise normal objects and constitute a few percent of the quasar population.

Mcdowell, Jonathan C.; Elvis, Martin; Wilkes, Belinda J.; Willner, Steven P.; Oey, M. S.

1989-01-01

125

Solvent-regenerated activated carbon  

SciTech Connect

This report summarizes the results of a University/Industry research project, sponsored by the New York State Energy Research and Development Authority and Fluids Design Corporation. The research project studied the solvent regeneration of activated carbon. Activate carbon was used to remove trace organics from aqueous streams, then regenerated by desorbing the adsorbates with organic solvents. The project included a survey of the potential applications in New York State industries, fundamental research on the adsorption/desorption phenomena, and design of a full-scale process. The economics of the full-scale process were evaluated and compared to alternate available technologies. The result of this work is a versatile process with attractive economics. A wide range of adsorbates and solvents were found to be acceptable for this process. The design methodologies are developed and the techniques for evaluating a new application are delineated. 13 refs., 12 figs., 4 tabs.

McLaughlin, H. (Fluids Design Corp., Troy, NY (USA))

1988-07-01

126

Solvent sensitive polymer composite structures  

NASA Astrophysics Data System (ADS)

In this paper we describe a composite system based on polystyrene colloidal nanoparticles assembled and embedded in an elastomeric matrix (polymer colloidal crystal, PCC), in the specific we have designed a PCC structure which displays an iridescent green color that can be attributed to the photonic crystal effect. This effect has been exploited to create a chemical sensor, in fact optical measurements have evidenced that the composite structure presents a different optical response as a function of the solvent applied on the surface. In particular we have demonstrated that the PCC possess, for specific solvents: (i) high sensitivity, (ii) fast response (less than 1s), and (iii) reversibility of the signal change. Finally preliminary results on the PCC have shown that this system can be also used as optical writing substrate using a specific solvent as ink, moreover an erasing procedure is also reported and discussed.

Chiappini, A.; Armellini, C.; Carpentiero, A.; Minati, L.; Righini, G. C.; Ferrari, M.

2013-11-01

127

Weak Finsler structures and the Funk weak metric  

NASA Astrophysics Data System (ADS)

We discuss general notions of metrics and of Finsler structures which we call weak metrics and weak Finsler structures. Any convex domain carries a canonical weak Finsler structure, which we call its tautological weak Finsler structure. We compute distances in the tautological weak Finsler structure of a domain and we show that these are given by the so-called Funk weak metric. We conclude the paper with a discussion of geodesics, of metric balls and of convexity properties of the Funk weak metric.

Papadopoulos, Athanase; Troyanov, Marc

2009-04-01

128

Dynamical arrest of electron transfer in liquid crystalline solvents.  

PubMed

We argue that electron transfer reactions in slowly relaxing solvents proceed in the nonergodic regime, making the reaction activation barrier strongly dependent on the solvent dynamics. For typical dielectric relaxation times of polar nematics, electron transfer reactions in the subnanosecond time scale fall into nonergodic regime in which nuclear solvation energies entering the activation barrier are significantly lower than their thermodynamic values. The transition from isotropic to nematic phase results in weak discontinuities of the solvation energies at the transition point and the appearance of solvation anisotropy weakening with increasing solute size. The theory is applied to analyze experimental kinetic data for the electron transfer kinetics in the isotropic phase of 5CB liquid crystalline solvent. We predict that the energy gap law of electron transfer reactions in slowly relaxing solvents is characterized by regions of fast change of the rate at points where the reaction switches between the ergodic and nonergodic regimes. The dependence of the rate on the donor-acceptor separation may also be affected in a way of producing low values for the exponential falloff parameter. PMID:16805631

Kapko, Vitaliy; Matyushov, Dmitry V

2006-07-01

129

MICROBIOLOGY: Breathing with Chlorinated Solvents  

NSDL National Science Digital Library

Access to the article is free, however registration and sign-in are required: Chlorinated solvents, the carcinogenic agents that permeate the air in your dry cleaners, have accumulated in the groundwater because microorganisms in the soil do not break them down. Now Maymó-Gatell et al. have isolated the first bacterium that can metabolize trichloroethylene and perchloroethylene to the harmless compound ethene. Identification of the bacterium will potentially allow manipulation of the conditions underground to facilitate the natural destruction of chlorinated solvents.

Perry L. McCarty (Stanford University; Department of Civil Engineering)

1997-06-06

130

Weak Boundary Layers in Styrene-Butadiene Rubber  

Microsoft Academic Search

In this paper two kinds of weak boundary layers (WBL) in synthetic vulcanized styrene-butadiene rubber are described.i) WBL produced by the presence of antiadhesion compounds of the rubber formulation (zinc stearate, microcrystalline paraffin wax). These WBL cannot be effectively removed by solvent wiping, whether followed by washing with an ethanol\\/water mix or not. Although this treatment allowed a significant removal

M. M. Pastor-Blas; M. S. Sánchez-Adsuar; J. M. Martín-Martínez

1995-01-01

131

The Weak Mixing Matrix  

NASA Astrophysics Data System (ADS)

We show that the Weak Mixing Matrix, ( *20c Uud & Uus & Uub Ucd & Ucs & Ucb Utd & Uts & Utb ) , is not equal to the product of rotations, and in particular, it is not equal to the KM, or the PDG Matrices. At most, we may find an approximating matrix for the Weak Mixing Matrix that is based on the rotation matrices. We show that one such approximating matrix for the Real part of the Weak Mixing Matrix is ( *20c ?C?C^3 & ?C?C^3 & ^3 ?C?C^2 - ?C?C^2 & ?C?C^2 & ^2 ?C - ?C^3 ?C & - ?C?C^3 ^2 ?C & ?C^2 ?C^3 ), where ?C is the Cabbibo angle. The approximating matrix depends on ?C alone, and predicts the Real part of the Weak Mixing Matrix to a high degree of accuracy. We establish, with a Chi-Squared Goodness-of- Fitness-Test, that our approximating matrix can be used with extremely high level of statistical confidence.

Dannon, Vic; Levine, Robert

2009-10-01

132

Generic weak isolated horizons  

NASA Astrophysics Data System (ADS)

Weak isolated horizon boundary conditions have been relaxed supposedly to their weakest form so that both zeroth and first laws of black hole mechanics hold. This makes the formulation more amenable for applications in both analytic and numerical relativities. It also unifies the phase spaces of non-extremal and extremal black holes.

Chatterjee, Ayan; Ghosh, Amit

2006-12-01

133

Quantum weak turbulence  

SciTech Connect

The present manuscript dealing with large occupation of states of a quantum system, extends the study to the case of quantum weak turbulence. The quasiparticle spectrum, calculated for such a system, using a Green's function approach, establishes the dissipative and inertial regimes, hence a Kolmogorov type of picture.

Sanyal, Devashish [Department of Theoretical Physics, Indian Association for the Cultivation of Science, Jadavpur, Calcutta 700032 (India)]. E-mail: tpds@mahendra.iacs.res.in; Sen, Siddhartha [School of Mathematics, Trinity College, Dublin 2 (Ireland)]. E-mail: sen@maths.tcd.ie

2006-06-15

134

Weak Radial Artery Pulse  

PubMed Central

We present an 11year-old boy with a weak right radial pulse, and describe the successful application of vascular ultrasound to identify the ulnar artery dominance and a thin right radial artery with below normal Doppler flow velocity that could explain the discrepancy. The implications of identifying this anomaly are discussed. PMID:22375269

Venugopalan, Poothirikovil; Sivakumar, Puthuval; Ardley, Robert G.; Oates, Crispian

2012-01-01

135

Automated Solvent Seaming of Large Polyimide Membranes  

NASA Technical Reports Server (NTRS)

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 the movement of the positioning table.

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

2006-01-01

136

Coordination complexity of parallel Lagrangian decomposition  

SciTech Connect

We present polylogarithmically-matching upper and lower bounds on the number of parallel iterations (coordination complexity) for two wide classes of Lagrangian decomposition methods for solving general block-angular convex programs to a fixed accuracy. The lower bounds hold for multicommodity flows and even with an all-powerful coordinator. Our near-optimal upper bounds are valid for two Lagrangian decomposition methods based on the classical logarithmic barrier and the exponential potential functions. The coordination step of either method can be implemented to run in almost linear sequential or logarithmic parallel time in the number of coupling constraints. The choice of which function or method to use depends upon a theoretical characterization of an instance as a weakly- or strongly-coupled problem. Some special cases, including multicommodity flows, and a sublinear-time randomized approximation algorithm for matrix games, will be discussed. We shall also summarize computational results for large minimum-cost multicommodity network flow problems.

Grigoriadis, M.; Khachiyan, L.

1994-12-31

137

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

PubMed Central

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 ?-helical and a ?-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

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

2013-01-01

138

Why are dimethyl sulfoxide and dimethyl sulfone such good solvents?  

PubMed

We have carried out B3PW91 and MP2-FC computational studies of dimethyl sulfoxide, (CH(3))(2)SO, and dimethyl sulfone, (CH(3))(2)SO(2). The objective was to establish quantitatively the basis for their high polarities and boiling points, and their strong solvent powers for a variety of solutes. Natural bond order analyses show that the sulfur-oxygen linkages are not double bonds, as widely believed, but rather are coordinate covalent single S(+)-->O(-) bonds. The calculated electrostatic potentials on the molecular surfaces reveal several strongly positive and negative sites (the former including sigma-holes on the sulfurs) through which a variety of simultaneous intermolecular electrostatic interactions can occur. A series of examples is given. In terms of these features the striking properties of dimethyl sulfoxide and dimethyl sulfone, their large dipole moments and dielectric constants, their high boiling points and why they are such good solvents, can readily be understood. PMID:18458968

Clark, Timothy; Murray, Jane S; Lane, Pat; Politzer, Peter

2008-08-01

139

Large-scale solvent driven actuation of polyelectrolyte multilayers based on modulation of dynamic secondary interactions.  

PubMed

Polyelectrolyte multilayers (PEMs), assembled from weak polyelectrolytes, have often been proposed for use as smart or responsive materials. However, such response to chemical stimuli has been limited to aqueous environments with variations in ionic strength or pH. In this work, a large in magnitude and reversible transition in both the swelling/shrinking and the viscoelastic behavior of branched polyethylenimine/poly(acrylic acid) multilayers was realized in response to exposure with various polar organic solvents (e.g., ethanol, dimethyl sulfoxide, and tetrahydrofuran). The swelling of the PEM decreases with an addition of organic content in the organic solvent/water mixture, and the film contracts without dissolution in pure organic solvent. This large response is due to both the change in dielectric constant of the medium surrounding the film as well as an increase in hydrophobic interactions within the film. The deswelling and shrinking behavior in organic solvent significantly enhances its elasticity, resulting in a stepwise transition from an initially liquid-like film swollen in pure water to a rigid solid in pure organic solvents. This unique and recoverable transition in the swelling/shrinking behaviors and the rheological performances of weak polyelectrolyte multilayer film in organic solvents is much larger than changes due to ionic strength or pH, and it enables large scale actuation of a freestanding PEM. The current study opens a critical pathway toward the development of smart artificial materials. PMID:25539141

Gu, Yuanqing; Huang, Xiayun; Wiener, Clinton G; Vogt, Bryan D; Zacharia, Nicole S

2015-01-28

140

NATURAL ATTENUATION OF CHLORINATED SOLVENTS  

EPA Science Inventory

The protocol will simply describe in detail, with references and illustrations, the approach currently used by staff of the SPRD to evaluate natural attenuation of chlorinated solvents in ground water. Staff of SPRD, and staff of the Air Force Center for environmental excellence...

141

Nanopapers for organic solvent nanofiltration.  

PubMed

Would it not be nice to have an organic solvent nanofiltration membrane made from renewable resources that can be manufactured as simply as producing paper? Here the production of nanofiltration membranes made from nanocellulose by applying a papermaking process is demonstrated. Manufacture of the nanopapers was enabled by inducing flocculation of nanofibrils upon addition of trivalent ions. PMID:24752201

Mautner, A; Lee, K-Y; Lahtinen, P; Hakalahti, M; Tammelin, T; Li, K; Bismarck, A

2014-06-01

142

Trifocal tensors for weak perspective and paraperspective projections  

Microsoft Academic Search

Trilinear relationships among the image point coordinates obtained by perspective projection of several feature points over three views have been investigated, and it has been shown that seven point correspondences are sufficient to determine the coefficients involved. We show that analogous trilinear relationships exist for the weak perspective and paraperspective projections, and that only four point correspondences are necessary for

Alfred M. Bruckstein; Robert J. Holt; Thomas S. Huang; Arun N. Netravali

2001-01-01

143

Heliospheric coordinate systems  

Microsoft Academic Search

This article gives an overview and reference to the most common coordinate systems currently used in space science. While coordinate systems used in near-Earth space physics have been described in previous work we extend that description to systems used for physical observations of the Sun and the planets and to systems based on spacecraft location. For all systems, we define

M. Fränz; D. Harper

2002-01-01

144

Social Postural Coordination  

ERIC Educational Resources Information Center

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…

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

2011-01-01

145

Weak Polarized Electron Scattering  

E-print Network

Scattering polarized electrons provides an important probe of the weak interactions. Precisely measuring the parity-violating left-right cross section asymmetry is the goal of a number of experiments recently completed or in progress. The experiments are challenging, since A_{LR} is small, typically between 10^(-4) and 10^(-8). By carefully choosing appropriate targets and kinematics, various pieces of the weak Lagrangian can be isolated, providing a search for physics beyond the Standard Model. For other choices, unique features of the strong interaction are studied, including the radius of the neutron density in heavy nuclei, charge symmetry violation, and higher twist terms. This article reviews the theory behind the experiments, as well as the general techniques used in the experimental program.

Jens Erler; Charles J. Horowitz; Sonny Mantry; Paul A. Souder

2014-04-07

146

Solution Phase Measurement of Both Weak Sigma and C-H---X- Hydrogen Bonding Interactions in Synthetic Anion Receptors  

SciTech Connect

A series of tripodal receptors preorganize electron-deficient aromatic rings to bind halides in organic solvents using weak sigma anion-to-arene interactions or C-H---X- hydrogen bonds. 1H NMR spectroscopy proves to be a powerful technique for quantifying binding in solution, and determining the interaction motifs, even in cases of weak binding.

Berryman, Mr. Orion B. [University of Oregon; Sather, Mr. Aaron C [University of Oregon; Hay, Benjamin [ORNL; Meisner, Mr. Jeffrey S. [University of Oregon; Johnson, Prof. Darren W. [University of Oregon

2008-01-01

147

Coordination sequences and coordination waves in matter  

SciTech Connect

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.

Rau, V. G., E-mail: vgrau@mail.ru; Pugaev, A. A.; Rau, T. F. [Vladimir State Pedagogical University (Russian Federation)

2006-01-15

148

Occupational exposure to organic solvents and breast cancer in women  

PubMed Central

Background Although studies in rodents suggest possible associations between exposure to organic solvents and breast cancer, the evidence in humans is limited. Methods We evaluated job histories of 2383 incident breast cancer cases diagnosed during 2000–2003, and 2502 controls who participated in a large population-based case-control study in Poland. Industrial hygienists reviewed occupational histories and developed exposure metrics for total organic solvents and benzene. Unconditional logistic regression analyses estimated odds ratios (ORs) and 95% confidence intervals (CIs) as the measure of association with breast cancer, controlling for breast cancer risk factors. Stratified analyses examined the potential modification by known breast cancer risk factors. Associations were also evaluated by estrogen (ER) and progesterone receptor (PR) status and by other clinical characteristics of the tumours using polytomous regression analyses. Results Women who ever worked at jobs with organic solvents exposure had a small, non-significant increase in breast cancer risk (OR=1.16; 95%CI 0.99 to 1.4). A significant association was present for ER and PR negative tumors (OR 1.40; 95% CI 1.1 to 1.8), but there was no association with tumors with both positive receptors (OR 0.97; 95% CI 0.8 to 1.2 (p-heterogeneity: 0.008)). We did not observe trends with increasing level of exposure. Known breast cancer risk factors did not modify the association with organic solvents and breast cancer risk. No association with breast cancer was found for benzene exposure (OR 1.00; 95% CI 0.8 to 1.3). Conclusion Our study provides weak evidence for a possible association between occupational exposure to organic solvents as a class and breast cancer risk. The association might be limited to hormone receptor negative tumors. PMID:19819862

Peplonska, Beata; Stewart, Patricia; Szeszenia-D?browska, Neonila; Lissowska, Jolanta; Brinton, Louise A.; Gromiec, Jan Piotr; Brzeznicki, Slawomir; Yang, Rose; Sherman, Mark; García-Closas, Montserrat; Blair, Aaron

2009-01-01

149

Dipolar correlations in structured solvents under nanoconfinement  

NASA Astrophysics Data System (ADS)

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.

Buyukdagli, Sahin; Blossey, Ralf

2014-06-01

150

Wash solvent reuse in paint production  

SciTech Connect

The project evaluated solvent used to clean paint manufacture equipment for its utility in production of subsequent batches of solvent-borne paint. Reusing wash solvent would reduce the amount of solvent disposed of as waste. The evaluation of this wash-solvent recovery technology was conducted by Battelle Memorial Institute for the Pollution Prevention Research Branch of the U.S. Environmental Protection Agency. The evaluation was conducted with the cooperation and assistance of Vanex Color, Inc. The product quality, waste reduction/pollution prevention, and economic impacts of this technology change, as it has been implemented by Vanex, were examined. Two batches of a solvent-borne alkyd house paint were prepared at Vanex--one batch made with 100%-new solvent and the other with 30%-wash solvent--and sampled for laboratory analysis at Battelle.

Parsons, A.B.; Heater, K.J.; Olfenbuttel, R.F.

1994-04-01

151

Neuropathy - Coordination Exam - Lower Extremities Sub-exam - Patient 7  

NSDL National Science Digital Library

This video demonstrates a coordination exam of the lower extremities. This 61-year-old man has had slowly progressive gait disturbance and weakness of his legs for 14 years. He has developed a limp in both legs, and his feet trip on objects and on uneven floor surfaces resulting in falls. Weakness and numbness of the legs is limiting his ability to walk. Viewing the video requires installation of the free QuickTime Plug-in.

Pearson, John C.

2009-01-02

152

Gradient Solvent Vapor Annealing of Thin Films  

Microsoft Academic Search

The development of block copolymer materials for emerging nanotechnologies requires an understanding of how surface energy\\/chemistry and annealing conditions affect thin film self-assembly. Specifically, in solvent vapor annealing (SVA), the use of solvent mixtures and the manipulation of solvent vapor concentration are promising approaches for obtaining a desired morphology or nanostructure orientation. We designed and fabricated solvent-resistant devices to produce

Julie Albert; Timothy Bogart; Ronald Lewis; Thomas Epps

2011-01-01

153

The Coordinate Plane  

NSDL National Science Digital Library

This is a set of three, one-page problems about how astronomers use coordinate systems. Learners will plot a constellation on a coordinate plane and/or plot the route of Mars Science Lab (MSL aka Curiosity) on the surface of Mars. Options are presented so that students may learn about the MSL mission through a NASA press release or about the coordinate plane by viewing a NASA eClips video [7 min.]. This activity is part of the Space Math multi-media modules that integrate NASA press releases, NASA archival video, and mathematics problems targeted at specific math standards commonly encountered in middle school.

2014-03-19

154

Firing of pulverized solvent refined coal  

DOEpatents

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.

Derbidge, T. Craig (Sunnyvale, CA); Mulholland, James A. (Chapel Hill, NC); Foster, Edward P. (Macungie, PA)

1986-01-01

155

Solvent-induced forces in protein folding  

SciTech Connect

The solvent-induced forces between various groups on the protein are examined. It is found that the intramolecular hydrophilic forces are likely to be the strongest forces mediated through the solvent. It is argued that these are probably the most important solvent-induced driving forces in the process of protein folding.

Ben-Naim, A. (Hebrew Univ., Jerusalem (Israel))

1990-08-23

156

Co(iii) protoporphyrin IX chloride in solution: spin-state and metal coordination revealed from resonant inelastic X-ray scattering and electronic structure calculations.  

PubMed

The local electronic structure of the cobalt centre-ion of Co(iii) protoporphyrin IX chloride dissolved in dimethyl sulfoxide (DMSO) liquid solution is studied by resonant inelastic X-ray scattering (RIXS) spectroscopy at the cobalt L-edge. The resulting cobalt 2p partial-fluorescence-yield (PFY) X-ray absorption (XA) spectrum, integrated from RIXS spectra, is simulated for various possible spin-states and coordination of the cobalt centre by using the newly developed density functional theory/restricted open shell single excitation configuration interaction (DFT/ROCIS) method. Comparison between experiment and calculation shows that the cobalt ion (3d(6) electronic configuration) adopts a low-spin state with all six 3d electrons paired, and the cobalt centre is either 5-coordinated by its natural ligands (one chloride ion and four nitrogen atoms), or 6-coordinated, when binding to an oxygen atom of a DMSO solvent molecule. Analysis of the measured RIXS spectra reveals weak 3d-3d electron correlation, and in addition a value of the local HOMO-LUMO gap at the Co sites is obtained. PMID:25529387

Atak, Kaan; Golnak, Ronny; Xiao, Jie; Pflüger, Mika; Brandenburg, Tim; Winter, Bernd; Aziz, Emad F

2015-02-01

157

Is Water a Universal Solvent for Life?  

NASA Technical Reports Server (NTRS)

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 of cellular boundary structures or protein folding. Strengths of electrostatic and hydrophobic interactions are similar and can be balanced over a wide range of temperatures, which considerably increases the repertoire of interactions that can be used to modulate biological functions. Some properties of water, e.g. its chemical activity against polymerization reactions, are considered as unfavorable to life. In actuality, this might be a favorable trait because life requires a balance between constructive and destructive processes. For example, molecules synthesized in response to specific conditions must be degraded once these conditions change. Otherwise regulation of biological processes would be virtually impossible. Water might not be the only liquid with favorable properties for supporting life. It has been proposed that formamide, which might be present elsewhere in the universe in sufficient quantities to warrant interest, could be a potential alternative to water for the origin of life. However, this will remain highly hypothetical until it is demonstrated in further studies on its physical, chemical and biological properties it is capable of mediating self-organization of matter and providing proper balance between different types of non-covalent interactions.

Pohorill, Andrew

2012-01-01

158

Weak Lensing and Cosmology  

E-print Network

We explore the dependence of weak lensing phenomena on the background cosmology. We first generalise the relation between $P_\\psi(\\omega)$, the angular power spectrum of the distortion, and the power spectrum of density fluctuations to non-flat cosmologies. We then compute $P_\\psi$ for various illustrative models. A useful cosmological discriminator is the growth of $P_\\psi$ with source redshift which is much stronger in low matter density models, and especially in $\\Lambda$-dominated models. With even crude redshift information (say from broad band colours) it should be possible to constrain the cosmological world model. The amplitude of $P_\\psi(\\omega)$ is also quite sensitive to the cosmology, but requires a reliable external normalisation for the mass fluctuations. If one normalises to galaxy clustering, with $M/L$ fixed by small-scale galaxy dynamics, then low density models predict a much stronger distortion. If, however, one normalises to large-scale bulk-flows, the predicted distortion for sources at redshifts $Z_s \\sim 1-3$ is rather insensitive to the background cosmology. The signals predicted here can be detected at a very high level of significance with a photometric survey covering say 10 square degrees, but sparse sampling is needed to avoid large sampling variance and we discuss the factors influencing the design of an optimum survey. Turning to weak lensing by clusters we find that for high lens redshifts ($Z_l\\simeq1$) the critical density is substantially reduced in $\\Lambda$ models, but that the ratio of the shear or convergence to the velocity dispersions or X-ray temperature of clusters is only very weakly dependent on the cosmology.

Nick Kaiser

1996-10-16

159

Weak Isolated Horizons  

SciTech Connect

Weak Isolated Horizon (WIH) is the most general definition of a black hole horizon so far i.e. WIH is defined through the weakest possible set of boundary conditions imposed on a generic null surface. We will also show that the laws of black hole mechanics can be derived for these horizons. In addition, the definition enables us to put the extremal and non-extremal black holes on the same phase-space so that one can make sense of extremal limit.

Chatterjee, Ayan [Theory Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata-700064 (India)

2007-10-03

160

Corrected geomagnetic pole coordinates  

Microsoft Academic Search

A new method for the accurate calculation of the corrected geomagnetic pole coordinates is developed. The results are compared with those obtained by previous methods, and maximum divergence was found to be approximately 1-deg.

Iu. L. Sverdlov; T. N. Khorkova

1982-01-01

161

Local Coordinates Model  

NSDL National Science Digital Library

The Local Coordinates model displays the position of a star in local (Altitude/Azimuth) coordinates. The horizon is shown along with the four cardinal directions (N, E, S, and W). The latitude of the observer is set at 35.5 degrees which sets the location of the north celestial pole (teal) relative to the northern horizon. The position of the star can be changed by using the Altitude and Azimuth sliders. The Local Coordinates model was created using the Easy Java Simulations (EJS) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_astronomy_Local Coordinates.jar file will run the program if Java is installed. EJS is a part of the Open Source Physics Project and is designed to make it easier to access, modify, and generate computer models.

Belloni, Mario; Timberlake, Todd

2010-01-02

162

HR COMMUNICATIONS Program Coordinator  

E-print Network

HR COMMUNICATIONS Program Coordinator 51518 9254 04 VACANT University Business Administrator II TECHNOLOGY/ HR DATA MANAGEMENT/ COMMUNICATIONS RECORDS BENEFITS TIME & LABOR EMPLOYEE DATA MANAGEMENT EMPLOYMENT FACILITIES SATELLITE OFFICE EMPLOYEE & LABOR RELATIONS Director, Admin Svcs 55607 9250A 07 VACANT

Ronquist, Fredrik

163

Coordination Mechanisms George Christodoulou  

E-print Network

Coordination Mechanisms George Christodoulou Elias Koutsoupias Akash Nanavati§ Abstract We of Athens. Email: elias@di.uoa.gr § Computer Science Department, University of California Los Angeles. Email

Koutsoupias, Elias

164

A Universe Without Weak Interactions  

E-print Network

Universe” 1 has big-bang nucleosynthesis, structure formation,Universe without weak interactions that undergoes BBN, matter domination, structure formation,universe without weak interactions is constructed that undergoes big-bang nucleosynthesis, matter domination, structure formation, and

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

2006-01-01

165

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)

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.

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

2006-11-01

166

Luminescent lanthanide coordination polymers  

SciTech Connect

One-dimensional lanthanide coordination polymers with the formula Ln(isonicotinate){sub 3}(H{sub 2}O){sub 2} (Ln = Ce, Pr, Nd, Sm, Eu, Tb; 1a-f) were synthesized by treating nitrate or perchlorate salts of Ln(III) with 4-pyridinecarboxaldehyde under hydro(solvo)thermal conditions. Single-crystal and powder X-ray diffraction studies indicate that these lanthanide coordination polymers adopt two different structures. While Ce(III), Pr(III), and Nd(III) complexes adopt a chain structure with alternating Ln-(carboxylate){sub 2}-Ln and Ln-(carboxylate){sub 4}-Ln linkages, Sm(III), Eu(III), and Tb(III) complexes have a doubly carboxylate-bridged infinite-chain structure with one chelating carboxylate group on each metal center. In both structures, the lanthanide centers also bind to two water molecules to yield an eight-coordinate, square antiprismatic geometry. The pyridine nitrogen atoms of the isonicotinate groups do not coordinate to the metal centers in these lanthanide(III) complexes; instead, they direct the formation of Ln(III) coordination polymers via hydrogen bonding with coordinated water molecules. Photoluminescence measurements show that Tb(isonicotinate){sub 3}(H{sub 2}O){sub 2} is highly emissive at room temperature with a quantum yield of {approximately}90%. These results indicate that highly luminescent lanthanide coordination polymers can be assembled using a combination of coordination and hydrogen bonds. Crystal data for 1a: monoclinic space group P2{sub 1}/c, a = 9.712(2) {angstrom}, b = 19.833(4) {angstrom}, c = 11.616(2) {angstrom}, {beta} = 111.89(3){degree}, Z = 4. Crystal data for 1f: monoclinic space group C2/c, a = 20.253(4) {angstrom}, b = 11.584(2) {angstrom}, c = 9.839(2) {angstrom}, {beta} = 115.64(3){degree}, Z = 8.

Ma, L.; Evans, O.R.; Foxman, B.M.; Lin, W.

1999-12-13

167

Equatorial Coordinates Model  

NSDL National Science Digital Library

The Equatorial Coordinates model displays the position of a star in equatorial (Right Ascension/Declination --- RA/Dec) coordinates. The horizon is shown along with the four cardinal directions (N, E, S, and W). The Latitude slider changes the latitude of the observer which is shown by the change in the (teal) celestial pole relative to the northern horizon. The position of the star can be changed by using the Right Ascension and Declination sliders. Once these coordinates are selected, pressing the play button will put the star, celestial grid, and the equatorial coordinates in motion to simulate the 23 hour and 56 minute motion of stars in the night sky. Equatorial Coordinates model is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_astronomy_EquatorialCoordinates.jar file will run the program if Java is installed. You can modify this simulation if you have EJS installed by right-clicking within the plot and selecting "Open EJS Model" from the pop-up menu item.

Belloni, Mario; Timberlake, Todd

2009-11-14

168

Batch extracting process using magneticparticle held solvents  

DOEpatents

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.

Nunez, Luis (Elmhurst, IL); Vandergrift, George F. (Bolingbrook, IL)

1995-01-01

169

Weak lensing and dark energy  

Microsoft Academic Search

We study the power of upcoming weak lensing surveys to probe dark energy. Dark energy modifies the distance-redshift relation as well as the matter power spectrum, both of which affect the weak lensing convergence power spectrum. Some dark-energy models predict additional clustering on very large scales, but this probably cannot be detected by weak lensing alone due to cosmic variance.

Dragan Huterer

2002-01-01

170

On Weakly Finite Conductor Rings  

Microsoft Academic Search

We define a weakly finite conductor rings with zero divisors, and examine the transfer of these rings to the trivial ring extensions. These results provide examples of a weakly finite conductor rings that are not finite conductor rings (and so not coherent rings). The last section show that the class of weakly finite conductor rings and the class of 2-coherent

Najib Mahdou

2004-01-01

171

75 FR 55947 - Coordinated Communications  

Federal Register 2010, 2011, 2012, 2013

...109 [Notice 2010-17] Coordinated Communications AGENCY: Federal Election Commission...regulations regarding coordinated communications. The Commission is issuing these...other issues involving the coordinated communications rules. DATES: These rules are...

2010-09-15

172

Template-assisted assembly: scanning tunneling microscopy study of solvent-dependent adlattices of alkyl-derivatized tetrathiafulvalene.  

PubMed

The self-assembly of an adsorbate as a function of the strength of solvent-substrate adsorption is an important yet relatively unexplored subject. In this study, how the strength of solvent-substrate adsorption and solvent-solvent attraction affects the assembly of tetrakis(octadecylthio)tetrathiafulvalene (1) is scrutinized by scanning tunneling microscopy (STM). For solvents with strong intermolecular interactions and adsorption onto graphite, such as long n-alkanes (C(n)H(2n+2), n ? 13), STM reveals that the solvent molecules form lamellae which become a template to direct the assembly of 1 into one-dimensional arrays. The lengths of one of the unit cell vectors for the assemblies are increased and well correlated with the solvent sizes. In situ STM monitoring of 1 introduced onto graphite with preadsorbed n-tetradecane adlattices shows that the developed assemblies of 1 have striped features aligned parallel to the underlying template. In contrast, for solvents with weak adsorption, such as short n-alkanes (C(n)H(2n+2), n ? 12), toluene, and 1,2,4-trichlorobenzene, the adlattice structures of 1 are solvent-independent. PMID:22077481

Lee, Shern-Long; Chu, Yi-Chen; Wu, Hung-Jen; Chen, Chun-Hsien

2012-01-10

173

Effect of solvents on obligately anaerobic bacteria.  

PubMed

Growth of Acetobacterium woodii and Clostridium sporogenes was studied in the presence of water-immiscible solvents. Nitrogen purging, vacuum distillation or distillation under nitrogen were all suitable as methods to remove oxygen from the solvents, since growth rates and yields of A. woodii were unaffected in the presence of tetradecane which had been degassed by these methods. Varying the solvent volume from 20% to 80% of the culture volume had little effect on growth rate of A. woodii. A.woodii was relatively sensitive to organic solvents since growth was inhibited by alkanes with logP(octanol/water) values below 7.1. C. sporogenes was less solvent sensitive, since it grew without inhibition when the logP of the solvent was > or = 6.6. Nevertheless, both A. woodii and C. sporogenes were more sensitive to solvent polarity than aerobic bacteria. PMID:18083050

Rodriguez Martinez, Maria Fernanda; Kelessidou, Niki; Law, Zoe; Gardiner, John; Stephens, Gill

2008-02-01

174

Variation and decomposition of the partial molar volume of small gas molecules in different organic solvents derived from molecular dynamics simulations  

NASA Astrophysics Data System (ADS)

The partial molar volumes, bar V_i, of the gas solutes H2, CO, and CO2, solvated in acetone, methanol, heptane, and diethylether are determined computationally in the limit of infinite dilution and standard conditions. Solutions are described with molecular dynamics simulations in combination with the OPLS-aa force field for solvents and customized force field for solutes. bar V_i is determined with the direct method, while the composition of bar V_i is studied with Kirkwood-Buff integrals (KBIs). Subsequently, the amount of unoccupied space and size of pre-formed cavities in pure solvents is determined. Additionally, the shape of individual solvent cages is analyzed. Calculated bar V_i deviate only 3.4 cm3 mol-1 (7.1%) from experimental literature values. Experimental bar V_i variations across solutions are reproduced qualitatively and also quantitatively in most cases. The KBI analysis identifies differences in solute induced solvent reorganization in the immediate vicinity of H2 (<0.7 nm) and solvent reorganization up to the third solvation shell of CO and CO2 (<1.6 nm) as the origin of bar V_i variations. In all solutions, larger bar V_i are found in solvents that exhibit weak internal interactions, low cohesive energy density and large compressibility. Weak internal interactions facilitate solvent displacement by thermal solute movement, which enhances the size of solvent cages and thus bar V_i. Additionally, attractive electrostatic interactions of CO2 and the solvents, which do not depend on internal solvent interactions only, partially reversed the bar V_i trends observed in H2 and CO solutions where electrostatic interactions with the solvents are absent. More empty space and larger pre-formed cavities are found in solvents with weak internal interactions, however, no evidence is found that solutes in any considered solvent are accommodated in pre-formed cavities. Individual solvent cages are found to be elongated in the negative direction of solute movement. This wake behind the moving solute is more pronounced in case of mobile H2 and in solvents with weaker internal interactions. However, deviations from a spherical solvent cage shape do not influence solute-solvent radial distribution functions after averaging over all solvent cage orientations and hence do not change bar V_i. Overall, the applied methodology reproduces bar V_i and its variations reliably and the used bar V_i decompositions identify the underlying reasons behind observed bar V_i variations.

Klähn, Marco; Martin, Alistair; Cheong, Daniel W.; Garland, Marc V.

2013-12-01

175

Atomistic simulation based prediction of the solvent effect on the molecular mobility and glass transition of poly (methyl methacrylate)  

NASA Astrophysics Data System (ADS)

We present an investigation of the retained solvent effect on the glass transition temperature (Tg) of poly(methyl methacrylate) (PMMA) through all-atom molecular dynamics simulations. Addition of a weakly interactive solvent, tetrahydrofuran (THF), causes a depression of the PMMA Tg that can be identified through an analysis of the mean squared displacement of the polymer chains from atomistic trajectories. Our results are in very good agreement with an atomistically informed theoretical model based on free volume theory and demonstrate the applicability of molecular simulation to discern solvent effects on polymer thermomechanical behavior in silico.

Mishra, Shawn; Keten, Sinan

2013-01-01

176

Coordination polymer gels with important environmental and biological applications.  

PubMed

Coordination Polymer Gels (CPGs) constitute a subset of solid-like metal ion and bridging organic ligand structures (similar to metal-organic frameworks) that form multi-dimensional networks through a trapped solvent as a result of non-covalent interactions. While physical properties of these gels are similar to conventional high molecular weight organic polymer gels, coordination polymer gel systems are often fully reversible and can be assembled and disassembled in the presence of additional energy (heat, sonication, shaking) to give a solution of solvated gelators. Compared to gels resulting from purely organic self-assembled low molecular weight gelators, metal ions incorporated into the fibrilar networks spanning the bulk solvent can impart CPGs with added functionalities. The solid/liquid nature of the gels allows for species to migrate through the gel system and interact with metals, ligands, and the solvent. Chemosensing, catalysis, fluorescence, and drug-delivery applications are some of the many potential uses for these dynamic systems, taking advantage of the metal ion's coordination, the organic polydentate ligand's orientation and functionality, or a combination of these properties. By fine tuning these systems through metal ion and ligand selection and by directing self-assembly with external stimuli the rational synthesis of practical systems can be envisaged. PMID:23192282

Jung, Jong Hwa; Lee, Ji Ha; Silverman, Julian R; John, George

2013-02-01

177

The transformation from Eulerian to Lagrangian coordinates for solutions with discontinuities  

Microsoft Academic Search

We demonstrate the equivalence of Eulerian and Lagrangian coordinates for weak, discontinuous solutions in one space dimension.\\u000a This transformation also induces a one to one correspondence between the convex extensions, or \\

David H. Wagner

178

IR linear dichroic study of high-symmetry molecules dissolved in a liquid crystal solvent. II. Metal hexacarbonyl complexes M(CO) 6 (M = Mo, Cr)  

NASA Astrophysics Data System (ADS)

The presence of weak specific solvent—solute interactions is proved by studying the splitting of the ? 3(F 1u) band of M(CO) 6 (M = Mo, Cr) in some isotropic electron donor solvents. A similar spectral effect is observed in the smectic, nematic and isotropic phases of the liquid crystal ZLI 1167 (Merck) and is explained by similar interactions. The complex (bisignate) shape of the IR-LD spectra of M(CO) 6 in the anisotropic solvent is considered to be a manifestation of the same solvent effect.

Rogojerov, Marin I.; Arnaudov, Michail G.

1994-05-01

179

Weak Acid Equilibrium  

NSDL National Science Digital Library

Students are asked to calculate the pH of a weak acid aqueous solution. The problems involve a series of generic acids with assigned equilibrium constants (Ka) and total concentrations (Ct). Initially, students are required to hand calculate all problems by algebraic manipulation of the mathematical relationships of the system. The solution is a cubic equation. Through a series of assumptions, the solution is simplified. The assumptions are based on the chemistry of the system given the Ka and Ct for the problem. The problems are then graphically solved. Ultimately, the students develop an Excel worksheet to solve the problems and a Bjerrum plot to display the speciation as a function of pH.

Stapleton, Michael

180

Versatile structure-directing roles of deep-eutectic solvents and their implication in the generation of porosity and open metal sites for gas storage.  

PubMed

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

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

2009-01-01

181

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

PubMed Central

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

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

2009-01-01

182

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

SciTech Connect

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.

Ayhan, Ozan [RWTH Aachen University; Malaestean, Iurie L. [RWTH Aachen University; Ellern, Arkady [Ames Laboratory; van Leusen, Jan [RWTH Aachen University; Baca, Svetlana G. [RWTH Aachen University; Kögerler, Paul [RWTH Aachen University

2014-07-02

183

One-nucleon-induced nonmesonic hypernuclear decay in laboratory coordinates  

SciTech Connect

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.

Galeao, A. P. [Instituto de Fisica Teorica, UNESP, 01140-070 Sao Paulo, SP (Brazil); Barbero, C. [Facultad de Ciencias Exactas, UNLP, 1900 La Plata (Argentina) and Instituto de Fisica La Plata, CONICET, 1900 La Plata (Argentina); De Conti, C. [Campus Experimental de Itapeva, UNESP, 18409-010 Itapeva, SP (Brazil); Krmpotic, F. [Facultad de Ciencias Astronomicas y Geofisicas, UNLP, 1900 La Plata (Argentina) and Instituto de Fisica La Plata, CONICET, 1900 La Plata (Argentina)

2013-05-06

184

Solvent refined coal (SRC) process  

SciTech Connect

This report summarizes the progress of the Solvent Refined Coal (SRC) project by The Pittsburg and Midway Coal Mining Co. at the SRC Pilot Plant in Fort Lewis, Washington and the Gulf Science and Technology Company Process Development Unit (P-99) in Harmarville, Pennsylvania, for the Department of Energy during the month of October, 1980. The Fort Lewis Pilot Plant was shut down the entire month of October, 1980 for inspection and maintenance. PDU P-99 completed two runs during October investigating potential start-up modes for the Demonstration Plant.

Not Available

1980-12-01

185

Electrostatic interactions in critical solvents  

E-print Network

The subtle interplay between critical phenomena and electrostatics is investigated by considering the effective force acting on two parallel walls confining a near-critical binary liquid mixture with added salt. The ion-solvent coupling can turn a non-critical repulsive electrostatic force into an attractive one upon approaching the critical point. However, the effective force is eventually dominated by the critical Casimir effect, the universal properties of which are not altered by the presence of salt. This observation allows a consistent interpretation of recent experimental data.

Markus Bier; Andrea Gambassi; Martin Oettel; S. Dietrich

2011-04-29

186

Generator Coordinate Truncations  

E-print Network

We investigate the accuracy of several schemes to calculate ground-state correlation energies using the generator coordinate technique. Our test-bed for the study is the $sd$ interacting boson model, equivalent to a 6-level Lipkin-type model. We find that the simplified projection of a triaxial generator coordinate state using the $S_3$ subgroup of the rotation group is not very accurate in the parameter space of the Hamiltonian of interest. On the other hand, a full rotational projection of an axial generator coordinate state gives remarkable accuracy. We also discuss the validity of the simplified treatment using the extended Gaussian overlap approximation (top-GOA), and show that it works reasonably well when the number of boson is four or larger.

K. Hagino; G. F. Bertsch; P. -G. Reinhard

2003-04-17

187

Aromatic as well as aliphatic hydrocarbon solvent axonopathy.  

PubMed

Superfund sites that contain mixtures of aromatic and aliphatic solvents represent an undefined health hazard. After prolonged exposure to relatively high levels of certain aliphatic solvents (e.g. n-hexane, 2-hexanone), humans and animals develop a dose-dependent neurodegeneration that occurs clinically as a symmetrical peripheral neuropathy. This is triggered by the action of 2,5-hexanedione (1,2-diacetylethane), a 1,4-diketone (gamma-diketone) metabolite that targets proteins required for the maintenance of neuronal (and testicular Sertoli cell) integrity. Certain aromatic solvents (1,2-diethylbenzene, 1,2,4-triethylbenzene) cause electrophysiological changes consistent with sensorimotor neuropathy in rodents, but the underlying mechanisms and pathogenesis are unclear. Our recent studies show that the o-diacetyl derivative and likely metabolite of 1,2-diethylbenzene, 1,2-diacetylbenzene, behaves as a neurotoxic (aromatic) gamma-diketone of high neurotoxic potency. Rats treated with 1,2-diacetylbenzene develop limb weakness associated with proximal, neurofilament-filled giant axonal swellings comparable to those seen in animals treated with the potent 3,4-dimethyl derivative of 2,5-hexanedione. The blue chromogen induced by treatment with 1,2-diacetylbenzene is under study as a possible urinary biomarker of exposure to aromatic solvents (e.g. 1,2-diethylbenzene, tetralin) with neurotoxic potential. Development and validation of sensitive new biomarkers, especially for non-cancer endpoints, will aid in assessing the health risk associated with exposure to hazardous substances at Superfund sites. PMID:12018006

Spencer, Peter S; Kim, Min Sun; Sabri, Mohammad I

2002-03-01

188

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

NASA Astrophysics Data System (ADS)

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.

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

2011-03-01

189

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

SciTech Connect

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.

Tang Qun [Key Laboratory of Polyoxometalate Science of Ministry of Education, College of Chemistry, Northeast Normal University, Changchun, Jilin 130024 (China); Liu Shuxia, E-mail: liusx@nenu.edu.cn [Key Laboratory of Polyoxometalate Science of Ministry of Education, College of Chemistry, Northeast Normal University, Changchun, Jilin 130024 (China); Liang Dadong; Ma Fengji; Ren Guojian; Wei Feng; Yang Yuan; Li Congcong [Key Laboratory of Polyoxometalate Science of Ministry of Education, College of Chemistry, Northeast Normal University, Changchun, Jilin 130024 (China)

2012-06-15

190

Harmonic coordinates on fractals with finitely ramified cell structure  

E-print Network

We define sets with finitely ramified cell structure, which are generalizations of p.c.f. self-similar sets introduced by Kigami and of fractafolds introduced by Strichartz. In general, we do not assume even local self-similarity, and allow countably many cells connected at each junction point. We prove that if Kigami's resistance form satisfies certain assumptions, then there exists a weak Riemannian metric such that the energy can be expressed as the integral of the norm squared of a weak gradient with respect to an energy measure. Furthermore, we prove that if such a set can be homeomorphically represented in harmonic coordinates, then for smooth functions the weak gradient can be replaced by the usual gradient. We also prove a simple formula for the energy measure Laplacian in harmonic coordinates.

Alexander Teplyaev

2006-06-26

191

Solvent Extraction External Radiation Stability Testing  

SciTech Connect

Personnel irradiated a number of samples of calixarene-based solvent. Analysis of these samples indicated that measurable loss of the calixarene occurred at very high doses (-16 Mrad). No measurable loss of the Cs-7SB modifier occurred at equivalent doses. The primary degradation product, 4-sec-butylphenol, observed during analysis of the samples came from degradation of the modifier. Also, TOA proved more susceptible to damage than the other components of the solvent. The total degradation of the solvent proved relatively minor. The consistent solvent performance, as indicated by the measured D Cs values, after exposure at high total doses serves as evidence of the relatively low degree of degradation of the solvent components. Additional tests employing internal irradiation of solvents with both simulants and SRS tank waste will be completed by the end of March 2001 to provide confirmation of the results presented herein.

Peterson, R.A.

2001-01-05

192

Solvent dependent photophysical properties of dimethoxy curcumin  

NASA Astrophysics Data System (ADS)

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 (?f), 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 (?f) and fluorescence lifetime (?f) of DMC were also measured in different solvents at room temperature. The results indicated that with increasing solvent polarity, ?f increased linearly, which has been accounted for the decrease in non-radiative rate by intersystem crossing (ISC) processes.

Barik, Atanu; Indira Priyadarsini, K.

2013-03-01

193

Block coordination copolymers  

DOEpatents

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.

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

2012-12-04

194

Block coordination copolymers  

DOEpatents

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.

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

2012-11-13

195

Coordinating Texas Water Research  

E-print Network

centers. #12;"Texas Panel on Water" Potential Activities 1. Regularly convene a panel of experts 2. ReviewCoordinating Texas Water Research Jay Banner and Eric Hersh Environmental Science Institute and Jackson School of Geosciences, The University of Texas at Austin CIESS Water Forum III October 14, 2013

Yang, Zong-Liang

196

Block coordination copolymers  

DOEpatents

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.

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

2014-11-11

197

Sex Equity Coordinator's Handbook.  

ERIC Educational Resources Information Center

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…

Rubenstein, Dorothy; Sillman, Donna

198

Biochemistry 448 Course Coordinator  

E-print Network

Biochemistry 448 Course Coordinator Dr Scott Covey scott.covey@ubc.ca 604-822-1949 Course Description This is an independent biochemistry driven research project performed under the supervision independent research and lab work. Although biochemistry honours students have priority majors student can

Strynadka, Natalie

199

Palantír: Coordinating Distributed Workspaces  

Microsoft Academic Search

Distributed software development suffers from limited collaboration capabilities, as developers are unable to easily coordinate their efforts across physical boundaries. Different fields, such as CSCW and groupware, have at- tempted to bridge this gap, but few of the approaches developed so far have been incorporated in current soft- ware development environments. Configuration Manage- ment (CM) systems are vital to any

Anita Sarma; André Van Der Hoek

2002-01-01

200

Coordinating author Maurizio Cocchi  

E-print Network

1 #12;2 Coordinating author Maurizio Cocchi Etaflorence Renewable Energies www.etaflorence.it Contributing authors Lars Nikolaisen Danish Technological Institute www.dti.dk Martin Junginger, Chun been taken when compiling the report, the authors disclaim any legal liability or responsibility

201

Coordinating chiral ionic liquids.  

PubMed

A practical synthesis of novel coordinating chiral ionic liquids with an amino alcohol structural motif was developed starting from commercially available amino alcohols. These basic chiral ionic liquids could be successfully applied as catalysts in the asymmetric alkylation of aldehydes and gave high enantioselectivities of up to 91% ee. PMID:24163003

Vasiloiu, Maria; Leder, Sonja; Gaertner, Peter; Mereiter, Kurt; Bica, Katharina

2013-12-14

202

Weak measurements in quantum mechanics  

E-print Network

The article recapitulates the concept of weak measurement in its broader sense encapsulating the trade between asymptotically weak measurement precision and asymptotically large measurement statistics. Essential applications in time-continuous measurement and in postselected measurement are presented both in classical and in quantum contexts. We discuss the anomalous quantum weak value in postselected measurement. We concentrate on the general mathematical and physical aspects of weak measurements and we do not expand on their interpretation. Particular applications, even most familiar ones, are not subject of the article which was written for Elsevier's Encyclopedia of Mathematical Physics.

Lajos Diosi

2005-05-10

203

Fluorous solvent for cell culture  

Microsoft Academic Search

Incubation of mouse melanoma B16 cells in fluorous solvents with low boiling point such as perfluoromethylcyclohexane, 1,1,1,3,3,3-hexafluoro-2-propanol, ethylpentafluoropropionate resulted in cell death. However, cells lived up to 2 days in fluorous alcohols such as 2,2,3,3,4,4,5,5-octafluoro-1-pentanol and 3,3,4,4,5,5,6,6,6-nonafluoro-1-hexanol with relatively higher fluorine content. Remarkably, cells survived deprived of nutrition up to 4 days when incubated in 2,2,3,3,4,4,5,5,6,6,6-undecafluoro-1-hexanol or in 2,2,3,3,4,4,5,5,6,6,7,7-dodecafluoroheptanol that

Maria Carmelita Z. Kasuya; Xiaonan Wen; Kenichi Hatanaka; Kageyasu Akashi

2011-01-01

204

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

PubMed

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(?) and C(?) 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. PMID:25544680

Topham, Christopher M; Smith, Jeremy C

2015-02-01

205

Prussian blue nanospheres synthesized in deep eutectic solvents  

NASA Astrophysics Data System (ADS)

A novel route for controlled synthesis of Prussian blue nanospheres (PB NSs) with different sizes by using deep eutectic solvents (DES) as both solvent and template provider was demonstrated. The size-controlled PB NSs were obtained directly by the coordination of Fe(CN)64- ion with Fe3+ ion in the DES. The probable mechanism of formation of PB NSs was discussed based on the characterization results of UV-visible, X-ray diffraction, X-ray photoelectronic spectrum and transfer electron microscopy. Furthermore, the electrochemical and electrocatalytic properties of the synthesized PB NSs were investigated, and it has demonstrated that the PB NSs exhibited excellent catalytic activity for H2O2 reduction, and then extended this strategy to glucose sensing, by detecting H2O2 formed from the enzymatic reaction of glucose oxidase with its substrate glucose. The linear calibration range for glucose was from 0.9 ?M to 0.12 mM, with a correlation coefficient of 0.998. The limit of detection was 0.3 ?M and the sensitivity was 61.7 A cm-2 M-1. The present study provides a general platform for the controlled synthesis of novel nanomaterials in DES and can be extended to other optical, electronic and magnetic nanocompounds.A novel route for controlled synthesis of Prussian blue nanospheres (PB NSs) with different sizes by using deep eutectic solvents (DES) as both solvent and template provider was demonstrated. The size-controlled PB NSs were obtained directly by the coordination of Fe(CN)64- ion with Fe3+ ion in the DES. The probable mechanism of formation of PB NSs was discussed based on the characterization results of UV-visible, X-ray diffraction, X-ray photoelectronic spectrum and transfer electron microscopy. Furthermore, the electrochemical and electrocatalytic properties of the synthesized PB NSs were investigated, and it has demonstrated that the PB NSs exhibited excellent catalytic activity for H2O2 reduction, and then extended this strategy to glucose sensing, by detecting H2O2 formed from the enzymatic reaction of glucose oxidase with its substrate glucose. The linear calibration range for glucose was from 0.9 ?M to 0.12 mM, with a correlation coefficient of 0.998. The limit of detection was 0.3 ?M and the sensitivity was 61.7 A cm-2 M-1. The present study provides a general platform for the controlled synthesis of novel nanomaterials in DES and can be extended to other optical, electronic and magnetic nanocompounds. Electronic supplementary information (ESI) available. See DOI: 10.1039/c2nr31830j

Sheng, Qinglin; Liu, Ruixiao; Zheng, Jianbin

2012-10-01

206

Solvent effects on ground and excited electronic state structures of p-nitroaniline  

NASA Astrophysics Data System (ADS)

Resonance Raman intensities of p-nitroaniline, a prototypical "push-pull" chromophore with a large first hyperpolarizability (?), have been measured in dilute solution in five solvents having a wide range of polarities (cyclohexane, 1,4-dioxane, dichloromethane, acetonitrile, and methanol) at excitation wavelengths spanning the strong near-ultraviolet charge-transfer absorption band. The absolute Raman excitation profiles and absorption spectra are simulated using time-dependent wave packet propagation techniques to determine the excited-state geometry changes along the five or six principal Raman-active vibrations as well as estimates of the solvent reorganization energies. The total vibrational reorganization energy decreases and the solvent reorganization energy increases with increasing solvent polarity in all solvents except methanol, where specific hydrogen-bonding interactions may be important. The dimensionless normal coordinate geometry changes obtained from the resonance Raman analysis are converted to actual bond length and bond angle changes with the aid of normal mode coefficients from a ground-state density functional theory calculation. The geometry changes upon electronic excitation involve predominantly the Cphenyl-Nnitro, N-O, and phenyl C2-C3 bond lengths, with little involvement of the amino group. Nonresonant Raman spectra in 1,4-dioxane, dichloromethane, ethyl acetate, acetone, acetonitrile, and methanol show only a very small solvent dependence of the vibrational frequencies. This suggests that changing the solvent affects the excited state more than the ground state, calling into question two-state models that treat the ground and charge-transfer excited states as linear combinations of neutral and zwitterionic basis states with solvent dependent coefficients.

Moran, Andrew M.; Kelley, Anne Myers

2001-07-01

207

Green Solvents for Precision Cleaning  

NASA Technical Reports Server (NTRS)

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 moderate processing conditions of 323 K, 13.8 MPa, 30 min and 750 rpm.

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

2013-01-01

208

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

PubMed

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

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

209

Mechanisms of solute rejection in solvent resistant nanofiltration: the effect of solvent on solute rejection.  

PubMed

The separation performance of solvent resistant nanofiltration (SRNF) membranes was studied in a systematic way to elucidate the complex mechanisms involved in rejection of solutes. Rejection of three dyes (Sudan II, Sudan Black, Sudan 408) from common organic solvents (methanol, ethanol, acetone, methyl ethyl ketone, toluene and n-hexane) through a polyimide based SRNF membrane, STARMEM™122, was studied. It was found that the rejection of the STARMEM™122 membrane was lower than that indicated by the manufacturer. The experimental observations for Sudan II were not promising for the rejection study as they were lower than expected. Sudan Black and Sudan 408, which are larger solutes than Sudan II, provided more interesting insights. The effects of the solvent on the membrane and solute were studied separately. A higher permeation rate of ketones and alcohols was observed, while permeabilities of non-polar solvents were low which shows that this membrane shows higher affinity toward semi-polar solvents (alcohols, ketones). The effect of the solvent on the solute's rejection, based on the results for Sudan Black and Sudan 408, was studied for solvents in the same chemical groups, since the membrane showed a similar separation performance for solvents with similar functional groups (e.g. alcohols). The effect of solvent on solute molecular size was investigated by using simulation with Molecular Dynamics. It was shown that the effective size of a molecule is dependent on the solvent due to solvation and hydration of the solute by the solvent. The size of the solute in the solvent belonging to a similar family was studied separately. It was clear that the rejection was influenced by molecular size of the solute in the same group of solvents. A surprising negative rejection of solutes was achieved for n-hexane. Although solutes in n-hexane have higher volume compared to those in other solvents, the affinity between the solute and membrane increases the solute permeation in the presence of n-hexane. The affinity of solvent and solute for the membrane was investigated by means of solubility parameters for solvents within the same chemical family. In two different systems including two different solvents and one solute (Sudan Black and methanol, Sudan Black and ethanol), lower rejection (in this case for Sudan Black and methanol) was achieved when the solutes have higher affinity toward the solvent. Finally, it was found that in a system comprising the solvent, solute and membrane, interactions between solvent and membrane have much more effect on separation than solvent-solute interactions. PMID:20842303

Darvishmanesh, Siavash; Degrève, Jan; Van der Bruggen, Bart

2010-10-28

210

Plant Breeding Coordinating Committee  

NSDL National Science Digital Library

To view additional success stories click on the link in the left menu Please click here to report your plant breeding success stories.  Click on TCAP logo to see the Economic impact of USDA-NIFA small grains CAPsThe Plant Breeding Coordinating Committee (SCC 080) is the USDA-sponsored advisory group of representatives from land grant universities.  The Plant Breeding Coordinating Committee represents national plant breeding with a focus on education in the broader sense, including providing information to the public and administrators, and encouraging the development of formal educational opportunities, continuing education, and lifelong learning. Mission: To provide a forum for leadership on issues and opportunities of strategic importance to national core competency in plant breeding research and education Membership: The PBCC members will consist of the representatives of the SCC-080 committee and others by request. 

211

Conformal Fermi Coordinates  

E-print Network

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 ef...

Dai, Liang; Schmidt, Fabian

2015-01-01

212

Spherical Polar Coordinates  

NSDL National Science Digital Library

This applet displays a point or an volume in three dimensions using spherical coordinates. The user can change the radius and angles and move the point of view. It should be noted that the author uses a different naming convention for the angles than is common for physics in the United States, using θ for the azimuthal angle and φ for the polar angle. This is part of a large collection of physics and math applets by the author.

Reddy, Surendranath

2011-06-17

213

Online Market Coordination  

Microsoft Academic Search

The aim of this paper is to deal with the problem of coordination for online markets where a seller registers to an online\\u000a market to sell an item. The seller and the owner of the market then form an alliance to generate revenue through online sales.\\u000a However, the efficiency and stability of the alliance highly relies on the contract that

Masabumi Furuhata; Dongmo Zhang; Laurent Perrussel

2008-01-01

214

Adiabatic Charge Dynamics in Molecules Dissolved in A Polar Solvent. Application to Charge Migration in DNA  

NASA Astrophysics Data System (ADS)

We develop an adiabatic hopping model for charge migration through molecules dissolved in a polar liquid (water), based on an analytical approach [1]. The charge hopping between donor and acceptor states is due to a rare fluctuation of the solvent polarization forming a deeper well at the target places. The results are applied to the photoexcited hole migration in DNA [2] using the model parameters, obtained from the first principles studies. Theory can explain the length dependence of the transfer rate, becoming distant independent at long distances where correlations in fluctuations are weak, and one sees low absolute value of charge hopping rate, defined entirely by the slow kinetics of the solvent. Strong energy and weak temperature dependence of the transfer rate, observed experimentally can be due to the entropy control of water fluctuations at room temperature. Clarifying experiments are suggested. 1.A. L. Burin, et al, Phys. Rev. Lett. 86, 5616, 2001. 2.F. D. Lewis, et al, Nature 406, 51, 2000

Burin, A. L.; Berlin, Yu. A.; Kurnikov, I.; Ratner, M. A.

2002-03-01

215

Hipparchus' coordinate system  

NASA Astrophysics Data System (ADS)

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.

Duke, Dennis W.

2002-07-01

216

Are deep eutectic solvents benign or toxic?  

Microsoft Academic Search

In continuation of investigation for environmentally benign protocol for new solvents termed deep eutectic solvents (DESs), it is herein reported results concerning the toxicity and cytotoxicity of choline chloride (ChCl) based DESs with four hydrogen bond donors including glycerine, ethylene glycol, triethylene glycol and urea. The toxicity was investigated using two Gram positive bacteria Bacillus subtilis and Staphylococcus aureus, and

M. Hayyan; M. A. Hashim; A. Hayyan; M. A. Al-Saadi; I. M. AlNashef; M. E. S. Mirghani; O. K. Saheed

2013-01-01

217

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, ...

218

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. his technique involves the injection of a solvent mixture (e.g., water plus alcohols) that enhances contaminant solubility, reduces the retardation factor, a...

219

Structure of the polymer-solvent interface  

NASA Technical Reports Server (NTRS)

The first measurements of ellipticities from the liquid-liquid interface between polymer and solvent mixtures near their consolute points are reported. When scaled according to theory the ellipticities of high molecular weight polystyrene + solvent mixtures are consistent with those from simple, low molecular weight mixtures. The universal value of the scaled ellipticity is approximately 20 percent lower than that predicted by present theories.

Miles, Danny G., Jr.; Schmidt, James W.

1990-01-01

220

SAFETY OF ORGANIC SOLVENTS IN WASTE TANKS  

SciTech Connect

This report addresses flash points and flammability limits of flammable gases found in waste tanks, primarily hydrocarbon mixtures derived from waste solvents. The effect of vapor pressure is discussed. Particular attention is given to Purex solvent. The pertinent facts are then applied to the safety of the waste tanks of concern.

Van Tuyl, H. H.

1983-08-01

221

Coal processing: the Exxon donor solvent process  

Microsoft Academic Search

The development of the Exxon coal liquefaction process over 10 years is described. Exxon is using lower temperatures and lower pressures (approximately 100 bar) than were used in the Bergius process. The donor solvent is produced in a separate, fixed bed, catalytic hydrogenation step. Early research was broad in scope including, both hydrogenated and unhydrogenated recycle solvent studies. Alternate solids\\/liquids

L. E. Furlong; E. Effron; L. W. Vernon; E. L. Wilson

1976-01-01

222

Gallium complexes and solvent extraction of gallium  

SciTech Connect

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.

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

1988-05-03

223

Solvent Cluster Size and Colligative Properties  

Microsoft Academic Search

It is proposed that the occurrence of colligative phenomena is a result of structured aggregates of solvent molecules which exist within the liquid medium. In a solution these formations are smaller than in the pure solvent. Using simple kinetic arguments it is shown how this difference in cluster size shifts the equilibria which establish vapour pressure, as well as the

J. G. Watterson

1987-01-01

224

ENHANCED PROCESSING OF GREEN SOLVENTS - PHASE I  

EPA Science Inventory

Solvents are a valuable processing tool in the chemical and related industries. Solvents are used to enhance mass transfer, heat transfer and in most cases are a processing aid and eventually are not used in the final product but to enhance the fabrication of the final pr...

225

Improved Supercritical-Solvent Extraction of Coal  

NASA Technical Reports Server (NTRS)

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.

Compton, L.

1982-01-01

226

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...

227

Weak amenability and 2-weak amenability of Beurling algebras  

NASA Astrophysics Data System (ADS)

Let be a Beurling algebra on a locally compact abelian group G. We look for general conditions on the weight which allows the vanishing of continuous derivations of . This leads us to introducing vector-valued Beurling algebras and considering the translation of operators on them. This is then used to connect the augmentation ideal to the behavior of the derivation space. We apply these results to give examples of various classes of Beurling algebras which are weakly amenable, 2-weakly amenable or fail to be even 2-weakly amenable.

Samei, Ebrahim

2008-10-01

228

Organic solvent regeneration of granular activated carbon  

NASA Astrophysics Data System (ADS)

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.

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

1982-09-01

229

Catalyst- and solvent-dependent stereodivergence in the intramolecular Et(2)Zn/Pd(0) -promoted carbonyl propargylation: mechanistic implications.  

PubMed

Carbonyl-tethered propargylic benzoates undergo intramolecular carbonylpropargylation upon treatment with Et2 Zn in the presence of a catalytic amount of Pd(0) with the formation of 2-alkynylcyclopentanol products. A ligand/solvent effect on the cis/trans selectivity (referring to the relative positions of alkynyl and OH groups) of ring-closure has been found. In a non-coordinating solvent (benzene), increasing the electron-donating ability of the phosphine ligand (while decreasing its dissociation ability) leads to an increased tendency towards the trans product. On the other hand, the combination of a coordinating solvent (THF) and PPh3 , an easily dissociated phosphine, results in the exclusive formation of cis products. Experimental and computational results are compatible with a divergent behavior of an allenylethylpalladium intermediate that partitions between competitive carbonyl-addition and transmetalation pathways, each leading to a different diastereoisomer. These results also suggest that the dissociating ability of the phosphine regulates that behavior. PMID:23963967

Arrate, Mónica; Durana, Aritz; Lorenzo, Paula; de Lera, Ángel R; Álvarez, Rosana; Aurrecoechea, José M

2013-10-01

230

Organic solvent vapor effects on phase transition of ? and ? tegafur upon grinding with solvent additives.  

PubMed

Solvent effects on ? tegafur (5-fluoro-1-(tetrahydro-2-furyl)uracil) phase transition to ? tegafur during grinding with solvent additive, as well as phase transition in samples exposed to 95% relative solvent vapor pressure has been studied in this research. Samples containing 0.5% and 0.1% of ? tegafur in ? and ? tegafur mixture, as well as samples of pure ? tegafur were ground with different solvent additives, and conversion degrees depending on the solvent were determined using PXRD method. Samples with ? and ? tegafur weight fraction of 1:1 were exposed to 95% relative solvent vapor pressure, and phase transition rates were determined. Solubility of ? tegafur, solvent sorption and desorption behavior on ? and ? tegafur have been examined. It was found that the conversion degree of ? tegafur to ? tegafur mainly depends on solubility of ? tegafur in the relevant solvent, and the conversion degree to ? tegafur is higher in such solvents, where solubility of ? tegafur is higher. The samples ground in a ball mill with solvent additive had a trend of phase transition dynamics from ? tegafur to ? tegafur similar to the samples exposed to 95% relative solvent vapor pressure. PMID:23318369

Bobrovs, Raitis; Save?jeva, Olga; Kapace, Agnese; Plauka, Zane; Acti?š, Andris

2013-02-25

231

40 CFR Table 5 to Subpart Vvvv of... - Default Organic HAP Contents of Solvents and Solvent Blends  

Code of Federal Regulations, 2010 CFR

...2010-07-01 2010-07-01 true Default Organic HAP Contents of Solvents and Solvent Blends...to Subpart VVVV of Part 63—Default Organic HAP Contents of Solvents and Solvent Blends...63.5758(a)(6), when detailed organic HAP content data for solvent blends...

2010-07-01

232

Solvent effects and vibrational dependence in electrochromic spectra of carotenoids  

NASA Astrophysics Data System (ADS)

Electrochromic (Stark effect) spectra of three carotenoids, ?-carotene, lutein and violaxanthin, were obtained in glassy matrices at low temperature. When analyzed in the framework of the theory of electrochromism they were found to contain a remarkable contribution from the second derivative of the absorption spectrum, equivalent to a substantial change in dipole moment (3-5 D) on electronic excitation, in addition to the usual polarizability term. These dipole moments only weakly depend on solvent polarity; this puts in doubt the induced dipole model. In the case of violaxanthin, a variability of the electro-optical parameters along the electrochromic spectrum was found, which is related to the type of vibration involved in the electronic transition. An analogous effect was also noted for tetradecaheptaene chromophore in amphotericin B. These observations strongly indicate an essential role of vibronic coupling in determining the electro-optical parameters of carotenoids.

Krawczyk, StanisAw; Daniluk, Andrzej

1995-04-01

233

Weak-shock reflection factors  

SciTech Connect

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.

Reichenbach, H. [Ernst Mach Inst., Freiburg (Germany); Kuhl, A.L. [Lawrence Livermore National Lab., El Segundo, CA (United States)

1993-09-07

234

Geometry of Weak Stability Boundaries  

E-print Network

The notion of a weak stability boundary has been successfully used to design low energy trajectories from the Earth to the Moon. The structure of this boundary has been investigated in a number of studies, where partial results have been obtained. We propose a generalization of the weak stability boundary. We prove analytically that, in the context of the planar circular restricted three-body problem, under certain conditions on the mass ratio of the primaries and on the energy, the weak stability boundary about the heavier primary coincides with a branch of the global stable manifold of the Lyapunov orbit about one of the Lagrange points.

Edward Belbruno; Marian Gidea; Francesco Topputo

2012-04-06

235

Self-esterification of fulvic acid model compounds in methanolic solvents as observed by electrospray ionization mass spectrometry.  

PubMed

The self-esterification of two fulvic acid model compounds in methanolic solvents was studied by electrospray ionization mass spectrometry (ESI-MS). The strongly acidic tetrahydrofurantetracarboxylic acid rapidly self-esterified to form mono- and dimethyl esters when stored in methanol, even at reduced temperatures. The weakly acidic analogue, cyclopentanetetracarboxylic acid, reacted minimally under the same conditions. The use of 50:50 methanol/water as a solvent reduced self-esterification of the strong acid. However, the presence of water promoted the formation of multiply charged ions in the ESI mass spectra. The use of water and 50:50 acetonitrile/water as solvents eliminated self-esterification but the mass spectra still contained multiply charged ions. This study implies that the use of methanolic solvents with humic substances may compromise analytical data through the formation of methyl esters. PMID:11921263

McIntyre, Cameron; McRae, Christopher; Jardine, Daniel; Batts, Barry D

2002-01-01

236

Student Leadership Program Coordinator Application  

E-print Network

Student Leadership Program Coordinator Application Summer 2012 ­ Spring 2013 Please direct all (Preferable Start Date 7/1) ____ Leadership Events and Training Program Coordinator (Preferable Start Date 7 leadership skills do you hope to strengthen from a Student Leadership Program Coordinator position? 2

Sheridan, Jennifer

237

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...

238

27 CFR 21.125 - Rubber hydrocarbon solvent.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Rubber hydrocarbon solvent. 21.125...Specifications for Denaturants § 21.125 Rubber hydrocarbon solvent. (a) Rubber hydrocarbon solvent is a petroleum derivative. (b) Distillation...

2010-04-01

239

Prussian blue nanospheres synthesized in deep eutectic solvents.  

PubMed

A novel route for controlled synthesis of Prussian blue nanospheres (PB NSs) with different sizes by using deep eutectic solvents (DES) as both solvent and template provider was demonstrated. The size-controlled PB NSs were obtained directly by the coordination of Fe(CN)(6)(4-) ion with Fe(3+) ion in the DES. The probable mechanism of formation of PB NSs was discussed based on the characterization results of UV-visible, X-ray diffraction, X-ray photoelectronic spectrum and transfer electron microscopy. Furthermore, the electrochemical and electrocatalytic properties of the synthesized PB NSs were investigated, and it has demonstrated that the PB NSs exhibited excellent catalytic activity for H(2)O(2) reduction, and then extended this strategy to glucose sensing, by detecting H(2)O(2) formed from the enzymatic reaction of glucose oxidase with its substrate glucose. The linear calibration range for glucose was from 0.9 ?M to 0.12 mM, with a correlation coefficient of 0.998. The limit of detection was 0.3 ?M and the sensitivity was 61.7 A cm(-2) M(-1). The present study provides a general platform for the controlled synthesis of novel nanomaterials in DES and can be extended to other optical, electronic and magnetic nanocompounds. PMID:23034657

Sheng, Qinglin; Liu, Ruixiao; Zheng, Jianbin

2012-11-01

240

Identification and Characterization of Solvent Filled Channels in Human Ferrochelatase†¥  

PubMed Central

Ferrochelatase catalyzes the formation of protoheme from two potentially cytotoxic products, iron and protoporphyrin IX. While much is known from structural and kinetic studies on human ferrochelatase of the dynamic nature of the enzyme during catalysis and the binding of protoporphyrin IX and heme, little is known about how metal is delivered to the active site and how chelation occurs. Analysis of all ferrochelatase structures available to date reveals the existence of several solvent filled channels which originate at the protein surface and continue to the active site. These channels have been proposed to provide a route for substrate entry, water entry and proton exit during the catalytic cycle. In order to begin to understand the functions of these channels, a number of variants which line these solvent filled channels were investigated in vitro and in vivo. Data presented herein support the role of one of these channels, which originates at the surface residue H240, in iron delivery to the active site. Structural studies of the arginyl variant of the conserved residue F337, which resides at the back of the active site pocket, suggest that it not only regulates the opening and closing of active site channels, but also plays a role in regulating the enzyme mechanism. These data provide insight into the movement of substrate and water into and out of the active site and how this movement is coordinated with the reaction mechanism. PMID:22712763

Medlock, Amy E.; Najahi-Missaoui, Wided; Ross, Teresa A.; Dailey, Tamara A.; Burch, Joseph; O’Brien, Jessica R.; Lanzilotta, William N.; Dailey, Harry A.

2012-01-01

241

Solvent exposure in construction and maintenance painting.  

PubMed

Exposure to solvents in interior house painting was determined by industrial hygiene surveys and questionnaires on work history. Painting work was observed in 92 work situations at 18 sites, mainly during maintenance work. The effects of the size of the work area, the volume of air, the type of paint, the amount used, the method of application, and the use of ventilation on the solvent concentrations were also studied. In small, poorly ventilated rooms the concentration of solvent naphtha averaged 275 ppm when alkyd paints were used. Wall and ceiling painting with alkyd paints yielded an average solvent naphtha concentration of 210 ppm, and window and door painting 80 ppm. The presence of a strong draft reduced the solvent concentrations by two-thirds. The painters' average lifetime dose of solvent naphtha was 12.2 kg, the average annual dose 0.54 kg. These levels decreased over the study period. The mean 8-h concentration of solvent naphtha in the breathing zone averaged 40 ppm over the painters' total worklife. PMID:6494847

Riala, R; Kalliokoski, P; Pyy, L; Wickström, G

1984-08-01

242

Organic Solvent Tolerant Lipases and Applications  

PubMed Central

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

Kanwar, Shamsher S.

2014-01-01

243

Auditory dysfunction associated with solvent exposure  

PubMed Central

Background A number of studies have demonstrated that solvents may induce auditory dysfunction. However, there is still little knowledge regarding the main signs and symptoms of solvent-induced hearing loss (SIHL). The aim of this research was to investigate the association between solvent exposure and adverse effects on peripheral and central auditory functioning with a comprehensive audiological test battery. Methods Seventy-two solvent-exposed workers and 72 non-exposed workers were selected to participate in the study. The test battery comprised pure-tone audiometry (PTA), transient evoked otoacoustic emissions (TEOAE), Random Gap Detection (RGD) and Hearing-in-Noise test (HINT). Results Solvent-exposed subjects presented with poorer mean test results than non-exposed subjects. A bivariate and multivariate linear regression model analysis was performed. One model for each auditory outcome (PTA, TEOAE, RGD and HINT) was independently constructed. For all of the models solvent exposure was significantly associated with the auditory outcome. Age also appeared significantly associated with some auditory outcomes. Conclusions This study provides further evidence of the possible adverse effect of solvents on the peripheral and central auditory functioning. A discussion of these effects and the utility of selected hearing tests to assess SIHL is addressed. PMID:23324255

2013-01-01

244

Environmental Impacts on Nuclear Reprocessing Solvents  

NASA Astrophysics Data System (ADS)

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 (?13C) 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.

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

2009-12-01

245

Ten years of probabilistic estimates of biocrystal solvent content: new insights via nonparametric kernel density estimate.  

PubMed

The probabilistic estimate of the solvent content (Matthews probability) was first introduced in 2003. Given that the Matthews probability is based on prior information, revisiting the empirical foundation of this widely used solvent-content estimate is appropriate. The parameter set for the original Matthews probability distribution function employed in MATTPROB has been updated after ten years of rapid PDB growth. A new nonparametric kernel density estimator has been implemented to calculate the Matthews probabilities directly from empirical solvent-content data, thus avoiding the need to revise the multiple parameters of the original binned empirical fit function. The influence and dependency of other possible parameters determining the solvent content of protein crystals have been examined. Detailed analysis showed that resolution is the primary and dominating model parameter correlated with solvent content. Modifications of protein specific density for low molecular weight have no practical effect, and there is no correlation with oligomerization state. A weak, and in practice irrelevant, dependency on symmetry and molecular weight is present, but cannot be satisfactorily explained by simple linear or categorical models. The Bayesian argument that the observed resolution represents only a lower limit for the true diffraction potential of the crystal is maintained. The new kernel density estimator is implemented as the primary option in the MATTPROB web application at http://www.ruppweb.org/mattprob/. PMID:24914969

Weichenberger, Christian X; Rupp, Bernhard

2014-06-01

246

Interfacial tension of evaporating emulsion droplets containing amphiphilic block copolymers: effects of solvent and polymer composition.  

PubMed

Evaporating droplets of volatile organic solvent containing amphiphilic block copolymers may undergo hydrodynamic instabilities that lead to dispersal of copolymer micelles into the surrounding aqueous phase. As for related phenomena in reactive polymer blends and oil/water/surfactant systems, this process has been ascribed to a nearly vanishing or transiently negative interfacial tension between the water and solvent phases induced by adsorption of copolymer to the interface. In this report, we investigate the influence of the choice of organic solvent and polymer composition for a series of polystyrene-b-poly(ethylene oxide) (PS-PEO) diblock copolymers, by in situ micropipette tensiometry on evaporating emulsion drops. These measurements suggest that the sensitivity to the organic solvent chosen reflects both differences in the bare solvent/water interfacial tension as well as the propensity of the copolymer to aggregate within the organic phase. While instabilities coincident with an approach of the interfacial tension nearly to zero were observed only for copolymers with PEO content greater than 15 wt.%, beyond this point the interfacial behavior and critical concentration needed to trigger surface instability were found to depend only weakly on copolymer composition. PMID:21981970

Zhu, Jintao; Hayward, Ryan C

2012-01-01

247

A test of implicit solvent models on the folding simulation of the GB1 peptide.  

PubMed

To quantify the effects of implicit solvent model on the folding of protein, thermodynamics calculation was performed for the folding of C-terminal hairpin from B1 domain of protein G using AMBER ff96 force field and different implicit solvent models (GB(OBC) and GBn). In the multiple AMBER force fields, ff96 strongly favors the hairpin conformations whereas the other force fields (e.g., ff94 and ff99) favor the helical conformations. In recent studies ff96 was found to be better balanced for various secondary structures than other force fields. The two implicit solvent models mentioned above were shown to be the most appropriate for beta-hairpin folding [M. S. Shell et al., J. Phys. Chem. B 112, 6878 (2008)]. The free energy landscape as a function of several different reaction coordinates was studied for both solvent models. The comparison of the results from these implicit models shows that the combination of AMBER ff96 with the GB(OBC) model yields stable structures that are in better agreement with experiments and results calculated using the explicit solvent model. PMID:19466868

Shao, Qiang; Yang, Lijiang; Gao, Yi Qin

2009-05-21

248

What makes critical-solvent processes work  

SciTech Connect

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.

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

1984-06-01

249

Firing of pulverized solvent refined coal  

DOEpatents

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.

Lennon, Dennis R. (Allentown, PA); Snedden, Richard B. (McKeesport, PA); Foster, Edward P. (Macungie, PA); Bellas, George T. (Library, PA)

1990-05-15

250

Switchable solvents and methods of use thereof  

DOEpatents

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.

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

2014-04-29

251

Switchable solvents and methods of use thereof  

DOEpatents

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.

Jessop, Philip G. (Kingston, CA); Eckert, Charles A. (Atlanta, GA); Liotta, Charles L. (Atlanta, GA); Heldebrant, David J. (Richland, WA)

2011-07-19

252

Conformal Fermi Coordinates  

E-print Network

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.

Liang Dai; Enrico Pajer; Fabian Schmidt

2015-02-06

253

Ion Exchange and Solvent Extraction: Supramolecular Aspects of Solvent Exchange Volume 21  

SciTech Connect

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 inverse micelles swollen with water molecules. Extraction systems involving long-chain cations such as alkylammonium species or long-chain anions such as sulfonates or carboxylates proved especially prone to extensive aggregate formation. The related phenomenon of third-phase formation in SX systems, long misunderstood, is now yielding to spectroscopic and scattering techniques showing extensive long-range organization. Over the last 50 years, tools for studying the structure and thermodynamics of aggregation have grown increasingly sophisticated, leading to a rich and detailed understanding of what we can now recognize as SC phenomena in SX. In the 1970s and 1980s, the rapid growth of SC elicited a paradigm shift in SX. The influence of SC principles had two major effects on the course of SX research. First, it provided a framework for understanding the supramolecular behavior that was already well appreciated in the field of SX, though earlier without the SC terminology. Second, it provided the conceptual tools to control supramolecular behavior in SX, direct it for intended functionality, and to simplify it. Extraction by designed reagents has been steadily progressing ever since, with commercial applications emerging to successfully validate this approach. With the discovery of crown ethers in the late 1960s, the advancement of extractant design has fruitfully employed the concept of inclusion. While considerable initial progress occurred with such molecules, especially because of their affinity and selectivity for alkali and alkaline earth metals, other molecular platforms such as calixarenes have proven more versatile. Multidentate receptors for partial to full inclusion of cations, anions, ion pairs, as well as neutral species, have now become commonplace for selective extraction. This volume of Ion Exchange and Solvent Extraction examines how the principles of SC are being employed both in advancing the design of new highly selective SX systems and in understanding aggregation phenomena in SX systems. Chapter 1 discusses the nature and definition of SC

Gloe, Karsten [Technischen Universität Dresden] [Technischen Universität Dresden; Tasker, Peter A [ORNL] [ORNL; Oshima, Tatsuya [University of Miyazaki] [University of Miyazaki; Watarai, Hitoshi [Institute for NanoScience Design at Osaka University] [Institute for NanoScience Design at Osaka University; Nilsson, Mikael [University of California, Irvine] [University of California, Irvine

2013-01-01

254

Effect of Ligand Structural Isomerism in Formation of Calcium Coordination Networks  

SciTech Connect

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.

Plonka A. M.; Parise J.; Banerjee, D.

2012-03-28

255

Optimizing injected solvent fraction in stratified reservoirs  

E-print Network

low permeability layers may be scarcely swept at all. Presence or absence of transverse communication between layers can modify overall sweep efficiency. This work is a study of water-solvent injection in stratified reservoirs based on computer...

Moon, Gary Michael

2012-06-07

256

United States Air Force Wipe Solvent Testing  

NASA Technical Reports Server (NTRS)

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.

Hornung, Steven D.; Beeson, Harold D.

2000-01-01

257

Modelling the effect of solvents on carbohydrates  

Technology Transfer Automated Retrieval System (TEKTRAN)

Carbohydrates are polar molecules and their conformational and anomeric equilibrium can be strongly influenced by solvents. This review provides examples of studies addressing different issues of glycochemistry, such as anomeric equilibrium, conformational changes in rings, modelling of inter-residu...

258

Used lubricating oil recycling using hydrocarbon solvents.  

PubMed

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

Hamad, Ahmad; Al-Zubaidy, Essam; Fayed, Muhammad E

2005-01-01

259

SOLVENT EXTRACTION OF ORGANIC WATER POLLUTANTS  

EPA Science Inventory

Based on experiments with model systems of known organic water pollutants and environmental samples, conclusions are reached concerning the best general solvent for extraction and the most appropriate methods for related manipulations. Chloroform, methylene chloride-ether mixture...

260

Implicit solvent methods for free energy estimation.  

PubMed

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

Decherchi, Sergio; Masetti, Matteo; Vyalov, Ivan; Rocchia, Walter

2014-08-25

261

Brayton Solvent Recovery Heat Pump Technology Update  

E-print Network

The Brayton cycle technology was developed to reduce the temperature of gas streams containing solvents in order to condense and recover them. While the use of turbo compressor/expander machinery in conjunction with an energy recuperator...

Enneking, J. C.

262

Biological monitoring of chlorinated hydrocarbon solvents  

SciTech Connect

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.

Monster, A.C.

1986-08-01

263

Process for solvent refining of coal using a denitrogenated and dephenolated solvent  

DOEpatents

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.

Garg, Diwakar (Macungie, PA); Givens, Edwin N. (Bethlehem, PA); Schweighardt, Frank K. (Allentown, PA)

1984-01-01

264

Biofiltration of solvent vapors from air  

SciTech Connect

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.

Oh, Young-sook.

1993-01-01

265

CERT Coordination Center  

NSDL National Science Digital Library

The CERT Coordination Center is part of the Software Engineering Institute at Carnegie Mellon University. Its primary function is to work with industry to identify and eliminate Internet security vulnerabilities. Additionally, the center analyzes business and personal software to find potentially dangerous flaws that could compromise the system, meaning that both corporate and home users can benefit from the information offered on the Web site. There are continual updates of security advisories, survivability guides, and fixes that can help prevent disasters or speed recovery from them. Step-by-step suggestions make finding and implementing an efficient security practice reasonably painless. A wide range of papers and presentations on Internet and computer security research are available for free download.

1997-01-01

266

Coordinating Group report  

SciTech Connect

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.

Not Available

1994-01-01

267

Caustic-Side Solvent Extraction: Chemical and Physical Properties of the Optimized Solvent  

SciTech Connect

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.

Delmau, L.H.

2002-10-08

268

Solvent Extraction and Ion Exchange in Radiochemistry  

NASA Astrophysics Data System (ADS)

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.

Skarnemark, G.

269

Solvent dependent photophysical properties of dimethoxy curcumin.  

PubMed

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 (?f), 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 (?(f)) and fluorescence lifetime (?(f)) of DMC were also measured in different solvents at room temperature. The results indicated that with increasing solvent polarity, ?(f) increased linearly, which has been accounted for the decrease in non-radiative rate by intersystem crossing (ISC) processes. PMID:23314392

Barik, Atanu; Indira Priyadarsini, K

2013-03-15

270

Coordinate transformations in quaternion spaces  

E-print Network

The quaternion spaces can be used to describe the property of electromagnetic field and gravitational field. In the quaternion space, some coordinate transformations can be deduced from the feature of quaternions, including Lorentz transformation and Galilean transformation etc., when the coordinate system is transformed into others. And some coordinate transformations with variable speed of light can be obtained in the electromagnetic field and gravitational field.

Zihua Weng

2009-05-15

271

Cosmology and the weak interaction  

NASA Technical Reports Server (NTRS)

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.

Schramm, David N.

1989-01-01

272

COMPUTER-AIDED SOLVENT DESIGN FOR POLLUTION PREVENTION: PARIS II  

EPA Science Inventory

Solvent substitution is an attractive way of elijminating the use of regulated solvents because it usually does not require major chanages in existing processes, equipment or operations. Successful solvent substitution is dependent on finding solvents that are as effective or be...

273

Scale-up of recovery process for waste solvents  

SciTech Connect

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.

Bohnert, G.W.; Carey, D.A.

1991-02-01

274

Solvent dependence of 7-azaindole dimerization.  

PubMed

We have investigated 7-azaindole (AI) in a variety of solvents including CCl4, CHCl3, CH2Cl2, acetone, CH3CN, and DMSO by femtosecond Raman-induced Kerr effect spectroscopy. In differential low-frequency Kerr spectra between the solutions and the respective neat solvents, vibrational bands of the AI hydrogen-bonding (HB) dimer have been observed at ca. 90 and 105 cm(-1) in CHCl3 and CH2Cl2, as well as CCl4: the standard solvent for the AI dimer. In contrast, a broad monomodal band at ca. 80 cm(-1) characterizes an HB mode between the AI monomer and solvent in acetone, CH3CN, and DMSO. The overdamped Kerr transients in the picosecond region show evidence of both the AI monomer and dimer reorientations in CHCl3, CH2Cl2, acetone, and CH3CN, but only the monomer reorientation has been confirmed in DMSO. The clear intermolecular HB bands have not been observed in acetone, CH3CN, and DMSO because these solvents are sufficiently strong HB acceptors, which form HB AI-solvent complexes, thus preventing quantitative AI dimerization. In addition, it is plausible that the HB band of between AI and solvent obscures the intermolecular bands of the AI dimer when the concentration of the AI dimer is much lower than the AI monomer. For comparison, we have employed NMR to study the concentration-dependent chemical shift of the proton attached to the N at the 7-position of AI and to estimate the dimerization constant: 356, 13.3, 14.7, 0.727, and 0.910 M(-1) in CCl4, CHCl3, CH2Cl2, acetone, and CH3CN, respectively. The femtosecond Raman-induced Kerr effect spectroscopy and NMR results are in good agreement. PMID:24191715

Shirota, Hideaki; Fukuda, Takao; Kato, Tatsuya

2013-12-19

275

Ulysses: UVCS Coordinated Observations  

NASA Technical Reports Server (NTRS)

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.

Suess, S. T.; Poletto, G.; Corti, G.; Simnett, G.; Noci, G.; Romoli, M.; Kohl, J.; Goldstein, B.

1998-01-01

276

[University training for coordinators].  

PubMed

We need an adequate quality level of information between the building design and manufacturing process for Health and Safety in the work site. A fully-developed communication system is needed, for H&S Coordinators, in order to integrate alphanumerical and graphical protocols. The Aim is: (1) to organise information on the building process, keeping communications in function of everyone's needs; (2) to carry out an audit process ensuring that all levels of contractors personnel are implementing the Project of Health and Safety Management Plan effectively; (3) To make all that with a Program Interface relatively simple. The synergy between Safety Manager and Designers generates a system output integrating all sorts of alphanumerical, graphical information and prescriptions. This system output has several targets: (1) to integrate Design and H&S in a specific Data-Base; (2) to define the preconditions of the work phases; (3) to develop the Work Program of Enterprise in function of the Health and Safety Plan in compliance with the contractor site-specific plan; (4) to develop a program process for the audit; (5) to review the contractor's Project for H & S; (6) to manage responsibility; (7) to keep corrective action. PMID:16718930

Gotti, G

2006-01-01

277

Chlorinated solvent replacements recycle/recovery review report  

SciTech Connect

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.

Beal, M.; Hsu, D.; McAtee, R.E.; Weidner, J.R. (EG and G Idaho, Inc., Idaho Falls, ID (United States)); Berg, L.; McCandless, F.P.; Waltari, S.; Peterson, C. (Montana State Univ., Bozeman, MT (United States). Dept. of Chemical Engineering)

1992-08-01

278

The Neural Network In Coordinate Transformation  

NASA Astrophysics Data System (ADS)

In international literature, Coordinate operations is divided into two categories. They are coordinate conversion and coordinate transformation. Coordinates converted from coordinate system A to coordinate system B in the same datum (mean origine, scale and axis directions are same) by coordinate conversion. There are two different datum in coordinate transformation. The basis of each datum to a different coordinate reference system. In Coordinate transformation, coordinates are transformed from coordinate reference system A to coordinate referance system B. Geodetic studies based on physical measurements. Coordinate transformation needs identical points which were measured in each coordinate reference system (A and B). However it is difficult (and need a big reserved budget) to measure in some places like as top of mountain, boundry of countries and seaside. In this study, this sample problem solution was researched. The method of learning which is one of the neural network methods, was used for solution of this problem.

Urusan, Ahmet Yucel

2011-12-01

279

A protein molecule in an aqueous mixed solvent: Fluctuation theory outlook  

NASA Astrophysics Data System (ADS)

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.

Shulgin, Ivan L.; Ruckenstein, Eli

2005-08-01

280

Organic Solvent-Tolerant Bacterium Which Secretes an Organic Solvent-Stable Proteolytic Enzyme  

PubMed Central

A bacterial strain which can be grown in a medium containing organic solvents and can secrete a proteolytic enzyme was isolated and identified as Pseudomonas aeruginosa. The strain was derived by the following two-step procedures: high proteolytic enzyme producers were first isolated by the usual method, and then the organic solvent-tolerant microorganism was selected from these high-rate proteolytic enzyme producers. The proteolytic activity of the supernatant of the culture was stable in the presence of various organic solvents. The stability of the enzyme in the presence of organic solvents, of which the values of the logarithm of the partition coefficient (log P) were equal to or more than 3.2, was almost the same as that in the absence of organic solvents. It is expected that both the solvent-tolerant microorganism and the solvent-stable enzyme produced by this strain can be used as catalysts for reactions in the presence of organic solvents. PMID:16535181

Ogino, H.; Yasui, K.; Shiotani, T.; Ishihara, T.; Ishikawa, H.

1995-01-01

281

Removal of traces of pentachlorophenol from aqueous acidic solutions by solvent extraction and solvent sublation  

SciTech Connect

The removal of pentachlorophenol (a hydrophobic compound of low vapor pressure) from aqueous acidic solutions was studied using solvent sublation (a surface chemical technique) and solvent extraction. Both methods gave appreciable removals in highly acidic solutions (pH = 2.5), but solvent sublation had the added advantage of minimal phase contact of the organic solvent with water and increased removals under certain circumstances. Solvent sublation was also found to be more effective than conventional fine bubble aeration. The removal of pentachlorophenol (PCP) was considerably smaller at pH's near the pK/sub a/ of PCP. PCP removal by solvent sublation was enhanced by increasing ionic strength and also by the presence of small amounts of an ionic surfactant in the aqueous phase. The technique of solvent sublation was tried on an actual wastewater sample from a wood preserving industry. pH adjustment, removal of suspended solids, addition of sodium chloride, and subsequent solvent sublation into mineral oil reduced the PCP concentration in the aqueous waste by 99.7%.

Valsaraj, K.T.; Springer, C.

1986-01-01

282

Solvent tolerant marine bacterium Bacillus aquimaris secreting organic solvent stable alkaline cellulase  

Microsoft Academic Search

The organic solvent tolerant bacteria with their physiological abilities to decontaminate the organic pollutants have potentials to secrete extracellular enzymes of commercial importance. Of the 19 marine bacterial isolates examined for their solvent tolerance at 10vol.% concentration, one had the significant tolerance and showed a relative growth yield of 86% for acetone, 71% for methanol, 52% for benzene, 35% for

Nitin Trivedi; Vishal Gupta; Manoj Kumar; Puja Kumari; C. R. K. Reddy; Bhavanath Jha

2011-01-01

283

Solvent refined lignite and solvent refined coal structural features. Computerized methodology development. [7 refs  

Microsoft Academic Search

Solvent refined lignite (SRL) and bituminous coal (SRC) are by definition very nonvolatile substances, but are quite soluble in certain organic solvents. Thus, MS-computer techniques are not very applicable for deriving structural information. However, many other powerful spectroscopic techniques are applicable. An attempt is being made to computerize an approach for gaining a great deal of information rapidly about average

N. Woolsey; R. Baltisberger; K. Klabunde; V. Stenberg; R. Kaba

1976-01-01

284

Weak gravitational lensing with DEIMOS  

Microsoft Academic Search

We introduce a novel method for weak-lensing measurements, which is based on a mathematically exact deconvolution of the moments of the apparent brightness distribution of galaxies from the telescope's point spread function (PSF). No assumptions on the shape of the galaxy or the PSF are made. The (de)convolution equations are exact for unweighted moments only, while in practice a compact

P. Melchior; M. Viola; B. M. Schäfer; M. Bartelmann

2011-01-01

285

40 CFR Table 3 to Subpart Mmmm of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends  

Code of Federal Regulations, 2010 CFR

...2010-07-01 true Default Organic HAP Mass Fraction for Solvents and Solvent Blends...Subpart MMMM of Part 63—Default Organic HAP Mass Fraction for Solvents and Solvent Blends You may use the mass fraction values in the following...

2010-07-01

286

40 CFR Table 5 to Subpart Qqqq of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends  

Code of Federal Regulations, 2010 CFR

...2010-07-01 true Default Organic HAP Mass Fraction for Solvents and Solvent Blends...Subpart QQQQ of Part 63—Default Organic HAP Mass Fraction for Solvents and Solvent Blends You may use the mass fraction values in the following...

2010-07-01

287

40 CFR Table 3 to Subpart Rrrr of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends  

Code of Federal Regulations, 2010 CFR

...2010-07-01 true Default Organic HAP Mass Fraction for Solvents and Solvent Blends...Subpart RRRR of Part 63—Default Organic HAP Mass Fraction for Solvents and Solvent Blends You may use the mass fraction values in the following...

2010-07-01

288

40 CFR Table 6 to Subpart Kkkk of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends  

Code of Federal Regulations, 2011 CFR

...2009-07-01 true Default Organic HAP Mass Fraction for Solvents and Solvent Blends...Subpart KKKK of Part 63—Default Organic HAP Mass Fraction for Solvents and Solvent Blends You may use the mass fraction values in the following...

2011-07-01

289

40 CFR Table 3 to Subpart Pppp of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends  

Code of Federal Regulations, 2010 CFR

...2010-07-01 true Default Organic HAP Mass Fraction for Solvents and Solvent Blends...Subpart PPPP of Part 63—Default Organic HAP Mass Fraction for Solvents and Solvent Blends You may use the mass fraction values in the following...

2010-07-01

290

40 CFR Table 5 to Subpart Qqqq of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends  

Code of Federal Regulations, 2011 CFR

...2009-07-01 true Default Organic HAP Mass Fraction for Solvents and Solvent Blends...Subpart QQQQ of Part 63—Default Organic HAP Mass Fraction for Solvents and Solvent Blends You may use the mass fraction values in the following...

2011-07-01

291

40 CFR Table 6 to Subpart Kkkk of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends  

Code of Federal Regulations, 2010 CFR

...2010-07-01 true Default Organic HAP Mass Fraction for Solvents and Solvent Blends...Subpart KKKK of Part 63—Default Organic HAP Mass Fraction for Solvents and Solvent Blends You may use the mass fraction values in the following...

2010-07-01

292

40 CFR Table 3 to Subpart Pppp of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends  

Code of Federal Regulations, 2011 CFR

...2009-07-01 true Default Organic HAP Mass Fraction for Solvents and Solvent Blends...Subpart PPPP of Part 63—Default Organic HAP Mass Fraction for Solvents and Solvent Blends You may use the mass fraction values in the following...

2011-07-01

293

40 CFR Table 3 to Subpart Mmmm of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends  

Code of Federal Regulations, 2011 CFR

...2009-07-01 true Default Organic HAP Mass Fraction for Solvents and Solvent Blends...Subpart MMMM of Part 63—Default Organic HAP Mass Fraction for Solvents and Solvent Blends You may use the mass fraction values in the following...

2011-07-01

294

40 CFR Table 3 to Subpart IIIi of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends  

Code of Federal Regulations, 2011 CFR

...2009-07-01 true Default Organic HAP Mass Fraction for Solvents and Solvent Blends...Subpart IIII of Part 63—Default Organic HAP Mass Fraction for Solvents and Solvent Blends You may use the mass fraction values in the following...

2011-07-01

295

40 CFR Table 3 to Subpart Nnnn of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends  

Code of Federal Regulations, 2011 CFR

...2009-07-01 true Default Organic HAP Mass Fraction for Solvents and Solvent Blends...Subpart NNNN of Part 63—Default Organic HAP Mass Fraction for Solvents and Solvent Blends You may use the mass fraction values in the following...

2011-07-01

296

Sorption phenomena of organic solvents in polymers: Part II  

Microsoft Academic Search

In this work we use the vapor-sorption equilibrium data to show the degree of solvent upturn in each solvent–polymer system. For this purpose, sixty-one isothermal data sets for forty copolymer+solvent binaries and for fourteen of their parent homopolymer+solvent binaries have been used in the temperature range of 23.5–80°C. Solvents studied are acetone, acetonitrile, 1-butanol, 1,2-dichloroethane, chloroform, cyclohexane, hexane, methanol, octane,

Fatemeh Sabzi; Ali Boushehri

2005-01-01

297

[Enzymatic catalysis in non-aqueous solvents].  

PubMed

It is well known that non-aqueous enzymatic catalysis has emerged as an important area of enzyme engineering with the advantages of higher substrate solubility, increased stereoselectivity, modified substrate specificity and suppression of unwanted water-dependent side reactions. As a result, non-aqueous enzymatic catalysis has been applied in the biocatalytic synthesis of important pharmaceuticals and nutriceuticals. With the advancement of non-aqueous enzymatic catalysis in recent years, the efforts have been centered on the discovery and modification of solvent-tolerant biocatalysts for non-aqueous environments. Additionally, with the inevitable trends of green chemistry and sustainable development, green solvents have been utilized for increased number of enzymatic reactions to replace conventional organic solvents. In this review, modification, immobilization and mutagenesis of various enzymes for non-aqueous catalysis are discussed. Recent progress of non-aqueous enzymatic catalysis in solvent-free environments, reverse micelles, supercritical liquid and ionic liquid are also presented. In particular, while direct evolution, high-throughput screening and site-directed mutagenesis are combined as powerful tools for protein engineering, vapor/solid/ice water mixture, sticky solid-state liquid crystal and high density salt suspension are the future directions for solvent engineering in order to broaden the utility and elevate the efficiency of non-aqueous enzymatic catalysis. PMID:20352953

Wang, Lili; Chen, Yijun

2009-12-01

298

Solvent extraction of phenols from water  

SciTech Connect

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.

Greminger, D.C.; Burns, G.P.; Lynn, S.; Hanson, D.H.; King, C.J.

1980-02-01

299

Note on (weak) Gorenstein global dimensions  

Microsoft Academic Search

In this note we characterize the (resp., weak) Gorenstein global dimension for an arbitrary ring. Also, we extend the well-known Hilbert's syzygy Theorem to the weak Gorenstein global dimension and we study the weak Gorenstein homological dimensions of direct product of rings, which gives examples of non-coherent rings of finite Gorenstein dimensions $>0$ and infinite classical weak dimension.

Najib Mahdou; Mohammed Tamekkante

2009-01-01

300

Panhandle Region Transportation Coordination Study  

E-print Network

......................................................................................................................... 2-5 Health and Human Services Organizations ................................................................................. 2-9 History of Regional Coordination of Public Transportation .................................................... 2...; and ? Coordinate transportation service access beyond those served by one agency or organization within a community. For example, a non-profit agency receiving funding through NF could not limit the services it provides to its own clientele. These services...

Panhandle Regional Transportation Advisory Group

301

Scalable Coordination in Sensor Networks  

Microsoft Academic Search

Network sensorsthose that coordinate amongst themselvesto achieve a larger sensing taskwill revolutionizeinformation gathering and processing both in urban environmentsand in inhospitable terrain. The sheer numbers ofthese sensors and the expected dynamics in these environmentspresent unique challenges in the design of unattendedautonomous sensor networks. These challenges lead us tohypothesize that sensor network coordination applicationsmay need to be structured dierently from...

Deborah Estrin; John Heidemann; Ramesh Govindan

1999-01-01

302

Fuzzy coordinator in control problems  

NASA Technical Reports Server (NTRS)

In this paper a hierarchical control structure using a fuzzy system for coordination of the control actions is studied. The architecture involves two levels of control: a coordination level and an execution level. Numerical experiments will be utilized to illustrate the behavior of the controller when it is applied to a nonlinear plant.

Rueda, A.; Pedrycz, W.

1992-01-01

303

Coordinate Dependence of Variability Analysis  

PubMed Central

Analysis of motor performance variability in tasks with redundancy affords insight about synergies underlying central nervous system (CNS) control. Preferential distribution of variability in ways that minimally affect task performance suggests sophisticated neural control. Unfortunately, in the analysis of variability the choice of coordinates used to represent multi-dimensional data may profoundly affect analysis, introducing an arbitrariness which compromises its conclusions. This paper assesses the influence of coordinates. Methods based on analyzing a covariance matrix are fundamentally dependent on an investigator's choices. Two reasons are identified: using anisotropy of a covariance matrix as evidence of preferential distribution of variability; and using orthogonality to quantify relevance of variability to task performance. Both are exquisitely sensitive to coordinates. Unless coordinates are known a priori, these methods do not support unambiguous inferences about CNS control. An alternative method uses a two-level approach where variability in task execution (expressed in one coordinate frame) is mapped by a function to its result (expressed in another coordinate frame). An analysis of variability in execution using this function to quantify performance at the level of results offers substantially less sensitivity to coordinates than analysis of a covariance matrix of execution variables. This is an initial step towards developing coordinate-invariant analysis methods for movement neuroscience. PMID:20421930

Sternad, Dagmar; Park, Se-Woong; Müller, Hermann; Hogan, Neville

2010-01-01

304

Chameleon Graphing: The Coordinate Plane  

NSDL National Science Digital Library

This Web unit introduces the coordinate plane with the help of Sam the Chameleon, who illustrates how to find points on a number line and graph points in the coordinate plane. A link to a Java applet for graphing with Sam is included.

Ursula Whitcher

2000-01-01

305

Green-solvent-processed molecular solar cells.  

PubMed

High-efficiency bulk heterojunction (BHJ) organic solar cells with power conversion efficiencies of more than 5?% can be fabricated using the green solvent 2-MeTHF. The active layers comprise a blend of a molecular semiconductor donor with intermediate dimensions (X2) and the soluble fullerene derivative [6,6]-phenyl-C61 -butyricacidoctylester (PC61 BC8 ). A switch of the processing solvent from chloroform to 2-MeTHF leads to no negative impacts on the morphology and charge-transport properties of optimally performing BHJ films. Examinations by absorption spectroscopy, atomic force microscopy, and grazing incidence wide-angle X-ray scattering reveal no significant modification of morphology. These results show that green solvents can be excellent alternatives for large-area printing of high-performance organic photovoltaics (OPVs) and thus open new opportunities for sustainable mass production of organic solar cells and other optoelectronic devices. PMID:25389005

Chen, Xiaofen; Liu, Xiaofeng; Burgers, Mark A; Huang, Ye; Bazan, Guillermo C

2014-12-22

306

Proton transfer reactions of 4'-chloro substituted 3-hydroxyflavone in solvents and aqueous micelle solutions.  

PubMed

Flavonol 4'-chloro,3-hydroxyflavone (Cl-3HF) has been investigated in solvents of varying polarity and hydrogen-bonding capacity as well as in aqueous micelle solutions. Quantum chemical calculations indicate that although the Cl-atom at the 4'-position of the 2-phenyl ring weakly perturbs the electron distribution of the parent 3-hydroxyflavone, the nuclear framework remains largely intact, and excited state intra-molecular proton-transfer (ESIPT) is feasible. The ESIPT process in both polar solvents and micelles was found to be fast and irreversible, with remarkably long time-constants of several tens of picoseconds. This dramatic inhibition of the ESIPT rate (which is intrinsically a sub-picosecond event) could be rationalized in terms of the emergence of complexes between the solvent and the enol form of Cl-3HF, whose dynamics is coupled to the relatively slow dynamics of inter-molecular hydrogen bonds. In the micelle solutions, spectroscopic data establish that the guest Cl-3HF molecules localized almost exclusively at the polar exterior shell, where they experienced a nearly uniform local environment similar to that in moderately polar solvents. Thus, the Cl-3HF molecules tend to avoid the non-polar core of the micelles, in spite of being strongly hydrophobic themselves. This apparently unusual observation is explained by the formation of inter-molecularly hydrogen-bonded complexes between the guest Cl-3HF and the water molecules tethered to the polar shells of the micelles. PMID:24671355

Ghosh, Deborin; Pradhan, Anup Kumar; Mondal, Samiran; Begum, N A; Mandal, Debabrata

2014-05-14

307

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

NASA Astrophysics Data System (ADS)

A series of lanthanide-organic complexes based on polyoxometalates (POMs) [Ln2(DNBA)4(DMF)8][W6O19] (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 [W6O19]2- and dimeric [Ln2(DNBA)4(DMF)8]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 [Ln2(DNBA)4]2+ remains unchanged in solution. The conservation of red luminescence is attributed to the maintenance of the aggregated state structures of dimeric cations.

Tang, Qun; Liu, Shu-Xia; Liang, Da-Dong; Ma, Feng-Ji; Ren, Guo-Jian; Wei, Feng; Yang, Yuan; Li, Cong-Cong

2012-06-01

308

Thin-film evaporator recovers solvents continuously  

SciTech Connect

Reclaimed Energy Company, Inc., Connersville, IN, receives waste generated from a wide variety of industrial applications which include paint, printing and degreasing companies. The wastes are stored in separate tanks and then distilled in batches (pot distillation). The recovered solvents can be returned to the originator. The residue, left after the solvents are distilled, is disposed of using an environmentally safe, economical procedure. The company worked with an engineering and fabrication firm to develop a continuous processing system that employs a mechanically agitated thin-film evaporator to distill the solvents. Successful performance of the evaporator was ensured by processing samples of solvents through the evaporator manufacturer's pilot plant facilities before the full-sized system was designed. Reclaimed Energy Company, Inc., has realized a number of advantages by going from pot distillation to the agitated thin-film evaporator system to distill solvents. First, distillation no longer generates wastewater and no water is added to the distillate. Second, a feed tank of any size can be hooked up and run on a continuous basis until that tank is empty. Third, the residue can be kept fluid and is free of water so that it can be sold as a chemical fuel. Fourth, the high-boiling solvents can be distilled under vacuum, reducing thermal degradation and improving operating efficiency. Fifth, the residence time in the evaporator is extremely short. The extensive automatic controls installed on the skid make the equipment very versatile. The evaporator can be used to run many different products with a minimum of changes requiring operator attention.

Roembke, R.; Mode, J.; Hodel, A.E.

1985-11-01

309

Weak values and weak coupling maximizing the output of weak measurements  

NASA Astrophysics Data System (ADS)

In a weak measurement, the average output of a probe that measures an observable Aˆ of a quantum system undergoing both a preparation in a state ? and a postselection in a state E is, to a good approximation, a function of the weak value Aw=Tr[EAˆ?]/Tr[E?], a complex number. For a fixed coupling ?, when the overlap Tr[E?] is very small, Aw diverges, but 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 Aw and ?, 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 cannot exceed the initial uncertainty ?o in the observable oˆ, we provide an upper limit for the more general case, and a strategy to obtain ??o.

Di Lorenzo, Antonio

2014-06-01

310

Weak values and weak coupling maximizing the output of weak measurements  

E-print Network

In a weak measurement, the average output $\\langle o\\rangle$ of a probe that measures an observable $\\hat{A}$ of a quantum system undergoing both a preparation in a state $\\rho_i$ and a postselection in a state $E_\\mathrm{f}$ is, to a good approximation, a function of the weak value $A_w=\\mathrm{Tr} [E_f \\hat{A} \\rho_i]/\\mathrm{Tr}[E_f\\rho_i]$, a complex number. For a fixed coupling $\\lambda$, when the overlap $\\mathrm{Tr}[E_f\\rho_i]$ is very small, $A_w$ diverges, but $\\langle o\\rangle$ 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 $A_w$ and $\\lambda$, 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 Schr\\"{o}dinger-Robertson uncertainty relation, we demonstrate that, in an important case, the amplification $\\langle o\\rangle$ cannot exceed the initial uncertainty $\\sigma_o$ in the observable $\\hat{o}$, we provide an upper limit for the more general case, and a strategy to obtain $\\langle o\\rangle\\gg \\sigma_o$.

Antonio Di Lorenzo

2014-05-01

311

Solvent-resistant microporous polymide membranes  

DOEpatents

An asymmetric microporous membrane with exceptional solvent resistance and highly desirable permeability is disclosed. The membrane is made by a solution-casting or solution-spinning process from a copolyamic acid comprising the condensation reaction product in a solvent of at least three reactants selected from certain diamines and dianhydrides and post-treated to imidize and in some cases cross-link the copolyamic acid. The membrane is useful as an uncoated membrane for ultrafiltration, microfiltration, and membrane contactor applications, or may be used as a support for a permselective coating to form a composite membrane useful in gas separations, reverse osmosis, nanofiltration, pervaporation, or vapor permeation.

Miller, W.K.; McCray, S.B.; Friesen, D.T.

1998-03-10

312

Solvent-resistant microporous polymide membranes  

DOEpatents

An asymmetric microporous membrane with exceptional solvent resistance and highly desirable permeability is disclosed. The membrane is made by a solution-casting or solution-spinning process from a copolyamic acid comprising the condensation reaction product in a solvent of at least three reactants selected from certain diamines and dianhydrides and post-treated to imidize and in some cases cross-link the copolyamic acid. The membrane is useful as an uncoated membrane for ultrafiltration, microfiltration, and membrane contactor applications, or may be used as a support for a permselective coating to form a composite membrane useful in gas separations, reverse osmosis, nanofiltration, pervaporation, or vapor permeation.

Miller, Warren K. (Bend, OR); McCray, Scott B. (Bend, OR); Friesen, Dwayne T. (Bend, OR)

1998-01-01

313

Coordination polymers of uranium(iv) terephthalates.  

PubMed

A series of tetravalent uranium terephthalates has been solvothermally synthesized in the solvent N,N-dimethylformamide (DMF) at temperature 100-150 °C with different water amounts. Composition diagrams have been determined for the U(4+) metallic cation in the presence of terephthalic acid, and their crystal structures revealed the occurrence of two- or three-dimensional coordination polymers. In the absence of water, a mixture of two polytypes T-U2Cl2(bdc)3(DMF)4 () and M-U2Cl2(bdc)3(DMF)4 () has been identified at low temperature (100-110 °C) for bdc/U = 1-4 (bdc = terephthalate linker). Their structures are built up from isolated uranium centers in nine-fold coordination, surrounded by 6 carboxyl oxygen atoms, 2 oxygen atoms coming from DMF molecules and one chlorine atom. The uranium cations are linked to each other through the bdc ligand in order to generate a 3D framework. By increasing the temperature (130-150 °C), a layered like compound has been isolated, U2(bdc)4(DMF)4 (). It is composed of discrete actinide centers in ten-fold coordination, with 8 carboxyl oxygen atoms and 2 oxygen atoms from DMF molecules. The connection of the UO10 units with the bdc linkers generates 2D sheets. When a controlled amount of water is added to the reaction medium, the crystallization of the UiO-66-like U6O4(OH)4(H2O)6(bdc)6·10DMF solid (containing a hexanuclear sub-unit) is observed for temperature 110-120 °C and the H2O/U molar ratio in the range of 2-10. At higher temperature (140-150 °C), a distinct phase appeared, U2O2(bdc)2(DMF) (), which consists of infinite chains of uranium centers, linked to each other via the bdc ligands. Higher water contents led to the formation of urania UO2. PMID:25428593

Falaise, Clément; Assen, Ayalew; Mihalcea, Ionut; Volkringer, Christophe; Mesbah, Adel; Dacheux, Nicolas; Loiseau, Thierry

2015-01-28

314

How the quantum efficiency of a highly emissive binuclear copper complex is enhanced by changing the processing solvent.  

PubMed

Polymorphism is often linked to the choice of processing solvents. Packing effects or the preference of one certain conformer as possible causes of this phenomenon are strongly dependent on solvents and especially on their polarity. Even in amorphous solids, the microstructure can be controlled by the choice of solvents. Polymorphs or amorphous solids featuring different packing densities can exhibit different properties in terms of stability or optical effects. The influence of these effects on a binuclear, strongly luminescent copper(I) complex was investigated. Many possible applications for luminescent, amorphous coordination compounds, such as organic light-emitting diodes, sensors, and organic lasers, rely on photophysical properties like quantum efficiency to be repeatable. The effect of processing solvents in this context is often underestimated, but very relevant for utilization in device manufacturing and should therefore be understood more deeply. In this work, theoretical derivations, DFT calculations, X-ray-diffraction, photoluminescence spectroscopy, and the time-dependent single-photon-counting-technique (TDSPC) were used to understand this phenomenon more deeply. The influence of five different solvents on Cu2I2(MePyrPHOS)3 was probed. This resulted in a modulation of the photoluminescence quantum yield ? between 0.5 and 0.9 in amorphous solid state. A new polymorph of the material with slightly reduced values for ? has been identified. The reduced efficiency could be correlated with a higher porosity and a reduced packing density. Dense packing reduces nonradiative decay by geometrical fixation and thus increases the quantum efficiency. The existence of similar effects on aluminum and iridium compounds has been confirmed by application of different processing solvents on Alq3 and Ir(ppy)3. These results show that a tuning of the efficiency of a emissive metal complexes by choosing a proper processing solvent is possible. If highly efficient materials for practical applications are desired, an evaluation of multiple solvents has to be considered. PMID:23373754

Volz, Daniel; Nieger, Martin; Friedrichs, Jana; Baumann, Thomas; Bräse, Stefan

2013-03-01

315

Global Superdiffusion of Weak Chaos  

E-print Network

A class of kicked rotors is introduced, exhibiting accelerator-mode islands (AIs) and {\\em global} superdiffusion for {\\em arbitrarily weak} chaos. The corresponding standard maps are shown to be exactly related to generalized web maps taken modulo an ``oblique cylinder''. Then, in a case that the web-map orbit structure is periodic in the phase plane, the AIs are essentially {\\em normal} web islands folded back into the cylinder. As a consequence, chaotic orbits sticking around the AI boundary are accelerated {\\em only} when they traverse tiny {\\em ``acceleration spots''}. This leads to chaotic flights having a quasiregular {\\em steplike} structure. The global weak-chaos superdiffusion is thus basically different in nature from the strong-chaos one in the usual standard and web maps.

Itzhack Dana

2003-10-20

316

The weak scale from BBN  

NASA Astrophysics Data System (ADS)

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.

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

2014-12-01

317

Solvent and solvent isotope effects on the vibrational cooling dynamics of a DNA base derivative.  

PubMed

Vibrational cooling by 9-methyladenine was studied in a series of solvents by femtosecond transient absorption spectroscopy. Signals at UV and near-UV probe wavelengths were assigned to hot ground state population created by ultrafast internal conversion following electronic excitation by a 267 nm pump pulse. A characteristic time for vibrational cooling was determined from bleach recovery signals at 250 nm. This time increases progressively in H2O (2.4 ps), D2O (4.2 ps), methanol (4.5 ps), and acetonitrile (13.1 ps), revealing a pronounced solvent effect on the dissipation of excess vibrational energy. The trend also indicates that the rate of cooling is enhanced in solvents with a dense network of hydrogen bonds. The faster rate of cooling seen in H2O vs D2O is noteworthy in view of the similar hydrogen bonding and macroscopic thermal properties of both liquids. We propose that the solvent isotope effect arises from differences in the rates of solute-solvent vibrational energy transfer. Given the similarities of the vibrational friction spectra of H2O and D2O at low frequencies, the solvent isotope effect may indicate that a considerable portion of the excess energy decays by exciting relatively high frequency (>/=700 cm-1) solvent modes. PMID:17910423

Middleton, Chris T; Cohen, Boiko; Kohler, Bern

2007-10-25

318

Factors affecting high-pressure solvent extraction (accelerated solvent extraction) of additives from polymers.  

PubMed

Irganox 1010 (pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)] propionate) is successfully extracted from polypropylene using solvents at high temperatures and pressures in a homemade accelerated solvent extraction system. For example, using freeze-ground polymer, 90% extraction is possible within 5 min with 2-propanol at 150 °C. Extraction curves for 2-propanol and acetone fit well to the "hot ball" model, previously developed for supercritical fluid extraction. Diffusion coefficients are determined for extractions with 2-propanol, acetone, and cyclohexane over a range of temperatures, and the activation energies for the diffusion are 134, 107, and 61 kJ mol(-)(1), respectively. The lower figure for acetone and cyclohexane indicates that these solvents swell the polymer more than does 2-propanol. The polymer dissolves in the solvent at too high a temperature, which causes blockage of the transfer lines. For maximum extraction rates, the highest temperature for each solvent that avoids dissolution of the polymer should be used. The use of mixed solvents is investigated and shows advantages in some cases, with the aim of producing a solvent that will swell the polymer but not dissolve it. PMID:21651286

Vandenburg, H J; Clifford, A A; Bartle, K D; Zhu, S A; Carroll, J; Newton, I D; Garden, L M

1998-05-01

319

Keep meaning in conversational coordination  

PubMed Central

Coordination is a widely employed term across recent quantitative and qualitative approaches to intersubjectivity, particularly approaches that give embodiment and enaction central explanatory roles. With a focus on linguistic and bodily coordination in conversational contexts, I review the operational meaning of coordination in recent empirical research and related theorizing of embodied intersubjectivity. This discussion articulates what must be involved in treating linguistic meaning as dynamic processes of coordination. The coordination approach presents languaging as a set of dynamic self-organizing processes and actions on multiple timescales and across multiple modalities that come about and work in certain domains (those jointly constructed in social, interactive, high-order sense-making). These processes go beyond meaning at the level that is available to first-person experience. I take one crucial consequence of this to be the ubiquitously moral nature of languaging with others. Languaging coordinates experience, among other levels of behavior and event. Ethical effort is called for by the automatic autonomy-influencing forces of languaging as coordination. PMID:25520693

Cuffari, Elena C.

2014-01-01

320

Solvent tunable optical properties of a polymerized vinyl- and thienyl-substituted ionic liquid.  

SciTech Connect

Thermal free radical polymerization of a self-assembled, bifunctional imidazolium-based ionic liquid (IL) monomer bearing both vinyl and thienyl groups is reported. FT-IR spectroscopy proves that the polymerization occurs through both the vinyl and thienyl groups. The polymer is resistant to swelling in water and common organic solvents. The as-synthesized polymer can be readily chemically doped and de-doped. Small-angle X-ray scattering studies indicate that the dried polymer adopts a weakly ordered lamellar structure. The p-doped, ethanol-solvated polymer undergoes a structural conversion to a nonlamellar phase. The absorption and photoluminescence spectra can be modulated in both the neutral (thiophene) and p-doped states depending on whether the polymer is dry or ethanol-solvated. The results demonstrate the possibility of incorporating solvent responsive optical characteristics in a {pi}-conjugated polymer.

Becht, G. A.; Lee, S.; Seifert, S.; Firestone, M. A.

2010-09-16

321

Weak Gravitational Lensing by Voids  

E-print Network

We consider the prospects for detecting weak gravitational lensing by underdensities (voids) in the large-scale matter distribution. We derive the basic expressions for magnification and distortion by spherical voids. Clustering of the background sources and cosmic variance are the main factors which limit in principle the detection of lensing by voids. We conclude that only voids with radii larger than $\\sim 100$ \\hm have lensing signal to noise larger than unity.

Luca Amendola; Joshua A. Frieman; Ioav Waga

1998-11-29

322

Quark mixing in weak interactions  

Microsoft Academic Search

The status of the quark mixing in weak interaction is reviewed. The 3×3 quark mixing matrix for the three left-handed doublet model is analyzed using various experimental information involving strange, charmed, and b-flavored particles. Its interplay with nonleptonic decays, implication on neutral particle-antiparticle mixing and CP violation in heavy quark systems, and the possible origin of the quark mixing from

Ling-Lie Chau

1983-01-01

323

A Weakly Intuitionistic Quantum Logic  

E-print Network

In this paper we motivate and study the possibility of an intuitionistic quantum logic. An explicit investigation of the application of the theory of Bruns and Lakser on distributive hulls on traditional quantum logic (as suggested in [Coe]) leads us to a small modification of this scheme. In this way we obtain a weak Heyting algebra (cf. [CJ]) for describing the language of quantum mechanics.

Ronnie Hermens

2010-09-13

324

A Survey of Weak Instruments and Weak Identification in Generalized Method of Moments  

Microsoft Academic Search

Weak instruments arise when the instruments in linear instrumental variables (IV) regression are weakly correlated with the included endogenous variables. In generalized method of moments (GMM), more generally, weak instruments correspond to weak identification of some or all of the unknown parameters. Weak identification leads to GMM statistics with nonnormal distributions, even in large samples, so that conventional IV or

James H. Stock; Jonathan H. Wright; Motohiro Yogo

2002-01-01

325

Weak Interactions in Atoms Nuclear Anapole Moment Weak Coupling Constants Nuclear Anapole Moment  

E-print Network

Weak Interactions in Atoms Nuclear Anapole Moment Weak Coupling Constants Nuclear Anapole Moment;Weak Interactions in Atoms Nuclear Anapole Moment Weak Coupling Constants Plan of the talk Weak Interactions in Atoms Charged and Neutral Currents. Effective P-odd Hamiltonian Nuclear Anapole Moment

Pines, Alexander

326

DEGRADED TBP SOLVENT REGENERATION TECHNOLOGY USING BUTYLAMINE AS A SOLVENT WASHING TO REDUCE SOLID SALT WASTE  

SciTech Connect

Normal butylamine compounds are studied as salt-free wash reagents for degraded solvent used in PUREX process in spent fuel reprocessing. The solvent wash tests were carried out with two types of butylamine compounds, n-butylamine oxalate and n-butylamine bicarbonate, by counter-current mode using a small size mixer-settler composed of two 4-stage wash steps. Di-n-butyl phosphoric acid (HDBP), the main degradation product from TBP, was removed from real degraded solvent with decontamination factor of 2.5 {approx} 7.9. The study on electrolytic decomposition of butylamine compounds was also conducted for waste treatment.

Asakura, T.; Itoh, Y.; Hotoku, S.; Morita, Y.; Uchiyama, G.

2003-02-27

327

Incorporation of the TIP4P water model into a continuum solvent for computing solvation free energy  

NASA Astrophysics Data System (ADS)

The continuum solvent model is one of the commonly used strategies to compute solvation free energy especially for large-scale conformational transitions such as protein folding or to calculate the binding affinity of protein-protein/ligand interactions. However, the dielectric polarization for computing solvation free energy from the continuum solvent is different than that obtained from molecular dynamic simulations. To mimic the dielectric polarization surrounding a solute in molecular dynamic simulations, the first-shell water molecules was modeled using a charge distribution of TIP4P in a hard sphere; the time-averaged charge distribution from the first-shell water molecules were estimated based on the coordination number of the solute, and the orientation distribution of the first-shell waters and the intermediate water molecules were treated as that of a bulk solvent. Based on this strategy, an equation describing the solvation free energy of ions was derived.

Yang, Pei-Kun

2014-10-01

328

Gas separation by composite solvent-swollen membranes  

DOEpatents

There is disclosed a composite immobulized liquid membrane of a solvent-swollen polymer and a microporous organic or inorganic support, the solvent being at least one highly polar solvent containing at least one nitrogen, oxygen, phosphorous or sulfur atom, and having a boiling point of at least 100.degree. C. and a specified solubility parameter. The solvent or solvent mixture is homogeneously distributed through the solvent-swollen polymer from 20% to 95% by weight. The membrane is suitable for acid gas scrubbing and oxygen/nitrogen separation.

Matson, Stephen L. (Harvard, MA); Lee, Eric K. L. (Acton, MA); Friesen, Dwayne T. (Bend, OR); Kelly, Donald J. (Bend, OR)

1989-01-01

329

Gas separation by composite solvent-swollen membranes  

DOEpatents

There is disclosed a composite immobilized liquid membrane of a solvent-swollen polymer and a microporous organic or inorganic support, the solvent being at least one highly polar solvent containing at least one nitrogen, oxygen, phosphorus or sulfur atom, and having a boiling point of at least 100 C and a specified solubility parameter. The solvent or solvent mixture is homogeneously distributed through the solvent-swollen polymer from 20% to 95% by weight. The membrane is suitable for acid gas scrubbing and oxygen/nitrogen separation. 3 figs.

Matson, S.L.; Lee, E.K.L.; Friesen, D.T.; Kelly, D.J.

1989-04-25

330

New fluorous/organic biphasic systems achieved by solvent tuning  

PubMed Central

Miscibility tests between sixty pairs of fluorous and organic solvents have been performed, and a number of biphasic systems based on hydrofluoroether solvents have been identified. Mutual solubilities of a series of fluorous and organic solvents have been measured to ascertain the compositions of the biphasic systems. A qualitative solvent tuning strategy based on solvent polarity and fluorophilicity/phobicity is introduced. Solvent tuning is then used to modulate the partition coefficients (P) of triarylphosphines with 0–3 fluorous tags. The results lay a foundation for future applications of these and related biphasic systems in catalysis and extraction. PMID:20631912

Chu, Qianli; Yu, Marvin S.; Curran, Dennis P.

2009-01-01

331

Solvent extraction of bitumen from tar sands  

SciTech Connect

This paper reports on the measurement of mass transfer rates for the extraction of bitumen from tar sands using organic solvents. The experiment was carried out in an agitated vessel using a six-blade turbine mixer on a laboratory scale. To facilitate the determination of absolute mass transfer coefficients, tar sands were specially prepared in the form of spherical particles so that mass transfer area can be computed. The variables investigated in the study included: (1) solvent type (kerosene, toluene, benzene), (2) stirrer speed, 25 rpm to 1000 rpm, and (3) particle diameter, 0.4 cm to 1.2 cm. The results indicated that solvency power varied markedly with the various solvents used and that high aromatic content promoted rapid dissolution when compared with paraffinic solvents. The mass transfer rates increased with increasing stirrer speed in accordance with the relationship: k {alpha} N{sup 0.56} where k is the mass transfer coefficient and N the stirrer speed. Increasing particle diameter also resulted in decreased mass transfer rates. The results were satisfactorily correlated in terms of a Frossling type equation, Sh {alpha} Re{sub p}{sup a}Sc{sup b}.

Hoon, A.Y.; Thomas, S. [Univ. of West Indies, St. Augustine (Trinidad and Tobago)

1995-12-31

332

Deep eutectic solvents: syntheses, properties and applications.  

PubMed

Within the framework of green chemistry, solvents occupy a strategic place. To be qualified as a green medium, these solvents have to meet different criteria such as availability, non-toxicity, biodegradability, recyclability, flammability, and low price among others. Up to now, the number of available green solvents are rather limited. Here we wish to discuss a new family of ionic fluids, so-called Deep Eutectic Solvents (DES), that are now rapidly emerging in the current literature. A DES is a fluid generally composed of two or three cheap and safe components that are capable of self-association, often through hydrogen bond interactions, to form a eutectic mixture with a melting point lower than that of each individual component. DESs are generally liquid at temperatures lower than 100 °C. These DESs exhibit similar physico-chemical properties to the traditionally used ionic liquids, while being much cheaper and environmentally friendlier. Owing to these remarkable advantages, DESs are now of growing interest in many fields of research. In this review, we report the major contributions of DESs in catalysis, organic synthesis, dissolution and extraction processes, electrochemistry and material chemistry. All works discussed in this review aim at demonstrating that DESs not only allow the design of eco-efficient processes but also open a straightforward access to new chemicals and materials. PMID:22806597

Zhang, Qinghua; De Oliveira Vigier, Karine; Royer, Sébastien; Jérôme, François

2012-11-01

333

SOLVENT EXTRACTION: SAFETY, HEALTH, AND ENVIRONMENTAL ISSUES  

Technology Transfer Automated Retrieval System (TEKTRAN)

Fats, which are solid at ambient temperature, and liquid oils are recovered from diverse biological sources by mechanical separation, solvent extraction, or a combination of the two methods. There are many physical and chemical differences between these diverse biological materials. However, the s...

334

Crystal growth in fused solvent systems  

NASA Technical Reports Server (NTRS)

Research is reported on the growth of electronic ceramic single crystals from solution for the future growth of crystals in a microgravity environment. Work included growth from fused or glass solvents and aqueous solutions. Topics discussed include: crystal identification and selection; aqueous solution growth of triglycine sulphate (TGS); and characterization of TGS.

Ulrich, D. R.; Noone, M. J.; Spear, K. E.; White, W. B.; Henry, E. C.

1973-01-01

335

Solvents for Soluble Nitrogen Measurements in Feedstuffs  

Microsoft Academic Search

An improved procedure and a new ex- traction apparatus for determining solu- ble nitrogen in feedstuffs are presented. This equipment was used to compare the quantity of nitrogen extracted from seven feedstuffs by several mineral solvents and autoclaved rumen fluid. The quantity of nitrogen extracted by either a modified Burroughs mineral mixture or McDougal's artificial saliva differed from that ex-

B. A. Crooker; C. J. Sniffen; W. H. Hoover; L. L. Johnson

1978-01-01

336

CO-SOLVENT BASED SOURCE REMEDIATION APPROACHES  

EPA Science Inventory

Field pilot scale studies have demonstrated that co-solvent-enhanced in situ extraction can remove residual and free-phase nonaqueous phase liquid (NAPL), but may leave levels of contaminants in the ground water and subsurface formation higher than regulatory requirements for c...

337

REPLACING SOLVENT CLEANING WITH AQUEOUS CLEANING  

EPA Science Inventory

The report documents actions taken by Robert Bosch Corp., Charleston, SC, in replacing the cleaning solvents 1, 1, 2- trichloro-1, 2, 2-trifluoroethane (CFC-113) and trichloroethylene (TCE) with aqueous solutions. osch has succeeded in eliminating all their CFC-113 use and so far...

338

REPLACING SOLVENT CLEANING WITH AQUEOUS CLEANING  

EPA Science Inventory

The report documents actions taken by Robert Bosch Corp., Charleston, SC, in replacing the cleaning solvents 1, 1, 2- trichloro-1, 2, 2-trifluoroethane (CFC-113) and trichloroethylene (TCE) with aqueous solutions. Bosch has succeeded in eliminating all their CFC-113 use and so f...

339

ALTERNATIVE TECHNIQUES FOR MANAGING SOLVENT WASTES  

EPA Science Inventory

There are economic and regulatory incentives for considering alternatives to the direct land disposal of solvent-bearing hazardous waste streams (EPA Hazardous Waste Codes: F001, F002, F003, F004, and F005). These alternatives include recycle/reuse (including use as a fuel substi...

340

Selective solvent absorption in coal conversion  

SciTech Connect

The objectives of this project are: (1) to determine the importance of the presence of added hydrogen donor compounds within the coal in the first stage of direct liquefaction processes; and (2) to determine the composition of the solvent absorbed by and present within the coal in the first stage of direct coal liquefaction.

Larsen, J.W.; Lapucha, A.; Lazarov, L.; Amui, J.

1992-04-01

341

Solvent treatment of coal for improved liquefaction  

DOEpatents

Increased liquefaction yield is obtained by pretreating a slurry of solid carbonaceous material and a liquid hydrocarbonaceous solvent at a temperature above 200.degree. C. but below 350.degree. C. for a period of 10 minutes to four hours prior to exposure to liquefaction temperatures.

Appell, Herbert R. (Pitcairn, PA); Narain, Nand K. (Bethel Park, PA); Utz, Bruce R. (Pittsburgh, PA)

1986-05-06

342

Anomalous solvent extraction behavior of astatine  

Microsoft Academic Search

We studied the solvent extraction behavior of astatine and found the anomalous behavior of this element similar to radioiodine. Astatine was extracted into CS2 from acidic solution over a wide range of carrier iodine concentration. The distribution ratios of astatine were determined by measuring the -ray from 210 At with a Nal(TI) detector. A drastic change was observed around at

N. Takahashi; H. Baba

1997-01-01

343

Coordinated action in multiteam systems.  

PubMed

This study investigated coordinated action in multiteam systems employing 233 correspondent systems, comprising 3 highly specialized 6-person teams, that were engaged in an exercise that was simultaneously "laboratory-like" and "field-like." It enriches multiteam system theory through the combination of theoretical perspectives from the team and the large organization literatures, underscores the differential impact of large size and modular organization by specialization, and demonstrates that conventional wisdom regarding effective coordination in traditional teams and large organizations does not always transfer to multiteam systems. We empirically show that coordination enacted across team boundaries at the component team level can be detrimental to performance and that coordinated actions enacted by component team boundary spanners and system leadership positively impact system performance only when these actions are centered around the component team most critical to addressing the demands of the task environment. PMID:22201246

Davison, Robert B; Hollenbeck, John R; Barnes, Christopher M; Sleesman, Dustin J; Ilgen, Daniel R

2012-07-01

344

Markov Tracking for Agent Coordination  

NASA Technical Reports Server (NTRS)

Partially observable Markov decision processes (POMDPs) axe an attractive representation for representing agent behavior, since they capture uncertainty in both the agent's state and its actions. However, finding an optimal policy for POMDPs in general is computationally difficult. In this paper we present Markov Tracking, a restricted problem of coordinating actions with an agent or process represented as a POMDP Because the actions coordinate with the agent rather than influence its behavior, the optimal solution to this problem can be computed locally and quickly. We also demonstrate the use of the technique on sequential POMDPs, which can be used to model a behavior that follows a linear, acyclic trajectory through a series of states. By imposing a "windowing" restriction that restricts the number of possible alternatives considered at any moment to a fixed size, a coordinating action can be calculated in constant time, making this amenable to coordination with complex agents.

Washington, Richard; Lau, Sonie (Technical Monitor)

1998-01-01

345

Solvent-assisted NMR imaging or heterogeneous coal macromolecular networks  

SciTech Connect

Solvent swelling has been employed to probe the physical structure of coal (1). The swelling behavior of bituminous coals in various solvents has been used to assess different strengths or types of secondary interactions which determine their macromolecular structures (2-5). The phenomenon of solvent transport into coal during solvent swelling has also been extensively investigated by numerous researchers (6-10). Recently, we have obtained important information concerning solvent accessibility in coals and maceral domains by proton NMR imaging of mobile proton distributions resulting from solvent swelling (11). Images of coals swollen with perdeuterated solvents were used to map mobile phases in the coal macromolecular structure, while images obtained with protic solvents mapped distributions of the ingressed solvent. For the present purposes 2-D images are sufficient and their acquisition is suitably fast. In order to ensure that the transport process was also two-dimensional, the upper and lower sample surfaces were protected from solvent infiltration by glass coverslips which restricted the flow of solvent to cross only the exposed faces of the sample. Each sample is rectangular with initial dimensions on the order of 2 {times} 2 {times} 1 mm. The experimental protocol involved immersing the sample in the solvent for a period of time, removing it from the solvent bath, acquiring an image, and re-immersing it. Figure 1 presents transient images together with one-dimensional projections for each of the three macromolecular systems.

French, D.C.; Cody, G.D.; Botto, R.E.

1993-09-01

346

Ionic liquids and deep eutectic solvents in natural products research: mixtures of solids as extraction solvents.  

PubMed

Mixtures of solid chemicals may become liquid under certain conditions. These liquids are characterized by the formation of strong ionic (ionic liquids) or hydrogen bonds (deep eutectic solvents). Due to their extremely low vapor pressure, they are now widely used in polymer chemistry and synthetic organic chemistry, yet little attention has been paid to their use as extraction solvents of natural products. This review summarizes the preparation of ionic liquids and deep eutectic solvents with natural product components and recent progress in their applications to the extraction and analysis of natural products as well as the recovery of extracted compounds from their extracts. Additionally, various factors affecting extraction features of ionic liquids and deep eutectic solvents, as well as potential useful technologies including microwave and ultrasound to increase the extraction efficiency, are discussed. PMID:24188074

Dai, Yuntao; van Spronsen, Jaap; Witkamp, Geert-Jan; Verpoorte, Robert; Choi, Young Hae

2013-11-22

347

AXAF Coordinate Transformation at XRCF  

NASA Technical Reports Server (NTRS)

Coordinate transformation between focal plane and detector pixel systems must be handled carefully at the X-ray Calibration Facility (XRCF) as it will be during flight. The High Resolution Mirror Assembly (HRMA) X-ray Detection System (HXDS) stage dithers, and the five-axis mount (FAM) attachment points underwent various types of motion during testing. At the XRCF when the FAM moved, the Science Instrument Module (SIM) travel direction was not necessarily aligned with the mirror axis motion, and, in addition, an arbitrary position offset had to be calibrated. Misalignment from the mirror axis was assessed by measuring its displacement from the boresight configuration of the default FAM frame, and the HXDS stage was monitored for motion from the default FAM reference point. Mirror position, prescribed in a mirror modal coordinate system, was measured in HRMA pitch and yaw axes. Prior to corrections for dithering and FAM movement, the coordinate data at XRCF also had to be corrected for possible misalignments of the mirror mount relative to XRCF and the default FAM axes due to the movement of the FAM feet. Those misalignments were processed in terms of yaw-pitch-roll Euler angles in the mirror nodal coordinate, and in the default FAM frame, respectively. An AXAF Science Center (ASC) coordinate library, pixlib, has been built to support these coordinate transformations and was used during x-ray calibration at the George C. Marshall Space Flight Center, Huntsville, AL. The design and implementation of this library will be discussed.

He, Helen; McDowell, Jonathan; Conroy, Maureen

1997-01-01

348

Timing and Virtual Observability in Ultimatum Bargaining and "Weak Link" Coordination Games  

E-print Network

of a game, or the way a game is played, can affect behavior in ways that are not predicted by the theory). These results often produce the need to modify theory to take into account missing elements, as Rabin (1993) did of how timing affects behavior. The potential problem with standard game theory comes from the fact

Greer, Julia R.

349

Polysiloxane ionic liquids as good solvents for ?-cyclodextrin-polydimethylsiloxane polyrotaxane structures  

PubMed Central

Summary An ionic liquid based on polydimethylsiloxane with imidazolium salt brushes was synthesized as a good solvent for ?-cyclodextrin-polydimethylsiloxane rotaxane. As expected the PDMS-Im/Br ionic liquid had a liquid-like non-Newtonian behavior with rheological parameters dependent on frequency and temperature. The addition of rotaxane to the ionic liquid strengthened the non-Newtonian character of the sample and a type of stable liquid-like network was formed due to the contribution of weak ionic interactions. The structure is stable in the 20 to 80 °C domain as proved by the oscillatory and rotational rheological tests. PMID:23209493

Marangoci, Narcisa; Ardeleanu, Rodinel; Ursu, Laura; Ibanescu, Constanta; Danu, Maricel; Simionescu, Bogdan C

2012-01-01

350

Partial molar volume fraction of solvent in binary (CO 2–solvent) solution for solid solubility predictions  

Microsoft Academic Search

Prediction of solid solute solubility in an organic solvent with dissolution of dense CO2 as antisolvent is important for the design of antisolvent crystallization processes. A new model is proposed in this work to predict the mole fraction of a pure solid solute in a ternary (CO2–solvent–solid) system at solid–liquid equilibrium. This is based on the hypothesis that CO2 molecules

Mamata Mukhopadhyay; Sameer V. Dalvi

2004-01-01

351

Triplet Thermal Relaxation Study as a Probe of Weak Interdimers of Porphyrin Derivatives  

NASA Astrophysics Data System (ADS)

This article deals with results concerning the study of interacting dyes which are able to create weak interdimers. Two groups of organic systems: phthalocyanines (di-ethanol-amine and di-octane-amine) and pyridyl porphyrins (zinc, copper, and free-base) covalently linked to polyethylene glycol (PEG) in water and organic solvents (dioxane, dimethylsulfoxide) were investigated. Absorption, fluorescence, and photoacoustics were used as experimental methods but particular attention was paid to light-induced optoacoustic spectroscopy to follow the dye's triplet population and triplet thermal relaxation to study intermolecular interactions. It has been shown that even the weak interactions of the organic dyes under study is not detectable by absorption and only slightly by fluorescence is it possible to follow interactions by complementary photothermal methods. The results obtained for selected phthalocyanines and covalent porphyrin-polymer samples evidently show that the light-induced optoacoustic experiment is a perfect tool in the detection of weakly interacting aggregates.

Wróbel, D.; Biadasz, A.; Bursa, B.

2012-04-01

352

Electromagnetic weak turbulence theory revisited  

SciTech Connect

The statistical mechanical reformulation of weak turbulence theory for unmagnetized plasmas including fully electromagnetic effects was carried out by Yoon [Phys. Plasmas 13, 022302 (2006)]. However, the wave kinetic equation for the transverse wave ignores the nonlinear three-wave interaction that involves two transverse waves and a Langmuir wave, the incoherent analogue of the so-called Raman scattering process, which may account for the third and higher-harmonic plasma emissions. The present paper extends the previous formalism by including such a term.

Yoon, P. H. [IPST, University of Maryland, College Park, Maryland 20742 (United States); Ziebell, L. F. [Instituto de Fisica, UFRGS, Porto Alegre, RS (Brazil); Gaelzer, R.; Pavan, J. [Instituto de Fisica e Matematica, UFPel, Pelotas, RS (Brazil)

2012-10-15

353

Motor coordination uses external spatial coordinates independent of developmental vision.  

PubMed

The constraints that guide bimanual movement coordination are informative about the processing principles underlying movement planning in humans. For example, symmetry relative to the body midline benefits finger and hand movements independent of hand posture. This symmetry constraint has been interpreted to indicate that movement coordination is guided by a perceptual code. Although it has been assumed implicitly that the perceptual system at the heart of this constraint is vision, this relationship has not been tested. Here, congenitally blind and sighted participants made symmetrical and non-symmetrical (that is, parallel) bimanual tapping and finger oscillation movements. For both groups, symmetrical movements were executed more correctly than parallel movements, independent of anatomical constraints like finger homology and hand posture. For the blind, the reliance on external spatial factors in movement coordination stands in stark contrast to their use of an anatomical reference frame in perceptual processing. Thus, the externally coded symmetry constraint evident in bimanual coordination can develop in the absence of the visual system, suggesting that the visual system is not critical for the establishment of an external-spatial reference frame in movement coordination. PMID:24727423

Heed, Tobias; Röder, Brigitte

2014-07-01

354

Conforming to coordinate: Children use majority information for peer coordination.  

PubMed

Humans are constantly required to coordinate their behaviour with others. As this often relies on everyone's convergence on the same strategy (e.g., driving on the left side of the road), a common solution is to conform to majority behaviour. In this study, we presented 5-year-old children with a coordination problem: To retrieve some rewards, they had to choose the same of four options as a peer partner - in reality a stooge - whose decision they were unable to see. Before making a choice, they watched a video showing how other children from their partner's peer group had behaved; a majority chose the same option and a minority chose a different one. In a control condition, children watched the same video but could then retrieve the reward irrespective of their partner's choice (i.e., no coordination was necessary). Children followed the majority more often when coordination was required. Moreover, conformers mostly justified their choices by referring to the majority from the video demonstration. This study is the first to show that young children are able to strategically coordinate decisions with peers by conforming to the majority. PMID:25495153

Grueneisen, Sebastian; Wyman, Emily; Tomasello, Michael

2015-03-01

355

Integrating Safety Issues in Optimizing Solvent Selection and Process Design  

E-print Network

Incorporating consideration for safety issues while designing solvent processes has become crucial in light of the chemical process incidents involving solvents that have taken place in recent years. The implementation of inherently safer design...

Patel, Suhani Jitendra

2011-10-21

356

ROSE Process Offers Energy Savings for Solvent Extraction  

E-print Network

Kerr-McGee has developed and commercialized an energy-efficient solvent extraction process known as ROSE (Residuum Oil Supercritical Extraction) in which the extraction solvent is recovered as a supercritical fluid. The energy requirement...

Gearheart, J. A.; Nelson, S. R.

1983-01-01

357

Construction of prototype system for directional solvent extraction desalination  

E-print Network

Directional solvent extraction has been demonstrated as a low temperature, membrane free desalination process. This method dissolves the water into an inexpensive, benign directional solvent, rejects the contaminants, then ...

Fowler, Michael James

2012-01-01

358

40 CFR 52.254 - Organic solvent usage.  

...or herbicides. (4) The employment, application, evaporation, or drying of saturated halogenated hydrocarbons or perchloroethylene...photochemically reactive solvent by any means that will permit the evaporation of such solvent into the atmosphere. (o)...

2014-07-01

359

40 CFR 52.1145 - Regulation on organic solvent use.  

Code of Federal Regulations, 2013 CFR

...photochemically reactive solvent by any means that will permit the evaporation of such solvent into the atmosphere. (g) Emissions of...or herbicides. (3) The employment, application, evaporation, or drying of saturated halogenated hydrocarbons or...

2013-07-01

360

40 CFR 52.1145 - Regulation on organic solvent use.  

...photochemically reactive solvent by any means that will permit the evaporation of such solvent into the atmosphere. (g) Emissions of...or herbicides. (3) The employment, application, evaporation, or drying of saturated halogenated hydrocarbons or...

2014-07-01

361

40 CFR 52.254 - Organic solvent usage.  

Code of Federal Regulations, 2012 CFR

...or herbicides. (4) The employment, application, evaporation, or drying of saturated halogenated hydrocarbons or perchloroethylene...photochemically reactive solvent by any means that will permit the evaporation of such solvent into the atmosphere. (o)...

2012-07-01

362

40 CFR 52.1145 - Regulation on organic solvent use.  

Code of Federal Regulations, 2010 CFR

...photochemically reactive solvent by any means that will permit the evaporation of such solvent into the atmosphere. (g) Emissions of...or herbicides. (3) The employment, application, evaporation, or drying of saturated halogenated hydrocarbons or...

2010-07-01

363

40 CFR 52.254 - Organic solvent usage.  

Code of Federal Regulations, 2010 CFR

...or herbicides. (4) The employment, application, evaporation, or drying of saturated halogenated hydrocarbons or perchloroethylene...photochemically reactive solvent by any means that will permit the evaporation of such solvent into the atmosphere. (o)...

2010-07-01

364

40 CFR 52.1145 - Regulation on organic solvent use.  

Code of Federal Regulations, 2011 CFR

...photochemically reactive solvent by any means that will permit the evaporation of such solvent into the atmosphere. (g) Emissions of...or herbicides. (3) The employment, application, evaporation, or drying of saturated halogenated hydrocarbons or...

2011-07-01

365

40 CFR 52.254 - Organic solvent usage.  

Code of Federal Regulations, 2011 CFR

...or herbicides. (4) The employment, application, evaporation, or drying of saturated halogenated hydrocarbons or perchloroethylene...photochemically reactive solvent by any means that will permit the evaporation of such solvent into the atmosphere. (o)...

2011-07-01

366

BIODEGRADATION OF CHLORINATED SOLVENTS: REACTIONS NEAR DNAPL AND ENZYME FUNCTION  

EPA Science Inventory

Chlorinated solvents are among the most common organic chemical groundwater contaminants at DOE sites, as well as at DOD and industrial facilities. Included are the solvents trichloroethene (TCE), tetrachloroethene (PCE), and carbon tetrachloride (CT). Commonly these contaminan...

367

Propionic acid production by extractive fermentation. 1. Solvent considerations  

Microsoft Academic Search

Solvent selection for extractive fermentation for propionic acid was conducted with three systems: Alamine{reg_sign} 304-1 (trilaurylamine) in 2-octanol, 1-dodecanol, and Witcohol{reg_sign} 85 NF (oleyl alcohol). Among them, the solvent containing 2-octanol exhibited the highest partition coefficient in acid extraction, but it was also toxic to propionibacteria. The most solvent-resistant strain among five strains of the microorganism was selected. Solvent toxicity

Z. Gu; B. A. Glatz; C. E. Glatz

1998-01-01

368

Metal complexes and solvent extraction properties of isonitrosoacetophenone 2-aminobenzoylhydrazone.  

PubMed

Three types of copper complexes as well as an oximate-bridged nickel complex with isonitrosoacetophenone 2-aminobenzoylhydrazone (H(2)L) have been prepared in ethanolic solution and characterized by elemental analyses, IR, (1)H NMR, UV-vis and magnetic susceptibility measurement. IR spectra show the ligand coordinates as a neutral, monoanionic and dianionic O,N,N-tridentate acylhydrazoneoxime ligand depending reaction conditions and metal salts employed. The elemental analyses results, spectroscopic and magnetic data are consistent with the formation of mononuclear copper complexes and binuclear complexes with both copper and nickel. The effects of varying pH and solvent on the absorption behavior of both ligand and complexes have been investigated. The extraction ability of acylhydrazoneoxime ligand has been examined by the liquid-liquid extraction of selected transition metal [Cu(2+), Ni(2+), Co(2+), Cr(3+), Hg(2+), Zn(2+), Cd(2+) and Mn(2+)] cations. The ligand shows strong binding ability toward copper(II) ion. PMID:16495123

Gup, Ramazan; Giziro?lu, Emrah

2006-11-01

369

Low-overhead distributed transaction coordination  

E-print Network

This thesis presents Granola, a transaction coordination infrastructure for building reliable distributed storage applications. Granola provides a strong consistency model, while significantly reducing transaction coordination ...

Cowling, James (James Alexander)

2012-01-01

370

Syntheses, crystal structures, and water adsorption behaviors of jungle-gym-type porous coordination polymers containing nitro moieties  

NASA Astrophysics Data System (ADS)

NO 2 containing dicarboxylate bridging ligands, nitroterephthalate (bdc-NO 2) and 2,5-dinitroterephthalate (bdc-(NO 2) 2), afford porous coordination polymers, {[Zn 2(bdc-NO 2) 2(dabco)]· solvents} n ( 2? solvents) and {[Zn 2(bdc-(NO 2) 2) 2(dabco)]· solvents} n ( 3? solvents). Both compounds form jungle-gym-type regularities, where a 2D square grid composed of dinuclear Zn 2 units and dicarboxylate ligands is bridged by dabco molecules to extend the 2D layers into a 3D structure. In 2? solvents and 3? solvents, a rectangle pore surrounded by eight Zn 2 corners contains two and four NO 2 moieties, respectively. Thermal gravimetry (TG) and X-ray powder diffraction (XRPD) measurements reveal that both compounds maintain the frameworks regularities without guest molecules and with solvents such as MeOH, EtOH, i-PrOH, and Me 2CO. Adsorption measurements reveal that dried 2 and 3 adsorb H 2O molecules to be {[Zn 2(bdc-NO 2) 2(dabco)]·4H 2O} n ( 2?4H 2O) and {[Zn 2(bdc-(NO 2) 2) 2(dabco)]·6H 2O} n ( 3?6H 2O), showing the pore hydrophilicity enhancement caused by NO 2 group introduction.

Uemura, Kazuhiro; Onishi, Fumiaki; Yamasaki, Yukari; Kita, Hidetoshi

2009-10-01

371

Caustics of weak shock waves  

NASA Astrophysics Data System (ADS)

The caustics of weak shock waves are studied through matched asymptotic expansions. It is shown that these caustics are thinner and more intense than those of smooth waves with a comparable amplitude. This difference in scalings solves a paradox that would have the caustics of weak shock waves behave linearly, even though linear theory for discontinuous fronts predicts infinite amplitudes near the caustic and in the reflected wave. With the new scalings, the behavior of shocks both near the caustic and in the far field is described by nonlinear equations. The new scales are robust, in the sense that they survive the addition of a small amount of viscosity to the equations. As a viscous shock approaches the caustic, its intensity amplifies and its width decreases in such a way that the new scalings are actually reinforced. A new paradox arises, however: The nonlinear Tricomi equation which describes the behavior of the fronts near caustics does not appear to admit the triple shock intersections which have been observed experimentally. This new open problem is closely related to the von Neumann paradox of oblique shock reflection.

Rosales, Rodolfo R.; Tabak, Esteban G.

1998-01-01

372

Toroidal condensates of semiflexible polymers in poor solvents: adsorption, stretching, and compression.  

PubMed Central

When a semiflexible polymer chain is placed in a poor solvent, or in the presence of condensing agents, a toroidal condensate can result. In typical experiments, these condensates are adsorbed to surfaces. Here we examine the changes that can occur when a toroid is adsorbed. We then examine the behavior of a toroid when stretched and identify two regimes: a weak stretching regime where the toroid deforms from a circle to an ellipse, and a strong stretching regime where a tether is pulled from the toroid. In the weak stretching regime, the force increases linearly with separation whereas in the strong stretching regime, the applied force is a constant. We then look at the case of a toroid compressed in the plane of the toroid. In this case the form of the force law depends on how strongly the toroid wets the surfaces. In general, an inverse square force law is found. PMID:11159392

Pereira, G G; Williams, D R

2001-01-01

373

On Weakly von Neumann regular rings  

Microsoft Academic Search

In this paper, we define and study a particular case of von Neumann regular notion called a weak von Neumann regular ring. It shown that the polynomial ring $R[x]$ is weak von Neumann regular if and only if $R$ has exactly two idempotent elements. We provide necessary and sufficient conditions for $ R=A\\\\propto E $ to be a weak von

Mohammed Kabbour; Najib Mahdou

2009-01-01

374

Weak theories of truth and explicit mathematics  

E-print Network

Weak theories of truth and explicit mathematics Sebastian Eberhard Thomas Strahm Version of August, 2011 Abstract We study weak theories of truth over combinatory logic and their relationship to weak systems of explicit mathematics. In particular, we consider two truth theories TPR and TPT of primitive

Jäger, Gerhard

375

Extractors with Weak Random Seeds Weizmann Institute  

E-print Network

to extract randomness from a weak random source. For every such extractor E, with seed of length d, weExtractors with Weak Random Seeds Ran Raz # Weizmann Institute ran.raz@weizmann.ac.il Abstract We show how to extract random bits from two or more independent weak random sources in cases where only

Raz, Ran

376

Mechanisms of coordination in distributed neural circuits: encoding coordinating information.  

PubMed

We describe synaptic connections through which information essential for encoding efference copies reaches two coordinating neurons in each of the microcircuits that controls limbs on abdominal segments of the crayfish, Pacifastacus leniusculus. In each microcircuit, these coordinating neurons fire bursts of spikes simultaneously with motor neurons. These bursts encode timing, duration, and strength of each motor burst. Using paired microelectrode recordings, we demonstrate that one class of nonspiking neurons in each microcircuit's pattern-generating kernel--IPS--directly inhibits the ASCE coordinating neuron that copies each burst in power-stroke (PS) motor neurons. This inhibitory synapse parallels IPS's inhibition of the same PS motor neurons. Using a disynaptic pathway to control its membrane potential, we demonstrate that a second type of nonspiking interneuron in the pattern-generating kernel--IRSh--inhibits the DSC coordinating neuron that copies each burst in return-stroke (RS) motor neurons. This inhibitory synapse parallels IRS's inhibition of the microcircuit's RS motor neurons. Experimental changes in the membrane potential of one IPS or one IRSh neuron simultaneously changed the strengths of motor bursts, durations, numbers of spikes, and spike frequency in the simultaneous ASCE and DSC bursts. ASCE and DSC coordinating neurons link the segmentally distributed microcircuits into a coordinated system that oscillates with the same period and with stable phase differences. The inhibitory synapses from different pattern-generating neurons that parallel their inhibition of different sets of motor neurons enable ASCE and DSC to encode details of each oscillation that are necessary for stable, adaptive synchronization of the system. PMID:24741053

Smarandache-Wellmann, Carmen; Grätsch, Swantje

2014-04-16

377

Effect of Solvents on the Absorption Spectrum of Vitamin A  

Microsoft Academic Search

IT has long been known that some substances, for example, indigo, yield variously coloured solutions in different solvents. Change of solvent may affect the intensity and position of absorption maxima in the ultra-violet as well as in the visible spectrum. The fact that this phenomenon has been observed with a related substance, carotene, makes it the stranger that various solvents

E. Lester Smith; Babette E. Stern; F. E. Young

1938-01-01

378

Catalytic coal liquefaction with treated solvent and SRC recycle  

DOEpatents

A process for the solvent refining of coal to distillable, pentane soluble products using a dephenolated and denitrogenated recycle solvent and a recycled, pentane-insoluble, solvent-refined coal material, which process provides enhanced oil-make in the conversion of coal.

Garg, Diwakar (Macungie, PA); Givens, Edwin N. (Bethlehem, PA); Schweighardt, Frank K. (Allentown, PA)

1986-01-01

379

Prediction of deep eutectic solvents densities at different temperatures  

Microsoft Academic Search

Predicting densities of nonconventional solvents like deep eutectic solvents (DESs) as a function of temperature is of considerable importance in the development and design of new processes utilizing these solvents. Because of the nature of bonding existing between the salt and the hydrogen bond donor, conventional methods result in very large deviations. In this study, the density of DESs based

K. Shahbaz; F. S. Mjalli; M. A. Hashim; I. M. Alnashef

2011-01-01

380

CHLORINATED SOLVENTS TRANSPORT AND NATURAL ATTENUATION MODELING IN GROUNDWATER  

E-print Network

CHLORINATED SOLVENTS TRANSPORT AND NATURAL ATTENUATION MODELING IN GROUNDWATER F. QUIOT1 , C.Goblet@ensmp.fr Keywords : numerical model, groundwater contamination, chlorinated solvents, natural atténuation atténuation models to predict transport and fate of chlorinated solvents in saturated groundwater Systems

Boyer, Edmond

381

Density-Based Correlation for Solid Solubility in Supercritical Solvents  

Microsoft Academic Search

The use of solvents at conditions above their critical points is increasing because of their increased dissolving power and enhanced transport properties, as in caffeine extraction, etc. This research sought an improved method for correlating the solubility of materials in light solvents from conditions below the critical point of the solvents to those above it, especially to facilitate prediction, interpolation,

Churlhee Lee; Rex T. Ellington

1987-01-01

382

Biocatalysis of chlorophyllase from Phaeodactylum tricornutum in organic solvent media  

Microsoft Academic Search

The biocatalysis of partially purified chlorophyllase from Phaeodactylum tricornutum in an organic solvent medium was investigated. The optimum amounts of water and organic solvent required for the chlorophyllase-catalyzed hydrolytic activity were measured in a wide range of solvents, including acetone, ethanol, propanol, butanol, pentanol, hexanol, toluene, pentane, hexane, octane, and heptane as a function of their hydrophobicities. The logarithm of

Ali Khamessan; Selim Kermasha; Pierre Marsot

1995-01-01

383

Solvation properties of ubiquinone-10 in solvents of different polarity  

Microsoft Academic Search

The solvation properties of ubiquinone-10 and ubiquinol-10 in a wide variety of solvents of polarity varying from alkanes to water are reported. Greatest solubility is observed in solvents of intermediate polarity and particularly where low polarity is combined with a pronounced tendency to interact with the benzoquinone substituent of the ubiquinone molecule. This includes solvents like chloroform and benzene. Ubiquinone-10

Monica Ondarroa; Santosh K. Sharma; Peter J. Quinn

1986-01-01

384

Dissolution of cellulose in anhydrous chloral\\/aprotic solvents  

Microsoft Academic Search

Two new approaches toward the chemical modification and rapid dissolution of cellulose pulp in aprotic solvents containing chloral are presented. In the first method, cellulose pulp is water activated and then solvent exchanged prior to the addition of chloral. In the second method, cellulose pulp is heated in refluxing solvent and then cooled to ambient temperature before the addition of

Adel El-Kafrawy; Albin F. Turbak

1982-01-01

385

ALTERNATIVES TO CHLORINATED SOLVENTS FOR CLEANING AND DEGREASING  

EPA Science Inventory

This guide describes chemical alternatives to chlorinated solvents that eliminate the use of ozone-depleting chlorinated solvents and smog-forming solvents that contribute high levels of volatile organic compounds (VOC) to the atmosphere. oth commercially available and emerging c...

386

MODELING OF CHLORINATED SOLVENTS TRANSPORT AND NATURAL ATTENUATION IN GROUNDWATER  

E-print Network

MODELING OF CHLORINATED SOLVENTS TRANSPORT AND NATURAL ATTENUATION IN GROUNDWATER Thème B, Groundwater contamination, Chlorinated solvents, Natural Atténuation, Biodégradation, Sorption thé fate and transport of chlorinated solvents and their dégradation products in saturated groundwater

Paris-Sud XI, Université de

387

Distribution behavior of astatine: Solvent extraction and back extraction  

Microsoft Academic Search

The distribution behavior of astatine was studied at tracer concentrations and over a wide range of carrier iodide concentration in both solvent extraction and back extraction processes. Astatine compounds were extracted instantly into the organic solvent, CS2 from the carrier free and carrier iodide containing solutions. Back extraction of astatine with various NaOH solutions followed by solvent extraction caused the

M. S. Sultana; A. Toyoshima; N. Takahashi; H. Baba

2001-01-01

388

Evaluation of solvent selectivity in dewaxing and deoiling  

Microsoft Academic Search

Previous literature on the efficiency of solvents used in removing paraffin wax by decrystallization is insufficient. A method for evaluating selectivity and mixtures of solvents is offered. General solvents MEK, acetone, MIBK are tested in various raw materials, then graphed. It is found that the ratio of the slope of the curve for the temperature of equal solubility (TES) as

N. V. Alperovich; A. N. Leonidov; S. P. Sokolova

1983-01-01

389

Dynamic structural transformations of coordination supramolecular systems upon exogenous stimulation.  

PubMed

Reactions in the solid state, especially single-crystal-to-single-crystal (SC-SC) transformations, provide an appealing pathway to obtain target crystalline materials with modified properties via a solvent-free green chemistry approach. This feature article focuses on the progress to date in the context of coordination supramolecular systems (CSSs), especially coordination polymers (CPs) or metal-organic frameworks (MOFs), which show interesting dynamic natures upon exposure to various exogenous stimuli, including concentration, temperature, light and mechanical force, as well as their synergic effect. In essence, dynamic CSSs normally possess crucial crystalline-reactive characteristics: (i) metal ions or clusters with unstable or metastable electronic configurations and coordination geometries; (ii) organic ligands bearing physicochemically active functional groups for subsequent reactions; (iii) polymeric networks of high flexibility for structural bending, rotation, swelling, or shrinking; (iv) guest moieties to be freely exchanged or eliminated by varying the environmental conditions. The significant changes in catalytic, sorption, magnetic, or luminescent properties accompanied by the structural transformations will also be discussed, which reveal the proof-of-concept thereof in designing new functional crystalline materials. PMID:25501443

Li, Cheng-Peng; Chen, Jing; Liu, Chun-Sen; Du, Miao

2015-02-01

390

Interfacial Bond-Breaking Electron Transfer in Mixed Water–Ethylene Glycol Solutions: Reorganization Energy and Interplay between Different Solvent Modes  

PubMed Central

We explore solvent dynamics effects in interfacial bond breaking electron transfer in terms of a multimode approach and make an attempt to interpret challenging recent experimental results (the nonmonotonous behavior of the rate constant of electroreduction of S2O82– from mixed water–EG solutions when increasing the EG fraction; see Zagrebin, P.A. et al. J. Phys. Chem. B2010, 114, 311). The exact expansion of the solvent correlation function (calculated using experimental dielectric spectra) in a series predicts the splitting of solvent coordinate in three independent modes characterized by different relaxation times. This makes it possible to construct a 5D free-energy surface along three solvent coordinates and one intramolecular degree of freedom describing first electron transfer at the reduction of a peroxodisulphate anion. Classical molecular dynamics simulations were performed to study the solvation of a peroxodisulphate anion (S2O82–) in oxidized and reduced states in pure water and ethylene glycol (EG) as well as mixed H2O–EG solutions. The solvent reorganization energy of the first electron-transfer step at the reduction of S2O82– was calculated for several compositions of the mixed solution. This quantity was found to be significantly asymmetric. (The reorganization energies of reduction and oxidation differ from each other.) The averaged reorganization energy slightly increases with increasing the EG content in solution. This finding clearly indicates that for the reaction under study the static solvent effect no longer competes with solvent dynamics. Brownian dynamics simulations were performed to calculate the electron-transfer rate constants as a function of the solvent composition. The results of the simulations explain the experimental data, at least qualitatively. PMID:23768162

2013-01-01

391

Syntheses and structural studies of coordination polymers with microporous frameworks  

NASA Astrophysics Data System (ADS)

The purpose of this work is to synthesize microporous solids using coordination chemistry. The syntheses were carried by diffusion method. Starting reagents, solvent, concentration, reaction speed and time, and temperature were the variables used to optimize the syntheses. The resulting products were characterized by single crystal X-ray diffraction to determine their structures. X-ray powder diffraction, TGA, IR, elemental analysis, and electron microprobe were used to provide complementary or supporting information. Exploratory studies were carried out mainly on organotin-cyanometalate compounds [(RmSnIV)x{M(CN)n} y]. The compounds are made up of SnRm cations and M(CN) n anions. The structures adopted are determined by the number and size of the organic ligands attached to the Sn atoms and by the cyanometalate M(CN) n moiety. Several new compounds in this class were synthesized and structurally characterized. They are [(Bu3Sn)3M(CN)6] (M = Fe, Co), [(R2Sn)3{CO(CN)6}2·X] (R = vinyl, butyl, and propyl), and [(Ph3Sn)2Ni(CN) 4 Ph3SnOH·˜0.8CH3CN·˜0.2H 2O]. The compound [(Ph3Sn)2Ni(CN)4·Ph 3SnOH·˜0.8CH3CN·˜0.2H2O] is to our knowledge, the first three dimensional cyanometalate coordination polymer with expanded inorganic NbO structure. The framework is not interpenetrated and the large central cavity in the structure is filled by inclusion of Ph 3SnOH and other solvent molecules during synthesis. In addition to the investigation of organotin-cyanometalate compounds, other approaches to microporous solids were also studied. A new compound [Co(H 2O)2Ni(CN)4·4H2O] in the Hofmann's clathrate family was obtained. Five one dimensional polymers synthesized by the reaction of dirhodium(II) tetraacetate with 1,4-dicyanobenzene in different solvent systems were also synthesized, and the effect of solvent on the resulting structures was investigated.

Niu, Tianyan

392

Development of a solvent processed insensitive propellant  

NASA Technical Reports Server (NTRS)

Two types of low vulnerability propellants are studied which are distinguished by whether the binder is a rubber, such as polyurethane or CTBN, or a plasticizable polymer such as ethyl cellulose or cellulose acetate. The former propellants are made by a partial cure extrusion process while the latter are made by the conventional solvent process. Emphasis is given to a cellulose binder (plasticizer) RDX composition. The type of binder used, the particle size of the RDX and the presence of small quantities of nitrocellulose in the solvent processed compositions have important influences on the mechanical and combustion characteristics of the propellant. The low temperature combustion is of particular concern because of potential breakup of the grains that can lead to instability.

Trask, R.; Costa, E.; Beardell, A. J.

1980-01-01

393

Gamma Ray Radiolysis of the FPEX Solvent  

SciTech Connect

Slide presentation. FPEX contains a calixarene for Cs extraction, a crown ether for Sr extraction, Cs7SB modifier, and TOA to aid in stripping, in Isopar L diluent. The radiation stability FPEX must be evaluated prior to process use. Radiolytic degradation of species in solution are due to reaction with the direct radiolysis products of the diluent. In Isopar L, the reactive species produced include e-, •H and alkane radicals, resulting in a reducing environment. However, in nitric acid, oxidizing hydroxyl (•OH) and nitro (•NO2) radicals dominate system chemistry. Thus, the nature of diluent and the presence of radical scavengers affect the results of irradiation. We report the preliminary results of a new program to investigate the radiolysis of FPEX using the 60Co irradiation of FPEX neat solvent, acid pre-equilibrated solvent and mixed aerated phases. The Cs and Sr distribution ratios were used as metrics.

B. J. Mincher; S. P. Mezyk; D. R. Peterman

2006-09-01

394

Selective solvent absorption in coal conversion  

SciTech Connect

The objectives of this research are: (1) to determine the importance of the presence of added hydrogen donor compounds within the coal in the first stage of direct liquefaction processes; and (2) to determine the composition of the solvent absorbed by and present within the coal in the first stages of direct coal liquefaction. Scope of work study the conversion of Argonne Premium coals in tetralin and 2-t-butyltetralin and compare the following: conversion to soluble products and product composition. Hydrogen donated by both solvents will be measured by gas chromatography and the same technique will be used to establish the amount of dealkylation of 2-t-butyltetralin. Reactions will be performed at several different temperatures for varying amounts of time.

Larsen, J.W.; Amui, J.

1992-06-01

395

Production of biodiesel using expanded gas solvents  

SciTech Connect

A method of producing an alkyl ester. The method comprises providing an alcohol and a triglyceride or fatty acid. An expanding gas is dissolved into the alcohol to form a gas expanded solvent. The alcohol is reacted with the triglyceride or fatty acid in a single phase to produce the alkyl ester. The expanding gas may be a nonpolar expanding gas, such as carbon dioxide, methane, ethane, propane, butane, pentane, ethylene, propylene, butylene, pentene, isomers thereof, and mixtures thereof, which is dissolved into the alcohol. The gas expanded solvent may be maintained at a temperature below, at, or above a critical temperature of the expanding gas and at a pressure below, at, or above a critical pressure of the expanding gas.

Ginosar, Daniel M [Idaho Falls, ID; Fox, Robert V [Idaho Falls, ID; Petkovic, Lucia M [Idaho Falls, ID

2009-04-07

396

Deep eutectic solvents: sustainable media for nanoscale and functional materials.  

PubMed

Deep eutectic solvents (DESs) represent an alternative class of ionic fluids closely resembling room-temperature ionic liquids (RTILs), although, strictly speaking, they are distinguished by the fact that they also contain an organic molecular component (typically, a hydrogen bond donor like a urea, amide, acid, or polyol), frequently as the predominant constituent. Practically speaking, DESs are attractive alternatives to RTILs, sharing most of their remarkable qualities (e.g., tolerance to humidity, negligible vapor pressure, thermostability, wide electrochemical potential windows, tunability) while overcoming several limitations associated with their RTIL cousins. Particularly, DESs are typically, less expensive, more synthetically accessible (typically, from bulk commodity chemicals using solvent/waste-free processes), nontoxic, and biodegradable. In this Account, we provide an overview of DESs as designer solvents to create well-defined nanomaterials including shape-controlled nanoparticles, electrodeposited films, metal-organic frameworks, colloidal assemblies, hierarchically porous carbons, and DNA/RNA architectures. These breakthroughs illustrate how DESs can fulfill multiple roles in directing chemistry at the nanoscale: acting as supramolecular template, metal/carbon source, sacrificial agent (e.g., ammonia release from urea), and/or redox agent, all in the absence of formal stabilizing ligand (here, solvent and stabilizer are one and the same). The ability to tailor the physicochemical properties of DESs is central to controlling their interfacial behavior. The preorganized "supramolecular" nature of DESs provides a soft template to guide the formation of bimodal porous carbon networks or the evolution of electrodeposits. A number of essential parameters (viscosity, polarity, surface tension, hydrogen bonding), plus coordination with solutes/surfaces, all play significant roles in modulating species reactivity and mass transport properties governing the genesis of nanostructure. Furthermore, DES components may modulate nucleation and growth mechanisms by charge neutralization, modification of reduction potentials (or chemical activities), and passivation of particular crystal faces, dictating growth along preferred crystallographic directions. Broad operational windows for electrochemical reactions coupled with their inherent ionic nature facilitate the electrodeposition of alloys and semiconductors inaccessible to classical means and the use of cosolvents or applied potential control provide under-explored strategies for mediating interfacial interactions leading to control over film characteristics. The biocompatibility of DESs suggests intriguing potential for the construction of biomolecular architectures in these novel media. It has been demonstrated that nucleic acid structures can be manipulated in the ionic, crowded, dehydrating (low water activity) DES environment-including the adoption of duplex helical structures divergent from the canonical B form and parallel G-quadruplex DNA persisting near water's boiling point-challenging the misconception that water is a necessity for maintenance of nucleic acid structure/functionality and suggesting an enticing trajectory toward DNA/RNA-based nanocatalysis within a strictly anhydrous medium. DESs offer tremendous opportunities and open intriguing perspectives for generating sophisticated nanostructures within an anhydrous or low-water medium. We conclude this Account by offering our thoughts on the evolution of the field, pointing to areas of clear and compelling utility which will surely see fruition in the coming years. Finally, we highlight a few hurdles (e.g., need for a universal nomenclature, absence of water-immiscible, oriented-phase, and low-viscosity DESs) which, once navigated, will hasten progress in this area. PMID:24892971

Wagle, Durgesh V; Zhao, Hua; Baker, Gary A

2014-08-19

397

Generalized spherical and simplicial coordinates  

NASA Astrophysics Data System (ADS)

Elementary trigonometric quantities are defined in l2,p analogously to that in l2,2, the sine and cosine functions are generalized for each p>0 as functions sinp and cosp such that they satisfy the basic equation cosp([phi])p+sinp([phi])p=1. The p-generalized radius coordinate of a point [xi][set membership, variant]Rn is defined for each p>0 as . On combining these quantities, ln,p-spherical coordinates are defined. It is shown that these coordinates are nearly related to ln,p-simplicial coordinates. The Jacobians of these generalized coordinate transformations are derived. Applications and interpretations from analysis deal especially with the definition of a generalized surface content on ln,p-spheres which is nearly related to a modified co-area formula and an extension of Cavalieri's and Torricelli's indivisibeln method, and with differential equations. Applications from probability theory deal especially with a geometric interpretation of the uniform probability distribution on the ln,p-sphere and with the derivation of certain generalized statistical distributions.

Richter, Wolf-Dieter

2007-12-01

398

Enzyme-Catalyzed Processes in Organic Solvents  

Microsoft Academic Search

Three different lipases (porcine pancreatic, yeast, and mold) can vigorously act as catalysts in a number of nearly anhydrous organic solvents. Various transesterification reactions catalyzed by porcine pancreatic lipase in hexane obey Michaelis-Menten kinetics. The dependence of the catalytic activity of the enzyme in organic media on the pH of the aqueous solution from which it was recovered is bell-shaped,

Aleksey Zaks; Alexander M. Klibanov

1985-01-01

399

Animation of Gas Chromatography Solvent Focusing  

NSDL National Science Digital Library

This site has very good animations related to separations. It deals specifically with solvent focusing in gas chromatography. The animations are short (one to two minutes) and can easily be shown in class as part of a lecture. They are extremely helpful in illustrating key components and concepts of chromatographic systems. Users are encouraged to explore the site and the other brief animations as well. Separate links to other simulations by the same company (TRSL) are also listed on ASDL.

400

Improvements in solvent-signal suppression  

NASA Astrophysics Data System (ADS)

Three recent improvements in solvent-signal suppression are described. First, PJR ("power-adapted jump and return") replaces JR (jump and return). It goes beyond the "infinitely short {?}/{2} pulse" approximation and can therefore be used even when the available RF power is low. The phase shift is small, and the amplitude correction providing a flat response is simple and power-independent. With a postexcitation delay, PJR generates an echo. Second, "modified binomials," i.e., binomials sandwiched between two ? pulses are studied. This simple modification eliminates the linear phase shift, which is the main problem of binomial sequences. It has a clear theoretical basis. These two sequences are applied to the observation of a test sample of thymidine, following a proposed standard procedure for the evaluation of methods of solvent-signal suppression. Third, it is pointed out that the elimination of radiation damping would avoid the resulting rotation of the magnetic moment during the RF-free intervals within solvent-signal-suppression excitation sequences. It may be achieved by incorporating the coil in an open, series-tuned, matching circuit.

Guéron, Maurice; Plateau, Pierre; Kettani, Ali; Decorps, Michel

401

Aliphatic hydrocarbon solvents in chemically sensitive patients.  

PubMed

The purpose of the present study was to see if chemically sensitive individuals had aliphatic hydrocarbon solvents as part of their total body load. This was done by measuring blood levels from 85 chemically sensitive patients. These were measured by a purging trap method with gas chromatography/mass spectrometry (GCC/MS) by the methods of Laseter. Thirteen patients had blood levels below the detection limit of less than 1 ppb and 72 were above the detection limit. An average of three solvents, out of seven measured, including n-pentane, 2,2-dimethylbutane, cyclopentane, 2-methylpentane, 3-methylpentane, n-hexane, n-heptane, was found in 85% of the patients' blood on the 1 to 299 ppb range. The means were as follows: n-pentane 14.7 ppb, 2,2-dimethylbutane 2.5 ppb, cyclopentane 9.0 ppb, 2-methylpentane 16.7 ppb, 3-methylpentane 28.0 ppb, n-heptane 5.5 ppb. The most frequently found of the above solvents was 2-methylpentane (found in 68.1% of the patients), 3-methylpentane (62.5%), n-hexane (61.1%), and pentane (40.3%). PMID:1817510

Pan, Y; Johnson, A R; Rea, W J

1991-07-01

402

The Coordinated Regional Downscaling Experiment (CORDEX) (Invited)  

NASA Astrophysics Data System (ADS)

The Coordinated Regional Downscaling Experiment (CORDEX) is a program developed by the Task Force on Regional Climate Downscaling of World Climate Research Programme (WCRP). The Task Force’s mandate is to develop a framework to evaluate regional climate downscaling techniques; foster an international coordinated effort to develop improved downscaling techniques and to provide feedback to the global modelling community; and promote greater interactions between global climate modelers, downscalers and end-users. Within this mandate, the primary goal of CORDEX is to extend to a global framework the lessons learned from regional climate downscaling programs focused on one continent. The framework includes regional climate models (RCMs) and statistical downscaling, with an aim of evaluating the strengths and weaknesses of downscaled climate information. CORDEX also provides coordination among existing and emerging downscaling programs around the world. CORDEX has defined a set of target domains covering most land areas of the planet, as well as a set of simulation protocols. A primary region of emphasis is Africa, which has received less attention than most other continents in regional climate-change and climate-impacts research. Baseline RCM simulations have started, using the ERA-Interim reanalysis for boundary conditions that will cover 1987-2007. RCMs driven bv global climate models (GCMs) will simulate the period 1950-2100, where the RCMs and driving GCMs will use Representative Concentration Pathway (RCP) greenhouse gas and aerosol scenarios for the future portion, specifically RCP 4.5 and RCP 8.5. Interested groups with limited computing resources will focus on selected 30-year periods of present and future scenario climates. CORDEX has established a preliminary set of archival protocols and targeted variables for output that will be stored in a central, openly accessible repository. Although CORDEX intends to produce simulations and analyses for the IPCC Fifth Assessment Report, the WCRP Task Force views CORDEX as an ongoing program that will extend beyond the IPCC AR5. This talk will outline ways in which interested groups can participate through simulation and analyses.

Gutowski, W. J.

2009-12-01

403

Expanding GSK’s Solvent Selection Guide—application of life cycle assessment to enhance solvent selections  

Microsoft Academic Search

Solvents play an important role in the pharmaceutical, chemical and allied industries, with millions of tons used and disposed of each year. GlaxoSmithKline (GSK) previously reported on the development of a Solvent Selection Guide (SSG) that provides scientists with concise environment, health and safety (EHS) data and guidance for solvents. The Guide facilitates the inclusion of EHS considerations in early

Concepción Jiménez-González; Alan D. Curzons; David J. C. Constable; Virginia L. Cunningham

2004-01-01

404

Measuring Motor Coordination in Mice  

PubMed Central

Mice are increasingly being used in behavioral neuroscience, largely replacing rats as the behaviorist's animal of choice. Before aspects of behavior such as emotionality or cognition can be assessed, however, it is vital to determine whether the motor capabilities of e.g. a mutant or lesioned mouse allow such an assessment. Performance on a maze task requiring strength and coordination, such as the Morris water maze, might well be impaired in a mouse by motor, rather than cognitive, impairments, so it is essential to selectively dissect the latter from the former. For example, sensorimotor impairments caused by NMDA antagonists have been shown to impair water maze performance2. Motor coordination has traditionally been assessed in mice and rats by the rotarod test, in which the animal is placed on a horizontal rod that rotates about its long axis; the animal must walk forwards to remain upright and not fall off. Both set speed and accelerating versions of the rotarod are available. The other three tests described in this article (horizontal bar, static rods and parallel bars) all measure coordination on static apparatus. The horizontal bar also requires strength for adequate performance, particularly of the forelimbs as the mouse initially grips the bar just with the front paws. Adult rats do not perform well on tests such as the static rods and parallel bars (personal observations); they appear less well coordinated than mice. I have only tested male rats, however, and male mice seem generally less well coordinated than females. Mice appear to have a higher strength:weight ratio than rats; the Latin name, Mus musculus, seems entirely appropriate. The rotarod, the variations of the foot fault test12 or the Catwalk (Noldus)15 apparatus are generally used to assess motor coordination in rats. PMID:23748408

Deacon, Robert M.J.

2013-01-01

405

Coordinative variability and overuse injury  

PubMed Central

Overuse injuries are generally defined as a repetitive micro-trauma to tissue. Many researchers have associated particular biomechanical parameters as an indicator of such injuries. However, while these parameters have been reported in single studies, in many instances, it has been difficult to verify these parameters as causative to the injury. We have investigated overuse injuries, such as patella-femoral pain syndrome, using a dynamical systems approach. Using such methods, the importance of the structure of coordinative variability (i.e. the variability of the interaction between segments or joints) becomes apparent. We view coordinative variability as functionally important to the movement and different from end-point or goal variability. Using concepts derived from the work of Bernstein, we conducted studies using a continuous relative phase and/or modified vector coding approaches to investigate the coordinative variability of overuse injuries. Consistently, we have found that the higher variability state of a coordinative structure is the healthy state while the lower variability state is the unhealthy or pathological state. It is clear that very high coordinative variability could also result in injury and that there must be a window of ‘higher variability’ in which non-injured athletes function. While this finding that coordinative variability is functional has been shown in several studies, it is still not clear if reduced variability contributes to or results from the injury. Studies are currently underway to determine the potential reasons for the reduced variability in injured athletes. Nevertheless, our laboratory believes that this understanding of how joints interact can be important in understanding overuse injuries. PMID:23186012

2012-01-01

406

An Application View of COORDINATORS Coordination Managers for First Responders  

E-print Network

or endorsements, either expressed or implied, of the Defense Advanced Research Projects Agency (DARPA), the Air Advanced Research Projects Agency (DARPA) and the Air Force Research Laboratory (AFRL) under agreement the situation changes, the COORDINATORs communicate, evaluate the implications ¡ Effort sponsored by the Defense

Wagner, Thomas

407

Weak measurement of cotunneling time  

NASA Astrophysics Data System (ADS)

Quantum mechanics allows the existence of "virtual states" that have no classical analog. Such virtual states defy direct observation through strong measurement, which would destroy the volatile virtual state. Here, we show how a virtual state of an interacting many-body system can be detected employing a weak measurement protocol with post-selection. We employ this protocol for the measurement of the time it takes an electron to tunnel through a virtual state of a quantum dot (cotunneling). Contrary to classical intuition, this cotunneling time is independent of the strength of the dot-lead coupling and may deviate from that predicted by time-energy uncertainty relation. Our approach, amenable to experimental verification, may elucidate an important facet of quantum mechanics which hitherto was not accessible by direct measurements.

Romito, Alessandro; Gefen, Yuval

2014-08-01

408

Weak measurement of cotunneling time  

E-print Network

Quantum mechanics allows the existence of "virtual states" that have no classical analogue. Such virtual states defy direct observation through strong measurement, which would destroy the volatile virtual state. Here we show how a virtual state of an interacting many-body system can be detected employing a weak measurement protocol with postselection. We employ this protocol for the measurement of the time it takes an electron to tunnel through a virtual state of a quantum dot (cotunneling). Contrary to classical intuition, this cotunneling time is independent of the strength of the dot-lead coupling and may deviate from that predicted by time-energy uncertainty relation. Our approach, amenable to experimental verification, may elucidate an important facet of quantum mechanics which hitherto was not accessible by direct measurements.

Alessandro Romito; Yuval Gefen

2014-10-24

409

Weak lensing cosmology beyond ?CDM  

SciTech Connect

Weak gravitational lensing is one of the key probes of the cosmological model, dark energy, and dark matter, providing insight into both the cosmic expansion history and large scale structure growth history. Taking into account a broad spectrum of physics affecting growth — dynamical dark energy, extended gravity, neutrino masses, and spatial curvature — we analyze the cosmological constraints. Similarly we consider the effects of a range of systematic uncertainties, in shear measurement, photometric redshifts, intrinsic alignments, and the nonlinear power spectrum, on cosmological parameter extraction. We also investigate, and provide fitting formulas for, the influence of survey parameters such as redshift depth, galaxy number densities, and sky area on the cosmological constraints in the beyond-?CDM parameter space. Finally, we examine the robustness of results for different fiducial cosmologies.

Das, Sudeep; Linder, Eric V.; Nakajima, Reiko [Berkeley Center for Cosmological Physics, University of California, Berkeley, CA (United States); Putter, Roland de, E-mail: sdas@hep.anl.gov, E-mail: rdeputter@icc.ub.edu, E-mail: evlinder@lbl.gov, E-mail: reiko@astro.uni-bonn.de [IFIC, Universidad de Valencia-CSIC, Valencia (Spain)

2012-11-01

410

The Development of a Microscale Continuous Hot Solvent Extractor  

NASA Astrophysics Data System (ADS)

The extraction of soluble materials from organic samples plays an important role in many industries. For example, extraction of oils and grease from soil samples using traditional Soxhlet extractors is an essential procedure in waste management laboratories. These extractors use from 25 to 1000 mL of solvent per sample and the waste solvent is typically distilled or simply disposed of upon completion of the extraction. To minimize the waste solvent produced, we have developed a microscale continuous hot solvent extractor that effectively extracts 100-500-mg samples using about 4 mL of solvent.

Wesolowski, Steve S.; Mulcahy, Thomas; Zafoni, Christina M.; Wesolowski, Wayne E.

1999-08-01

411

Batch extracting process using magnetic particle held solvents  

DOEpatents

A process is described 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. 5 figs.

Nunez, L.; Vandergrift, G.F.

1995-11-21

412

Evaluation of solvent selectivity in dewaxing and deoiling  

SciTech Connect

Previous literature on the efficiency of solvents used in removing paraffin wax by decrystallization is insufficient. A method for evaluating selectivity and mixtures of solvents is offered. General solvents MEK, acetone, MIBK are tested in various raw materials, then graphed. It is found that the ratio of the slope of the curve for the temperature of equal solubility (TES) as a function of the content of the solvent (that is, the solubility curve) to the slope of the corresponding denormalization curve is constant. This ratio gives a formula, and is therefore a criterion for selectivity. The greater the ratio, the higher the selectivity. The ratio is also generalized to solvents of any composition.

Al'perovich, N.V.; Leonidov, A.N.; Sokolova, S.P.

1983-05-01

413

Recent research on care coordination.  

PubMed

Patients with multiple chronic conditions have been shown to have significant Medicare expenditures. Care coordination programs have been implemented targeting this population by organizations striving to achieve the triple aim of (a) improving healthcare quality, (b) improving the patient experience, and (c) reducing costs. Outcomes of these programs have been mixed. This research brief profiles four published articles that address different aspects of care coordination. Readers are encouraged to access the full articles to learn more details about the intervention strategies and findings described in these articles. PMID:25654460

Rocks, Donna; Cooper-Audain, Elizer

2015-02-01

414

Sequential accelerated solvent extraction of polycyclic aromatic hydrocarbons with different solvents: performance and implication.  

PubMed

Sixteen USEPA priority polycyclic aromatic hydrocarbons (PAHs) extracted by Soxhlet extraction (S-PAHs) with dichloromethane and routine accelerated solvent extraction (A-PAHs) with 1:1 toluene/methanol, respectively, were investigated in 24 soil samples from two cities in the center of the Pearl River Delta, South China. Polycyclic aromatic hydrocarbons, methylphenanthrene and perylene, in two soils, two sediments, and an immature oil shale were also sequentially extracted by accelerated solvent extraction (ASE) with each of four different organic solvents for three times. The A-PAHs' concentrations are 2.41 times the S-PAHs' concentrations. For sequential three ASEs, PAHs in the first extract account for 56 to 67% of their total concentrations in the sequential three extractions and toluene displays the best extraction performance among the four solvents. Diagnostic ratios of PAHs in Soxhlet extraction, routine ASE, and sequential ASE with each solvent for a given sample are very similar, suggesting their identical petrogenic and pyrogenic sources in the soils and sediments. But the PAH ratios for the shale have an obvious petrogenic origin. The perylene/5-ring PAH ratios indicate a diagenetic source, especially in the shale and sediments. The correlation analysis shows that A-PAHs/S-PAHs is better associated with the contents of total organic carbon (TOC) than those of black carbon (BC). The above results indicate the significant petrogenic origin of PAHs and the important effect of organic matter on their extraction and distribution in the investigated field soils/sediments. PMID:21284305

Ma, Xiaoxuan; Ran, Yong; Gong, Jian; Chen, Diyun

2010-01-01

415

Excited state properties of chlorophyll f in organic solvents at ambient and cryogenic temperatures.  

PubMed

Chlorophyll f is a photosynthetic pigment that was discovered in 2010. In this study, we present investigations on spectral and dynamic characteristics of singlet-excited and triplet states of Chl f with the application of ultrafast time-resolved absorption and fluorescence spectroscopies. The pigment was studied at room temperature in two organic solvents: pyridine and diethyl ether that have different characters of coordination of the chlorophyll magnesium (Mg) atom (hexa- and penta-coordination, respectively). Cryogenic measurements (77 K) were performed in 2-methyltetrahydrofuran (hexa-coordination). The singlet-excited state lifetime was measured to be 5.6 ns at room temperature regardless of Mg coordination and 8.1 ns at 77 K. The fluorescence quantum yield of Chl f was also determined in pyridine to be 0.16. The triplet state lifetime was studied in detail in pyridine at room temperature, and the inherent lifetime was estimated to ~150 ?s. Selective measurements at 77 K demonstrated that the metastability of the triplet state greatly enhances, and its lifetime increases by a factor of more than three. PMID:24549930

Niedzwiedzki, Dariusz M; Liu, Haijun; Chen, Min; Blankenship, Robert E

2014-07-01

416

Reactive Tuple Spaces for Mobile Agent Coordination  

Microsoft Academic Search

Mobile active computational entities introduce peculiar problems in the coordination o f distributed app lication components. The paper s urveys s everal coordination models for mobile agent applications and outlines the advantages of uncoupled coordination models based on reactive blackboards. On this base, the paper presents the design and the implementation o f the MARS system, a coordination tool for

Giacomo Cabri; Letizia Leonardi; Franco Zambonelli

1998-01-01

417

Nonhazardous solvent composition and method for cleaning metal surfaces  

DOEpatents

A solvent composition for displacing greasy and oily contaminants as well as water and/or aqueous residue from metallic surfaces, especially surfaces of radioactive materials so that such surfaces can be wiped clean of the displaced contaminants, water and/or aqueous residue. The solvent composition consists essentially of a blend of nonpolar aliphatic hydrocarbon solvent having a minimum flash point of about 140 F and 2 to 25 volume percent of a polar solvent having a flash point sufficiently high so as to provide the solvent composition with a minimum flash point of at least 140 F. The solvent composition is nonhazardous so that when it is used to clean the surfaces of radioactive materials the waste in the form of paper or cloth wipes, lab coats and the like used in the cleaning operation is not considered to be mixed waste composed of a hazardous solvent and a radioactive material.

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

1993-05-04

418

Nonhazardous solvent composition and method for cleaning metal surfaces  

DOEpatents

A solvent composition for displacing greasy and oily contaminants as well as water and/or aqueous residue from metallic surfaces, especially surfaces of radioactive materials so that such surfaces can be wiped clean of the displaced contaminants, water and/or aqueous residue. The solvent composition consists essentially of a blend of nonpolar aliphatic hydrocarbon solvent having a minimum flash point of about 140.degree. F. and 2 to 25 volume percent of a polar solvent having a flash point sufficiently high so as to provide the solvent composition with a minimum flash point of at least 140.degree. F. The solvent composition is nonhazardous so that when it is used to clean the surfaces of radioactive materials the waste in the form of paper or cloth wipes, lab coats and the like used in the cleaning operation is not considered to be mixed waste composed of a hazardous solvent and a radioactive material.

Googin, John M. (Oak Ridge, TN); Simandl, Ronald F. (Farragut, TN); Thompson, Lisa M. (Knoxville, TN)

1993-01-01

419

Contributions of silane cross-linked PEX pipe to chemical/solvent odours in drinking water.  

PubMed

A commonly used plastic plumbing pipe, silane-cross-linked polyethylene (PEX-b according to European standards), was investigated using the Utility Quick Test (UQT), which is a migration/leaching protocol recommended for evaluating taste-and-odour properties of materials prior to installation in distribution systems. After exposure of new PEX pipe to chlorine, monochloramine or no disinfectant, the odours in the leachate were described as "chlorinous" if chlorine or monochloramine were present and "chemical/solvent-like" with descriptors of sweet, bitter, chemical, solvent, plastic, burnt and mechanical/motor oil. The presence of disinfectant, chlorine or chloramines, did not alter the odour characteristics or intensity of the PEX odour. The "chemical/solvent-like" odours persisted even after multiple flushing periods. 2-Ethoxy-2-methylpropane, commonly called ETBE, was identified as a contributor to the described odour from the PEX pipe. Aqueous concentrations of ETBE in pipe leachate ranged from a low of 23 microg/L to > 100 microg/L. The concentrations decreased with increased flushing. Panelists were able to smell ETBE at a concentration of 5 microg/L and assigned a rating of a weak odour. The need for taste and odour testing of plumbing materials prior to use in residential housing systems is necessary. PMID:17489405

Durand, M L; Dietrich, A M

2007-01-01

420

1,2-diacetylbenzene, the neurotoxic metabolite of a chromogenic aromatic solvent, induces proximal axonopathy.  

PubMed

Several widely used aromatic hydrocarbon solvents reportedly induce blue-green discoloration of tissues and urine in animals and humans. The chomophore has been proposed to result from a ninhydrin-like reaction with amino groups in proteins. The present study examines the neurotoxic property of 1,2-diacetylbenzene (1,2-DAB), the active metabolite of the chromogenic and neurotoxic aromatic solvent 1,2-diethylbenzene. Rats treated with 1,2-DAB, but not with the nonchromogenic isomer 1,3-DAB or with ninhydrin developed blue discoloration of internal organs, including the brain and spinal cord. Only 1,2-DAB induced limb weakness associated with nerve fiber changes, which were most prominent in spinal cord and spinal roots. Changes began with the formation of proximal, neurofilament-filled axonal swellings of the type seen after treatment with 3,4-dimethyl-2,5-hexanedione, a potent derivative of the active metabolite of the neurotoxic aliphatic hydrocarbon solvents n-hexane and methyl n-butyl ketone. These compounds are metabolized to a gamma-diketone that forms pyrroles with target proteins, such as neurofilament proteins. A comparable mechanism is considered for 1,2-DAB, an aromatic gamma-diketone. PMID:11740911

Kim, M S; Sabri, M I; Miller, V H; Kayton, R J; Dixon, D A; Spencer, P S

2001-12-01

421

Water structure in vitamin B12 coenzyme crystals. II. Structural characteristics of the solvent networks.  

PubMed Central

The geometrical details of the solvent structure in vitamin B12 coenzyme crystals with respect to hydrogen bonding and nonbonded contacts, are described. The individual H-bond geometries varied over wide ranges, similar to those observed in small molecule structures. Large deviations from tetrahedral coordination were found around a majority of the waters. The mutual positions and orientations of the water molecules could not be adequately explained in terms of the H-bonding relationships present in the structure. However, additional investigations, which focused on the short range nonbonded contacts around water positions in a variety of crystal hydrates, revealed several structural regularities (Savage, 1986b). These features relate to the nonbonded O...O, H...O, and H...H interactions, and give rise to a set of repulsive restrictions that are seen to be very much stronger stereochemical restraints than those associated with H-bonding. The short-range restrictions appear largely to govern the local orientational correlations and packing arrangements of the water structure within the coenzyme (and other hydrate) crystals. In more general terms, the inclusion of the nonbonding relationships as well as the attractive H-bonding interactions, leads to a significant increase in our understanding of water structure(s). The repulsive restrictions can be used as stereochemical restraints in the interpretation and refinement of solvent structures within larger hydrate systems, such as protein crystals. They may also be included in potential functions used to simulate solvent structures in aqueous solutions and hydrate systems. PMID:3790697

Savage, H

1986-01-01

422

Single Stage Contactor Testing Of The Next Generation Solvent Blend  

SciTech Connect

The Modular Caustic Side Solvent Extraction (CSSX) Unit (MCU) facility at the Savannah River Site (SRS) is actively pursuing the transition from the current BOBCalixC6 based solvent to the Next Generation Solvent (NGS)-MCU solvent to increase the cesium decontamination factor. To support this integration of NGS into the MCU facility the Savannah River National Laboratory (SRNL) performed testing of a blend of the NGS (MaxCalix based solvent) with the current solvent (BOBCalixC6 based solvent) for the removal of cesium (Cs) from the liquid salt waste stream. This testing utilized a blend of BOBCalixC6 based solvent and the NGS with the new extractant, MaxCalix, as well as a new suppressor, tris(3,7dimethyloctyl) guanidine. Single stage tests were conducted using the full size V-05 and V-10 liquid-to-liquid centrifugal contactors installed at SRNL. These tests were designed to determine the mass transfer and hydraulic characteristics with the NGS solvent blended with the projected heel of the BOBCalixC6 based solvent that will exist in MCU at time of transition. The test program evaluated the amount of organic carryover and the droplet size of the organic carryover phases using several analytical methods. The results indicate that hydraulically, the NGS solvent performed hydraulically similar to the current solvent which was expected. For the organic carryover 93% of the solvent is predicted to be recovered from the stripping operation and 96% from the extraction operation. As for the mass transfer, the NGS solvent significantly improved the cesium DF by at least an order of magnitude when extrapolating the One-stage results to actual Seven-stage extraction operation with a stage efficiency of 95%.

Herman, D. T.; Peters, T. B.; Duignan, M. R.; Williams, M. R.; Poirier, M. R.; Brass, E. A.; Garrison, A. G.; Ketusky, E. T.

2014-01-06

423

Experimental solution thermodynamics of a ternary solvent/polymer/solvent system by inverse gas chromatography / by Dominic Wai Wah Ching  

E-print Network

38 39 INTRODUCTION Many polymers which are not readily soluble in a single solvent can be processed in a mixture of solvents. In addition, many polymers with desirable high-temperature properties must be processed in strongly acidic solvents... x12 2 ~) + ? + (~ x + ~ x )(~+a ) 2 x12 y 2 12 3 1$ 2 32 of the cohesive-energy density. If a polymer and a series of solvents have similar polarity, the polymer is soluble only in those solvents whose cohesive-energy density is not too...

Ching, Dominic Wai Wah

2012-06-07

424

Sequential Synthesis of Coordination Polymersomes.  

PubMed

Novel organic-inorganic hybrid liposomes, so-called coordination polymersomes (CPsomes), with artificial domains that exhibit strong lateral cohesion were prepared by a three-step procedure that formed a coordinative interaction leading to a lipid bilayer. First, the lipophilic complex (dabco-C18 )[Mn(N)(CN)4 (dabco-C18 )] (1; dabco-C18 (+) =1,4-diazabicyclo[2,2,2]octane-(CH2 )17 ?CH3 cation), was synthesized. 1 has a lipophilic alkyl tail part and a tetracyanometallate head group, which can be used for an expansion to two-dimensional coordination networks. Second, 1 and 1,2-dipalmitoyl-sn-glycero-3-phosphocholine were mixed to prepare the liposomes. Finally, CPsomes were obtained by the addition of transition-metal ions (M) to form unilamellar faceted liposomes with plain CP raft domains with Mn?CN?M linkages. The concentration of 1 influences the size of the CP raft domains and the shape of the CPsomes. The synthesis of coordination polymers in lipid bilayers is a novel approach for the construction of artificial architectures as raft domains, for example, in cell membranes. PMID:25476115

Ohtani, Ryo; Inukai, Munehiro; Hijikata, Yuh; Ogawa, Tetsuya; Takenaka, Mikihito; Ohba, Masaaki; Kitagawa, Susumu

2014-12-01

425

Terrestrial Coordinate Systems and Frames  

NASA Astrophysics Data System (ADS)

A terrestrial reference system (TRS) is a spatial reference system corotating with the Earth in its DIURNAL MOTION in space. In such a system, the positions of points anchored on the Earth's solid surface have coordinates which have only small variations with time, as a result of geophysical effects (tectonic or tidal deformations; see TECTONICS, EARTH'S INTERIOR, TIDES). A terrestrial reference ...

Boucher, C.; Murdin, P.

2000-11-01

426

Co-ordinated Classroom Lectures.  

ERIC Educational Resources Information Center

From a series of lectures, a selection of eight are oriented principally toward the biologically developing child, and the physiological operations in visual process. The numbered lectures are--(1) The Coordinated Classroom, its Philosophy and Principles, (2) An Outline of a Biological Point of View, (3) The Evolution of Structure--despite man's…

Harmon, Darell Boyd

427

North America Coordinating Lead Authors  

E-print Network

14 North America Coordinating Lead Authors: Christopher B. Field (USA), Linda D. Mortsch (Canada and M.J. Scott, 2007: North America. Climate Change 2007: Impacts, Adaptation and Vulnerability University Press, Cambridge, UK, 617-652. #12;North America Chapter 14 618 Executive summary

428

BURN DATA COORDINATING CENTER (BDCC)  

EPA Science Inventory

The Burn Data Coordinating Center (BDCC) began collecting data in 1994 and is currently the largest burn database in the country. Pediatric burn data was added in 1998. The BMS database contains over 2,800 cases supporting clinical research and research on outcomes including empl...

429

Job Announcement Development Database Coordinator  

E-print Network

in the United States. The Holden Arboretum / Cleveland Botanical Garden has an opportunity for a Development. The Database Coordinator manages and maintains Holden's / Cleveland Botanical Garden's confidential donor Filled The Holden Arboretum / Cleveland Botanical Garden is an equal opportunity, ADA employer and a drug

Isaacs, Rufus

430

Archimedes' Principle in General Coordinates  

ERIC Educational Resources Information Center

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…

Ridgely, Charles T.

2010-01-01

431

International Space Exploration Coordination Group  

E-print Network

for collaborative space exploration missions beginning with the International Space Station (ISS) and continuingInternational Space Exploration Coordination Group The Global Exploration Roadmap August 2013 #12 The Global Exploration Roadmap is being developed by space agencies participating in the International Space

Rathbun, Julie A.

432

Redox-induced change in the ligand coordination mode.  

PubMed

The reaction of cobalt(II) pivalate with a spin-labeled Schiff base (HL(1)) in organic solvents formed trinuclear complex [Co3(Piv)2L(1)2L(2)2]·Solv (Solv is Me2CO and/or C7H16 and CH3CN) containing both nitroxide L(1) and the product of its single-electron reduction, nitrone L(2). The formation of [Co3(Piv)2L(1)2L(2)2] was a consequence of an unusual phenomenon, which we called "redox-induced change in the ligand coordination mode". A reduction of L(1) to L(2) led to a change in the set of donor atoms and even in the size of the metallocycle. This phenomenon was also found for mononuclear [CrL(1)2L(2)] and [FeL(1)2L(2)]·Me2CO. PMID:25215863

Ovcharenko, Victor; Kuznetsova, Olga; Fursova, Elena; Romanenko, Galina; Polushkin, Alexey; Sagdeev, Renad

2014-10-01

433

Refractive index measured by laser beam displacement at {lambda}=1064 nm for solvents and deuterated solvents  

SciTech Connect

The refractive index of a liquid is determined with 0.0003 accuracy from measurements of laser beam displacement by a liquid-filled standard 10 mm spectrophotometer cell. The apparatus and methods are described and the results of measurements at {lambda}=1064 nm and T=25.0 deg. C for 30 solvents and deuterated solvents are presented. Several sources of potential systematic errors as large as 0.003 are identified, the most important being the curvature of the liquid cell windows. The measurements are analyzed accounting for the significant imperfections of the apparatus.

Shelton, David P.

2011-07-20

434

Scenarios Evaluation Tool for Chlorinated Solvent MNA  

SciTech Connect

Over the past three decades, much progress has been made in the remediation of chlorinated solvents from the subsurface. Yet these pervasive contaminants continue to present a significant challenge to the U.S. Department of Energy (DOE), other federal agencies, and other public and private organizations. The physical and chemical properties of chlorinated solvents make it difficult to rapidly reach the low concentrations typically set as regulatory limits. These technical challenges often result in high costs and long remediation time frames. In 2003, the DOE through the Office of Environmental Management funded a science-based technical project that uses the U.S. Environmental Protection Agency's technical protocol (EPA, 1998) and directives (EPA, 1999) on Monitored Natural Attenuation (MNA) as the foundation on which to introduce supporting concepts and new scientific developments that will support remediation of chlorinated solvents based on natural attenuation processes. This project supports the direction in which many site owners want to move to complete the remediation of their site(s), that being to complete the active treatment portion of the remedial effort and transition into MNA. The overarching objective of the effort was to examine environmental remedies that are based on natural processes--remedies such as Monitored Natural Attenuation (MNA) or Enhanced Attenuation (EA). The research program did identify several specific opportunities for advances based on: (1) mass balance as the central framework for attenuation based remedies, (2) scientific advancements and achievements during the past ten years, (3) regulatory and policy development and real-world experience using MNA, and (4) exploration of various ideas for integrating attenuation remedies into a systematic set of ''combined remedies'' for contaminated sites. These opportunities are summarized herein and are addressed in more detail in referenced project documents and journal articles, as well as in the technical and regulatory documents being developed within the ITRC.

Vangelas, Karen; Michael J. Truex; Charles J. Newell; Brian Looney

2007-02-28

435

Solvent isotope effects on nucleophilic displacement reactions  

SciTech Connect

The kinetic solvent isotope effect, KSIE, (k/sub H/sub 2/O//k/sub D/sub 2/O/), at 25.0/sup 0/C and ionic strength, I, equal to 0.20 +- 0.02 M was measured for the nucleophilic displacement of iodine ion from iodomethane, iodoacetamide, and iodoacetate ion, thiophene from S-Methylthiophenium ion, and tosylate ion from methyl tosylate by bromide ion, chloride ion, acetate ion, hydroxide ion, water, ammonia, ethylenediamine, n-butylamine, piperazine, piperidine, quinuclidine, and 1,4-Diazabicyclo(2.2.2)octane (DABCO), and the monoprotonated cations of ethylenediamine, piperazine, and DABCO. By means of solvent partition measurements at 25.0/sup 0/C and I = 0.02 M between H/sub 2/O and D/sub 2/O and a common immiscible organic solvent, the ground state activity coefficients in D/sub 2/O, the solution in H/sub 2/O being chosen as the reference state, were determined for the nitrogen-containing nucleophiles (except ammonia) and the substrates methyl tosylate, iodoacetamide, and iodoacetic acid. The solubilities at 25.0/sup 0/C of the picrate and tetraphenylborate salts of the monoprotonated cationic forms of ethylenediamine, piperazine, and DABCO were measured to determine the activity coefficients in D/sub 2/O of these ions relative to an H/sub 2/O reference state. Applying the Eyring equation, the activity coefficients of the transition states in D/sub 2/O, reference state H/sub 2/O, were calculated.

Spiegel, G.W.

1981-01-01

436

A series of weak ferromagnets based on a chromium-acetylide-TTF type complex: correlation of the structures and magnetic properties and origin of the weak ferromagnetism.  

PubMed

The crystal structures and magnetic properties of a series of new weak ferromagnets containing a chromium-acetylide-tetrathiafulvalene (TTF) type complex, [CrCyclam(C?C-5-methyl-4'5'-ethylenedithio-TTF)2](2+) ([1](2+)), were investigated. The six new isostructural weak ferromagnets [1][BF4]2(PhF)2(MeCN), [1][ClO4]2(PhF)2(MeCN), [1][ReO4]2(PhCl)2(MeCN), [1][ClO4]2(PhBr)3, [1][ReO4]2(PhBr)3, and [1][ClO4]2(PhI)3 contain ferrimagnetic chain structures of [1](2+)? with different interchain distances that are dependent on the sizes of the anions and solvent molecules. Magnetic measurements of the salts revealed that the weak ferromagnetic transition temperature gradually increases from 14.5 to 26.0 K as the interchain distance decreases from 3.997(2) to 3.803(2) Å, while the remanent magnetization at 2 K decreases from 0.0215 to 0.0079 ?B. The observed magnetic properties and crystal structures suggest that the weak ferromagnetism originates from the single-ion anisotropy of [1](2+), where a stronger interchain antiferromagnetic interaction not only causes a higher transition temperature but also suppresses the noncollinear canted spin alignment. PMID:24161267

Nishijo, Junichi; Enomoto, Masaya

2013-11-18

437

Membrane separation of hydrocarbons using cycloparaffinic solvents  

DOEpatents

Heavy crude oils which contain metal contaminants such as nickel, vanadium and iron may be separated from light hydrocarbon oils by passing a solution of the crude oil dissolved in a cycloparaffinic hydrocarbon solvent containing from about 5 to about 8 carbon atoms by passing through a polymeric membrane which is capable of maintaining its integrity in the presence of hydrocarbon compounds. The light hydrocarbon oils which possess relatively low molecular weights will be recovered as the permeate while the heavy oils which possess relatively high molecular weights as well as the metal contaminants will be recovered as the retentate.

Kulkarni, S.S.; Chang, Y.A.; Gatsis, J.G.; Funk, E.W.

1988-06-14

438

Universal solvent restructuring induced by colloidal nanoparticles.  

PubMed

Colloidal nanoparticles, used for applications from catalysis and energy applications to cosmetics, are typically embedded in matrixes or dispersed in solutions. The entire particle surface, which is where reactions are expected to occur, is thus exposed. Here, we show with x-ray pair distribution function analysis that polar and nonpolar solvents universally restructure around nanoparticles. Layers of enhanced order exist with a thickness influenced by the molecule size and up to 2 nanometers beyond the nanoparticle surface. These results show that the enhanced reactivity of solvated nanoparticles includes a contribution from a solvation shell of the size of the particle itself. PMID:25593188

Zobel, Mirijam; Neder, Reinhard B; Kimber, Simon A J

2015-01-16

439

Dynamics of Charged Colloids in Nonpolar Solvents  

NASA Astrophysics Data System (ADS)

Charging is typically not expected in nonpolar environments due to a high electrostatic barrier to charge dissociation. Nevertheless, charge effects are observed in such environments upon the addition of surfactants, which aggregate to form charge-stabilizing reverse micelles. Surfactants facilitate the charging and electrostatic stabilization of particles dispersed in nonpolar solvents. Suspensions of charged particles in nonpolar solvents are found in a variety of applications, such as electrophoretic displays, in which charged pigment particles are arranged with an external electric field to form an image. The ability to precisely control the locations and trajectories of the particles using an electric field is essential. However, the behavior of charged particles in a nonpolar solvent in response to an electric field is not fully understood. To investigate the behavior of charged particles in nonpolar solvents, we fabricate a novel microfluidic device that allows us to apply an electric field across a particle suspension and directly visualize the particles as they move across a channel. We image the particles, analyze the particle dynamics, and explore the relationship between the dynamics and the electrical properties of the suspension. We find that the presence of reverse micelles has a significant effect on particle motion. In a constant applied electric field, the particles initially move, but then unexpectedly slow down and stop. This behavior is due to screening of the applied field by the accumulation of charged reverse micelles at the channel walls. Consequently, the internal electric field within the channel decays exponentially. The decay time constant is dependent on the electrical conductivity of the suspension and the size of the channel. We model this behavior as an equivalent RC circuit. We also explore the behavior of charged particles in applied fields that are large enough to transport the particles completely across the channel. We find that the transport of particles is governed by a fingering instability. Furthermore, repeated switches of the direction of the field results in the localization of particles into a well-defined, periodic pattern. The wavelength of this pattern is dependent on the frequency of the applied field.

Lin, Tina

440

Membrane separation of hydrocarbons using cycloparaffinic solvents  

DOEpatents

Heavy crude oils which contain metal contaminants such as nickel, vanadium and iron may be separated from light hydrocarbon oils by passing a solution of the crude oil dissolved in a cycloparaffinic hydrocarbon solvent containing from about 5 to about 8 carbon atoms by passing through a polymeric membrane which is capable of maintaining its integrity in the presence of hydrocarbon compounds. The light hydrocarbon oils which possess relatively low molecular weights will be recovered as the permeate while the heavy oils which possess relatively high molecular weights as well as the metal contaminants will be recovered as the retentate.

Kulkarni, Sudhir S. (Hoffman Estates, IL); Chang, Y. Alice (Westmont, IL); Gatsis, John G. (Des Plaines, IL); Funk, Edward W. (Highland Park, IL)

1988-01-01

441

Mixed solvent system for treating acidic gas  

SciTech Connect

This invention discloses mixtures of alkyl dialcohol amines and mono alkyl ethers of polyethylene glycols which are useful in removing acidic gases from gaseous mixtures. The solvent mixtures contain between 1.5 N and 5.0 N methyl diethanolamine (MDEA), 10 to 40 percent water and the balance is methoxytriglycol (MTG). The overall heat of reaction of the solution is typically less than 500 BTU/lb CO/sub 2/, and remains as a single liquid phase during normal gas scrubber operating conditions.

Capobianco, P.J.; Butwell, K.F.; Kossakowski, E.J.

1987-11-10

442

A Universe without Weak Interactions  

SciTech Connect

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.

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

2006-04-07

443

Work as coordination and coordination as work: A process perspective on FLOSS development projects  

E-print Network

Work as coordination and coordination as work: A process perspective on FLOSS development projects Dipartimento Impresa e Lavoro Università degli Studi di Cassino Cassino Italy #12;Work as coordination and coordination as work: A process perspective on FLOSS development projects Abstract Coordination in work teams

Crowston, Kevin

444

Enhanced performance of dicationic ionic liquid electrolytes by organic solvents.  

PubMed

The use of dicationic ionic liquid (DIL) electrolytes in supercapacitors is impeded by the slow dynamics of DILs, whereas the addition of organic solvents into DIL electrolytes improves ion transport and then enhances the power density of supercapacitors. In this work, the influences of organic solvents on the conductivity of DILs and the electrical double layer (EDL) of DIL-based supercapacitors are investigated using classical molecular dynamics simulation. Two types of organic solvents, acetonitrile (ACN) and propylene carbonate (PC), were used to explore the effects of different organic solvents on the EDL structure and capacitance of DIL/organic solvent-based supercapacitors. Firstly, it was found that the conductivity of DIL electrolytes was greatly enhanced in the presence of the organic solvent ACN. Secondly, a stronger adsorption of PC on graphite results in different EDL structures formed by DIL/ACN and DIL/PC electrolytes. The expulsion of co-ions from EDLs was observed in DIL/organic solvent electrolytes rather than neat DILs and this feature is more evident in DIL/PC. Furthermore, the bell-shaped differential capacitance-electric potential curve was not essentially changed by the presence of organic solvents. Comparing DIL/organic solvent electrolytes with neat DILs, the capacitance is slightly increased by organic solvents, which is in agreement with experimental observation. PMID:24920237

Li, Song; Zhang, Pengfei; Fulvio Pasquale, F; Hillesheim Patrick, C; Feng, Guang; Dai, Sheng; Cummings Peter, T

2014-07-16

445

A luminescent coordination polymer based on bisterpyridyl ligand containing o-carborane: two tunable emission modes.  

PubMed

We designed a novel ditopic bisterpyridyl ligand containing o-carborane that can construct a coordination polymer by complexation with metal ions. Through the use of Sonogashira-Hagihara coupling, the desired ligand molecule was successfully synthesized. Addition of Zn(II) ions rapidly underwent the generation of a fluorescent coordination polymer, which was confirmed by (1)H NMR, UV-vis, and fluorescent titration experiments. Furthermore, the electronic structure of the bisterpyridyl ligand molecules was drastically changed upon the complexation with metal ions. The obtained coordination polymer showed light blue emission derived from the intraligand charge transfer (ILCT) state, whereas a bare ligand molecule exhibited yellowish-green aggregation-induced emission (AIE) in a poor solvent such as water, because of the variable C-C bond in o-carborane. PMID:21258739

Kokado, Kenta; Chujo, Yoshiki

2011-03-01

446

A two-coordinate boron cation featuring C-B+-C bonding  

NASA Astrophysics Data System (ADS)

Two-coordinate boron cations (R2B+), referred to as borinium ions, are chemical species in which the boron bears only four valence electrons, and that are isoelectronic with hypothetical carbon dications (R2C2+). Although lone-pair-donating substituents such as amino groups have enabled the isolation of several borinium ions, diarylated and dialkylated borinium derivatives remain entirely unexplored. Here, we present the synthesis, structure and reactivity of the dimesitylborinium ion, which displays unexpectedly high thermal stability. X-ray crystallography and 11B NMR spectroscopy, supported by density functional theory calculations, reveal that the borinium ion adopts a linear two-coordinate structure in both the solid state and in solution. The boron centre is stabilized by p? bonding from the mesityl groups and is free from coordination by the counterion or solvent molecules. This diarylborinium ion possesses exceptional Lewis acidity, accepting a pair of electrons from CO2 to cause an unusual deoxygenation reaction.

Shoji, Yoshiaki; Tanaka, Naoki; Mikami, Koichiro; Uchiyama, Masanobu; Fukushima, Takanori

2014-06-01

447

Numerical test of weak turbulence theory  

NASA Technical Reports Server (NTRS)

The analytic theory of weak Langmuir turbulence is well known, but very little has previously been done to compare its predictions with numerical solutions of the basic dynamical evolution equations. In this paper, numerical solutions of the statistical weak turbulence theory are compared with numerical solutions of the Zakharov model of Langmuir turbulence, and good agreement in certain regimes of very weak field strength is found.

Payne, G. L.; Nicholson, D. R.; Shen, Mei-Mei

1989-01-01

448

Effect of organic solvents on particle size of Mn{sub 3}O{sub 4} nanoparticles synthesized by a solvothermal method  

SciTech Connect

In this paper, a modified simple solvothermal method is employed to synthesize Mn{sub 3}O{sub 4} nanocrystals using four different solvents: acetone, ethanol, N,N-dimethylformamide (DMF), and dimethyl sulfoxide (DMSO). Mn{sub 3}O{sub 4} nanoparticles with a tetragonal hausmannite nano-structure are characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), Fourier transform infrared spectroscopy (FTIR), as well as superconducting quantum interference device magnetometer (SQUID). The Mn{sub 3}O{sub 4} particle size is found to have a strong dependency on the solvent used. A reaction scheme is proposed to understand this dependency, suggesting that the solvent coordinating capability has a critical effect on Mn{sub 3}O{sub 4} particle size. The stronger the coordinating capability of the solvent is, the smaller the Mn{sub 3}O{sub 4} particle size is. In addition, magnetic properties of the nano-structured Mn{sub 3}O{sub 4} are also tested and discussed. - Graphical abstract: The comparison of the particle size of Mn{sub 3}O{sub 4} nanoparticles synthesized using different solvents and HRTEM image of Mn{sub 3}O{sub 4} individual nanoparticle revealed its single-crystal nature. - Highlights: • Mn{sub 3}O{sub 4} nanocrystals were synthesized using different solvents by a solvothermal method. • The particle size of Mn{sub 3}O{sub 4} nanocrystal is found to have a strong dependency on the solvent used. • A reaction mechanism is proposed to explain the difference of particle size of Mn{sub 3}O{sub 4} nanocrystals. • Magnetic properties of Mn{sub 3}O{sub 4} nanocrystals with different particle size are tested and compared.

Song, Rui [Research Institute, Jilin Petrochemical Company Ltd., Jilin 132021 (China); Feng, Shouhua, E-mail: shfeng@mail.jlu.edu.cn [State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, College of Chemistry, Jilin University, Changchun 130012 (China); Wang, Hongjun [Sales and Management Department, Jilin Petrochemical Company Ltd., Jilin 132002 (China); Hou, Changmin [State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, College of Chemistry, Jilin University, Changchun 130012 (China)

2013-06-15

449

Weak measurements with a qubit meter  

E-print Network

We derive schemes to measure the so-called weak values of quantum system observables by coupling of the system to a qubit meter system. We highlight, in particular, the meaning of the imaginary part of the weak values, and show how it can be measured directly on equal footing with the real part of the weak value. We present compact expressions for the weak value of single qubit observables and of product observables on qubit pairs. Experimental studies of the results are suggested with cold trapped ions.

Shengjun Wu; Klaus Mølmer

2009-09-04

450

Pseudo-Weak-R0 Algebras  

PubMed Central

A positive answer to the open problem of Iorgulescu on extending weak-R0 algebras and R0-algebras to the noncommutative forms is given. We show that pseudo-weak-R0 algebras are categorically isomorphic to pseudo-IMTL algebras and that pseudo-R0 algebras are categorically isomorphic to pseudo-NM algebras. Some properties, the noncommutative forms of the properties in weak-R0 algebras and R0-algebras, are investigated. The simplified axiom systems of pseudo-weak-R0 algebras and pseudo-R0 algebras are obtained. PMID:25302322

Liu, Yong Lin; Cai, Xiaobo

2014-01-01

451

Anomalous Weak Values Are Proofs of Contextuality  

NASA Astrophysics Data System (ADS)

The average result of a weak measurement of some observable A can, under postselection of the measured quantum system, exceed the largest eigenvalue of A . The nature of weak measurements, as well as the presence of postselection and hence possible contribution of measurement disturbance, has led to a long-running debate about whether or not this is surprising. Here, it is shown that such "anomalous weak values" are nonclassical in a precise sense: a sufficiently weak measurement of one constitutes a proof of contextuality. This clarifies, for example, which features must be present (and in an experiment, verified) to demonstrate an effect with no satisfying classical explanation.

Pusey, Matthew F.

2014-11-01

452

A coordination theory for intelligent machines  

NASA Technical Reports Server (NTRS)

A formal model for the coordination level of intelligent machines is established. The framework of the coordination level investigated consists of one dispatcher and a number of coordinators. The model called coordination structure has been used to describe analytically the information structure and information flow for the coordination activities in the coordination level. Specifically, the coordination structure offers a formalism to (1) describe the task translation of the dispatcher and coordinators; (2) represent the individual process within the dispatcher and coordinators; (3) specify the cooperation and connection among the dispatcher and coordinators; (4) perform the process analysis and evaluation; and (5) provide a control and communication mechanism for the real-time monitor or simulation of the coordination process. A simple procedure for the task scheduling in the coordination structure is presented. The task translation is achieved by a stochastic learning algorithm. The learning process is measured with entropy and its convergence is guaranteed. Finally, a case study of the coordination structure with three coordinators and one dispatcher for a simple intelligent manipulator system illustrates the proposed model and the simulation of the task processes performed on the model verifies the soundness of the theory.

Wang, Fei-Yue; Saridis, George N.

1990-01-01

453

ACTIVE EFFLUX OF ORGANIC SOLVENTS BY PSEUDOMONAS PUTIDA S12 IS INDUCED BY SOLVENTS  

EPA Science Inventory

Induction of the membrane-associated organic solvent efflux system SrpABC of Pseudomonas putida S12 was examined by cloning a 312-bp DNA fragment, containing the srp promoter, in the broad-host-range reporter vector pKRZ-1. Compounds that are capable of inducing expression of the...

454

INVESTIGATION OF PLUTONIUM AND URANIUM UPTAKE INTO MCU SOLVENT AND NEXT GENERATION SOLVENT  

SciTech Connect

At the request of the Savannah River Remediation (SRR) customer, the Savannah River National Laboratory (SRNL) examined the plutonium (Pu) and uranium (U) uptake into the Next Generation Solvent (NGS) that will be used at the Salt Waste Processing Facility (SWPF). SRNL examined archived samples of solvent used in Extraction-Scrub-Strip (ESS) tests, as well as samples from new tests designed explicitly to examine the Pu and U uptake. Direct radiocounting for Pu and U provided the best results. Using the radiocounting results, we found that in all cases there were <3.41E-12 g Pu/g of NGS and <1.17E-05 g U/g of NGS in multiple samples, even after extended contact times and high aqueous:organic volume phase ratios. These values are conservative as they do not allow for release or removal of the actinides by scrub, strip, or solvent wash processes. The values do not account for extended use or any increase that may occur due to radiolytic damage of the solvent.

Peters, T.; Fink, S.

2012-01-06

455

Solvent tolerant marine bacterium Bacillus aquimaris secreting organic solvent stable alkaline cellulase.  

PubMed

The organic solvent tolerant bacteria with their physiological abilities to decontaminate the organic pollutants have potentials to secrete extracellular enzymes of commercial importance. Of the 19 marine bacterial isolates examined for their solvent tolerance at 10vol.% concentration, one had the significant tolerance and showed a relative growth yield of 86% for acetone, 71% for methanol, 52% for benzene, 35% for heptane, 24% for toluene and 19% for ethylacetate. The phylogenetic analysis of this strain using 16S rDNA sequence revealed 99% homology with Bacillus aquimaris. The cellulase enzyme secreted by this strain under normal conditions showed an optimum activity at pH 11 and 45°C. The enzyme did show functional stability even at higher pH (12) and temperature (75°C) with residual activity of 85% and 95% respectively. The enzyme activity in the presence of different additives were in the following order: Co(+2)>Fe(+2)>NaOCl(2)>CuSO(4)>KCl>NaCl. The enzyme stability in the presence of solvents at 20vol.% concentration was highest in benzene with 122% followed by methanol (85%), acetone (75%), toluene (73%) and heptane (42%). The pre-incubation of enzyme in ionic liquids such as 1-ethyl-3-methylimidazolium methanesulfonate and 1-ethyl-3-methylimidazolium bromide increased its activity to 150% and 155% respectively. The change in fatty acid profile with different solvents further elucidated the physiological adaptations of the strain to tolerate such extreme conditions. PMID:21388656

Trivedi, Nitin; Gupta, Vishal; Kumar, Manoj; Kumari, Puja; Reddy, C R K; Jha, Bhavanath

2011-04-01

456

Are deep eutectic solvents benign or toxic?  

PubMed

In continuation of investigation for environmentally benign protocol for new solvents termed deep eutectic solvents (DESs), it is herein reported results concerning the toxicity and cytotoxicity of choline chloride (ChCl) based DESs with four hydrogen bond donors including glycerine, ethylene glycol, triethylene glycol and urea. The toxicity was investigated using two Gram positive bacteria Bacillus subtilis and Staphylococcus aureus, and two Gram negative bacteria Escherichia coli and Pseudomonas aeruginosa. The cytotoxicity effect was tested using the Artemia salina leach. It was found that there was no toxic effect for the tested DESs on all of the studied bacteria confirming their benign effects on these bacteria. Nevertheless, it was found that the cytotoxicity of DESs was much higher than their individual components (e.g. glycerine, ChCl) indicating that their toxicological behavior is different. For our best knowledge this is the first time that toxicity and cytotoxicity of DESs were studied. The toxicity and cytotoxicity of DESs varied depending on the structure of components. Careful usage of the terms non-toxicity and biodegradability must be considered. More investigation on this matter is required. PMID:23200570

Hayyan, Maan; Hashim, Mohd Ali; Hayyan, Adeeb; Al-Saadi, Mohammed A; AlNashef, Inas M; Mirghani, Mohamed E S; Saheed, Olorunnisola Kola

2013-02-01

457

Tolerance of anaerobic bacteria to chlorinated solvents.  

PubMed

The aim of this research was to evaluate the effects of four chlorinated aliphatic hydrocarbons (CAHs), perchloroethene (PCE), carbon tetrachloride (CT), chloroform (CF) and 1,2-dichloroethane (1,2-DCA), on the growth of eight anaerobic bacteria: four fermentative species (Escherichia coli, Klebsiella sp., Clostridium sp. and Paenibacillus sp.) and four respiring species (Pseudomonas aeruginosa, Geobacter sulfurreducens, Shewanella oneidensis and Desulfovibrio vulgaris). Effective concentrations of solvents which inhibited growth rates by 50% (EC50) were determined. The octanol-water partition coefficient or log Po/w of a CAH proved a generally satisfactory measure of its toxicity. Most species tolerated approximately 3-fold and 10-fold higher concentrations of the two relatively more polar CAHs CF and 1,2-DCA, respectively, than the two relatively less polar compounds PCE and CT. EC50 values correlated well with growth rates observed in solvent-free cultures, with fast-growing organisms displaying higher tolerance levels. Overall, fermentative bacteria were more tolerant to CAHs than respiring species, with iron- and sulfate-reducing bacteria in particular appearing highly sensitive to CAHs. These data extend the current understanding of the impact of CAHs on a range of anaerobic bacteria, which will benefit the field of bioremediation. PMID:24441515

Koenig, Joanna C; Groissmeier, Kathrin D; Manefield, Mike J

2014-01-01

458

Recovery of plutonium from solvent wash solutions  

SciTech Connect

A number of potential alternatives to the acid hydrolysis recovery of Pu were investigated. The most promising alternative for short-term use appears to be an anion exchange process that would eliminate the long boiling times and the multiple-pass concentration steps needed with the solvent extraction process because it separates the Pu from the dibutyl phosphate (DBP) while at the same time concentrating the Pu. However, restart of the Primary Recovery Column (PRC) to process this solution would require significant administrative effort. The original boiling recovery by acid hydrolysis followed by solvent extraction is probably the most expedient way to process the Pu-DBP-carbonate solution currently stored in tank 13.5 even with its long processing times and dilute product concentration. Anion exchange of a heat stabilized acidified solution is a more efficient process, but requires restart of the PRC. Extended-boiling acid hydrolysis or anion exchange of a heat stabilized acidified solution provide two well developed alternatives for recovery of the Pu from the tank 13.5 carbonate. Further work defining additional recovery processes is not planned at this time.

Kyser, E.A.

1992-03-31

459

Tolerance of Anaerobic Bacteria to Chlorinated Solvents  

PubMed Central

The aim of this research was to evaluate the effects of four chlorinated aliphatic hydrocarbons (CAHs), perchloroethene (PCE), carbon tetrachloride (CT), chloroform (CF) and 1,2-dichloroethane (1,2-DCA), on the growth of eight anaerobic bacteria: four fermentative species (Escherichia coli, Klebsiella sp., Clostridium sp. and Paenibacillus sp.) and four respiring species (Pseudomonas aeruginosa, Geobacter sulfurreducens, Shewanella oneidensis and Desulfovibrio vulgaris). Effective concentrations of solvents which inhibited growth rates by 50% (EC50) were determined. The octanol-water partition coefficient or log Po/w of a CAH proved a generally satisfactory measure of its toxicity. Most species tolerated approximately 3-fold and 10-fold higher concentrations of the two relatively more polar CAHs CF and 1,2-DCA, respectively, than the two relatively less polar compounds PCE and CT. EC50 values correlated well with growth rates observed in solvent-free cultures, with fast-growing organisms displaying higher tolerance levels. Overall, fermentative bacteria were more tolerant to CAHs than respiring species, with iron- and sulfate-reducing bacteria in particular appearing highly sensitive to CAHs. These data extend the current understanding of the impact of CAHs on a range of anaerobic bacteria, which will benefit the field of bioremediation. PMID:24441515

Koenig, Joanna C.; Groissmeier, Kathrin D.; Manefield, Mike J.

2014-01-01

460

Communications indices of crew coordination  

NASA Technical Reports Server (NTRS)

Verbal exchanges occuring during task execution during full mission two-person simulator flights are used to study the effect of the interactive communication process on crew coordination and performance. The ratio of initiator to response speech is calculated and speech variations are recorded. The results of this study are compared with the findings of Ginnett's (1986) study of leaders. It is shown that low-error crews adopt a standard form of communicating, allowing for the ability to predict one another's behavior, facilitating the coordination process. The higher performance of crews that have flown together before is believed to be due to the increased amount of time for establishing a conventional means of communication.

Kanki, Barbara G.; Foushee, H. Clayton; Lozito, Sandra

1987-01-01

461

Complex coordinates in transformation optics  

SciTech Connect

We show that complex coordinates used in conjunction with transformation optics offer an extra degree of freedom that allows control over not only the propagation direction of electromagnetic waves but also their amplitude. We illustrate this idea in two applications. First, we show that in an n-dimensional space one can manipulate the field amplitude for up to n different amplitude distributions in regions that are critical to the performance of the device under consideration, and thus reduce the device's sensitivity to design imperfections in these regions. Second, we expand previous work on reflectionless perfectly matched layers and show how complex coordinates and transformation optics are a natural choice for designing perfectly matched layers of arbitrary shape.