These are representative sample records from Science.gov related to your search topic.
For comprehensive and current results, perform a real-time search at Science.gov.
1

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

PubMed

We have investigated the rotational dynamics of lithium thiocyanate (LiNCS) dissolved in various polar solvents with time and polarization resolved vibrational spectroscopy. LiNCS forms multiple distinct ionic structures in solution that can be distinguished with the CN stretch vibrational frequency of the different ionic assemblies. By varying the solvent and the LiNCS concentration, the number and type of ionic structures present in solution can be controlled. Control of the ionic structure provides control over the volume, shape, and dipole moment of the solute, critical parameters for hydrodynamic and dielectric continuum models of friction. The use of solutes with sizes comparable to or smaller than the solvent molecules also helps amplify the sensitivity of the measurement to the short-ranged solute-solvent interaction. The measured orientational relaxation dynamics show many clear and distinct deviations from simple hydrodynamic behavior. All ionic structures in all solvents exhibit multi-exponential relaxation dynamics that do not scale with the solute volume. For Lewis base solvents such as benzonitrile, dimethyl carbonate, and ethyl acetate, the observed dynamics strongly show the effect of solute-solvent complex formation. For the weak Lewis base solvent nitromethane, we see no evidence for solute-solvent complex formation, but still see strong deviation from the predictions of simple hydrodynamic theory. PMID:22239783

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

2012-01-01

2

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

3

Bimodal dielectric relaxation of electrolyte solutions in weakly polar solvents.  

PubMed

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. PMID:25554161

Yamaguchi, Tsuyoshi; Koda, Shinobu

2014-12-28

4

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

PubMed Central

Conspectus Reactions that convert carbon–hydrogen (C–H) bonds into carbon–carbon (C–C) or carbon–heteroatom (C–Y) bonds are attractive tools for organic chemists, potentially expediting the synthesis of target molecules through new disconnections in retrosynthetic analysis. Despite extensive inorganic and organometallic study of the insertion of homogeneous metal species into unactivated C–H bonds, practical applications of this technology in organic chemistry are still rare. Only in the past decade have metal-catalyzed C–H functionalization reactions become more widely utilized in organic synthesis. Research in the area of homogeneous transition metal–catalyzed C–H functionalization can be broadly grouped into two subfields. They reflect different approaches and goals and thus have different challenges and opportunities. One approach involves reactions of completely unfunctionalized aromatic and aliphatic hydrocarbons, which we refer to as “first functionalization.” Here the substrates are nonpolar and hydrophobic and thus interact very weakly with polar metal species. To overcome this weak affinity and drive metal-mediated C–H cleavage, chemists often use hydrocarbon substrates in large excess (for example, as solvent). Because highly reactive metal species are needed in first functionalization, controlling the chemoselectivity to avoid over-functionalization is often difficult. Additionally, because both substrates and products are comparatively low-value chemicals, developing cost-effective catalysts with exceptionally high turnover numbers that are competitive with alternatives (including heterogeneous catalysts) is challenging. Although an exciting field, first functionalization is beyond the scope of this Account. The second subfield of C–H functionalization involves substrates containing one or more pre-existing functional groups, termed “further functionalization.” One advantage of this approach is that the existing functional group (or groups) can be used to chelate the metal catalyst and position it for selective C–H cleavage. Precoordination can overcome the paraffin nature of C–H bonds by increasing the effective concentration of the substrate so that it needn't be used as solvent. From a synthetic perspective, it is desirable to use a functional group that is an intrinsic part of the substrate so that extra steps for installation and removal of an external directing group can be avoided. In this way, dramatic increases in molecular complexity can be accomplished in a single stroke through stereo- and site-selective introduction of a new functional group. Although reactivity is a major challenge (as with first functionalization), the philosophy in further functionalization differs—the major challenge is developing reactions that work with predictable selectivity in intricately functionalized contexts on commonly occurring structural motifs. In this Account, we focus on an emergent theme within the further functionalization literature: the use of commonly occurring functional groups to direct C–H cleavage through weak coordinations. We discuss our motivation for studying Pd-catalyzed C–H functionalization assisted by weakly coordinating functional groups and chronicle our endeavors to bring reactions of this type to fruition. Through this approach, we have developed reactions with a diverse range of substrates and coupling partners, with the broad scope likely stemming from higher reactivity of the less stable cyclopalladated intermediates held in place by weak coordinations. PMID:22166158

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

2011-01-01

5

Nanostructures of 2-heptadecylimidazole self-assembled through coordination or hydrogen bonding in polar organic solvents  

Microsoft Academic Search

Self-assembly properties of 2-heptadecylimidazole in organic solvents were investigated. It has been found that various nanostructures such as globular, ribbon, and sausage-like aggregates are spontaneously formed through hydrogen bonding and coordination with AgNO3 in polar organic solutions. Highly ordered lamellar structures were found on the solution cast film, as revealed by X-ray diffraction, which support the formation of ordered nanostructures

Haofei Gong; Minghua Liu

2003-01-01

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

Solvent wrapped metastable colloidal crystals: highly mutable colloidal assemblies sensitive to weak external disturbance.  

PubMed

Solvent wrapped "metastable" crystalline colloidal arrays (CCAs) have been prepared by supersaturation induced precipitation and self-assembly of monodisperse particles in polar/nonpolar organic solvents. These metastable CCAs possess ordered structures but with less stability comparing with traditionally fixed colloidal crystal systems. They are stabilized by the balance between long-range attraction and electrostatic repulsion of neighboring like-charged particles. Monitoring the reflection intensity during evaporation suggests that these crystals can exist for several hours at 90 °C and even longer at room temperature. Based on the evolution of particle volume fraction in whole suspension (?(SiO2)), crystal phase (?(crystal)), and liquid phase (?(liquid)), the formation of metastable CCAs can be understood as a microscopic phase separation process, where the homogeneous dispersion will separate into a "crystal phase" with orderly stacked particles and a "liquid phase" with randomly dispersed particles. Further calculation of the volume fraction of crystal phase (V(crystal)/V(total)) and the ratio of particles in crystal phase (f(crystal)) shows that with the increase of designed ?(SiO2), more particles precipitate to form colloidal crystals with larger sizes but the lattice spacing of the microcrystals remains constant. Unlike fixed or traditional responsive CCAs, these metastable CCAs can reversibly assemble and disassemble with great ease, because little energy is involved or required in this transformation. Therefore, they can sense weak external disturbances, including subtle motion and slight friction or shearing forces. PMID:24266836

Yang, Dongpeng; Ye, Siyun; Ge, Jianping

2013-12-11

9

Effects of solvent systems on two silver coordination complexes: From discrete structure to 2D sheet  

NASA Astrophysics Data System (ADS)

Two mixed-ligand silver(I) coordination complexes (CCs), [Ag4(mpyz)(npt)2·(H2O)2]n (1) and [Ag4(mpyz) (npt)2]n (2) were synthesized with reactions of methyl-pyrazine(mpyz) and 3-nitro-1,2-benzenedicarboxylic acid (H2npt) with silver nitrate in different solvent systems and were structurally characterized by single-crystal X-ray crystallography. Structural differences of CCs are due to the effects of solvent systems and the intricacy of the self-assembly process for these systems. For 1, the Ag4 unit which is like Y letter which stand upside and down and repeat to form a 1D-63-silver-ring which shares Ag1 and Ag2 only with npt ligands. The eight Ag ions of complex 2 are in a shape like the branches of a tree which repeat to form a 1D silver chain. Effects of solvents on the structures, as well as the intricacy of the self-assembly process were discussed. The photoluminescence, infrared spectroscopy (IR) and thermogravimetric analyses (TGA) behaviors of the compounds were also discussed.

Wang, Dan-Feng; Wang, Zhan-Hui; Lu, Bo-Wei; Chen, Shu-Fen; Zhang, Ting; Huang, Rong-Bin; Zheng, Lan-Sun

2014-02-01

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 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

11

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

12

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

PubMed

Retrieval-based face annotation is a promising paradigm of mining massive web facial images for automated face annotation. This paper addresses a critical problem of such paradigm, i.e., how to effectively perform annotation by exploiting the similar facial images and their weak labels which are often noisy and incomplete. In particular, we propose an effective Weak Label Regularized Local Coordinate Coding (WLRLCC) technique, which exploits the principle of local coordinate coding in learning sparse features, and employs the idea of graph-based weak label regularization to enhance the weak labels of the similar facial images. We present an efficient optimization algorithm to solve the WLRLCC task. We conduct extensive empirical studies on two large-scale web facial image databases: (i) a Western celebrity database with a total of $6,025$ persons and $714,454$ web facial images, and (ii)an Asian celebrity database with $1,200$ persons and $126,070$ web facial images. The encouraging results validate the efficacy of the proposed WLRLCC algorithm. To further improve the efficiency and scalability, we also propose a PCA-based approximation scheme and an offline approximation scheme (AWLRLCC), which generally maintains comparable results but significantly saves much time cost. Finally, we show that WLRLCC can also tackle two existing face annotation tasks with promising performance. PMID:23917420

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

2013-08-01

13

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=Ca-Cb-O-Cb-Ca=O backbone acts as a tridentate O donor, where the two carbonyl O atoms and the one ether O atom bond to Eu(3+). Given the structural rigidity of the tridentate coordination motif in [Eu(TODGA)3](3+) with six 5-membered chelate rings, the six Eu-Ca and six Eu-Cb interactions are readily resolved in the EXAFS (extended X-ray absorption fine structure) spectrum. The three charge balancing [BiCl4](-) anions are beyond the cationic [Eu(TODGA)3](3+) cluster in an outer sphere environment that is too distant to be detected by XAS. Despite their sizeable length and propensity for entanglement, the four n-octyl groups of each TODGA (for a total of twelve) do not perturb the Eu(3+) coordination environment over that seen from previously reported single-crystal structures of tripositive lanthanide (Ln(3+)) complexes with tetraalkyldiglycolamide ligands (of the same 1:3 metal-to-ligand ratio stoichiometry) but having shorter i-propyl and i-butyl groups. The present results set the foundation for understanding advanced solvent extraction processes for the separation of the minor, tripositive actinides (Am, Cm) from the Ln(3+) ions in terms of the local structure of Eu(3+) in a solid state coordination complex with TODGA. PMID:25310364

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

2015-01-14

14

ELSEVIER Chemical Physics 211 (1996) 47-71 Solvent reorganization energy of electron transfer in weakly  

E-print Network

ELSEVIER Chemical Physics 211 (1996) 47-71 Chemical Physics Solvent reorganization energy reaction. For the system considered, the dispersion and dipolar components of the energy gap vary is shown to be incapable of describing this phenomenon. 1. Introduction The solvent reorganization energy

Matyushov, Dmitry

1996-01-01

15

Pd(II)-Catalyzed C-H Functionalizations Directed by Distal Weakly Coordinating Functional Groups.  

PubMed

Ortho-C(sp(2))-H olefination and acetoxylation of broadly useful synthetic building blocks phenylacetyl Weinreb amides, esters, and ketones are developed without installing an additional directing group. The interplay between the distal weak coordination and the ligand-acceleration is crucial for these reactions to proceed under mild conditions. The tolerance of longer distance between the target C-H bonds and the directing functional groups also allows for the functionalizations of more distal C-H bonds in hydrocinnamoyl ketones, Weinreb amides, and biphenyl Weinreb amides. Mechanistically, the coordination of these carbonyl groups and the bisdentate amino acid ligand with Pd(II) centers provides further evidence for our early hypothesis that the carbonyl groups of the potassium carboxylate are responsible for the directed C-H activation of carboxylic acids. PMID:25768039

Li, Gang; Wan, Li; Zhang, Guofu; Leow, Dasheng; Spangler, Jillian; Yu, Jin-Quan

2015-04-01

16

Solvent-controlled three families of Zn(ii) coordination compounds: synthesis, crystal structure, solvent-induced structural transformation, supramolecular isomerism and photoluminescence.  

PubMed

This work reports the assembly, topological structure, supramolecular isomerism and luminescence of three solvent-controlled families of coordination compounds, [Zn(bpz)2(H2O)3·2Hpta] (), [Zn(bpz)(pta)]n (), [Zn(bpz)(tpa)(H2O)]n (), [Zn(bpz)(tpa)·4H2O]n (), and [Zn(bpz)(npa)·H2O]n ( and ) (bpz = 3,3',5,5'-tetramethyl-4,4'-bipyrazole, H2pta = phthalic acid, H2tpa = terephthalic acid, H2npa = 4-nitrophthalic acid). The six transition metal compounds reported in this study were definitely characterized by X-ray crystallography to reveal how networks with different topologies are constructed around the same four-connected metal centers. Compound is a 0D discrete molecule, in which Zn(ii) is in a trigonal bipyramidal coordination geometry, whereas the guest Hpta(-) as counteranion is hydrogen-bonded with the [Zn(bpz)2(H2O)3]. In compound , the Zn(ii) center is linked by two bpz and two pta; thus, a 4-connected dia network with the point symbol {6(6)} is formed. In , the Zn(ii) center is six-coordinated, but in fact it is also a 4-connected node in the whole network due to the terminal aqua ligand and bidentate chelating carboxylate group thus, the resultant network has a 4-connected cds topology with the point symbol {6(5)·8}. Compound exhibits a chiral two-fold interpenetrated 4-connected qtz network with the point symbol {6(4)·8(2)}. Compounds and are a pair of genuine supramolecular isomers with identical 4-connected dia topology. The three families of compounds, namely, /, /, and /, are structurally controlled by the solvent systems H2O/CH3OH-H2O, H2O/DMF-CH3OH, and CH3OH-H2O/CH3CN-H2O, respectively. Except for the discrete molecule , the other five compounds have the same 4-connected coordination networks, but with different topologies ranging from dia (, , ), cds () to qtz (), suggesting the important influences that the linkage orientations of the ligand and different geometries of the 4-connected node exert in self-assembly. Interestingly, discrete can be irreversibly transformed from a 0D discrete molecule to an infinite 3D structure () by heating it in CH3OH-H2O solvent, indicating a solvent-induced structural transformation. In addition, results about thermal stabilities and photoluminescence spectra are also discussed in detail. PMID:25728056

Han, Lu-Lu; Hu, Tuo-Ping; Mei, Kai; Guo, Zhi-Min; Yin, Chen; Wang, Ya-Xin; Zheng, Jun; Wang, Xing-Po; Sun, Di

2015-03-17

17

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

18

Solvent and nuclear dynamics in ultrafast intermolecular electron transfer in a diffusionless, weakly polar system  

NASA Astrophysics Data System (ADS)

Femtosecond intermolecular electron (ET) transfer dynamics were studied by time-resolved fluorescence up-conversion technique in contact systems of oxazine dyes in electron-donating solvents. Clearly non-exponential ET time dependence was observed in aniline and explained by the effects of both solvent reorientation and nuclear motion of the reactants. Single exponential processes were measured for nile blue (?160 fs) and oxazine 1 (?280 fs) in N,N-dimethylaniline. The rate of ET is explained to be limited only by ultrafast nuclear relaxation.

Yartsev, Arkadiy; Nagasawa, Yutaka; Douhal, Abderrazzak; Yoshihara, Keitaro

1993-05-01

19

WBC-ALC: A Weak Blocking Coordinated Application-Level Checkpointing for MPI Programs  

NASA Astrophysics Data System (ADS)

As supercomputers increase in size, the mean time between failures (MTBF) of a system becomes shorter, and the reliability problem of supercomputers becomes more and more serious. MPI is currently the de facto standard used to build high-performance applications, and researches on the fault tolerance methods of MPI are always hot topics. However, due to the characteristics of MPI programs, most current checkpointing methods for MPI programs need to modify the MPI library (even operating system), or implement a complicated protocol by logging lots of messages. In this paper, we carry forward the idea of Application-Level Checkpointing (ALC). Based on the general fact that programmers are familiar with the communication characteristics of applications, we have developed BC-ALC, a new portable blocking coordinated ALC for MPI programs. BC-ALC neither modifies the MPI library (even operating system) nor logs any message. It implements coordination only by the Barrier operations instead of any complicated protocol. Furthermore, in order to reduce the cost of fault-tolerance, we reduce the synchronization range of the barrier, and design WBC-ALC, a weak blocking coordinated ALC utilizing group synchronization instead of global synchronization based on the communication relationship between processes. We also propose a fault-tolerance framework developed on top of WBC-ALC and discuss an implementation of it. Experimental results on NPB3.3-MPI benchmarks validate BC-ALC and WBC-ALC, and show that compared with BC-ALC, the average coordination time and the average backup time of a single checkpoint in WBC-ALC are reduced by 44.5% and 5.7% respectively.

Xu, Xinhai; Yang, Xuejun; Lin, Yufei

20

Symmetry breaking in the relaxed S(1) excited state of bianthryl derivatives in weakly polar solvents.  

PubMed

The flash-photolysis time-resolved microwave conductivity technique (FP-TRMC) has been used to investigate the nature of the relaxed S(1) state of 9,9'-bianthryl (AA), 10-cyano-9,9'-bianthryl (CAA), and 10,10'-dicyano-9,9'-bianthryl (CAAC). Changes in both the real, Deltaepsilon' (dielectric constant), and imaginary, Deltaepsilon' ' (dielectric loss), components of the complex permittivity have been measured. The dielectric loss transients conclusively demonstrate the dipolar nature of S(1) for all three compounds in the pseudopolar solvents benzene and 1,4-dioxane, and even in the nonpolar solvents n-hexane and cyclohexane. The required symmetry breaking is considered to result from density and structural fluctuations in the solvent environment. The dipole relaxation times for AA (CAAC) are ca. 2 ps for the alkanes and 7.9 (5.3) and 14 (14) ps for benzene and dioxane, respectively. The time scale of dipole relaxation for the symmetrical compounds is much shorter than that for rotational diffusion and is attributed to intramolecular, flip-flop dipole reversal via a neutral excitonic state. The dipole moment of the transient dipolar state is estimated to be ca. 8 D, that is much lower than the value of ca. 20 D determined from the solvatochromic shifts in the fluorescence in intermediate to highly polar solvents which corresponds to close to complete charge separation. For the asymmetric compound, CAA, a dipole moment close to 20 D is found in all solvents, including n-hexane. Dipole relaxation in this case occurs on a time scale of several hundred picoseconds and is controlled mainly by diffusional rotation of the molecules. The mechanism and kinetics of formation of the dipolar excited states are discussed in the light of these results. PMID:11457397

Piet, J J; Schuddeboom, W; Wegewijs, B R; Grozema, F C; Warman, J M

2001-06-01

21

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

22

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

23

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

NASA Astrophysics Data System (ADS)

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.

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

2014-08-01

24

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

PubMed Central

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

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

2015-01-01

25

Calorimetric study on coordination of tridentate imidazolyl calix[6]arene ligands to zinc ion in organic solvents.  

PubMed

Complexation of three kinds of tris(imidazolyl)calix[6]arenes containing alternate p-substituents (Calix-tBu, R(1) = R(2) = tert-butyl; Calix-NH(2), R(1) = tert-butyl, R(2) = NH(2); Calix-NO(2), R(1) = tert-butyl, R(2) = NO(2)) with Zn(ClO(4))(2)(H(2)O)(6) in acetonitrile, methanol, and THF was investigated via isothermal titration calorimetry (ITC). For the coordination of these calixarene ligands to Zn(II) in acetonitrile, typical one-phase exothermic titration curves were obtained, indicating the formation of 1:1 ligand-Zn(II) complexes accompanied by large conformational changes of the ligands. In contrast, the complexation in methanol was endothermic and dominated by favorable entropy changes. The entropy gains were achieved by extensive desolvation from both Zn(II) and the ligands. ITC measurements suggest a 2:1 ligand-Zn(II) complex formation in THF in the presence of excess ligands (Calix-NH(2) and Calix-NO(2)). The 2:1 complexes were converted to 1:1 complexes upon further addition of Zn(ClO(4))(2)(H(2)O)(6). The results indicate the important role of a coordinating solvent (acetonitrile) for direct formation of the 1:1 complexes under the conditions of excess ligand. Complexation of a ditopic ligand (Calix-Tri) with three triazole moieties on the wider rim was also studied via ITC. The first coordination of the imidazole moieties to Zn(II) was an exothermic process. This was followed by the entropically favorable coordination of the triazole moieties to the divalent cation. We have also investigated exchange of the fourth ligand (H(2)O) of the Zn(II) complex of Calix-NH(2) with butylamine, heptylamine, acetonitrile, and acetamide in a noncompetitive solvent, THF. The ?H(0) tended to decrease upon increasing the electron-pair-donating ability of the guest ligand, whereas it was also affected by an entropic term due to restricted rotation of the guest ligand inside the calixarene cavity. PMID:21648400

Kano, Koji; Kondo, Masataka; Inoue, Haruka; Kitagishi, Hiroaki; Colasson, Benoit; Reinaud, Olivia

2011-07-01

26

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

27

Insertion of functional groups into a Nd3+ metal-organic framework via single-crystal-to-single-crystal coordinating solvent exchange.  

PubMed

Single-crystal-to-single-crystal (SCSC) transformations represent some of the most fascinating phenomena in chemistry. They are not only intriguing from a basic science point of view but also provide a means to modify or tune the properties of the materials via the postsynthetic introduction of suitable guest molecules or organic functional groups into their structures. Here, we describe UCY-2, a new flexible Nd(3+) metal-organic framework (MOF), which exhibits a unique capability to undergo a plethora of SCSC transformations with some of them being very uncommon. These structural alterations involve the replacement of coordinating solvent molecules of UCY-2 by terminally ligating solvents and organic ligands with multiple functional groups including -OH, -SH, -NH-, and -NH(2) or their combinations, chelating ligands, anions, and two different organic compounds. The SCSC coordinating solvent exchange is thus demonstrated as a powerful method for the functionalization of MOFs. PMID:22591070

Manos, Manolis J; Kyprianidou, Eleni J; Papaefstathiou, Giannis S; Tasiopoulos, Anastasios J

2012-06-01

28

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.

David Stern

29

Continuum Hartree-Fock-Bogoliubov theory for weakly bound deformed nuclei using the coordinate-space Green's function method  

SciTech Connect

We formulate a new scheme of the Hartree-Fock-Bogoliubov mean-field theory applicable to weakly bound and pair-correlated deformed nuclei using the coordinate-space Green's function technique. On the basis of a coupled-channel representation of the quasiparticle wave function expanded in terms of the partial waves, we impose the correct boundary condition of the asymptotically out-going waves on the continuum quasiparticle states. We perform numerical analysis for {sup 38}Mg to illustrate properties of the continuum quasiparticle states and the pair correlation in deformed nuclei near the neutron drip line.

Oba, Hiroshi [Graduate School of Science and Technology, Niigata University, Niigata 950-2181 (Japan); Matsuo, Masayuki [Department of Physics, Faculty of Science, Niigata University, Niigata 950-2181 (Japan)

2009-08-15

30

The effect of coordinated solvent ligands on the solid-state structures of compounds involving uranyl nitrate and Schiff bases  

Microsoft Academic Search

A range of solvent adducts of uranyl complexes of the Schiff base ligands salen (salen?N,N?-ethylenebis(salicylidenimine)) and salpn (?N,N?-propylenebis(salicylidenimine)) have revealed similar morphologies about the uranium centre. Subtle differences in hydrogen bonding arrays, types of solvents and conformation of the Schiff base ligands result in vastly different crystal packing motifs.

David J Evans; Peter C Junk; Matthew K Smith

2002-01-01

31

[Cu(I)(bpp)]BF4: the first extended coordination network prepared solvothermally in an ionic liquid solvent  

E-print Network

a solvothermal route. In the past few years, room temperature ionic liquids (RTILs), especially those based dimensional framework via weak inter-chain interactions of copper pairs. The Cu(I)­Cu(I) weak interactions is the only structure found similar to 1, which was prepared by slow diffusion using silver per- chlorate

Li, Jing

32

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.

33

Luminescence properties and water coordination of Eu3+ in the binary solvent mixture water/1-butyl-3-methylimidazolium chloride.  

PubMed

The effect of relative water content on the luminescence properties and speciation of Eu3+ ions in solutions of EuCl3 in the binary solvent mixture water/[BMI]Cl is presented, where [BMI]Cl is the ionic liquid (IL) 1-butyl-3-methylimidazolium chloride. Using luminescence techniques, the binding properties of water to Eu3+ are determined for samples with mole ratios of water-to-IL ranging from 0 to 5. Very little water binds to Eu3+ at mole ratios of water-to-IL less than 1, above which binding increases rapidly with increasing water concentration. It is shown that only certain hydration numbers for Eu3+ complexes are stable in the water/IL solutions. The data presented suggest that the Eu3+ species present are [EuClx]3-x, [EuCly(H2O)3-4]3-y, [EuClz(H2O)6]3-z, and [Eu(H2O)8-9]3+ (where x > y > z). Comparison of the positions of the 5D0<--7F0 transitions of the Eu3+ complexes in IL solution with those of model crystal systems provides insight into the extent of Cl- complexation. This study suggests that [BMI]Cl is a promising medium for luminescent lanthanide (Ln) compounds due to the low-energy phonon environment of the [LnClx]3-x complex and to the fact that moderate water contamination does not result in direct binding of water to Ln3+, which would result in luminescence quenching. PMID:17655287

Samikkanu, Senthamizh; Mellem, Kevin; Berry, Mary; May, P Stanley

2007-08-20

34

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

PubMed

A series of eight new Hg(ii) complexes based on the L(4-X) ligands, where L is (E) -4-halo-N-(pyridin-4-ylmethylene)aniline, were synthesized and characterized and their supramolecular crystal structures were studied by different geometrical and theoretical methods. Our study reveals the role of weak intermolecular interactions involving halogens, such as C-HX hydrogen bonds (in the cases of , , , , and ) and C-XX'-M halogen bonds (in the cases of and ), in the structural changes of supramolecular assemblies of coordination compounds. Complexes were also synthesized by sonochemical irradiation and the morphology of the prepared complexes was investigated using FE-SEM. The BFDH analysis helps us to compare the predicted morphology to that obtained under ultrasonication. This study may provide further insight into discovering the role of weak intermolecular interactions in the context of metallosupramolecular assembly. PMID:25710629

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

2015-03-10

35

Solvent or temperature induced diverse coordination polymers of silver(I) sulfate and bipyrazole systems: syntheses, crystal structures, luminescence, and sorption properties.  

PubMed

Three new coordination polymers, [Ag4(H2bpz)4(SO4)2]·H2O (1), [Ag2(H2bpz)2(SO4)]·3H2O (2), and [Ag3(H2bpz)4](SO4)2/3(OH)5/3·4H2O (3) have been solvothermally synthesized with Ag2SO4 and flexible ligand 3,3',5,5'-tetramethyl-4,4'-bipyrazole (H2bpz) in different solvents and temperatures. Complex 1 is a 2-fold interpenetrated three-dimensional (3D) framework with an uncommon (3,5)-connected hms topology. Complex 2 is a structural isomer of 1 and shows a three-connected 2D ths net consisting of interesting 3-fold and 2-fold heterochiral helical chains. Complex 3 discloses a grid layer structure, containing heterochiral helical chains and an unusual meso-helix. More interestingly, three sets of layers in 3 stack in different directions, affording an unprecedented 2D + 2D + 2D ? 3D polycatenating cationic framework with 1D + 3D porous systems. In 1-3, H2bpz exhibit exobidentate bridging fashions with wide-ranged interpyrazole tilting angles and changeable coordination configurations, such as cis and trans fashions in 1 and 3 and uniform trans fashion in 2. These lead to the isomeric [Ag(H2bpz)]n arrays of wavelike and helical chains in 1 and 2, respectively. Complexes 1-3 display solid-state photoluminescence stemming from the ligand-centered fluorescent emissions of H2bpz. Because of the highly polar framework, 3 shows excellent adsorption selectivity for CO2 over N2. PMID:24295278

Du, Li-Yun; Shi, Wen-Juan; Hou, Lei; Wang, Yao-Yu; Shi, Qi-Zhen; Zhu, Zhonghua

2013-12-16

36

Synthesis of the salts of weakly coordination stibate ions & Students' perceptions of two- and three-dimensional animations depicting an oxidation-reduction reaction  

NASA Astrophysics Data System (ADS)

SYTHESIS OF SALTS OF WEAKLY COORDINATING STIBATE IONS. Weakly coordinating anions have many important applications including olefin polymerization co-catalysis. In an attempt to make tristibic acid, distibic acid and tetrastibic acid were made. Cesium, barium, nickel(II), and diethylammonium salts of tetrastibic acid were also synthesized. Tetrastibic acid and the ammonium salts were concluded to be stable. Elemental analyses showed that neither tristibic acid nor tristibic acid were stable under the reaction conditions employed. STUDENTS' PERCEPTIONS OF TWO- AND THREE-DIMENSIONAL ANIMATIONS DEPICTING AN OXIDATION-REDUCATION REACTION. Electrochemistry is a difficult subject for many students to comprehend. In order to improve teaching in this area of chemistry, semi-structured clinical interviews on second-semester introductory chemistry students were conducted in which students' were asked to explain the particulate behavior of the chemicals in an oxidation-reduction reaction. The interviews included questions after students viewed the chemical demonstration and two computer animations depicting the particulate nature of the same chemical reaction. Misinterpretations of the two animations were identified and described in detail. The simpler 2-D animation was beneficial in helping students understand the oxidation-reduction reaction and write the balanced chemical equation. However, the 3-D animation did not appear to be detrimental to student understanding. Suggestions, taken from the students' comments in the interviews, for improving the animations and for teaching electrochemistry were discussed.

Rosenthal, Deborah Renee

2011-12-01

37

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

38

Na4 IrO4 : Square-Planar Coordination of a Transition Metal in d(5) Configuration due to Weak On-Site Coulomb Interactions.  

PubMed

Local environments and valence electron counts primarily determine the electronic states and physical properties of transition-metal complexes. For example, square-planar coordination geometries found in transition-metal oxometalates such as cuprates are usually associated with the d(8) ?or d(9) ?electron configuration. In this work, we address an unusual square-planar single oxoanionic [IrO4 ](4-) ?species, as observed in Na4 IrO4 in which Ir(IV) has a d(5) ?configuration, and characterize the chemical bonding through experiments and by ab?initio calculations. We find that the Ir(IV) ?center in ground-state Na4 IrO4 has square-planar coordination geometry because of the weak Coulomb repulsion of the Ir-5d electrons. In contrast, in its 3d counterpart Na4 CoO4 , the Co(IV) center is tetrahedrally coordinated because of strong electron correlation. Na4 IrO4 may thus serve as a simple yet important example to study the ramifications of Hubbard-type Coulomb interactions on local geometries. PMID:25772377

Kanungo, Sudipta; Yan, Binghai; Merz, Patrick; Felser, Claudia; Jansen, Martin

2015-04-27

39

Conversion of tetrahedral to octahedral structures upon solvent coordination: studies on the M[(OPPh2)(SePPh2)N]2 (M = Co, Ni) and [Ni{(OPPh2)(EPPh2)N}2(dmf)2] (E = S, Se) complexes.  

PubMed

The synthesis of the M[(OPPh(2))(SePPh(2))N](2), M = Co (1), Ni (2) complexes was accomplished by metathetical reactions between the corresponding M(II) salts and the deprotonated form of the dichalcogenated imidodiphosphinato ligand [(OPPh(2))(SePPh(2))N](-). X-Ray crystallography revealed a pseudo-tetrahedral MO(2)Se(2) coordination sphere, owing to the asymmetric (O,Se) nature of the chelating ligand. Slow diffusion of the coordinating solvent dimethylformamide into dichloromethane solutions of Ni[(OPPh(2))(SPPh(2))N](2) or 2, afforded the pseudo-octahedral trans-[Ni{(OPPh(2))(EPPh(2))N}(2)(dmf)(2)], E = S (3), Se (4) complexes, respectively. UV-vis spectra provided evidence that, in solution, complexes 3 and 4 revert to the corresponding pseudo-tetrahedral complexes, most likely due to the removal of the dmf molecules from the coordination sphere. The IR spectra of all complexes reflect the structural features observed by X-ray crystallography. The magnetic properties of the S = 3/2 complex 1, as well as the S = 1 complexes 2, 3 and 4, were extensively studied, and the magnitude of their g and zero-field splitting D parameters was estimated. The reported structures establish a structural transformation of tetrahedral to octahedral geometry of Ni(II) complexes bearing asymmetric imidodiphosphinate ligands, upon recrystallization from coordinating solvents. The structural correlations between the Ni(II) coordination spheres are aided by DFT and ab initio multi-configuration MCSCF calculations, which investigate the corresponding interconversion pathways. In addition, the calculations provide descriptions of the bonding interactions in the octahedral Ni(II) complexes, as well as predictions of their D values. PMID:21076739

Ferentinos, Eleftherios; Maganas, Dimitrios; Raptopoulou, Catherine P; Terzis, Aris; Psycharis, Vassilis; Robertson, Neil; Kyritsis, Panayotis

2011-01-01

40

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

NASA Astrophysics Data System (ADS)

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

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

2015-03-01

41

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

42

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

PubMed

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

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

2015-03-01

43

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

1977-01-01

44

Eutectic mixture of choline chloride\\/urea as a green solvent in synthesis of a coordination polymer: [Zn(O 3PCH 2CO 2)] · NH 4  

Microsoft Academic Search

A eutectic mixture of choline chloride\\/urea is liquid at ambient temperature and is used as a non-volatile reaction medium for the synthesis and crystallization of a novel coordination polymer, Zn(O3PCH2CO2)·NH4, in which structure-directing ammonium ions are generated in situ from the partial decomposition of urea.

Ju-Hsiou Liao; Pei-Chi Wu; Yi-Hsuan Bai

2005-01-01

45

The solvent-fixed coordinate system applied to two-phase diffusion coatings resulting from a constant surface flux of solute  

Microsoft Academic Search

The explicit finite difference form of the diffusion equation has been used to describe a two-phase binary diffusion problem which includes a constant surface flux boundary condition, a concentration-dependent diffusion coefficient, and dimensional change due to both additions of material and nonideal solution behavior. The xigamma coordinate system, containing an equal number of mols of the substrate component per increment,

Donald L. Creighton; Robert L. Benedetti

1977-01-01

46

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

47

The solvent-fixed coordinate system applied to two-phase diffusion coatings resulting from a constant surface flux of solute  

Microsoft Academic Search

The explicit finite difference form of the diffusion equation has been used to describe a two-phase binary diffusion problem\\u000a which includes a constant surface flux boundary condition, a concentration-dependent diffusion coefficient, and dimensional\\u000a change due to both additions of material and nonideal solution behavior. The ?? coordinate system, containing an equal number of mols of the substrate component per increment,

Donald L. Creighton; Robert L. Benedetti

1977-01-01

48

An Interconverting Family of Coordination Cages and a meso-Helicate; Effects of Temperature, Concentration, and Solvent on the Product Distribution of a Self-Assembly Process.  

PubMed

The self-assembly between a water-soluble bis-bidentate ligand L(18w) and Co(II) salts in water affords three high-spin Co(II) products: a dinuclear meso-helicate [Co2(L(18w))3]X4; a tetrahedral cage [Co4(L(18w))6]X8; and a dodecanuclear truncated-tetrahedral cage [Co12(L(18w))18]X24 (X = BF4 or ClO4). All three products were crystallized under different conditions and structurally characterized. In [Co2(L(18w))3]X4 all three bridging ligands span a pair of metal ions; in the two larger products, there is a metal ion at each vertex of the Co4 or Co12 polyhedral cage array with a bridging ligand spanning a pair of metal ions along every edge. All three structural types are known: what is unusual here is the presence of all three from the same reaction. The assemblies Co2, Co4, and Co12 are in slow equilibrium (hours/days) in aqueous solution, and this can be conveniently monitored by (1)H NMR spectroscopy because (i) the paramagnetism of Co(II) disperses the signals over a range of ca. 200 ppm and (ii) the different symmetries of the three species give characteristically different numbers of independent (1)H NMR signals, which makes identification easy. From temperature- and concentration-dependent (1)H NMR studies it is clear that increasing temperature and increasing dilution favors fragmentation to give a larger proportion of the smaller assemblies for entropic reasons. High concentrations and low temperature favor the larger assembly despite the unfavorable entropic and electrostatic factors associated with its formation. We suggest that this arises from the hydrophobic effect: reorganization of several smaller complexes into one larger one results in a smaller proportion of the hydrophobic ligand surface being exposed to water, with a larger proportion of the ligand surface protected in the interior of the assembly. In agreement with this, (1)H NMR spectra in a nonaqueous solvent (MeNO2) show formation of only [Co2(L(18w))3]X4 because the driving force for reorganization into larger assemblies is now absent. Thus, we can identify the contributions of temperature, concentration, and solvent on the result of the metal/ligand self-assembly process and have determined the speciation behavior of the Co2/Co4/Co12 system in aqueous solution. PMID:25700155

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

2015-03-16

49

Solvent substitution  

SciTech Connect

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

Not Available

1990-01-01

50

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,...

51

Organic solvents in the workplace  

SciTech Connect

On March 31, 1987, the National Institute for Occupational Safety and health (NIOSH) released Current Intelligence Bulletin number48: Organic Solvent Neurotoxicity. This is another in a series of NIOSH publications on specific chemical substances, physical agents, or safety hazards found in the workplace. The document is now available to the public. Acute exposure to organic solvents can impair manual dexterity, response speed, coordination, or body balance. Epidemiologic studies of workers chronically exposed to organic solvents have demonstrated reduced function of peripheral nerves and increases in the rates of adverse neurobehavioral effects. Results of studies involving the chronic exposure of animals to a limited number of organic solvents support the observations of peripheral nervous system dysfunction and neurobehavioral effects in humans.

Not Available

1987-06-19

52

Fluoro- and Perfluoralkylsulfonylpentafluoroanilides: Synthesis and Characterization of NH Acids for Weakly Coordinating Anions and Their Gas-Phase and Solution Acidities.  

PubMed

Fluoro- and perfluoralkylsulfonyl pentafluoroanilides [HN(C6 F5 )(SO2 X); X=F, CF3 , C4 F9 , C8 F17 ] are a class of imides with two different strongly electron-withdrawing substituents attached to a nitrogen atom. They are NH acids, the unsymmetrical hybrids of the well-known symmetrical bissulfonylimides and bispentafluorophenylamine. The syntheses, the structures of these perfluoroanilides, their solvates, and some selected lithium salts give rise to a structural variety beyond the symmetrical parent compounds. The acidities of representative subsets of these novel NH acids have been investigated experimentally and quantum-chemically and their gas-phase acidities (GAs) are reported, as well as the pKa values of these compounds in acetonitrile (MeCN) and DMSO solution. In quantum chemical investigations with the vertical and relaxed COSMO cluster-continuum models (vCCC/rCCC), the unusual situation is encountered that the DMSO-solvated acid Me2 SO-H-N(SO2 CF3 )2 , optimized in the gas phase (vCCC model), dissociates to Me2 SO-H(+) -N(SO2 CF3 )2 (-) during structural relaxation and full optimization with the solvation model turned on (rCCC model). This proton transfer underlines the extremely high acidity of HN(SO2 CF3 )2 . The importance of this effect is studied computationally in DMSO and MeCN solution. Usually this effect is less pronounced in MeCN and is of higher importance in the more basic solvent DMSO. Nevertheless, the neglect of the structural relaxation upon solvation causes typical changes in the computational pKa values of 1 to 4 orders of magnitude (4-20?kJ?mol(-1) ). The results provide evidence that the published experimental DMSO pKa value of HN(SO2 CF3 )2 should rather be interpreted as the pKa of a Me2 SO-H(+) -N(SO2 CF3 )2 (-) contact ion pair. PMID:25727401

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

2015-04-01

53

Can weak interactions modify the binding properties of a strong nitrogen donor? Unusual N-coordination of a phosphoranylidene-substituted pyrazolone unit towards palladium(II) centres: an experimental and theoretical study.  

PubMed

Selective N(2)-binding of 3-methyl-1-phenyl-4-(triphenylphosphoranylidene)-2-pyrazolin-5-one (L) has been found in two palladium(II) complexes, [PdCl(2)L(2)](2) and [Pd(o-C(6)H(4)CH(2)NMe(2))Cl](3). X-Ray diffraction studies show that the pyrazole rings lie almost perpendicular to the coordination plane. In both complexes the metal atom is located out of the plane defined by the pyrazole ring(s)(dihedral angle between the plane and the Pd-N vector approximately 30 degrees). To investigate the origin of this distortion, a theoretical study was carried out on a simplified model of complex , where a single pyrazolone ligand was replaced by NH(3). From this study it could be inferred that the out-of-plane distortion mainly involves weak, electrostatic interactions between a chlorine atom and an ortho-aromatic H atom of the N(1)-linked phenyl group, as well as between the other chlorine atom and an ortho-aromatic H atom of the PPh(3) group. PMID:16172639

Mota, Antonio J; Dedieu, Alain; Kuhn, Pierre; Matt, Dominique; Welter, Richard; Neuburger, Markus

2005-10-01

54

Dynamics of solvent response in methanol-chloroform binary solvent mixture: a case of synergistic solvation.  

PubMed

Steady-state absorption, emission, and femtosecond transient absorption spectroscopies were used to ascertain the static and dynamic nature of the solvent response of methanol-chloroform binary solvent mixtures of different stoichiometric ratios using 4-(dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran (DCM) as the probe molecule. The appearance of synergistic solvation behavior in the steady-state absorption measurements can be explained in terms of solvent-solvent interactions through an extended hydrogen-bonding network. The disappearance of such synergistic behavior in the excited state of the DCM dye was recently proposed by us to be due to the weak nature of the intermolecular interactions present in binary solvent mixtures ( J. Phys. Chem. B 2012 , 116 , 1345 ). It was anticipated and subsequently confirmed by the dynamics of the solvent response that the disruption of the weak interactive solvent network is the main reason for the absence of the synergism in the excited state. As expected, we observed the slowest dynamics for the mixture with XMeOH = 0.45, with an average solvation time of 12.03 ps, which is much higher than the values for the pure bulk counterparts (??s?Methanol = 4.32 ps and ??s?Chloroform = 1.32 ps). The unprecedented slowing of solvation for DCM is probably due to the rigid interactive methanol-chloroform solvent system in the first solvation shell, followed by solvent rearrangements around the solute dipole. Overall interactions present within the methanol-chloroform binary solvent mixture furnish clear evidence of solvent association through weak hydrogen bonding. PMID:25607924

Gupta, Shradhey; Rafiq, Shahnawaz; Sen, Pratik

2015-02-19

55

Synthesis of room-temperature ionic liquids with the weakly coordinating [Al(ORF)4]- anion (RF=C(H)(CF3)2) and the determination of their principal physical properties.  

PubMed

A large series of ionic liquids (ILs) based on the weakly coordinating alkoxyaluminate [Al(hfip)(4)](-) (hfip: hexafluoroisopropoxy) with classical as well as functionalized cations were prepared, and their principal physical properties determined. Melting points are between 0 ([C(4)MMIM][Al(hfip)(4)]) and 69 °C ([C(3)MPip][Al(hfip)(4)]); three qualify as room-temperature ILs (RTILs). Crystal structures for six ILs were determined; their structural parameters and anion-cation contacts are compared here with known ILs, with a special focus on their influence on physical properties. Moreover, the biodegradability of the compounds was investigated by using the closed-bottle and the manometric respirometry test. Temperature-dependent viscosities and conductivities were measured between 0 and 80 °C, and described by either the Vogel-Fulcher-Tammann (VFT) or the Arrhenius equations. Moreover, conductivities and viscosities were investigated in the context of the molecular volume, V(m). Physical property-V(m) correlations were carried out for various temperatures, and the temperature dependence of the molecular volume was analyzed by using crystal structure data and DFT calculations. The IL ionicity was investigated by Walden plots; according to this analysis, [Al(hfip)(4)](-) ILs may be classified as "very good to good ILs"; while [C(2)MIM][Al(hfip)(4)] is a better IL than [C(2)MIM][NTf(2)]. The dielectric constants of ten [Al(hfip)(4)](-) ILs were determined, and are unexpectedly high (?(r)=11.5 to 16.8). This could be rationalized by considering additional calculated dipole moments of the structures frozen in the solid state by DFT. The determination of hydrogen gas solubility in [Al(hfip)(4)](-) RTILs by high-pressure NMR spectroscopy revealed very high hydrogen solubilities at 25 °C and 1 atm. These results indicate the significant potential of this class of ILs in manifold applications. PMID:20886467

Bulut, Safak; Klose, Petra; Huang, Mian-Mian; Weingärtner, Hermann; Dyson, Paul J; Laurenczy, Gábor; Friedrich, Christian; Menz, Jakob; Kümmerer, Klaus; Krossing, Ingo

2010-11-22

56

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

57

Solvent wash solution  

DOEpatents

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

Neace, James C. (Blackville, SC)

1986-01-01

58

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

59

Solvent recovery targeting  

SciTech Connect

One of the environmental challenges faced by the pharmaceutical and specialty chemical industries is the widespread use of organic solvents. With a solvent-based chemistry, the solvent necessarily has to be separated from the product. Chemical species in waste-solvent streams typically form multicomponent azeotropic mixtures, and this often complicates separation and, hence, recovery of solvents. A design approach is presented whereby process modifications proposed by the engineer to reduce the formation of waste-solvent streams can be evaluated systematically. This approach, called solvent recovery targeting, exploits a recently developed algorithm for elucidating the separation alternatives achievable when applying batch distillation to homogeneous multicomponent mixtures. The approach places the composition of the waste-solvent mixture correctly in the relevant residue curve map and computes the maximum amount of pure material that can be recovered via batch distillation. Solvent recovery targeting is applied to two case studies derived from real industrial processes.

Ahmad, B.S.; Barton, P.I. [Massachusetts Inst. of Tech., Cambridge, MA (United States)] [Massachusetts Inst. of Tech., Cambridge, MA (United States)

1999-02-01

60

Polar Coordinates  

NSDL National Science Digital Library

This activity allows the user to explore the polar coordinate system. The applet is similar to GraphIt, but instead allows users to explore the representation of a function in the polar coordinate system.

61

coordinate plane  

NSDL National Science Digital Library

Become familiar with the coordinate plane. Learn the quadrants and how to graph points and read points on a coordinate plane. You are required to do the assignment and take the quiz. The other resources are to help prepare you for the quiz and book assignment. This is a quick review of the lesson.The Coordinate Plane This is a game to practice plotting and reading points.coordinates game *Assignment: Watch Powerpoint 3.3 and fill in your ...

olsen

2010-10-07

62

Structural and dynamical properties of Li+-dibenzo-18-crown-6(DB18C6) complex in pure solvents and at the aqueous-organic interface.  

PubMed

Microstructure of dibenzo-18-crown-6 (DB18C6) and DB18C6/Li(+) complex in different solvents (water, methanol, chloroform, and nitrobenzene) have been analyzed using radial distribution function (RDF), coordination number (CN), and orientation profiles, in order to identify the role of solvents on complexation of DB18C6 with Li(+), using molecular dynamics (MD) simulations. In contrast to aqueous solution of LiCl, no clear solvation pattern is found around Li(+) in the presence of DB18C6. The effect of DB18C6 has been visualized in terms of reduction in peak height and shift in peak positions of g(Li-Ow). The appearance of damped oscillations in velocity autocorrelation function (VACF) of complexed Li(+) described the high frequency motion to a "rattling" of the ion in the cage of DB18C6. The solvent-complex interaction is found to be higher for water and methanol due to hydrogen bond (HB) interactions with DB18C6. However, the stability of DB18C6/Li(+) complex is found to be almost similar for each solvent due to weak complex-solvent interactions. Further, Li(+) complex of DB18C6 at the liquid/liquid interface of two immiscible solvents confirm the high interfacial activity of DB18C6 and DB18C6/Li(+) complex. The complexed Li(+) shows higher affinity for water than organic solvents; still they remain at the interface rather than migrating toward water due to higher surface tension of water as compared to organic solvents. These simulation results shed light on the role of counter-ions and spatial orientation of species in pure and hybrid solvents in the complexation of DB18C6 with Li(+). PMID:25129659

Sahu, Pooja; Ali, Sk M; Singh, Jayant K

2014-09-01

63

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

Microsoft Academic Search

We investigate the role played by the coordination state of pre-existing water wires during the dissociation of moderately strong acids by means of first-principles molecular dynamics calculations. By preparing 2,4,6-tricyanophenol (calc. pKa~0.5) in two different initial states, we are able to observe sequential as well as concerted trajectories of dissociation: On one hand, equilibrium dissociation takes place on a ~50

Patrick Maurer; Vibin Thomas; Radu Iftimie

2011-01-01

64

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

NASA Astrophysics Data System (ADS)

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

Maurer, Patrick; Thomas, Vibin; Iftimie, Radu

2011-03-01

65

Solvent recycle/recovery  

SciTech Connect

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

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

1990-09-01

66

Astronomical Coordinates  

NSDL National Science Digital Library

The celestial coordinate system is a projection of earth's coordinate system into the celestial sphere. Being just like Earth's system it contains an "equator", lines of "latitude" and "longitude", and even poles. (Though we don't use the same words for it.) One suggestion one might have would be to just extend the Earth's latitude, longitude, and equator out into the night sky, but the Earth is constantly spinning. For the Celestial coordinates, we have to pick some fixed reference to go by.

David Joiner

67

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: atmospheric batch distillation, vacuum heat-pump distillation, and a low-emission vapor degreaser with closed solvent, liquid an...

68

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...

69

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

70

Influence of solvent on carbene intersystem crossing rates.  

PubMed

The influence of coordinating solvents on singlet-to-triplet carbene intersystem crossing (ISC) rates has been studied with diphenylcarbene (DPC) and para-biphenyltrifluoromethylcarbene (BpCCF 3) by using ultrafast time-resolved spectroscopy. DPC has a triplet ground state in all of the solvents considered, and the concentration of singlet carbene at equilibrium is too small to be measured. It is found that the lifetime of (1)DPC is extended in acetonitrile, benzene, tetrahydrofuran, dichloromethane, and halobenzene solvents relative to cyclohexane. The solvent effect does not well correlate with bulk measures of solvent polarity. The singlet-triplet energy separation of BpCCF 3 is close to zero. The data demonstrates that BpCCF 3 has a triplet ground state in benzene, fluorobenzene, and hexafluorobenzene. Halogenated solvents are found to dramatically retard the rate of ISC in (1)BpCCF 3. We postulate that the empty p orbital of a singlet carbene coordinates with a nonbonding pair of electrons of a halogen atom of the solvent to form a pseudoylide solvent complex, stabilize the singlet carbene, and decrease the singlet-triplet (S-T) energy gap. The "golden rule" of radiationless transitions posits that the smaller the energy gap between the two states, the faster their rate of interconversion. To explain the apparent violation of the golden rule of radiationless transitions for the carbene ISC processes monitored in this study, we propose that the significantly different specific solvation of the singlet and triplet carbenes imposes a Franck-Condon-like factor on the ISC process. Those solvents that most solvate the singlet carbene will also have the greatest structural difference between singlet carbene-solvent complex and their triplet spin isomer-solvent complex, the smallest S-T gap, and the slowest ISC rate. Alternatively, one can propose that a highly solvated singlet carbene must desolvate prior to ISC, and that this requirement decelerates the radiationless transition. PMID:18433130

Wang, Jin; Kubicki, Jacek; Peng, Huolei; Platz, Matthew S

2008-05-21

71

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

72

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)....

73

SOLVENT WASTE REDUCTION ALTERNATIVES  

EPA Science Inventory

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

74

Supercritical solvent coal extraction  

NASA Technical Reports Server (NTRS)

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

Compton, L. E. (inventor)

1984-01-01

75

COORDINATED AV.  

ERIC Educational Resources Information Center

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

CLEAVES, PAUL C.; AND OTHERS

76

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

77

Cleaning without chlorinated solvents  

NASA Technical Reports Server (NTRS)

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

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

1995-01-01

78

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

E-print Network

Hydrogen Bond Lifetimes and Energetics for Solute/Solvent Complexes Studied with 2D-IR Vibrational@stanford.edu Abstract: Weak hydrogen-bonded solute/solvent complexes are studied with ultrafast two the dissociation and formation rates of the hydrogen-bonded complexes. The dissociation rates of the weak hydrogen

Fayer, Michael D.

79

Solvent interactions of halophilic malate dehydrogenase.  

PubMed

Malate dehydrogenase from the extreme halophilic Haloarcula marismortui (Hm MalDH) is an acidic protein that is unstable below molar salt concentrations. The solvated folded protein was studied by small-angle neutron scattering in solvents containing salt: NaCl, NaCH(3)CO(2), KF, NH(4)Cl, NH(4)CH(3)CO(2), (NH(4))(2)SO(4), MgCl(2), and MgSO(4). It was found that the global solvent interactions depend mainly on the nature of the cation. Complementary mass density measurements in MgCl(2), NaCl, NaCH(3)CO(2), and (NH(4))(2)SO(4) allowed determining the partial molal volumes of the protein, which were found to increase slightly with the salt, and the preferential salt binding parameters for each solvent condition. These are strongly dependent on the cation type and salt concentration. Hm MalDH can be modeled as an invariant particle binding 4100 water molecules in MgCl(2) and 2000 +/- 200 in NaCl, NaCH(3)CO(2), or (NH(4))(2)SO(4). The number of salt molecules associated to the particle decreases from about 85 to 0 in the order MgCl(2) > NaCl = NaCH(3)CO(2) > (NH(4))(2)SO(4). Alternatively, we considered exchangeable sites for water and salt with the effects of solvent nonideality. It does not change the description of the solvent interactions. Solvent anions act on Hm MalDH stability through a limited number of strong binding sites, as those seen at the interfaces of Hm MalDH by crystallography. Cations would act through some strong and numerous weak binding sites defined on the folded protein, in possible addition to nonspecific hydration effects. PMID:12403625

Ebel, Christine; Costenaro, Lionel; Pascu, Mihaela; Faou, Pierre; Kernel, Blandine; Proust-De Martin, Flavien; Zaccai, Giuseppe

2002-11-01

80

Coordinate Plane  

NSDL National Science Digital Library

5th Grade Math State core Standard 3, Objective 2a: Locate points defined by ordered pairs of integers. Congratulations for earning a game day in the computer lab! Remember that even though it is game day I expect you to stay on task and follow directions. We have been talking in math about graphing integers on the coordinate plane. The games for today require that ...

Miss Zilles

2007-10-31

81

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

82

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

PubMed Central

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

Ortuño, Manuel A

2013-01-01

83

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

84

Halogenated solvent remediation  

DOEpatents

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

Sorenson, Kent S.

2004-08-31

85

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

86

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

87

How Do Teachers Coordinate Their Work? A Framing Approach  

ERIC Educational Resources Information Center

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

Dumay, Xavier

2014-01-01

88

Molecular-based study of solutions in supercritical solvents  

SciTech Connect

Behavior and properties of solutions in supercritical (SC) solvents are related to microscopic structures, and the structure and properties of typical attractive SC solutions have been well-studied both experimentally and theoretically. New and interesting properties, however, have been uncovered in recent studies of dilute repulsive and weakly attractive SC solutions. Such repulsive and weakly attractive solutions are encountered in practice when relatively volatile substances are present in a SC solvent. Specific examples of practical importance include organic molecules in SC water and light gases in SC carbon dioxide. We report a study of the microscopic structure and thermodynamic properties of these less-known repulsive and weakly attractive SC mixtures. Results are based on integral equation calculations for model systems and illustrate the qualitative behaviors that may be expected in practice. The results are based on Ornstein-Zernike integral equation calculations in the Percus-Yevick approximation applied to dilute, binary Lennard-Jones mixtures. The microscopic structures calculated (pair correlation functions) are related to the thermodynamic properties through the fluctuation integrals of Kirkwood-Buff theory. Whether the system behaves as a repulsive mixture or a weakly attractive mixture depends on size of solute molecule and strength of its intermolecular attraction relative to the solvent molecule as well as on the temperature and density of the system relative to the critical temperature and density of the solvent.

Shah, V.M. [Tennessee Univ., Knoxville, TN (United States). Dept. of Chemical Engineering; Lee, L.L. [Oklahoma Univ., Norman, OK (United States). School of Chemical Engineering and Materials Science; Cochran, H.D. [Oak Ridge National Lab., TN (United States)]|[Oklahoma Univ., Norman, OK (United States). School of Chemical Engineering and Materials Science

1994-09-01

89

Organic solvent topical report  

SciTech Connect

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

Cowley, W.L.

1998-04-30

90

Organic solvent topical report  

SciTech Connect

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

COWLEY, W.L.

1999-05-13

91

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...

92

Solvent extraction processes compared  

Microsoft Academic Search

Solvent ectraction processes are often difficult to compare. Waste processors need to understand how the process works in order to make a good choice for waste stream applications. The technologies used by Carver-Greenfield Process, B.E.S.T., and NuKEM`s method are described.

Kogut

1994-01-01

93

Solvent extraction processes compared  

SciTech Connect

Solvent ectraction processes are often difficult to compare. Waste processors need to understand how the process works in order to make a good choice for waste stream applications. The technologies used by Carver-Greenfield Process, B.E.S.T., and NuKEM`s method are described.

Kogut, K.E. [Kogut Engineering, Concord, CA (United States)

1994-04-01

94

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

95

Heavy Flavor Weak Decays  

E-print Network

Weak decays of heavy flavor hadrons play a special role in our understanding of physics of the Standard Model and beyond. The measured quantities, however, result from a complicated interplay of weak and strong interactions. Weak leptonic and semileptonic decays are reasonably well understood, whereas weak hadronic decays present challenges to theory. In this talk, we review the present status of exclusive weak decays of charm and bottom hadrons.

R. C. Verma

1997-03-04

96

Glove permeation by organic solvents  

SciTech Connect

The vapor penetration of 29 common laboratory solvents on 28 protective gloves has been tested and measured using gas-phase, infrared spectrophotometric techniques to determine the permeation characteristics. Five different types of permeation behavior were identified. No one glove offered complete protection against all the solvents tested. The permeation rate of the solvent was found to be inversely proportional to glove thickness for a given manufacturer's material. Of two solvent mixtures tested, one exhibited a large, positive, synergistic rate.

Nelson, G.O.; Lum, B.Y.; Carlson, G.J.; Wong, C.M.; Johnson, J.S.

1981-03-01

97

PARIS II: DESIGNING GREENER SOLVENTS  

EPA Science Inventory

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

98

Glove permeation by organic solvents  

Microsoft Academic Search

We have tested and measured the vapor penetration of 29 common laboratory solvents on 28 protective gloves using gas-phase, infrared spectrophotometric techniques to determine the permeation characteristics. Five different types of permeation behavior were identified. No one glove offered complete protection against all the solvents tested. The permeation rate of the solvent was found to be inversely proportional to glove

G. O. NELSON; B. Y. LUM; G. J. CARLSON; C. M. WONG; J. S. JOHNSON

1981-01-01

99

Solvent extraction in nuclear technology  

Microsoft Academic Search

Some aspects of solvent extraction chemistry in the field of nuclear technology are briefly reviewed. Applications of solvent extraction in actinide recovery and purification, radionuclide production, and reactor materials preparation are summarized. The need for new, more selective, solvent extraction reagents is presented via examples of recent work with bifunctional organophosphorus reagents applied to the removal of actinides from acidic

J. D. Navratil

1986-01-01

100

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

101

SOLVENT FIRE BY-PRODUCTS  

SciTech Connect

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

Walker, D; Samuel Fink, S

2006-05-22

102

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

103

Computer simulation of bottle brush polymers with flexible backbone: Good solvent versus Theta solvent conditions  

E-print Network

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

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

2011-11-02

104

Collective Dynamics of an End-Grafted Polymer Brush in Solvents of Varying Quality  

NASA Astrophysics Data System (ADS)

The dynamic structure of a chemically end-grafted polystyrene brush bathed in solvents of varying interactions was studied by evanescent wave dynamic light scattering. It reveals distinct behavior under good and poor solvent conditions. The cooperative diffusion is a generic feature of a good solvent environment, whereas a second slow relaxation mode appears in the theta solvent regime. Its characteristics resemble self-diffusion of clusters in a gel while weak concentration fluctuations in the polymer brush decay similarly to a semidilute polymer solution.

Yakubov, G. E.; Loppinet, B.; Zhang, H.; Rühe, J.; Sigel, R.; Fytas, G.

2004-03-01

105

Weak scale supersymmetry  

SciTech Connect

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

Hall, L.J. (Lawrence Berkeley Lab., CA (USA) California Univ., Berkeley, CA (USA). Dept. of Physics)

1990-11-12

106

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

107

Diaphragmatic weakness and paralysis  

Microsoft Academic Search

Diaphragmatic weakness implies a decrease in the strength of the diaphragm. Diaphragmatic paralysis is an extreme form of\\u000a diaphragmatic weakness. Diaphragmatic paralysis is an uncommon clinical problem while diaphragmatic weakness, although uncommon,\\u000a is probably frequently unrecognized because appropriate tests to detect its presence are not performed. Weakness of the diaphragm\\u000a can result from abnormalities at any site along its neuromuscular

Pearce G. Wilcox; Richard L. Pardy

1989-01-01

108

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

109

Solvent Fractionation of Lignin  

SciTech Connect

Lignin is a highly abundant source of renewable carbon that can be considered as a valuable sustainable source of biobased materials. The major issues for the commercial production of value added high performance lignin products are lignin s physical and chemical heterogenities. To overcome these problems, a variety of procedures have been developed to produce pure lignin suitable for high performace applications such as lignin-derived carbon materials. However, most of the isolation procedures affect lignin s properties and structure. In this chapter, a short review of the effect of solvent fractionation on lignin s properties and structure is presented.

Chatterjee, Sabornie [ORNL; Saito, Tomonori [ORNL

2014-01-01

110

Coupling of protein dynamics with the solvent  

NASA Astrophysics Data System (ADS)

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

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

2003-03-01

111

Conformational transitions of a weak polyampholyte  

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

112

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

113

Coumarin6 interaction with solvents  

NASA Astrophysics Data System (ADS)

Bonding arrangements and changes induced by chemicals in structure/bonding of laser dyes molecule can be investigated from the study of IR spectra. These changes are expected to depend upon the nature of interacting solvent. In the present study, we have studied the FTIR spectra of Coumarin6 in powder form and in different solvents in order to investigate the effect of solvents on Coumarin6 molecule by observing the changes in the spectra. This study may provide the deeper understanding of the sensing properties of Coumarin 6 and also the dependence of its fluorescence and, therefore, lasing property on solvents.

Sharma, Amit

2013-06-01

114

Optimized coordinates in vibrational coupled cluster calculations  

NASA Astrophysics Data System (ADS)

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; Yagi, Kiyoshi; Christiansen, Ove

2014-04-01

115

High Pressure Studies of Solvent Effects on Anthracene Spectra  

PubMed Central

Measurements have been made of the effect of pressure on the peak location and peak shape for anthracene in a variety of liquid and plastic environments; both absorption and fluorescence studies were made. The results are discussed from two standpoints: in terms of the dielectric model and of a configuration coordinate model. For the latter model, the change of configuration coordinate (volume decrease of the system upon electronic excitation) is shown to correlate well with the product of the compressibility and polarizability of the solvent. For the dielectric model, it is found that the change of cavity volume with density is complex. However, the relative cavity volume obtained from emission measurements was consistently 10-15% smaller than that obtained from absorption. The cavity volume decreased with increasing polarizability of the solvent, and results obtained from absorption and emission were quite consistent in this regard. PMID:16592204

Okamoto, B. Y.; Drickamer, H. G.

1974-01-01

116

Three-coordinate, luminescent, water-soluble gold(I) phosphine complexes: structural characterization and photoluminescence  

E-print Network

characterization and photoluminescence properties in aqueous solution Zerihun Assefa a , Jennifer M. Forward The photoluminescent properties of several types of three-coordinate gold(I) complexes in organic solvents

Abdou, Hanan E.

117

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

118

Solute-Solvent Complex Kinetics and Thermodynamics Probed by 2D-IR Vibrational Echo Chemical Exchange Spectroscopy  

E-print Network

with previous observations on eight phenol/solvent complexes with enthalpies of formation from -0.6 to -2.5 kcal, five silanol complexes and eight phenol complexes, fall on the same line. In addition, features of 2D solvation shell of a solute. The typical organic solute-solvent interaction energy is weak, less than 5 kcal

Fayer, Michael D.

119

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

120

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...

121

WASH SOLVENT REUSE IN PAINT PRODUCTION  

EPA Science Inventory

This project evaluated solvent used to clean paint manufacture equipment for its utility in production of subsequent batches of solvent-borne paint. eusing wash solvent would reduce the amount of solvent disposed of as waste. he evaluation of this wash-solvent recovery technology...

122

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. ...

Mr Clark

2012-10-31

123

Reflections on Statewide Coordination.  

ERIC Educational Resources Information Center

Coordinating boards, no matter how carefully constructed, are super bureaucracies. Battles inevitably ensue between a coordinating board and the institutions that it proports to coordinate. Strong coordinating boards work best in large industrialized states, states with populations running into the many millions and spending hundreds of millions…

Sample, Steven B.

124

Weak Lie 2-bialgebra  

E-print Network

We introduce the notion of weak Lie 2-bialgebra. Roughly, a weak Lie 2-bialgebra is a pair of compatible 2-term $L_\\infty$-algebra structures on a vector space and its dual. The compatibility condition is described in terms of the big bracket. We prove that (strict) Lie 2-bialgebras are in one-one correspondence with crossed modules of Lie bialgebras.

Zhuo Chen; Mathieu Stienon; Ping Xu

2013-02-05

125

Weak Lie 2-bialgebra  

E-print Network

We introduce the notion of weak Lie 2-bialgebra. Roughly, a weak Lie 2-bialgebra is a pair of compatible 2-term $L_\\infty$-algebra structures on a vector space and its dual. The compatibility condition is described in terms of the big bracket. We prove that (strict) Lie 2-bialgebras are in one-one correspondence with crossed modules of Lie bialgebras.

Chen, Zhuo; Xu, Ping

2011-01-01

126

Weakly ?-continuous functions  

Microsoft Academic Search

It is the objective of this paper to introduce a new class of generalizations of continuous functions via ‚-open sets called weakly ‚- continuous functions. Moreover, we study some of its fundamental prop- erties. It turns out that weak ‚-continuity is weaker than ‚-continuity (1).

Takashi Noiri; S. Jafari; M. Caldas

1987-01-01

127

GMM with Weak Identification  

Microsoft Academic Search

This paper develops asymptotic distribution theory for GMM estimators and test statistics when some or all of the parameters are weakly identified. General results are obtained and are specialized to two important cases: linear instrumental variables regres- sion and Euler equations estimation of the CCAPM. Numerical results for the CCAPM demonstrate that weak-identification asymptotics explains the breakdown of conventional GMM

James H. Stock; Jonathan H. Wright

2000-01-01

128

Cesium Concentration in MCU Solvent  

SciTech Connect

During Modular Caustic-Side Solvent Extraction (CSSX) Unit (MCU) operations, Cs-137 concentrations in product streams will vary depending on the location in the process and on the recent process conditions. Calculations of cesium concentrations under a variety of operating conditions reveal the following: (1) Under nominal operations with salt solution feed containing 1.1 Ci Cs-137 per gallon, the maximum Cs-137 concentration in the process will occur in the strip effluent (SE) and equal 15-16.5 Ci/gal. (2) Under these conditions, the majority of the solvent will contain 0.005 to 0.01 Ci/gal, with a limited portion of the solvent in the contactor stages containing {approx}4 Ci/gal. (3) When operating conditions yield product near 0.1 Ci Cs-137/gal in the decontaminated salt solution (DSS), the SE cesium concentration will be the same or lower than in nominal operations, but majority of the stripped solvent will increase to {approx}2-3 Ci/gal. (4) Deviations in strip and waste stream flow rates cause the largest variations in cesium content: (a) If strip flow rates deviate by -30% of nominal, the SE will contain {approx}23 Ci/gal, although the cesium content of the solvent will increase to only 0.03 Ci/gal; (b) If strip flow rate deviates by -77% (i.e., 23% of nominal), the SE will contain 54 Ci/gal and solvent will contain 1.65 Ci/gal. At this point, the product DSS will just reach the limit of 0.1 Ci/gal, causing the DSS gamma monitors to alarm; and (c) Moderate (+10 to +30%) deviations in waste flow rate cause approximately proportional increases in the SE and solvent cesium concentrations. Recovery from a process failure due to poor cesium stripping can achieve any low cesium concentration required. Passing the solvent back through the contactors while recycling DSS product will produce a {approx}70% reduction during one pass through the contactors (assuming the stripping D value is no worse than 0.36). If the solvent is returned to the solvent hold tank (containing additional, unstripped solvent), 3.3 tank turnovers will reduce the cesium content by an order of magnitude. Under these conditions, the solvent cesium concentration can be reduced to <0.03 Ci/gal during 8 hours at nominal solvent flow rates (2.8 gpm).

Walker, D

2006-01-18

129

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

NASA Astrophysics Data System (ADS)

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

2014-01-01

130

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

131

The influence of organic sample solvents on the separation efficiency of basic compounds under strong cation exchange mode.  

PubMed

This study investigated the influence of organic sample solvents on separation efficiency of basic compounds under strong cation exchange (SCX) mode. The mixtures of acidic aqueous solution and organic solvent such as acetonitrile, ethanol, methanol and dimethyl sulfoxide (DMSO) were tested as sample solvents. For later-eluting analytes, the increase of sample solvent elution strength was responsible for the decrease of separation efficiency. Thus, sample solvents with weak elution strength could provide high separation efficiencies. For earlier-eluting analytes, the retention of organic sample solvents was the main factor affecting separation efficiency. Weakly retained solvents could provide high separation efficiency. In addition, an optimized approach was proposed to reduce the effect of organic sample solvent, in which low ionic solvent was employed as initial mobile phase in the gradient. At last, the analysis of impurities in hydrophobic drug berberine was performed. The results showed that using acidic aqueous methanol as sample solvents could provide high separation efficiency and good resolution (R>1.5). PMID:25892072

Long, Zhen; Yu, Dongping; Liu, Yanfang; Du, Nana; Tao, Yanduo; Mei, Lijuan; Guo, Zhimou; Liang, Xinmiao

2015-05-01

132

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

133

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...

134

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...

135

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 ...

136

Pigment dispersion in organic solvents  

Microsoft Academic Search

The interactions between pigments, solvents, and additives play a decisive part in the formulation of paints and coatings.\\u000a These interactions were examined by means of calorimetric measurements of the enthalpies of displacement and by determining\\u000a the adsorbed additive amounts of pigments from non-polar solvents. The combination of the two method proved particularly favorable\\u000a for examining the type of interaction between

M. Liphard; W. von Rybinski

137

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

138

Developmental coordination disorder  

MedlinePLUS

Physical education and perceptual motor training are the best ways to treat coordination disorder. Using a computer to take notes may help children who have trouble writing. Children with developmental coordination disorder are three times more likely to ...

139

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

140

Simple Coordinates Game  

NSDL National Science Digital Library

In this activity, students enter in coordinates then the applet places a house at that location, or the location is decided first then the student must enter in the coordinates of the house. This activity allows students to practice with coordinates and ordered pairs in the Cartesian coordinate system. This activity includes supplemental materials, including background information about the topics covered, a description of how to use the application, and exploration questions for use with the java applet.

2011-05-26

141

Cook-Coordinate Plane  

NSDL National Science Digital Library

Become familiar with the coordinate plane. Learn the quadrants and how to graph points and read points on a coordinate plane. You are required to do the assignment and take the quiz. The other resources are to help prepare you for the quiz and book assignment. This is a quick review of the lesson.The Coordinate Plane This is a game to practice plotting and reading points.coordinates game *Assignment: Watch Powerpoint 3.3 and fill in your ...

Miss Cook

2010-10-12

142

Microscopic theory of protein folding rates. II. Local reaction coordinates and chain dynamics  

E-print Network

Microscopic theory of protein folding rates. II. Local reaction coordinates and chain dynamics John paper. Local reaction coordinates are identified as collective growth modes of the unstable fluctuations of the backbone dihedral angles. We find that the folding rate depends linearly on the solvent friction for high

Takada, Shoji

143

MISCELLANEA Spherical Coordinates  

E-print Network

and to denote polar coordinates. Most American calculus texts also utilize in spherical coordinates coordinate. There is however a much more serious problem. Several of the most commonly used calculus texts overnight from driving on the left to driving on the right! We argue that the conflict between the different

144

Cartesian Coordinate System  

NSDL National Science Digital Library

This lesson is designed to develop students' understanding of the Cartesian coordinate plane. Topics include plotting coordinates and slope. This lesson provides links to discussions and activities related to the Cartesian coordinate system as well as suggested ways to integrate them into the lesson. Finally, the lesson provides links to follow-up lessons designed for use in succession with the current one.

2011-05-24

145

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

146

Self-assembled nanostructures of amphiphilic zinc(II) salophen complexes: role of the solvent on their structure and morphology.  

PubMed

This contribution explores the effect of several solvent properties, such as volatility, polarity, and Lewis basicity on the formation of molecular self-assembled nanostructures in the solid state, obtained either by casting of related solutions or by complete solvent evaporation, using seven solvents representative of common classes of coordinating organic solvents, of an amphiphilic Zn(II) Schiff-base complex. In all cases, the existence of well-defined X-ray diffraction patterns, for both the cast and powder samples, indicates a strong tendency towards the molecular self-assembly of such complexes. While nanostructures formed in acetone, THF, pyridine, and DMF have a lamellar organization, those formed in ACN, ethanol, and DMSO exhibit a 2D columnar square structure. Field emission scanning electron microscopy analysis indicates that nanostructures formed in volatile acetone, THF, ACN, and ethanol solvents show a fibrous morphology, while those formed in less volatile pyridine, DMF, and DMSO have a ribbon appearance. Overall, the results indicate that while the formation of such nanostructures is independent of the Lewis basicity of the solvent, the solvent polarity affects their structure - more polar solvents favour higher symmetry structures - and the solvent volatility influences their morphology and ordering in the cast films - lower volatility of the solvent parallels the formation of much more ordered structures. Therefore, the appropriate choice of solvent allows control of the structure, morphology, and ordering of these molecular assemblies. PMID:24875135

Oliveri, Ivan Pietro; Malandrino, Graziella; Di Bella, Santo

2014-07-14

147

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

148

Properties of ionic liquid solvents for catalysis  

Microsoft Academic Search

Ionic liquids are good solvents for catalytic reactions. The rational selection of the appropriate ionic liquid solvent for a particular reaction requires general knowledge of the properties of ionic liquids, and the details of some properties of the specific ionic liquid solvents being considered. The solvent properties of ionic liquids that are relevant to catalysis are discussed, and sources of

John S Wilkes

2004-01-01

149

Coal liquefaction with supercritical solvents  

SciTech Connect

The effect of density on the liquefaction kinetics of a bituminous coal (Bruceton, experimental mine), in the presence of a non-donor solvent (toluene) is examined. The effects of coal rank and type, and liquefaction solvent are also addressed. Donor solvents like piperidine gas higher conversions than non-donor solvents like toluene or water and heavy incorporation of piperidine is found in the soluble products of coal. The temperature (597-698 K), density (0.15-0.60 g/cc), mode of contact and solvent to coal ratio (6-30) had a significant effect on the product distribution. The stirrer speed and the presence of inerts like argon had no measurable effect on the product distribution. Based upon the experimental results, the following model is proposed. A fraction of coal dissolves instantaneously and this fraction increases with an increase in either the temperature or the density of the supercritical fluid. This dissolved fraction then undergoes pyrolysis reactions to give gasses, oils and asphaltenes and these products undergo retrogressive reactions giving char (THF insoluble products). The presence of a donor solvent or molecular hydrogen prevents the retrogressive reactions and a donor solvent reacts chemically with the coal to give greater yields of THF soluble products. A lumped kinetic model is presented to describe this behavior for the toluene-Bruceton bituminous coal system. This model adequately predicts the product distribution for the entire range of parameters used in this study and is completely consistent with the hypothesized liquefaction mechanism. It clearly shows that higher densities can increase both the reaction rate and the maximum conversion obtained.

Deshpande, G.V.

1986-01-01

150

ICU-acquired weakness.  

PubMed

Observational studies of patients receiving prolonged mechanical ventilation and other forms of critical care support have determined acquired neuromuscular disorders to be extremely common. Early studies used electrophysiologic investigations to diagnose critical illness polyneuropathy (CIP) and muscle biopsy to confirm critical illness myopathy (CIM). More recent approaches seek to obviate these invasive techniques and build on a standardized bedside neuromuscular examination to identify patients with acquired weakness syndromes. Serial examination in the alert patient may serve as a reasonable prognosticator for most patients. The importance of ICU-acquired weakness syndromes is supported by the observation that muscle wasting and weakness are among the most prominent long-term complications of survivors of ARDS. In addition, a strong association appears to exist between acquired weakness and protracted ventilator dependence, an important determinant of ICU length of stay. Multivariate analysis has identified several risk factors associated with increased incidence for ICU-acquired weakness, including severe systemic inflammation, medications (specifically, corticosteroids and neuromuscular blocking agents), glycemic control, and immobility. We advocate an approach to this common syndrome that identifies risk factors early in the hope of minimizing their impact. PMID:17494803

Schweickert, William D; Hall, Jesse

2007-05-01

151

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

152

Movement Coordination during Conversation  

PubMed Central

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

153

Dielectric anisotropy in polar solvents under external fields  

E-print Network

We investigate dielectric saturation and increment in polar liquids under external fields. We couple a previously introduced dipolar solvent model to a uniform electric field and derive the electrostatic kernel of interacting dipoles. This procedure allows an unambiguous definition of the liquid dielectric permittivity embodying non-linear dielectric response and correlation effects.We find that the presence of the external field results in a dielectric anisotropy characterized by a two-component dielectric permittivity tensor. The increase of the electric field amplifies the permittivity component parallel to the field direction, i.e. dielectric increment is observed along the field. However, the perpendicular component is lowered below the physiological permittivity, indicating dielectric saturation perpendicular to the field. By comparison with Molecular Dynamics simulations from the literature, we show that the mean-field level dielectric response theory underestimates dielectric saturation. The inclusion of dipolar correlations at the weak-coupling level intensify the mean-field level dielectric saturation and improves the agreement with simulation data at weak electric fields. The correlation-corrected theory predicts as well the presence of a metastable configuration corresponding to the antiparallel alignment of dipoles with the field. This prediction can be verified by solvent-explicit simulations where solvent molecules are expected to be trapped transiently in this metastable state.

Sahin Buyukdagli

2014-12-14

154

Diverse coordination modes in solvated alkali metal phenolates: The crystal structures of rubidium phenolate · 3 phenol and cesium phenolate · 2 phenol  

Microsoft Academic Search

Two alkali metal phenolate\\/phenol complexes are reported. The cations are pseudo-octahedrally coordinated by oxygen atoms and the ?-systems of phenolates and solvent phenols. The ratio of phenolate\\/phenol determines whether the oxygen atom of the phenolate participates in the coordination of the metal. In cesium phenolate·2 phenol, both phenolate and phenol solvent coordinate the metal via oxygen and the ?-system, whereas

Maren Pink; Joachim Sieler

2007-01-01

155

Solvent reorganization energy of electron-transfer reactions in polar solvents  

E-print Network

time L in ET rate constants affected by solvent dynamics.5­7 Also, time-resolved measurementsSolvent reorganization energy of electron-transfer reactions in polar solvents Dmitry V. Matyushova proportional to temperature. The dependence of the solvent reorganization energy on the solvent dipole moment

Matyushov, Dmitry

156

Weak mutually unbiased bases  

E-print Network

Quantum systems with variables in ${\\mathbb Z}(d)$ are considered. The properties of lines in the ${\\mathbb Z}(d)\\times {\\mathbb Z}(d)$ phase space of these systems, are studied. Weak mutually unbiased bases in these systems are defined as bases for which the overlap of any two vectors in two different bases, is equal to $d^{-1/2}$ or alternatively to one of the $d_i^{-1/2},0$ (where $d_i$ is a divisor of $d$ apart from $d,1$). They are designed for the geometry of the ${\\mathbb Z}(d)\\times {\\mathbb Z}(d)$ phase space, in the sense that there is a duality between the weak mutually unbiased bases and the maximal lines through the origin. In the special case of prime $d$, there are no divisors of $d$ apart from $1,d$ and the weak mutually unbiased bases are mutually unbiased bases.

M. Shalaby; A. Vourdas

2012-03-05

157

Solution reaction space Hamiltonian based on an electrostatic potential representation of solvent dynamics.  

PubMed

Quantum chemical solvation models usually rely on the equilibrium solvation condition and is thus not immediately applicable to the study of nonequilibrium solvation dynamics, particularly those associated with chemical reactions. Here we address this problem by considering an effective Hamiltonian for solution-phase reactions based on an electrostatic potential (ESP) representation of solvent dynamics. In this approach a general ESP field of solvent is employed as collective solvent coordinate, and an effective Hamiltonian is constructed by treating both solute geometry and solvent ESP as dynamical variables. A harmonic bath is then attached onto the ESP variables in order to account for the stochastic nature of solvent dynamics. As an illustration we apply the above method to the proton transfer of a substituted phenol-amine complex in a polar solvent. The effective Hamiltonian is constructed by means of the reference interaction site model self-consistent field method (i.e., a type of quantum chemical solvation model), and a mixed quantum/classical simulation is performed in the space of solute geometry and solvent ESP. The results suggest that important dynamical features of proton transfer in solution can be captured by the present approach, including spontaneous fluctuations of solvent ESP that drives the proton from reactant to product potential wells. PMID:21495743

Aono, Shinji; Yamamoto, Takeshi; Kato, Shigeki

2011-04-14

158

A flexible polymer chain in a critical solvent: coil or globule?  

E-print Network

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

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

2014-11-11

159

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

NASA Astrophysics Data System (ADS)

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

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

2015-02-01

160

Solvent Influences on the Molecular Aggregation of Magnesium Aryloxides  

SciTech Connect

Magnesium aryloxides were prepared in a variety of solvents through the reaction of dibutyl magnesium with sterically varied aryl alcohols: 2,6-dimethylphenol (H-DMP), 2,6-diisopropylphenol (H-DIP), and 2,4,6-trichlorophenol (H-TCP). Upon using a sufficiently strong Lewis-basic solvent, the monomeric species Mg(DMP){sub 2}(py){sub 3} (1, py = pyridine), Mg(DIP){sub 2}(THF){sub 3}, (2a, THF = tetrahydrofuran) Mg(TCP){sub 2}(THF){sub 3} (3) were isolated. Each of these complexes possesses a five-coordinate magnesium that adopts a trigonal bipyramidal geometry. In the absence of a Lewis base, the reaction with H-DIP yields a soluble trinuclear complex, [Mg(DIP){sub 2}]{sub 3} (2b). The Mg metal centers in 2b adopt a linear arrangement with a four-coordinate central metal while the outer metal centers are reduced to just three-coordinate. Solution spectroscopic methods suggest that while 2b remains intact, the monomeric species (1, 2a, and 3) are involved in equilibria, which facilitate intermolecular ligand transfer.

ZECHMANN,CECILIA A.; BOYLE,TIMOTHY J.; RODRIGUEZ,MARK A.; KEMP,RICHARD A.

2000-07-14

161

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

162

Reciprocal-space solvent flattening  

PubMed Central

Solvent flattening is a powerful tool for improving crystallographic phases for macromolecular structures obtained at moderate resolution, but uncertainties in the optimal weighting of experimental phases and modified phases make it difficult to extract all the phase information possible. Solvent flattening is essentially an iterative method for maximizing a likelihood function which consists of (i) experimental phase information and (ii) information on the likelihood of various arrangements of electron density in a map, but the likelihood function is generally not explicitly defined. In this work, a procedure is described for reciprocal-space maximization of a likelihood function based on experimental phases and characteristics of the electron-density map. The procedure can readily be applied to phase improvement based on solvent flattening and can potentially incorporate information on a wide variety of other characteristics of the electron-density map. PMID:10531484

Terwilliger, Thomas C.

1999-01-01

163

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

SciTech Connect

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

Lock, Edward A., E-mail: e.lock@ljmu.ac.uk [Liverpool John Moores University, School of Pharmacy and Biomolecular Sciences, Byrom Street, Liverpool (United Kingdom); Zhang, Jing [University of Washington, Department of Pathology, School of Medicine, Seattle, WA (United States)] [University of Washington, Department of Pathology, School of Medicine, Seattle, WA (United States); Checkoway, Harvey [University of Washington, Department of Environmental and Occupational Health Sciences, Seattle, WA (United States)] [University of Washington, Department of Environmental and Occupational Health Sciences, Seattle, WA (United States)

2013-02-01

164

Solvent diffusion into fluoropolymer membranes  

SciTech Connect

Solvent diffusion in polymers is important to the physical properties of the material from processing to end-use and shelf-life. Many aspects of diffusion in polymers have been studied using indirect and direct methods. Du Pont`s fluoropolymers are known for their excellent resistance to a variety of organic solvents. This paper describes the measurement of diffusion coefficients and the derived thermodynamic quantities on four different fluoropolymer membranes with several esters. This information is interpreted in terms of the molecular organization and phase structure. Diffusion coefficients are sensitive to structural changes as well as binding and association phenomena.

Aminabhavi, T.M.; Munnolli, R.S. [Karnatak Univ., Dharwad (India)

1993-12-31

165

Acid Base Titrations in Nonaqueous Solvents and Solvent Mixtures  

Microsoft Academic Search

The acid base determination of different substances by nonaqueous titrations is highly preferred in pharmaceutical analyses since the method is quantitative, exact, and reproducible. The modern interpretation of the reactions in nonaqueous solvents started in the last century, but several inconsistencies and unsolved problems can be found in the literature. The acid base theories of Brønsted Lowry and Lewis as

Lajos Barcza; Ágnes Buvári-Barcza

2003-01-01

166

Imbalanced Weak MHD Turbulence  

E-print Network

MHD turbulence consists of waves that propagate along magnetic fieldlines, in both directions. When two oppositely directed waves collide, they distort each other, without changing their respective energies. In weak MHD turbulence, a given wave suffers many collisions before cascading. "Imbalance" means that more energy is going in one direction than the other. In general, MHD turbulence is imbalanced. A number of complications arise for the imbalanced cascade that are unimportant for the balanced one. We solve weak MHD turbulence that is imbalanced. Of crucial importance is that the energies going in both directions are forced to equalize at the dissipation scale. We call this the "pinning" of the energy spectra. It affects the entire inertial range. Weak MHD turbulence is particularly interesting because perturbation theory is applicable. Hence it can be described with a simple kinetic equation. Galtier et al. (2000) derived this kinetic equation. We present a simpler, more physical derivation, based on the picture of colliding wavepackets. In the process, we clarify the role of the zero-frequency mode. We also explain why Goldreich & Sridhar claimed that perturbation theory is inapplicable, and why this claim is wrong. (Our "weak" is equivalent to Goldreich & Sridhar's "intermediate.") We perform numerical simulations of the kinetic equation to verify our claims. We construct simplified model equations that illustrate the main effects. Finally, we show that a large magnetic Prandtl number does not have a significant effect, and that hyperviscosity leads to a pronounced bottleneck effect.

Yoram Lithwick; Peter Goldreich

2002-08-02

167

Organic solvent desorption from two tegafur polymorphs.  

PubMed

Desorption behavior of 8 different solvents from ? and ? tegafur (5-fluoro-1-(tetrahydro-2-furyl)uracil) has been studied in this work. Solvent desorption from samples stored at 95% and 50% relative solvent vapor pressure was studied in isothermal conditions at 30 °C. The results of this study demonstrated that: solvent desorption rate did not differ significantly for both phases; solvent desorption in all cases occurred faster from samples with the largest particle size; and solvent desorption in most cases occurred in two steps. Structure differences and their surface properties were not of great importance on the solvent desorption rates because the main factor affecting desorption rate was sample particle size and sample morphology. Inspection of the structure packing showed that solvent desorption rate and amount of solvent adsorbed were mainly affected by surface molecule arrangement and ability to form short contacts between solvent molecule electron donor groups and freely accessible tegafur tetrahydrofuran group hydrogens, as well as between solvents molecule proton donor groups and fluorouracil ring carbonyl and fluoro groups. Solvent desorption rates of acetone, acetonitrile, ethyl acetate and tetrahydrofuran multilayers from ? and ? tegafur were approximately 30 times higher than those of solvent monolayers. Scanning electron micrographs showed that sample storage in solvent vapor atmosphere promotes small tegafur particles recrystallization to larger particles. PMID:24060368

Bobrovs, Raitis; Acti?š, Andris

2013-11-30

168

OPUS: Preventing weak password choices  

Microsoft Academic Search

A common problem with systems that use passwords for auth- entication is that users choose weak passwords. Weak passwords are passwords that are easy to guess, simple to derive, or likely to be found in a dictionary attack. Thus, the choice of weak passwords may lead to a compromised system. Methods exist to prevent users from selecting and using weak

Eugene H. Spafford

1992-01-01

169

Tax Coordination and Unemployment  

Microsoft Academic Search

This paper analyses the implications of unemployment for fiscal competition and tax coordination among small open economies.\\u000a Unemployment is modeled as resulting from wage bargaining. The analysis focuses on the effect of labour and capital tax coordination\\u000a on welfare. We show that, while coordinated capital and labour tax increases unambiguously raise welfare if labour markets\\u000a are competitive, different results emerge

Clemens Fuest; Bernd Huber

1999-01-01

170

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

171

Replacement solvents for use in chemical synthesis  

DOEpatents

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

Molnar, Linda K. (Philadelphia, PA); Hatton, T. Alan (Sudbury, MA); Buchwald, Stephen L. (Newton, MA)

2001-05-15

172

Chronic glomerulonephritis and organic solvents  

Microsoft Academic Search

Fifty patients with histologically confirmed chronic glomerulonephritis (34 males, 16 females, average age 42 years) and 50 control patients, age and sex-matched, with a variety of internal diseases, were selected. Both cases and controls completed an extensive questionnaire and additional information was sampled by means of a personal interview, especially concerning the exposure to organic solvents. In contrast to three

Gert Laan

1980-01-01

173

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

174

Risk assessment for halogenated solvents  

SciTech Connect

A recent development in the cancer risk area is the advent of biologically based pharmacokinetic and pharmacodynamic models. These models allow for the incorporation of biological and mechanistic data into the risk assessment process. These advances will not only improve the risk assessment process for halogenated solvents but will stimulate and guide basic research in the biological area.

Travis, C.C.

1988-01-01

175

Weak Gravitational Lensing  

NASA Astrophysics Data System (ADS)

This chapter reviews the data mining methods recently developed to solve standard data problems in weak gravitational lensing. We detail the different steps of the weak lensing data analysis along with the different techniques dedicated to these applications. An overview of the different techniques currently used will be given along with future prospects. Until about 30 years ago, astronomers thought that the Universe was composed almost entirely of ordinary matter: protons, neutrons, electrons, and atoms. The field of weak lensing has been motivated by the observations made in the last decades showing that visible matter represents only about 4-5% of the Universe (see Figure 14.1). Currently, the majority of the Universe is thought to be dark, that is, does not emit electromagnetic radiation. The Universe is thought to be mostly composed of an invisible, pressure less matter - potentially relic from higher energy theories - called "dark matter" (20-21%) and by an even more mysterious term, described in Einstein equations as a vacuum energy density, called "dark energy" (70%). This "dark" Universe is not well described or even understood; its presence is inferred indirectly from its gravitational effects, both on the motions of astronomical objects and on light propagation. So this point could be the next breakthrough in cosmology. Today's cosmology is based on a cosmological model that contains various parameters that need to be determined precisely, such as the matter density parameter Omega_m or the dark energy density parameter Omega_lambda. Weak gravitational lensing is believed to be the most promising tool to understand the nature of dark matter and to constrain the cosmological parameters used to describe the Universe because it provides a method to directly map the distribution of dark matter (see [1,6,60,63,70]). From this dark matter distribution, the nature of dark matter can be better understood and better constraints can be placed on dark energy, which affects the evolution of structures. Gravitational lensing is the process by which light from distant galaxies is bent by the gravity of intervening mass in the Universe as it travels toward us. This bending causes the images of background galaxies to appear slightly distorted, and can be used to extract important cosmological information. In the beginning of the twentieth century, A. Einstein predicted that massive bodies could be seen as gravitational lenses that bend the path of light rays by creating a local curvature in space time. One of the first confirmations of Einstein's new theory was the observation during the 1919 solar eclipse of the deflection of light from distant stars by the sun. Since then, a wide range of lensing phenomena have been detected. The gravitational deflection of light by mass concentrations along light paths produces magnification, multiplication, and distortion of images. These lensing effects are illustrated by Figure 14.2, which shows one of the strongest lenses observed: Abell 2218, a very massive and distant cluster of galaxies in the constellation Draco. The observed gravitational arcs are actually the magnified and strongly distorted images of galaxies that are about 10 times more distant than the cluster itself. These strong gravitational lensing effects are very impressive but they are very rare. Far more prevalent are weak gravitational lensing effects, which we consider in this chapter, and in which the induced distortion in galaxy images is much weaker. These gravitational lensing effects are now widely used, but the amplitude of the weak lensing signal is so weak that its detection relies on the accuracy of the techniques used to analyze the data. Future weak lensing surveys are already planned in order to cover a large fraction of the sky with high accuracy, such as Euclid [68]. However, improving accuracy also places greater demands on the methods used to extract the available information.

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

2012-03-01

176

Weak Polarized Electron Scattering  

NASA Astrophysics Data System (ADS)

Scattering polarized electrons provides an important probe of the weak interactions. Precisely measuring the parity-violating left–right cross-section asymmetry (ALR) is the goal of a number of experiments that have recently been completed or are in progress. The experiments are challenging, given that ALR is small, typically between 10?4 and 10?8. By carefully choosing appropriate targets and kinematics, one can isolate various pieces of the weak Lagrangian, providing a search for physics beyond the Standard Model. For other choices, unique features of the strong interaction are being 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.

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

2014-10-01

177

Sequential weak measurement  

NASA Astrophysics Data System (ADS)

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

Mitchison, Graeme; Jozsa, Richard; Popescu, Sandu

2007-12-01

178

General Weak Random Sources  

Microsoft Academic Search

The following model for a weak random source is considered. The source is asked only once for R bits, and the source outputs an R-bit string such that no string has probability more than 2 -?R of being output. for some fixed ?>0. A pseudorandom generator that runs in time nO(log n) and simulates RP using as a seed a

David Zuckerman

1990-01-01

179

A Linguistic Coordinator.  

ERIC Educational Resources Information Center

Linguistic acquisition as a mutual objective in the foreign language classroom and in the language laboratory leads to the conceptualization of duties proper to a linguistic coordinator. Distinct from the chairman of the department and the laboratory director, the linguistic coordinator's function and educational preparation described in this…

Reid, Constance

1968-01-01

180

National centre to coordinate  

E-print Network

National centre to coordinate AIDS drug tests set forUBC BY CONNIE FILLETll UBC's Faculty of Medicinehas been chosen to coordinate nationwide testing of all newAIDS drugs and vaccines. A National HIV'sHospital,a teachinghospital of the university. The network will hasten test- ing of thedrugs, provide rapid evaluation

Farrell, Anthony P.

181

6. Coordination and control.  

PubMed

Any complex operation requires a system for management. In most societies, disaster management is the responsibility of the government. Coordination and control is a system that provides the oversight for all of the disaster management functions. The roles and responsibilities of a coordination and control centre include: (1) planning; (2) maintenance of inventories; (3) activation of the disaster response plan; (4) application of indicators of function; (5) surveillance; (6) information management; (7) coordination of activities of the BSFs; (8) decision-making; (9) priority setting; (10) defining overarching goal and objectives for interventions; (11) applying indicators of effectiveness; (12) applying indicators of benefit and impact; (13) exercising authority; (14) managing resources; (15) initiating actions; (16) preventing influx of unneeded resources; (17) defining progress; (18) providing information; (19) liasing with responding organisations; and (20) providing quality assurance. Coordination and control is impossible without communications. To accomplish coordination and control, three factors must be present: (1) mandate; (2) power and authority; and (3) available resources. Coordination and control is responsible for the evaluation of the effectiveness and benefits/impacts of all interventions. Coordination and control centres (CCCs) are organised hierarchically from the on-scene CCCs (incident command) to local provincial to national CCCs. Currently, no comprehensive regional and international CCCs have been universally endorsed. Systems such as the incident command system, the unified command system, and the hospital incident command system are described as are the humanitarian reform movement and the importance of coordination and control in disaster planning and preparedness. PMID:24785803

2014-05-01

182

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

183

IVS Technology Coordinator Report  

NASA Technical Reports Server (NTRS)

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

Whitney, Alan

2013-01-01

184

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

185

AREA COORDINATOR RESIDENTIAL EDUCATION  

E-print Network

. The Ingram Commons houses the entire first year class in a residential college type environment. The IngramAREA COORDINATOR RESIDENTIAL EDUCATION VANDERBILT UNIVERSITY, NASHVILLE, TENNESSEE The Office of Housing and Residential Education at Vanderbilt University is seeking applicants for an Area Coordinator

Bordenstein, Seth

186

Dipolar correlations in structured solvents under nanoconfinement  

E-print Network

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.

Sahin Buyukdagli; Ralf Blossey

2014-05-26

187

Dipolar correlations in structured solvents under nanoconfinement.  

PubMed

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

Buyukdagli, Sahin; Blossey, Ralf

2014-06-21

188

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

189

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.

190

Structure modulation of manganese coordination polymers consisting of 1,4-naphthalene dicarboxylate and 1,10-phenanthroline.  

PubMed

Three new manganese coordination polymers, {[Mn2(1,4-NDC)2(phen)2](H2O)}n (1), [Mn2(1,4-NDC)2(phen)(H2O)]n (2) and {[Mn4(1,4-NDC)4(phen)4](DMF)2}n (3) (1,4-H2NDC = 1,4-naphthalene dicarboxylic acid; phen = 1,10-phenanthroline; DMF = N,N-dimethylformamide), have been synthesized solvo/hydrothermally. 1,4-NDC(2-) ligands adopt different coordination modes under different solvents and concentrations which promotes different crystal structure formation. X-ray crystal structural data reveal that compounds 1, 2 and 3 crystallize in monoclinic space groups C2/c, P21/c and C2/c, respectively. Compound 1 has Mn2 dimers connected by 1,4-NDC(2-) linkers, packing into a 2D structure in a grid pattern. Compound 2 has a three-dimensional (3D) structure which is constructed by Mn2 dimers and 1,4-NDC(2-) linkers. Each MnO4N2 node of compound 3 is linked to another by 1,4-NDC(2-) ligands to form a two-dimensional (2D) structure. Variable-temperature magnetic susceptibilities of compounds 1-3 exhibit overall weak antiferromagnetic coupling between the adjacent Mn(II) ions. PMID:24756312

Lou, Yongbing; Wang, Jingjing; Tao, Yinhua; Chen, Jinxi; Mishima, Akio; Ohba, Masaaki

2014-06-14

191

Luminescence change by the solvent of crystallization, solvent reorganization, and vapochromism of neutral dicyanoruthenium(II) complex in the solid state.  

PubMed

The "solvent effect" on the solid-state luminescence of a neutral complex, [Ru(dbb)(2)(CN)(2)] (dbb = 4,4'-di-tert-butyl-2,2'-bipyridine), was presented. The crystals of this complex showed a variety of luminescence color from orange to dark-red, depending on the acceptor number of the solvent included in the crystal as a solvent of crystallization. The luminescence change was very similar to the solvatochromism in solution, which was attributed to the local donor-acceptor interaction between the CN group and the solvent molecules. The dynamic shift observed in the transient emission spectrum of the crystalline powder was accounted for by the solvent molecule reorganization. X-ray crystallography of [Ru(dbb)(2)(CN)(2)].3(CH(3))(2)CO showed the complex molecule having an approximate C(2) symmetry and very weak interactions between the acetone molecules and the CN groups. A three-dimensional network constructed by acetone molecules was observed in the hydrophobic space consisting of t-butyl groups in dbb ligands. A thin film of the complex showed vapochromic behavior such that the luminescence changed depending on the solvent of crystallization. This suggests a capability for organic molecule discrimination using the complex in the solid state. PMID:20088502

Abe, Taichi; Suzuki, Takayoshi; Shinozaki, Kazuteru

2010-02-15

192

Solvent Extraction of Furfural From Biomass  

NASA Technical Reports Server (NTRS)

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

Humphrey, M. F.

1984-01-01

193

Ionic liquids: Green solvents for nonaqueous biocatalysis  

Microsoft Academic Search

Ionic liquids hold potential as green solvents because of their lack of vapour pressure, and are opening up a burgeoningly new field of nonaqueous enzymology. As compared to those observed in conventional organic solvents, enzymes in ionic liquids have presented enhanced activity, stability, and selectivity. Advantages of using ionic liquids over the use of normal organic solvents as reaction medium

Zhen Yang; Wubin Pan

2005-01-01

194

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

195

Crystallization of polymorphs: the effect of solvent  

Microsoft Academic Search

The effect of solvent in crystallization of polymorphs has been studied using the drug sulphathiazole as a model compound. The solubilities of the four polymorphic forms of sulphathiazole were determined as a function of temperature in various solvents. Within the temperature ranges studied, the rank order of solubility of the polymorphs was the same in all solvent systems. On the

S. Khoshkhoo; J. Anwar

1993-01-01

196

New solvent improves acid job performance  

Microsoft Academic Search

A six month lab and field study has demonstrated the effectiveness of a new micellar acid solvent that converts acids used in well cleaning and stimulation operations into a powerful, low-cost solvent. The combined detergent, wetting and solvent properties imparted by the chemical are discussed in this article. And case histories provide evidence of the additive's effectiveness when subjected to

T. M. Brown; J. B. Dobbs

1983-01-01

197

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

198

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

DOEpatents

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

Bohnert, George W. (Harrisonville, MO); Hand, Thomas E. (Lee's Summit, MO); DeLaurentiis, Gary M. (Jamestown, CA)

2009-01-06

199

Relationships Among Solvent Softness Scales  

Microsoft Academic Search

Quantitative measures of solvent softness, in the sense of Pearson's hard-softacid-base (HSAB) concept, are considered using three scales: the µ scale, basedon the Gibbs energies of transfer of selected ions, the Raman wavenumber shiftof HgBr2 (the Ds scale), and the difference between the IR wavenumber shift ofthe C-I stretch of ICN and the O-H stretch of phenol. Raman and IR

Ting Chen; Glenn Hefter; Yizhak Marcus

2000-01-01

200

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.

201

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

202

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

203

SOLVENT DISPERSION AND FLOW METER CALCULATION RESULTS  

SciTech Connect

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

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

2013-06-21

204

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

205

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

206

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

207

Kairoscope : coordinating time socially  

E-print Network

If everyone says time is relative, why is it still so rigidly defined? There have been many attempts to address the issue of coordinating schedules, but each of these attempts runs into an issue of rigidity: in order to ...

Martin, Reed Eric

2010-01-01

208

Nadia Elliott Administrative Coordinator  

E-print Network

Nadia Elliott Administrative Coordinator Namrata Shukla Interim Associate Dean International Director Student Assistants Student Assistants Amy D'anna Administrative Analyst Extended Education Louis Evans Contract Manager Amy Lehman Associate Director Florence (Gail) Lu Program Support Services

Su, Xiao

209

Muscular Dystrophy Coordinating Committee  

MedlinePLUS

Muscular Dystrophy Coordinating Committee (MDCC) WE ARE NO LONGER ACCEPTING COMMENTS AND EDITS THROUGH THIS SITE. THIS COPY ... on the Draft 2015 Action Plan for the Muscular Dystrophies Draft 2015 Action Plan (PDF, 1.06MB) Request ...

210

Job Announcement Development Database Coordinator  

E-print Network

Database Coordinator. The Development Database Coordinator is the principle manager of the donor database. The Database Coordinator manages and maintains Holden's / Cleveland Botanical Garden's confidential donor on advances in database management software; provides administrative support for the development department

Isaacs, Rufus

211

Reusability of coordination programs  

Microsoft Academic Search

Isolating computation and communication concerns into separate pure computation and pure coordination modules enhances modularity, understandability, and reusability of parallel and\\/or distributed software. This can be achieved by moving communication primitives (such as SendMessage and ReceiveMessage), which are now commonly scattered in application codes, into separate modules written in a language dedicated to the coordination of processes and the flow

F. Arbab; C. L. Blom; F. J. Burger; C. T. H. Everaars

1996-01-01

212

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

213

Coordination of terpyridine to Li+ in two different ionic liquids.  

PubMed

On the basis of (7)Li NMR experiments, the complex-formation reaction between Li(+) and the tridentate N-donor ligand terpyridine was studied in the ionic liquids [emim][NTf2] and [emim][ClO4] as solvents. For both ionic liquids, the NMR data implicate the formation of [Li(terpy)2](+). Density functional theory calculations show that partial coordination of terpyridine involving the coordination of a solvent anion can be excluded. In contrast to the studies in solution, X-ray diffraction measurements led to completely different results. In the case of [emim][NTf2], the polymeric lithium species [Li(terpy)(NTf2)]n was found to control the stacking of this complex, whereas crystals grown from [emim][ClO4] exhibit the discrete dimeric species [Li(terpy)(ClO4)]2. However, both structures indicate that each lithium ion is formally coordinated by one terpy molecule and one solvent anion in the solid state, suggesting that charge neutralization and ? stacking mainly control the crystallization process. PMID:24187986

Pokorny, Klaus; Schmeisser, Matthias; Hampel, Frank; Zahl, Achim; Puchta, Ralph; van Eldik, Rudi

2013-11-18

214

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

215

Dynamic Consistency Between Value and Coordination Models Research Issues  

E-print Network

. This is sufficient for equal concepts, while weakly related concepts, e.g. related to runtime behavior of viewpoints to the runtime behavior between value and coordination viewpoints on behalf of an example. In partic- ular both models indeed describe the same cooperation, Supported by the Netherlands Organisation

Ulm, Universität

216

Dynamic Consistency between Value and Coordination Models -Research Issues  

E-print Network

. This is sufficient for equal concepts, while weakly related concepts, e.g. related to runtime behavior of viewpoints to the runtime behavior between value and coordination viewpoints on behalf of an example. In particular commercial boundaries. The value model abstracts from Supported by the Netherlands Organisation

Ulm, Universität

217

Performance Evaluation of Downlink Interference Coordination Techniques in LTE Networks  

Microsoft Academic Search

This paper presents a joint study of several intercell interference coordination strategies considering both static and dynamic approaches, and with different adjustments in their basic parameters. A wide evaluation is presented with special emphasis on the efficiency vs. fairness tradeoff. Besides, additional performance metrics have been considered as enablers of a full understanding of the strengths and weaknesses of each

David González González; Mario Garcia-Lozano; Virginia Corvino; Silvia Ruiz-Boque; Joan J. Olmos

2010-01-01

218

On Gravitational anomaly and Hawking radiation near weakly isolated horizon  

E-print Network

Based on the idea of the work by Wilczek and his collaborators, we consider the gravitational anomaly near weekly 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 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 black hole horizon.

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

2008-01-09

219

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

220

Biological markers of solvent exposure  

SciTech Connect

The important limitation of many epidemiologic studies is the relative inaccuracy of the assessment of the magnitude of exposure. For some solvents, the concentration in biological media is an indication of the internal exposure and is an indirect indication of the health risk, at least for acute effects. For long-term effects, e.g., carcinogenicity, biological monitoring data can also be used as showed with the individual occupational data on the level of trichloroacetic acid (TCA) in urine. Occupational epidemiology can improve the methods for the assessment of the actual total exposure and health risk in environmental epidemiology by providing higher dose cohort data.

Monster, A.C.

1988-03-01

221

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

222

Self-similar solutions for weak shock reflection  

NASA Astrophysics Data System (ADS)

We present numerical solutions of a two-dimensional Riemann problem for the unsteady transonic small disturbance equation that provides an asymptotic description of the Mach reflection of weak shock waves. We solve the equations in self-similar coordinates, and use local grid refinement near the triple point of the Mach reflection. The solutions contain a sequence of triple points and tiny supersonic patches immediately behind the leading triple point, formed by the reflection of weak shocks and expansion waves between the sonic line and the Mach shock.

Tesdall, Allen Mark

223

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

224

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

225

Solvent winterization of sunflower seed oil  

Microsoft Academic Search

Samples of oil from whole and dehulled sunflower seed were solvent winterized. The solvent mixture, 85% acetone, 15% hexane\\u000a (v\\/v), was used at solvent-in-oil concentrations of 20, 40, and 70% by wt and the samples winterized at 0, ?5, ?10, and ?15\\u000a .01 C for 4 hr. Generally, sunflower oils from whole seed remained free from cloud formation longer on

W. Herbert Morrison; James A. Robertson

1975-01-01

226

Solvent-tolerant bacteria in biocatalysis  

Microsoft Academic Search

The toxicity of fine chemicals to the producer organism is a problem in several biotechnological production processes. In several instances, an organic phase can be used to extract the toxic product from the aqueous phase during a fermentation. With the discovery of solvent-tolerant bacteria, more solvents can now be used in such two-liquid water–solvent systems. We are gaining new insights

Jan A. M de Bont

1998-01-01

227

Coordinate Standard Measurement Development  

SciTech Connect

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

Hanshaw, R.A.

2000-02-18

228

A two-dimensional silver(I) coordination polymer constructed from 4-aminophenylarsonate and triphenylphosphane: poly[[(?3-4-aminophenylarsonato-?(3)N:O:O)(triphenylphosphane-?P)silver(I)] monohydrate].  

PubMed

The title compound, {[Ag(C6H7AsNO3)(C18H15P)]·H2O}n, has been synthesized from the reaction of 4-aminophenylarsonic acid with silver nitrate, in aqueous ammonia, with the addition of triphenylphosphane (PPh3). The Ag(I) centre is four-coordinated by one amino N atom, one PPh3 P atom and two arsonate O atoms, forming a severely distorted [AgNPO2] tetrahedron. Two Ag(I)-centred tetrahedra are held together to produce a dinuclear [Ag2O2N2P2] unit by sharing an O-O edge. 4-Aminophenylarsonate (Hapa(-)) adopts a ?3-?(3)N:O:O-tridentate coordination mode connecting two dinuclear units, resulting in a neutral [Ag(Hapa)(PPh3)]n layer lying parallel to the (10-1) plane. The PPh3 ligands are suspended on both sides of the [Ag(Hapa)(PPh3)]n layer, displaying up and down orientations. There is an R2(2)(8) hydrogen-bonded dimer involving two arsonate groups from two Hapa(-) ligands related by a centre of inversion. Additionally, there are hydrogen-bonding interactions involving the solvent water molecules and the arsonate and amine groups of the Hapa(-) ligands, and weak ?-? stacking interactions within the [Ag(Hapa)(PPh3)]n layer. These two-dimensional layers are further assembled by weak van der Waals interactions to form the final architecture. PMID:25836281

Xiao, Zu Ping; Wen, Meng; Wang, Chun Ya; Huang, Xi He

2015-04-01

229

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

230

Solvent-driven dewetting and rim instability  

NASA Astrophysics Data System (ADS)

An experimental method suitable for reproducible results has been used to investigate dewetting behavior of thin films of solvent-laden polymer. This solvent-driven dewetting enables one to change spreading coefficient by an order of magnitude that is not readily realizable in thermal dewetting and to study polar interactions that have not been fully exploited experimentally. While the film instability is similar to that found in thermal dewetting, the rim instability is quite different. Two different types of the rim instability have been found. With a polar solvent, the rim instability changes from one type to another with increasing film thickness whereas the unstable rim becomes stable for an apolar solvent.

Lee, Sarng H.; Yoo, Pil J.; Kwon, S. Joon; Lee, Hong H.

2004-09-01

231

MCU MATERIALS COMPATIBILITY WITH CSSX SOLVENT  

SciTech Connect

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

Fondeur, F

2006-01-13

232

Effect of solvent viscosity on miscible flooding  

SciTech Connect

This paper presents experimental results for tertiary miscible displacements in strongly water-wet Berea cores. Floods with both continuous solvent and simultaneous solvent/water injection were studied at ambient conditions. Three solvent/oil systems are compared: heptane (0.4 cp) displacing mineral oil (6 cp), tagged heptane displacing heptane, and tagged mineral oil displacing an equal-viscosity mineral oil (6 cp). Saturation profiles from microwave absorption measurements and production histories are presented. The experimental results show that the manner in which residual oil is mobilized and propagated depends on solvent/water injection ratio, oleic/water-phase viscosity ratio, and fractional-flow hysteresis.

Huang, E.T.S. (Unocal Corp. (US))

1992-05-01

233

Process for hydrogenating coal and coal solvents  

DOEpatents

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

Tarrer, Arthur R. (Auburn, AL); Shridharani, Ketan G. (Auburn, AL)

1983-01-01

234

Quantitation of buried contamination by use of solvents. [degradation of silicone polymers by amine solvents  

NASA Technical Reports Server (NTRS)

Spore recovery form cured silicone potting compounds using amine solvents to degrade the cured polymers was investigated. A complete list of solvents and a description of the effect of each on two different silicone polymers is provided.

Pappas, S. P.; Hsiao, Y. C.; Hill, L. W.

1973-01-01

235

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

236

Coordinating Texas Water Research  

E-print Network

Coordinating 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 for increasing supply and/or decreasing demand; (3) the impact of Texas' growth in terms of population, economy

Yang, Zong-Liang

237

Coordinated passivation designs  

Microsoft Academic Search

In two-input (or multi-input) nonlinear systems it may be possible to achieve feedback passivation of a chosen input using the second input (other inputs) to improve the stability properties of the 5rst input's zero dynamics. This 'coordinated passivation' approach is illustratedon a simpli5edmod el of a turbochargedd iesel engine. ? 2002 Elsevier Science Ltd. All rights reserved.

Michael Larsen; Mrdjan Jankovic; Petar V. Kokotovic

2003-01-01

238

Sampling on polar coordinates  

Microsoft Academic Search

2-D sampling on polar coordinates is important for many applications. Two forms of a sampling theorem for concentric circles are established for a bandlimited 2-D function. The location of the samples is prescribed either on equidistant circles or on the roots of the Bessel function J0(). Both methods give comparable results, however the number of samples required for their numerical

N. Myridis; N. Papamarkos; C. Chamzas

1997-01-01

239

Profiling Computing Coordinators.  

ERIC Educational Resources Information Center

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

Edwards, Sigrid; Morton, Allan

240

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

241

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

242

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

243

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

244

Water-Solvent Liquid Junction Potential for some Low-Dielectric Solvents  

Microsoft Academic Search

The redox potentials for the cobalticenium \\/ cobaltocene couple in some low-dielectric solvents perspective as media for electroorganic syntheses and other applications, namely in monoglyme, dichlormetane and diglyme, have been determined. On this basis, the water - solvent liquid junction potentials are evaluated. This opens the possibility to compare the potentials of any electrochemical reaction in these solvents. The data

L. V. Bunakova; L. A. Khanova; V. V. Topolev; L. I. Krishtalik

245

Investigation of aggregation in solvent extraction of lanthanides by acidic extractants (organophosphorus and naphthenic acid)  

Microsoft Academic Search

Three acidic extractants (I) di(2-ethylhexyl) phosphoric acid (HDEHP), (II) 2-ethylhexyl phosphonic acid mono-2-ethylhexyl\\u000a ester (HEHPEHE) and (III) naphthenic acid were employed in preparing the samples for the characterization of the coordination\\u000a structure of lanthanide-extractant complexes and the physicochemica nature of aggregates formed in the organic diluent of\\u000a the solvent extraction systems. Photo correlation spectroscopy (PCS) results on the aggregates formed

Naifu Zhou; Jinguang Wu; Zhijian Yu; R. D. Neuman; Dujin Wang; Guangxian Xu

1997-01-01

246

Noncommutativity in weakly curved background by canonical methods  

SciTech Connect

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

Davidovic, Lj.; Sazdovic, B. [Institute of Physics, University of Belgrade, 11001 Belgrade, P.O. Box 57 (Serbia)

2011-03-15

247

Logistic regression Weakly informative priors  

E-print Network

Logistic regression Weakly informative priors Conclusions Bayesian generalized linear models default p #12;Logistic regression Weakly informative priors Conclusions Classical logistic regression The problem of separation Bayesian solution Logistic regression -6 -4 -2 0 2 4 6 0.00.20.40.60.81.0 y = logit

Gelman, Andrew

248

Effect of solvent quality on coal conversion  

Microsoft Academic Search

One factor governing the success or failure of a coal liquefaction process is the ability of the process to generate and sustain an adequate amount of a sufficiently high quality recycle solvent for continuous operation. To insure continued operability of the plant and to recognize when solvent quality is declining it is useful to have a quantitative measure of the

C. W. Curtis; J. A. Guin; J. F. Jeng; A. R. Tarrer

1979-01-01

249

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

250

Supercritical-Multiple-Solvent Extraction From Coal  

NASA Technical Reports Server (NTRS)

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

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

1983-01-01

251

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

252

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

253

Sluggish solvents and fast reactions: Dynamical arrest  

E-print Network

Sluggish solvents and fast reactions: Dynamical arrest of electron transfer Dmitry Matyushov.... ...not quite, vibrations are done Dynamical arrest: k -1 s e -E /kT 2VET #12; Spectroscopic Evidence ... obs=kET #12; Dynamical Arrest in Liquid Crystals Nematics are sluggish solvents capable

Matyushov, Dmitry

254

SOLVENT DESIGN UNDER VARYING ENVIRONMENTAL REQUIREMENTS  

EPA Science Inventory

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

255

Organic solvent regeneration of granular activated carbon  

Microsoft Academic Search

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

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

1982-01-01

256

SOLVENT RECOVERY AT VANDENBERG AIR FORCE BASE  

EPA Science Inventory

The report gives results of a feasibility study of the addition of vapor recovery and solvent purification equipment for Vandenberg Air Force Base (VAFB) to reuse the large quantities of waste solvent generated in space shuttle preparation operations. (NOTE: Operation of VAFB as ...

257

SOLVENT SWELLING OF DICTYONEMA OIL SHALE  

Microsoft Academic Search

The present work investigates volumetric swelling of Estonian Dictyonema oil shale, as a representative of black shales of the Baltoscandian basin, in 22 solvents. This study shows that kerogen of Dictyonema oil shale is charac- terized by a low degree of swelling indicating a highly cross-linked structure. The relatively high swellability in high Guttmann's electron donor number solvents indicates the

K KILK; N SAVEST; J HRULJOVA; E TEARO; S. KAMENEV; V. OJA

2010-01-01

258

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...

259

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...

260

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, ...

261

EXPERIENCES IN DESIGNING SOLVENTS FOR THE ENVIRONMENT  

EPA Science Inventory

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

262

EXPERIENCES IN DESIGNING SOLVENTS FOR THE ENVIRONMENT  

EPA Science Inventory

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

263

Pneumatic conveying of pulverized solvent refined coal  

DOEpatents

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

Lennon, Dennis R. (Allentown, PA)

1984-11-06

264

Weak Values are Interference Phenomena  

E-print Network

Weak values arise experimentally as conditioned averages of weak (noisy) observable measurements that minimally disturb an initial quantum state, and also as dynamical variables for reduced quantum state evolution even in the absence of measurement. These averages can exceed the eigenvalue range of the observable ostensibly being estimated, which has prompted considerable debate regarding their interpretation. Classical conditioned averages of noisy signals only show such anomalies if the quantity being measured is also disturbed prior to conditioning. This fact has recently been rediscovered, along with the question whether anomalous weak values are merely classical disturbance effects. Here we carefully review the role of the weak value as both a conditioned observable estimation and a dynamical variable, and clarify why classical disturbance models will be insufficient to explain the weak value unless they can also simulate other quantum interference phenomena.

Justin Dressel

2015-02-26

265

Weak values as interference phenomena  

NASA Astrophysics Data System (ADS)

Weak values arise experimentally as conditioned averages of weak (noisy) observable measurements that minimally disturb an initial quantum state, and also as dynamical variables for reduced quantum state evolution even in the absence of measurement. These averages can exceed the eigenvalue range of the observable ostensibly being estimated, which has prompted considerable debate regarding their interpretation. Classical conditioned averages of noisy signals only show such anomalies if the quantity being measured is also disturbed prior to conditioning. This fact has recently been rediscovered, along with the question whether anomalous weak values are merely classical disturbance effects. Here we carefully review the role of the weak value as both a conditioned observable estimation and a dynamical variable, and clarify why classical disturbance models will be insufficient to explain the weak value unless they can also simulate other quantum interference phenomena.

Dressel, Justin

2015-03-01

266

Weak Separation and Plabic Graphs  

E-print Network

Leclerc and Zelevinsky described quasicommuting families of quantum minors in terms of a certain combinatorial condition, called weak separation. They conjectured that all maximal by inclusion weakly separated collections of minors have the same cardinality, and that they can be related to each other by a sequence of mutations. On the other hand, Postnikov studied total positivity on the Grassmannian. He described a stratification of the totally nonnegative Grassmannian into positroid strata, and constructed their parametrization using plabic graphs. In this paper we link the study of weak separation to plabeic graphs. We extend the notion of weak separation to positroids. We generalize the conjectures of Leclerc and Zelevinsky, and related ones of Scott, and prove them. We show that the maximal weakly separated collections in a positroid are in bijective correspondence with the plabic graphs. This correspondence allows us to use the combinatorial techniques of positroids and plabic graphs to prove the (gener...

Oh, Suho; Speyer, David E

2011-01-01

267

Variational transition state theory evaluation of the rate constant for proton transfer in a polar solvent  

SciTech Connect

Variational transition state theory (VTST) is used to calculate rate constants for a model proton transfer reaction in a polar solvent. We start from an explicit description of the reacting solute in a solvent, and we model the effects of solvation on the reaction dynamics by a generalized Langevin equation (GLE) for the solute. In this description, the effects of solvation on the reaction energetics are included in the potential of mean force, and dynamical, or nonequilibrium, solvation is included by solvent friction. The GLE solvation dynamics are approximated by a collection of harmonic oscillators that are linearly coupled to the coordinates of the reacting system. This approach is applied to a model developed by Azzouz and Borgis [J. Chem. Phys. 98, 7361 (1993)] to represent proton transfer in a phenol-amine complex in liquid methyl chloride. In particular, semiclassical VTST, including multidimensional tunneling contributions, is applied to this model with three explicit solute coordinates and a multioscillator GLE description of solvation to calculate rate constants. We compare our computed rate constants and H/D kinetic isotope effects to previous calculations using other approximate dynamical theories, including approaches based on one-dimensional models, molecular dynamics with quantum transitions, and path integrals. By examining a systematic sequence of 18 different sets of approximations, we clarify some of the factors (such as classical vibrations, harmonic approximations, quantum character of reaction-coordinate motion, and nonequilibrium solvation) that contribute to the different predictions of various approximation schemes in the literature.

Mcrae, Robin; Schenter, Gregory K.; Garrett, Bruce C.; Svetlicic, Zoran; Truhlar, Donald G.

2001-11-08

268

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

269

Toxic hepatitis in occupational exposure to solvents  

PubMed Central

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

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

2012-01-01

270

Composite weak bosons and structure of weak interactions  

SciTech Connect

A new approach to weak interactions is presented where possible similarities between weak and nuclear forces are exploited in a composite model of quarks and leptons. A new hypercolor dynamics, similar to quantum chromodynamics, but with a scale of order one TeV is postulated to act on the constituents of quarks and leptons and provide the binding mechanism. This leads to a composite picture of the W-bosons and provides an explanation of the origin of the Fermi constant. Understanding the large value of the weak mixing angle sin theta/sub W/ seems to impose a constraint on the electric charge structure of the constituents.

Mohapatra, R.N.

1983-01-01

271

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. 

272

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

273

General Coordinates Game  

NSDL National Science Digital Library

This interactive Java applet allows users to plot a "house" on a -10 by 10 coordinate plane. A "view" mode allows users to enter an ordered pair and move the house to that location. The "guess" mode randomly plots the house on the plane and the user must enter the ordered pair for its location. An optional scoring feature allows users to keep track of the number correct.

2005-01-01

274

Modeling the solubility of pharmaceuticals in pure solvents and solvent mixtures for drug process design.  

PubMed

The knowledge of the solubility of pharmaceuticals in pure solvents and solvent mixtures is crucial for designing the crystallization process of drug substances. The first step in finding optimal crystallization conditions is usually a solvent screening. Since experiments are very time consuming, a model which allows for solubility predictions in pure solvents and solvent mixtures based only on a small amount of experimental data is required. In this work, we investigated the applicability of the thermodynamic model perturbed-chain statistical associating fluid theory (PC-SAFT) to correlate and to predict the solubility of exemplary five typical drug substances and intermediates (paracetamol, ibuprofen, sulfadiazine, p-hydroxyphenylacetic acid, and p-aminophenylacetic acid) in pure solvents and solvent mixtures. PMID:19283772

Ruether, Feelly; Sadowski, Gabriele

2009-11-01

275

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

SciTech Connect

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

Fondeur, F; Samuel Fink, S

2006-03-07

276

Radical scavenging activities of extract and solvent-solvent partition fractions from Dendrobium Sonia “Red Bom” flower  

Microsoft Academic Search

Radical scavenging activities of extract and solvent-solvent partition fractions from the orchid flower, Dendrobium Sonia “Red Bom” were evaluated. Flower of Dendrobium Sonia “Red Bom” was extracted with acidified methanol. The residue was redissolved in water which was then subjected to solvent-solvent partition with organic solvents. Crude extract (CEDS) and three different fractions namely hexane layer (HXL), ethyl acetate layer

T. S. Shafazila; Pat M. Lee; Lee Kong Hung

2010-01-01

277

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

278

Experimental investigations of weak definite and weak indefinite noun phrases.  

PubMed

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

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

2013-08-01

279

Experimental investigations of weak definite and weak indefinite noun phrases  

PubMed Central

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

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

2013-01-01

280

International Space Exploration Coordination Group  

E-print Network

International Space Exploration Coordination Group The Global Exploration Roadmap September 2011, and stimulating technical and commercial innovation. As more nations undertake space exploration activities agencies participating in the International Space Exploration Coordination Group (ISECG) are developing

281

INTERNATIONAL SPACE EXPLORATION COORDINATION GROUP  

E-print Network

1 INTERNATIONAL SPACE EXPLORATION COORDINATION GROUP WORKPLAN Update following 3rd ISECG Meeting space exploration infrastructure standards facilitating interoperability through an international architecture working group. · Continue development of the INTERnational Space Exploration Coordination Tool

282

International Space Exploration Coordination Group  

E-print Network

International Space Exploration Coordination Group The Global Exploration Roadmap September 2011 participating in the International Space Exploration Coordination Group (ISECG) are developing the Global. Agencies agree that human space exploration will be most successful as an international endeavor because

283

Resisting Weakness of the Will  

PubMed Central

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

Levy, Neil

2012-01-01

284

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

285

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

286

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

287

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...

288

Improved Generalized Born Solvent Model Parameters for Protein Simulations  

PubMed Central

The generalized Born (GB) model is one of the fastest implicit solvent models and it has become widely adopted for Molecular Dynamics (MD) simulations. This speed comes with tradeoffs, and many reports in the literature have pointed out weaknesses with GB models. Because the quality of a GB model is heavily affected by empirical parameters used in calculating solvation energy, in this work we have refit these parameters for GB-Neck, a recently developed GB model, in order to improve the accuracy of both the solvation energy and effective radii calculations. The data sets used for fitting are significantly larger than those used in the past. Comparing to other pairwise GB models like GB-OBC and the original GB-Neck, the new GB model (GB-Neck2) has better agreement to Poisson-Boltzmann (PB) in terms of reproducing solvation energies for a variety of systems ranging from peptides to proteins. Secondary structure preferences are also in much better agreement with those obtained from explicit solvent MD simulations. We also obtain near-quantitative reproduction of experimental structure and thermal stability profiles for several model peptides with varying secondary structure motifs. Extension to non-protein systems will be explored in the future.

Nguyen, Hai; Roe, Daniel R.; Simmerling, Carlos

2013-01-01

289

Solvent fermentations of pulp streams and their constituents  

SciTech Connect

A number of industrial solvents, including C/sub 2/ to C/sub 5/ mono- and di-hydric alcohols and corresponding ketones, can be made by bacterial fermentation of pulp streams and their constituent carbohydrates. Most of these fermentations are reported to have been performed by members of the genus Clostridium, obligate gram positive anaerobic bacilli, although some, generally dihydric alcohol fermentations, are performed by Klebsiella. Solvents fermentations have been used historically since 1916, with periods of concentrated industrial development coinciding with major wars. Historically, the fermentation feedstocks have varied to include most of the common grains, vegetables, fruits, and nuts; however, the bacterial strains used for these fermentations are able to metabolize the materials found in pulping streams ranging from weak acid sulfite liquor to wood hydrolyzate to cellulose. It appears that these organisms will be likely to find use as fermentation agents for various wood and pulp streams with appropriate strain and bioprocess development. Methods for selecting and maintaining cultures are discussed.

Griffith, W.L.; Compere, A.L.

1984-01-01

290

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

291

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

292

Unusual effects of solvent polarity on capacitance for organic electrolytes in a nanoporous electrode.  

PubMed

The interplay between ions and solvent molecules inside the nanoporous electrodes of a supercapacitor has not been well understood but could be a fertile ground for new insights into the device's performance. By tuning the dipole moment of the solvent in an organic electrolyte, we find, from classical density functional theory calculations, pronounced oscillation of capacitance with the pore size for a moderately to weakly polar solvent. A quantitative analysis of the electric-double-layer (EDL) structure indicates that the capacitance oscillation shares a similar physical origin to that of an ionic liquid electrolyte: the oscillatory behavior arises from the formation of alternating layers of counterions and coions near strongly charged surfaces. More interestingly, we find that in the large-pore region, the capacitance versus the pore size has a volcano-shaped trend; in other words, there exists a solvent dipole moment that yields a maximal capacitance. These theoretical predictions can be validated with future experiments and highlight the great potential in tuning the organic solvent to achieve optimal performance of EDL capacitors. PMID:24733527

Jiang, De-en; Wu, Jianzhong

2014-05-21

293

Unusual effects of solvent polarity on capacitance for organic electrolytes in a nanoporous electrode  

NASA Astrophysics Data System (ADS)

The interplay between ions and solvent molecules inside the nanoporous electrodes of a supercapacitor has not been well understood but could be a fertile ground for new insights into the device's performance. By tuning the dipole moment of the solvent in an organic electrolyte, we find, from classical density functional theory calculations, pronounced oscillation of capacitance with the pore size for a moderately to weakly polar solvent. A quantitative analysis of the electric-double-layer (EDL) structure indicates that the capacitance oscillation shares a similar physical origin to that of an ionic liquid electrolyte: the oscillatory behavior arises from the formation of alternating layers of counterions and coions near strongly charged surfaces. More interestingly, we find that in the large-pore region, the capacitance versus the pore size has a volcano-shaped trend; in other words, there exists a solvent dipole moment that yields a maximal capacitance. These theoretical predictions can be validated with future experiments and highlight the great potential in tuning the organic solvent to achieve optimal performance of EDL capacitors.

Jiang, De-En; Wu, Jianzhong

2014-04-01

294

Effect of solvent polarity on nonradiative processes in xanthene dyes: rhodamine B in normal alcohols  

SciTech Connect

The fluorescence lifetime of rhodamine B in a series of normal alcohols (C/sub n/H/sub 2n-1/OH, n = 1-6) was measured as a function of temperature. The nonradiative rate constants were calculated from the fluorescence lifetimes and quantum yields. Activation energies were obtained from Arrhenius plots of the nonradiative rate constant. The variation of the nonradiative rate constant with solvent polarity and temperature was consistent with a photophysical mechanism that involves equilibrium between the planar and twisted configurations of the diethylamino groups on the xanthene ring of rhodamine B and internal conversion from the twisted configuration. The activation energy is equal to the free energy difference between the twisted and planar configurations. The solvent polarity dependence of the free energy difference and of the rate constant for internal conversion from the twisted configuration determines the variation of the nonradiative rate constant with solvent. When solvent polarity effects are taken into account by using the parameter E/sub T/(30), the nonradiative rate constant shows weak or no dependence on the solvent viscosity.

Casey, K.G.; Quitevis, E.L.

1988-11-17

295

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

296

Management Issues in Service Coordination  

Microsoft Academic Search

Despite the growing popularity of service coordination in senior housing, the literature has yet to discuss the management issues that arise when professionals from housing and social services work together. This article discusses the problems and tensions that arise when service coordination is introduced into senior housing. Identification of issues\\/tensions is based upon experiences with the Resident Services Coordinator Program,

Nancy W. Sheehan

1996-01-01

297

SOL EXTERNAL COORDINATOR Diversity Development  

E-print Network

1 SOL EXTERNAL COORDINATOR Diversity Development OREGON STATE UNIVERSITY TERMS OF EMPLOYMENT & POSITION DESCRIPTION 2011-2012 The Sol External Coordinator works with collaborators to create programs://oregonstate.edu/pridecenter/sol/ The External Coordinator must be committed to the development of an inclusive community in the Cultural Centers

Escher, Christine

298

GEAR Tech-21 Geographic Coordinates  

E-print Network

GEAR Tech-21 Geographic Coordinates Throughout the activity, look for and record the definitions and two others on the grid below: Important Terms #12;GEAR Tech-21 Geographic Coordinates How Far Are They: Miles: #12;GEAR Tech-21 Geographic Coordinates Try It! Use the Satellites page on your handheld GPS

Farritor, Shane

299

Multipole Structure and Coordinate Systems  

ERIC Educational Resources Information Center

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

Burko, Lior M.

2007-01-01

300

On deriving nonreflecting boundary conditions in generalized curvilinear coordinates  

E-print Network

In this work, nonreflecting boundary conditions in generalized three-dimensional curvilinear coordinates are derived, relying on the original analysis that was done in Cartesian two-dimensional coordinates by Giles (AIAA Journal, 28.12, 2050-2058, 1990). A thorough Fourier analysis of the linearized Euler equation is performed to determine the eigenvalues and the eigenvectors that are then used to derive the appropriate inflow and outflow boundary conditions. The analysis lacks rigorous proof of the well-posedness in the general case, which is open to investigation (a weak assumption is introduced here to complete the boundary conditions). The boundary conditions derived here are not tested on specific applications.

Adrian Sescu

2015-01-20

301

Weak interactions and presupernova evolution  

SciTech Connect

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

Aufderheide, M.B. (Lawrence Livermore National Lab., CA (USA) State Univ. of New York (USA). Dept. of Physics)

1991-02-19

302

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

303

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

304

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

305

TRUEX process solvent cleanup with solid sorbents  

SciTech Connect

Solid sorbents, alumina, silica gel, and Amberlyst A-26 have been tested for the cleanup of degraded TRUEX-NPH solvent. A sodium carbonate scrub alone does not completely remove acidic degradation products from highly degraded solvent and cannot restore the stripping performance of the solvent. By following the carbonate scrub with either neutral alumina or Amberlyst A-26 anion exchange resin, the performance of the TRUEX-NPH is substantially restored. The degraded TRUEX-NPH was characterized before and after treatment by supercritical fluid chromatography. Its performance was evaluated by americium distribution ratios, phase-separation times, and lauric acid distribution coefficients. 17 refs., 2 figs., 5 tabs.

Tse, Pui-Kwan; Reichley-Yinger, L.; Vandegrift, G.F.

1989-01-01

306

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.

2013-08-20

307

Exploring Hamiltonian dielectric solvent molecular dynamics  

NASA Astrophysics Data System (ADS)

Hamiltonian dielectric solvent (HADES) is a recent method [7,25], which enables Hamiltonian molecular dynamics (MD) simulations of peptides and proteins in dielectric continua. Sample simulations of an ?-helical decapeptide with and without explicit solvent demonstrate the high efficiency of HADES-MD. Addressing the folding of this peptide by replica exchange MD we study the properties of HADES by comparing melting curves, secondary structure motifs and salt bridges with explicit solvent results. Despite the unoptimized ad hoc parametrization of HADES, calculated reaction field energies correlate well with numerical grid solutions of the dielectric Poisson equation.

Bauer, Sebastian; Tavan, Paul; Mathias, Gerald

2014-09-01

308

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

309

Interaction of organic solvents with protein structures at protein-solvent interface.  

PubMed

The effect of non-denaturing concentrations of three different organic solvents, formamide, acetone and isopropanol, on the structure of haloalkane dehalogenases DhaA, LinB, and DbjA at the protein-solvent interface was studied using molecular dynamics simulations. Analysis of B-factors revealed that the presence of a given organic solvent mainly affects the dynamical behavior of the specificity-determining cap domain, with the exception of DbjA in acetone. Orientation of organic solvent molecules on the protein surface during the simulations was clearly dependent on their interaction with hydrophobic or hydrophilic surface patches, and the simulations suggest that the behavior of studied organic solvents in the vicinity of hyrophobic patches on the surface is similar to the air/water interface. DbjA was the only dimeric enzyme among studied haloalkane dehalogenases and provided an opportunity to explore effects of organic solvents on the quaternary structure. Penetration and trapping of organic solvents in the network of interactions between both monomers depends on the physico-chemical properties of the organic solvents. Consequently, both monomers of this enzyme oscillate differently in different organic solvents. With the exception of LinB in acetone, the structures of studied enzymes were stabilized in water-miscible organic solvents. PMID:22760789

Khabiri, Morteza; Minofar, Babak; Brezovský, Jan; Damborský, Ji?í; Ettrich, Rudiger

2013-11-01

310

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

311

Coordination of temporal plans in dynamic environments  

E-print Network

Coordination) Coordination before planning Social Laws [Shoham 1995], [Buzzing 2006] Coordination during Plan Merging [Tsamardinos et al. 2000] Merging Hierarchical Plans [von Martial 1992] Synchronization

312

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

313

Solvent-type-dependent polymorphism and charge transport in a long fused-ring organic semiconductor  

NASA Astrophysics Data System (ADS)

Crystalline polymorphism of organic semiconductors is among the critical factors in determining the structure and properties of the resultant organic electronic devices. Herein we report for the first time a solvent-type-dependent polymorphism of a long fused-ring organic semiconductor and its crucial effects on charge transport. A new polymorph of 5,11-bis(triethylsilylethynyl)anthradithiophene (TES ADT) is obtained using solvent-assisted crystallization, and the crystalline polymorphism of TES ADT thin films is correlated with their measured hole mobilities. The best-performing organic thin film transistors of the two TES ADT polymorphs show subthreshold slopes close to 1 V dec-1, and threshold voltages close to zero, indicating that the density of traps at the semiconductor-dielectric interface is negligible in these devices and the observed up to 10-fold differences in hole mobilities of devices fabricated with different solvents are largely resultant from the presence of two TES ADT polymorphs. Moreover, our results suggest that the best-performing TES ADT devices reported in the literature correspond to the new polymorph identified in this study, which involves crystallization from a weakly polar solvent (such as toluene and chloroform).Crystalline polymorphism of organic semiconductors is among the critical factors in determining the structure and properties of the resultant organic electronic devices. Herein we report for the first time a solvent-type-dependent polymorphism of a long fused-ring organic semiconductor and its crucial effects on charge transport. A new polymorph of 5,11-bis(triethylsilylethynyl)anthradithiophene (TES ADT) is obtained using solvent-assisted crystallization, and the crystalline polymorphism of TES ADT thin films is correlated with their measured hole mobilities. The best-performing organic thin film transistors of the two TES ADT polymorphs show subthreshold slopes close to 1 V dec-1, and threshold voltages close to zero, indicating that the density of traps at the semiconductor-dielectric interface is negligible in these devices and the observed up to 10-fold differences in hole mobilities of devices fabricated with different solvents are largely resultant from the presence of two TES ADT polymorphs. Moreover, our results suggest that the best-performing TES ADT devices reported in the literature correspond to the new polymorph identified in this study, which involves crystallization from a weakly polar solvent (such as toluene and chloroform). Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr04341j

Chen, Jihua; Shao, Ming; Xiao, Kai; Rondinone, Adam J.; Loo, Yueh-Lin; Kent, Paul R. C.; Sumpter, Bobby G.; Li, Dawen; Keum, Jong K.; Diemer, Peter J.; Anthony, John E.; Jurchescu, Oana D.; Huang, Jingsong

2013-12-01

314

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

315

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

2015-02-16

316

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...

317

Innovative Technologies for Chlorinated Solvent Remediation  

NASA Astrophysics Data System (ADS)

The following sections are included: * INTRODUCTION * TRADITIONAL REMEDIATION TECHNOLOGIES (1980s) * RESEARCH AND DEVELOPMENT OF INNOVATIVE REMEDIATION TECHNOLOGIES (1990s-2000s) * CURRENT TRENDS IN CHLORINATED SOLVENT REMEDIATION (2010s) * CLOSING THOUGHTS * REFERENCES

Pennell, Kurt D.; Cápiro, Natalie L.

2014-07-01

318

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

1993-01-01

319

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

320

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...

321

Accelerated solvent extraction of petroleum contaminated sediments  

E-print Network

Attempts have been made in recent years to find acceptable alternatives to classical soxhlet extraction of petroleum contaminated sediments. One such method that is very promising is accelerated solvent extraction also referred to as high pressure...

Bauguss, Jeffery Lynn

1997-01-01

322

Deasphalted oil: A natural asphaltene solvent  

SciTech Connect

Asphaltene deposition in the near-wellbore region can block pore throats, change wettability characteristics and relative-permeability relationships, and therefore, reduce oil production. Conventional aromatic solvents (e.g., toluene and xylene) alone or in combination with various dispersants are used to remove asphaltene damage from the near-wellbore region. However, these aromatic solvents are expensive and are not environmentally friendly. The objective of this work was to systematically evaluate the asphaltene-solvating power of various nonconventional solvents, including deasphalted oil, using a light-scattering technique. Experimental results suggest that deasphalted oil is a strong asphaltene solvent presumably because of its native resin and aromatic contents. Addition of asphaltene dispersants also increases the solubilizing power of the deasphalted oil. Furthermore, various refinery and heavy oil upgrader streams show strong ability to solubilize asphaltenes.

Jamaluddin, A.K.M. [Noranda Technology Centre, Pointe Claire, Quebec (Canada); Nazarko, T.W.; Sills, S. [Norcen Energy Resources Ltd., Calgary, Alberta (Canada); Fuhr, B.J. [Alberta Research Council, Edmonton, Alberta (Canada)

1996-08-01

323

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

324

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

325

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

326

Series of solvent-induced single-crystal to single-crystal transformations with different sizes of solvent molecules.  

PubMed

A highly stable soft porous coordination polymer (PCP), namely [Cu3(TP)4(N3)2(DMF)2]·2H2O·2DMF (1), has been synthesized via an in situ synthesis of 4-tetrazole pyridine (TP) under solvothermal conditions (DMF = N,N'-dimethylformamide). Remarkably, the solvent molecules in 1 can be respectively exchanged with cyclohexane (C6H12), cyclopentane (C5H10), decahydronaphthalene (C10H18), 1,4-dioxane (C4H8O2), and tetrahydropyrane (C5H10O) in single-crystal to single-crystal (SCSC) manners to yield [Cu3(TP)4(N3)2(DMF)2]·3C6H12 (1a), [Cu3(TP)4(N3)2(DMF)2]·2C5H10 (1b), [Cu3(TP)4(N3)2(DMF)2]·H2O·C10H18 (1c), [Cu3(TP)4(N3)2(DMF)2]·C4H8O2 (1d), [Cu3(TP)4(N3)2]·3C4H8O2 (1e), and [Cu3(TP)4(N3)2]·2H2O·C5H10O (1f). Further, the occluded cyclohexane molecules in 1a can be removed by heating to give its porous guest-free form [Cu3(TP)4(N3)2(DMF)2] (1g). Particularly, in water, 1 can lose its coordinated N3(-) anions to generate [Cu(TP)2(H2O)4]·4H2O (1h). More interestingly, the soft PCP (1) demonstrates the guest selectivity for the cycloalkane solvents, namely cyclohexane, cyclopentane, and decahydronaphthalene, in SCSC manners for the first time, attributed to the synergy effect between the size and geometry of the solvent and the shape of the framework cavity. Moreover, the desolvated samples of 1e show the highly selective gas adsorption of CO2 over N2, indicating its potential application in the separation of the CO2/N2 mixture. PMID:24983509

He, Yuan-Chun; Yang, Jin; Liu, Ying-Ying; Ma, Jian-Fang

2014-07-21

327

Weakly coordinating anions M(OTeFâ)â⁻ (M = Nb, Sb) and M(OTeFâ)â²⁻ (M = Ti, Zr, Hf): Two-step synthesis, characterization, stability, and use in the isolation of the dihaloalkane complex cations Ag(CHâClâ)â{sup +}, Ag(CHâBrâ)â{sup +}, and catena-poly[Ag(1,2-CâHâBrâ)â-μ-(1,2-CâHâBrâ)-Br:Brâ²]{sup +}  

Microsoft Academic Search

Chemical preparation and reactions of silver salts of M(OTeFâ)â⁻ (M = Nb, Sb), and Mâ²(OTeFâ)â⁻ (Mâ² = Ti, Zr, Hf) were reported. The silver salts were converted to CPhâ{sup +} or N(n-Bu)â{sup +} salts. AgâTi(OTeFâ)â, AgNb(OTeFâ)â, and AgSb(OTeFâ)â were recrystallized in dihaloalkane solvents yielding crystals containing solvent molecules which were subsequently characterized by X-ray crystallography. Reactivity of the anions toward

D. M. Van Seggen; P. K. Hurlburt; O. P. Anderson; S. H. Strauss

1995-01-01

328

Method of stripping metals from organic solvents  

DOEpatents

A new method to strip metals from organic solvents in a manner that allows for the recycle of the stripping agent. The method utilizes carbonate solutions of organic amines with complexants, in low concentrations, to strip metals from organic solvents. The method allows for the distillation and reuse of organic amines. The concentrated metal/complexant fraction from distillation is more amenable to immobilization than solutions resulting from current practice.

Todd, Terry A. (Aberdeen, ID); Law, Jack D. (Pocatello, ID); Herbst, R. Scott (Idaho Falls, ID); Romanovskiy, Valeriy N. (St. Petersburg, RU); Smirnov, Igor V. (St.-Petersburg, RU); Babain, Vasily A. (St-Petersburg, RU); Esimantovski, Vyatcheslav M. (St-Petersburg, RU)

2009-02-24

329

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

Microsoft Academic Search

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

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

2006-01-01

330

Micro-solvent cluster extraction using aqueous mixed solvents of ionic liquid.  

PubMed

Organic compounds (2-naphthol, phenol, 4-chlorophenol, 4-nitrophenol, and 1,3,5-naphthalenetrisulfonic acid) were sufficiently separated from mixtures during flow in a fused silica capillary tube (50 microm in i.d. and 45 cm in length) with an aqueous mixed solvent of an ionic liquid, 1-butyl-3-methylimidazolium chloride (BMIM(+)Cl(-)), without a specific separation column. The method is based on micro-solvent cluster formation in aqueous mixed solvents of ionic liquid and preferential solvation of solvent clusters to analytes. The measurement of large angle X-ray scattering (LAXS) of aqueous mixed solvents with an ionic liquid of tetrafluoroborate (BMIM(+)BF(4)(-)) indicated the formation of micro-solvent clusters of water and ionic liquid in the mixed solvent. A neutral polymer (polyvinylpyrrolidone, PVP) enhanced the separation. Polarized or ionic molecules eluted slowly. The theoretical plate numbers were 6320, 22907, 63645, and 37184 for 2-naphthol, phenol, 4-chlorophenol, and 4-nitrophenol, respectively, under the conditions of 1.0 M of BMIM(+)Cl(-) and 0.1 M of PVP; the flow rate was 1 microL min(-1). The separation mechanism is discussed from the viewpoint of the partition of analytes between micro-solvent clusters of water and organic solvent molecules. PMID:18845880

Charoenraks, Thiraporn; Tabata, Masaaki; Fujii, Kenta

2008-10-01

331

CHEMICAL STABILITY OF POLYPHENYLENE SULFIDE IN THE NEXT GENERATION SOLVENT FOR CAUSTIC-SIDE SOLVENT EXTRACTION  

SciTech Connect

The Office of Waste Processing, within the Office of Technology Innovation and Development, is funding the development of an enhanced solvent for deployment at the Savannah River Site for removal of cesium from High Level Waste. For simplicity, this solvent is referred to as the Next Generation Solvent (NGS). The technical effort is collaboration between Oak Ridge National Laboratory (ORNL), Savannah River National Laboratory (SRNL), and Argonne National Laboratory. The initial deployment target envisioned for the technology was within the Modular Caustic-Side Solvent Extraction Unit (MCU). Deployment of a new chemical within an existing facility requires verification that the chemical components are compatible with the installed equipment. In the instance of a new organic solvent, the primary focus is on compatibility of the solvent with polyphenylene sulfide (PPS), the polymer used in the coalescers within MCU. This report provides the data from exposing PPS polymer to NGS. The test was conducted over a three month period. PPS is remarkably stable in the presence of the next generation solvent. Testing showed no indication of swelling or significant leaching. Preferential sorption of the Modifier on PPS was observed but the same behavior occurs with the baseline solvent. Therefore, PPS coalescers exposed to the NGS are expected to perform comparably to those in contact with the baseline solvent.

Fondeur, F.; Fink, S.

2011-12-08

332

Weak Selection and Protein Evolution  

PubMed Central

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

Akashi, Hiroshi; Osada, Naoki; Ohta, Tomoko

2012-01-01

333

Highly enantioselective hydrogenation of alpha-dehydroamino esters and itaconates with triphosphorous bidentate ligands and the unprecedented solvent effect thereof.  

PubMed

An X-ray diffraction experiment revealed an interesting triphosphorous bidentate coordination in a Pd(II) complex of a phosphine-phosphoramidite ligand 1, which showed excellent enantioselectivity (up to 99.4% ee) in Rh-catalyzed hydrogenation of alpha-dehydroamino esters in acetone. A dramatic solvent effect was found in the hydrogenation of itaconates, which induces opposite chiralities of the product with the same catalytic system by the use of different solvents (e.g., 99.6% ee (R) in TFE vs 71.2% ee (S) in methyl ethyl ketone). PMID:17253827

Zhang, Weicheng; Zhang, Xumu

2007-02-01

334

?-Rich ?(2)P-Heterocycles: Bent ?(1)-P- and ?(2)-P-Coordinated 1,3-Benzazaphosphole Copper(I) Halide Complexes.  

PubMed

The reaction of 1-neopentyl-1,3-benzazaphosphole 1 with CuCl, CuBr, or Cu(SMe2)Br in THF at room temperature provides sparingly soluble [Cu7(?(2)-L6)(?(2)-X7)](+)[CuX2](-) cluster complexes 2a,b (L indicates coordinated 1, a X = Cl, b X = Br), with loosely bound THF, in high yields. The conversions proceed via transient THF-soluble labile [(L2CuX)2] complexes. Separation before complete conversion, combined with suitable conditions for crystallization, allowed these intermediates to be trapped. Depending on the reactant ratios, crystals of the clusters or of dimeric L2CuX complexes were formed. The crystal structure analyses of 2a·4THF and the dimers 3b [{Cu(?(1)-L)2(?(2)-Br)}2], 4b [{Cu(?(2)-L)(?(1)-L)(?Br)}2], 5a·2MeOH, and 5b·2MeOH [{Cu(?(2)-L)(?(1)-L)(?X···HOMe)}2] generally display ?(2)-P- and/or tilted ?(1)-P-coordination, contrasting with the preference for the ?(1)-P in-plane coordination mode of phosphinine ligands in their copper(I) halide complexes. DFT studies of geometry-optimized monomers LCuBr, L(CuBr)2, L2CuBr, and the dimers 3b and 4b, calculated at the ?B97xD/cc-PVDZ level, suggest that weak competing interactions with the solvent THF and the entropy factor of the dimerization result in lability and a subtle balance between the different complexes in solution, whereas the particular coordination observed in the crystals is attributable to conservation of the delocalized ?-system in the ligand. The HOMO of 4b is composed of Cu d orbitals and the ?-type HOMO of the bridging ligand. Interestingly, despite the rather short Cu···Cu interatomic separation (2.726 ?), no bond critical point could be located in 4b, indicating the absence of weak cuprophilic interactions in this compound. PMID:25661753

Ghalib, Mohammed; Jones, Peter G; Schulzke, Carola; Sziebert, Dénes; Nyulászi, László; Heinicke, Joachim W

2015-03-01

335

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.

336

Network Coordinator Report  

NASA Technical Reports Server (NTRS)

This report includes an assessment of the network performance in terms of lost observing time for the 2012 calendar year. Overall, the observing time loss was about 12.3%, which is in-line with previous years. A table of relative incidence of problems with various subsystems is presented. The most significant identified causes of loss were electronics rack problems (accounting for about 21.8% of losses), antenna reliability (18.1%), RFI (11.8%), and receiver problems (11.7%). About 14.2% of the losses occurred for unknown reasons. New antennas are under development in the USA, Germany, and Spain. There are plans for new telescopes in Norway and Sweden. Other activities of the Network Coordinator are summarized.

Himwich, Ed; Strand, Richard

2013-01-01

337

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

338

Scale-up of recovery process for waste solvents  

NASA Astrophysics Data System (ADS)

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.

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

1991-02-01

339

Tackling Water Shortage by using Solvent Extraction for Efficient Desalination  

Microsoft Academic Search

In this paper we analyze solvent extraction based desalination systems which are energy efficient and less expensive to operate. Solvent extraction is widely used in the industry to extract the material of interest from a solution by using a solvent. However, currently no solvent extraction based desalination plants are commercially available anywhere in the world. In this work, a systems

Kary Thanapalan; Vivek Dua

2010-01-01

340

29 CFR 1915.32 - Toxic cleaning solvents.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 2010-07-01 false Toxic cleaning solvents. 1915.32 Section 1915...and Preservation § 1915.32 Toxic cleaning solvents. (a) When toxic solvents...exposed to these solvents. (1) The cleaning operation shall be completely...

2010-07-01

341

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

342

Effects of solvent polarity and solvent viscosity on the fluorescent properties of molecular rotors  

E-print Network

Effects of solvent polarity and solvent viscosity on the fluorescent properties of molecular rotors attention, although changed cytoplasmic viscosity is sus- pected to be involved in, for example, smoking and lung macrophage activation [6,7]. On a more macroscopic scale, viscosity changes in blood plasma [8

Theodorakis, Emmanuel

343

40 CFR Table 4 to Subpart Oooo 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 OOOO 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

344

40 CFR Table 4 to Subpart Oooo 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 OOOO 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

345

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

346

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

347

Air-assisted solvent extraction: towards a novel extraction process  

Microsoft Academic Search

The air-assisted solvent extraction (AASX) concept uses a solvent-coated bubble to contact the organic and aqueous phases. Compared to conventional solvent extraction, a high contact area can be created using less solvent and the natural buoyancy provided by the air core promotes phase separation. A method of producing coated bubbles exploiting foaming properties of kerosene-based solvent is introduced. Coating thickness

H. M. Tarkan; J. A. Finch

2005-01-01

348

Motor and coordinationMotor and coordination phenotypesphenotypes  

E-print Network

.htm Normal horizontal swimming Abnormal vertical swimming Kalueff et al., 2006 #12;Motor skills tests · DrugMotor and coordinationMotor and coordination phenotypesphenotypes 1st ISBS Summer School1st ISBS;Assessing motor phenotypes · SHIRPA battery: a widely-accepted neurological battery involving a three- stage

Kalueff, Allan V.

349

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

350

Solvent gating of intramolecular electron transfer  

SciTech Connect

The rates for ionic photodissociation of malachite green leucocyanide to form cyanide ion and a malachite green carbonium ion were measured as a function of solvent and temperature. The observed rates in mixtures of polar and nonpolar solvents all had an activation energy of about 1 kcal/mol for a wide range of dielectric constants. This dissociative intramolecular electron transfer (DIET) is unusual because it is the first example where solvent configurational entropy changes are required to enable a large amplitude molecular distortion leading to a nonadiabatic electron transfer and ionic dissociation. This solvent gated intramolecular electron-transfer mechanism is supported by analysis of the preexponential and activation energy trends in dipolar aprotic solven mixtures and alcohol solvents. The large amplitude motion is not separately measurable due to the slow gating rates, but viscosity effects on both the preexponential and the activation energy are analyzed to demonstrate consistency with a barrierless diffusion model having a structural dependence on electron-transfer rate. The rate has an inverse dependence on viscosity raised to the 0.53 power. 36 refs., 6 figs., 4 tabs.

Miller, R.M. (California State Univ., Chico, CA (United States)); Spears, K.G.; Gong, J.H.; Wach, M. (Northwestern Univ., Evanston, IL (United States))

1994-02-03

351

Non-aqueous cleaning solvent substitution  

NASA Technical Reports Server (NTRS)

A variety of environmental, safety, and health concerns exist over use of chlorinated and fluorinated cleaning solvents. Sandia National Laboratories, Lawrence Livermore National Laboratories, and the Kansas City Division of AlliedSignal have combined efforts to focus on finding alternative cleaning solvents and processes which are effective, environmentally safe, and compliant with local, state, and federal regulations. An alternative solvent has been identified, qualified, and implemented into production of complex electronic assemblies, where aqueous and semi-aqueous cleaning processes are not allowed. Extensive compatibility studies were performed with components, piece-parts, and materials. Electrical testing and accelerated aging were used to screen for detrimental, long-term effects. A terpene, d-limonene, was selected as the solvent of choice, and it was found to be compatible with the components and materials tested. A brief history of the overall project will be presented, along with representative cleaning efficiency results, compatibility results, and residual solvent data. The electronics industry is constantly searching for proven methods and environmentally-safe materials to use in manufacturing processes. The information in this presentation will provide another option to consider on future projects for applications requiring high levels of quality, reliability, and cleanliness from non-aqueous cleaning processes.

Meier, Gerald J.

1994-01-01

352

Cosmology with weak lensing surveys.  

PubMed

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

Munshi, Dipak; Valageas, Patrick

2005-12-15

353

Solvent and temperature effects on the reduction and amination reactions of electrophiles by lithium dialkylaminoborohydrides.  

PubMed

The influence of temperature and solvent effects on the reduction and amination mechanisms of iodomethane by lithium N,N-diisopropylaminoborohydride (iPr-LAB) was examined in varying concentrations of THF and dioxane. The reactions of benzyl chloride and trimethylsilyl chloride with iPr-LAB in THF were also studied. The amination of iodomethane is favored over reduction at low and room temperatures in pure THF and with increasing the amount of dioxane in THF. At higher temperatures, the reduction reaction appears to compete with the amination. In dioxane solvent, however, iodomethane yields exclusively the amination product regardless of temperature. On the other hand, reduction by iPr-LAB to the aminoborane is the only product observed in THF when benzyl chloride and trimethylsilyl chloride are used. To understand the solvent effects on the product distribution, ab initio and density functional theory (DFT) calculations were used to examine the mechanisms of reduction and amination of chloromethane and bromomethane by lithium dimethylaminoborohydride (LAB) in THF and dioxane. The results of these calculations show that the relative reaction barrier heights are significantly affected by the nature of the coordinated solvent molecule and thus lend support to the experimental observations. PMID:17253818

Pasumansky, Lubov; Collins, Christopher J; Pratt, Lawrence M; Nguyên, Ngân Van; Ramachandran, B; Singaram, Bakthan

2007-02-01

354

Solvent effects on the structures and magnetic properties of two doubly interpenetrated metal-organic frameworks.  

PubMed

Two doubly interpenetrated coordination polymers [Co2(BDC)2(bpt)2]·nSolvent based on dimeric secondary building units and crystallizing with distinct solvent molecules (-H2O and -MeOH for nSolvent = 2H2O and MeOH·H2O, respectively) were obtained by employing 1,4-benzenedicarboxylate (BDC) and 1H-3,5-bis(4-pyridyl)-1,2,4-triazole) (bpt) as linkers. The structures consist of a square grid of dimers bridged by BDC and pillared by bpt. Thermogravimetry and PXRD indicate that the frameworks are stable and are retained up to 400 °C, but the structures are modified irreversibly. -H2O, high-symmetry Pna21, exhibits antiferromagnetic coupling within the dimer, while -MeOH, low-symmetry P21/n, exhibits ferromagnetic coupling. Upon desolvation, the -de and -de couplings are antiferromagnetic but reduced. Subsequent resolvation to -H2O and -MeOH resulted in a slight increase of the antiferromagnetic coupling without attaining the virgin states. The interesting difference of magnetic properties between -H2O and -MeOH, the solvated/desolvated phases, particularly at low temperature, indicates that there is a prominent solvent effect. PMID:25758296

Huang, Fu-Ping; Yang, Cheng; Li, Hai-Ye; Yao, Peng-Fei; Qin, Xiao-Huan; Yan, Shi-Ping; Kurmoo, Mohamedally

2015-03-24

355

Investigation of aggregation in solvent extraction of lanthanides by acidic extractants (organophosphorus and naphthenic acid)  

USGS Publications Warehouse

Three acidic extractants (I) di(2-ethylhexyl) phosphoric acid (HDEHP), (II) 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester (HEHPEHE) and (III) naphthenic acid were employed in preparing the samples for the characterization of the coordination structure of lanthanide-extractant complexes and the physicochemical nature of aggregates formed in the organic diluent of the solvent extraction systems. Photo correlation spectroscopy (PCS) results on the aggregates formed by the partially saponified HDEHP in n-heptane showed that the hydrodynamic radius of the aggregates was comparable to the molecular dimensions of HDEHP. The addition of 2-octanol into the diluent, by which the mixed solvent was formed, increased the dimensions of the corresponding aggregates. Aggregates formed from the lanthanide ions and HDEHP in the organic phase of the extraction systems were found very unstable. In the case of naphthenic acid, PCS data showed the formation of w/o microemulsion from the saponified naphthenic acid in the mixed solvent. The extraction of lanthanides by the saponified naphthenic acid in the mixed solvent under the given experimental conditions was a process of destruction of the w/o microemulsion. A possible mechanism of the breakdown of the w/o microemulsion droplets is discussed.

Zhou, N.; Wu, J.; Yu, Z.; Neuman, R.D.; Wang, D.; Xu, G.

1997-01-01

356

[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

357

Modeling organic solvents permeation through protective gloves.  

PubMed

Several researchers have studied the diffusion of organic solvents through chemical protective gloves and have estimated the diffusion coefficients by using various models. In this study, permeation experiments of benzene, toluene, and styrene through nitrile and Neoprene gloves were conducted using the ASTM F-739 standard test method. The diffusion coefficients were estimated using several models from the literature. Using a one-dimensional diffusion equation based on Fick's second law and the estimated diffusion coefficients, the permeation concentrations were simulated and compared with the experimental results. The modeling results indicated that the solubility of the solvent in the glove materials obtained by immersion tests was not an appropriate boundary condition for organic solvent permeation through the polymer gloves. The modeling work of this study will assist industrial hygienists to assess exposure of chemicals to workers through the chemical protective gloves. PMID:15204879

Chao, Keh-Ping; Wang, Ven-Shing; Lee, Pak-Hing

2004-02-01

358

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

359

Simple Model of Membrane Proteins Including Solvent  

E-print Network

We report a numerical simulation for the phase diagram of a simple two dimensional model, similar to one proposed by Noro and Frenkel [J. Chem. Phys. \\textbf{114}, 2477 (2001)] for membrane proteins, but one that includes the role of the solvent. We first use Gibbs ensemble Monte Caro simulations to determine the phase behavior of particles interacting via a square-well potential in two dimensions for various values of the interaction range. A phenomenological model for the solute-solvent interactions is then studied to understand how the fluid-fluid coexistence curve is modified by solute-solvent interactions. It is shown that such a model can yield systems with liquid-liquid phase separation curves that have both upper and lower critical points, as well as closed loop phase diagrams, as is the case with the corresponding three dimensional model.

D. L. Pagan; A. Shiryayev; T. P. Connor; J. D. Gunton

2006-03-04

360

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

361

POSITION DESCRIPTION Americorps Graduate Coordinator  

E-print Network

academic engagement), Healthy Futures (patient preventative/primary health care), and Capacity Building (volunteer management/training/recruitment via organizational development). The AmeriCorps Coordinator at CSU) Serve as a liaison with CSU college/department internship coordinators; assist in the development

Rutledge, Steven

362

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

363

Coordinate-Free Rotation Operator.  

ERIC Educational Resources Information Center

Suggests the use of a coordinate-free rotation operator for the teaching of rotations in Euclidean three space because of its twofold didactic advantage. Illustrates the potentialities of the coordinate-free rotation operator approach by a number of examples. (Author/GA)

Leubner, C.

1979-01-01

364

Pathwise Coordinate Optimization Jerome Friedman  

E-print Network

competitive with the well known LARS (or homotopy) procedure in large lasso problems, and that it can on this paper. In this paper we show that coordinate descent is very competitive with the well known LARS (or performance on some image smoothing problems. A key point here: coordinate descent works so well in the class

365

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

366

Newtonian and relativistic emission coordinates  

SciTech Connect

Emission coordinates are those generated by positioning systems. Positioning systems are physical systems constituted by four emitters broadcasting their respective times by means of sound or light signals. We analyze the incidence of the space-time causal structure on the construction of emission coordinates. The Newtonian case of four emitters at rest is analyzed and contrasted with the corresponding situation in special relativity.

Coll, Bartolome; Ferrando, Joan Josep; Morales-Lladosa, Juan Antonio [Departament d'Astronomia i Astrofisica, Universitat de Valencia, 46100 Burjassot, Valencia (Spain)

2009-09-15

367

What Happened to Service Coordination?  

ERIC Educational Resources Information Center

Comments on an article by Dunst and Bruder. Service coordination was supposed to be one of the major jewels in the legislative crown for young children with disabilities and their families. The authors have cast their experienced eyes on the heart of the matter, which is the models of service coordination that sprang to life almost immediately…

McWilliam, R. A.

2006-01-01

368

Distributed Coordination of First Responders  

Microsoft Academic Search

In a disaster scenario, first responders must be able to perform multiple functions in a coordinated way. At all levels of the task - from integrating heterogeneous systems to addressing response tasks and allocating resources - responders must be able to make decisions in a globally optimal fashion. Automated coordination mechanisms can help, but they still face several challenges that

Joseph B. Kopena; Evan A. Sultanik; Robert N. Lass; Duc N. Nguyen; Christopher J. Dugan; Pragnesh Jay Modi; William C. Regli

2008-01-01

369

Graphing and the Coordinate Plane  

NSDL National Science Digital Library

This lesson is designed to introduce students to graphing coordinates and lines in the Cartesian coordinate plane. This lesson provides links to discussions and activities related to graphing as well as suggested ways to integrate them into the lesson. Finally, the lesson provides links to follow-up lessons designed for use in succession with the current one.

2011-05-24

370

Coordinating Information for Texas Educators.  

ERIC Educational Resources Information Center

"Coordinating Information for Texas Educators" (CITE) is a project of the Texas Education Agency designed to develop and coordinate a comprehensive communication program for elementary and secondary schools and to include an adequate resource base and linkage system. Project CITE was designed by Region XIX Education Service Center to develop a…

Mancill, James T.

371

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

372

Successful 'Green' Solvent Found For Problematic Chemicals  

NSDL National Science Digital Library

This week's In The News highlights the discovery of a new process that could separate problematic chemicals from ionic liquids. In industry, chemical reactions are performed in toxic organic solvents and some can form carbon dioxide and other greenhouse gases. Specifically, the vapor pressure of these organic solvents is hazardous because these "solvents evaporate easily into the air." The effects of such a reaction are that factory workers may inhale them and "the solvents add to damage of the earth's atmosphere, because organic solvents eventually will oxidize and create carbon dioxide, a greenhouse gas with potential impact on global warming". Published in the May 6, 1999 issue of Nature, scientists Joan Brennecke, Eric Beckman and other team members discuss how two "benign compounds together can perform certain chemical separations now done only by noxious organics." In the process discussed in Nature these scientists enforced supercritical (high pressure that causes liquid and gas to combine into one fluid phase) carbon dioxide into a solution of naphthalene (an organic chemical) dissolved in an ionic liquid (liquid salts at room temperature made of organic cations and inorganic anions). This pulled the naphthalene out with it while leaving behind the ionic liquid. As this mixture was depressurized, the "carbon dioxide returned to its gaseous form, leaving pure solid naphthalene." Ionic liquids and carbon dioxide are not considered perilous because ionic liquids do not evaporate and carbon dioxide is "considered to be an environmentally benign solvent because it is nontoxic and nonflammable and isn't being created in the process; what already exists is simply being used." Scientists Brennecke and Beckman believe this process could be useful for other chemicals. The ten resources listed provide news summaries, background information, and resources related to this recent discovery.

Nannapaneni, Sujani.

1999-01-01

373

Model evaluation experiments in the North Atlantic Basin: simulations in nonlinear terrain-following coordinates  

Microsoft Academic Search

A primitive equation ocean circulation model in nonlinear terrain-following coordinates is applied to a decadal-length simulation of the circulation in the North Atlantic Ocean. In addition to the stretched sigma coordinate, novel features of the model include the utilization of a weakly dissipative, third-order scheme for tracer advection, and a conservative and constancy-preserving time-stepping algorithm. The objectives of the study

Dale B. Haidvogel; Hernan G. Arango; Kate Hedstrom; Aike Beckmann; Paola Malanotte-Rizzoli; Alexander F. Shchepetkin

2000-01-01

374

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

375

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

376

Catalog solvent extraction: anticipate process adjustments  

SciTech Connect

The Modular Caustic-Side Solvent Extraction Unit (MCU) utilizes commercially available centrifugal contactors to facilitate removal of radioactive cesium from highly alkaline salt solutions. During the fabrication of the contactor assembly, demonstrations revealed a higher propensity for foaming than was initially expected. A task team performed a series of single-phase experiments that revealed that the shape of the bottom vanes and the outer diameter of those vanes are key to the successful deployment of commercial contactors in the Caustic-Side Solvent Extraction Process. (authors)

Campbell, S.G.; Brass, E.A.; Brown, S.J.; Geeting, M.W. [Washington Savannah River Company, Savannah River Site, Aiken, SC (United States)

2008-07-01

377

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

378

Copper leaching, solvent extraction, and electrowinning technology  

SciTech Connect

This volume recognizes the growing role of solvent extraction and electrowinning technology in the global copper business. This process is an efficient and cost effective way to extract copper. This proceedings documents the present status of the SX-EW business. It represents a substantial body of historical, scientific, engineering, and commercial information regarding the growth and application of the technology. Sections include: the business and technology of SX-EW, theory and practice of copper leaching, theory and practice of tankhouse operations, and theory and practice of solvent extraction.

Jergensen, G.V. II [ed.

1999-07-01

379

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

380

Weak values and weak coupling maximizing the output of weak measurements  

SciTech Connect

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

Di Lorenzo, Antonio, E-mail: dilorenzo.antonio@gmail.com

2014-06-15

381

Solvent-mediated vibrational energy relaxation from Vaska's complex adducts in binary solvent mixtures.  

PubMed

A vibrational pump-probe and FTIR study was performed on two different adducts of Vaska's complex in two different sets of binary solvent mixtures. The carbonyl vibrational mode in the oxygen adduct exhibits solvatochromic shifts of ~10 cm(-1) in either benzyl alcohol or chloroform relative to benzene-d6, whereas this vibration is nearly unchanged for the iodine adduct for the same three solvents. The width and center frequency of the carbonyl stretch for each adduct are compared to its vibrational lifetime in binary mixtures of benzene-d6 with either benzyl alcohol or chloroform. In neat solvents, the trends in line width, frequency, and vibrational lifetime are consistent for the two adducts, but complex relationships emerge when the trends in each property are compared as a function of mixed solvent composition. ?(CO) is more sensitive to the solvation environment around the trans ligand, whereas the line width and lifetime depend on the environment around the CO group itself. The carbonyl frequency and width vary nonlinearly across the two binary solvent series, indicating preferential solvation. In contrast, the vibrational lifetime changes linearly with solvent composition and is correlated with the mole fraction of chloroform but anticorrelated with the mole fraction of benzyl alcohol. The results are explained by differences in the densities of solvent modes that affect intermolecular relaxation of the carbonyl mode. PMID:23531048

Jones, Brynna H; Huber, Christopher J; Massari, Aaron M

2013-07-25

382

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

383

Overdamping by weakly coupled environments  

NASA Astrophysics Data System (ADS)

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

Esposito, Massimiliano; Haake, Fritz

2005-12-01

384

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-U(2)Cl(2)(bdc)(3)(DMF)(4) (1) and M-U(2)Cl(2)(bdc)(3)(DMF)(4) (2) 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, U(2)(bdc)(4)(DMF)(4) (3). 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 U(6)O(4)(OH)(4)(H(2)O)(6)(bdc)(6)·10DMF solid (containing a hexanuclear sub-unit) is observed for temperature 110-120 °C and the H(2)O/U molar ratio in the range of 2-10. At higher temperature (140-150 °C), a distinct phase appeared, U(2)O(2)(bdc)(2)(DMF) (4), 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 UO(2). PMID:25428593

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

2015-02-14

385

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

2010-09-23

386

Functional weakness and sensory disturbance  

PubMed Central

In the diagnosis of functional weakness and sensory disturbance, positive physical signs are as important as absence of signs of disease. Motor signs, particularly Hoover's sign, are more reliable than sensory signs, but none should be used in isolation and must be interpreted in the overall context of the presentation. It should be borne in mind that a patient may have both a functional and an organic disorder. PMID:12185152

Stone, J; Zeman, A; Sharpe, M

2002-01-01

387

Selective Synthesis of Ruthenium(II) Metalla[2]Catenane via Solvent and Guest-Dependent Self-Assembly.  

PubMed

The coordination-driven self-assembly of an anthracene-functionalized ditopic pyridyl donor and a tetracene-based dinuclear Ru(II) acceptor resulted in an interlocked metalla[2]catenane, [M2L2]2, in methanol and a corresponding monorectangle, [M2L2], in nitromethane. Subsequently, guest template, solvent, and concentration effects allowed the self-assembly to be reversibly fine-tuned among monorectangle and catenane structures. PMID:25822323

Lee, HyeWoo; Elumalai, Palani; Singh, Nem; Kim, Hyunuk; Lee, Sang Uck; Chi, Ki-Whan

2015-04-15

388

Preparation and characterization of CdSe nanoparticles in the presence of Triocytlphosphine as solvent and capping agent  

Microsoft Academic Search

Triocytlphosphine (TOP)-capped CdSe nanoparticles (NPs) have been successfully prepared by the one-pot solution growth method at 240 °C under argon atmosphere. In particular, The TOP used in this process as the single coordinating solvent is favorable for probing capping mechanism of CdSe NPs surface. The growth process and characterization of CdSe NPs were determined by photoluminescence (PL) spectroscopy, X-ray diffraction (XRD),

Shutang Chen; Xiaoling Zhang; Yanbing Zhao; Jilin Yan; Weihong Tan

2009-01-01

389

Cosmology with Weak Lensing Surveys  

E-print Network

Weak gravitational lensing surveys measure the distortion of the image of distant sources due to the deflections of light rays by the fluctuations of the gravitational potential along the line of sight. Since they probe the non-linear matter power spectrum itself at medium redshift such surveys are complimentary to both galaxy surveys (which follow stellar light) and cosmic microwave background observations (which probe the linear regime at high redshift). Ongoing CMB experiments such as WMAP and the future Planck satellite mission will measure the standard cosmological parameters with unprecedented accuracy. The focus of attention will then shift to understanding the nature of dark matter and vacuum energy: several recent studies suggest that lensing is the best method for constraining the dark energy equation of state. During the next 5 year period ongoing and future weak lensing surveys such as the Joint Dark Energy Mission (JDEM, e.g. SNAP) or the Large-aperture Synoptic Survey Telescope (LSST) will play a major role in advancing our understanding of the universe in this direction. In this review article we describe various aspects of weak lensing surveys and how they can help us in understanding our universe.

Dipak Munshi; Patrick Valageas

2005-09-27

390

Are subduction zones inherently weak?  

NASA Astrophysics Data System (ADS)

An outstanding question in geodynamics is how weak are plate boundaries when compared to their interiors? Particularly, how weak are subduction zone interfaces? Because subduction is believed to be the major driver of plate tectonics, this question is of fundamental importance for geodynamics. Several lines of evidence suggest that subduction zones are weak and that the unique availability of water on Earth plays a key role. We have evaluated the strength of subduction zone interfaces using two approaches: i) an empirical relationship between shear stress at the interface and subduction velocity, deduced from laboratory experiments of subduction; and ii) a parametric study of natural subduction zones that provides new insights on subduction zone interface strength. Our results suggest that subduction is only mechanically feasible when shear stresses along the plate interface are relatively low (< 33 MPa). To account for this global requirement, we propose that there is a feedback mechanism between subduction velocity, water release rate from the subducting plate and serpentinization and weakening of the forearc mantle that may explain how relatively low shear stresses are maintained at subduction interfaces globally.

Duarte, Joao; Schellart, Wouter; Cruden, Alexander; Gutscher, Marc-André

2014-05-01

391

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

392

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

393

Analysis of creams. II. Quantitative determination of drugs in creams by titration in non-aqueous solvents.  

PubMed

The possibilities for the determination of active components in creams by acid-base titrations in non-aqueous solvents were investigated. Interference by cream-base components with the titration of weak organic bases and their halides with perchloric acid in acetic acid, and with the titration of weak acids with tetrabutylammonium hydroxide in N,N-dimethylformamide were studied. It appeared to be possible to determine alkaloid halides, salicylic acid, hexachlorophene and methyl salicylate without previous clean-up of the cream samples. PMID:6280125

Van de Vaart, F J; Hulshoff, A; Indemans, A W

1982-02-19

394

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

395

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

396

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...

397

Reaction paths in donor solvent coal liquefaction  

Microsoft Academic Search

The classic studies of Sol Weller and his collaborators1,2 provided the working model for most American investigations of donor solvent coal liquefaction. The investigations, particularly at what is now the Pittsburgh Energy Research Centre of ERDA, at what is now Conoco Coal Development Company, at Pittsburg and Midway Coal Company and at the University of Utah, added notably to Weller's

Arthur M. Squires

1978-01-01

398

Mixed Solvent Reactive Recrystallization of Sodium Carbonate  

Microsoft Academic Search

Investigation of the reactive recrystallization of trona (sodium sesquicarbonate) and sodium bicarbonate to sodium carbonate (soda) in a mixed solvent led to the design of several alternative, less energy consumptive, economically very attractive process routes for the production of soda from all principal sodium carbonate sources. The kinetics of the recrystallization as well as of the superimposed chemical reaction, the

R. S. Gaertner

2005-01-01

399

Modeling Organic Solvents Permeation Through Protective Gloves  

Microsoft Academic Search

Several researchers have studied the diffusion of organic solvents through chemical protective gloves and have estimated the diffusion coefficients by using various models. In this study, permeation experiments of benzene, toluene, and styrene through nitrile and Neoprene gloves were conducted using the ASTM F-739 standard test method. The diffusion coefficients were estimated using several models from the literature. Using a

Keh-Ping Chao; Ven-Shing Wang; Pak-Hing Lee

2004-01-01

400

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...

401

A Solvent Extraction Process for Tar Sand  

Microsoft Academic Search

A process has been investigated for solvent extraction of bitumen from Sunnyside, Utah, tar sands. The Sunnyside deposit, in east central Utah, has 1 to 2 billion barrels of geological reserves with a richness of 6 to 10 wtX bitumen. In this process, the ore is crushed and the bitumen is dissolved from the mineral in mix tanks. The bitumen

R. J. Graham; J. J. Helstrom; R. L. Mehlberg

1987-01-01

402

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...

403

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...

404

Industrial solvents step up to the mound  

SciTech Connect

In the field of industrial solvents, 1,1,1-trichloroethane is known for its ability to cover the bases. Versatile, the organic chemical is widely used for a variety of applications, from vapor degreasing to cold cleaning. But its number is about to be retired. Under a timetable established by the Montreal Protocol, production of this ozone-depleting compound is scheduled to be phased out by the end of the year. As the deadline approaches, the impact of the inevitable exit of 1,1,1 from the marketplace is being cushioned by three developments: the gradual shutdown of some capacity, exemptions for the continued production of 1,1,1 for certain applications, and the rapid development of alternative solvents. So far, industry observers agree, none of the alternative solvents quite match the performance of 1,1,1. Certainly there is some interest in finding a one-for-one replacement for 1,1,1, but it is not the top priority for companies currently pursuing the development of alternative solvents. Instead, they are focused on creating families of environmentally safe products that closely match the performance of 1,1,1 in specific applications. The paper discusses this technology.

Hairston, D.

1995-06-01

405

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

406

RECUPERAÇÃO DE BIOPOLÍMERO BACTERIANO POR SOLVENTES  

Microsoft Academic Search

This research has as purpose checking the solvents influence in the income and the productivity in the recovery of the cellulose produced by the Acetobacter xilynum (ATCC 23769). The fermentation process happened in the static cultivation, having as culture medium ripe coconut water (200ml). It was made an experimental following line of 2 4 , with different salts solutions as

Denise Milleo Almeida; Gilvan Wosiacki; Guataçara dos Santos Junior

2008-01-01

407

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

408

Structure and Solvent Properties of Microemulsions  

ERIC Educational Resources Information Center

A microscale laboratory experiment to investigate the formation and utility of microemulsions is described. Microemulsions are technologically important fluids that can reduce the use of toxic organic solvents. In the experiment, students prepare a microemulsion and compare the solubility of sudan III dye in the microemulsion and in dodecane. They…

Katz, Civia A.; Calzola, Zachary J.; Mbindyo, Jeremiah K. N.

2008-01-01

409

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

410

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

411

Maintenance Tendency in Coordinated Rhythmic  

E-print Network

. Rosenblumt and M. T. Turveyt Evidence from the oscillatory behavior of fish fins and the crayfish swimmeret coordination: two rhythmic units oscillating at a single, common period and at a bounded phase relation

412

ICCT Clearinghouse Transportation Coordination Primer  

E-print Network

gained expertise that will help the process run smoother while maintaining its integrity. Fourth Edition....................................................................................................................10 National and State Recognition of ICCT Coordination Primer Process .......................................................................................................................26 Downstate Federal Funding Chart

Illinois at Chicago, University of

413

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

414

47 CFR 80.513 - Frequency coordination.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false Frequency coordination. 80.513 Section 80...Marine Utility Stations § 80.513 Frequency coordination. (a) Except as...located in an area having a recognized frequency coordinating committee must be...

2010-10-01

415

47 CFR 80.513 - Frequency coordination.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 2011-10-01 false Frequency coordination. 80.513 Section 80...Marine Utility Stations § 80.513 Frequency coordination. (a) Except as...located in an area having a recognized frequency coordinating committee must be...

2011-10-01

416

33 CFR 166.103 - Geographic coordinates.  

Code of Federal Regulations, 2010 CFR

...FAIRWAYS General § 166.103 Geographic coordinates. Geographic coordinates expressed in terms of latitude or longitude, or both, are not intended...1983 (NAD 83), unless such geographic coordinates are expressly...

2010-07-01

417

33 CFR 165.8 - Geographic coordinates.  

Code of Federal Regulations, 2010 CFR

...AREAS General § 165.8 Geographic coordinates. Geographic coordinates expressed in terms of latitude or longitude, or both, are not intended...1983 (NAD 83), unless such geographic coordinates are expressly...

2010-07-01

418

33 CFR 166.103 - Geographic coordinates.  

Code of Federal Regulations, 2011 CFR

...FAIRWAYS General § 166.103 Geographic coordinates. Geographic coordinates expressed in terms of latitude or longitude, or both, are not intended...1983 (NAD 83), unless such geographic coordinates are expressly...

2011-07-01

419

33 CFR 165.8 - Geographic coordinates.  

Code of Federal Regulations, 2011 CFR

...AREAS General § 165.8 Geographic coordinates. Geographic coordinates expressed in terms of latitude or longitude, or both, are not intended...1983 (NAD 83), unless such geographic coordinates are expressly...

2011-07-01

420

47 CFR 80.513 - Frequency coordination.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Frequency coordination. 80.513 Section 80...Marine Utility Stations § 80.513 Frequency coordination. (a) Except as...located in an area having a recognized frequency coordinating committee must be...

2013-10-01

421

47 CFR 80.513 - Frequency coordination.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 2012-10-01 false Frequency coordination. 80.513 Section 80...Marine Utility Stations § 80.513 Frequency coordination. (a) Except as...located in an area having a recognized frequency coordinating committee must be...

2012-10-01

422

Polyporous metal-coordination frameworks.  

PubMed

Starting from a chiral building block--?-cyclodextrin--and rubidium salts, the crystallization of a complex of chiral helices, which constitute a "green" porous coordination polymer, has been realized. Cyclodextrin molecules coordinated by rubidium ions form porous, infinitely long left-handed helical channels, interdigitated with each other. A theoretical examination of the potential of this new material to act as a medium for chiral separation is presented. PMID:22375911

Gassensmith, Jeremiah J; Smaldone, Ronald A; Forgan, Ross S; Wilmer, Christopher E; Cordes, David B; Botros, Youssry Y; Slawin, Alexandra M Z; Snurr, Randall Q; Stoddart, J Fraser

2012-03-16

423

Definition and determination of the triplet-triplet energy transfer reaction coordinate  

SciTech Connect

A definition of the triplet-triplet energy transfer reaction coordinate within the very weak electronic coupling limit is proposed, and a novel theoretical formalism is developed for its quantitative determination in terms of internal coordinates The present formalism permits (i) the separation of donor and acceptor contributions to the reaction coordinate, (ii) the identification of the intrinsic role of donor and acceptor in the triplet energy transfer process, and (iii) the quantification of the effect of every internal coordinate on the transfer process. This formalism is general and can be applied to classical as well as to nonvertical triplet energy transfer processes. The utility of the novel formalism is demonstrated here by its application to the paradigm of nonvertical triplet-triplet energy transfer involving cis-stilbene as acceptor molecule. In this way the effect of each internal molecular coordinate in promoting the transfer rate, from triplet donors in the low and high-energy limit, could be analyzed in detail.

Zapata, Felipe; Marazzi, Marco; Castaño, Obis; Frutos, Luis Manuel, E-mail: luisma.frutos@uah.es [Departamento de Química Física, Universidad de Alcalá, 28871 Alcalá de Henares, Madrid (Spain); Acuña, A. Ulises [Instituto de Química Física “Rocasolano”, C.S.I.C., Serrano 119, 28006 Madrid (Spain)] [Instituto de Química Física “Rocasolano”, C.S.I.C., Serrano 119, 28006 Madrid (Spain)

2014-01-21

424

Safety in the Chemical Laboratory: Cyclohexane as a Cryoscopic Solvent.  

ERIC Educational Resources Information Center

Suggests that cyclohexane be used as a solvent in experiments usually using benzene, which has been placed on the list of chemicals that are confirmed carcinogens. Reasons for selection of cyclohexane and experimental procedures using this solvent are described. (CS)

Steffel, Margaret J.

1981-01-01

425

Structure and Dynamics of Conjugated Polymers in Liquid Crystalline Solvents  

NASA Astrophysics Data System (ADS)

A combination of single-molecule spectroscopy and analysis with simulations is used to provide detailed information about the structural and dynamic properties of a fluorescent polymer MEH-PPV (poly[2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylenevinylene]) immersed in a nematic and smectic solvent. In nematic solvents, single-polymer molecules are oriented strongly along the solvent director, much more so than the solvent molecules, confirming Onsager's old prediction. The diffusion anisotropy parallel and perpendicular to the solvent director, however, is less than two, which is similar to that of a spherical colloid in a nematic solvent. In smectic solvents, there is a second orientation of the dissolved polymer perpendicular to the solvent director, which we hypothesize is caused by the polymer occupying the interlayer volume. The research discussed here emphasizes the importance of organization in complex fluids and suggests that the interplay of order on different length scales could be exploited to fabricate novel nanostructured materials.

Barbara, P. F.; Chang, W.-S.; Link, S.; Scholes, G. D.; Yethiraj, Arun

2007-05-01

426

Solvent Selection Use dry ice/isopropanol for cooling baths  

E-print Network

for single- solvent systems, azeotropes, and solvent mixtures with >10°C difference in boiling point. Use, or for high-boiling liquids simply use air. Use Dry Column Vacuum Chromatography to purify large samples

Chan, Hue Sun

427

The Ideal Solvent for Paper Chromatography of Food Dyes.  

ERIC Educational Resources Information Center

Uses paper chromatography with food dyes to provide a simple and inexpensive basis for teaching chromatography. Provides experimental methodology and tabled results. Includes a solvent system comparison (Rf) for seven dyes and twenty-two solvents. (MVL)

Markow, Peter G.

1988-01-01

428

EXTRACTION OF CHEMICAL POLLUTANTS FROM INDUSTRIAL WASTEWATERS WITH VOLATILE SOLVENTS  

EPA Science Inventory

Solvent extraction with volatile solvents was studied as a method for treating wastewaters from petroleum refineries and petrochemical plants. Extraction is most attractive when the loading of organics is high, when substances are present which pose difficulties for biological ox...

429

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...

430

Organic Solvent Tropical Report [SEC 1 and 2  

SciTech Connect

This report provides the basis for closing the organic solvent safety issue. Sufficient information is presented to conclude that risk posed by an unmitigated organic solvent fire is within risk evaluation guidelines.

COWLEY, W.L.

2000-06-21

431

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

432

TRIFORCE: Tessellated Semianalytical Solvent Exposed Surface Areas and Derivatives.  

PubMed

We present a new approach to the calculation of solvent-accessible surface areas of molecules with potential application to surface area based methods for determination of solvation free energies. As in traditional analytical and statistical approaches, this new algorithm, called TRIFORCE, reports both component areas and derivatives as a function of the atomic coordinates and radii. Unique to TRIFORCE are the rapid and scalable approaches for the determination of sphere intersection points and numerical estimation of the surface areas, derivatives, and other properties that can be associated with the surface area facets. The algorithm performs a special tessellation and semianalytical integration that uses a precomputed look-up table. This provides a simple way to balance numerical accuracy and memory usage. TRIFORCE calculates derivatives in the same manner, enabling application in force-dependent activities such as molecular geometry minimization. TRIFORCE is available free of charge for academic purposes as both a C++ library, which can be directly interfaced to existing molecular simulation packages, and a web-accessible application. PMID:25221446

Drechsel, Nils J D; Fennell, Christopher J; Dill, Ken A; Villà-Freixa, Jordi

2014-09-01

433

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

434

Weak quasielastic production of hyperons  

SciTech Connect

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

Singh, S. K. [Departamento de Fisica Teorica and IFIC, Centro Mixto Universidad de Valencia CSIC, Institutos de Investigacion de Paterna, Aptdo. 22085, 46071 Valencia (Spain); Department of Physics, Aligarh Muslim University, Aligarh- 202002 (India); Vacas, M. J. Vicente [Departamento de Fisica Teorica and IFIC, Centro Mixto Universidad de Valencia CSIC, Institutos de Investigacion de Paterna, Aptdo. 22085, 46071 Valencia (Spain)

2006-09-01

435

Weak $?$ production off the nucleon  

E-print Network

The weak $\\eta$-meson production off the nucleon induced by (anti)neutrinos is studied at low and intermediate energies, the range of interest for several ongoing and future neutrino experiments. We consider Born diagrams and the excitation of $N^\\ast (1535)S_{11}$ and $N^\\ast(1650)S_{11}$ resonances. The vector part of the N-$S_{11}$ transition form factors has been obtained from the MAID helicity amplitudes while the poorly known axial part is constrained with the help of the partial conservation of the axial current (PCAC) and assuming the pion-pole dominance of the pseudoscalar form factor.

M. Rafi Alam; L. Alvarez-Ruso; M. Sajjad Athar; M. J. Vicente Vacas

2013-03-24

436

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

437

Weak gravitational lensing with SKA  

E-print Network

I shall outline the basic principles and some observational aspects of weak gravitational lensing, and discuss several applications of this powerful tool in observational cosmology. It will be explained why the applications have been restricted to optical observations up to now, and why SKA is going to change this. I conclude with a few general remarks on a comparison between SKA and the NGST, both being facilities which will provide a tremendous step forward in radio and near-IR astronomy, respectively, into completely unknown territory.

Peter Schneider

1999-07-12

438

Revised Coordinates for Apollo Hardware  

NASA Astrophysics Data System (ADS)

The Narrow Angle Camera (NAC) on the Lunar Reconnaissance Orbiter provides direct imaging, at pixel scales of 0.5 to 1.0 meter, of anthropogenic equipment left on the Moon. We identified the descent stages of the lunar modules, central stations of the Apollo Lunar Surface Experiments Package, Laser Ranging Retroreflectors (LRRRs), and Lunar Roving Vehicles in each NAC image of the Apollo landing sites. The pixel coordinates of those objects were then converted to latitude and longitude coordinates using SPICE routines in the U.S. Geological Survey Integrated System for Imagers and Spectrometers. For images that contained an LRRR, pointing information was updated to match the well known LRRR coordinates. Final coordinates for each object are reported as averages from multiple images. NAC observations allow refinement of the locations of these objects and result in a more accurate geodetic referencing at these historic sites. Additionally, the anthropogenic coordinate analysis enables realistic error estimates for NAC derived coordinates for features anywhere on the Moon.

Wagner, R. V.; Speyerer, E. J.; Burns, K. N.; Danton, J.; Robinson, M. S.

2012-08-01

439

Temporal coordination between performing musicians.  

PubMed

Many common behaviours require people to coordinate the timing of their actions with the timing of others' actions. We examined whether representations of musicians' actions are activated in coperformers with whom they must coordinate their actions in time and whether coperformers simulate each other's actions using their own motor systems during temporal coordination. Pianists performed right-hand melodies along with simple or complex left-hand accompaniments produced by themselves or by another pianist. Individual performers' preferred performance rates were measured in solo performance of the right-hand melody. The complexity of the left-hand accompaniment influenced the temporal grouping structure of the right-hand melody in the same way when it was performed by the self or by the duet partner, providing some support for the action corepresentation hypothesis. In contrast, accompaniment complexity had little influence on temporal coordination measures (asynchronies and cross-correlations between parts). Temporal coordination measures were influenced by a priori similarities between partners' preferred rates; partners who had similar preferred rates in solo performance were better synchronized and showed mutual adaptation to each other's timing during duet performances. These findings extend previous findings of action corepresentation and action simulation to a task that requires precise temporal coordination of independent yet simultaneous actions. PMID:21929475

Loehr, Janeen D; Palmer, Caroline

2011-11-01

440

7 CFR 51.894 - Weak.  

Code of Federal Regulations, 2012 CFR

...VEGETABLES AND OTHER PRODUCTS 1,2 (INSPECTION, CERTIFICATION, AND STANDARDS) United States Standards for Grades of Table Grapes (European or Vinifera Type) 1 Definitions § 51.894 Weak. Weak means that individual berries are somewhat...

2012-01-01

441

Solvent effects on photophysical parameters for coumarin laser dyes  

NASA Astrophysics Data System (ADS)

The red shifts of absorption and emission bands of coumarin laser dyes were studied as a function of solvent polarity and hydrogen bonding. Spectra were correlated with solvent parameters, pi and alpha, and those solvents resulting in the largest Stokes shifts of dye emission were identified. Solvent effects on emission yield and lifetime revealed a major non-radiative decay path for dyes in which the 7 amine function is free to adopt a non-planar conformation.

Jones, G., II; Jackson, W. R.; Kanoktanaporn, S.; Halpern, A. M.

1980-01-01

442

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

443

Iridium-catalyzed asymmetric hydrogenation yielding chiral diarylmethines with weakly coordinating or noncoordinating substituents.  

PubMed

Diarylmethine-containing stereocenters are present in pharmaceuticals and natural products, making the synthetic methods that form these chiral centers are important in industry. We have applied iridium complexes with novel N,P-chelating ligands to the asymmetric hydrogenation of trisubstituted olefins, forming diarylmethine chiral centers in high conversions and excellent enantioselectivities (up to 99% ee) for a broad range of substrates. Our results support the hypothesis that steric hindrance in one specific area of the catalyst is playing a key role in stereoselection, as the hydrogenation of substrates differing little at the prochiral carbon occurred with high enantioselectivity. As a result, excellent stereodiscrimination was obtained even when the prochiral carbon bore, for example, phenyl and p-tolyl groups. PMID:19552449

Tolstoy, Päivi; Engman, Mattias; Paptchikhine, Alexander; Bergquist, Jonas; Church, Tamara L; Leung, Abby W-M; Andersson, Pher G

2009-07-01

444

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

445

Comparing the energetic and dynamic contributions of solvent to very low barrier isomerization using dynamic steady-state vibrational spectroscopy.  

PubMed

We report the solvent-dependent dynamics of carbonyl site exchange for Fe(CO)3(?(4)-norbornadiene) (FeNBD) in a series of linear and nonlinear alkanes. The barrier to exchange is very low (?1.5 kcal/mol), and the resulting carbonyl dynamics are rapid enough to lead to a change in the vibrational spectra, which we use to extract the ultrafast rates of exchange from linear Raman spectra of FeNBD. The dynamics of the carbonyl exchange has a weak dependence upon the solvent, and we analyze this dependence in terms of energetic (reaction field) and dynamic (Kramers theory) models of solvent effects. We find that both models can reproduce the observed solvent dependence but that the dynamic model provides a more physically satisfying picture for the solvent effects than does the energetic model. Finally, we find that cyclohexane is more strongly coupled to the dynamics of FeNBD than are the noncyclic alkanes. PMID:25811244

Giordano, Andrea N; Lear, Benjamin J

2015-04-16

446

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

447

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

448

A Novel Azeotropic Mixture for Solvent Extraction of Edible Oils  

Microsoft Academic Search

Hexane, the common solvent for extraction of edible oils from seeds is no more considered safe due to the presence of solvent in oil and also solvent vapour, a hazardous air pollutant. We have carried out the experiments with bahera (Terminalia bellerica Roxb) and flax seed (Linum usitatissimum ) oil as these oils are highly used in food for their

D. Bera; D. Lahiri; Antonella De Leonardis; K. B. De; A. Nag

449

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

450

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...

451

Catalytic coal liquefaction with treated solvent and SRC recycle  

DOEpatents

A process is described 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. 2 figs.

Garg, D.; Givens, E.N.; Schweighardt, F.K.

1986-12-09

452

DEACIDIFICATION OF DAGANG SECOND LUBRICATING OIL DISTILLATE BY COMBINED SOLVENT  

Microsoft Academic Search

A combined solvent was used for getting rid of the acid components of lubricating oil distillates. Data indicate that this solvent can remove most of the acid matters. The deacidified oil has better light stability than hydrodeacidified oils. This solvent can be reused and recovered. The reaction conditions are easy to be fulfilled. This deacidification method is an effective technology

Yanzhen Wang; Kai Wang; Hongxia Guan; Gang Li

2001-01-01

453

Field demonstration for PD680 solvent replacement. interim report  

Microsoft Academic Search

As part of the second phase in development of environmentally compliant solvent alternatives to P-D-680, field demonstrations were initiated at Ft. Lewis WA, Ft. Hood TX, and Kelly Air Force Base. The main objectives of this demonstration were to validate performance of candidate solvents with existing military equipment and to determine the environmental applicability for these candidate solvents. Four (4)

I. S. Rhee; C. Velez

1996-01-01

454

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

2015-02-18

455

Covariance of Weak Lensing Observables  

E-print Network

Analytical expressions for covariances of weak lensing statistics related to the aperture mass $\\Map$ are derived for realistic survey geometries such as SNAP for a range of smoothing angles and redshift bins. We incorporate the contributions to the noise due to the intrinsic ellipticity distribution and the effects of finite size of the catalogue. Extending previous results to the most general case where the overlap of source populations is included in a complete analysis of error estimates, we study how various angular scales in various redshifts are correlated and how the estimation scatter changes with survey parameters. Dependence on cosmological parameters and source redshift distributions are studied in detail. Numerical simulations are used to test the validity of various ingredients to our calculations. Correlation coefficients are defined in a way that makes them practically independent of cosmology. They can provide important tools to cross-correlate one or more different surveys, as well as various redshift bins within the same survey or various angular scales from same or different surveys. Dependence of these coefficients on various models of underlying mass correlation hierarchy is also studied. Generalisations of these coefficients at the level of three-point statistics have the potential to probe the complete shape dependence of the underlying bi-spectrum of the matter distribution. A complete error analysis incorporating all sources of errors suggest encouraging results for studies using future space based weak lensing surveys such as SNAP.

Dipak Munshi; Patrick Valageas

2004-09-20

456

Quantum Weak Measurements and Cosmology  

NASA Astrophysics Data System (ADS)

The indeterminism of quantum mechanics generally permits the independent specification of both an initial and a final condition on the state. Quantum pre- and post-selection of states opens up a new, experimentally testable, sector of quantum mechanics, when combined with statistical averages of identical weak measurements. In this paper I apply the theory of weak quantum measurements combined with pre- and post-selection to cosmology. Here, pre-selection means specifying the wave function of the universe or, in a popular semi-classical approximation, the initial quantum state of a subset of quantum fields propagating in a classical background spacetime. The novel feature is post-selection: the additional specification of a condition on the quantum state in the far future. I discuss "natural" final conditions, and show how they may lead to potentially large and observable effects at the present cosmological epoch. I also discuss how pre- and post-selected quantum fields couple to gravity via the DeWitt-Schwinger effective action prescription, in contrast to the expectation value of the stress-energy-momentum tensor, resolving a vigorous debate from the 1970s. The paper thus provides a framework for computing large-scale cosmological effects arising from this new sector of quantum mechanics. A simple experimental test is proposed. [Editors note: for a video of the talk given by Prof. Davies at the Aharonov-80 conference in 2012 at Chapman University, see http://quantum.chapman.edu/talk-13.

Davies, P. C. W.

457

Intermittency in Weak Magnetohydrodynamic Turbulence  

E-print Network

Intermittency is investigated using decaying direct numerical simulations of incompressible weak magnetohydrodynamic turbulence with a strong uniform magnetic field ${\\bf b_0}$ and zero cross-helicity. At leading order, this regime is achieved via three-wave resonant interactions with the scattering of two of these waves on the third/slow mode for which $k_{\\parallel} = 0$. When the interactions with the slow mode are artificially reduced the system exhibits an energy spectrum with $k_{\\perp}^{-3/2}$, whereas the expected exact solution with $k_{\\perp}^{-2}$ is recovered with the full nonlinear system. In the latter case, strong intermittency is found when the vector separation of structure functions is taken transverse to ${\\bf b_0}$ - at odds with classical weak turbulence where self-similarity is expected. This surprising result, which is being reported here for the first time, may be explained by the influence of slow modes whose regime belongs to strong turbulence. We derive a new log--Poisson law, $\\zeta_p = p/8 +1 -(1/4)^{p/2}$, which fits perfectly the data and highlights the dominant role of current sheets.

Romain Meyrand; Khurom H. Kiyani; Sebastien Galtier

2014-09-07

458

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

459

Effect of metal coordination on photocurrent response properties of a tetrathiafulvalene organogel film.  

PubMed

Organic low molecular weight gelators with a tetrathiafulvalene (TTF) unit have received considerable attention because the formed gels usually exhibit redox active response and conducting or semiconducting properties. However, to our knowledge, metal coordination systems have not been reported for TTF-derived gels up to date. We have designed and synthesized a series of TTF derivatives with a diamide-diamino moiety that can coordinate to specific metal ions with square coordination geometry. Gelation properties and morphologies of the films prepared by the gelators in different hydrophobic solvents are characterized. The TTF derivative with a dodecyl group shows effective gelation properties, and electrodes with the organogel films are prepared. The effect of the Ni(II) and Cu(II) coordination on the photocurrent response property of the electrodes is examined. The metal square coordination significantly increases the photocurrent response. This gel system is the first metal coordination related TTF-gel-based photoelectric material. The mechanism of the metal coordination-improved photocurrent response property is discussed based on the crystal structural analysis and theoretical calculations. PMID:24646411

Ji, Shu-Fang; Sun, Yong-Gang; Huo, Peng; Shen, Wei-Chun; Huang, Yu-De; Zhu, Qin-Yu; Dai, Jie

2014-04-01

460

Weak D in the Tunisian population  

PubMed Central

Background More than 90 weak D types have been discovered to date. As there are no published data on the frequencies of weak D types in the Tunisian population, the aim of this study was to determine the composition of weak D alleles in our population. Material and methods Blood samples from 1777 D+ and 223 D? blood donors were tested for markers 809G, 1154C, 8G, 602G, 667G, 446A, and 885T relative to translation start codon by polymerase chain reaction with sequence-specific primers to estimate the frequencies of weak D type 1, weak D type 2, weak D type 3, weak D type 4, weak D type 5 and weak D type 11 in our population. Twenty-three samples with positive reactions were re-evaluated by DNA sequencing of RHD exons 1–10 and adjacent intronic sequences. Results Among the D+ donor cohort, weak D type 4 was the most prevalent allele (n=33, 1.2%) followed by weak D type 2 (n=6, 0.17%), weak D type 1 (n=4, 0.11%), and weak D type 5 (n=1, 0.28%) and weak D type 11 (n=1, 0.28%). RHD sequencing identified a weak D type 4.0 allele in all 19 samples tested. Among the D? pool, comprising 223 samples, we detected one sample with weak D type 4.0 associated with a C+c+E?e+ phenotype which had been missed by routine serological methods. Discussion Weak D type 4.0 appears to be the most prevalent weak D in our population. However, all samples must be sequenced in order to determine the exact subtype of weak D type 4, since weak D type 4.2 has considerable clinical importance, being associated with anti-D alloimmunisation. One case of weak D type 4 associated with dCe in trans had been missed by serology, so quality control of serological tests should be developed in our country. PMID:25369614

Ouchari, Mouna; Romdhane, Houda; Chakroun, Taher; Abdelkefi, Saida; Houissa, Batoul; Hmida, Slama; Yacoub, Saloua Jemni

2015-01-01

461

Local shear instabilities in weakly ionized, weakly magnetized disks  

NASA Technical Reports Server (NTRS)

We extend the analysis of axisymmetric magnetic shear instabilities from ideal magnetohydrodynamic (MHD) flows to weakly ionized plasmas with coupling between ions and neutrals caused by collisions, ionization, and recombination. As part of the analysis, we derive the single-fluid MHD dispersion relation without invoking the Boussinesq approximation. This work expands the range of applications of these instabilities from fully ionized accretion disks to molecular disks in galaxies and, with somewhat more uncertainty, to protostellar disks. Instability generally requires the angular velocity to decrease outward, the magnetic field strengths to be subthermal, and the ions and neutrals to be sufficiently well coupled. If ionization and recombination processes can be neglected on an orbital timescale, adequate coupling is achieved when the collision frequency of a given neutral with the ions exceeds the local epicyclic freqency. When ionization equilibrium is maintained on an orbital timescale, a new feature is present in the disk dynamics: in contrast to a single-fluid system, subthermal azimuthal fields can affect the axisymmetric stability of weakly ionized two-fluid systems. We discuss the underlying causes for this behavior. Azimuthal fields tend to be stabilizing under these circumstances, and good coupling between the neutrals and ions requires the collision frequency to exceed the epicyclic frequency by a potentially large secant factor related to the magnetic field geometry. When the instability is present, subthermal azimuthal fields may also reduce the growth rate unless the collision frequency is high, but this is important only if the field strengths are very subthermal and/or the azimuthal field is the dominant field component. We briefly discuss our results in the context of the Galactic center circumnuclear disk, and suggest that the shear instability might be present there, and be responsible for the observed turbulent motions.

Blaes, Omer M.; Balbus, Steven A.

1994-01-01

462

Measuring solvent barrier properties of paper  

NASA Astrophysics Data System (ADS)

New methods for measuring barrier properties against solvents, acids and bases on dispersion coated paper were developed and investigated. Usability, reliability and repeatability were compared both between the new methods and with the standardized method for measuring barrier properties against water vapor. Barrier properties could be measured with all methods and the results obtained by the different methods were in correlation with each other. A qualitative method based on a trace color provided an indicative result, whereas further developed methods also took into account the durability. The effective barrier lifetime could be measured by measuring the conductivity through the substrate as a function of time, or by utilizing a glass prism where the change in refractive index caused by penetrated liquid was monitored, also as a function of time. Barrier properties against water and humidity were also measured and were found not to be predictors for barrier properties against either solvents, or acids or bases, which supports the need to develop new methods.

Bollström, Roger; Saarinen, Jarkko J.; Räty, Jukka; Toivakka, Martti

2012-01-01

463

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

464

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

465

Structuring of polymer solutions upon solvent evaporation  

NASA Astrophysics Data System (ADS)

The morphology of solution-cast, phase-separated polymers becomes finer with increasing solvent evaporation rate. We address this observation theoretically for a model polymer where demixing is induced by steady solvent evaporation. In contrast to what is the case for a classical, thermal quench involving immiscible blends, the spinodal instability initially develops slowly and the associated length scale is not time invariant but decreases with time as t-1 /2. After a time lag, phase separation accelerates. Time lag and characteristic length exhibit power-law behavior as a function of the evaporation rate with exponents of -2 /3 and -1 /6 . Interestingly, at later stages the spinodal structure disappears completely while a second length scale develops. The associated structure coarsens but does not follow the usual Lifshitz-Slyozov-Wagner kinetics.

Schaefer, C.; van der Schoot, P.; Michels, J. J.

2015-02-01

466

Solvent properties of liquid and supercritical hydrofluorocarbons  

SciTech Connect

The dipolarity/polarizability parameter {pi}{sup *}, introduced by Kamlet and Taft, was measured for difluoromethane (HFC 32) and pentafluoroethane (HFC 125) and compared with those previously reported for 1,1,1,2-tetrafluoroethane (HFC 134a). This was carried out as a function of temperature and pressure, to cover the liquid and supercritical states over the range 30--130 C and 40--300 bar. The change in dipolarity/polarizability with the reduced density is explained in terms of local density augmentation and a van der Waals model is used to predict the changes in solvent properties. The mean sphere approximation (MSA) model was applied to the data and found to produce an excellent fit for all of the solvents in both the liquid and supercritical states.

Abbott, A.P.; Eardley, C.A. [Leicester Univ. (United Kingdom). Chemistry Dept.] [Leicester Univ. (United Kingdom). Chemistry Dept.

1999-04-01

467

Solvent Extract, Plant Extraction Correspondence to Author:  

E-print Network

ABSTRACT: Cyamopsis tetragonoloba L. is belongs to the family Fabaceae. It is used as herbal and as vegetable from ancient times. It is abundant in tropical region of Africa and Asia. Preliminary phytochemicals investigations have been carried out on the seed extract using n-Hexane, Ethyl Acetate, Acetone, Ethanol and Methanol solvents. Qualitative phytochemicals analysis reflects the presence of Phenol, Quinone, Steroid, Flavanoids and Terpenoid in the plant extract. TLC profiling of seed extracts give an idea about the presence of various phytochemicals. Different Rf (Retention factor) value of various phytochemicals provide valuable clue regarding their polarity and selection of solvents for separation of phytochemicals. INTRODUCTION: Cyamopsis tetragonoloba L. (syn. C. psoraloides) or cluster bean (also called as Guar, Guwar and Guvar bean), is a drought-tolerant summer annual legume and it is cultivated as a feed

Sunil H. Ganatra; Archana M. Ramteke; Shweta P. Durge; S. U. Patil; Dr. S. H. Ganatra

468

MOF Functionalization via Solvent-Assisted Ligand Incorporation: Phosphonates vs Carboxylates.  

PubMed

Solvent-assisted ligand incorporation (SALI) is useful for functionalizing the channels of metal-organic framework (MOF) materials such as NU-1000 that offer substitutionally labile zirconium(IV) coordination sites for nonbridging ligands. Each of the 30 or so previous examples relied upon coordination of a carboxylate ligand to achieve incorporation. Here we show that, with appropriate attention to ligand/node stoichiometry, SALI can also be achieved with phosphonate-terminated ligands. Consistent with stronger M(IV) coordination of phosphonates versus carboxylates, this change extends the pH range for retention of incorporated ligands. The difference in coordination strength can be exploited to achieve stepwise incorporation of pairs of ligands-specifically, phosphonates species followed by carboxylate species-without danger of displacement of the first ligand type by the second. Diffuse reflectance infrared Fourier-transform spectroscopy suggests that the phosphonate ligands are connected to the MOF node as RPO2(OH)¯ species in a moiety that leaves a base-accessible -OH moiety on each bound phosphonate. PMID:25665089

Deria, Pravas; Bury, Wojciech; Hod, Idan; Kung, Chung-Wei; Karagiaridi, Olga; Hupp, Joseph T; Farha, Omar K

2015-03-01

469

Crystal modification of rifapentine using different solvents  

Microsoft Academic Search

Rifapentine crystals with different habits were prepared by recrystallization from selected solvents, such as methanol, ethanol,\\u000a chloroform, and acetic acid. Scanning electron microscopy, X-ray powder diffractometry, infrared spectrometry, and differential\\u000a scanning calorimetry were used to investigate the physicochemical characteristics of the prepared crystals. The comparative\\u000a dissolution behaviors of the newly developed crystals and of rifapentine without being treated were also

Kun Zhou; Jun Li; Jianhong Luo; Dongsheng Zheng

2010-01-01

470

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.

471

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

472

Thermal Characterization of Nanofluids with Different Solvents  

Microsoft Academic Search

Thermal lens spectrometry (TLS) and photopyroelectric (PPE) techniques were used to obtain the thermal diffusivity and effusivity\\u000a of different nanofluid samples. The thermal effusivity of these samples was obtained by the PPE technique in a front detection\\u000a configuration. In the case of the determination of the thermal diffusivity, TLS was used for the different solvents in the\\u000a presence of gold

J. L. Jiménez-Pérez; A. Cruz-Orea; J. F. Sánchez-Ramírez; F. Sánchez-Sinencio; L. Martínez-Pérez; G. A. López Muñoz

2009-01-01

473

Brayton Solvent Recovery Heat Pump Technology Update  

E-print Network

approach. Two different demonstration units were installed and operated at 3M locations. They incorporated direct drive machinery (see Fig. 2). An improved process was developed by NUCON and installed at a pharmaceutical manufacturing plant which..., in the coat~ g of tablets in the pharmaceutical industry'/ the solvents used are methylene chloride d methanol. It is extremely difficult to these materials with activated carbon ystems because of the poor adsorption capaci for these high vapor pressure...

Enneking, J. C.

474

Modeling Remediation of Chlorinated Solvent Plumes  

Microsoft Academic Search

\\u000a Analytical and numerical modeling has emerged as a valuable tool for planning and designing groundwater remediation systems.\\u000a Models have been used in a variety of settings including (1) research into the fundamental processes controlling chlorinated\\u000a solvent fate and transport, (2) methods for integrating information on site hydrology, geology, contaminant distribution,\\u000a transport and fate, and (3) applied aspects of plume management

Hanadi S. Rifai; Robert C. Borden; Charles J. Newell; Philip B. Bedient

475

Catalytic oxidation of industrial organic solvent vapors.  

PubMed

In the present study the catalytic oxidation of an industrial organic solvent consisting predominantly of C-9 to C-10 paraffins and napthtenics and derived from low aromatic white spirit on CuO and Pt catalysts was investigated at ambient pressure and temperatures between 330 and 770 K. Catalysts were prepared in the laboratory and compared to commercial ones. Characterization was based on x-ray diffraction (XRD) analysis, x-ray fluorescence (XRF) analysis, scanning electron microscope (SEM) analysis and nitrogen adsorption data. The commercial platinum catalyst was proved highly efficient in the oxidation of the commercial solvent, necessitating lower temperatures for total oxidation. Catalyst loading in active component is clearly not of primordial importance, since its dispersion and crystallinity as well as the presence of other metallic compounds influence also the catalytic activity. In the case of copper catalysts studied, the different support (alumina) characteristics also would contribute to the difference in catalytic activity. Finally, the power law kinetics may successfully be used in order to explain the catalytic oxidation data of the organic solvent, where its constituents are modeled as a single carbon-containing compound. PMID:20390900

Tzortzatou, Katerina; Grigoropoulou, Eleni

2010-01-01

476

Solvent-dependent transition states for decarboxylations.  

PubMed

The rate constants and kinetic isotope effects for decarboxylation of 4-pyridylacetic acid depend strongly on whether the solvent is water or dioxane, and the present paper interprets this finding. We calculate the solvent dependence of the free energy barrier and of the (13)C and (18)O kinetic isotope effects using a quantum mechanical solvation model based on class IV charges and semiempirical atomic surface tensions. The calculations provide a consistent interpretation of the experimental results, which provides a striking confirmation of the soundness of the solvation modeling. Even more significantly, the agreement of theory and experiment gives us confidence in the physical picture of the reaction provided by the model. This indicates that the location of the transition state, as measured by the length of the breaking C--C bond, is 0.24 A later than the gas phase in dioxane and 0.37 A later than the gas phase in water. Charge development at the transition state also depends strongly on the solvent; in particular the CO(2) moiety is 0.07 electronic charge units more negative at the transition state in dioxane than in water. PMID:11480991

Sicinska, D; Truhlar, D G; Paneth, P

2001-08-01

477

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

478

Non-representative quantum mechanical weak values  

E-print Network

The operational definition of a weak value for a quantum mechanical system involves the limit of the weak measurement strength tending to zero. I study how this limit compares to the situation for the undisturbed (no weak measurement) system. Under certain conditions, which I investigate, this limit is discontinuous in the sense that it does not merge smoothly to the Hilbert space description of the undisturbed system. Hence, in these discontinuous cases, the weak value does not represent the undisturbed system. As a result, conclusions drawn from such weak values regarding the properties of the studied system cannot be upheld. Examples are given.

B. E. Y. Svensson

2015-03-06

479

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

480

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